JP2017131923A - Rolling device of screw - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rolling device of a screw capable of restraining accuracy reduction in a screw groove formed of a plurality of rolling dies.SOLUTION: A rolling device comprises a holding collar 12 for inserting a rod-like work 11 and a plurality of rolling dies 13 arranged at an equal interval in the circumferential direction around the axis of the work 11 held by the holding collar 12. These rolling dies 13 extend in parallel to the axis of the work 11 held by the holding collar 12. A plurality of crest parts 14 for forming a screw groove on an outer peripheral surface of the work 11 are fixed at a constant interval in the axial direction of the work 11 on an outer peripheral surface of the rolling die 13. A position of the crest parts 14 in the axial direction of the work 11 is different with every rolling die 13. The rolling device also comprises a plurality of rollers 15 for supporting the work 11 by abutting on the outer peripheral surface of its work 11 when forming the screw groove on the outer peripheral surface of the work 11 held by the holding collar 12.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a thread rolling device.

  As a method of rolling the thread groove of a ball screw, while rotating a plurality of rolling dies that are parallel to each other, a rod-shaped workpiece is passed between the rolling dies, and the rod-shaped workpiece is moved by the rotating rolling die. A rolling method called step rolling (through rolling) in which a thread groove is plastically processed on the outer peripheral surface of the workpiece while moving in the axial direction is known (see Patent Document 1).

  As shown in FIG. 4, the thread rolling device for performing such step rolling is centered on the holding collar 52 into which the rod-shaped workpiece 51 is inserted, and the axis of the workpiece 51 (the one-dot chain line L1 in FIG. 4). And a plurality (one pair in the example of FIG. 4) of rolling dies 53 that are arranged at equal intervals in the circumferential direction and extend in parallel with the axis of the work 51. Further, a crest 54 for forming a screw groove on the outer peripheral surface of the work 51 is fixed to the outer peripheral surface of the rolling die 53, and the position of the work 51 in the axial direction on the crest 54 is as follows. Different for each rolling die 53.

  Then, while rotating the plurality of rolling dies 53, the workpiece 51 held by the holding collar 52 and the respective rolling dies 53 are moved relative to each other in the axial direction, so that the above-mentioned between the rolling dies 53 is performed. When the workpiece 51 is sandwiched, the crest portion 54 of the rolling die 53 is pressed against the outer peripheral surface of the workpiece 51 to form a thread groove. Specifically, with relative movement of the workpiece 51 and each rolling die 53 in the axial direction, a peak portion 54 provided on one rolling die 53 and a peak portion provided on the other rolling die 53. 54 are alternately pressed against the outer peripheral surface of the workpiece 51 in order from the one located on the left side of FIG. 4, thereby forming a thread groove on the outer peripheral surface of the workpiece 51.

Japanese Unexamined Patent Publication No. 2000-51984

  As shown in FIG. 5, when forming a thread groove on the outer peripheral surface of the workpiece 51, the peak portion 54 located on the leftmost side of the rolling die 53 on one side (the lower side in FIG. 5) Is pressed against the outer peripheral surface of the workpiece 51, and then, the leftmost peak portion 54 of the other rolling die 53 (upper side in FIG. 5) is pressed against the outer peripheral surface of the work 51.

  However, from the time when the first peak 54 is pressed against the outer peripheral surface of the workpiece 51 to the time when the next peak 54 is pressed, only the peak 54 pressed first against the workpiece 51 is the same. A large load acts in a direction perpendicular to the axis of the workpiece 51. Although the workpiece 51 is held by the holding collar 52, when a large load is applied as described above, it is inevitable that the workpiece 51 is inclined in the direction of the arrow in FIG.

  Accordingly, after the first peak portion 54 is pressed against the outer peripheral surface of the work 51, until the next peak portion 54 is pressed, the outer peripheral surface of the work 51 remains inclined as described above. On the other hand, the thread groove is formed by the peak portion 54 pressed first. For this reason, the lead of the thread groove formed with the workpiece 51 tilted becomes a value (lead A) deviated from the appropriate value (lead B), and the accuracy of the thread groove in the ball screw is lowered.

  In FIG. 6, the solid line L2 indicates the state of the thread groove when the lead of the thread groove has an appropriate value (lead B), and the solid line L3 indicates a value (lead) of the lead of the thread groove deviating from the appropriate value. The state of the thread groove when A) is shown.

