3 ways to sharpen a drill bit for concrete
Drilling a concrete surface is performed with a special tool, which becomes dull with active use. In this case, you will need to sharpen the concrete drill. This procedure is carried out in several steps. The result is to return the original geometric dimensions of the drill and continue the construction process.
Why is sharpening required?
Drills with a length of up to 7 millimeters are suitable for sharpening.
The device is designed to work with concrete and other high-strength materials, so it is made of heavy metals. Tools for drilling concrete, brick, and ceramics have a special tip made of titanium and tungsten. When working for a long time, as well as when the recommendations for using the tool are not followed, difficulties arise due to the fact that the element has become dull. Sharpening will help return the original characteristics and dimensions.
General rules and recommendations
If the drill becomes very hot, it is necessary to allow it to cool naturally without immersing it in water.
- You can perform the operation on a special grinding wheel.
- Avoid heating the plate. Drills for concrete cannot tolerate this; they can simply burst. Therefore, you should take short breaks to allow the instrument to cool down. You can do this by immersing yourself in cold water.
- In case of strong heating, do not allow contact with water. Cooling should be gradual and in the air.
- If sharpening is done correctly, then the cutting edges are straight, of the same length and sharpening angle, and the intersection coincides with the rotation.
Sharpening methods
Three key methods:
- screw;
- conical;
- two-plane.
However, a victorious drill can become dull. It behaves exactly like a metal tool - it drills hard, overheats and emits annoying ultra-high-frequency noise during operation. The basis for sharpening Pobedit drills is approximately the same as for metal equipment, however, there are certain significant subtleties.
Screw sharpening
Screw sharpening has three movements: rotation around an axis; reciprocating movement along and turning movement.
Difficult work, as it requires special skill at the initial stage.
It is carried out with the assistance of a diamond wheel, and after completion, cuts are made with a needle file. It is worth focusing on turning on both working sides.
This method allows you to obtain a sharp increase in the clearance angle by more than 20% towards the central part of the drill, and has advantages over the more often used conical or two-plane sharpening.
Conical
This type is the easiest. Creates a sharp increase in drill angle from behind. The work takes up to two minutes. Rules for sharpening:
- The tool should be secured to the platform.
- Bring it to the machine for five seconds.
- Then remove the drill and turn it over. Repeat the procedure.
In order for drills to last a long time, you don’t need to try to drill a hole on the first pass.
Biplanar
The angle when sharpening a cutting tool must be equal to 60 degrees. Suitable for correcting mistakes that were made previously.
With this method, it is worth considering for what purpose the tool will be used, mainly for those materials that are not very hard. The main thing with all methods is to be careful and error-free.
The specificity of the tool is that during the processing of hard materials, the jumper on the cutting part, which is located in the middle of the fragment of the upper part of the drill, will be subject to wear.
Source: https://ZnayBeton.ru/rabota-s-betonom/instr/kak-zatochit-sverlo.html
How to sharpen a drill for concrete: differences between Pobedit and conventional tools, performance of the work
Drills designed to perform work on such complex materials as concrete are made using carbide plates, which are soldered onto their cutting part.
Like any other, such a tool wears out during use, which is when the question arises of how to sharpen a drill for concrete.
To restore the geometric parameters of the working part of a concrete drill without damaging the tool itself, you can try several methods of sharpening it, each of which is relevant under certain circumstances.
A pobedite drill with blunt edges takes a long time to drill but overheats quickly
Equipment requirements
The only equipment we have is an electric sharpening machine. But just because it exists does not mean that you can sharpen drills on it. It is necessary that the sharpening disk has the correct shape - that is, the shape of a cylinder with a smooth, not rounded edge. A convex edge with ground edges may result in incorrect sharpening.
If the disk is very worn out, it is better to replace it with a new one or correct it with a special CBN “pencil”, if you have one on the farm. It is very good if the disk is balanced and does not produce beats or vibrations (in fact, this is a mandatory norm). Only the peripheral surface of the disk is involved in the work, not its ends.
There is a temptation to use the flat side surface of the disk. But after several sharpenings it will lose its shape and fixing the stone after that will be much more difficult.
Types of products
The peculiarity of the drill for concrete is the presence of a special solder, made of an alloy of very high strength, almost as hard as diamond. Such pobedite tools are superior in strength to all other products.
They can be classified as:
- Drill bit. The shank of the structure is made in the shape of a cylinder or polyhedron.
- Drill bit for hammer drill. The shank has the shape of a cylinder with recesses, and its surface is marked SDS MAX or SDS PLUS.
Making a hole in reinforced concrete using a simple drill is not always possible. For this purpose, a hammer drill is used with a hammer drill for concrete, which is called a drill.
