All photos from the article

Now manufacturers produce many types and sizes of cutters designed for processing different materials, including wood. You can sharpen a blunt fixture with your own hands on a universal or special machine, as well as manually.

Features of cutters

For the production of cutters are used different materials. Tool steels are suitable for wood: high-speed, alloy and carbon. For the processing of metal, plastic, ceramics, stone-like materials, hard alloys, diamonds, elbor, and mineral ceramics are used.

Steel for wood cutters

1. For cutting wood, the following grades of tool steels are used: U-9-A, U-8-A, U-7-A, XV-5, 9-XC, KhG, KhVG.
2. High speed steel can be normal performance. These are the brands R-18, R-6-M-5, R-9, R-12, etc. High performance metal alloyed with vanadium, cobalt, molybdenum and tungsten. These are the brands R-6-M-3, R-18-F-2-K-5, R-9-F-2-K-10, R-9-F-2-K-5, etc.

Note!
If the cutter has soldered teeth, this does not always mean that they are made of carbide.
It can also be high speed steel.

Tooth geometry

By design, the cutters of the cutters are divided into sharp-sharpened (pointed) and backed.

1. For sharpened teeth, the back surface area (width n) adjacent to the cutting part is a plane. Such incisors are sharpened along the back surface. However, if necessary, you can sharpen them along the front edge.
2. For backed cutters of shaped cutters, the back surface has the form of an Archimedes spiral. Its processing is technically very difficult. Therefore, such teeth are sharpened exclusively along the front edge.

Each tooth is a separate incisor.

He has standard parameters: back (a) and front (y) angles, the area of ​​​​the surface to be sharpened (n), the slope angle (l).

1. Site n is the area of ​​the back surface of the cutter, which is ground during turning. In this place, the teeth wear out the most, their size affects the friction force between the cutter and the workpiece. Because of this, this surface should be maintained within the normalized range.
2. The leading edge angle (y) is measured between the tangent to the leading edge and the cutter radius.
3. The basic back angle (a) is measured between the tangent to the back edge at the normalized point of the main sawing edge and the tangent to the rotational circle of this point. This angle, when reduced, reduces the friction between the workpiece and the cutter.
4. Additional back angle (a1) not all cutters have. It describes the expanded clearance between the cut surface and the body of the cutter. The instruction speaks of the need to sharpen this gap with a certain wear of the cutter and expansion of the platform n. The purpose of the operation is to reduce friction between the tooth and the workpiece.

1. Based on the direction and configuration of the cutting edge, the teeth are helical or straight. Their slope describes the angle (l) between the tool axis and the developed helical edge.

The value of the angle depends on the type of cutter, the brand of its material and the type of workpiece being processed. When cutting wood, the main front angle of sharpening is selected in the range of 10-20 degrees, sometimes more. The back angle also fluctuates in wide corridor values.

Methods for sharpening "wooden" end mills

End shaped tools for wood can be sharpened by hand using a thin diamond stone. The cost of performing this operation by a specialist is also low.

Manual work

1. The block should be laid on the edge of the workbench. If the cutter has a deep recess, it must be fixed. The cutter should be driven along the already fixed emery.
2. During operation, the bar must be cooled with soapy or clean water.
3. The front part of the cutter is gradually ground off, its edge is sharpened, and the diameter is slightly reduced.

Note!
When the fixture has a removable guide bearing, it must be removed before sharpening.
In an attempt to save time, you can ruin it and the entire cutter.

By changing the position of the copier needle so that its end touches different points of the tooth groove (for example, center, edge), you can change the values ​​of the rear angles a and a1.

Now about sharpening end cutters.

1. For this purpose, the shaped cutter should be placed in such a position that the tooth to be sharpened will be in an exactly horizontal position.
2. The grinding system of the E-90 machine has a ring with graduation. It makes it very easy to position the end cutters strictly horizontally.

1. When a sharpening machine is used that does not include such a device, a square can be used to set the teeth.
2. When the cutter has taken the desired position, you can begin work. It is carried out by shifting the edge of the grinding disk along the edge of the tooth.
   