  An object of the present invention is to provide a thread rolling device that can suppress a decrease in accuracy of a thread groove formed by a plurality of rolling dies.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
A thread rolling device that solves the above problems is supported by a holding part having a through-hole into which a rod-shaped workpiece is inserted, and a shaft that is rotatable about an axis parallel to the axis of the work held by the holding part. And a plurality of rolling dies arranged at equal intervals in the circumferential direction around the axis of the workpiece. The apparatus rotates a plurality of rolling dies and plastically processes a thread groove in the workpiece by sandwiching the workpiece in the radial direction while relatively moving in the axial direction with respect to the workpiece. In addition, the apparatus includes a plurality of rollers that support the work by contacting the outer peripheral surface of the work held by the holding unit. These rollers are arranged at equal intervals in the circumferential direction around the axis of the workpiece held by the holding unit.

  According to the above configuration, when a thread groove is formed on the outer peripheral surface of the workpiece by a plurality of rolling dies, even if a large load is applied in a direction perpendicular to the axis of the workpiece, the large load is applied to the outer peripheral surface of the workpiece. It can be received with the roller in contact. Therefore, even if a large load is applied to the workpiece as described above, the workpiece can be prevented from tilting along with it, and the thread groove is formed while the workpiece is tilted, and the accuracy of the screw groove is reduced. Can be suppressed.

  The roller is preferably provided on the outer peripheral surface of the rolling die, and the axis of the roller and the axis of the rolling die are preferably located on the same axis. In this case, since the axis of the roller is not inclined with respect to the axis of the rolling die, it is possible to prevent the workpiece supported by the roller from being inclined with the inclination.

  The screw rolling device is provided with a crest that plastically processes the thread groove by contacting the outer peripheral surface of the workpiece on the outer peripheral surface of the rolling die. The rolling dies may be arranged so as to be shifted from each other in the axial direction so that the position is shifted for each rolling die. In this case, it is preferable that the roller is provided adjacent to the holding portion side of the peak portion closest to the holding portion in the rolling die.

  According to this configuration, when a large load acts on the workpiece in a direction perpendicular to the axis from the peak portion that is first pressed against the outer peripheral surface of the workpiece to form a thread groove, the large load is applied to the peak. It becomes easy to receive with the roller provided in the rolling die different from the rolling die provided with the portion. And by receiving the said heavy load with the roller, the inclination of the workpiece | work accompanying the effect | action of the heavy load can be suppressed more reliably.

  The plurality of rolling dies are a pair of rolling dies, and the rollers are preferably provided on the outer peripheral surfaces of the pair of rolling dies. In this case, the number of rolling dies and rollers can be minimized to simplify the configuration of the rolling device.

  The diameter of the roller is smaller than the crest of the rolling die, and when the chamfer of the rolling die abuts against the work, when the plastic processing of the screw groove is started, the roller The value is in contact with the surface.

Schematic which shows the structure of a rolling apparatus. Schematic which shows the formation process of the screw groove by the apparatus. Schematic which shows the formation process of the screw groove by the apparatus. Schematic which shows the prior art example of a rolling apparatus. Schematic which shows the formation process of the screw groove by the apparatus. Schematic which shows the formation process of the screw groove by the apparatus.

Hereinafter, an embodiment of a thread rolling device will be described with reference to FIGS.
The rolling apparatus shown in FIG. 1 includes a work holding mechanism for holding a bar-shaped work 11. The work holding mechanism is provided with a holding collar 12 having a through hole 12a into which the work 11 is inserted. Note that the inner diameter of the through hole 12 a in the holding collar 12 is slightly larger than the outer diameter of the work 11. The work holding mechanism supports the work 11 inserted into the through hole 12 a of the holding collar 12 while regulating the tilt by the holding collar 12. Furthermore, the workpiece holding mechanism can move the workpiece 11 supported by the holding collar 12 in the direction in which the axis (the one-dot chain line L1 in FIG. 1) extends or rotate around the axis. ing.

  The rolling device includes a plurality of rolling dies 13 (in this example, a pair of rolling dies 13) that are arranged at equal intervals in the circumferential direction around the axis of the work 11 held by the holding collar 12 (dashed line L1). A rolling die 13) is provided. These rolling dies 13 are the same product having the same shape, and are rolled so as to be rotatable about an axis parallel to the axis of the work 11 held by the holding collar 12 (dashed line L4). Supported on a manufacturing device. Therefore, the axis of the workpiece 11 (dashed line L1) and the axis of the rolling die 13 (dashed line L4) are parallel to each other. Furthermore, the axis of each rolling die 13 is located at equal intervals in the circumferential direction centered on the axis of the workpiece 11. Further, on the outer peripheral surface of the rolling die 13, a plurality of annular ridges 14 for forming screw grooves on the outer peripheral surface of the work 11 (screw blank) are spaced apart in the axial direction of the work 11. Are fixed in a line.

  1, 2, and 3 show the movement of the workpiece 11 when forming the thread groove of the ball screw by the rolling device. The apparatus rotates the plurality of rolling dies 13 and moves the work 11 held by the holding collar 12 toward the rolling dies 13 (the right side in FIG. 1) while moving the work with the plurality of rolling dies 13. By inserting 11 in the radial direction, a thread groove is plastically processed on the outer peripheral surface of the workpiece 11. Specifically, as shown in FIGS. 2 and 3, the work 11 moves to the right side in the figure while rotating between the rolling dies 13. As a result, the ridges 14 provided on one rolling die 13 and the ridges 14 provided on the other rolling die 13 are alternately placed on the left side in the drawing in order from the workpiece 11. The outer circumferential surface of the workpiece 11 is pressed against the outer circumferential surface of the workpiece 11, and a thread groove is formed on the outer circumferential surface of the work 11.

  The positions of the plurality of rolling dies 13 in the axial direction are preliminarily set at positions where the pitches of the thread grooves formed by the ridges 14 of the rolling dies 13 are shifted in the axial direction of the workpiece 11 so that no so-called pitch deviation occurs. It has been adjusted. As a result, the positions of the rolling dies 13 in the axial direction are shifted from each other, and the positions of the ridges 14 in the axial direction differ (shift) for each rolling die 13.

Next, a support structure for the work 11 when a thread groove is formed on the outer peripheral surface of the work 11 by the rolling device will be described.
The rolling device includes a plurality of rollers 15 that support the workpiece 11 by contacting the outer circumferential surface of the workpiece 11 when forming a thread groove on the outer circumferential surface of the workpiece 11 held by the holding collar 12. The roller 15 is provided on the outer peripheral surface of the rolling die 13 next to the peak portion 14 closest to the holding collar 12 on the holding collar 12 side. Accordingly, the rollers 15 are arranged at equal intervals in the circumferential direction around the axis of the workpiece 11 held by the holding collar 12 (the one-dot chain line L1 in FIG. 1). Further, the axis of the roller 15 and the axis of the rolling die 13 are located on the same axis (the one-dot chain line L4 in FIG. 1), and the circumferential direction around the axis (the one-dot chain line L1) of the workpiece 11 Are located at regular intervals. The diameter of the roller 15 is smaller than that of the crest 14, and the chamfer 14 is brought into contact with the outer peripheral surface so as to form a screw groove on the outer peripheral surface of the work 11. When the roller 15 is in a state where the roller 15 is in contact with the outer peripheral surface of the work 11, the value is set.

Next, the operation of the rolling device will be described.
In this rolling apparatus, the workpiece 11 held by the holding collar 12 is sandwiched between the rolling dies 13, so that the crest 14 of the rolling die 13 is pressed against the outer peripheral surface of the workpiece 11. As the rolling die 13 rotates under this state, the work 11 moves in the axial direction while rotating, and a thread groove is formed on the outer peripheral surface of the work 11 by the ridges 14. The state of the thread groove formed at this time is shown by a solid line L2 in FIG.

  Incidentally, when forming the thread groove, the peak portion 14 that is first pressed against the outer peripheral surface of the workpiece 11 is the peak portion 14 closest to the holding collar 12 in the lower rolling die 13 in FIGS. When only the peak portion 14 is pressed against the outer peripheral surface of the workpiece 11, a plurality of rollers 15 are in contact with the outer peripheral surface of the workpiece 11, and the workpiece 11 is supported by the rollers 15 and the holding collar 12. . And the peak part 14 pressed against the outer peripheral surface of the workpiece 11 next is the peak part 14 closest to the holding collar 12 in the upper rolling die 13 in FIGS.

  Between the time when the peak portion 14 is first pressed against the outer peripheral surface of the work 11 and the time when the next peak portion 14 is pressed, the axis line of the workpiece 11 is determined only from the peak portion 14 pressed against the work 11 first. A heavy load acts in the orthogonal direction. However, since such a heavy load can be received by the roller 15 that contacts the outer peripheral surface of the work 11, it is possible to suppress the work 11 from being inclined with the action of the large load. For this reason, it can suppress that the thread groove is formed by the peak portion 14 while the workpiece 11 is inclined and the accuracy of the thread groove is lowered.

According to the embodiment described in detail above, the following effects can be obtained.
(1) When forming a thread groove of a ball screw with a plurality of rolling dies 13 in a rolling device, it can control that the accuracy of the thread groove falls.

  (2) The roller 15 in contact with the outer peripheral surface of the work 11 is provided on the outer peripheral surface of the rolling die 13 and is positioned on the same axis as the rolling die 13. For this reason, the axis of the roller 15 is not inclined with respect to the rolling die 13, and it is possible to suppress the inclination of the workpiece 11 supported by the roller 15 with the inclination.

  (3) The roller 15 is provided next to the holding collar 12 side of the peak portion 14 closest to the holding collar 12 in the rolling die 13. In this case, when a large load is applied to the workpiece 11 in a direction perpendicular to the axis from the peak portion 14 that is first pressed against the outer peripheral surface of the workpiece 11 in order to form a thread groove, the large load is applied to the peak. It becomes easy to receive with the roller 15 provided in the rolling die 13 different from the rolling die 13 provided with the portion 14. And by receiving the said heavy load with the roller 15, the inclination of the workpiece | work 11 accompanying the effect | action of the heavy load can be suppressed more reliably.

  (4) The rolling device forms a thread groove with a pair of rolling dies 13, and each of the rolling dies 13 is provided with a roller 15. For this reason, the number of rolling dies 13 and rollers 15 can be minimized, and the configuration of the rolling device can be simplified.

In addition, the said embodiment can also be changed as follows, for example.
The roller 15 is not necessarily provided adjacent to the peak portion 14 on the outer peripheral surface of the rolling die 13, and may be provided away from the peak portion 14 closer to the holding collar 12 than the peak portion 14.

The roller 15 may be provided separately from the rolling die 13. In this case, the axis of the roller 15 is preferably provided on the same axis as the axis of the rolling die 13.
The pair of rolling dies 13 provided in the rolling device is not necessarily a pair, and three or more rolling dies 13 may be provided.

  In the rolling device, when rolling the thread groove on the outer peripheral surface of the workpiece 11, the workpiece 11 and the rolling die 13 are moved to the same shape by bringing the rolling die 13 closer to the workpiece 11 held by the holding collar 12. 11 may be relatively moved in the axial direction. In addition, the workpiece 11 and the rolling die 13 can be relatively moved in the axial direction of the workpiece 11 by bringing the workpiece 11 and the rolling die 13 closer to each other.

  DESCRIPTION OF SYMBOLS 11 ... Work, 12 ... Holding collar (holding part), 12a ... Through-hole, 13 ... Rolling die, 14 ... Mountain part, 15 ... Roller.

Claims (5)

A holding portion having a through hole into which a rod-shaped workpiece is inserted; and
A plurality of components that are rotatably supported around an axis parallel to the axis of the workpiece held by the holding unit, and are arranged at equal intervals in a circumferential direction around the axis of the workpiece. A rolling die,
While rotating the rolling die, and relative movement in the axial direction with respect to the workpiece, while rolling the workpiece in the radial direction, the screw rolling device for plastic working the thread groove in the workpiece,
A plurality of rollers that are arranged at equal intervals in a circumferential direction around the axis of the workpiece held by the holding portion and that support the workpiece by contacting the outer circumferential surface of the workpiece; A featured screw rolling device.   The thread rolling device according to claim 1, wherein the roller is provided on an outer peripheral surface of the rolling die, and an axis of the roller and an axis of the rolling die are located on the same axis. The outer peripheral surface of the rolling die is provided with a ridge for plastic working the thread groove by contacting the outer peripheral surface of the workpiece,
The rolling dies are arranged so as to be shifted from each other in the axial direction so that the position of the peak portion in the axial direction of the rolling dies is shifted for each rolling die,
3. The thread rolling device according to claim 2, wherein the roller is provided adjacent to the holding portion side of the peak portion closest to the holding portion in the rolling die.   The thread rolling device according to claim 2 or 3, wherein the plurality of rolling dies are a pair of rolling dies, and the rollers are respectively provided on the outer peripheral surfaces of the pair of rolling dies.   The diameter of the roller is smaller than the crest portion of the rolling die, and when the chamfer portion of the rolling die abuts against the workpiece, plastic deformation of the thread groove is started, The thread rolling device according to any one of claims 2 to 4, wherein the screw rolling value is a value that abuts on the outer peripheral surface of the workpiece.

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