How to properly cut threads on a lathe

Cutting threads on a lathe with various tools

Threaded connections are actively used in almost all sectors of human activity, from agriculture to the space industry. To cut threads in small volumes, a lathe is used in conjunction with a special tool: cutters, dies, taps and threading heads. The method is selected depending on the required strength, size, profile and location of the screw surface.

Features of thread cutting

When performing work on a turning wall with a cutter installed, the top of the tool draws a screw recess, moving along the axis of rotation of the workpiece. This groove is called a thread. It is characterized by the following parameters:

• Pitch is the distance between adjacent turns. Measured along the axis of the workpiece.
• The angle of increase in the helix is ​​an indicator of the inclination of the line relative to the plane perpendicular to the axis of rotation of the workpiece. It is determined by the rotation frequency of the part and the speed of movement of the cutting tool along its axis.
• Stroke (for multi-start thread) is the distance between the nearest turns formed by one thread.

There are 5 thread profiles that affect the characteristics of the threaded connection:

• round;
• persistent;
• rectangular;
• trapezoidal;
• triangular.

The surface of the part itself can have a conical or cylindrical shape. A helical line cut by a tool on a machine is formed in one or more passes. For threads with two or more threads, the latter are located equidistant relative to each other. To count their number, just look at the beginning of the thread surface.

Application of cutters

When cutting threads with a cutter, the following types of this tool are used:

1. Round. Installed in the hole in the end of the holder. They belong to the shaped type of incisors. Used for internal and external processing of workpieces.

2. Rod. The heads are made of various shapes and sections, located on the rod. To increase the service life of the tool, some models have hard alloy brazing on the working edges.

3. Prismatic. Installation on the lathe is carried out using a dovetail holder. They are subject to more sharpening than round versions and are suitable for processing parts exclusively from the outside.

The outer threaded surface can be cut on a machine with both straight and bent versions of the tool mounted in a mandrel, and the inner one can be cut with curved and straight ones. High-speed steel is used in the manufacture of cutters. Detailed characteristics are standardized, and together with diagrams and drawings are indicated in GOST 18876-73.

The thread profile corresponds to the configuration of the tip of the cutter, which, in turn, can be rounded or have a chamfer. Depending on the material of the workpiece, the rake angle of the tool is selected (0-25 degrees).

Thus, for hard and brittle parts this parameter is less than for those made of viscous and non-ferrous metals. There are detailed diagrams for choosing the cutting angle for most materials.

Before cutting an internal thread on a machine, it is necessary to drill a hole or additionally bore it.

The rear lateral angles of the cutters are set to be the same on the right and left sides, and are selected in such a way that there is no friction between the surface of the tool and the groove formed by it. When the thread lead angle does not exceed 4°, the indicator is set in the region of 3–5°. Otherwise, the angle is set within 6 - 8 degrees.

When cutting threads on conical and cylindrical steel workpieces, cutters with carbide inserts T15K6, T30K4, T14K8, T15K6 are used. When working with cast iron parts, tools made of VKZM, V2K, VK6M, VK4 alloys are used.

Technology for using turning tools:

• The cutter is fixed in the tool holder, and the workpiece is fixed in the centers or chuck of the machine.
• The cutter moves along the axis of rotation of the workpiece, drawing a helical line. Both movements are strictly consistent with each other. In other words, during one revolution of the part, the cutter moves by the calculated pitch of the future thread.
• The support is driven by the spindle through the gearbox and lead screw. In this case, the gear ratio must be equal to the ratio of the pitch of the lead screw to the pitch of the thread being cut.
• The cutter is fed according to one of the following schemes: parallel to the generatrix of the thread (only the cutting edge is in contact), perpendicular to the axis of rotation of the workpiece (the entire profile is in contact).
• To form threads with large pitches on a machine, the workpiece is pre-processed with a slotted cutter. Its profile angle differs by 5-10° from the thread profile angle.
• Labor productivity when working with lathes is low, since a lot of time is spent reversing the cutter and setting it to size.
• The work requires increased attention and is performed exclusively by a highly qualified specialist.

Technology for using taps and dies

The tap is used when it is necessary to cut internal, mainly metric threads in holes of small diameter. It is a screw-shaped steel rod with grooves for chip removal located in the longitudinal direction. The tool consists of the following parts:

• Shank;
• Calibration part;
• Fence part.

To form a high-quality thread with a tap, 3 types of this turning tool are used sequentially, which can be distinguished by the number of marks placed on the shank:

• Chernova;
• Semi-finish;
• Finishing.

The speed of work on a lathe with installed taps can be quite high. As an example, for aluminum, cast iron and bronze parts this technology indicator is about 6-22 m per minute, while for other materials it is from 5 to 12 m per minute.

The die is designed for cutting external threads. It is a flat cylindrical tool, in the center of which there is a hole with sharp edges and channels for removing chips. It looks like a nut.

The calibrating part of the die is located in its middle, and the intake cone is located on each side. The tool on the lathe is fixed into a die holder - a special chuck in the tailstock quill.

In order for the tool to enter the workpiece without effort, a chamfer is removed at the end of the workpiece, the height of which corresponds to the thread profile.

The dies can be split or solid. The diameter of the former is subject to adjustment within small limits, which makes it possible to restore the performance characteristics of the tool after wear. Solid versions are used to form high-precision threads. Alloy or carbon steel is used in production.

When using a die on a turning machine, the surface of the workpiece is subjected to preliminary turning to the required thread diameter, but taking into account the following tolerances:

• For threads 6-10 mm, the tolerance is 0.1-0.2 mm;
• For 11-18, the tolerance is 0.12 - 0.24 mm;
• For 20-30 mm, the tolerance is 0.14-0.28 mm.

The speed of thread cutting with a die installed in a lathe is adjusted in accordance with the workpiece material and directly affects the wear rate of the tool:

• For steel - 3-4 m per minute;
• For cast iron - 2-3 m per minute;
• For brass - 10-15 m per minute.

Application of Die Heads

When cutting threads on a screw-cutting lathe, the use of threading heads is used less frequently than the tools described above. The role of their working element is made by special combs of several types:

• prismatic;
• tangential;
• round;
• radial.

The first type of dies is used for cutting internal threads, the remaining three are used for external threads. A special feature of the tool is the automatic divergence of the working parts during the reverse stroke, which prevents their contact with the newly formed screw threads.

Threading heads on the machine are used mainly when high-precision work is required. When cutting threads on long screws and worms, the tool is mounted on the machine support. Round cutters are the most popular, as they are easy to maintain and have increased durability. For cutting internal threads on turret-type machines, exclusively prismatic dies with a special lead-in cone are used. The work is completed in one pass.

