JP2018001340A - Method of manufacturing gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To impart a non-continuous pitch error to an outer tooth gear without the necessity for changing a notch amount in the middle of processing by a method suitable for mass production.SOLUTION: A method of manufacturing a gear comprises: a preparation process for preparing a dresser (for example, a dress gear 7) to which a non-continuous pitch error is imparted so as to correspond to an outer tooth gear (step ST1); a grindstone forming process for forming an inner tooth grindstone 6 by using the dresser (step ST2); and a honing process for applying honing to a ground gear (workpiece W) by using the inner tooth grindstone 6 (step ST3). A tooth number of the dresser and that of the ground gear are made to be the same, and a tooth number of the inner tooth grindstone 6 is set at an integral multiple of the tooth numbers.SELECTED DRAWING: Figure 5

Description

  The present invention relates to the manufacture of external gears used in, for example, vehicle drive systems, and more particularly to a manufacturing method in which pitch errors are intentionally discontinuous in order to reduce noise.

  Conventionally, many external gears have been used in transmissions and differentials in vehicle drive systems. However, due to errors in the tooth surface accuracy and insufficient rigidity of the gear support system and teeth themselves, There has been a problem that meshing fluctuations occur in a predetermined cycle based on the number of teeth, thereby increasing noise.

  On the other hand, conventionally, it has been proposed to reduce the noise by reducing the periodicity of the meshing variation as described above by intentionally discontinuating the gear pitch error. As an example, in Patent Document 1, for example, in the finishing of a gear using a disc grindstone, when the tooth is sharpened by indexing one tooth, the depth of cut is once for each number of teeth that are mutually prime with the number of teeth of the gear to be cut. Or a method of feeding gears by the number of teeth that are prime to each other is disclosed.

JP-A-7-35218

  However, as in the conventional example (Patent Document 1), finishing a gear by indexing one tooth is extremely inferior in productivity and incurs an increase in cost, so it must be said that it is not suitable for mass production. I don't get it. In addition, as finishing processing suitable for mass production, it is generally considered that honing is performed with an internal tooth grind after grinding with a threaded grindstone. Since it meshes with a plurality of teeth of the work gear, a technique such as indexing one tooth in the conventional example cannot be applied.

  In view of such circumstances, the object of the present invention is to be able to give a discontinuous pitch error to the external gear without changing the cutting amount during the machining in a method suitable for mass production. There is to do.

  In order to achieve the above object, in the present invention, by using a dresser having a discontinuous pitch error, an internal grindstone having an integral multiple of the number of teeth is formed, and honing is performed using the internal grindstone. The same pitch error as that of the dresser is transferred to the work gear.

  That is, the present invention is a gear manufacturing method in which a discontinuous pitch error is given to an external gear, and the discontinuous pitch error is given to correspond to the external gear. A step of preparing a dresser, a step of forming an internal grindstone with the dresser, and a step of honing a work gear with the internal grindstone, and the same number of teeth of the dresser and the work gear. The number of teeth of the internal grindstone is an integral multiple of the number of teeth of the dresser and the work gear.

  By the above-described method, first, a discontinuous pitch error is given to the dresser by, for example, indexing one tooth as in the conventional example. If an internal grindstone having an integral multiple of the number of teeth is formed using this dresser, an integral multiple of the discontinuous pitch error of the dresser is transferred to the internal grindstone. This is because if the number of teeth of the internal grindstone is an integral multiple of the dresser, the teeth of the internal grindstone that meshes with any tooth of the dresser will always be the same no matter how many rotations.

  When the work gear is honed using the internal grindstone in which the discontinuous pitch error is transferred by integer multiplication, the pitch error is transferred to the work gear this time. That is, since the number of teeth of the internal grinding wheel is an integral multiple of the work gear, the tooth of the internal grinding wheel that meshes with any tooth of the work gear is always the same no matter how many times it rotates. Therefore, the dresser pitch error can be directly transferred to the work gear.

  In this way, it is not a method inferior in productivity such as indexing one tooth in the conventional example (Patent Document 1), and by honing processing suitable for mass production, it is not necessary to change the cutting amount during processing, A discontinuous pitch error can be given to the work gear. That is, the pitch error of the external gear can be intentionally discontinuous without deteriorating productivity and increasing costs due to this.

  In order to give a discontinuous pitch error to the dresser, when the dresser is sharpened by indexing one tooth as described above, a discontinuous pitch error is given by changing the cutting amount. Thereafter, superabrasive grains such as diamond are preferably fixed by electrodeposition or the like in order to improve the wear resistance of the tooth surface.

  As described above, according to the gear manufacturing method according to the present invention, an internal grindstone having an integral multiple of the number of teeth is formed using a dresser having a discontinuous pitch error. Since the honing of the work gear is performed, it is possible to intentionally give a discontinuous pitch error to the external gear without incurring productivity deterioration and cost increase. As a result, the periodicity of the meshing variation is alleviated and noise is reduced.

