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Îœm root circle tooth profile error ff
Μm 5° +2.8 +5.9 10° +5.0 +10.7 15° +7.7 +15.4 20° +10.0 +20.1 Slotting tool parameters m=2.5mm, a=20°, z0=30°, ae=6° in the gear During processing, sometimes the work piece material has a large plasticity, and the use of the standard front and back corner cutting tools is not easy to achieve the required tooth surface finish. At this time, the method of increasing the front angle of the pinion cutter can be used. When machining 38CrNiMo ALA and 40CrNiMo A gears, deeper scratches are produced on the tooth surfaces when using the standard front and back corner cutters, and scratches are not easily eliminated after the grinding and grinding processes. At this time, the use of an injecting knife with an increased front and rear angle (ae=9°, g=15°) is performed, and the tooth surface finish can be stabilized to 5 to 6 grades. When the precision of the gear is required to be high, in order to avoid the excess error of the profile error caused by the increase of the front and rear corners of the cutting tool, the following solutions can be taken: (1) Correct the tooth profile angle of the pinion cutter. In Table 1, the tooth shape error at the circle of the pinion cutter is greater than the tooth shape error at the top circle. If the tooth profile angle of the pinion cutter is appropriately reduced, the tooth profile error at the root circle can be reduced, thereby reducing the total teeth. Shape error. Using this method requires repeated trials to minimize the profile error. 2 If the method of correcting the tooth angle can still not reach the required tooth profile accuracy, the actual tooth profile error of the pinion cutter can be calculated, and then the grinding wheel of the grinding tooth shape can be specially dressed to make the grinding The tooth shape error of the cut-out cutter is minimal. This method is generally used when there is a special requirement on the accuracy of the tooth profile. 4 The special sharpening of the rake face of the cutting tool To increase the rake angle of the side cutting edge of the cutting tool, you can also grind the rake face of the cutting tool with a special sharpening method. For ordinary modular pinion cutters, the sharpening method shown in Fig. 2a can be used, so that the top edge rake angle and side edge rake angle of the pinion cutter increase at the same time. Grinding wheel consists of two sides of the conical surface and the middle of the cylindrical surface, the cylindrical surface width is equal to the pinion blade thickness, the intersection of the two sides of the cone surface and the rake face of the pinion cutter hyperbola, the double The curve is very close to the involute theoretical tooth shape of the pinion cutter, so the tooth shape error of the grinded cutter is extremely small. For the larger size of the pinion cutter, the sharpening method shown in Fig. 2b can be used to grind out the top edge rake angle and side edge rake angle of the pinion cutter. Due to the complex handling of special sharpening methods, they are used only on special occasions. 
(a) 
(b)
In cutting, the useful life of the tool is limited by the wear of the main cutting edge. There are many factors that affect the wear of the tool, including the mechanical physical properties of the workpiece material and the tool material, the structure and geometry parameters of the tool, the cutting conditions and the amount of the tool. For sizing, the rake angle of the cutting tool has a direct effect on the tool's durability and tolerance. 1 The geometry of the pinion cutter The rake angle of the top edge of the standard pinion cutter g = 5°. The rake face of the pinion cutter has a concave conical surface, thus forming a side rake angle. The rake angle of the side edge of the pinion cutter should be measured on a section perpendicular to the projection of the cutting edge on the base surface (ie, the NN section tangential to the base cylinder shown in Figure 1). The rake gyc at any point A on the side edge is calculated as tangyc=tangsinay where ay is the involute pressure angle at any point A on the cutting edge and cosay=rb0/ry. The rake angle at the point is not equal, and the rake angle of the side edge near the top circle is larger, and the rake angle of the side edge near the root circle is smaller. Since the rake face of the pinion cutter is a conical surface, the side edge forms a certain blade angle. The angle of inclination of the cutting edge is different. The inclination ly of the blade at any point A is tanly=tangcosay. For the cutting edges on both sides, the rake angle is the largest at the top circle, and the angle is the smallest before the side edge at the root circle. The angle is the smallest and the blade angle is the largest. The blade inclination can play a role in increasing the front angle of work. For standard cleavers (eg m=2.5mm, a=20°, z0=30, g=5° trowel), the rake angle at the top circle is gac=2°36′. Side edge rake angle gfc=0°13'. Because the side rake angle is very small, it has a certain influence on the cutting performance. 2 Increase the influence of the rake angle of the tool on the durability of the tool. When machining steel gears, increasing the rake angle of the tool will not only improve the finish of the tooth surface, but also increase the durability of the tool. If the rake angle of the cutting tool is increased from 5° to 15°, the tool life can be 134.8 minutes under the machining conditions of m=2.5mm, a=20°, z0=30, z1=42, ae=9°. Increased to 252 minutes (88% increase), which is 4 times the durability (62.3 minutes) of the standard pinion cutter (ae=6°, g=5°) (increases 404.7%). After increasing the rake angle to 15°, the rake angle of the side edge can be significantly increased (the front edge angle of the side edge gac=10°39′ at the top circle, and the front edge angle of the side edge gfe=7°06′ at the root circle). Significantly improve the tooth surface finish. 3 Increasing the influence of the rake angle of the shaper blade on the profile error After increasing the rake angle of the shaper blade, the profile error of the shaper blade will increase. Therefore, it is necessary to analyze and increase the size of the profile cutter according to the accuracy requirements of the gear being machined. The feasibility of the front corner. For m=2.5mm, a=20°, z0=30 for the pinion cutters, when the apical angle ae=6°, the rake error at different rake angles is shown in the table (the values ​​in the table are the pinion cutters. Tooth angle corrected tooth profile error). It can be seen that when the rake angle of the pinion cutter increases to 15°, the tooth profile error is quite large and cannot be ignored. For a large module and a small number of teeth, the resulting profile error will be greater. Therefore, the large rake angle cutter is mainly suitable for machining low-precision gears or for rough machining. Table The effect of the rake angle of the plunging blade on the tooth profile error