To imagine how a drill differs from drills for different materials, it’s worth getting acquainted with what these tools look like:
| Drill type | Peculiarities |
| The tool has a steep spiral of different types, which allows the dust generated during drilling to be quickly removed from the hole. Used for drilling large diameter holes. | |
| The length of the tools ranges from 100 mm to 1 meter, which allows you to make holes of sufficiently deep depth. Debris is removed from the drilled hole faster than with a spiral device. Its advantage is ease of use and no need to sharpen the tool. | |
| Used for passages of small diameters and depths. It is not intended for very strong concrete. After working with such a tool, it takes a lot of time to remove debris from the hole. The advantage of flat drills is high strength and reliability. |
Table 2 - drills:
| Photos of drills for different materials | Peculiarities |
| |
for bronze, duralumin, brass - within the range: 110° - 120°. | |
|
Sharpening auger for concrete
The hammer drill has a carbide plate as the cutting part, inserted into a slot at the working end and secured with solder. A normally sharpened drill has clear cutting edges with a sharpening angle of about 90 0 and an angle between the edges at the apex of 130–140 0.
With standard sharpening, the front edge of the cutting edge (directed in the direction of rotation) is inclined to the drill axis at an angle of 30 0, and the rear edge is inclined at an angle of 60 0. When manually sharpening, without special tools, you can focus on the entire, unworn part of the edges and reproduce their angles of inclination.
Sharpening process
We start sharpening from the front edges. We position the drill near the peripheral surface of the stone so that the cutting edge is parallel to the axis of the sharpener and directed upward, and the edge is parallel to the surface, and lightly press the drill against the sharpener for a short time.
A clearly visible mark remains on the metal, which shows whether its position was chosen correctly. The plane of the test section should coincide with the plane of the edge, and the spot of the section should be located in the center of its unworn part, without significant displacement.
Having found the correct position experimentally, remember it and begin sharpening.
Parallelism is not difficult to achieve if you bring the cutting edge to the surface of the stone and navigate along the gap left before contact.
Source: https://instanko.ru/osnastka/kak-zatochit-bur-po-betonu.html
How to sharpen drills and augers for concrete: instructions for beginners
From the author: Hello, dear readers! A DIYer's pantry can contain many different tools. The composition of such an arsenal varies widely, depending on the preferences of the owner. But, regardless of the degree of personal skill, the nature of hobbies, skills, design features of the apartment and other factors, there are certain points of contact and coincidence.
Such general points include a pobedit drill, without which in typical mass housing it is impossible to even hang a closet, not to mention any larger-scale events. This is exactly the tool that is in every apartment. Or almost every one. Therefore, knowing how to sharpen a drill for concrete is important for anyone in modern conditions. Moreover, there is nothing tricky in this process, and no special skills or special tools are required.
Like any cutting tool, a drill loses its properties during use. When working with concrete, brick, stone, the cutting edge becomes dull very quickly - the abrasive properties of the material being processed affect it, so the sharp edge is quickly erased and “blurred”. Of course, you can buy a new tool and throw away the dull one. But this is not a completely rational action, since the residual life of drills or drills is still decent.
Often in the budget segment there are drills and drills that are not sharpened by the manufacturer - the master himself has to choose the optimal type and angle. Therefore, the skill of straightening and sharpening such a tool will not only make some types of work easier, but will also save the family budget.
The difference between a pobedit drill and a regular drill
Traditional drills for metal or wood are most often made of tool steel or the so-called high-speed cutter - an alloy steel that can withstand temperatures and high cutting speeds. With materials like brick, tile, stone and concrete, this option is not suitable because:
- abrasive working environment;
- the instrument heats up quickly and intensely;
- Due to the heterogeneity of the material being processed, the working edges experience strong impact loads.
Therefore, drills and drills have a complex design. The main part of the tool, which is responsible for the removal and ejection of drilling products and fastening the tool in a hammer drill or drill, can be made of inexpensive, low-alloy steel. And as a cutting element, a pobedit plate is used - a special alloy of tungsten carbide with a small addition of cobalt and carbon. The plate is attached to a steel shank using copper soldering.
This tip resists abrasion well and can withstand high temperatures. But it is quite fragile and requires attention when sharpening. The service life of a drill or auger is most often determined by the degree of wear of this particular plate.
Drilling performance largely depends on proper sharpening of the tool.
Now about the differences between a drill and a drill. A drill for stone or concrete with a pobedit tip differs little from a drill for wood or stone in appearance, approach, and sharpening.
The usual one allows for impact during drilling, but is still more suitable for drilling. Therefore, only one rear edge is sharpened. The drill was created to work with a hammer drill, where impact prevails over rotation.
That is, the drill works both as a chisel and as a drill. Therefore, it sharpens from both edges - both the back and the front.
The design of the shank depends on the mounting method in the tool. The design of the spiral that removes crumbs from the cutting zone may also vary. The differences are largely due to the tool production technology and the characteristics of the material to be worked with.
Although the configuration of the spiral part is only important when drilling deep holes. In small drills there is a body without a spiral at all or with a spiral made as schematically as possible, even primitively.
Although there are modifications and four-way ones, in which the problem of dust removal is radically solved.
Basically, the performance characteristics of a drill or auger depend specifically on the condition of the pobedite soldering, so when sharpening for materials with different characteristics, you should pay attention to this part of the tool. Although the general principle remains unchanged. The harder the material to be drilled, the smaller the angle given to the cutting edge.
