End mills are often used in daily mold processing. They are often used to process some planes, curved surfaces, grooves and step surfaces. So what processes and sharpening technologies are required for the production of an end mill?
The cutting edge on the round bar surface of the tungsten steel end mill is the main cutting edge, and the cutting edge on the end surface does not pass through the center and is the secondary cutting edge. The workpiece should not be fed axially. Before sharpening, the grinding wheel needs to be checked. If the grinding wheel is found to be jumping, the cylindrical surface is irregular, the fillet is too large, etc., it needs to be trimmed. Generally, the cylindrical surface of the grinding wheel can be trimmed with a grinding wheel dresser (diamond dresser, tooth dresser, etc.), or with a waste grinding wheel with relatively large abrasive hardness. If the side plane of the grinding wheel is not flat, the grinding wheel can be replaced.
Tungsten Steel End Mill End Grinding Technology
Regardless of the number of blades of a tungsten steel milling cutter, the blade end face must first be ground perpendicular to the axis. This is the key to ensure that the highest point of the blade can be in the same plane. The method for grinding the blade end face and checking the verticality of the milling cutter axis is as follows.
Visual inspection. With the help of a flat plate, place the tungsten steel milling cutter with the blade facing down on the flat plate and observe the left and right tilt angles. Then rotate the milling cutter 180° and observe its left and right tilt angles. In the same direction, if the tilt angles observed twice are different, it is necessary to grind until the tilt angles observed twice in the same direction are the same. Then rotate the milling cutter 90° and repeat the above actions to check the other direction.
Calibrate with a square. Calibrate with a 90° square on a flat plate. After placing the milling cutter and the square flat, observe whether there is a gap between the milling cutter and the square or whether the gap is uniform. Then judge the verticality of the milling cutter based on the gap and grind the milling cutter.
Self-calibration. Clamp the tungsten steel milling cutter on the chuck of the drilling machine or milling machine, put a used grinding wheel underneath, select the appropriate speed, turn on the machine tool, then move the milling cutter down, grind on the grinding wheel, and grind according to the end face grinding situation.
Place the tungsten steel milling cutter with a serious gap on the cutting machine, adjust it, and cut out the milling cutter section at one time.
Grind the milling cutter with a three-claw or taper sleeve, clamp it, and adjust it. Grind the end face of the milling cutter with a grinding wheel until it meets the requirements.
Technology of Cross Chip Removal in Tungsten Steel End Mill
If there is no circular groove on the front of the four-blade tungsten steel milling cutter, you need to use the rounded corners of the grinding wheel or on the grinding wheel cutter to re-open the cross groove along the spiral groove direction of the cross of the milling cutter, with a depth of about 1 to 2 mm (too deep will cause cracking, too shallow will make it difficult to grind out the secondary back angle). When grooving, be careful not to let the side of the grinding wheel touch the other cutting edge below (Note: This cross groove has a chip removal function. If it is not opened, the inclination angle of the blade concave to the middle should be increased).
Tungsten Steel End Mill Cutting Edge Grinding Technology
When grinding each blade face separately, take the tip of each blade as the reference, keep the blade tip as the principle, and then grind the front angle (no grinding is required if there is no chipping), back angle, secondary back angle (if a large amount of cutting requires better strength, it is recommended to increase the blade wedge angle in front of the grinding knife) and the blade inclination angle.
The angles to be selected are back angle 6°~8°, (secondary back angle 30°~45°) blade inclination angle 1°~3°. The choice of back angle should be changed according to the hardness of the workpiece. The harder the material, the smaller the angle; the principle of blade inclination angle selection is that all four blades must be concave to the middle, and the blade must not be convex in the middle, otherwise the milled plane will definitely be uneven. Moreover, the more concave the middle of the blade is, the better it is. In fact, all four blades are concave to the middle. The flatter this angle is, the better the roughness accuracy. At this time, the deeper the processing depth (such as greater than 2mm but within the permitted range), the better the roughness accuracy will be, because the entire cutting edge is involved in the cutting, and the surface quality formed is good.
After the sharpening is completed, stand the tungsten steel milling cutter on a platform. If the axis is vertical, all the blade tips can be flush, and the blade angles can be evenly aligned, so that it can meet the requirements. At this time, you can also use a 90° square ruler on a flat plate to calibrate. After laying it flat, observe whether there is a gap between the milling cutter and the square ruler or whether the gap is uniform. Generally, observe the two relatively high feet (the two feet that touch the bottom first). If they are not vertical, grind the higher feet until the two opposite feet are the same height (that is, vertical). At this time, there is a height difference between these two feet and the other two opposite feet, and the milling cutter will swing. At this time, grind the two higher feet down at the same time. Similarly, rotate the milling cutter 90° to observe the verticality of the other two opposite feet, and finally make the four feet touch the bottom at the same time and make the milling cutter vertical. Milling cutter after sharpening.
In manual sharpening, the height and angles of the blade are not easy to grasp. It varies from person to person during training. Just pay attention to grinding a little back angle, but it must be concave in the middle, so that even if the cutting edge is uneven, as long as the tip is at the highest point, it can ensure that the sharpened tool can be milled normally. In addition, if you are not processing the inner cavity, you can also grind the chamfer greater than 0.2mm at the tip to increase the strength of the tip.
Tungsten Send Main Edge (Side Edge) Grinding Technology
If the main edge of the tungsten steel milling cutter is worn, it is necessary to grind it along the spiral line on the grinding wheel (a smaller diameter grinding wheel is better) (it is difficult for beginners to grind it well). However, there is generally a taper after grinding, and the smaller the taper, the higher the operating level.
