JP7804873B2 - Gear manufacturing method and gear manufacturing device - Google Patents

Description

The present invention relates to a gear manufacturing method and gear manufacturing apparatus that uses multiple skiving cutters to cut a workpiece to manufacture gears.

Skiving, which uses a skiving cutter, is a well-known method for manufacturing gears. Patent Document 1 discloses a processing support device that supports the processing of workpieces 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 gear tooth flank shape modification elements: 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."

Japanese Patent Application Laid-Open No. 2021-11011

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

In light of these issues, the present invention aims to provide a gear manufacturing method and gear manufacturing device that can achieve the desired tooth profile accuracy when changing the tooth profile in the tooth trace direction of the workpiece during skiving.

To solve the above problems, a typical configuration of the gear manufacturing method according to the present invention is a gear manufacturing method that uses multiple skiving cutters to cut a workpiece to produce a gear, and is 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 with a thinner tooth thickness than the first cutter is used to cut the tooth flanks near the tip, one side at a time, in such a way that the crossing 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 with a thinner tooth thickness than the first cutter is used to cut the tooth flanks near the base, one side at a time, in such a way that the crossing 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.

To solve the above problems, a typical configuration of a gear manufacturing device according to the present invention is a gear manufacturing device that uses multiple skiving cutters to cut a workpiece, and includes a control unit that controls the operation of the gear manufacturing device, and skiving cutters that include a first cutter, a second cutter with a thinner tooth thickness than the first cutter, and a third cutter with a thinner tooth thickness than the first cutter. The control unit uses the first cutter to simultaneously cut both adjacent tooth flanks to form a first pressure angle, uses the second cutter to cut the tooth flanks near the tip, 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 tooth flanks near the base, 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.

The present invention provides a gear manufacturing method and gear manufacturing device that can achieve the desired tooth profile accuracy when changing the tooth profile in the tooth trace direction of the workpiece during skiving.

3A to 3C are diagrams illustrating the posture of the gear manufacturing apparatus according to the present embodiment during operation. 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. 2A to 2C are diagrams illustrating a gear manufacturing method using the gear manufacturing apparatus of FIG. 1. FIG. 2 is a schematic partial perspective view illustrating a tooth surface cutting position of the workpiece of FIG. 1 .

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 these embodiments are merely examples intended to facilitate understanding of the invention and, unless otherwise specified, do not limit the present invention. Furthermore, in this specification and drawings, elements having substantially the same function and configuration are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present invention will not be illustrated or described.

Figure 1 is a diagram illustrating the posture of the gear manufacturing apparatus 100 according to this embodiment during operation. Below, the gear manufacturing apparatus 100 shown in Figure 1 will be described in detail, 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.

As shown in Figure 1, in the gear manufacturing apparatus 100, the skiving cutter 200 is attached to a tool spindle (not shown) via a holder 102. The 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 operation of the skiving cutter 200 and chuck 104 is 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.

In particular, Figure 1 illustrates the posture of the gear manufacturing apparatus 100 during operation. When performing cutting, the control unit 110 controls the skiving cutter 200 and chuck 104, causing the workpiece 300 to rotate at a predetermined rotation speed around rotation axis A1 (rotation axis A1 is also referred to as the workpiece axis), and the skiving cutter 200 to rotate at a predetermined rotation speed around 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 the first processing step described below), which is the angle formed by the two rotation axes A1 and A2, the skiving cutter 200 moves from the top to the bottom as shown in Figure 1, cutting the workpiece 300 to produce a gear.

Figure 2 is a diagram explaining the specifications of the skiving cutter 200 used in the gear manufacturing method using the gear manufacturing apparatus 100 of Figure 1. As shown in Figure 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. The second and third processing steps involve cutting one side at a time by switching the cutter in the opposite direction, so if broken down further, they can be considered to be five processing steps in total. In Figure 2(a), α, β, γ, and a-h are predetermined positive values, and a plus (+) value relative to the reference value indicates a larger value, while a minus (-) value relative to the reference value indicates a smaller value.

The first cutter 210 used in the first machining process has a tooth thickness of reference tooth thickness t1, as shown in Figure 2(b). The first cutter 210 has the same specifications as a skiving cutter used for normal gear cutting.

As shown in Figure 2(b), the second cutter 220 used in the second machining process has a tooth thickness t2 that is set 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 (D-g).

As shown in Figure 2(c), the third cutter 230 used in the third machining process has a tooth thickness t3 that is set 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 (D - h). 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.

As explained above, the tooth thickness t2 of the second cutter 220 and the tooth thickness t3 of the third cutter 230 only need to 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.

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

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 the workpiece 300, as shown in Figure 3(a) (first processing step: normal gear cutting process). 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 and the tangent to the tooth profile at a point on the tooth flank, typically the pitch point) as the reference angle α (see Figure 2).

Next, as shown in Figure 3(b), the second cutter 220 is used to cut the tooth surfaces 302a and 302b near their tips, one at a time (second processing step: tooth tip cutting step). Specifically, in the second processing step, the second cutter 220 is used to cut the surface 304a near the tip of one of the tooth surfaces 302a and 302b (see Figure 4(a)), and the surface 304b near the tip of the other tooth surface (see Figure 4(b)).

In the second machining process described above, the crossing angle is changed to γ-e, which is smaller than in the first machining process, and maintained in this state, and the target helix angle is changed to β-c, which is smaller than in the first machining process, 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 (b), the inclination directions on the left and right sides of the tooth surface are opposite.

Then, as shown in Figure 3(c), the third cutter 230 is used to cut the tooth flanks 302a and 302b near the root on one side at a time (third processing step: root cutting step). Specifically, in the third processing step, the third cutter 230 is used to cut the surface 306a near the root on one side of the tooth flanks 302a and 302b (see Figure 4(a)), and the surface 306b near the root on the other side (see Figure 4(b)).

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

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

In this case, by maintaining a constant crossing angle (γ, γ-e, γ+f, respectively) in all three machining processes, the changes in the machining point and cutting resistance that accompany changes in the crossing angle can be suppressed. Therefore, because the machining point moves along the workpiece axis, it is possible to manufacture gears with the desired tooth profile accuracy.

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 a person skilled in the art could conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present invention.

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 the tooth tip, 304b... surface near the tooth tip, 306a... surface near the tooth base, 306b... surface near the tooth base, 310... tooth tip, 312... tooth root

Claims (2)

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: 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.