Drills are a very specialized tool - for each material there is one.
Choosing a tool base for sharpening
You don't need much to sharpen drills at home. A simple electric sharpener, better known as “emery”, is enough. At the same time, the power of a simple household model is quite enough, and there is no need to be puzzled by the search for some kind of professional device. The optimal size is one that allows you to install grinding wheels with a diameter of 200 to 300 mm.
The grinding wheel itself can be diamond or CBN - the best choice. But, if they are not available, then the more familiar silicon carbide will do. Those who are not well versed in sharpening wheels can be guided by the color of the stone. For victory, gray or greenish is suitable. Red and white are no good.
The winner itself tolerates intense heat well. But the solder, with which it is attached to the body of the drill, and the steel from which this steel is made, do not tolerate overheating during sharpening. Therefore, care should be taken to cool the drill in advance. That is, prepare a small container of water.
Pobedit does not like thermal shocks, like most solid materials. That is, when a heated pobedite drill tip is lowered into water, it can collapse and crack. To prevent this from happening, the drill being sharpened, when it heats up, is first cooled in air for some time and only then dipped into water. The duration of exposure to air depends on the intensity of heating and the size of the drill.
By the way, if you are not confident in the correctness of independently determining the critical temperature point for safe cooling with water, then it is better to do without it altogether - regularly cool only in air. True, this method will delay the sharpening process.
The difference between a drill and a drill is simple: the diverting spiral does not start immediately from the cutting edge, but a little later
Safety precautions
First of all, you need to follow the rules for safe work on sanding wheels. It's simple. Be sure to use safety glasses to protect your eyes from pieces of scale and abrasive, even if the sandpaper is equipped with a transparent protective screen. It is imperative that you do not wear gloves on your hands - it is enough to catch one thread, and the whole hand will be wrapped in the mitten after it. For the same reason, we carefully fasten all the buttons (especially on the sleeves) - and no fluffy, fluttering clothes.
The sharpening stone must be carefully aligned and free from runout - ultimately, compliance with this point will also affect the quality of sharpening. The rest should also be adjusted - a large gap between it and the stone is a source of potential danger, especially when sharpening thin drills, since both the drill and your fingers can get caught there.
In general, there is one more rule for working safely with power tools: don’t be afraid of them. But showing respect is a must.
Execution of work
Let's start with the fact that when sharpening drills, we pay special attention to symmetry. Otherwise, there may be beating and uneven wear of the tool, or even breakage. Although, when compared with a drill for metal, such perfectionism is less important for a pobedite drill - slight sharpening flaws are quickly leveled out by themselves during the work process. But you should still strive for accuracy.
The second difference between sharpening a drill for concrete and one intended for metal is that the latter has a slightly rounded rear edge; it seems to change the angle behind the cutting edge. This is not required for a concrete drill - the trailing edge forms a flat plane.
For both a hammer drill and a drill designed to work with a drill, the apex angle should be about 110–130 degrees. That is, this is the angle that two cutting edges form when they converge at the tip.
Particular precision in determining angles is not required. Approximate values, “by eye”, are sufficient. If the eye is weak, which is especially true when sharpening small-diameter drills, then you can make a template from a pair of nuts, as indicated in the video.
The drill, as already mentioned, only sharpens the back edge. Its sharpening angle is approximately 60 degrees to the axis. In this case, the plane must be uniform. It’s good to evaluate this by the reflection - an uneven finish on the working plane indicates that there are several planes.
Then you need to adjust until one comes out. To prevent this from happening, it is enough to fix the drill, pressing it evenly against the stone, and not try to tighten it.
That is, we move the drill relative to the stone left and right to wear the stone evenly, but do not change the angle of the drill relative to the stone and the tool rest.
Important point! With pobedit drills, it happens that the leading edge is covered with solder. Then you need to sharpen it too. We simply remove excess metal along the axis of the tool, opening it up. It is important not to overdo it here, otherwise you can loosen the fastening of the plate to the steel base.
A hammer drill is, in principle, sharpened in exactly the same way. Only the leading edge is also added, it is given an angle half as small - 30 degrees relative to the axis of the drill.
Usually one leading edge is sharpened, then the drill is turned 180 degrees and the second edge is adjusted. The rear edges are sharpened next - in the same way, one by one.
If the drill is not sharpened from scratch, but only straightened, it is worth ensuring that all traces of wear are removed from the drill head. Only then will he begin to drill normally.
We also pay attention to the tip of the drill - the place where both leading and trailing edges meet. There should be a bridge between the working edges (where the back edges meet).
The smaller it is, the more accurately and faster the drill will drill, but the faster wear occurs. By changing the sizes of the front and rear edges, you can ensure that this jumper disappears altogether - such a drill is useful for drilling ceramic tiles without hitting them.
But for concrete, it is still better to leave the lintel (0.4–5 mm, depending on the diameter).
