Gear manufacturing method and gear manufacturing device

Abstract

To provide a gear manufacturing method and a gear manufacturing apparatus which can obtain the desired tooth form accuracy when a tooth form is changed in a tooth trace direction of a workpiece in skiving processing.SOLUTION: A gear manufacturing method for manufacturing a gear by cutting a workpiece comprises: a first processing step of cutting tooth surfaces on both sides adjacent to each other simultaneously so as to have a first pressure angle by using a first cutter 210; a second processing step of cutting the vicinity of a tooth tip of the tooth surface one surface by one surface so as to have a second pressure angle larger than the first pressure angle by changing an intersecting angle and a torsion angle of the first processing step by using a second cutter 220 whose tooth thickness is processed to be thinner than the first cutter; and a third processing step of cutting the vicinity of a root of the tooth surface one surface by one surface so as to have a third pressure angle smaller than the first pressure angle by changing the intersecting angle and the torsion angle of the first processing step by using a third cutter 230 whose tooth thickness is processed to be thinner than the first cutter.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a gear manufacturing method and gear manufacturing apparatus for manufacturing gears by cutting a workpiece using a plurality of skiving cutters. [Background technology]

[0002] Skiving using a skiving cutter is a well-known method for manufacturing gears. Patent Document 1 discloses a processing support device that supports the processing of a workpiece during skiving. The processing support device in Patent Document 1 includes a "target modification amount memory unit that stores target modification amounts for at least two of the modification elements of the tooth flank shape of a gear tooth, namely crowning, bias, helix angle, pressure angle, and tooth profile roundness," and a "correction amount determination unit that determines correction amounts for processing control elements during processing operations so that at least two of the modification elements approximate the target modification amounts stored in the target modification amount memory unit." [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-11011 Summary of the Invention [Problem to be solved by the invention]

[0004] When changing the tooth profile in the tooth trace direction of the workpiece during skiving, it is necessary to change the helix angle and offset angle while performing the skiving cutting feed (processing operation), i.e., to change the processing operation, as in Patent Document 1. However, changes in the intersection angle and offset angle cause changes in the processing point and cutting resistance, making it difficult to obtain the desired tooth profile accuracy.

[0005] In view of these problems, the present invention aims to provide a gear manufacturing method and gear manufacturing apparatus that can obtain the desired tooth profile accuracy when changing the tooth profile in the tooth trace direction of the workpiece during skiving. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, a representative configuration of a gear manufacturing method according to the present invention is a gear manufacturing method in which a workpiece is cut using a plurality of skiving cutters to manufacture gears, characterized by having: a first machining step in which a first cutter is used to simultaneously cut both adjacent tooth flanks to form a first pressure angle; a second machining step in which a second cutter having a thinner tooth thickness than the first cutter is used to cut the tooth flanks in the vicinity of the tip, one side at a time, in such a way that the crossover angle and helix angle of the first machining step are changed to form a second pressure angle that is larger than the first pressure angle; and a third machining step in which a third cutter having a thinner tooth thickness than the first cutter is used to cut the tooth flanks in the vicinity of the base, one side at a time, in such a way that the crossover angle and helix angle of the first machining step are changed to form a third pressure angle that is smaller than the first pressure angle.

[0007] In order to solve the above problems, a representative configuration of a gear manufacturing apparatus according to the present invention is a gear manufacturing apparatus that cuts a workpiece using a plurality of skiving cutters, and includes a control unit that controls the operation of the gear manufacturing apparatus, and skiving cutters that include a first cutter, a second cutter having a thinner tooth thickness than the first cutter, and a third cutter having a thinner tooth thickness than the first cutter, and the control unit is characterized in that it uses the first cutter to cut both adjacent tooth flanks simultaneously to form a first pressure angle, uses the second cutter to cut the vicinity of the tip of the tooth flanks one side at a time by changing the crossing angle and helix angle to form a second pressure angle that is larger than the first pressure angle, and uses the third cutter to cut the vicinity of the root of the tooth flanks one side at a time by changing the crossing angle and helix angle to form a third pressure angle that is smaller than the first pressure angle. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a gear manufacturing method and gear manufacturing apparatus that can obtain the desired tooth profile accuracy when changing the tooth profile in the tooth trace direction of the workpiece during skiving. [Brief explanation of the drawings]

[0009] [Figure 1] 3A to 3C are diagrams illustrating the posture of the gear manufacturing apparatus according to the present embodiment during operation. [Figure 2] FIG. 2 is a diagram illustrating the specifications of a skiving cutter used in a gear manufacturing method using the gear manufacturing apparatus of FIG. 1. [Figure 3] 2A to 2C are diagrams illustrating a gear manufacturing method using the gear manufacturing apparatus of FIG. 1. [Figure 4] FIG. 2 is a schematic partial perspective view illustrating a tooth surface cutting processing position of the workpiece in FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0010] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Dimensions, materials, and other specific values ​​shown in the embodiments are merely examples for facilitating understanding of the invention and, unless otherwise specified, do not limit the present invention. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present invention are not shown or described.