It is a figure which shows schematic structure of the gear honing machine which concerns on embodiment of this invention. It is a perspective view explaining a mode that the external teeth of the work set on the gear honing machine mesh with the internal teeth of the internal grinding wheel and rotate. It is a perspective view explaining a mode that a base metal of a dress gear is sharpened with a rotary dresser. It is explanatory drawing which shows that the number of teeth of an internal gear is an integral multiple of the number of teeth of a dress gear (number of teeth of a workpiece). It is a flowchart which shows the flow of the manufacturing method of embodiment.

  Hereinafter, an embodiment in which the present invention is applied to manufacture of an external gear used in a drive system of a vehicle will be described. This external gear is intentionally provided with a discontinuous pitch error in order to reduce noise. That is, in general, a gear has a meshing variation with the number of teeth as a basic cycle, and noise may increase. In this embodiment, the meshing variation is reduced by making the pitch error discontinuous. Periodicity is eased to reduce noise.

  FIG. 1 shows a schematic configuration of a gear honing machine 1 that performs finish processing (gear honing) of an external gear according to the present embodiment. A workpiece W that is a work gear on which external teeth w1 are formed is attached to It is attached to the gear honing machine 1 via the shaft 2. The mounting shaft 2 is rotatably supported between both centers of the head stock 3 and the tail stock 4 and is parallel to the axis X of the mounting shaft 2 by the work table 5 integrally with the head stock 3 and the tail stock 4. It is reciprocated in the table axis direction (left-right direction in the figure).

  Further, the gear honing machine 1 is provided with a ring-shaped internal grinding wheel 6 so as to be able to mesh with the workpiece W. Although not shown, the gear honing machine 1 is rotatably supported by the grinding wheel head of the gear honing machine 1. Yes. That is, as shown schematically in FIG. 2, the rotation axis Y of the internal grindstone 6 forms an intersecting angle θ with the axis X of the mounting shaft 2, via a belt (not shown). Thus, the internal grindstone 6 is rotated.

  Then, the external teeth w1 of the workpiece W set on the gear honing machine 1 via the mounting shaft 2 as described above are engaged with the internal teeth 6a of the internal grinding wheel 6 and rotated, and the meshed portion is ground. While supplying the liquid, the work table 5 is reciprocated in the table axis direction. At this time, since the rotation axis Y of the internal grinding wheel 6 forms an axis X of the mounting shaft 2, that is, the rotation axis of the workpiece W, the tooth surfaces that mesh with each other are polished while sliding obliquely. Become.

-Honing of workpieces-
In addition to attaching the workpiece W as described above, a dress gear 7 (see FIG. 3) or a dress ring can be attached to the attachment shaft 2 of the gear honing machine 1. Although not shown, the dressing is cylindrical and is a dresser for forming the inner diameter surface (tooth tip surface) of the internal grindstone 6. The dress gear 7 is a dresser whose outer teeth 7a are set to the same gear specifications as the outer teeth w1 of the workpiece W, and is used for molding the tooth surfaces of the inner teeth 6a of the inner grindstone 6.

  That is, the internal grinding wheel 6 is worn by repeating the honing process of the workpiece W described above. For example, each time the workpiece W is machined a predetermined number of times, the on-machine molding of the internal grinding wheel 6 by the dress gear 7 and the dressing ring is performed. I do. Specifically, first, the dressing ring is attached to the mounting shaft 2 instead of the workpiece W, and the inner surface (tooth surface) of the internal grinding wheel 6 is brought into contact with the outer peripheral surface thereof, and the gear honing machine 1 is operated. Thus, the inner diameter surface of the internal gear 6 is formed.

  Next, instead of the dress ring, the dress gear 7 is attached to the attachment shaft 2 and the gear honing machine 1 is operated. That is, the external teeth 7a of the dress gear 7 (see FIG. 3) are engaged with the internal teeth 6a of the internal grindstone 6 and rotated, and the work table 5 is reciprocated to form the tooth surfaces. Then, instead of the dress gear 7, the work W is attached to the attachment shaft 2, and the internal teeth 6 a of the internal grinding wheel 6 are engaged with the external teeth w 1 to operate the gear honing machine 1 as described above.

  In this way, after the honing process is performed on the tooth surfaces of the predetermined number of workpieces W, the internal grindstone 6 is formed again using the dressing ring and the dress gear 7 as described above, and this is repeated. The dress gear 7 for forming the tooth surface of the internal grinding wheel 6 in this way is designed to have the same shape as the external gear after the work W is honed, and in this embodiment, intentionally discontinuous pitch errors are given. Has been.

−Transcription of dress gear pitch error−
That is, as a first feature of the present embodiment, the dressing gear 7 is configured such that, as shown in FIG. When sharpening, the position of the rotary dresser 8 is adjusted, and the pitch error is given by changing the cut amount. Then, by attaching superabrasive grains such as diamond and CBN to the tooth surfaces of the external teeth 7a by electrodeposition or the like, the dress gear 7 has sufficient wear resistance.