Thread control

• To check the condition of the thread during its cutting on the machine, a thread template is used - a tool consisting of plates placed in a cassette on which there are notches. The thread pitch is indicated on the flat part of the template.
• For comprehensive control, thread gauges of the go-through type (with a full thread profile) and non-go-through type (with a shortened profile, to check the average diameter) are used. They must be handled with extreme care. Otherwise, scratches and nicks may form on the jagged surface.
• The diameters of the cut thread, as well as its pitch, are checked with a thread micrometer - a tool equipped with mounting holes in the spindle and heel, which act as fasteners for replaceable inserts. The micrometer is installed in the rack, after which it is adjusted according to the standard sample.
• Before checking the thread of a part with any of the specified tools, it must be cleaned of dirt and chips without removing it from the machine.

Source: http://orgstanki.ru/narezanie-rezby-na-tokarnom-stanke-razlichnymi-instrumentami.html

How to cut threads on a lathe?

In the mass production of hardware, thread rolling is used on automatic machines. The production of individual parts is carried out by cutting threads on lathes. The pitch is maintained by a specially installed lead screw. Settings are performed using tables.

Threads with diameters up to 40 mm are made with taps and dies, regardless of the type of protrusion relief.

On large parts, weighing over 500 kg, with a diameter exceeding the length of the part, cutting can be done on rotary lathes that have a guitar in their design.

Thread cutting on a lathe

Methods for obtaining threads

Threads on a turning tank are cut in different ways depending on the type of connection and size of the part:

• roller knurling;
• using dies and taps;
• incisors.

When rolling, the profiled hard roller squeezes out a groove in the body of the hardware, lifting the metal of the protrusion. The method is highly productive. The thread itself is strong due to the hardening formed on the surface. In this way, it is possible to produce hardware from low-carbon ductile steels on automatic lines. For rolling when producing small batches of parts, a profile roller can be mounted on a lathe. Diameter is limited to 24–30 mm.

Thread cutting on lathes is carried out with special tools: taps and dies. The method is highly productive. Regardless of the type of thread and the number of starts, it is made in one pass. Increased strength and accuracy is achieved by using a pair of tools for diameters greater than 14 mm: roughing and finishing.

The cutter makes threads of any profile. The diameter and weight of the part are limited by the technical characteristics of the machine.

To turn conical threads on the cone of a threaded connection, a special tool and cutter are used. The machine must have all the components necessary to configure the cutting of conical threads. The thread pitch is set using tables located on the headstock or top panel of the gearbox. The part is ground to a cone according to the outer thread size. Sharpening angle 120⁰. The cutting depth is adjusted by the slide. After touching the cutter, it is aligned along the limb.

Tapered threads are measured and designated in inches. The pitch is determined by the number of threads in 1⁰ parallel to the axis of the pipe. You need to work according to tables. Check threads with templates and gauges. Direct measurement produces large errors.

In some conical connections, cutting metric threads along a cone is used. The stroke of the cutter parallel to the surface being processed is set by turning the slide.

Classification of threads

Division of threads by surface type:

• conical;
• cylindrical.

In the direction of the turn:

Without indicating the direction, the thread is cut in the left direction. It is considered standard. The same tool is used. It changes to reverse rotation, and the cutting edge turns over 180⁰ - the caliper is brought in from the opposite side.

The tooth profile in section has different shapes. Types of threads used, made on lathes:

• metric;
• metric-conical;
• cylindrical pipe;
• pipe conical;
• inch;
• trapezoidal;
• persistent;
• round.

To use taps and dies, the part is mounted in a chuck. The threaded cutting tool is pressed by the center of the tailstock. When cutting with a cutter, the long part is pressed by the tailstock, the short part by the mushroom. The tool is mounted on a support and aligned in the axis of the part.

Dies and taps for cutting

Threading tool

Work productivity is increased through the use of thread-cutting heads. They have 4 segments with incisors. Having cut to the end, the device opens, releasing the part. The tool does not need to be twisted. The thread is cut quickly, like with a tap. Diameters up to 100 mm can be processed.

Threading heads have a complex design and are used in the mass production of parts.

The cutter is sharpened using a flat template, regardless of the type of thread. The angle must correspond exactly to the cavity, following its contours. After cutting, the tops of the threads should be cleaned and slightly blunted.

In trapezoidal profiles, the corners of the peaks and valleys are rounded to R 0.3–0.5 mm. Otherwise, the threads will not twist well and will rest against the tips. With the tips stripped, the threads slide along the side surface when tightened, creating a strong connection.

The maximum load and the tightness of the connection increases.

The highest productivity when machining holes is provided by a tap for cutting internal threads. When the parts are aligned in the axis, it cuts through all the turns, regardless of the number of passes.

Threading technique

There are different ways to cut threads on a lathe. The part undergoes preliminary processing and preparation. For knurling, the outer diameter is made smaller. The metal is not cut, but pressed with a roller. Excess material rises to form ridges. The groove size is indicated in special technological tables.

Cutting with taps and dies requires a slight undersizing, by 2–5% of the thread height. The diameter for the cutter is made with a plus allowance. During the work process, all excess is cut off.

The part is mounted in a chuck. The long one is pressed up by the tailstock. The cutter is brought to contact. Then the cutting depth is set. At the end of the cut, the cutter is sharply pulled back.

When using a tap, it is pressed by the tailstock. The die and threading head can be mounted in a chuck. The hardware is brought to them with a second cartridge or caliper.

The method of cutting a screw thread on a lathe is determined by the number and size of the part, and the availability of the appropriate tool.
How to cut threads on a lathe 1k62

Source: https://metalloy.ru/obrabotka/rezba/narezka-na-tokarnom-stanke

Cutting internal threads on a lathe

The joining of structural parts occurs through bolts, screws and studs, which in turn have special external and internal threads. This kind of connection is called detachable. Bolts, screws and studs are cylindrical rods with screw threads. The thread cutting process is carried out mechanically and manually, on machines with special tools.

Processing methods

Internal threads are applied with taps, external threads with dies. Taps are shaped like a screw, with a groove along the screw part that will allow the chips to slide off during the process. The geometric shape of the dies resembles a nut. Capable of cutting threads with a diameter of up to 52 mm. There are round, square, hexagonal and prismatic.

Features of internal thread cutting

A thread is a reliable way to connect two parts; this indicator increases significantly if the thread is internal. Tapping is the removal of metal material using cutting edges at different pitches. The operation is performed in one pass. Depending on the intended purpose, swords are divided into: metalworking (metric and inch threads), nut, master and die. By type of thread - left-handed for creating left-handed threads and, accordingly, right-handed.

