Gear machining apparatus and gear machining method

Abstract

The heat generated during machining of the gear teeth can be maintained, allowing the gear to be sufficiently plastically deformed. [Solution] The gear machining apparatus machines the tooth surface of the gear to be machined by rotating the gear to be machined while meshing with the machining gear. Each tooth of the machining gear has a projection formed at the same position on its tooth surface that contacts the tooth surface of the gear to be machined.

Description

Technical Field

[0001] The present disclosure relates to a gear processing apparatus that performs processing using gears, and a gear processing method.

Background Art

[0002] There is known a gear processing apparatus that processes the tooth surface of a work gear by rotating the work gear in a meshed state with a processing gear, and causing the tooth surface of the processing gear to contact the tooth surface of the work gear by the protrusions on the tooth surface of the processing gear (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above gear processing apparatus, depending on the arrangement of the protrusions on the tooth surface of the processing gear, the contact of the protrusions with the work gear may become intermittent. For this reason, the heat generation during the processing of the tooth surface of the work gear may not be maintained, and there is a risk that the work gear cannot be sufficiently plastically deformed.

[0005] The present disclosure has been made in view of such problems, and a main object thereof is to provide a gear processing apparatus and a gear processing method capable of maintaining the heat generation during the processing of the tooth surface of a work gear and sufficiently plastically deforming the work gear.

Means for Solving the Problems

[0006] One aspect of the present invention for achieving the above object is a gear processing apparatus that processes the tooth surface of a work gear by rotating the work gear in a meshed state with a processing gear, wherein protrusion portions that contact the tooth surface of the work gear are respectively formed at the same positions on the tooth surfaces of each tooth of the processing gear. Gear machining equipment That is the case. On this flight, The projection may be formed on the entire surface of each tooth of the gear used for machining. On this flight, The aforementioned projection may have a spherical shape. On this flight, The contact angle between the direction of travel of the projection when the machining gear rotates and the tangent line at the position on the spherical surface of the projection where it contacts the tooth surface of the gear being machined may be 45° or less. One aspect of the present invention for achieving the above objective is: A gear machining method in which the tooth surface of a workpiece gear is machined by rotating the workpiece gear while meshed with a machining gear, wherein projections are formed at the same position on the tooth surface of each tooth of the machining gear, and the projections contact the tooth surface of the workpiece gear. When the workpiece gear and the machining gear rotate, the projections on the tooth surfaces of each tooth of the machining gear continuously contact the same portion of the tooth surface of the workpiece gear. Gear machining method That is the case. [Effects of the Invention]

[0007] According to this disclosure, it is possible to provide a gear machining apparatus and a gear machining method that can maintain the heat generated during machining of the tooth surface of a workpiece gear and can sufficiently plastically deform the workpiece gear. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows a schematic configuration of the gear processing apparatus according to this embodiment. [Figure 2] This figure shows an example of a state in which protrusions are formed on the tooth surface of a gear used for machining. [Figure 3] These are top view and side view views of the protrusion. [Figure 4] This is a diagram showing the protruding parts. [Modes for carrying out the invention]

[0009] This embodiment will now be described with reference to the drawings. Figure 1 is a diagram showing the schematic configuration of the gear machining apparatus according to this embodiment. As shown in Figure 1, the gear machining apparatus 1 according to this embodiment machines the tooth surface 22 of the gear to be machined 2 by applying a driving force to the shaft of the machining gear 3 using a power source (not shown) and rotating it while each tooth 21 of the gear to be machined 2 is meshed with each tooth 31 of the machining gear 3. The tooth surface (meshing sliding surface) 22 includes not only the side surface of the tooth, but also the tooth crown and tooth root.

[0010] In this way, the gear machining apparatus 1 meshes the machining gear 3 with the workpiece gear 2 and rotates it, thereby applying stress to the tooth surface 22 of the workpiece gear 2 by the machining gear 3, causing plastic deformation of its surface. This makes it possible to refine the surface structure of the tooth surface 22 of the workpiece gear 2, increase its hardness, and generate the desired compressive stress.

[0011] The workpiece gear 2 is a spur gear used in power transmission systems for automobiles, but is not limited to this; for example, it may be a bevel gear, helical gear, serrated gear, internal gear, rack and pinion, etc. On the other hand, the machining gear 3 is a gear that can mesh with the workpiece gear 2, and it is preferable that the hardness of its tooth surface 32 is higher than the hardness of the tooth surface 22 of the workpiece gear 2.

