JP4785002B2 - Plunge cut shaving cutter for internal gear - Google Patents

Description

  The present invention mainly relates to a shaving cutter for finishing a tooth surface before heat treatment of an internal gear for power transmission in a passenger car.

Shaving is the best way to finish external gear tooth surfaces at low cost and high efficiency, and it is widely used in the industry. As shown in Fig. 1, the construction method includes a conventional method in which the feed of the shaving cutter (2) repeats relative lateral movement (4) in the direction parallel to the axis of the work gear (1), and shaving. There is a plunge cut method in which the cutter (2) feeds with only infeed (3) (no relative lateral feed), which is the radial movement of the work gear (1). The plunge cut method is widely used. As shown in Patent Document 1, a plunge cut method with high productivity has been established in common sense for the tooth surface finishing of conventional external gears.
Japanese Unexamined Patent Publication No. 04-347838

  However, due to the power transmission mechanism of the gear device, the internal gear is less frequently applied than the external gear, so that the tooth surface finishing method itself has not been so focused. Therefore, the plunge cut method has not been applied to shaving the internal gear, and the conventional method has been the only method for shaving the internal gear. The reason is that the cutter's design and production technology is also natural, and because it is an internal gear, the cutter must be small in size, and the plunge cut method that simultaneously processes the entire tooth width of the internal gear becomes insufficient in rigidity, and it is The important biting property was extremely lowered, and there was no processing cost. However, interest in the accuracy of the internal gear of the planetary gear mechanism has increased as a measure to reduce the inaccurate noise of passenger cars, and the need for shaving finish has increased as in the case of the external gear. Against this background, special machines for machining internal gears or special equipment for producing small-diameter cutters (serration machines, tooth profile grinders) have been developed to meet high efficiency, high accuracy, and low cost. I came.

  On the other hand, although internal gear shaving is slight, it has already been put into practical use 35 to 40 years ago, but all were conventional methods. Since the superiority of the plunge cut method for external gears has been established in modern times, we have tried the plunge cut shaving process for internal gears with that know-how, but the result is that the cutter is difficult to bite and cannot be easily machined. On the other hand, with conventional machining, a cutting amount close to the machine command value can be obtained, and the conventional theory that conventional is known for internal gear shaving has been proved. However, the planetary internal gear (5) for passenger cars has many teeth and a wide width, so conventional machining requires a long machining time of 100 to 180 seconds, which has become a major bottleneck to reject the introduction of the line.

  An object of the present invention is to solve such a problem and provide a plunge cut shaving cutter for an internal gear that can embody a plunge cut method and contribute to productivity improvement as in the case of an external gear.

  For this reason, the present invention increases the serration cutting edge pitch of the cutter cutting edge beyond 2.4 mm and reduces the serration cutting edge width ratio to the serration cutting edge pitch to 0.25 or less so that a large shaving process can be performed with a small indentation load. The above-mentioned problems of the conventional products have been solved by providing a plunge cut shaving cutter for an internal gear characterized in that the amount of the internal gear can be obtained by plunge cut shaving.

  In the present invention, with this configuration, the serration cutting edge pitch of the cutter cutting edge is increased beyond 2.4 mm, and the serration cutting edge width ratio with respect to the serration cutting edge pitch is reduced to 0.25 or less, so that a large shaving with a small indentation load is performed. Since the internal gear can be plunge cut shaved by obtaining a machining amount, the plunge cut shaving cutter for internal gear that can contribute to productivity improvement by embodying the plunge cut method as well as for external gears is provided. To become.

  Preferably, the serration cutting edge pitch is suitably 2.45 to 3.5 mm, and the serration cutting edge width ratio with respect to the serration cutting edge pitch is 0.25 or less. The larger the serration cutting edge pitch, the smaller the contact area. However, if the serration cutting edge pitch exceeds 3.5 mm, another problem will occur that the tooth surface will be poor and should not be applied.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 (a) is a cross-sectional view of the main part showing the feeding method of the shaving cutter (2) with respect to the work gear (1), (b) is a schematic right side view of (a), and FIG. 2 (a) is the work gear. 1 is a cross-sectional view of a main part showing a conventional feeding method of a shaving cutter (2) with respect to (1), and (b) is a plunge cutting method for a work gear (5) of a shaving cutter cutting edge (18) according to an embodiment of the present invention. FIG. 3A is a perspective view of an internal gear (5) that is a work gear according to the embodiment of the present invention, and FIG. 3B is an internal gear machining method according to the embodiment of the present invention. A perspective view of the plunge cut shaving cutter (19), FIG. 4 (a) is a side view showing a method of actually measuring the shaving amount of the internal gear (5), which is the work gear of the embodiment of the present invention, and a Vietween ball diameter ( Between Ball Distance) BBD (28) is measured. (B) is the elements on larger scale of the ball | bowl (22) part of (a). (C) is a perspective view of the serration cutting blade for one tooth of the plunge cut shaving cutter (19) for machining the internal gear in FIG. 3 (b), and (d) is the plunge cut shaving for machining the internal gear in FIG. 3 (b). (E) is an enlarged view of the serration cutting blade for one tooth of (d) (21), and an enlarged view of the tooth tip surface of each tooth row of the cutter (19). (f) is an enlarged cross-sectional view of an essential part showing a combination of tooth profile shapes during plunge cut shaving processing of one serration cutting blade (21) of a shaving cutter with respect to one tooth (24) of an external gear to be cut in FIG. g) is an enlarged cross-sectional view of a main part showing a contact area (14) of one serration cutting edge (21) of a shaving cutter when a cutting amount (23) is provided in one tooth groove (6) of an internal gear to be cut; i) Plunge cutter of the 1 serration cutting blade (21) of the shaving cutter for one tooth groove (6) of the internal gear to be cut. It is an enlarged sectional view showing a combination of a tooth profile during shaving.