• method of processing with a tap

The internal thread is applied with a tap, which is made of carbon or high-alloy steel. The tool consists of a shank attached to a cup chuck and a working area - a cutting part with longitudinal and helical grooves. The intake part - the upper part of the cone, carries out thread cutting work. Calibrating part – calibrates the direction of the process. General operating rules:

• • It is not recommended to immediately apply threads to products made by casting or stamping. It is necessary to pre-drill the hole, thereby removing carbon deposits and scale;
• • on drilling machines, the tap must be secured in reversible chucks to avoid the possibility of breakage;
• • mandatory chamfering in those places where work is planned.

Regardless of the cutting method: manual or automatic (on machines), the use of coolant is an important component for obtaining a quality result.

• cutting method on a lathe

The main problem with using taps is chip removal in holes 6 mm and over 16 mm. Due to the limited space, chip removal is difficult, which can cause tool failure. On lathe-type machines, threads are applied using a boring cutter and carbide inserts with a full or partial profile.

Features of external thread cutting

Threads are grooves of various geometric shapes, cut with special tools - dies, thread cutters, taps and grinding wheels. The thread is applied either manually or using a lathe and cutter.

• method of cutting with a die and tap

A tap is a screw with straight and helical grooves, designed for cutting internal threads. The manual cutting method requires 3 taps: rough, for applying the initial thread, medium and finishing. The machine cutting method is carried out on lathes and milling machines.

The dies are similar in shape and appearance to a nut; on the inside of the tool there are conical cutting teeth for cutting external threads. They are divided into round, square and hexagonal shapes. According to the design - solid, split and sliding.

To ensure smooth passage of the die through the part, it is necessary to remove the chamfer.

• turning method

In production, threads are cut using a lathe and a special tool - a thread cutter. For each product, an individual indicator of the helical pitch is established; it is determined by measuring the distance between adjacent turns.

The part is placed in a lathe, and as the workpiece rotates, the cutter moves along all axes, creating a helical surface. Based on their design features, thread cutters are divided into: prismatic, rod and round/disc.

The thread profiles used are triangular, rectangular, trapezoidal, thrust and round geometric shapes.

Read also: Manufacturing of parts from steel 09g2s

Features of pipe threading

In pipe threading, 3 types are used: on a lathe, using a die or a pipe die. In practice, the most common thread is the triangular type:

• • inch, with measurement calculations in inches. The thread has high strength due to the large pitch and large profile. Used for water pipes;
• • metric, measured in millimeters, used for pipe fasteners.

The clamp is a tool of limited functionality, used only for cutting threads on pipes.
On lathes, the process is structured as follows: the pipe is fixed in the spindle, then all excess is removed with a cutting cutter, the appropriate pitch is selected and the thread is applied.

Thread cutting is one of the most common operations in metalworking. To perform it in non-serial production, universal screw-cutting lathes are used. These machines work with workpieces in the form of bodies of rotation and small parts of asymmetrical shape that can be mounted on the faceplate of the machine. In other cases, threads are obtained by milling, rolling and other methods.

Thread cutting on a lathe

To form threads on a lathe, cutting tools are used, the top of which moves at a constant speed along the axis of the rotating workpiece. In this case, a helix line is formed on the surface of the workpiece.

The inclination of the helix to the plane perpendicular to the central axis of the workpiece depends on the ratio of the spindle rotation speed and the tool movement speed and is indicated by the helix angle.

The distance between two adjacent identical thread elements, measured along the axis, is called the thread pitch.

When the tool is deepened into the workpiece along a helical line, a surface is formed with the same shape as that at the top of the tool. The thread profile is the contour of the thread section on a plane passing through its axis of rotation.

Depending on the profile, threads are divided into triangular, trapezoidal, rectangular and round, which are used extremely rarely.

Threads with a rectangular profile are persistent; they are used for threaded pairs operating under significant load.

Depending on the shape of the base surface, threads are divided into cylindrical and conical. Tapered threads are used in oil, water, fuel and air systems, in short, where a tight connection is required. Based on the type of base surface, threads can be divided into external and internal.

By direction, left and right threads are distinguished; the right thread is twisted when rotating clockwise, and the left thread is twisted counterclockwise. Based on the number of threads, threads are divided into single-start and multi-start. Multi-start threads allow you to travel a greater distance in one revolution. The number of passes can be determined by looking at the end of the part. Depending on the units of measurement, meter and inch threads are distinguished.

Thread cutting with cutters

Cutting turning threads with cutters is the most common method. It is used to create external and internal threads. To create threads, prismatic, rod and prismatic cutters are used. Their sizes and shapes are close to those of shaped incisors.

For external threads, straight and bent cutters are used; for internal threads, with a small hole diameter, curved cutters are used, and for large diameters, straight cutters mounted on a mandrel are used. It is impossible to make small holes with a cutter.

In blind holes, when making a thread with a cutter, a recess is provided for its exit and chamfers on the edges of the hole.

A large selection of cutters and other cutting tools for lathes can be found in the “Cutting tools for lathes” section.

Cutters for thread cutting have plates made of high-speed steels and hard alloys as a cutting edge. For preliminary operations, plates made of alloys T15K6, T14K8 and their analogues are used, and for finishing operations - T30K4 and T15K6. In processing cast iron workpieces, elements made from alloys V2K, VK3M, VK4, VK6M show high efficiency.

Internal thread cutting

For internal threads, in addition to cutters, taps and dies are used . The tap is a tool in the form of a threaded rod made of hardened steel. On the surface of the rod along its axis there are milled grooves, thanks to which the thread has cutting edges. The tail part of the tap has a square cross-section, which allows it to be secured in a chuck or driver.

Read also: Tabletop metal engraving machine

During thread cutting, the metal is not only cut into chips, but also plastically deformed due to the cutting of the tool, and the internal diameter of the hole increases. Taking this feature into account, the diameter of the thread hole is calculated by subtracting the thread pitch from the outer diameter of the tap.

There are many different taps, of which nut, hand and machine taps are widely used. To cut a thread using a tap, the part is fixed on the machine, a hole is drilled in it and the spindle is adjusted to the required number of revolutions. The tap installed in the tailstock is inserted into the hole due to the movement of the quill, and the part rotates.

Taper thread cutting

Of the conical threads, the most widely used is the standard one, which has a profile symmetrical with respect to the normal to the cone axis. To cut such threads, the same methods are used as for conventional cylindrical threads.

For external tapered threads, turning is carried out along the outer diameter to a cone. This can be easily done using thread cutters on a screw-cutting lathe using a copy ruler, but this method is characterized by low productivity.