3. The value of the angle of turning can be changed by shifting the circle vertically or by tilting the spindle with the cutter.

Conclusion

Sharpening is a rather complicated operation. Refers to the process should be extremely careful. After all, the further efficiency of work with wooden blanks. The video in this article will continue to acquaint you with the nuances of sharpening.

The cutting tool becomes dull sooner or later. If it is disposable, then there is only one way out - to the landfill. But the cutting edge of expensive devices can most often be restored. in this article we will tell you how to give them a "second youth".

Different cutting tools require a differentiated approach when sharpening. Today we will talk about the restoration of chisels, planers, wood cutters and metal drills.

Sharpening chisels and planers

Lead in working condition a chisel or a planer knife is not so difficult. The sharpening procedure consists of only two stages. When working on sharpening tools, you will need a conventional grinder. A chisel or planer knife for soft woods is sharpened at an angle of 250 °. For hard rock– 350°. When sharpening, you must constantly maintain a given angle, which is not so simple. To simplify the task, special devices for sharpening chisels can be used, allowing you to work in the range from 25 to 35 °. To prevent overheating, periodically cool the instrument in water.

Do not immediately grind the edge of the iron until the cutting part appears. When bringing its thickness to half a millimeter with a square, check that the axis is perpendicular to the cutting edge. Final sharpening is best done by hand or on a low-speed water-cooled grinder, bringing the tool to the required sharpness of the cutting edge.

When sharpening a round chisel with an outer edge, the tool moves along the bar from edge to edge along the entire length of the stone, describing the "eight". Burr with inside the groove, which is necessarily formed during sharpening, is removed using a shaped whetstone. The final sharpening of the cutting edge is carried out sandpaper varying degrees of graininess.

Sharpening cutter for wood

For sharpening shaped end mills, it is not necessary to have special devices. It is enough to have a diamond bar laid on the edge of a table or workbench. The cutter is sharpened by holding its front surface along the bar, previously cleaned of resin residues, dirt and dust with a solvent.

If there is a guide bearing, it must be dismantled before sharpening. An attempt to save a couple of minutes will result, if not in its deformation, but, quite possibly, in a damaged cutter. In the process of sharpening, the bar is slightly wetted with water, and after completion of work it is wiped dry. As the front surface is ground down, the edge of the cutter will sharpen and its diameter will decrease slightly.

When sharpening tools, you should use whetstones of different grain sizes, depending on the desired end result and the cleanliness of the surface to be treated. When sharpening incisors to maintain symmetry, a multiple number of movements is performed with equal pressure. Depending on the material from which the cutter is made, instead of a bar, abrasive paper mounted on a strip of steel or a wooden lath can be used.

If you have a low-speed grinder at your disposal, then installing the appropriate abrasive wheel can negate manual labor.

Sharpening a drill for metal

Over time, drills become dull and many simply throw them away, buying new ones. However, almost always the drill can be given a "second chance" and extend its life. To do this, it is enough to process a dull surface on a grinding wheel.

Before starting work, stock up on a container of water into which the drill will be dipped from time to time to avoid overheating. Sharpening is carried out sequentially and begins with the processing of the back surface, gently but tightly pressed against the surface of the grinding wheel until a regular cone is formed.

After that, its cutting part is sharpened and the final finishing of the back surface is carried out. During sharpening, you must constantly monitor the jumper at the tip of the drill. For drills with a diameter of 8 mm or less, it should not exceed 0.4 mm. For large samples, the size of the bridge varies from 1-1.5 mm. Keep in mind that drilling does not produce a tip, but the sides of the drill!

electric grinder

Structurally, electric grinders are extremely simple.

They consist of induction motor, grinding wheels and casings. Having transferred the conversation to the plane of choosing a specific manufacturer and model, it should be noted that if you plan to buy a device for personal purposes, then the brand is not decisive. Such equipment is included in the network for a short time and has a rather large resource. The price of a sharpener directly depends on its diameter.

The larger it is, the more expensive the device. When inspecting an electric grinder before buying, try to move the shaft. If it not only rotates, but also “walks”, discard it and choose further. Of course, it is best to include a sharpener in the network, but not every store will meet you halfway in this matter.

Electric grinders or grinding machines are divided into three groups:

1. High-speed sharpeners equipped with interchangeable holders for various kinds tool.
2. Highly specialized machines designed for a specific tool (for example, drills).
3. Low speed water cooled machines.

If high-speed sharpeners spin up to 3000 rpm, then such machines rotate at a maximum of 150 rpm and can sharpen any cutting tool. Low speed and water cooling ideal conditions for a quality cutting edge.

The cutter can work productively only under the condition correct operation. If the work is carried out with correctly assigned milling modes, the cutter can machine a large number of blanks before it becomes noticeably dull. However, if you continue to work with a noticeably dull cutter, the cutting force will increase dramatically, which will cause an increase in friction, rapid further dulling and even breakage of the teeth of the cutter.
Sharpening a normally dull cutter requires relatively little time and does not significantly reduce the size of the tooth. Sharpening a very blunt cutter is a long, laborious operation, you have to remove a fairly large layer of metal, so the cutter does not need to be brought to severe bluntness.
Especially it is necessary to monitor the condition cutting edges and timely sharpening of expensive cutters made of high speed steel and equipped with hard alloy plates.

Sharpening cylindrical cutters with pointed teeth

Cylindrical cutters with pointed teeth are sharpened along the back surface of the tooth with a cup circle (Fig. 332), while maintaining a predetermined rear angle.

When sharpening, the cutter is put on a mandrel installed in the centers of the grinding machine. The axis of the cup circle is set at an angle of 1 - 2 ° to the axis of the cutter, so that the circle touches the cutter being sharpened with only one side (Fig. 332, c).
If the axes of the cup circle and the cutter being sharpened are located in the same horizontal plane (Fig. 332, a), then the rear angle α at the cutter's tooth will not work. To form a rear angle, the cup circle is placed below the axis of the cutter being sharpened by an amount H(Fig. 332, b), which is determined from right triangle with side and angle α:

Angle α should be selected according to Table. 35.
The position of the cutter tooth during sharpening is fixed with a special stop (Fig. 332) in the form of an ordinary spring steel bar. The stop that supports the tooth being sharpened should be set very close to the cutting edge. It also serves as a guide when sharpening cutters with helical teeth.
When sharpening the back surface of cylindrical cutters with disk circles, a concave chamfer is obtained on the tooth, which weakens the tooth blade and accelerates their wear. Cup wheels when sharpening give a flat chamfer (ribbon), which ensures greater durability of the cutters; for this reason, sharpening cutters with disc wheels is not recommended.

End mill sharpening

sharpening main cutting edge the tooth of the face cutters is made along the back surface, similar to the sharpening of cylindrical cutters with pointed teeth (Fig. 333, a).

At sharpening the secondary cutting edge tooth (Fig. 333, b), first, the cutter is set so that its auxiliary cutting edge is in a horizontal position. Then the axis of the cutter is rotated in the horizontal plane by the value of the auxiliary angle in the plan φ 1 and at the same time tilted in the vertical plane by the butt clearance angle α 1 . The sharpening of the front surface on the auxiliary cutting edge is carried out by the side surface of the cup wheel. The cutter is installed so that the secondary cutting edge is facing upwards, and the cutter axis is tilted in a vertical plane by the value of the front angle of the secondary cutting edge.

Sharpening end mills

main cutting edge end mills (Fig. 334) is made similarly cylindrical cutters the end surface of the cup circle when installing the end mill in the centers.

Sharpening the back surface on secondary cutting edge it is made like end mills with a cup circle. The cutter is fixed with a tapered shank in the socket of the cartridge.

Sharpening of disk cutters

Sharpening the back surface on cylindrical edge disk cutters are produced like cylindrical cutters with a cup circle.
The sharpening of the rear surface of the end teeth is carried out similarly to the sharpening of the teeth of the auxiliary cutting edge of the end mills. The sharpening of the front surface of the end teeth is carried out similarly to end mills. The teeth to be sharpened are directed upwards, and the cutter axis occupies the position:
a) vertical - when the cutter has simple teeth,
b) inclined - when the cutter has multidirectional teeth, and the angle of inclination of the cutter axis in the vertical plane is equal to the angle ω of the inclination of the cylindrical cutting edge.

Sharpening cutters with backed teeth

The teeth of the cutters are sharpened along the front surface. On fig. 335, and a diagram of the installation for sharpening a tooth with a rake angle γ equal to zero (radial front surface) is given, and in fig. 335, b - with a front angle γ greater than zero. Value H 1 shift of the grinding wheel from the center of the cutter is determined by the formula:

The amount of layer removed during sharpening for all teeth must be the same in order to avoid runout of the cutter. If one tooth has a smaller layer removed than the others, it will be longer, will remove chips of a larger section and will become dull sooner. Sharpening of milling cutters on the front surface is carried out with a disk-shaped circle.
When sharpening, make sure that the front surface is radial, as shown in fig. 336, a (tooth 3 ). If the front surface has an undercut (tooth 1 ) or, conversely, a negative rake angle (tooth 2 ), the tooth profile will be distorted and will cut the wrong contour in the workpiece. The position of the cutter tooth during sharpening is fixed with a stop, which should be adjacent to the back surface of the tooth being sharpened.

So that after sharpening the cutting edges have minimal runout, it is recommended to sharpen using a copier that has the same number of teeth as the cutter being sharpened (Fig. 336, b).

Sharpening prefabricated cutters (milling heads)

The cutter blade has more sharpening elements. In addition to the rear corners, it is necessary to sharpen: the main corners corner edge in plan view φ and transitional edge φ 0 , auxiliary angle in plan view φ 1 and section of transitional edge f 0 . To ensure sharpening of each corner in the plan, the cutter takes a position corresponding to this angle (Fig. 337). Sharpening can be done on special grinding or universal grinding machines.

When sharpening to special machines cutter 1 is inserted using its shank or a put on mandrel into the head 2 in a horizontal position (Fig. 338). Head 2 can be rotated about the vertical axis. The cutter can be rotated around its axis using the handwheel 3 and is fixed in the desired position with the help of a stop. After sharpening one tooth, a transition is made to the next by turning the cutter around its axis.

On fig. 339 shows the position when sharpening the cutter on a special grinding machine. First, the ends of the plates or knives are compared (I), then the plates are aligned along the cylindrical edges (II). To form rear corners, the head with the grinding wheel is tilted and fixed in this position (III); to obtain plan angles, the head with the cutter rotates about the vertical axis (IV, V, VI). The complexity of such sharpening is high and ranges from 3 to 12 hours, depending on the degree of blunting (removal value), the number of teeth and the diameter of the cutter.

It should be noted that the wear of the grinding wheel during sharpening by the machine mechanism is not compensated. Therefore, from sharpening one element of the first tooth to sharpening the element of the same name of the last tooth, a known wear of the grinding wheel accumulates. To eliminate the runout of the elements of the teeth that occurs during the wear of the grinding wheel, it is necessary to introduce an additional finishing pass, which increases the complexity of the operation.
On a universal grinding machine the cutter is sharpened in the centers (see Fig. 337). Due to the fact that the mounting holes, i.e., the mounting bases of the cutter, are not used in this installation, the error in the alignment of the sharpening of the cutter cutters increases.
Since prefabricated cutters are the main tool for high-speed cutting methods, the laboriousness of sharpening cutters could be a serious brake on the introduction of high-speed milling. Therefore, in the process of mastering high-speed milling, the sharpening process was redesigned in order to reduce its labor intensity. For this, a method was developed, tested and implemented for sharpening prefabricated cutters with dismantled cutters and plates and their subsequent installation using a template.
Before sharpening, insert knives are removed from the body and usually sharpened as a set. On fig. 340 shows a special rotary device for this purpose, which sharply reduces the complexity of sharpening. The device is installed in the centers of the universal grinding machine. After sharpening one element, the fixture with a fixed set of teeth is rotated to a predetermined angle and the other element is sharpened.

After sharpening is completed, the cutters are installed in the head body using different kind templates (Fig. 341, a - e). Checking the collected milling head beating should be done with an indicator template (Fig. 341, e).

Finishing of carbide cutters

When sharpening with a grinding wheel, the carbide plate heats up unevenly, as a result of which tiny cracks may appear on its surface. Cracks in the process of cutting increase and can be the cause of chipping of the tooth during operation.
One of the goals of finishing is the removal of a defective layer with cracks. The second task of finishing is to increase the surface finish of the cutting edge, which is necessary to reduce friction and wear of the tooth, as well as (increase the purity of the machined surface. The third task of finishing is to eliminate blockages on the surface of the cutter teeth and give them a more correct geometry.
Finishing of cutting surfaces is carried out on special finishing machines with cast-iron disks or manually with a weak pressure of a cast-iron whetstone. Best Results finishing are obtained at the speed of the finishing disk in the range of 1.0-1.5 m/s. For finishing, boron carbide paste with a grain size of 170 - 230 is used.
When manually finishing, it is necessary to observe the correct position of the touchstone in relation to the cutting edge and the correct movement of the touchstone. First, the front and rear surfaces are brought, then finishing (edging) chamfers are formed: for this, the plane of the touchstone is set at an angle of 45 ° to the front surface, and several passes along the cutting edge are made with a low pressure touchstone. It takes 2-3 seconds to form a bordering chamfer. for every knife.
Boron carbide is a strong abrasive. With a cast iron whetstone with boron carbide paste, wear holes can be removed on the teeth without removing the cutter from the machine, which is very important when high-speed milling small workpieces with short cutting periods.

2016-11-04

Sharpening cutters - hard work requiring special training and equipment. The geometry of the cutting edges has a curvilinear structure - this is what main feature process. The grinding wheel must follow exactly the contour of the cutter's sharp teeth in order to maintain its shaped profile.

• The backed teeth are sharpened along the front surface.
• Sharply protruding teeth are processed along the back wall.
• Slitting and cutting cutters are sharpened on the front and back sides.

How to sharpen cutters?

Can be sharpened manually or with grinder for cutters.

Rice. one .

The machine provides synchronization different types movement and fixation of the cutter. For example, to sharpen end mill, it is necessary to combine translational and rotational movements, while maintaining a uniform pressing force of the tool to grinding wheel. Great importance has a rotation speed, abrasive grain size, its material.

• Electrocorundum abrasive wheels are suitable for sharpening milling cutters for metal and wood (the material of manufacture is high-speed or tool steel of the “Standard” class).
• Elborovy (CBN) circles sharpen cutters from high-speed steel of increased productivity.
• Diamond (PCD) and silicon carbide wheels are used to sharpen the teeth of carbide cutters.

It is important to take into account that strong heating reduces the hardness of abrasives and leads to a partial loss of cutting properties. Below is a table of thermal stability of the main materials used for the production of abrasive wheels.

Rice. 2.

To cool the grinding tool during operation, water alone will not be enough - the machine will rust. Masters advise adding soap to water and soda ash, nitrite, sodium silicate, etc. - electrolytes create a protective film on the surface of the grinding wheel.

There are over 20 grinding wheel configurations for sharpening milling tools. The rear planes of the incisors are ground with disk-shaped or cup-shaped circles, the front ones - with flat or disk-shaped ones.

Rice. 2.1

Automated sharpening modes

It is impossible to sharpen carbide tools in "hard" modes of operation of the machine - chipping of the edge of the teeth is possible.

The average circumferential speed of a grinding wheel for processing hard alloys should not exceed 10 - 18 m / s. This means that for a circle d 125 mm, 2700 rpm is the maximum rate of engine rotation. For more soft materials it is enough not to cross the threshold of 1500 rpm.

Milling cutter sharpening technology on the machine

The cutter is fixed in its original position, then the machine is turned on and the tool is slowly brought to the grinding wheel (until it sparkles). There comes the moment of setting the thickness of the removed metal layer, usually not higher than 50 microns and not less than 25 microns.