  As shown in FIG. 2 (b), the plunge-cut shaving cutter for internal gears according to the embodiment of the present invention has a serration cutting edge pitch (16) larger than 2.4 mm and the serration cutting edge pitch. By reducing the serration cutting edge width ratio (17/16), which is the ratio of the serration cutting edge width (17) to (16), to less than 0.25, a large amount of shaving can be obtained with a small indentation load. The gear can be plunge cut shaved.

The inventor considered the difference between the external gear and the internal gear in terms of the conventional machining of the reason why the internal gear tooth surface (6) (FIG. 3 (a)), which is the work gear, cannot be sufficiently shaved by the plunge cut method. .
First, in the conventional system, the contact range between the tooth width of the shaving cutter and the internal gear as the work gear is 6 to 12 mm (8 mm) around the intersection of both axes as shown in FIG. On the other hand, as shown in FIG. 2 (b), in the plunge cut method, the range of contact between the two teeth is between the full widths of the internal gears (4) by modifying the cutter teeth. Therefore, in the plunge cut method, the surface pressure per tooth width unit length decreases as the gear tooth width increases, and the serration cutting edge (10) becomes difficult to bite into the internal gear tooth surface, resulting in reduced sharpness and workability. .
Secondly, this is common to the external gear, but the cutter for the external gear is not related to the size of the work gear, and has a large diameter compared to the cutter for the internal gear. Even the plunge cut has advantageous conditions in terms of the rigidity of the support system (cutter hole diameter) of the machine.
Here, the shaving cutter sizes for the external gear and the internal gear are compared.
For internal gear For external gear
Cutter outer diameter φ70 to φ120 φ175 to φ325
Cutter hole diameter φ30 ~ φ50 φ63.5 ~ φ100
Third, as shown in FIG. 4 (f), in the external gear machining, the tooth surface shape combinations of the work gear and the shaving cutter are convex (11) and convex (12). As shown in FIG. 4 (g), the internal gear machining is a combination of concave (13) and convex (12). As shown in FIG. 4 (g), the contact length (14) in the tooth profile direction suddenly increases when the bite is applied. extend. This is about the meshing of one cutter crest and one internal gear groove.
Fourthly, compared with meshing with the external gear, meshing with the internal gear increases the meshing normal length, that is, the meshing rate, so that the number of simultaneous contact points also increases. This is a description of the characteristic points related to the entire meshing range.

  From these considerations, in the internal gear plunge cut method, both the plunge cut characteristic and the internal gear machining characteristic have both characteristics that lower the workability. In other words, the contact area must be the largest among the four methods of conventional and plunge cuts for external gears, and conventional and plunge cuts for internal gears. Therefore, in order to discharge chips, a large pressing load must be applied to the internal gear to increase the surface pressure per unit area. As a result, there are decisive reasons for avoiding the construction method, such as reduced machining accuracy, instability, or short cutter life.

The inventor can increase the contact surface pressure between the tooth surfaces with a smaller indentation load at the meshing point of the internal gear (5) and the cutter (19), which are successively rotated, and can be processed in the same manner as the external gear. In order to reduce the contact area between the tooth surfaces of the internal gear and the cutter, it is desirable to reduce the serration cutting edge pitch (16) of the cutter cutting edge as shown in FIG. 2 (b). We have invented a means to increase the width and make the serration cutting edge width (17) thinner than before.
The conventional serration cutting edge pitch is 1.75 to 2.0mm and the cutting edge width is 0.7 to 0.8mm, which is the size of the comb tool used when machining serration cutting edge grooves, even if the tooth width is 20mm, it is 50mm. However, the serration cutting edge pitch setting was almost the same, but from the results of the present invention, the serration cutting edge pitch (16) is 2.45 to 3.5 mm, and the serration cutting edge width (17) with respect to the serration cutting edge pitch (16). It was confirmed that the serration cutting edge width ratio (17/16), which is the ratio, is 0.25 or less. The larger the cutting edge pitch, the smaller the contact area. However, if the cutting edge pitch exceeds 3.5 mm, another problem will occur that the tooth surface will not be finished.