On turret lathes, tapered threads are cut using dies. If it is necessary to obtain high-precision threads, then threading heads with dies of various shapes are used. During the operation, the dies automatically move apart.

Also, for tapered threads, rolling rollers are used, which allow thread rolling. For internal tapered threads, specially designed taps are used.

Setting up a lathe for thread cutting

To perform turning threads with the specified parameters, it is necessary to fine-tune the machine. First of all, you need to connect the rotation of the spindle with the movement of the caliper. The longitudinal feed per spindle revolution must be equal to the thread pitch.

Screw-cutting lathes allow you to adjust the feed of the cutter by interlocking the gears of their feed guitar and feed box. There are a large number of combinations of the clutch of these wheels, which allows you to configure the machine for any thread being cut.

Threads cannot be cut on a CNC lathe - basic mistakes

1. does not cut at all (the start light is on - the axes do not move - most likely there is no response about the spindle rotation speed from the sensor or the spindle rotation has not started) 2. does not get into the turns (the presence of large mechanical play, slipping of the encoder sensor or its kinematics) 3.

cuts threads with a pitch different from the specified one (check the thread cutting cycle, the maximum feed speed during thread cutting, work in mm) General checks - check the thread cutting program, entry and exit according to the operating manual (text provided for analysis) - check the suitability of the material, cutter , spindle revolutions, feed, spindle range - (thread pitch, mm) * (number of spindle revolutions rpm) should not exceed the maximum working feed speed along the axis (P1430) => reduce the spindle rotation speed (the problem occurs when cutting large threads with a pitch of more than 8-10 mm) - check the fastening of the electrical cables (connectors) and the cables themselves from the encoder to the CNC - check the fastening of the encoder on the spindle head, the encoder coupling, the gear on the encoder shaft in the spindle head - Check the parameter and set value of the sensor pulses spindle per 1 revolution. P3720=4096 pulses

*parameters are specified for Fanuc 0i series CNC

Source: https://morflot.su/narezanie-vnutrennej-rezby-na-tokarnom-stanke/

Thread cutting on a lathe: technology

Forming threads on metal workpieces in the form of bodies of rotation is one of the most popular and at the same time complex turning operations. The difficulty lies in both making basic equipment settings and preparing auxiliary tools. In order for thread cutting on a lathe to comply with the technical specifications, you must adhere to the technology for its implementation and do not forget about safety rules.

Preparing the machine

Regardless of the type of lathe and working tool, carving will be done by machining.

Through the machine settings, the operator determines the angle of the helical line of influence on the surface of the workpiece, which will have a perpendicular position relative to the axis of rotation.

Here it should be noted that the machines have different power and, accordingly, spindle speeds - in order for the cutting tool to efficiently cope with its task, it is important to initially correctly correlate the angle of influence and the speed of the engine.

An important parameter is the step between the cutting lines - it is also taken into account in the equipment settings and appropriate adjustments are made in terms of the position of the tool relative to the workpiece.

Since thread cutting on a screw-cutting lathe is usually carried out in several approaches, it is advisable to save the primary parameters until the operation is completed.

Even if the step along the threading line is maintained, there remains a risk of violating the positions of the beginning and end of the deformation sections, which may not coincide with each other. It is important to keep these nuances in mind before starting work.

Turners distinguish between even and odd threads. In the first case, we are talking about cuts, which ultimately form an even number of cutting lines in steps. Accordingly, odd cutting leaves odd threads. From the point of view of the operation, even cutting threads on a lathe will have its advantages.

For example, after each approach, the operator can launch a sliding nut in the support and quickly return it back with the cutter manually, without stopping the operation of the equipment.

Then, with each new pass of the sliding nut, the tool will automatically be directed to the original cavity, which ensures a certain accuracy of the operation.

In turn, odd cutting requires, after each pass, the support to return to its original position along with the cutter, which cannot be done without starting the reverse stroke.

Multi-pass and vortex cutting can be placed into separate categories. So, in the first case, cutting multi-start threads on a lathe will require precise angular separation of the workpiece during transitions from one groove to another.

The initial calculation of the pitch and cutting line parameters is important here. As for the whirlwind thread, it requires additional installation of a rotating cutting head on the support carriage.

Several individual cutters can be fixed on it, each of which will cover its own area of ​​work.

Inch cuts are used for metal pipes. Typically, such threads are obtained from fittings, which are subsequently used to assemble a metal or plastic pipeline. The standards for creating such cutting are determined by GOST 6357-81. Based on the technical document, we can conclude that the main parameters of inch cutting are pitch and diameter. Moreover, the second characteristic is estimated as the distance between the extreme points of the thread ridges.

Typical cutting of inch threads on a lathe is carried out by cutters and taps with modifications of the technology as applied to internal processing. Metric cutting is performed taking into account the same parameters, but the shape of the thread flange profile is added to them. In the case of inch cuts, it is most often sharp - in the shape of a triangle. In addition, as the name suggests, classic pipe cutting is calculated in inches, while metric pipe cutting is calculated in millimeters.

Forming threads with cutters

A cutter is a tool that directly performs cutting. It is made of carbide steel and before work receives a special sharpening in a shape that meets the requirements of the task. It can be used for threading bolts, nuts, studs and other workpieces. The cutter is installed in a machine chuck or multiple head. The work process is divided into several passes - upon completion of each of them, the tool is moved to the side.

Correction of thread formation parameters in this case is carried out by adjusting the caliper, which sets the required depth. At the same time, there are standardized settings. In particular, cutting threads on a lathe with a cutter in increments of up to 0.2 cm will imply that the feed in the transverse movement of the caliper screw will average 0.1 mm per pass.

Simultaneous work with two cutters is also allowed. But here it is necessary to take into account a nuance that can affect the quality of the thread line - the chips released by the leading cutter will cling to the waste of the second tool, which will have, although insignificant, still an impact on the parameters of the edge being formed.

Application of dies

Dies are purposefully used to work with the same hardware in the form of bolts and studs, but only when creating external threads. The area that is planned for slicing is pre-processed and cleaned.

Also, the diameter of the threaded surface is calculated so that it is smaller than the outer diameter of the applied thread. In the case of metric technology, this difference can be 0.2 mm for small threads.

To form a thread entry, a chamfer corresponding to the height of the thread profile is first removed at the end of the workpiece.

Although the process itself can be carried out manually, most often machine threading with a die is performed on a lathe using a special die chuck. The cartridge itself is fixed in the rear quill or in a head socket with several mounting niches. The average speed of such cutting will be 5-6 m/min.

Application of taps

Taps are used specifically for working with metric threads applied from the inside. In this case, the diameter should be no more than 50 mm. Lathes usually use machine taps, which allow the operation to be completed in one pass.