You can sharpen the drill a little differently - with a self-centering tip, the so-called. “sharp” or “step” sharpening. Its essence is that a spike is formed at the top of the drill, which centers the drill and allows you to more accurately maintain the direction when drilling without impact. The essence of the method can be seen in these videos.
While practicing the skill of sharpening drills and augers, do not hesitate to make useful simple devices on the advice of the masters. As a rule, such products do not require special expenses, but the quality of work increases significantly. They also make it easier to learn useful skills so you can do without them later. But as long as your hand is not full and your eye is not developed, such equipment will save you from a lot of unpleasant moments.
Source: https://seberemont.ru/kak-zatochit-sverla-i-bury-po-betonu/
How to sharpen a drill bit for concrete
It does not require special proof that the drill during operation loses the sharpness of the cutting part, that is, simply put, it becomes dull. A dull drill isn't a problem until it's needed.
Then it suddenly turns out that it is impossible to work with a worn or dull drill. We can only regret that the geometry and size of the drill were not restored in time.
This article will tell you how to sharpen a twist drill and a hard-tipped drill bit for drilling concrete.
You don’t have to worry about sharpening a wood drill; you can work with such a drill for many months and even years without any sharpening. Unfortunately, the same cannot be said about a metal drill, which must be sharp. That is, you can drill metal only with a sharp, well-sharpened drill.
Loss of drill sharpness is characterized by a sharp creak at the beginning of drilling. A drill that is not sharpened in time generates more heat and thus wears out even faster than a sharp one.
You can sharpen a drill on special machines or using devices. Naturally, if possible, it is preferable to do this on special equipment. But in a home workshop, as a rule, there are no such machines, so you have to use a regular electric sharpening machine with a stone.
Main components of a twist drill.
So, let's look at how to sharpen a drill for metal? The type of sharpening depends on the shape that should be given to the back surface of the drill and can be single-plane, two-plane, conical, cylindrical and helical.
The drill is sharpened along the back edges. Both teeth (feathers) of the drill should be sharpened exactly the same. It's not easy to do this manually. It is also not easy to manually maintain the desired shape of the back edge and the desired back angle.
1. Single-plane drill sharpening is characterized by the fact that the back surface of the pen is made in the form of a single plane. The rear angle ranges from 28-30°.
The drill is simply attached to the circle, so that the cutting part runs parallel to the circle and sharpening is carried out without rotating or moving the drill.
With such sharpening, the cutting edges of the drill may become chipped during drilling, which is a disadvantage of this sharpening method. This is the easiest method of manual sharpening, which can be used for a thin drill with a diameter of up to 3 mm.
2. Drills with a diameter of more than 3 mm are preferably sharpened conically. It is difficult to perform such sharpening manually without skills, but it is possible. The drill is taken with the left hand by the working part as close as possible to the fence cone, and with the right hand by the tail.
The drill is pressed against the end of the grinding stone by the cutting edge and the back surface, and is slightly rocked with the right hand, creating a conical surface on the back feather edge. During sharpening, the drill does not come off the stone, hand movements are slow and smooth.
For the second pen everything is repeated in the same way.
Move the drill with its cutting edge to the grinding wheel.
We swing the drill down and then up again.
When sharpening, you should try to maintain the original shape of the factory surface of the rear part as much as possible in order to maintain the desired rear angles. If sharpening is done correctly, then it is quite sufficient for drills with a diameter of up to 10 mm. For diameters above 10 mm, this sharpening can be improved by sharpening the front surface, as shown in the photo:
Front surface point.
What is the point of a point? By reducing the rake angle and increasing the cutting edge angle, chipping resistance increases, which increases drill life. In addition, the width of the transverse edge becomes smaller. The transverse edge does not drill, but scrapes the metal in the central part of the hole. The second picture clearly shows that here it is shortened, which makes drilling easier.
For drills with a selected small clearance angle, you can further sharpen the flank. In this case, the drill rubs less in the drill hole with its back surface. See photo:
Rear surface undercut.
In production conditions, after sharpening, as a rule, finishing is done, which smoothes the surface, removing small nicks. A drill that has been fine-tuned wears out less than a simply sharpened drill. If possible, fine-tuning should be done.
For finishing, you need to use grinding round stones made of green silicon carbide (grade 63C, grit 5-6, hardness M3-SM1) on a bakelite bond, as well as wheels made of CBN LO (grit 6-8) on a bakelite bond.
Below we present to your attention an excellent selection of training videos by watching which you will definitely be able to sharpen your drills.
How to sharpen a tipped pobedite drill bit
A pobedite drill bit can also become dull. A dull drill overheats during operation, drills poorly and makes a loud squealing sound. Of course, you can change the drill by buying a new one, but it’s better to save money and sharpen it yourself.
To do this you will need a sharpening machine (electric sharpener) with a diamond stone and coolant. An ordinary emery stone is not suitable for sharpening a Pobedit drill. Before you start sharpening, make sure that it is possible in principle. To do this, measure the height of the cutting part of the drill.
When the height of the cutting part of the drill, i.e. soldering, is about 10 mm, sharpening is possible.