  As a second feature, as shown in FIG. 4, the number of teeth of the internal grindstone 6 to which honing is performed by the dress gear 7 is set to the number of teeth of the dress gear 7, that is, the number of teeth of the external gear as a product. It is set to an integer multiple of. That is, in the example shown in FIG. 4, the number of teeth of the dress gear 7 is 30, and the number of teeth of the internal grindstone 6 that meshes with this is set to three times (90). For this reason, for example, the internal teeth 6a (indicated by ☆) of the internal grindstone 6 that mesh with the external teeth 7a indicated by the ★ marks of the dress gear 7 are always the same no matter how many times the dress gear 7 and the internal grindstone 6 rotate. It becomes.

  Thus, when the internal gear 6 is formed using the dress gear 7, the discontinuous pitch error of the dress gear 7 is multiplied by an integer and transferred to the internal gear 6. Then, when the workpiece W is honed using the internal grindstone 6 as described above with reference to FIGS. 1 and 2, the pitch error of the dress gear 7 is transferred to the workpiece W as it is. This is because, as in the relationship between the internal grindstone 6 and the dress gear 7, the teeth of the internal grindstone 6 that meshes with any tooth of the workpiece W are always the same.

  The flow of the manufacturing method described above is shown in the flowchart of FIG. 5, as described above with reference to FIG. 3, a preparation process (steps) for preparing dressing gear 7 (dresser) to which dressing and discontinuous pitch error are imparted. ST1), as described above with reference to FIG. 4, a grindstone forming step (step ST2) for forming the internal gear 6 with the dress gear 7, and the internal grindstone 6 as described above with reference to FIGS. Is attached to the gear honing machine 1, and a honing process (step ST3) for performing honing of the workpiece W is provided.

  The honing process includes a first determination step (step ST4) for determining whether or not the number of honing operations has reached a predetermined number or more that requires correction of the tooth profile of the internal grindstone 6. Here, a negative determination (NO) is made. If, on the other hand, the process returns to the honing process and an affirmative determination is made (YES), the process proceeds to a second determination process (step ST5) in which it is determined whether or not a limit number corresponding to the wear limit of the internal grinding wheel 6 has been reached. If a negative determination (NO) is made here, the process returns to the grindstone forming step. On the other hand, if an affirmative determination (YES) is also made here, the manufacturing method is terminated.

  As described above, according to the gear manufacturing method according to the present embodiment, the number of teeth of the dress gear 7 for forming the internal grinding wheel 6 is made the same as the number of teeth of the workpiece W, while the internal grinding wheel 6 Since the number of teeth is an integral multiple of the number of teeth of the dress gear 7 and the workpiece W, the pitch error previously applied to the dress gear 7 can be transferred to the workpiece W by honing the workpiece W with the internal grinding wheel 6. .

  This is not a method of indexing one tooth that is inferior in productivity, but by a honing process suitable for mass production, a pitch that is intentionally discontinuous in the workpiece W without the need to change the cutting amount during the process. An error can be added. Therefore, the periodicity of the meshing variation of the external gear can be relaxed without deteriorating the productivity and the increase in cost due to this, thereby reducing the noise.

-Other embodiments-
The configuration of the present invention is not limited to the above-described embodiment, but includes other various forms. That is, although the manufacturing method of the said embodiment uses the helical gear (helical gear) as an external gear, it is not limited to this, For example, a spur gear and a bevel gear may be sufficient.

  Further, as shown in the flowchart of FIG. 5, the manufacturing method of the embodiment includes a grindstone forming step (step ST <b> 2) for forming the internal grindstone 6 using the prepared dress gear 7. Before, you may make it rough-process on the internal-grinding stone 6 using another dresser with a coarser mesh. In this case, a pitch error may be given to another dresser as well as the dress gear 7, but it is not necessary to give a pitch error.

  Furthermore, as exemplified in the above embodiment, the present invention is not limited to the manufacture of external gears used in vehicle drive systems, and the present invention is also applied to the manufacture of external gears used for various other purposes. can do.

  Since the present invention can reduce noise by the external gear having a discontinuous pitch error without deteriorating productivity and increasing costs, it is highly effective when applied to a vehicle drive system or the like. .

1 Gear honing machine 6 Internal grinding wheel 7 Dress gear (dresser with discontinuous pitch error)
W Workpiece (Machining gear, External gear)

Claims (1)

A gear manufacturing method for imparting a discontinuous pitch error to an external gear,
Preparing a dresser with a discontinuous pitch error so as to correspond to the external gear;
Forming an internal grindstone with the dresser;
Honing a work gear with the internal gear whetstone,
The gear manufacturing method, wherein the number of teeth of the dresser and the work gear is the same, and the number of teeth of the internal grinding wheel is an integral multiple of the number of teeth of the dresser and the work gear.

Images