A cutter is a type of round rotating cutter. Its cross section always contains a circle, and the shape itself can be any, including very complex ones. There are grooves (of varying depths) or denticles along the circumference. They process the material during the rotation of the cutter. – the process is complex and painstaking. It is important that not only the specialist has a certain level of skill, but also sharpening tool corresponded to the most high requirements. Otherwise, chips, cracks or unsharpened areas will remain on the cutter after processing, which will directly affect the further performance of milling work.
Varieties
Incisors are the most different types– end, end, disk, slotted, cylindrical, groove. And these are not all varieties. They are also divided according to their purpose and are angular, shaped, keyed, for T-shaped grooves. Another division is based on the type of surface being processed:
- for metal;
- on wood;
- on plastic;
- on glass;
- and others.
Sharpening cutters for metal complex due to the large length of the cutting surface. This work is only possible when using special tools. In some cases, you have to grind by hand, but this requires a lot of experience. Otherwise all Previous work will go down the drain. The grooves (teeth) will show nicks, gouges, chips and cracks. The part will have to be ground again, which invariably reduces its size.
A cutter can work productively only if correct operation. If the work is carried out under correctly assigned milling modes, the cutter can process a large number of workpieces before it becomes noticeably dull. However, if you continue to work with a noticeably dull cutter, the cutting force will increase sharply, which will cause an increase in friction, rapid further dulling and even breakage of the cutter teeth.
Sharpening a normally dull cutter requires relatively little time and slightly reduces the size of the tooth. Sharpening a very dull cutter is a long, labor-intensive operation; you have to remove a fairly large layer of metal, so the cutter does not need to be made too dull.
It is especially necessary to monitor the condition cutting edges and timely sharpening of expensive cutters from high speed steel and equipped with hard alloy plates.
Sharpening cylindrical point cutters
Cylindrical cutters with pointed teeth are sharpened along the back surface of the tooth with a cup circle (Fig. 332), while maintaining the specified clearance angle.
When sharpening, the cutter is put on a mandrel installed in the centers sharpening machine. The axis of the cup wheel is set at an angle of 1 - 2° to the axis of the cutter, so that the circle touches the cutter being sharpened on only one side (Fig. 332, c).
If the axes of the cup wheel and the cutter being sharpened are located in the same horizontal plane (Fig. 332, a), then the rear angle α at the cutter tooth will not work. To form a back angle, the cup circle is positioned below the axis of the cutter being sharpened by an amount H(Fig. 332, b), which is determined from a right triangle with side and angle α:
Angle α should be selected according to the table. 35.
The position of the cutter tooth during sharpening is fixed with a special stop (Fig. 332) in the form of an ordinary strip made of spring steel. The stop that supports the tooth being sharpened must be installed 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 disc wheels, a concave chamfer is obtained on the tooth, which weakens the tooth blade and accelerates their wear. When sharpened, cup wheels produce a flat chamfer (ribbon), which ensures greater durability of the cutters; For this reason, sharpening cutters with disc wheels is not recommended.
Sharpening end mills
Sharpening main cutting edge The teeth of end mills are made along the rear surface, similar to sharpening cylindrical cutters with pointed teeth (Fig. 333, a).
At sharpening the auxiliary cutting edge tooth (Fig. 333, b), the cutter is first installed so that its auxiliary cutting edge occupies a horizontal position. Then the cutter axis is rotated in the horizontal plane by the amount of the auxiliary plan angle φ 1 and at the same time tilted in the vertical plane by the end clearance angle α 1 . Sharpening of the front surface on the auxiliary cutting edge is carried out by the side surface of the disc wheel. The cutter is installed so that the auxiliary cutting edge is facing upward, and the axis of the cutter is tilted in the vertical plane by the amount of the rake angle of the auxiliary cutting edge.
Sharpening end mills
main cutting edge End mills (Fig. 334) are produced similarly to cylindrical cutters by the end surface of a cup wheel when installing the end mill in the centers.
Back surface sharpening auxiliary cutting edge It is produced similarly to face milling cutters using a cup wheel. The cutter is secured with a conical shank in the chuck socket.
Sharpening disc cutters
Back surface sharpening cylindrical edge disk cutters It is produced similarly to cylindrical cutters using a cup wheel.