Don’t forget: the harder the material, the lower the sharpening speed should be. The angular speed (the number of rotations of the stone) when sharpening a pobedit drill should be reduced, regardless of which tool is used for sharpening.
It is recommended to sharpen tipped drills in the same way as simple small-diameter drills, i.e. The back surface should be sharpened flat. In this case, the back surface should be sharpened as shown in the photo, grinding the drill down to the soldering point:
Sharpened drill bit with soldering.
It is advisable to sharpen the front surface. If the soldering has already been ground down to the very drill, then it is simply impossible to do without sharpening, since the soft metal extends to the cutting edge from the front surface. The front surface is simultaneously ground down so that the thickness of the soldering center becomes smaller.
Solder point on the front surface.
When sharpening the drill, try to be precise and carefully ensure that its cutting sides are the same size. If this cannot be achieved, then the offset center of the spine will certainly result in the drill hole being enlarged and uneven.
Regardless of the device on which sharpening is performed, it is necessary to control the ratio of the front and rear angles of the cutting edge in the direction of rotation. Another rule that should be followed in order to properly sharpen a drill for concrete: the harder the material, the greater the sharpening angle.
For victory it is 170 degrees.
During the sharpening process, the drill must not be allowed to heat up, because Cracks may appear and the carbide plates may peel off. In order to prevent this, you should periodically cool the drill with liquid. You can use regular water for cooling.
We invite you to watch a selection of videos on sharpening drills with pobedite tips.
: Sharpening drill bits for hammer drills. Part 2
Source: https://betonzavod-info.com/kak-pravilno-zatochit-sverlo-po-betonu/
Sharpening drill bits for concrete
Concrete drills are made of a hard special alloy. Drills most often have a soldered tip made of a very hard alloy based on titanium and tungsten. These drills can be used to drill stone, concrete, brick, ceramics, marble and some other similar materials.
Drills for concrete with a tip made of titanium and tungsten alloy, used for drilling stone, brick, marble, ceramics.
It is necessary to distinguish between drills and concrete drills.
They differ in the shape of the shank. The concrete drill is designed for an impact drill and has a standard shank shape, the same as an ordinary drill for metal or wood. The drill is intended for a hammer drill and has a shank for an SDS-design chuck. Today, there are 2 types of SDS shanks: some have a diameter of 10 mm, and others have a diameter of 18 mm.
To drill reinforcement, it is necessary to replace the drill with metal drills.
It should be borne in mind that the concrete device is designed to work with stone, concrete, ceramics and other similar materials. They should not drill into wood or metal. If, while drilling concrete, the drill comes up against steel reinforcement, you will need to replace it with metal drills, and then drill through the reinforcement. After this, you can continue drilling into concrete.
Today, there are methods that make it possible to sharpen such structures on concrete in such a way that they can also drill into metal. However, these methods are considered to be artisanal, and therefore, their use is not recommended.
Work process
When drilling (drilling) solid concrete, it is necessary to monitor overheating. Every 10-15 seconds you will need to let this drilling structure cool down. Under no circumstances should you cool it with water or any other liquids. High-quality modern drills can withstand fairly high heat (more than 1000 degrees).
It happens that a hard stone can get caught in concrete. If an impact drill is used, it may not drill through the stone. In such a case, you can take a special chipper or some old similar drilling device for concrete and, using a heavy hammer or sledgehammer, you can try to manually crush such a stone. After this, you can continue with the drilling process.
The hard stone in concrete is crushed by hand using a heavy hammer or sledgehammer.
Drilling into stone and hard concrete is a somewhat labor-intensive process, especially if you plan to use an impact drill.
In some difficult cases, for example, when you need to make holes in ceilings or load-bearing walls, you should use a hammer drill in impact drill mode.
Especially when making a suspended ceiling and it is necessary to make holes to secure profiles in the concrete floor, you should not try to work with a drill. The apartment owner will only get tired and lose some time.
Sometimes concrete drills are sharpened using a grinder with a diamond blade. If the work is carried out using a hammer drill and there are high-quality drills, they will not require sharpening.
Do not use the impact drill mode when drilling ceramic tiles. Ceramics must be drilled using a concrete drill, but in the mode of an ordinary drill. Do not press too hard, otherwise the tile may crack.
Basic Rules
Dull concrete drill bits can be sharpened on a corundum grinding wheel.
Like any cutting tool, concrete drills will gradually become dull and lose their properties. However, at home this happens somewhat slower, and therefore the cutting tool is most often not sharpened at all - the easiest way is to purchase a new one. However, if there is such a need, carbide tips of drills can be sharpened on a corundum grinding wheel in the same way as ordinary devices.
It is imperative to take into account the fact that concrete drills are afraid of heating when sharpening - in this case, the carbide plates fall off and crack. Therefore, the tip will need to be cooled with water from time to time, and then ensure that the drill does not get too hot on the sharpening stone.
If the tip does get hot, it is strictly forbidden to immerse it in water - the plate will immediately burst. This drilling device must be allowed to cool slowly and gradually in the air.
To protect the drill bits from heating up when sharpening, the tip must be cooled with water.
