Sharpening milling cutters


Finishing operation of the manufacturing process of the cutter is its sharpening.

With its help achieve the desired geometry of the teeth. During the subsequent operation of the inevitable wear of teeth of the cutter, so to improve its operation need periodic sharpening and to check the status of the cutting parts.

the Resistance is increased if the sharpening was done correctly. As a consequence, reduced the cost of cutting tools. It is desirable to prevent wear of the cutter above the criterion of blunting, as it leads to the destruction of the teeth and excessive wear of the tool.

For sharpening cutters use specially-grinding and universal grinding machines (for example, ЗА64). To get the right angles on the cutting edges of the tool can only be correctly selecting the appropriate grinding wheel and sharpening. As a result, the cutting properties will be high, and the surface — quality. Cutters of steel, containing cobalt, and vanadium, in contrast to similar steel R18, shown in the process of sharpening is not very good sanding behaviour and the formation of burn marks.

Screw and the pointed teeth are usually treated on a universal grinding machine. The tooth via the rear disk or Cup grinding wheel. The Cup wheel, tilted at a small angle (1-2°) to the axis of the cutter, it applies to only one side. This tilt contributes to the formation of the rear corner of the tooth, fixed focus. The rear surface tooth cylindrical milling cutters get a little more concave when sharpening grinding wheel. Changing the diameter of the disc, reduce the resulting error of sharpening.

Cup grinding wheel (end plane) treated steel end milling cutter with inserts made of hard alloys, not looking at the main plane. Installing auxiliary cutting line horizontally, sharpen auxiliary rear surface. After that, the cutter is placed in accordance with the geometry of the prong. Edge of the disc or end disc surface grinding wheel to sharpen the front surface of the teeth, in compliance with the required geometrical parameters of the angles.

 

universal grinding machine(for example, В3125 cutters d from 14 to 50 mm) we will be able to grind helical teeth on both sides. Main and auxiliary surfaces are fixed and sharpened the butt end of Cup circle.

the Main surface of the disc cutter teeth to sharpen the Cup grinding disk similar to the process of grinding cylindrical or endnote. The rear auxiliary is the same as at the end.

For sharpening the cutter with the simple teeth of a vertically, obliquely, with bi-directional teeth. The axis is inclined at an angle of the main edge.

One of the anterior surface have to sharpen milling cutters with relief teeth. The error of the angle of the front plane should not exceed ±1°, otherwise, the shaped profile will be distorted.

the Smooth part of the Cup disk you can sharpen straight grooves, and conical screw. For accurate sharpening used copier with the same number of teeth. It is not necessary to sharpen relief teeth have wear on the rear of the plane more than 0.5-0.75 mm, as then you will need to grind the entire profile.

 

Sharpening plug-in plate mills the collection is carried out, securing the tooth in the grip of a three-pivot universal grinding machine or grinded with armrest. Below the cutter is not cracked in a vise, insert between them a rubber gasket. Teeth end milling cutter to sharpen in a single setup. In this method, the wear of the grinding wheel used has little effect on accuracy. For the smoothness of the ground surface of the cutter, the circle rotates in the direction from the base to the cutting edge. In the industry of teeth of face mills are sometimes treated without analysis of plates. Machines for grinding tools made of hard alloys also sharpen end milling cutter of composite diamond discs ASO 8-10 B1 100%.

 

 

Finishing after sharpening is needed to achieve the surface smoothness of the cutting edges above the permissible values of roughness. The debugging process is needed to eliminate possible burn marks, cracks or other insert errors that occur during tool sharpening. Finishing mills is carried out mainly by processing of diamond or fine carbide-silicon abrasive wheel.

 

industrial machines adjusted cutters with cutters or mineral ceramic or hard alloy. For example, the machine SV-20 versatile plate is treated in a closed cassette that protects against dust; the reference plane is adjusted also in magazines with the help of diamond disc for surface grinding machine. Processing diamond circle will increase tool life from plastic material and with great wear 2-5 times (in directly proportional dependence on cutting speed), when compared with discs made of silicon carbide. But it is not advisable when working with steels of high strength, titanium and hard alloys, especially at low cutting speeds and also with brittle hard metal. In these cases it is ineffective, it may even reduce the durability of the cutting plane of the tool because of its cracking.

For sharpening and finishing of carbide cutters use diamond wheels, for example, of the following types: AT, AIT, ABC,APV, ASHP and others. The result is good surface quality and increase tool life by almost two times. The best among the ordinary abrasive grinding wheel is made of composite materials.

 

After sharpening definitely are checking the correctness of all geometric, angles of cutting edges, surface smoothness and runout. The runout of the cutter is fixed in the device (the center in the headstock), control of the indicator during its processing. To control the internal (landing) the hole is fixed on the mandrel vertically or horizontally. The runout of working parts of the cutter shank in the form of a cone or cylinder check special device or a prism. Also control the runout of the face of the teeth, a cylindrical surface reference face and edge angles. Control quality finishing and sharpening is carried out visually using a magnifying glass, magnifier, microscope. Are not allowed burrs, chipping, dings on the cutting edges. Cracks in the teeth of hard alloy can be seen through a magnifying glass, or when sanding plate, drenched in kerosene.

 

 

And at the end an advice: how to sharpen the cutter by yourself without machines and special devices.

Remove from the cutter bearing, cleaned by solvent contamination. On the edge of a bench or table, place diamond bar, which will drive the front plane. Periodically changing the bar on the other with a different grain to improve the quality of the sharpening. If you sharpen the cutter for milling-hobbing machine, try to keep the symmetry of edges, motion carried with a uniform pressure. The bar from time to time slightly wetted with water. At the end of work, dry it with a cloth or any cloth. You can use sandpaper instead of the bar depending on the material from which made the cutter. The paper should be glued or attached to the surface (wood, steel). For sharpening you can also use a grinding stone by rotating it at low speed.

 

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