[0011] Figure 1 is a diagram illustrating the posture of a gear manufacturing apparatus 100 according to this embodiment during operation. The gear manufacturing apparatus 100 shown in Figure 1 will be described in detail below, along with a gear manufacturing method according to this embodiment. The gear manufacturing apparatus 100 according to this embodiment and the gear manufacturing method using it manufacture bias-in gears (gears whose pressure angle changes in the face width direction) by cutting a workpiece using multiple skiving cutters 200.

[0012] As shown in Figure 1, in a gear manufacturing apparatus 100, a skiving cutter 200 is attached to a tool spindle (not shown) via a holder 102. A workpiece 300 is held in a chuck 104 and is cut while rotating in synchronization with the skiving cutter 200. In the gear manufacturing apparatus 100 of this embodiment, the operations of the skiving cutter 200 and the chuck 104 are controlled by a control unit 110. In reality, as shown in Figures 2 and 3 described below, multiple skiving cutters are indicated by the reference numerals 210, 220, and 230, but in Figure 1 they are shown as skiving cutter 200 for ease of explanation.

[0013] 1 in particular illustrates an example of the posture of the gear manufacturing apparatus 100 during operation. When performing cutting, the control unit 110 controls the skiving cutter 200 and the chuck 104, so that the workpiece 300 rotates at a predetermined rotation speed around a rotation axis A1 (rotation axis A1 is also referred to as the workpiece axis), and the skiving cutter 200 also rotates at a predetermined rotation speed around a rotation axis A2 (rotation axis A2 is also referred to as the tool axis). Then, while maintaining the crossing angle γ (in the case of a first processing step, which will be described later) formed by the two rotation axes A1 and A2, the skiving cutter 200 moves from the upward direction to the downward direction as shown in FIG. 1, thereby cutting the workpiece 300 and manufacturing a gear.

[0014] FIG. 2 is a diagram illustrating the specifications of a skiving cutter 200 used in a gear manufacturing method using the gear manufacturing apparatus 100 of FIG. 1. As shown in FIG. 2(a), the gear manufacturing method of this embodiment involves a first processing step (similar to normal gear cutting) in which both tooth flanks are cut simultaneously, a second processing step in which the tooth tip vicinity is cut one side at a time, and a third processing step in which the tooth base vicinity is cut one side at a time. Because the second and third processing steps involve cutting one side at a time by switching the cutter in the opposite direction, the process can be considered to consist of five processing steps in total. In FIG. 2(a), α, β, γ, and a to h are predetermined positive values, and a plus (+) sign relative to the reference value indicates a larger value, while a minus (-) sign relative to the reference value indicates a smaller value.

[0015] The first cutter 210 used in the first machining step has a tooth thickness of reference tooth thickness t1 as shown in Fig. 2(b). The first cutter 210 has the same specifications as a skiving cutter used for normal gear cutting.

[0016] As shown in Fig. 2(b), the second cutter 220 used in the second machining step has a tooth thickness t2 that is set to be thinner than the reference tooth thickness t1 (t1>t2). The tooth depth d2 of the second cutter 220 is smaller than the tooth depth d1 of the first cutter 210 (d1>d2). Furthermore, the cutter diameter of the second cutter 220 is smaller than the cutter diameter D of the second cutter 220 (Dg).

[0017] As shown in FIG. 2(c), the third cutter 230 used in the third machining step has a tooth thickness t3 that is set to be thinner than the reference tooth thickness t1 (t1>t3). The tooth depth d3 of the third cutter 230 is greater than the tooth depth d1 of the first cutter 210 (d3>d1). However, the cutter diameter of the third cutter 230 is smaller than the cutter diameter D of the second cutter 220 (Dh). This is to prevent the tip of the third cutter 230 from coming into contact with the tooth bottom 312 of the workpiece 300 when the center distance between the workpiece 300 and the first cutter 210 and the center distance between the workpiece 300 and the third cutter 230 are the same.

[0018] As explained above, the tooth thickness t2 of the second cutter 220 and the tooth thickness t3 of the third cutter 230 need only be thinner than the reference tooth thickness t1 of the first cutter 210, and the relationship between the tooth thickness t2 of the second cutter 220 and the tooth thickness t3 of the third cutter 230 may be determined arbitrarily.

[0019] Fig. 3 is a diagram illustrating a gear manufacturing method using the gear manufacturing apparatus 100 of Fig. 1. Fig. 4 is a schematic partial perspective view illustrating the tooth surface cutting processing position of the workpiece 300 of Fig. 1, Fig. 4(a) shows the left side and Fig. 4(b) shows the right side.

[0020] In the gear manufacturing method of this embodiment, first, while maintaining the crossing angle γ, the first cutter 210 is used to simultaneously cut the tooth root 312 and the adjacent tooth flanks 302a and 302b on both sides of the workpiece 300 as shown in Figure 3(a) (first processing step: normal gear cutting step). The crossing angle at this time is defined as γ, the target helix angle as β, and the pressure angle (the angle between the radius of a point on the tooth flank, typically the pitch point, and the tangent to the tooth profile at that point) as the reference angle α (see Figure 2).