In case of correct sharpening, the cutting edges must be straight, and their intersection must exactly coincide with the axis of rotation of the drill. If the length of the cutting edges is not the same, the short one will be less loaded during operation than the longer one. Consequently, the long one will become dull much faster.
In addition, under the influence of increased loads from the longer edge, the drill may begin to be pushed away from the axis of rotation. As a result, the drill may break. If the sharpening angles of the cutting edges turn out to be different, only the edge that has a larger sharpening angle will work. This can also lead to the risk of breaking the drill during operation and to a one-sided load.
Several ways
A drill, penetrating into the material being processed, must come into contact with the workpiece exclusively with its cutting edges. All other points on the flank surface must have clearance with the bottom of the hole (cutting surface). For clearance to exist, the shape of the back surface must be different from the shape of the bottom of the hole.
There are a fairly large number of possible sharpening methods that make it possible to create the desired clearance angles, the gap between the back surface of the drill and the cutting surfaces. Depending on the shape that the back surface will receive, they can be divided into helical, conical and flat sharpening methods.
Using a conical sharpener
When conical sharpening a drill, it is necessary to correctly set the geometric parameters.
Conical sharpening is the most common method. The drill is installed in a prism, which has the ability to swing around an axis that is inclined to the working surface of the grinding wheel. The swing axis and the drill axis are crossed. This means that they will lie in two parallel planes.
The drill, which is fixed in the prism, is brought to the grinding wheel. The rear surface will take the shape of a section of a conical surface. The vertex of the cone will lie at the intersection of the generatrix of the working surface of the circle with the swing axis.
Depending on the geometric sharpening parameters that were specified. When conical sharpening you should adjust:
- The distance between the crossing axis of swing, which is the axis of the sharpening cone, and the axes of the drill (h).
- Distance from the drill axis to the tip of the sharpening cone (H).
- The angle of intersection between the axis of the sharpening cone and the axis of the drill (o).
- Half the sharpening cone angle (b).
Two types of conical sharpening are used:
To obtain other values for the inclination of the transverse edge, change the parameters and settings.
- The tip of the sharpening cone is located higher than the tip of the drill. In this case, the settings will be as follows: a = 45 degrees, b = 13-15 degrees, H = 1.9D, h = (0.05-0.08)D. The angle of intersection of the axis of the drill and the cone in this case is less than the angle φ0 between the axis of the generatrix of the grinding wheel and the drill.
- The tip of the sharpening cone is lower than the tip of the drill. The distance of the tip from the drill is H = 1.16D, half the sharpening cone angle b = 30-35 degrees, the intersection angle of the drill axis and the cone axis is o = 90 degrees, offset h = (0.05-0.08)D. For this type of sharpening 0 > f0.
The specified installation parameters are capable of providing clearance angles for the peripheral point a = 5-7 degrees, a leading angle 2f = 116-118 degrees, and an inclination angle of the cutting transverse edge Ф = 55 degrees.
If there is a need to obtain other values of the rear angles a and f (inclination of the transverse edge), the setting parameters should be measured.
The clearance angle is adjusted by changing the distance h between the crossing axes of the drill and the sharpening cone. The inclination angle of the cutting transverse edge (φ) is by rotating around an axis, the planing angle is a change in the angle o and b. With increasing distance between the axis of the drill and the axis of the sharpening cone (h), a will increase, and angles φ and 2φ will decrease. An increase in o, b and H, on the contrary, reduces 2f, f and a.
The clearance angle, which is measured in cylindrical sections, increases as it approaches the drill axis during conical sharpening.
Cylindrical section of the drill.
The first type of sharpening is capable of creating a sharper increase in the rear angles. Such a change in the rear angles is favorable. This is explained by the work of the drill. In addition to the rotational movement during operation, the drill will move along the axis.
Consequently, the trajectory of each of the points is a helix. This line is inclined to the cutting plane, which is determined without taking into account the axial movement of the drills at an angle m.
Its value is determined by the formula tg m = So / pD, where So = feed, mm/rev.
The actual clearance angle will decrease by a value of m. The closer the point in question lies to the drill axis, the more the clearance angle, which is measured during operation, will decrease. Consequently, an increase in clearance angles closer to the axis, which can be obtained with conical sharpening, will help increase durability.
Use of screw
When using the screw method, automation of the sharpening process is possible.
Screw sharpening is the method that makes it easiest to automate sharpening. The drill will be given rotation and two translational movements, which are coordinated with it, in relation to the grinding wheel. One of the movements is directed along the generatrix of the circle, the other along the axis of the drills. Oscillating is the movement along the generatrix of the circle parallel to the cutting edge, because it will not create back angles.
The backing movement is along the axis of the drill. During the screw sharpening process, there are 2 sections on the cutting edge: section 0-1, which is located on the diameter of the core. Sanded with a wheel edge. Section 1-2 of the circle's generatrix. In section 0-1, a sharpening of the jumper can be observed. In this section, the plan angle will decrease by the value of the angle v, which is formed by the vector vc. It is equal to the sum of the oscillation vectors v0 and the backing vectors v3 with the direction of the oscillation vector.
