JP2023055021A - Gear processing method - Google Patents

Abstract

To provide a gear processing method capable of improving processing accuracy of a tooth surface by reducing an interference amount of a tooth root when the tooth surface is cut in post-processing.SOLUTION: Provided is a gear processing method of processing a gear by cutting. The method includes slightly cutting a center of a tooth form 104 so as to satisfy a minimum value of tolerance of OBD or BBD, and after cutting the center of the tooth form 104, cutting tooth surfaces 108, 110 so as to achieve a median value of the tolerance of OBD or BBD.SELECTED DRAWING: Figure 1

Description

The present invention relates to a gear machining method for machining gears by cutting.

Skiving, shaving, hobbing, and shaper processing are known as processing methods for cutting gears.

In skiving, the rotation of the workpiece is synchronized with the rotation of the skiving cutter, which is a cutting tool. It is done in a tilted position. When machining a general spur gear by skiving, gear cutting is performed by moving the skiving cutter parallel to the tooth width direction of the workpiece while keeping the crossed axis angle between the cutter axis and the workpiece axis constant. will be As a result, in skiving, a difference occurs between the rotation direction of the work and the rotation direction of the skiving cutter, and "slip" occurs when the skiving cutter interferes with the work. Using this sliding, the interfering portion is scraped off from the workpiece, and the tooth groove (tooth profile) is machined on the workpiece.

In the shaving process, for example, a shaving cutter, which is a cutting tool, is pressed against and cuts into a rotating work while reciprocating vertically, for example, to machine a tooth profile or the like in the work.

In the gear machining method of Patent Document 1, gear cutting is performed while a skiving cutter is moved not only in the face width direction of the workpiece but also in the circumferential direction, thereby forming a bias tooth profile in which the tip position changes in the face width direction. can be processed.

Japanese Patent Application Laid-Open No. 2020-19096

A gear may be further cut after the shape of the gear is once created, such as finish machining or finish machining after heat treatment. In the following description, this is called "post-processing". The post-processing can be performed by skiving as shown in Patent Document 1, or by shaving, hobbing, or shaping.

However, when the cutter blade is cutting the tooth flank (side of the tooth), when the cutter blade is processing near the tooth root, the cutting load abruptly increases due to the variation in meshing, causing the workpiece and cutter to vibrate and rotate. Uneven speed may occur. As a result, the shape of the tooth flank is also disturbed, resulting in a problem of poor machining accuracy.

In view of such problems, the present invention provides a gear machining method capable of improving machining precision of the tooth flank by reducing the interference amount of the tooth root when the tooth flank is cut in post-machining. It is an object.

In order to solve the above problems, a representative configuration of the gear machining method according to the present invention is a gear machining method for machining a gear by cutting, wherein the center of the tooth profile is OBD (Over Ball Diameter) or After cutting shallowly to meet the minimum tolerance of BBD (Between Ball Diameter) and cutting the length of the required tooth profile, without changing the depth of cut, the tolerance of OBD or BBD It is characterized by cutting the tooth flank so as to obtain the median value.

"Shallow to meet the minimum tolerance" means aiming for the upper limit of OBD for external gears and aiming for the lower limit of BBD for internal gears. The OBD or BBD then tends toward the median value because the tooth spaces are widened by cutting the tooth flanks. At this time, since the depth of cut is not changed, it is possible to reduce the amount of interference near the root of the tooth without cutting more than the necessary length of the tooth profile, and it is difficult for meshing fluctuation to occur. Therefore, it is possible to improve the machining precision of the tooth flanks without fluctuations in the cutting resistance.

The above gear cutting may be performed by skiving, shaving, hobbing, or shaping. Machining accuracy can be improved in the post-machining of the tooth flank by these machining.

Advantageous Effects of Invention According to the present invention, it is possible to provide a gear machining method capable of improving machining precision of tooth flanks by reducing the amount of interference at the root of the tooth when the tooth flanks are cut in post-machining.

It is a figure explaining the gear machining method in embodiment of this invention. 2 is a flowchart for explaining the gear machining method of FIG. 1; It is a schematic diagram explaining a cutting range.

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in these embodiments are merely examples for facilitating understanding of the invention, and do not limit the invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are given the same reference numerals to omit redundant description, and elements that are not directly related to the present invention are omitted from the drawings. do.

FIG. 1 is a diagram explaining a gear machining method according to an embodiment of the present invention. FIG. 2 is a flow chart for explaining the gear machining method of FIG.

The gear machining method is a method of machining gears by cutting. applied to "processing". Post-processing can be performed by so-called skiving, shaving, hobbing or shaping. Post-processing by skiving will be described below.

In the gear machining method, first, a workpiece 100 having a gear shape (tooth profile) created by pre-machining is prepared, and the rotation phases of the workpiece 100 and the skiving cutter 102 shown in FIG. Start post-processing.