Sharpening the back surface of the end teeth is carried out similarly to sharpening the teeth of the auxiliary cutting edge of end mills. The front surface of the end teeth is sharpened in the same way as end mills. The teeth to be sharpened are directed upward, and the axis of the cutter occupies the position:
a) vertical - when the cutter has simple teeth,
b) inclined - when the cutter has multi-directional teeth, and the angle of inclination of the cutter axis in the vertical plane is equal to the angle ω of inclination of the cylindrical cutting edge.
Sharpening cutters with backed teeth
The teeth of backed cutters are sharpened along the front surface. In 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 rake angle γ Above zero. Magnitude N 1 shift grinding wheel from the center of the cutter is determined by the formula:
The amount of layer removed during sharpening should be the same for all teeth to avoid runout of the cutter. If a smaller layer is removed from one tooth than the others, it will turn out to be longer, will remove chips of a larger cross-section and will become dull sooner. The cutters are sharpened along the front surface using a disc wheel.
When sharpening, you must ensure 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 an irregular contour into the workpiece. The position of the cutter tooth during sharpening is fixed by 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 of prefabricated cutters (milling heads)
The knife of a prefabricated cutter has a larger number of sharpening elements. In addition to the rear corners, you need to sharpen: the main corners corner edge in plan φ and transition edge φ 0, auxiliary angle in plan φ 1 and section of transition edge f 0 . To ensure sharpening of each angle in the plan, the cutter takes a position corresponding to this angle (Fig. 337). Sharpening can be done on special sharpening or universal sharpening machines.
When sharpening on special machines milling cutter 1 inserted into the head using its own shank or a mounted mandrel 2 in a horizontal position (Fig. 338). Head 2 can rotate about a vertical axis. The cutter can be rotated around its axis using a handwheel 3 and is fixed in the desired position using a stop. After sharpening one tooth, the transition is made to the next by rotating the cutter around its axis.
In Fig. 339 shows the positions when sharpening a cutter on a special sharpening machine. First, the ends of the plates or knives are compared (I), then the plates are aligned along the cylindrical edges (II). To form back angles, the head with the grinding wheel is tilted and fixed in this position (III); to obtain plan angles, the head with the cutter is rotated about a vertical axis (IV, V, VI). The labor intensity of such sharpening is high and ranges from 3 to 12 hours, depending on the degree of dullness (amount of removal), the number of teeth and the diameter of the cutter.
It should be noted that the wear of the grinding wheel during sharpening is not compensated by the machine mechanism. Therefore, from sharpening one element of the first tooth to sharpening the same element of the last tooth, a certain wear of the grinding wheel accumulates. To eliminate runout of tooth elements that occurs during wear of the grinding wheel, it is necessary to introduce an additional finishing pass, which increases the complexity of the operation.
On a universal sharpening machine the cutter is sharpened in the centers (see Fig. 337). Due to the fact that mounting holes, i.e., the cutter mounting bases are not used with this installation, the error in the coaxiality of sharpening the cutter cutters increases.
Since prefabricated cutters are the main tool for high-speed cutting methods, the labor intensity of sharpening cutters could be a serious obstacle to the introduction of high-speed milling. Therefore, in the process of mastering high-speed milling, the sharpening process was restructured in order to reduce its labor intensity. For this purpose, 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. In Fig. 340 shows a special rotary device for this purpose, which sharply reduces the labor intensity of sharpening. The device is installed in the centers of a universal sharpening machine. After sharpening one element, the device with a fixed set of teeth is turned to a given angle and begins sharpening the other element.
After sharpening is completed, the cutters are installed in the head body using various kinds templates (Fig. 341, a - d). Checking the collected milling head The runout should be checked using an indicator template (Fig. 341, e).
Finishing of carbide cutters
When sharpening with a grinding wheel, the carbide plate is heated unevenly, as a result of which tiny cracks may appear on its surface. Cracks increase during the cutting process and can cause tooth chipping during operation.
One of the purposes of finishing is to remove the defective layer with cracks. The second task of finishing is to increase the cleanliness of the surface of the cutting edge, which is necessary to reduce friction and tooth wear, as well as (increase the cleanliness 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.
The finishing of cutting surfaces is carried out on special finishing machines with cast iron discs or manually with gentle pressure from a cast iron whetstone. Best results finishing is obtained at a speed of finishing disk in the range of 1.0-1.5 m/sec. For finishing, boron carbide paste with a grain size of 170 - 230 is used.