In a cylindrical section, the back angle in section 1-2 will be determined by the value of the backing vector: tg a = 2 | v3 | / (wD) or tg a = 2H3 / (nD), where H3 is the backing stroke, w is the angular speed of rotation of the drills.
The oscillation stroke is assumed to be approximately equal to or slightly greater than the core diameter. Relief angles will increase with increasing backing stroke. The clearance angles will not change as the oscillation stroke increases.
Diagram of screw drill angles.
Just as with conical sharpening, with helical sharpening the clearance angles, which are measured in a cylindrical section, increase as they approach the axis of the drill. In this case, the increase in the rear angles occurs to the same extent as their decrease as a result of the peculiarities of the drilling kinematics. Consequently, when setting even small clearance angles on the periphery, it will be possible to obtain clearance angles of the required size close to the drill axis.
When sharpened with a screw, the transverse cutting edge will become less durable as a result of sharpening. This will worsen the operating conditions of drills during drilling of strong and hard materials and cause increased wear of the transverse edge due to increased specific loads.
In the process of drilling materials of relatively low strength (aluminum alloys, cast iron and others), the strength of the tips will be quite sufficient. The drill can easily penetrate the material being processed. This can significantly improve drilling productivity and accuracy.
When working with solid carbide drills, two-plane sharpening can provide high durability when drilling material of relatively low strength and hardness - aluminum alloys, cast iron, non-metallic materials. When drilling hardened and difficult-to-cut steels with two-plane sharpening, increased wear of the cutting transverse edge near the centering point at the tip will be observed.
Source: http://o-cemente.info/instrumenti-dlja-betona/zatochka-sverla-po-betonu.html
Sharpening a drill for concrete: methods, parameters, angles
Drills designed to perform work on such complex materials as concrete are made using carbide plates, which are soldered onto their cutting part.
Like any other, such a tool wears out during use, which is when the question arises of how to sharpen a drill for concrete.
To restore the geometric parameters of the working part of a concrete drill without damaging the tool itself, you can try several methods of sharpening it, each of which is relevant under certain circumstances.
A pobedite drill with blunt edges takes a long time to drill but overheats quickly
Sharpening rules
Sharpening a drill for concrete can be carried out on a corundum grinding wheel installed on appropriate equipment. Such drills are sharpened in the same way as regular ones, but there are a number of nuances that should be taken into account.
Carbide inserts, which are equipped with the cutting part of concrete drills, are very critical of severe overheating. The latter can cause the plate to crack or even separate from the main body of the tool at the point where it is soldered.
That is why, in the process of sharpening drills for concrete, they should be cooled with water as often as possible, without bringing the cutting part to overheating.
It should be taken into account that a very hot tip of a concrete drill, if it has reached this state, should under no circumstances be immersed in water: it must cool slowly under natural conditions. Sudden cooling of carbide inserts can cause them to simply burst.
The cutting edges of the drill should be sharp without roundness
The concrete drill should be sharpened in such a way that its worn cutting edges become straight, and the place where they intersect exactly coincides with the axis of rotation of the tool. In addition, it is necessary to ensure that the machined cutting edges of the carbide insert are of the same length. In this case, the load perceived by each of these edges will have the same value, and accordingly, they will wear out evenly.
A difference in the length of the cutting edges of a concrete drill can also cause the tool to be pushed to the side during the drilling process under the influence of the higher load created on the longer cutting part, which will ultimately lead to its breakage.
The sharpening angle of the cutting edges is another important parameter that you should pay attention to. If the uniformity of this parameter for two edges is not maintained, then the edge with a larger sharpening angle will work and, accordingly, be actively loaded. This will also lead to rapid tool failure.
Knowing the basic principles of proper sharpening of drills for concrete, you can sharpen the tool quite well even in the most “field” conditions. The main thing is to exercise extreme caution so as not to get injured!
How to sharpen a drill
During the drilling process, the tool used to perform such an operation must contact the material being processed only with its cutting edges. That is why the back surface of any drill must be sharpened at a certain angle, which ensures the presence of a gap between it and the bottom of the hole being formed (cutting surface).
Today, three main methods of sharpening drills for concrete are used, which make it possible to give the back surface of the tool a certain shape. Let's consider these methods in more detail.
Conical sharpening
The most common way to restore the geometric parameters of drills used for concrete work is conical sharpening.
The tool to be sharpened is installed in a special prism, which has the ability to move (swing) around its axis, located at a certain angle to the working surface of the grinding wheel.
The rear surface of the cutting part of the concrete drill takes the shape of a cone with the apex located at the intersection of the working surface of the grinding wheel with the axis of the prism's swing.
A sharpening device, even a relatively simple homemade one, allows you to evenly sharpen the cutting edges of the drill
To sharpen a drill using this method, you must configure the parameters indicated in the table.