This opportunity largely arises due to the one-time use of several tools that are installed in multi-purpose universal chucks.

If in the case of a conventional cutter the process is divided into several stages by passes, then thread cutting with a tap on a lathe can be segmented according to the quality of processing with different types of tools.

Again, they work simultaneously, following one after the other, which compensates for the load that falls on one cutter. There are taps for roughing and finishing threads. Moreover, the first tool removes about 75% of excess metal from the target ditch.

Cutting with Die Heads

To use several cutters at the same time, special heads with chucks are also used. This is a revolving tool, into which you can integrate the same screw-cutting attachments - tangential, radial and round.

After cutting is completed, their combs diverge on the reverse stroke and no longer contact the completed thread.

The most common are round cutters of this type, since they are capable of several sharpenings, have increased durability and are easier to maintain.

However, internal threading on a turret-type lathe is performed only with prismatic combs that have a special lead-in cone. To work with worms and long screws, cutting heads are used that are integrated directly into the machine support. They allow you to form both external and internal threads.

Features of internal thread cutting

Different types of screw-cutting equipment can work on such threads. Unlike surface external machining, such operations require the initial creation of a hole by drilling. In some cases, a corresponding boring is required, which will allow the thread to be used in the future to mate with parts of a specific diameter.

But if the diameter is calculated incorrectly, cutting an internal thread on a lathe can ruin the workpiece. This occurs in cases where the initial diameter itself matches the dimensions of the target part that is to be integrated into the target cavity. This can be avoided by allowing technological thickening of the internal walls before drilling. This tolerance must correspond to the height of the thread flange.

End of thread line

The quality of the created thread will be determined not only by the accuracy of the edges and the convergence of individual sections that were performed in different passes. It is also determined by how the thread lines are completed. The technology requires that the contour end with a special waste groove - it will ensure the free entry of the screw part.

In addition, cutting threads on a lathe in the final stage should reduce the height of the flange. That is, when the working tool retreats, it forms a groove run-out, as well as its reduction. Sometimes, for a better design of the final line, a special pass is provided, which allows you to correctly adjust or even trim the already created groove run.

Cutting quality control

After completing the operation, the operator checks the thread for compliance with the required parameters. For this, a template is used, on the surface of which the imprints of the thread ridges are applied. There are different templates for metric and imperial threads, and both groups also have bars for checking the pitch, depth and angle of the grooves.

A comprehensive assessment is already given by calibers - these are devices that allow you to evaluate the correctness of the profile. If, for example, cutting a thread on a lathe with a cutter was carried out with a critical slope, this will be recorded with a suitable gauge. Micrometers and inserts are also used for similar tasks. Accurate verification readings are given only if the thread surfaces are pre-cleaned.

Conclusion

Creating threads on a lathe requires the use of high-quality cutting tools and the attentiveness of the operator himself. First of all, a device is prepared for cutting threads on a lathe in the form of a cutter, tap, die or turret. It is the user's responsibility to set up the equipment correctly.

The least hassle for the operator is the preparation of CNC machines with program control. They physically adjust and position the equipment according to specific data that is entered through a special input panel. The risk of making mistakes when working with such models is much lower than with conventional lathes.

Source: https://FB.ru/article/323248/narezanie-rezbyi-na-tokarnom-stanke-tehnologiya

Thread cutting on a lathe

The correct choice of method and tooling can optimize the threading process. Improved coatings and grades of materials used for modern turning tools in general have been developed for threading tools.

In addition, design improvements have been made to the threaded inserts, making chip control even more reliable.

However, despite these changes, manufacturing engineers pay insufficient attention to optimizing threading operations, viewing the process as something that is fixed and cannot be improved.

In fact, the turning process can be designed more efficiently. First of all, you need to understand more deeply some of the principles of thread cutting.

Why are there stringent requirements for thread cutting?

Thread cutting on a lathe has more stringent requirements than conventional turning operations. The working forces when cutting threads are usually higher, and the radius of curvature of the cutting edge of the threaded plate is smaller, which reduces its durability.

When turning, the feed must exactly match the thread pitch. If the pitch is 8 threads per inch (25.4 mm), then the tool must make 8 revolutions per inch, going 3.175 mm per revolution. Compare this to a conventional turning operation, where the feed rate is typically around 0.3 mm per revolution. The feed rate in thread cutting is 10 times higher than in conventional turning, and the corresponding forces on the edge of the threaded insert can increase from 100 to 1000 times.

The tip radius corresponding to this force is typically 0.4 mm, compared to 0.8 mm for a conventional turning insert. As for the threaded insert, this radius is severely limited by the permissible radius at the root of the thread defined by the relevant standard. The radius is also limited by the cutting operation required, since conventional turning is not applicable due to possible thread deformation.

As a result of the high cutting forces and their denser concentration, threaded inserts are subjected to much greater stress than conventional turning inserts.

Rice. 1. The partial profile insert can be used for different pitches when cutting to different depths. The smallest pitch of the thread being cut is determined by the small radius of curvature of the apex (not shown in the diagram). The largest pitch of the thread being cut is determined by the strength of the tip rounding zone

Full and partial profile plates

Inserts with an incomplete profile machine the root of the thread without reaching the top (see Fig. 1). One insert can handle a variety of pitches, down to the coarsest (lowest thread count per inch), determined by the strength of the cutting edge radius.

The cutting edge radius must be small enough to allow the insert to machine a variety of thread sizes. Small steps require a very tight radius, allowing the insert to penetrate deeper.

For example, cutting an 8 TPI thread with a partial profile insert requires a plunge depth of 2.7 mm, while the same thread cut with a full profile insert requires a depth of 2 mm. At the same time, a full profile insert allows for stronger threads.

Moreover, thread processing with such a plate requires four times fewer passes.

Rice. 2. Multi-tooth inserts have a number of consecutive teeth. This increases the efficiency of thread cutting, but the cutting forces are high.

Multi-tooth inserts

Multi-tooth inserts have a series of teeth arranged in series, where each subsequent tooth cuts deeper into the thread cavity than the previous one (see Fig. 2). The number of steps required to cut threads with such an insert can be reduced by up to 80 percent. Tool life is significantly longer than single-tooth inserts because the last tooth accounts for only half or a third of the total metal removed.

However, due to high cutting forces, these inserts are not recommended for thin-walled parts to avoid strong vibrations. In addition, the design of the workpiece processed by such an insert must have enough grooves for all teeth to exit the cutting zone.