[0012] Figure 2 shows an example of a state in which protrusions are formed on the tooth surface of a machining gear. As shown in Figure 2, multiple protrusions 33 are formed on the tooth surface 32 of each tooth 31 of the machining gear 3, which abut against the tooth surface 22 of each tooth 21 of the workpiece gear 2.

[0013] Figure 3 shows a top view and a side view of the projection. The projection 33 is formed to protrude perpendicularly from the tooth surface 32 in a substantially hemispherical shape. The projection 33 is formed integrally with the tooth surface 32, but it may also be formed separately from the tooth surface 32.

[0014] Each protrusion 33 of the processing gear 3 makes point contact by abutting against the tooth surface 22 of the workpiece gear 2 when the processing gear 3 and the workpiece gear 2 are engaged. At this time, as shown in FIG. 3, the tip 331 of the protrusion 33 is buried in the tooth surface 22 of the workpiece gear 2. Thereby, the bending stress applied to the tooth root of the workpiece gear 2 is reduced to prevent tooth breakage, and the plastic deformation of the surface layer of the workpiece gear 2 can be caused by generating local high stress.

[0015] FIG. 2(a) is a view of the tooth surface 32a of the tooth 31a in FIG. 1 as seen from above. FIG. 2(b) is a view of the tooth surface 32b of the tooth 31b in FIG. 1 as seen from above. As shown in FIGS. 2(a) and 2(b), protrusions 33a and 33b are formed at the same positions on the tooth surface 32a of the tooth 31a of the processing gear 3 and the tooth surface 32b of the tooth 31b of the processing gear 3, respectively.

[0016] Similarly, protrusions 33 are formed at the same positions on the tooth surfaces 32 of other teeth 31 of the processing gear 3. That is, protrusions 33 are respectively formed at the same positions on the tooth surfaces 32 of each tooth 31 of the processing gear 3. Thereby, every time the workpiece gear 2 rotates once, the protrusions 33 on the tooth surface 32 of the tooth 31 of the processing gear 3 can be continuously abutted against the same portion of the tooth surface 22 of the workpiece gear 2.

[0017] Subsequently, the gear processing method according to the present embodiment will be described using a specific example. For example, as shown in FIG. 1, after the protrusion 33a (FIG. 2(a)) of the tooth 31a of the processing gear 3 abuts against the portion c of the tooth surface 22 of the workpiece gear 2, the workpiece gear 2 further rotates once. Then, this time, the protrusion 33b (FIG. 2(b)) of the tooth 31b abuts against the same portion c of the tooth surface 22 of the workpiece gear 2.

[0018] Furthermore, when the workpiece gear 2 rotates once, the protrusion 33 on the tooth surface 32 of another tooth 31 of the processing gear 3 abuts against the same portion c of the tooth surface 22 of the workpiece gear 2. Thus, every time the workpiece gear 2 rotates once, the protrusion 33 on the tooth surface 32 of the tooth 31 of the processing gear 3 continuously abuts against the same portion c of the tooth surface 22 of the workpiece gear 2.

[0019] As described above, an example has been explained in which the projections 33 on the tooth surface 32 of the teeth 31 of the machining gear 3 abut against the same portion c of the tooth surface 22 of the workpiece gear 2, but the invention is not limited to this example. The other projections 33 of each tooth 31 of the machining gear 3 are also positioned on each tooth surface 22 such that they continuously abut against other identical portions of the tooth surface 22 of the workpiece gear 2 each time the workpiece gear 2 rotates.

[0020] In this way, each projection 33 of the machining gear 3 continuously contacts the same portion of the workpiece gear 2. This continuous contact of the projections 33 maintains the heat generated during machining, allowing the tooth surface 22 of the workpiece gear 2 to be sufficiently plastically deformed.

[0021] Furthermore, as described above, each projection 33 of the machining gear 3 may be formed densely and uniformly across the entire surface of the tooth surface 32 of each tooth 31 of the machining gear 3 so as to continuously contact the same portion of the workpiece gear 2.

[0022] For example, it is preferable that the tooth surface 32 of the machining gear 3 is densely and uniformly formed so that the entire tooth surface 22 of the workpiece gear 2 is machined uniformly during one rotation. This eliminates the presence of unmachined areas on the tooth surface 32 of the machining gear 3, thereby suppressing the occurrence of machining cracks and localized tensile residual stress.