- the distance between the axis of the sharpening cone (the axis of the tool’s swing) and the axis of the drill itself (h);
- distance from the top of the sharpening cone (H) to the axis of the drill;
- the angle at which the drill axis (o) and the sharpening cone axis intersect;
- half the value of the angle located between the sides of the sharpening cone (b).
Scheme of conical sharpening of a drill
For conical sharpening of a concrete drill, you can use two methods:
- The top of the tool to be sharpened is located lower than the top of the sharpening cone. When sharpening a drill for concrete in this way, use the following settings: a – 45°, b – 13–15°, H – 1.9 D, h – (0.05–0.08) D. In this case, the “o” angle located between the axis of the drill and the guide of the cone, is less than the angle between the axes of the tool and the circle forming the shape of the grinding wheel (φ0).
- The top of the drill being sharpened is located higher than the top of the sharpening cone. For this sharpening, the following parameters are used: the distance of the top of the cone from the top of the drill (H) – 1.16 D; half the angle at the apex of the sharpening cone (b) – 30–35°; the angle at which the drill and cone axes are located (o) – 90°; displacement (h) – (0.05–0.08) D; angle φ0 > 0.
A tool for working on concrete sharpened using these methods has the parameters indicated in the table.
Table from text
The value of the rear angle of the cutting part is changed by adjusting the value h - the distance between the intersecting axes of the sharpening cone and drill.
To change the angle of inclination of the transverse cutting edge (φ), it is necessary to rotate the drill being sharpened around its axis, and to change the angle in the plan, the angles “o” and “b” must be changed.
If you increase the distance between the axis of the sharpening cone (h) and the axis of the drill, then the angle “a” will increase, and the angles “φ” and “2φ” will decrease. An increase in the parameters “o”, “b” and “H” leads to a decrease in the values of φ, 2φ, as well as the angle “a”.
Geometric parameters of the cutting part of drills with pobedit plates
The conical sharpening method is preferable, since it creates a sharper increase in the back angle of the drill. When drilling concrete, the tool performs a rotational movement and at the same time moves along its axis, so the trajectory of movement of each point of the cutting part is a helical line.
The value of the angle “m” at which such a helix is located to the cutting plane without taking into account the axial movement of the tool is determined by the following formula: tg m = S0/nD, where S0 is the drill feed, measured in mm/rev. From this formula it becomes clear: the closer the point on the surface of the cutting part is located to the axis of the drill, the smaller the clearance angle in the plane under consideration will be.
This property of conical sharpening, which assumes that the clearance angle in areas of the working surface of the drill approaching its axis increases, helps to increase its durability.
Two-plane sharpening
This method of sharpening drills is used primarily in cases where they are planned to be used for drilling materials that are not characterized by too high hardness and strength. The peculiarities of a tool with such sharpening are that when processing materials that are too hard, the jumper on the cutting part, located in the central part of the tip of the drill, will be subject to active wear.
Geometry of double sharpening of a Pobedit drill
When deciding how to sharpen a pobedit drill, you should first of all take into account exactly what materials will be processed with its help. Moreover, any sharpening method requires strict adherence to the recommendations for performing this procedure.
In conclusion, we present to your attention a video on how to properly sharpen a concrete drill bit for a rotary hammer.
Source: http://met-all.org/oborudovanie/prochee/kak-zatochit-sverlo-po-betonu-pobeditovoe.html
Do-it-yourself concrete drill sharpening - YUG-ZhBK
Concrete drills are made of a hard special alloy. Drills most often have a soldered tip made of a very hard alloy based on titanium and tungsten. These drills can be used to drill stone, concrete, brick, ceramics, marble and some other similar materials.
Drills for concrete with a tip made of titanium and tungsten alloy, used for drilling stone, brick, marble, ceramics.
It is necessary to distinguish between drills and concrete drills.
They differ in the shape of the shank. The concrete drill is designed for an impact drill and has a standard shank shape, the same as an ordinary drill for metal or wood. The drill is intended for a hammer drill and has a shank for an SDS-design chuck. Today, there are 2 types of SDS shanks: some have a diameter of 10 mm, and others have a diameter of 18 mm.
To drill reinforcement, it is necessary to replace the drill with metal drills.
It should be borne in mind that the concrete device is designed to work with stone, concrete, ceramics and other similar materials. They should not drill into wood or metal. If, while drilling concrete, the drill comes up against steel reinforcement, you will need to replace it with metal drills, and then drill through the reinforcement. After this, you can continue drilling into concrete.
Today, there are methods that make it possible to sharpen such structures on concrete in such a way that they can also drill into metal. However, these methods are considered to be artisanal, and therefore, their use is not recommended.
High-quality sharpening of drill bits for concrete – Tool Stroy
Drills designed to perform work on such complex materials as concrete are made using carbide plates, which are soldered onto their cutting part.
Like any other, such a tool wears out during use, which is when the question arises of how to sharpen a drill for concrete.
To restore the geometric parameters of the working part of a concrete drill without damaging the tool itself, you can try several methods of sharpening it, each of which is relevant under certain circumstances.
A pobedite drill with blunt edges takes a long time to drill but overheats quickly