Entry depth per pass

The penetration depth per pass is an extremely important thread cutting parameter. Each subsequent pass uses more of the insert's cutting edge. If the penetration depth per pass is constant (which is not recommended), then the cutting force and metal removal rate can increase significantly with each pass.

For example, when cutting a 60-degree thread with a constant plunge depth of 0.25 mm per pass, the second pass removes three times as much metal as the first. And with each subsequent pass, the amount of metal removed increases exponentially.

To avoid this and maintain more practical cutting forces, the plunge depth must be reduced with each pass.

Rice. 3. The choice of infeed angle has a significant impact on process efficiency

Plunge methods

There are at least four cutting methods (see Figure 3). Few people know how much the choice of a particular method can affect the efficiency of thread cutting.

A. Radial plunge

Although this is the most common thread cutting method, it is the least recommended. If the cutter is fed radially (perpendicular to the axis of the workpiece), metal is removed from both sides of the thread profile, resulting in a V-shaped chip.

This chip shape is difficult to break, so chip management can be a problem.

In addition, both sides of the cutting edge are exposed to severe heat and impact, which significantly reduces tool life compared to other plunge methods.

Rice. 4. Instead of a V shape, as a result of a one-sided lateral plunge, chips are formed, similar to those obtained during standard turning

B. One-sided side entry

In this method, the plunge direction is parallel to one side of the thread and the tool generally moves along the line at an angle of 30º. As a result, chips are formed, similar to those obtained during conventional turning (see Fig. 4).

Compared to radial plunging, chip formation and separation from the cutting edge is easier, which guarantees better heat dissipation. However, with this method, instead of cutting, friction of the auxiliary cutting edge occurs on the side surface of the thread.

This leads to abrasion, negatively affects surface finish and can cause vibration.

C. Modified Single Side Plunge (Recommended)

This method is similar to the single-sided lateral plunge method, except that the plunge angle is less than the thread profile angle - less than 30º. It retains the benefits of the single-side plunge method without the problems associated with the secondary edge. The best result is achieved with an insertion angle of 29½º, but in practice any angle from 25 to 29½º is acceptable.

D. _ Double side entry

In this case, the insert is fed alternately along both sides of the thread profile and, therefore, both sides of the cutting edge are involved in the process. This distributes the load and helps increase tool life.

However, such plunging can also cause problems with chip flow, which can degrade surface quality and tool life.

This method is usually used only for very large pitches and for thread shapes such as trapezoidal and ACME.

Rice. 5. Adjustment relative to the helix angle, as in the "slant" plate on the right, allows the rear angles of the main and minor edges to be aligned. This ensures more even wear

Aligning back corners

Some threaded inserts and holders have the ability to accurately tilt the insert in the plunge direction as the helix angle changes. This property ensures high quality threads by preventing friction of the plate against the side surface of the profile. It also allows you to extend the life of the cutter due to the uniform distribution of cutting forces along the entire length of the cutting edge.

An insert that does not have this feature, where the cutting edge is fed parallel to the centerline of the workpiece, forms unequal clearance angles of the main and minor edges of the insert (see Fig. 5). In particular, with a large pitch, this inequality can cause friction between the edge and the surface of the thread profile.

Adjustable systems allow you to change the angle of the insert by acting on the holder head using support plates. Fine adjustment results from aligning the angles of the main and minor edges, resulting in more even wear.

Rice. 6. This special thread cutting tool is used to process two separate threads simultaneously on a six-spindle lathe. Threads are processed separately. The inserts used here are intended for thread milling tools, but in this case they are used as turning tools.

Miniaturization and specialization

Insert cutters provide internal threading in holes up to 7.6 mm in diameter. There are many benefits to using lathe tools to cut threads in such small holes. The quality of the threads produced is generally higher, the insert design helps remove chips from the hole with little damage to the thread, and the ability to index the inserts reduces tooling costs.

These types of tools typically use carbide to allow low speed machining. When it comes to tapping small holes, using a low cutting speed is the only feasible option due to machine kinematics limitations.

Technological innovation has expanded the applications of thread-cutting tools, and the move to cutting small-diameter internal threads with cutters is a prime example of this.

Despite the wide range of standard tools, manufacturers continue to face certain problems that justify the use of specialized equipment (see Fig. 6.).

Special tooling, designed in collaboration with the supplier, is an opportunity that cannot be neglected when searching for rational cutter parameters for a particular type of work.

Source: http://TverdySplav.ru/narezanie-rezby-na-tokarnom-stanke/

All about cutting threads on pipes: 4 secrets of a turner

Author Dmitry 779 Date Aug 31, 2016

Detachable connections of metal pipelines in a home water supply and sewerage system are made using threads. Inch pipe threads are used on pipe ends and fittings.

The diameter of its cutting is determined by the size of inches, or their fractions, where the characterizing value is the number of turns made according to the number of turns on the length of a single inch.

The main advantage of a threaded pipe joint is the ability to disconnect and replace one worn part, instead of removing the entire structure and welding installation of another. Cutting inch threads is done using dies, taps, or special cutters.

Pipes with threaded inch thread

The thickness of the pipe walls is added to the diameter of the internal hole of the pipeline. If the inch size is 25.4 mm, then the pipe inch size is 3.3249 cm. The choice of the inch part determines the exact match of the cross-sectional dimensions.

What is an inch thread?

Threaded connections are characterized by the following factors: by type of fit: sliding, clearance, transitional, interference fit. According to the use of complementary parts: conventional direct connections and in combination with elements: ball, sleeve, spiral. Without or with a stopper.

1. cylindrical or conical shape
2. cutting method – external and internal cutting,
3. type of direction of the screw line - left and right,
4. approaches – multi-entry and single-entry,
5. profiling parameter: metric, cylindrical, trapezoidal, conical pipe, conical inch, round, rectangular, thrust,
6. Dimension – metric thread or inch pipe thread,
7. purpose - for fastening, running threads, regulating,
8. type of processing: cutting a part with a cutter, die, tap.

Bushing with inch connection

In modular slicing, the pitch is determined by modules. To convert to mm. "M" is multiplied by the number pi.

Pitch threads are measured in pitches (to determine the number of inches, pi is divided by pitch).

Options

GOST for inch threads 6257 - 81 determines the main precise parameters of the pass pitch and diameter. In this case, the measurement of the outer pipe diameter is equal to the distance between each upper point of the opposing ridges. The diameter of the internal lumen is measured from one point at the bottom of the groove cavity to the opposite point. The thread pitch is a constant value, it is measured by the distances between adjacent ridges or depressions.

Differences between metric and inch threads:

• metric dimensions - in mm, inch dimensions - in inches or their fractions,
• inch threads are characterized by sharper angles of inclination of crests and valleys,
• The threads have a rounded shape.

