Roller Burnishing Tool

Abstract

To burnish a workpiece with high precision even if the workpiece has a concave portion.SOLUTION: A roller burnishing tool 10 includes a plurality of rollers 16 arranged so that when rotated about a rotation axis X, contact points in contact with a workpiece 20, of the rollers draw the same locus. The plurality of rollers 16 are configured such that at least one of positions of other rollers 16 when one roller 16 is at a predetermined position is different from positions of other rollers 16 when one of the other rollers 16 is at a predetermined position. Specifically, the plurality of rollers 16 are arranged such that an angle formed by two lines extending from the contact point of one pair of rollers 16 toward the rotation axis X among a plurality of adjacent pairs of the rollers 16 is different from that of the other pair of rollers 16.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a roller burnishing tool, and more particularly to a roller burnishing tool having a plurality of rollers arranged so that the contact points with the workpiece follow the same locus when the tool rotates about a rotation axis. [Background technology]

[0002] A roller burnishing tool equipped with multiple rollers is used to burnish the inner periphery of a cylindrical or truncated cone-shaped opening in a workpiece (hereinafter referred to as "work") (see Patent Document 1). In such a roller burnishing tool, the multiple rollers are arranged so that the contact points with the workpiece trace the same trajectory when the tool rotates around the rotation axis. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-038049 Summary of the Invention [Problem to be solved by the invention]

[0004] A workpiece may have a recess such as a key groove. When such a recess exists, one of the rollers cannot come into contact with the workpiece when it is positioned in the recess. As a result of the inventor's diligent research and development, it was found that when one roller is positioned in the recess, it affects the accuracy of the burnishing process by the other rollers.

[0005] The present invention has been made in view of the above-mentioned problems, and has as its object to burnish a workpiece with high precision even when the workpiece has a recessed portion. [Means for solving the problem]

[0006] In order to solve the above problem, a roller burnishing tool according to the present invention includes a plurality of rollers arranged so that contact points with a workpiece follow the same locus when the rollers rotate about a rotation axis, The plurality of rollers are arranged so that when one roller is in a predetermined position, the position of at least one of the other rollers is different from the position of another roller when the other roller is in the predetermined position.

[0007] As a result of diligent research and development by the inventors, it was found that the above configuration can reduce the influence of other rollers on the burnishing process when one roller is in a recessed portion. Therefore, according to this aspect, even if the workpiece has a recessed portion, the workpiece can be burnished with high precision.

[0008] The plurality of rollers may be arranged such that when one roller is in a predetermined position, the positions of all of the other rollers are different from the positions of the other rollers when another roller is in the predetermined position. According to this aspect, the influence of the other rollers on the burnishing process when one roller is in the recessed portion can be further reduced.

[0009] The plurality of rollers may be arranged such that when each roller is in a predetermined position, the positions of the other rollers are all different from one another. According to this aspect, when one roller is in the recessed portion, the position of the other rollers is always different from the position of the other rollers when another roller is in the recessed portion. Therefore, according to this aspect, the influence of the other rollers on the burnishing process when one roller is in the recessed portion can be further reduced.

[0010] The rollers may be arranged such that the angle formed by two lines extending from the contact point of one pair of rollers to the rotation shaft among adjacent pairs of rollers is different from that of the other pairs of rollers. Furthermore, the angles formed by the two lines extending from the contact point of one pair of rollers to the rotation shaft among adjacent pairs of rollers may be different from those of the other pairs of rollers. According to this aspect, even if the workpiece has a recess, the workpiece can be burnished with high precision with such a simple configuration. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 10 is a side view of a roller burnishing tool according to a comparative example. [Figure 2] 2 is a cross-sectional view taken along the line AA in FIG. 1. [Figure 3] FIG. 10 is a schematic cross-sectional view showing a state in which a roller burnishing tool according to a comparative example is inserted into a workpiece. [Figure 4] FIG. 10 is a schematic cross-sectional view showing a state in which a roller burnishing tool according to a comparative example is inserted into a workpiece. [Figure 5] (a) is a schematic cross-sectional view showing the state in which a roller burnishing tool according to a comparative example is inserted into a workpiece. (b) is a table showing the arrangement angles of the rollers in the roller burnishing tool according to the comparative example. (c) is a table showing the surface roughness at five measurement points on five workpieces after burnishing using the roller burnishing tool according to the comparative example. (d) is a graph of (c). [Figure 6] (a) is a schematic cross-sectional view showing the state in which a roller burnishing tool according to a first embodiment of the present invention is inserted into a workpiece. (b) is a table showing the arrangement angles of the rollers in the roller burnishing tool according to the first embodiment. (c) is a table showing the surface roughness at five measurement points on five workpieces after burnishing using the roller burnishing tool according to the first embodiment. (d) is a graph of (c). [Figure 7] 10(a) to 10(g) are diagrams showing the positions of rollers when one roller is in a keyway in the roller burnishing tool according to the first embodiment. [Figure 8] 3 is a diagram showing the position of one roller when the other roller is in a key groove in the roller burnishing tool according to the first embodiment. FIG. [Figure 9] 1(a) is a schematic cross-sectional view showing a state in which a roller burnishing tool according to a second embodiment is inserted into a workpiece, and FIG. 1(b) is a table showing the arrangement angles of the rollers in the roller burnishing tool according to the second embodiment. [Figure 10] FIG. 10 is a diagram showing the position of one roller when the other roller is in a key groove in the roller burnishing tool according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] (Comparative Example) Fig. 1 is a side view of a roller burnishing tool 10 according to a comparative example. As can be seen from Fig. 1, the roller burnishing tool 10 is formed in a tapered truncated cone shape so that the diameter becomes smaller as it approaches the tip. In the comparative example, the taper is 1 / 10, but the degree of taper is of course not limited to this.

[0013] 2 is a cross-sectional view taken along line AA in FIG. 1. The roller burnishing tool 10 has a frame 12, a main body 14, and a plurality of rollers 16. The main body 14 is formed in a solid truncated cone shape. The frame 12 is formed in a hollow truncated cone shape so that it can be fitted into the main body 14. The main body 14 is formed with a plurality of openings 12a extending in the direction of the rotation axis X. The plurality of rollers 16 are inserted into these openings 12a. When the main body 14 is inserted into the frame 12 with the rollers 16 inserted into the openings 12a, the rollers 16 are rotatably supported. Such a method of supporting the rollers 16 is well known, so a detailed description thereof will be omitted.

[0014] Although the roller burnishing tool 10 according to the comparative example has six rollers 16, the number of rollers 16 is not limited to six. Hereinafter, in a cross-sectional view of the roller burnishing tool 10 viewed toward the tip, if there are k rollers 16, the rollers 16 will be referred to clockwise as roller R1, roller R2, ..., roller Rk. The rollers 16 are arranged so that when the rollers 16 rotate around the rotation axis X, the contact points with the workpiece 20 (hereinafter simply referred to as "contact points") trace the same trajectory. Specifically, the rollers 16 are arranged so that the surface of the truncated cone-shaped roller burnishing tool 10 and its central axis are parallel and so that the central axis intersects with the rotation axis X.

[0015] The roller burnishing tool 10 is configured to be rotatable about a rotation axis X. A rotary actuator (not shown) is provided to rotate the roller burnishing tool 10, and the roller burnishing tool 10 is rotationally driven by this rotary actuator. A pressing mechanism (not shown) is also provided to press the roller burnishing tool 10 toward its tip, and the roller burnishing tool 10 is rotationally driven while pressed against a workpiece by this pressing mechanism. This configuration of the roller burnishing tool 10 is well known, so a detailed description will be omitted.

[0016] 3 is a schematic cross-sectional view showing a state in which a roller burnishing tool 10 according to a comparative example is inserted into a workpiece. In the comparative example, the workpiece 20 to be machined by the roller burnishing tool 10 is a flywheel attached to a crankshaft of a vehicle. However, it goes without saying that the workpiece 20 is not limited to a flywheel.

[0017] In the flywheel, the inner peripheral surface of the axial hole 20a is the target area for burnishing. The rollers 16 of the workpiece 20 come into contact with the inner peripheral surface of the axial hole 20a of the workpiece 20 at the radially outermost line on their outer peripheral surfaces, which is the farthest from the rotation axis X. However, many flywheels are formed with keyways 20b for non-rotatable attachment to the crankshaft. Therefore, when the rollers 16 pass through the keyways 20b, they cannot come into contact with the inner peripheral surface of the axial hole 20a of the workpiece 20. Therefore, when the rollers 16 pass through the keyways 20b, five rollers 16, not six, come into contact with the inner peripheral surface of the axial hole 20a of the workpiece 20, which increases the processing load per roller.

[0018] 4 is a schematic cross-sectional view showing a state in which a roller burnishing tool 10 according to a comparative example is inserted into a workpiece. As shown in FIG. 4, the angle formed by a line extending from the contact point of roller R1 to the rotation axis X and a line extending from the contact point of roller R2 to the rotation axis X is defined as θ1. The angle formed by a line extending from the contact point of roller R2 to the rotation axis X and a line extending from the contact point of roller R3 to the rotation axis X is defined as θ2. Similarly, the angles formed by the rollers R k A line extending from the contact point of the roller R to the rotation axis X k+1 The angle formed by the line extending from the contact point to the rotation axis X is θ k In the roller burnishing tool 10 according to the comparative example, θ k All are 60°.

[0019] 4 indicates the area in the comparative example where one roller 16 rolls on the inner circumferential surface of the shaft hole 20a when the other roller 16 passes through the key groove 20b. In this way, the comparative example has a narrower hatched area Y.

[0020] Fig. 5(a) is a schematic cross-sectional view showing a state in which the roller burnishing tool 10 according to the comparative example is inserted into a workpiece. Fig. 5(b) is a table showing the arrangement angles of the rollers in the roller burnishing tool 10 according to the comparative example. As shown in Figs. 5(a) and 5(b), in the roller burnishing tool 10 according to the comparative example, θ k All are 60°.

[0021] Fig. 5(c) is a table showing the surface roughness at five measurement points of five workpieces after burnishing using the roller burnishing tool 10 according to the comparative example. Fig. 5(d) is a graph of Fig. 5(c). Using this comparative example 10, the inner surfaces of the shaft holes 20a of five workpieces 20 were burnished, and a test was conducted to measure the surface roughness Ra of the inner surfaces of the shaft holes 20a of the five workpieces 20 after burnishing.

[0022] As shown in Figures 5(a) and 5(c), the surface roughness Ra was measured at five measurement points P1 to P5. The reference position P0 is the position of the roller 16 when it is in the center of the keyway 20b. The first measurement point P1, the third measurement point P3, and the fifth measurement point P5 are points on the inner surface of the shaft hole 20a of the workpiece 20 that one roller 16 comes into contact with when the other roller 16 is in the reference position P0. On the other hand, the second measurement point P2 and the fourth measurement point P4 are points on the inner surface of the shaft hole 20a of the workpiece 20 that one roller 16 does not come into contact with when the other roller 16 is in the reference position P0.

[0023] 5(c) and (d), it can be seen that the surface roughness Ra increases at the third measurement point P3. The third measurement point P3 is located just opposite the keyway 20b. Therefore, it is expected that the increase in surface roughness Ra at the third measurement point P3 is due to the influence of the keyway 20b.

[0024] (First Example) The roller burnishing tool 10 according to the first embodiment of the present invention is similar to the roller burnishing tool 10 according to the comparative example, except for the number and arrangement of the rollers 16. FIG. 6(a) is a schematic cross-sectional view showing the roller burnishing tool 10 according to the first embodiment inserted into a workpiece. FIG. 6(b) is a table showing the arrangement angles of the rollers in the roller burnishing tool 10 according to the first embodiment. As shown in FIGS. 6(a) and 6(b), seven rollers 16 are provided in the first embodiment. In addition, θ k The seven rollers 16 are arranged so that they are not uniform but different from each other.

[0025] In the first embodiment, the rollers 16 are arranged at unequal intervals. Specifically, in the first embodiment, the rollers 16 are arranged such that when one roller 16 is at the reference position P0, the positions of all of the other rollers 16 are different from the positions of the other rollers 16 when the other rollers 16 are at the reference position P0. Even more specifically, the rollers 16 are arranged such that when each roller 16 is at the reference position P0, the positions of the other rollers 16 are different from one another.

[0026] In other words, the rollers 16 are arranged such that the angle θ between two lines extending from the contact points of a pair of rollers 16 to the rotation axis X is θ . k are arranged differently from other pairs of rollers 16. And, θ between all adjacent pairs of rollers 16 k are different from each other.

[0027] 6(a) and 6(c), the surface roughness Ra was also measured at five measurement points P1 to P5. The first measurement point P1 and the fifth measurement point P5 are locations on the inner circumferential surface of the shaft hole 20a of the workpiece 20 where one roller 16 comes into contact when the other roller 16 is at the reference position P0. Meanwhile, the second measurement point P2, the third measurement point P3, and the fourth measurement point P4 are locations on the inner circumferential surface of the shaft hole 20a of the workpiece 20 where one roller 16 does not come into contact when the other roller 16 is at the reference position P0.

[0028] FIG. 6(c) is a table showing the surface roughness at five measurement points of five workpieces after burnishing using the roller burnishing tool 10 according to the first embodiment. FIG. 6(d) is a graph of FIG. 6(c). FIGS. 6(c) and 6(d) show that the surface roughness Ra at the third measurement point P3 is significantly reduced compared to the comparative example. Therefore, it can be seen that the surface roughness Ra of the workpiece can be improved by arranging the multiple rollers 16 so that when one roller 16 is at the reference position P0, the positions of all of the other rollers 16 are different from the positions of the other rollers 16 when the other rollers 16 are at the reference position P0.

[0029] 7(a) to 7(g) are diagrams showing the positions of the other rollers 16 when one roller 16 is in the keyway in the roller burnishing tool 10 according to the first embodiment. For example, FIG. 7(a) is a diagram showing the arrangement of the other rollers 16 when roller R1 is in the reference position P0. FIG. 7(b) is a diagram showing the arrangement of the other rollers 16 when roller R2 is in the reference position P0. As shown in FIGS. 7(a) and 7(b), the positions of rollers R2 to R7 when roller R1 is in the reference position P0 are different from the positions of rollers R3 to R7 and R1 when roller R2 is in the reference position P0. The positions of the other rollers 16 when roller R2 is in the reference position P0 are different from the positions of the other rollers 16 when roller R3 is in the reference position P0. In this way, the positions of the other rollers 16 when one roller 16 is in the reference position P0 are different from the positions of the other rollers 16 when the other roller 16 is in the reference position P0. Furthermore, in the first embodiment, the plurality of rollers 16 are arranged so that when each roller 16 is at the reference position P0, the positions of the other rollers 16 are all different from one another.

[0030] FIG. 8 is a diagram showing the positions of the other rollers when one roller is in the keyway in the roller burnishing tool 10 according to the first embodiment, and is a superimposed view of FIGS. 7(a) to 7(g). In this way, in the first embodiment, the multiple rollers 16 are arranged so that when each roller 16 is in the reference position P0, the positions of the other rollers 16 are all different from one another. Therefore, the range of movement of the other rollers 16 when each roller 16 passes through the keyway 20b, represented by the hatched area outside the inner circumferential surface of the axial hole 20a of the workpiece 20 in FIG. 8, is much wider than in the comparative example shown in FIG. 4. Therefore, the influence of the other rollers 16 on the burnishing process when the roller 16 passes through the keyway 20b can be dispersed, and a decrease in the burnishing accuracy when the workpiece 20 has the keyway 20b can be suppressed.

[0031] (Second Example) The roller burnishing tool 10 according to the second embodiment is similar to the roller burnishing tool 10 according to the comparative example, except for the arrangement of the rollers 16. FIG. 9(a) is a schematic cross-sectional view showing the roller burnishing tool 10 according to the second embodiment inserted into a workpiece. FIG. 9(b) is a table showing the arrangement angles of the rollers in the roller burnishing tool according to the second embodiment. In the second embodiment as well, the multiple rollers 16 are arranged at unequal intervals. Specifically, in the second embodiment as well, the multiple rollers 16 are arranged so that when each roller 16 is at the reference position P0, the positions of all the other rollers 16 are different from each other. In other words, in the second embodiment as well, the θ between adjacent pairs of rollers 16 is k are different from each other.

[0032] FIG. 10 is a diagram showing the positions of the other rollers 16 when one roller 16 is in the keyway 20b in the roller burnishing tool 10 according to the second embodiment. Thus, in the second embodiment, the rollers 16 are also arranged such that the positions of the other rollers 16 are all different when each roller 16 is in the reference position P0. Therefore, the range of movement of the other rollers 16 when each roller 16 passes through the keyway 20b, represented by the shaded area outside the inner circumferential surface of the axial hole 20a of the workpiece 20 in FIG. 10, is much wider than in the comparative example shown in FIG. 4. Therefore, the influence of the other rollers 16 on the burnishing process when the roller 16 passes through the keyway 20b can be dispersed, and a decrease in the burnishing accuracy when the workpiece 20 has the keyway 20b can be suppressed.

[0033] Although the present invention has been described above with reference to the embodiments, the present invention is not limited to the above-described embodiments, and suitable combinations and substitutions of the configurations of the embodiments are also included in the present invention. Furthermore, it is possible to appropriately rearrange the combinations and processing orders in the embodiments based on the knowledge of a person skilled in the art, and to make modifications to the embodiments, such as various design changes, and such modified embodiments are also included in the scope of the present invention.

[0034] In one modified example, the multiple rollers 16 are arranged so that when one roller 16 is at the reference position P0, the position of at least one of the other rollers 16 is different from the position of the other roller 16 when the other roller 16 is at the reference position P0. Even if the multiple rollers 16 are not arranged so that all of the other rollers 16 are at different positions from each other when each roller 16 is at the reference position P0 in this manner, the effect of the key grooves 20b on the surface roughness Ra can be suppressed.

[0035] In another modified example, the roller burnishing tool 10 burnishes the outer peripheral surface of a cylindrical member such as a shaft, rather than the inner peripheral surface of a hole such as the shaft hole 20a. Therefore, multiple rollers are arranged on the inner peripheral surface of the cylindrical member. This allows the outer peripheral surface to be burnished with high precision even if the outer peripheral surface of the cylindrical member has a recess such as a key groove. [Explanation of symbols]

[0036] 10 roller burnishing tool, 12 frame, 14 main body, 16 roller, 20 workpiece, 20a shaft hole, 20b keyway

Claims

1. A plurality of rollers are arranged so that the contact points with the workpiece follow the same trajectory when the rollers rotate around the rotation axis.

1. A roller burnishing tool, comprising: a plurality of rollers arranged such that when a first roller is in a predetermined position, the position of at least one roller other than the first roller is different from the positions of all rollers other than the second roller when the second roller is in the predetermined position.

2. 2. The roller burnishing tool according to claim 1, wherein the plurality of rollers are arranged such that when the first roller is in a predetermined position, the positions of all rollers other than the first roller are different from the positions of all rollers other than the second roller when the second roller is in the predetermined position.

3. A plurality of rollers are arranged so that the contact points with the workpiece follow the same trajectory when the rollers rotate around the rotation axis. The roller burnishing tool is characterized in that the plurality of rollers are arranged such that an angle formed by two lines extending from the contact point of one pair of rollers to the rotation axis among adjacent pairs of rollers is different from that of another pair of rollers.

4. 4. The roller burnishing tool of claim 3, wherein the angles of all adjacent pairs of rollers are different from each other.

5. A method for manufacturing a workpiece, comprising the step of burnishing a workpiece with the roller burnishing tool according to any one of claims 1 to 4.

6. the workpiece includes a cylindrical or frusto-conical opening; 6. The method for manufacturing a workpiece according to claim 5, further comprising the step of burnishing the inner periphery of the opening with the roller burnishing tool.

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