JPH0115466Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a shaving cutter for finishing gears.

Shaving is used to correct pitch errors and eccentricity during pre-processing in the gear manufacturing process, performs crowning to create a bulge in the direction of the tooth trace, and is used to smooth rotation of automotive spur gears and helical gears. It is widely used as a finishing method for gears. As shown in Fig. 1, a shaving cutter 1 for performing the shaving has a large number of helical helicals 2 inclined at a predetermined angle with respect to the axial direction formed on the outer circumference, and the tooth surfaces of the helical helical 2 are A configuration in which multiple serrations 3 are formed along the tooth depth direction is common. As shown in Fig. 2, the shaving cutter 1 is engaged with the gear 4 to be cut as if it were a set of screw gears, and if the two are allowed to rotate freely by pushing in slightly, then the The gear 4 to be cut can be shaved by the relative sliding.

By the way, the above-mentioned shaving cutter 1 is used by repeatedly re-grinding it in order to maintain its sharpness in good condition, and it usually wears out within its useful life.
Re-grind about 20 times. The re-grinding is done by applying a grindstone to the tooth surface, or serration 3.
The helical helical 2 has an involute tooth profile as shown in FIG. 3, and the distance between the helical helical 2 at the tooth base is narrow. By scraping off the grinding wheel to make it thinner, unnecessary interference between the non-grinding surface 6 of the grinding wheel 5 and the helical helix 2 is avoided.

However, since the grinding wheel 5 is used for grinding and is worn out by dressing, in the case of the grinding wheel 5 having a thin tip as described above, the outer diameter of the grinding wheel 5 decreases early, resulting in a shortened service life. Because it is short and therefore the required number of whetstones 5 increases,
There were problems with shaving, such as high processing costs.This idea was made to solve the above problems, and provides a shaving cutter that does not require the tip of the grinding wheel for re-grinding to be particularly thin. The purpose is to In other words, as mentioned above, shaving processing is a processing method in which the shaving cutter and the gear to be cut are meshed together as if they were a set of screw gears, and the two are rotated with a slight pushing force. When using the shaving cutter method, not all of the helical helix in the shaving cutter acts on the workpiece gear, but the part on the tooth tip side that is slightly lowered toward the tooth base from the meshing pitch circle position acts on the workpiece gear. However, the part closer to the root of the tooth does not act on the gear being cut. In addition, since the shaving cutter and the gear to be cut mesh with each other with a slight push-in force, if the thickness of the teeth of the shaving cutter becomes thinner due to re-grinding, the shaving cutter and the gear to be cut will mesh with each other. The distance between the axes of the shaving cutter becomes shorter, and the part of the shaving cutter near the root of the helical tooth also acts on the gear being cut. Therefore, the boundary point between the part that does not act on the gear being cut and the part that does act on the helical part of the shaving cutter moves toward the root side as the tooth thickness and tooth depth become smaller due to re-grinding. do. Therefore, in this design, the root side portion of each tooth that has an involute tooth profile and serrations along the tooth depth direction,
Along the line sequentially connecting the boundary point between the part that acts on the work gear and the part that does not act on the gear at the initial tooth thickness and each boundary point when the tooth thickness is gradually reduced by re-sharpening. The structure has been shaved off in advance,
With this configuration, the spacing between the helical helical parts on the root side becomes wider, so the grinding wheel can be prevented from unnecessarily interfering with the helical helical parts without having to make the grinding wheel particularly thin for re-grinding. It can be done.

An embodiment of this invention will be described below with reference to FIG.

FIG. 5 is a partial sectional view showing the tooth profile of the shaving cutter according to this invention. Serrations 12 are formed along the direction, and a portion of the serrations 12 on the root side is ground down and removed. That is, the portion indicated by the broken line in FIG. 5 is the removed portion 13, and this portion does not act on the gear to be cut during the shaving process and is removed by re-grinding. The removal part 13
To further explain, the symbols a and b in FIG.
is near the boundary between the part of the serration 12 that acts on the gear to be cut and the part that does not act on the gear when the tooth thickness is sufficiently thick in an unused state, and the end b is located when the tooth thickness of the helical helical 11 is again The removal part 1 is the boundary point between the part that acts on the gear to be cut and the part that does not act on the gear that has been reduced to the final thickness by grinding.
3 is a section defined by linearly connecting the starting end a and the ending end b. That is, starting point a
The line connecting the terminal point b and the terminal point b becomes the locus of the boundary point.

Therefore, in the above-mentioned shaving cutter 10, the distance between the helical helices 11 on the root side becomes wider by the amount by which the removed portion 13 is removed, and therefore the tip of the whetstone for re-grinding becomes wider. Even if the part is not particularly thin, there will be no interference between the helix 11 and the grinding wheel, and as a result, the useful life of the grinding wheel can be extended.

In the above embodiment, the shaving cutter with an involute tooth profile was used as an example, but the invention can also be applied to a shaving cutter with other tooth profiles.

As is clear from the above explanation, according to this invention, the root side portion of each tooth that has an involute tooth profile and serrations formed along the tooth depth direction is The tooth root is ground down in advance along the line connecting the boundary points between the part that acts on the tooth and the part that does not act on it, and each boundary point where the tooth thickness has been gradually reduced by re-sharpening. A space large enough to insert the whetstone can be secured between the side hems, and therefore there is no need to make the whetstone particularly thin to avoid unnecessary interference with the hems. , the useful life of the grindstone can be extended, and at the same time, the conventional forming work for thinning the tip of the grindstone can be eliminated, and the cost required for shaving processing can also be reduced.

[Brief explanation of the drawing]

Fig. 1 is a partially omitted front view showing an example of a conventional shaving cutter, Fig. 2 is a schematic diagram for explaining the shaving processing method, Fig. 3 is a detailed sectional view of the part shown in Fig. 1, FIG. 4 is a detailed view showing the re-grinding state, and FIG. 5 is a partial sectional view showing an embodiment of this invention. 10... Shaving cutlet, 11... Hasuba, 12... Serration, 13... Removal part,
a, b... Ends (of the removed part).

Claims (1)

[Scope of Claim for Utility Model Registration] In a shaving cutter having an involute tooth profile in which the tooth surface is a convex arc surface and has serrations formed on the tooth surface along the tooth depth direction, the root side portion of each tooth is The boundary point between the part that does not act on the workpiece gear and the part that does act on the workpiece gear at the initial tooth thickness state, and the part that does not work on the workpiece gear at each tooth thickness state when the tooth thickness is successively reduced by re-sharpening. A shaving cutter characterized by being shaved off along a line sequentially connecting each boundary point with the acting part.