Upper angle size = 55 degrees, thread pitch is measured by the number of threads.

The following types of products are used in everyday life:

with a parameter of 1 inch - 14 threads, step length 1.814 mm, diameter ¾ or ½,

11 threads in 1 inch - with a pitch size of 2, 309, and a diameter of 1; 1 and ½; 1 and ¼.

Relation between inch and metric threads:

Table of ratio between inch and metric threads

Making pipe threads

Threading is done on a lathe with a cutter, as well as with the help of dies, combs and taps, manually or mechanically. To clarify the dimensions, you will need a thread gauge tool (comb, gauge) or a caliper.

To find out the step using a ruler, or determine it with a caliper, you need to measure the length of two or three passing steps, then divide by the number of steps. When checking with a thread gauge, the teeth of the nail file should fit tightly and without gaps to the thread being measured.

The accuracy of measurements depends on the following conditions:

• degree of wear and cleanliness of the part;
• convenience of measurement operation,
• cleanliness and appearance of the instrument,
• correct use of the measuring instrument.

Using the inch method, calculate the number of threads per 1 inch of pipe. After processing, verification is required.

To determine the pitch of an inch thread using a fitting (coupling) with an internal thread of the required dimensions, you need to screw a bolt into the part. If it goes in smoothly, tightly, effortlessly, then the pitch and cutting diameter dimensions are selected correctly. To measure the external size of the ridges, screw-on parts of the nozzle are used. If the sizes do not match, use other calibers in turn until they match.

How to use a thread gauge? The plates that are included in the tool are applied to the external, then internal thread of the pipe. If the profile corresponds to the size of the file, it is clarified visually: the free clearance is examined. Exact match means the size parameters indicated on the files (plates) of the thread gauge.

Calipers and micrometers accurately measure only outer diameters, so a more acceptable option is to use a thread gauge.

To avoid mistakes, you need to measure each diameter of the part three times, calculate and select the average value.

To avoid mistakes, you need to measure each diameter of the part three times, calculate and select the average value.

Example of an adapter with applied internal and external threads

Pipe thread cutting

To accurately cut threads on a lathe (inch), it is important to choose the right tools: an inch thread gauge is used to determine the pitch and design of the cutter.

Then determine the direction of the thread and fine-tune the parameters for the machine.

Cutters for cutting threads are sharpened taking into account the size of the rake angle γ = 0, and are adjusted exactly at the linear height of the center of the machine. Profile angle = 55 degrees.

The thread cutter for external threads is supplemented with durable steel plates (or carbide). The part is processed under the condition that the size of its outer diameter is smaller than the cutting diameter, since during processing the metal is deformed, leading to an increase in the diameter of the workpiece.

To make the internal surface, the workpiece is first bored or drilled, then ridges should be cut to create a ledge of 2 - 2.5 mm. (to accurately determine the last cut of the cutter) then it is removed.

For accuracy, use a template, combine the thread cutting tool with the template, focusing on the clearance in strict accordance with the center line of the machine.

Thread cutting with a cutter on a machine is done in stages.

• After each operation, the cutter is moved to its original position.
• New depth parameters are set and the working passage is repeated, while shifting the cutter to the right or left, and moving the caliper by 0.1 - 0.15 mm.
• Number of passes 3 – 6 roughing, only 3 finishing operations. For them, cutters are used, supplemented with soft-spring holders so that the surface is even and smooth.
• When performing a rough cutting, the turning cutter is mounted on a rigid holder.
• The head of the flat cutter, which performs internal cutting of the part, is adjusted perpendicular to the axis of the part in order to obtain a symmetrical element to avoid distortion.
• To perform finishing operational passes when machine-cutting coils, durable spring holders are used.
• Rough working thread cutting on a machine is done with a cutter mounted inside a rigid structure holder, and the finishing operation is done with a cutter placed inside a springy machine holder.

To simplify the manual cutting operation, use a KLUPP device, consisting of a body with handles, equipped with movable combs, or buy a special die, complete with profile replaceable combs.

A carefully executed inch pipe thread is a guarantee of safe, long-lasting operation of the water supply system at home, so if you do not have specific cutting skills, order the production from a master turner or milling machine.

Source: https://trubexpert.ru/repair/vsyo-o-narezke-rezby-na-trubax-sekrety-tokarya/

Cutting threads with a cutter on a lathe: how to do it with a tap, die, video

In order to cut threads on a lathe, different tools can be used. Experienced craftsmen most often do this using a cutter.

But you can also use special-purpose working heads, taps, and dies. This operation is also carried out using knurling technology.

In this article we will figure out what types of threads there are, how to obtain them using different methods, and how to check their quality.

Receipt methods

There are two main methods for obtaining threads. They are divided into cutting and rolling. Also different methods are used for internal and external threads.

For example, for external work, you need to use different dies, cutters, thread cutters and combs, or rollers on thread rolling machines.

When choosing one method or another, you need to take into account the desired thread profile, the nature of the material, the required volume and accuracy.

Classification

There are a huge variety of carving types. They differ in profile shape, location, direction of entry, step size and many other parameters.

According to the shape of the thread profile there are

• Trapezoidal.
• Rectangular.
• Round.
• Persistent.
• Triangular: metric; inch; pipe

In direction of calls

By location

• External (like a bolt).
• Internal (like a nut).

On the surface on which the carving is made

• Cylindrical.
• Conical.
• According to operational purpose.
• Fasteners.
• Fastening and sealing.
• Running gear.
• Special.

How to cut on a lathe?

For example, cutting on a lathe using a cutter will look like this: the cutter moves along the axis of the rotating part, which moves back and forth in relation to the cutter, and with its pointed tip draws a screw-type line.

The helical line differs in the angle of its rise or increase. The magnitude of this angle is perpendicular to the axis of rotation, it is measured between the tangent and is determined by: the amount of feed of the cutting tool, which moves along the axis, with the rotational speed of the part.

Cutting internal and external

To cut internal or external threads, you need to use a rod cutter. Their production differs only in the shape of the cutter. For external applications, straight or bent incisors are used.

And for the internal ones, curved or straight incisors. The location of the cutter edge must coincide with the profile of the thread being processed.

Cutting with taps and dies

External threads are cut using dies. The part area is pre-processed. The diameter of the surface to be machined should be slightly smaller than the outer diameter of the thread.

First, a chamfer corresponding to the height of the thread profile is removed. Then the die is installed in the chuck (die holder).

And the speed is selected in accordance with the desired thread (it is indicated on the back of the machine).

Taps are often used for internal metric threads. As a rule, machine taps are used on the machine, this allows the part to be completed in one pass.