Specifically, as shown in FIG. 1( a ), the required tooth profile length of the tooth profile 104 of the work 100 is shallow so as to satisfy the minimum allowable error of OBD (Over Ball Diameter). If so, cutting is performed aiming at the upper limit (step S100). Here, in step S100, the center A of the tooth profile 104 indicated by the chain line in the drawing is aligned with the center B of the skiving cutter 102 also indicated by the chain line, thereby cutting the center of the tooth profile. In the case of the external gear, the upper limit of the OBD is aimed, but in the case of the internal gear, the lower limit of the BBD is aimed.

Next, the phase of the skiving cutter 102 is changed to the left with respect to the work 100 as shown in FIG. 1(b). As a result, the center B of the skiving cutter 102 is positioned to the left of the center A of the tooth profile 104, and only the left tooth flank 108 of the tooth profile 104 is cut (step S102).

Subsequently, the phase of the skiving cutter 102 is changed to the right side with respect to the workpiece 100 as shown in FIG. 1(c). As a result, the center B of the skiving cutter 102 is positioned on the right side of the center A of the tooth profile 104, and only the right tooth flank 110 of the tooth profile 104 is cut (step S104).

When the left and right tooth flanks 108 and 110 are cut, the tooth space is widened, so the OBD becomes smaller (in the case of an internal gear, the BBD becomes larger). As shown in FIGS. 1(a), (b), and (c), the depth of cut (the depth of the skiving cutter 102) is not changed, but when the left and right tooth flanks 108 and 110 are cut, the OBD becomes smaller. To go. The cutting of the left and right tooth flanks 108 and 110 is performed so as to be the median value of the allowable error of the OBD or BBD.

FIG. 3 is a schematic diagram for explaining the cutting range. Note that the shapes and dimensional ratios in FIG. 3 are greatly exaggerated for convenience of explanation. The shape indicated by the dashed line P represents the prior art, and shows an example in which the center of the tooth profile 104 is cut to the median allowable error of the OBD or BBD. That is, the dashed line P cuts the left tooth flank 108 and the right tooth flank 110 at the same time.

On the other hand, in the present invention, first, the necessary tooth profile length of the tooth profile 104 is cut as indicated by the dashed line N1. Then, without changing the depth of cut (without changing the depth) and changing the phase, the left tooth flank 108 is cut as indicated by the dashed line N2, and the right tooth flank 110 is similarly cut as indicated by the dashed line N3. (Left and right are in no particular order). Then, in order to generate the same left tooth flank 108 and right tooth flank 110, it can be seen that the dashed lines N1 to N3 of the present invention are farther from the root 106 (cut shallower) than the dashed line P of the prior art. .

According to the gear machining method described above, when cutting the left tooth flank 108 and the right tooth flank 110, since the depth of cut is not changed from when cutting the center of the tooth profile, the amount of interference at the root can be reduced. It is possible to improve the machining accuracy of the tooth flanks because it is difficult for meshing fluctuation to occur. In addition, machining accuracy can be improved in post-machining of the tooth flank by skiving.

In the gear machining method described above, the right tooth flank 110 is cut after the left tooth flank 108 is cut. can be Alternatively, only one of the left tooth flank 108 and the right tooth flank 110 may be cut.

In the gear machining method described above, the allowable error of OBD (Over Ball Diameter) is applied in each of the above cutting processes, but the present invention is not limited to this. In other words, if the gear that has been created by pre-machining is an internal gear, the tolerance of BBD (Between Ball Diameter) is applied to perform each cutting process, so that the tooth flank is formed by skiving. Work accuracy can be improved in post-machining. In the case of OBD of the external gear, the vicinity of the upper limit is aimed, but in the case of BBD of the internal gear, the vicinity of the lower limit is aimed.

Furthermore, in the gear machining method described above, post-machining is performed by skiving, but the present invention is not limited to this, and can be performed by shaving, hobbing, or shaping. In this case, in place of the skiving cutter 102, a shaving cutter is pressed against the rotating workpiece 100 to perform the above-described cutting processes, thereby improving machining accuracy in post-machining of the tooth surface by shaving. can be made

Although the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such examples. It is obvious that a person skilled in the art can conceive of various modifications or modifications within the scope described in the claims, and these also belong to the technical scope of the present invention. Understood.

INDUSTRIAL APPLICABILITY The present invention can be used as a gear machining method for machining gears by cutting.

DESCRIPTION OF SYMBOLS 100... Work, 102... Skiving cutter, 104... Tooth profile, 106... Tooth bottom, 108... Left tooth surface, 110... Right tooth surface

Claims (2)

A gear machining method for machining gears by cutting,
Cut the center of the tooth profile shallow to meet the minimum OBD or BBD tolerance,
A gear machining method, comprising: after cutting the center of the tooth profile, cutting the tooth flank so as to achieve the median allowable error of OBD or BBD without changing the depth of cut. 2. The gear machining method according to claim 1, wherein the gear cutting is performed by skiving, shaving, hobbing, or shaper machining.

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