[0023] Furthermore, the shape and arrangement of each projection 33 of the machining gear 3 may be set by adjusting the rotational speed of the machining gear 3 during machining and the machining pressure from the projections 33 (the pressing force that presses the machining gear 3 against the workpiece gear 2), so that the machining heat generated on the tooth surface 22 of the workpiece gear 2 is approximately 400°C to 500°C. This machining heat can facilitate plastic deformation of the tooth surface 22 of the workpiece gear 2.

[0024] Furthermore, the protrusions 33 may be arranged on the tooth surface 32 of the machining gear 3 so that plastic deformation is performed on the same portion of the tooth surface 22 of the workpiece gear 2 approximately 3,000 to 4,000 times per minute, depending on the desired rotational speed of the workpiece gear 2. This makes it possible to generate the heat generated during machining, and facilitates the plastic deformation of the tooth surface 22 of the workpiece gear 2.

[0025] Furthermore, the projection 33 has an approximately hemispherical shape, as shown in Figure 4. It is also preferable that the contact angle θ formed by a line L1 parallel to the direction of travel (rotational direction) of the projection 33 when the machining gear 3 rotates, and a tangent line L2 at the position on the spherical surface of the projection 33 where the projection 33 and the tooth surface 22 of the workpiece gear 2 are in contact, is 45° or less. The projection 33 is shaped such that the contact angle θ becomes smaller in areas where the projection 33 is embedded deeper into the tooth surface of the workpiece gear 2.

[0026] This allows for the formation of a projection 33 with a contact angle θ small enough to allow for optimal plastic deformation of the gear tooth surface 22 without cutting the tooth surface 22 of the gear 2 being worked on. However, as the tooth surface 22 of the gear tooth surface 22 is plastically deformed, there is a possibility that tearing, cracking, etc., may be induced on the tooth surface 22. For this reason, it is preferable that the contact angle θ is 45° or less and smaller.

[0027] The work hardening and residual stress depth of the tooth surface 22 of the workpiece gear 2, as imparted by the above processing, are determined by the embedding depth of the projection 33 of the processing gear 3 that is pressed into the tooth surface 22 of the workpiece gear 2, i.e., the depth to which plastic deformation occurs. Therefore, by controlling the size of the projection 33 of the processing gear 3 and the pressure of its indentation, a desired residual stress depth can be imparted to the tooth surface of the workpiece gear 2.

[0028] The projections 33 on the tooth surface 32 of the machining gear 3 described above allow for uniform plastic deformation of the outermost surface of the tooth surface 22 of the workpiece gear 2. Therefore, it is possible to improve hardness, refine the crystal structure, and impart high compressive residual stress to the vicinity of the surface of the workpiece gear 2, thereby improving the tooth root bending strength and tooth surface strength, and further reducing the coefficient of friction by mirroring the surface, thereby improving the transmission efficiency of the gear.

[0029] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of Symbols]

[0030] 1 Gear machining device, 2 Workpiece gear, 3 Machining gear, 21 Tooth, 22 Tooth surface, 31 Tooth, 32 Tooth surface, 33 Projection, 331 Tip

Claims

1. A gear machining apparatus for machining the tooth surface of a workpiece gear by rotating the workpiece gear while meshed with a machining gear, wherein projections are formed at the same position on the tooth surface of each tooth of the machining gear, and these projections contact the tooth surface of the workpiece gear. Gear machining equipment.

2. A gear processing apparatus according to claim 1, The projection is formed on the entire surface of the tooth surface of each tooth of the gear used for machining. Gear machining equipment.

3. A gear processing apparatus according to claim 1, The aforementioned projection has a spherical shape. Gear machining equipment.

4. A gear processing apparatus according to claim 3, The contact angle between the direction of travel of the projection when the machining gear rotates and the tangent line at the position on the spherical surface of the projection where it contacts the tooth surface of the gear being machined is 45° or less. Gear machining equipment.

5. A gear machining method in which the tooth surface of a workpiece gear is machined by rotating the workpiece gear while meshed with a machining gear, wherein projections are formed at the same position on the tooth surface of each tooth of the machining gear, and the projections contact the tooth surface of the workpiece gear. When the workpiece gear and the machining gear rotate, the projections on the tooth surfaces of each tooth of the machining gear continuously contact the same portion of the tooth surface of the workpiece gear. Gear manufacturing method.

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