Determination of tooth pitch and number of simulta

The design of broach includes the determination of broaching allowance, the design of chip holding groove, the determination of chip dividing groove form, the determination of tooth pitch and the number of simultaneous working teeth, the determination of tooth lift and front and rear angles, etc. In practice, we found that under the premise that the design of chip holding groove and the determination of the form of chip dividing groove are reasonable, the tooth pitch and the number of simultaneous working teeth have a great impact on the broaching quality

we know that the smaller the tooth pitch is, the more the number of working teeth is, the more balanced the cutting process is. But the premise of reducing the tooth pitch is to ensure that the broach has enough chip space, and at the same time, too many working teeth will also make the broaching force too large. After years of practice in our factory, we have made the following preparations: it has been proved that when conditions permit, when the number of teeth of the broach working at the same time is 4 ~ 6, the broaching effect is ideal; When the workpiece is short, it can also achieve satisfactory results by ensuring that the number of teeth working at the same time is 3. In the broaching process, the number of simultaneous working teeth of the broach changes, and the minimum number of simultaneous working teeth is one tooth less than the maximum number of simultaneous working teeth. The change of the number of simultaneous working teeth changes the broaching force and destroys the balance of the broach work. Therefore, when determining the tooth pitch, it is also necessary to ensure that the number of working teeth does not change during most of the broaching process, so as to better ensure the broaching quality pointed out in the report

now our factory processes 150.37 Quadruple teeth (broaching length 72, see Figure 1) and 150.37 The design of round hole broach with double teeth (broaching length 43, see Figure 2) and diameter 32.60+0.025 is explained

Figure 1 Figure 2

when starting to design the circular broach of these two gears, in order to facilitate the manufacture, management and use of the tool, it is decided to use the same broach for the two gears, with coarse tooth pitch t=11 and machining 150.37 When, the number of teeth working at the same time z=43/11=3.9, that is, 90% of the broaching time is 4 teeth working at the same time, and 10% of the broaching time is 3 teeth working at the same time; Broaching 1 realizes the combination of online and offline, and the connection between steel production and steel use 50.37 The number of teeth working at the same time z=72/11=6.5, that is, 50% of the time is 7 teeth working at the same time, and 50% of the time is 6 teeth working at the same time. After use, the effect is not ideal. 150.37. The broaching effect is 150.37% The broaching effect of is better, but there are slight scale thorns on the processing surface, and the broaching quality 210 is unstable. The broach needs to be repaired frequently, which affects the service life of the broach. The reason is that the tooth pitch is not reasonable, broaching 150.37 Although there are many teeth working at the same time, the actual number of teeth working at the same time changes frequently, and the broaching process is unstable. Therefore, we redesigned the broach and used broaches with different tooth pitches for two parts. For 150.37, If the tooth pitch of rough broaching is taken as t=9, the number of teeth working at the same time z=43/9=4.8, that is, 80% of the broaching time is 5 teeth working at the same time; For 150.37, If the tooth pitch of rough broaching is taken as t=14, the number of simultaneous working teeth z=72/14=5.1, that is, the number of simultaneous working teeth is 5 in 90% of broaching time (see Figure 3 for the schematic diagram of the number of simultaneous working teeth). This makes the broaching process more stable. After improving the design, the broaching quality of the two kinds of gears has been greatly improved, and the quality is stable, and good results have been achieved

figure 3

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