As shown in Table 1, the main internal gear specifications of the internal gear to be cut are module: 2.1, pressure angle: 20 °, number of teeth: 58, helix angle: 20 ° RH, width: 30mm. With the original number of teeth: 43, helix angle: 12 ° RH, tooth width: 36mm, G is the front meshing rate, W is the total load for pushing the shaving cutter, and plunge cut shaving is applied to the conventional product and the invention. 4 (a) is a side view showing a method for measuring the amount of shaving of the internal gear (6), which is the work gear shown in FIG. 4 (a). Measured as 20).
As shown in Table 1, in Example 1, the product of the present invention increases the serration cutting edge pitch of the cutter cutting blade to 2.45 mm, exceeding the 2.0 mm of the conventional product, and the serration cutting blade width of the conventional product. In contrast to 0.7 mm and the serration cutting edge width ratio (t / P) = 0.35, the present invention has a serration cutting edge width of 0.5 mm and a serration cutting edge width ratio (t / P) = 0.20. As a result, in the product of the present invention, the total load for pushing the shaving cutter per unit length of contact length is increased to about twice that of the conventional product, and as a result, the change in the measured value of the bitein ball diameter BBD (28) before and after processing (20 ), The actual machining amount of shaving (20) was increased from 0.02 to 0.1 mm of the conventional product, and the tooth surface machining allowance (25) comparable to the external gear could be obtained.

  The plunge cut shaving cutter for internal gears according to the embodiment of the present invention has such a configuration that the serration cutting blade pitch of the cutter cutting blade is increased beyond 2.4 mm, and the serration cutting blade width ratio with respect to the serration cutting blade pitch is increased. The internal gear can be plunge cut shaved by reducing it to less than 0.25 and obtaining a large amount of shaving with a small indentation load. Providing a plunge cut shaving cutter for internal gears that can contribute to productivity improvement by embodying the plunge cut method as well as for external gears. It became.

  Preferably, the serration cutting edge pitch is 2.45 to 3.5 mm and the serration cutting edge width ratio with respect to the serration cutting edge pitch is 0.25 or less. The larger the serration cutting edge pitch, the smaller the contact area. However, if the serration cutting edge pitch exceeds 3.5 mm, another problem will occur that the tooth surface will be poor and should not be applied.

(A) is principal part sectional drawing which shows the feeding method of the shaving cutter (2) with respect to a to-be-cut gear (1), (b) is a schematic right view of (a). (A) is principal part sectional drawing which shows the feeding method of the conventional system of the shaving cutter (2) with respect to a work gear (1), (b) is the work gear of the shaving cutter cutting blade (18) of embodiment of this invention. Sectional drawing which shows the principal method which shows the feed method of the plunge cut system with respect to (5). (A) is a perspective view of an internal gear (5) that is a work gear according to an embodiment of the present invention, and (b) is a perspective view of a plunge cut shaving cutter (19) for machining an internal gear according to an embodiment of the present invention. (A) is a side view which shows the actual measurement method of the amount of shaving of the internal gear (5) which is a to-be-cut gear of embodiment of this invention, and measures a Between ball diameter (Between Ball Distance) BBD (28). (B) is the elements on larger scale of the ball | bowl (22) part of (a). (C) is a perspective view of the serration cutting blade for one tooth of the plunge cut shaving cutter (19) for machining the internal gear in FIG. 3 (b), and (d) is the plunge cut shaving for machining the internal gear in FIG. 3 (b). (E) is an enlarged view of the serration cutting blade for one tooth of (d) (21), and an enlarged view of the tooth tip surface of each tooth row of the cutter (19). (f) is an enlarged cross-sectional view of an essential part showing a combination of tooth profile shapes during plunge cut shaving processing of one serration cutting blade (21) of a shaving cutter with respect to one tooth (24) of an external gear to be cut in FIG. g) is an enlarged cross-sectional view of a main part showing a contact area (14) of one serration cutting edge (21) of a shaving cutter when a cutting amount (23) is provided in one tooth groove (6) of an internal gear to be cut; i) Plunge cutter of the 1 serration cutting blade (21) of the shaving cutter for one tooth groove (6) of the internal gear to be cut. It is an enlarged sectional view showing a combination of a tooth profile during shaving.

Explanation of symbols

5: Internal gear to be cut, 6: 1 tooth groove of internal gear to be cut, 16: Serration cutting edge pitch
17: Serration cutting blade width, 19: Shaving cutter, 21: Serration cutting blade G: Front meshing rate, W: Shaving cutter indentation load BBD: Between Ball Distance

Claims (2)

  Increase the serration cutting edge pitch of the shaving cutter cutting edge beyond 2.4mm and reduce the serration cutting edge width ratio to the serration cutting edge pitch to 0.25 or less to obtain a large amount of shaving with a small indentation load. A plunge cut shaving cutter for an internal gear, wherein the internal gear can be plunge cut shaved.   2. The plunge cut shaving cutter for an internal gear according to claim 1, wherein the serration cutting edge pitch is 2.45 mm to 3.5 mm, and the serration cutting edge width ratio with respect to the serration cutting edge pitch is 0.25 or less.

Images