When finishing manually, it is necessary to observe correct position the whetstone in relation to the cutting edge and the correct movement of the whetstone. First, the front and rear surfaces are finished, then finishing (edging) chamfers are formed: for this, the plane of the whetstone is placed at an angle of 45° to the front surface, and several passes are made along the cutting edge with the whetstone with gentle pressure. It takes 2-3 seconds to form the edge chamfer. for each knife.
Boron carbide is a strong abrasive. Using a cast iron whetstone with boron carbide paste, you can remove wear holes on the teeth without removing the cutter from the machine, which is very important for high-speed milling of small workpieces with short cutting periods.
Milling cutter is a tool used for processing various products. Milling cutters of various types are used, which allow changing external and internal surfaces with the required accuracy. For achievement high performance The cutter must be of high quality - be sharply sharpened. Sharpening of ends, wood, plastic, glass is carried out using special machines and equipment.
Tool sharpening
Sharpening is carried out to restore cutting ability, with operations performed contour-wise and separately.
Cutters received for sharpening are usually pre-ground on a cylindrical surface using a cylindrical grinding machine to eliminate damage, with further sharpening of the back or front of the teeth.
End mills with pointed teeth are sharpened along the back surface with a special disk- or cup-shaped wheel. To do this, install the circle relative to the axis at an angle of 89°, which allows you to achieve the required contact between the contacting surfaces.
When sharpening the back surfaces of end mills, 2 main methods are used:
- polyelement;
- contour.
When using the multi-element method, the cutting edges are sharpened separately. First, the main surfaces of all teeth are sharpened, then the auxiliary and transitional ones.
With the contour method, sharpening is performed sequentially on each tooth in one operation. A single-turn sharpening method is also used, when the cutting edges are processed in one operation. All teeth are sharpened in one revolution and the allowance is removed using a grinding operation.
Types of Tools Used
On industrial enterprises apply Various types tool:
- Cylindrical - for processing workpieces using machines equipped with a horizontal spindle.
- Face - for milling workpieces on machines with a vertical spindle.
- End - for driving ledges, recesses, contours (curvilinear). Used on installations for vertical milling.
- Disc - for driving grooves and grooves on horizontal machines.
- Keyed – for making grooves on machines with a vertical spindle.
- Angular – for milling planes (inclined), grooves, bevels.
- Shaped – when processing shaped surfaces.
To process workpieces, equipment is used that is designed for the following work:
- for metal;
- on wood.
Milling cutters with appropriate equipment are usually produced as sets with mounting dimensions for fasteners of different diameters. In order for the cutter to be used a long period it must always be sharpened, and when carrying out a working operation it is necessary temperature regime, preventing overheating, which reduces their strength characteristics.
Using hob sharpening equipment
When processing workpieces, hobs are most often used.
The characteristics of hob cutters are strictly regulated by GOST 9324-60 and are produced:
- whole;
- prefabricated (welded, plug-in).
Prefabricated hobs (for modules from 10 to 16) are used with insert combs, which are made of high-speed cast steel or forged.
Hobs (for modules 18 to 30) are manufactured by welding and mounting carbon steel teeth on a base.
When using hobs to cut cylindrical gears, the working parts of the tooth wear unevenly.
To increase the service life of hob cutters, a height correction method is proposed by changing the shape of the spatial curve characterizing the working process. The method of axial displacement of the tool is also used, which increases the speed of operations with an increase in the service life of hob cutters.
The process of sharpening backed hob cutters is carried out along the front part, and sharpened ones are carried out along the back surface of the tooth. After finishing the sharpening process, measurements are taken:
- front surface profile;
- circumferential pitch;
- compliance of chip flutes.
Types of equipment used for fixing tools
The equipment used to fasten the tool is divided into 2 types:
- nozzle;
- end
The end equipment is attached using a collet and a chuck, and the attachment equipment is used by installing it on a spindle using a special mandrel.
To fasten the tool, 2 types of mandrels are produced:
- center;
- terminal
Center mandrels are produced with a conical shank, which has dimensions corresponding to the hole in the spindle, and are produced in 2 types 7:24 and Morse taper.
Allowed when used of this type mandrels, install several cutting tools with special rings.
When using a cylindrical end mill, a chuck with a collet is required. Typically, the equipment includes 7-11 collets, allowing you to select the required size for reliable fixation.
Equipment for fixing the workpiece
To carry out the milling process, it is necessary to fix the workpiece, for which the following are used:
- rotary tables;
- vice;
- clamps.