Sharpening is done on each tooth separately. The needle of the machine must constantly be in contact with the surface of the cutter, start sharpening by placing the needle in the tail groove of the tooth. The loan turns on the machine and, gradually retracting the spindle with the cutter, perform the procedure.

The skill of a professional lies in maintaining a uniform sharpening course on all cutting edges. The same movements will need to be repeated several times for each tooth.

Different types of cutters require different movements.

How to sharpen a cutter by hand?

A shaped end mill for sticky materials (wood) can be sharpened by hand without resorting to expensive equipment. You will need:

• work table and plank in steel or hardwood;
• diamond bar;
• abrasive wheel;
• solvent;
• water with soap or alkali;
• sandpaper.

Rice. 3 .

The diamond bar is fixed on the edge of the table, moistened with soapy water. The cutter must be freed from the bearing (if any), cleaned of residues tree resin. The size of the front angle of sharpening varies in the range:

• 10 - 20 ⁰ for wood cutters;
• - 5 - 0⁰ for tools for metals (mainly for steels).

The range of the sharpening angle of the back surface is wide and not limited by the indicators.

Sharpening is done with smooth movements on a diamond bar.

It is necessary to try to make the same number of movements of the cutter along the bar with the same pressing force. As the cutting edges sharpen, the graininess of the abrasive decreases, the final stage of processing can be done with sandpaper.

The result of sharpening is evaluated visually using a magnifying glass or kerosene. The teeth should not contain even small notches and cracks. To detect microcracks, the surface of the cutting edge is moistened with kerosene - kerosene will show through more in the area of ​​the crack. Notches and micro-cleavages are determined by eye or through a magnifying glass.

If you succeed with proper quality, and you know how to use the tool carefully, then the need for sharpening comes much later than in cases with low-quality products. Big choice high-quality cutters (about 20 types) are always available in the Rinkom store. It is convenient to choose and order tools of the widest profile on the Internet, today it is not dangerous and modern.

Sharpening cutters is an operation to restore cutting properties that have been lost as a result of tooth wear.

The modern equipment that our company uses allows us to sharpen cut-off cutters with perfect accuracy:

• when sharpening cutters, like any other tool, we observe all the necessary parameters;

• provide maximum amount tool regrinding in the future;

• provide best performance when processing materials, lack of chips, increase in the service life of the cutter between sharpening.

A well-sharpened milling cutter increases its durability, which significantly reduces consumption. cutting tool. If you have been operating the cutter for quite a long time or are just planning to use it, then remember that the amount of cutter wear should not exceed the established optimal values, which are taken as the blunting criterion. In order to keep the cutter in its almost original form, it is necessary to monitor the condition of the cutting edges and, of course, sharpen the cutter in time, trying to prevent too much wear or breakage of the teeth.

As a rule, sharpening of a disk cutter is carried out on universal grinding machines. In order for the sharpening process to take place correctly, it is necessary to comply with the existing and introduced certain standards for allowable runouts, established quality assurance for cutting edges and surface quality.

Our company offers you a job High Quality. Turning to us, you turn to highly qualified professionals in their field who approach the performance of their work with all responsibility.

Sharpening cutters with us will ensure a long life and performance of your tool, ensure reliability of operation, since a dull cutter is very dangerous! Keep this in mind when performing a specific task for which you may need this tool. And in case of problems or approaching the end of the resource cutting discs- contact our company.

Rules for accepting disc cutters for regrinding

1. To carry out sharpening of disc cutters, an "Agreement for the processing of customer-supplied raw materials" must be concluded between the customer and the contractor.

2. Cutters are accepted only if there is an invoice form M-15 from the Customer, in which it is necessary to indicate the contract number and the range of disk cutters.

3. When handing over cutting disc cutters for regrinding, the Customer must receive from the Contractor an “Inspection Order” signed by the Contractor, which indicates the cost and deadline for the work.

4. Receipt of cutters is carried out only by proxy.