For threads made of hard, viscous materials, sets of 2–3 taps are used. In a set of two, the right one does 75% of the work, and the second one only brings it to the desired size.

In a set of three taps, the right or roughing one does 60% of the work, the middle (semi-finish) 30% of the work, and the third 10%.

Using Die Heads

Threading heads are used for pipes and bolts. They are installed in the machine, then the desired diameter is adjusted and moved along the pipe. They are able to carry out work with high precision.

Universal heads allow you to install dies from different companies. It is also possible to lubricate the combs and adjust the sizes; manual clamping is often found.

Features of the left

First, you need to switch the operating mode of the lead screw so that it starts turning to the left. This is done by switching the lever that determines the direction of unwinding. And then everything happens exactly the opposite compared to the right-hand thread.

You just need to take into account that when switching to reverse, the cutter will not move to the side of the tailstock, but, on the contrary, will move towards the chuck. To avoid their collision, you must carefully monitor your movements.

Quality control

To ensure that the workpiece has been processed correctly, it is necessary to use thread templates. With their help, the thread pitch is checked.

But for a comprehensive assessment, a thread gauge is used. For convenience, it is installed in a rack and adjusted according to a standard or template, then the movement of the part itself is checked.

You can also use the simplest and most commonly used method. Take a nut or bolt and scroll it over the completed part.

If scuffing is noticeable on the thread as you move, or more effort needs to be applied, then you have made an error in your work. Now you already know how to use a lathe to make various nuts, bolts or threaded connections.

It is important to remember that such parts require great care and tenderness with each pass, and even quality control. It’s better to spend more time on work than to ruin several pieces later.

Interesting video

Source: https://vseostankah.com/tokarnyj-stanok-po-metallu/narezanie-rezby-reztsom.html

The principle of thread cutting on a lathe

A tool is brought to a rotating workpiece fixed in the spindle. The tool cuts into the workpiece and moves along it at the same speed. The tip of the tool leaves a spiral-shaped line on the workpiece, called a helix.

The thread has the following parameters:

• Location. The thread can be on the inner and outer surface.
• Direction. There are left and right threads. A product with a right-hand thread is screwed clockwise; this direction is more common.
• Step. Represents the distance between identical points of adjacent helical lines, measured along the central axis of the workpiece. It is regulated by the ratio of the tool movement speed to the workpiece rotation speed.
• The slope of the helix. This concept is related to step. Determined relative to a plane perpendicular to the axis of the workpiece. The tangent of the angle of inclination is equal to the pitch divided by the product of π and the outer diameter of the workpiece.
• Type of supporting surface. There are cylindrical and conical threads.
• Profile. It represents a thread contour in a longitudinal section. Depending on the profile, threads are divided into triangular, rectangular and trapezoidal.
• Number of threaded lines. According to this parameter, threads can be divided into single-start and multi-start. The number of starts is visible at the ends of the thread; depending on this parameter, the distance that the screwed or screwed part travels in one revolution varies.

Thread cutting using cutters

The most widespread application is cutting threads with a special thread cutter. The profile of the cutting edge of the cutter determines the profile of the thread. The cutting edge is made of hard and high-speed alloys.

Preliminary preparation of the part before cutting an external thread consists of turning it to a diameter that is 1/40-1/12 smaller than the thread diameter. During thread cutting, the metal deforms and the outer diameter of the thread increases.

Similar preparation, only in the opposite direction, is carried out for cutting internal threads.

In this case, a hole with a diameter larger by 0.2-0.4 mm is processed when working with viscous materials such as steel, titanium, bronze, and by 0.1-0.02 mm when processing brittle materials: bronze, cast iron, high strength steel.

Thread cutting using cutters is performed in several passes. After one pass, the cutter moves to its original position. Thread cutting is performed with only one cutting edge of the tool; simultaneous use of two edges leads to a decrease in surface quality. The number of roughing and finishing passes is determined by the workpiece material, cutter, thread height, and requirements for the cleanliness of the thread surface.

Thread cutting using dies and taps

The die is intended for cutting external threads, and the tap is intended for internal threads. Pre-treatment of surfaces is also carried out taking into account the deformation of the metal. The disadvantage of this method of creating threads is the limitation of the diameter. Dies cut threads with a diameter of up to 30 mm, and taps up to 50 mm.

On screw-cutting lathes, the die is installed in a chuck secured in the tailstock quill. The cutting speed of steel workpieces is 3-4 m/min, cast iron 2-3 m/min, soft copper alloys 10-15 m/min.

The tap in many cases allows you to make a thread in one pass. For hard materials, sets of 2-3 tools are used. The rough tap removes 75% of the metal, the finishing tap does the finishing. The cutting speed for steel is 5-12 m/min, for cast iron - 6-22 m/min. When cutting threads, coolant is supplied.

Thread cutting using die heads

Threading heads are used to produce threads on turret machines and automatic lathes. They are quite complex devices compared to cutters, a tap and a die.

Heads for cutting external threads are a hollow cylinder containing combs - elements with a cutting surface. After the working pass, the combs open and do not touch the thread during the return stroke.

Heads intended for forming internal threads have the opposite structure. They are made in the form of a shaft, in the front part of which there are combs. Their number depends on the diameter of the head. The cutting edge of the combs has a lead-in cone, which simplifies the start of thread cutting. The diameter of the dies is adjusted using a thread gauge or a reference part.

Source: https://stankomach.com/o-kompanii/articles/narezanie-rezby-na-tokarnom-stanke.html

Thread cutting on lathes

Threading is a broad topic in metalworking using lathes. This technology is used in more than 40% of works. The strength of the connection between detachable structural elements or mechanisms depends on the quality of the threads. Read more about this in the article.  

Equipment used

Threads are cut by hand or on screw-cutting lathes. When cutting manually, a vice and tools are used: dies and taps. You can cut threads using a 16K20 screw-cutting lathe with a cutter, tap, die and other types of tools. They cut both external and internal threads.

On the feed box of the 16K20 machine there is a table that indicates the positions of the handles in order to adjust the desired thread pitch. Setting processing modes allows you to obtain a high-quality part. The technology for using the cutter provides:

• sharpening it correctly;
• setting machine operating modes;
• correct installation of the cutter in the center of the part using a device - a template;
• measuring the resulting dimensions using threaded templates or gauges.

When forming threads, the following are not allowed: scuffing, crushing, torn threads, risks.

A special fixture or vortex heads with a separate drive expand the functionality of lathes.

Turret lathes increase machining productivity by reducing the time required to change tools.

Source: https://stankiexpert.ru/stanki/tokarnye/narezanie-rezby-na-tokarnykh-stankakh.html