[0021] Next, as shown in Fig. 3(b), the tooth flanks 302a and 302b are cut one by one near the tip (second processing step: tooth tip cutting step) using the second cutter 220. More specifically, in the second processing step, the second cutter 220 is used to cut one of the tooth flanks 302a and 302b, a surface 304a near the tip (see Fig. 4(a)), and the other surface 304b near the tip (see Fig. 4(b)).

[0022] In the second machining step described above, the crossing angle is changed to γ-e, which is smaller than in the first machining step, and maintained in this state, and the target helix angle is changed to β-c, which is smaller than in the first machining step, so that the pressure angle is larger than the reference angle α (α+a) (see Figure 2). As a result, surfaces 304a and 304b near the tooth tip are cut obliquely (tooth tip 310 is also cut obliquely), but as shown in Figures 4(a) and 4(b), the inclination directions on the left and right sides of the tooth flank are opposite.

[0023] Then, as shown in Fig. 3(c), the tooth flanks 302a and 302b are cut one by one near the root using the third cutter 230 (third processing step: root cutting step). More specifically, in the third processing step, the third cutter 230 is used to cut one of the tooth flanks 302a and 302b near the root, a surface 306a (see Fig. 4(a)) and the other surface 306b (see Fig. 4(b)) near the root.

[0024] In the third machining step, the crossing angle is changed to γ+f, which is larger than that in the first machining step, and maintained in this state, while the target helix angle is changed to β+d, which is larger than that in the first machining step, so that the pressure angle becomes smaller than the reference angle α (α-b) (see Figure 2). As a result, the surfaces 306a and 306b near the root are cut obliquely, but as shown in Figures 4(a) and 4(b), the inclination directions are opposite on the left and right sides of the tooth surface.

[0025] As described above, in the gear manufacturing apparatus 100 and gear manufacturing method of this embodiment, a plurality of skiving cutters (first cutter 210, second cutter 220, and third cutter 230) with different pressure angles and tooth thicknesses are used to cut the workpiece 300. This makes it possible to manufacture bias-in gears with pressure angles that vary in the face width direction.

[0026] By maintaining a constant crossing angle (γ, γ-e, γ+f) in each of the first, second, and third machining steps, it is possible to suppress changes in the machining point and cutting resistance that accompany changes in the crossing angle. As a result, the machining point moves along the workpiece axis, making it possible to manufacture gears with the desired tooth profile accuracy.

[0027] While 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 these examples. It is clear that those skilled in the art can conceive of various modifications and alterations within the scope of the claims, and it is understood that these modifications and alterations also fall within the technical scope of the present invention. [Explanation of symbols]

[0028] 100... gear manufacturing device, 102... holder, 104... chuck, 110... control unit, 200... skiving cutter, 210... first cutter, 220... second cutter, 230... third cutter, 300... workpiece, 302a... tooth surface, 302b... tooth surface, 304a... surface near tooth tip, 304b... surface near tooth tip, 306a... surface near tooth base, 306b... surface near tooth base, 310... tooth tip, 312... tooth root

Claims

1. A gear manufacturing method for manufacturing a gear by cutting a workpiece using a plurality of skiving cutters, comprising: a first machining step of simultaneously cutting both adjacent tooth flanks using a first cutter so that the tooth flanks have a first pressure angle; a second machining step of cutting the vicinity of the tooth tip of each tooth flank one side at a time using a second cutter having a thinner tooth thickness than the first cutter to change the crossing angle and the helix angle from the crossing angle and the helix angle of the first machining step to angles different from the crossing angle and the helix angle of the first machining step, thereby forming a second pressure angle larger than the first pressure angle; a third machining step of cutting the vicinity of the root of the tooth flanks one side at a time using a third cutter having a thinner tooth thickness than the first cutter to change the crossing angle and the helix angle from the crossing angle and the helix angle of the first machining step to angles different from the crossing angle and the helix angle of the first machining step, so as to obtain a third pressure angle smaller than the first pressure angle; A gear manufacturing method comprising the steps of:

2. A gear manufacturing apparatus that cuts a workpiece using a plurality of skiving cutters, a control unit that controls the operation of the gear manufacturing apparatus; The skiving cutter includes a first cutter, a second cutter having a tooth thickness thinner than that of the first cutter, and a third cutter having a tooth thickness thinner than that of the first cutter; Equipped with The control unit cutting both adjacent tooth flanks simultaneously using the first cutter so that the tooth flanks have a first pressure angle; cutting the tooth flanks near the tips one side at a time using the second cutter to change the crossing angle and the helix angle to a second pressure angle larger than the first pressure angle; a third cutter is used to change the crossing angle and the helix angle to cut the vicinity of the root of each tooth flank, one side at a time, so as to obtain a third pressure angle which is smaller than the first pressure angle.

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