Round rotary tables are used for milling operations on workpieces with a curved surface.
This type of table has a wide range of offsets:
- rotation;
- changing the angle of the table plane;
- Possibility of processing products in a vertical position.
Clamps or clamps allow you to fix products using special elements, which in turn are attached to the table using bolts and nuts. To fix small-sized workpieces, a simple vice with a rotating mechanism is used.
Using Accessories
For fixing parts having cylindrical shape use a three-jaw chuck and special centers, which, with the help of clamps and steady rests, carry out fixation, as well as the use dividing heads. These devices are used to process parts at a given angle during rotation.
The dividing head consists of the following elements:
- housings;
- rotary pads;
- spindle.
A three-jaw chuck is attached to the spindle, designed to fix the workpiece; the other end rests against the headstock. The block can rotate and lock at the required angle. When processing a long workpiece, steady rests are used for fixation.
Sharpening cutters is an operation to restore cutting properties that were lost as a result of tooth wear.
Modern equipment which our company uses allows you to sharpen cutting cutters with perfect accuracy:
- When sharpening cutters, like any other tool, we comply with all the necessary parameters;
- we provide maximum amount tool sharpening in the future;
- we provide best performance when processing materials, no chipping, increased service life of the cutter between sharpenings.
Well-done sharpening of a cutter increases its durability, which significantly reduces consumption. cutting tool. If you operate the cutter sufficiently for a long time or you are just planning to use it, then remember that the amount of wear on the cutter should not exceed the established optimal values, which are accepted as the criterion for dullness. In order to preserve 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 a timely manner, trying to prevent too much wear or breakage of the teeth.
As a rule, sharpening of a disk cutter is carried out on universal sharpening machines. In order for the sharpening process to occur correctly, it is necessary to comply with the existing and introduced certain standards of permissible runout, established quality assurance of cutting edges and surface quality.
Our company offers you the job of High Quality. By contacting us, you are contacting highly qualified professionals who approach their work with full responsibility.
We will provide sharpening of cutters long life and the performance of your tool will ensure reliable operation, since a dull cutter is very dangerous! Keep this in mind if you are performing a specific task that may require this tool. And in case of problems or when the cutting discs reach the end of their service life, please contact our company.
Rules for accepting disc cutters for regrinding
1. To sharpen disc cutters, an “Agreement for the processing of customer-supplied raw materials” must be concluded between the customer and the contractor.
2. Milling cutters are accepted only if there is an M-15 delivery note 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 completing the work.
4. Receipt of cutters is carried out only by proxy.
An operation such as sharpening a wood cutter is not so simple. This process requires certain knowledge and skills.
Buying wood cutters in Kyiv and other cities is now not a big problem. But sooner or later the highest quality of them will become dull, and then it will have to be sharpened. How to do this correctly?
Wood cutter: basic rules for sharpening
The teeth of the product can be completely different. The inclination of these elements can be different and is characterized by the main part of the edge. The parameters for determining the appropriate teeth depend on the tool, as well as the features of the product you choose.
The process of sharpening a cutter can be done without special expensive equipment, since diamond stones of small thickness can be used. In this case, you need to use plain water or a liquid with a soap solution. When the sharpening process comes to an end, you should wash and dry the tool.
First, the cutter must be dismantled. The main thing is that you do not forget to clean it of resins and wood. An ordinary solvent can cope with these tasks.
To effectively solve these problems, you must choose quality materials. If you do not do this, then the work will not bring the desired result.
- you need to use bars with different levels graininess. This setting depends on the material you are going to remove;
- The purity of the base, which you initially determined, plays an important role. Before you carry out the sharpening process, you should make sure that the beam will be of the shape you need;
- symmetry is preserved only if you try to create a configuration similar to the movement of the cutters during the process of sharpening the product;
- if the material of the teeth is quite soft, then replace the beam with abrasive paper, which will provide a perfectly even base;
- the end products are sharpened on the device that is intended for this purpose. The wheel does not spin very quickly, so you will have to buy an abrasive product.
Of course, the process of sharpening a cutter takes a lot of time. However, this resource will pay for itself over time, because you will do your job with maximum effect.
These are the main points that relate to this field of activity. You must take into account all the nuances to achieve maximum results, because all other rules will not provide you with the same effect.
Quick cleaning and sharpening of wood cutters. Or how to sharpen end mill with your own hands: