JP5425562B2 - Rolling element screw device - Google Patents

Description

  The present invention relates to a rolling element screw device.

  Conventionally, a rolling element rolling groove formed spirally on the outer periphery of the screw shaft and a load rolling element rolling groove facing the rolling element rolling groove on the inner periphery of the through hole of the moving member through which the screw shaft passes are provided. A plurality of rolling elements are formed by interposing a plurality of rolling elements in a rolling element rolling path formed by the rolling element rolling grooves and the loaded rolling element rolling grooves, and communicating with both ends of the rolling element rolling path by circulating parts. There are known rolling element screw devices and linear actuators that circulate infinitely. Various methods are known for attaching this circulating component.

  The plate-like fixing member described in Patent Document 1 includes a main body pressing portion that covers the circulating component main body, and an extending contact portion that should be in contact with the extending portion continuously from the main body pressing portion. Prior to fastening by a member, the circulating part is divided into two parts by having a structure in which the connecting part between the main body pressing part and the extended contact part forms an acute angle on the side opposite to the side in contact with the circulating part. In such a rolling element screw device, regardless of the material of the circulating part, the joining of the circulating part is enhanced even when used under conditions of high load and large thrust.

Utility Model Registration No. 3097525

  However, according to the conventional structure, since only the substantially central portion in the longitudinal direction of the circulating part is pressed, there is a possibility that the joint of the two-part circulating part may be opened at a place where the circulating part is not covered. It was. In particular, when the rolling elements circulate in the circulating parts, when the rolling elements that have rolled on the rolling element rolling path are introduced into the circulating parts, the linear parts of the substantially U-shaped circulating parts and both ends of the linear parts are suspended. Since stress is concentrated most at the intersection (corner part) with a pair of leg parts, there is a problem that it is difficult to suppress the opening of the circulating parts in the corner part.

  In addition, as a method of suppressing the opening of the corner portion, a structure that completely covers the entire circulating component is known, but according to this method, it is necessary to manufacture a fixing member in accordance with the length of the circulating component. As a result, the fixing member cannot be shared, and it is difficult to reduce the manufacturing cost.

  The present invention has been made to solve the above-described problems, and can suppress the opening of the corner portion of the circulating component, and can fix the fixing member regardless of the length of the circulating component to be used. An object of the present invention is to provide a rolling element screw device using a fixing member that can be shared.

The rolling element screw device according to the present invention that solves the above-described problems includes a screw shaft having a spiral rolling element rolling groove formed on the outer periphery thereof, a through hole through which the screw shaft passes in the longitudinal direction, and the through hole. A moving member in which a spiral loaded rolling element rolling groove is formed on the inner peripheral surface of the rolling element rolling groove together with the rolling element rolling groove, a central straight portion, and a drooping from both ends of the central straight portion A circulating part in which an unloaded rolling element rolling path is formed which communicates both ends of the loaded rolling element rolling path and forms an infinite circulation of the rolling element together with the loaded rolling element rolling path. A fixing member for fixing the circulating component to the moving member, and a plurality of rolling elements arranged and accommodated in the infinite circulation path and circulated with relative rotation of the screw shaft and the moving member are provided, and the circulation Parts along the center of the unloaded rolling element rolling path A pair of circulating component bodies divided into two, and the fixing member extends in the longitudinal direction of the circulating component and has a substantially semi-cylindrical pressing portion having an opening along the longitudinal direction; and a fastening flange from the open end of the opening extending along the moving member, the inner peripheral portion of the pressing portion, viewed including the abutment and respectively abuts the circulating member body by at least one point, the pressing In a cross section perpendicular to the longitudinal direction of the part, a horizontal line parallel to the fastening flange and a vertical line perpendicular to the horizontal line intersect with each other at the central axis of the semi-cylindrical shape, and these four quadrants are divided in the longitudinal direction. When the first quadrant to the fourth quadrant are rotated counterclockwise from the upper right in a cross section perpendicular to the first quadrant, the abutment portion is formed at least one place in the first quadrant and the second quadrant, and the first quadrant abuts. And A gap is formed in the inner peripheral portion of the pressing portion when attached to the moving member between the contact portion of the second quadrant, and the fixing member includes the central straight portion and the leg portion. It is characterized by covering a corner portion where and intersect .

  As described above, according to the present invention, the inner peripheral portion of the pressing portion is in contact with the circulating component by the contact portions that are in contact with the circulating component body. In addition to fixing the circulating component, it is possible to prevent the circulating component from opening in the horizontal direction.

The perspective view for demonstrating the outline of the linear actuator which concerns on the 1st Embodiment of this invention. Sectional drawing for demonstrating the structure of the linear actuator which concerns on the 1st Embodiment of this invention. The perspective view of the circulation component used for the linear actuator which concerns on the 1st Embodiment of this invention. The perspective view for demonstrating the attachment state of the member for fixing. The side view for demonstrating the attachment state of the member for fixing. The front view for demonstrating the attachment state of the member for fixing. The perspective view for demonstrating the outline of the rolling element screw apparatus which concerns on the 2nd Embodiment of this invention.

  Hereinafter, a rolling element screw device using a fixing member according to the present invention will be described with reference to the drawings. The following embodiments do not limit the invention according to each claim, and all combinations of features described in the embodiments are not necessarily essential to the solution means of the invention. .

[First Embodiment]
FIG. 1 is a perspective view for explaining the outline of the linear actuator according to the first embodiment, and FIG. 2 is a cross-sectional view for explaining the structure of the linear actuator according to the first embodiment. FIG. 3 is a perspective view of a circulating component used in the linear actuator according to the first embodiment, FIG. 4 is a perspective view for explaining a mounting state of a fixing member, and FIG. It is a side view for demonstrating the attachment state of a member, and FIG. 6 is a front view for demonstrating the attachment state of the member for fixing. In the following description, in FIG. 6, the illustrated x direction is defined as the horizontal direction and the y direction is defined as the vertical direction.

  As shown in FIG. 1 and FIG. 2, the linear actuator 1 has a substantially U-shaped raceway member 10 having inner wall surfaces 11, 11 facing each other, and the raceway member 10 is sandwiched between the inner wall surfaces 11, 11. And a guide member that cooperates with the inner wall surfaces 11 and 11 on both side surfaces, and a ball screw portion that cooperates with a screw shaft 30 inserted through a through hole 21 formed in the center. 20. The linear actuator 1 configured as described above reciprocates along the track member 10 by rotating the end of the screw shaft 30 in the circumferential direction by assembling the end of the screw shaft 30 to the drive source 16 such as an electric motor. Can be made. Further, such a linear actuator 1 has an integral structure of the guide portion and the ball screw portion, and thus has a highly rigid and highly accurate actuator function in a minimum space.

  Next, the guide part of the linear actuator 1 which concerns on this embodiment is demonstrated. The track member 10 has inner wall surfaces 11 and 11 that face each other, and two rolling grooves 13 and 13 are formed on the inner wall surfaces 11 and 11 along the longitudinal direction. Further, at both ends in the longitudinal direction of the track member 10, housings 14 and 15 for holding the screw shaft 30 rotatably are provided. The housings 14 and 15 are coupled to the track member 10 by fastening means such as bolts. In addition, a drive source 16 such as an electric motor is attached to one housing 15, and an output shaft of the drive source 16 and a screw shaft are connected by an appropriate joint or the like.

  The moving member 20 includes a block body 24 and a pair of lid bodies 23 and 23 that are assembled to both ends of the block body 24 in the longitudinal direction. The lid body 23 is formed with a direction changing path on the surface facing the block body 24. Two load rolling grooves 26, 26 facing the rolling grooves of the inner wall surfaces 11, 11 are formed on both side surfaces of the block body 24, respectively. Further, a return passage (not shown) corresponding to the load rolling groove 26 is formed between the through hole of the block body 24 and the inner wall surfaces 11 and 11 as a through hole.

  The cross-sectional shapes of the rolling grooves 13 and 13 and the load rolling grooves 26 and 26 are formed, for example, in a so-called circular arc shape having a curvature slightly larger than the radius of the linear guide portion ball 12 described later. Yes.

  In addition, a plurality of rolling elements are interposed as linear guide part balls 12 between the track member 10 and the moving member 20, and the linear guide part balls 12 include a rolling groove 13 and a load rolling groove. , And an infinite circulation path constituted by a direction change path connecting the rolling path and the return path. Further, a retainer having a curvature corresponding to the radius of the linear guide portion ball 12 is interposed between the linear guide portion balls 12, and the retainer is connected by a belt-like member.

  Next, a ball screw portion having a function as the most characteristic rolling element screw device in the present embodiment will be described. As shown in FIG. 1 and FIG. 2, a through hole 21 is formed in the longitudinal direction of the screw shaft 30 at a substantially central portion of the moving member 20, and the screw shaft 30 passes through the through hole 21. A spiral rolling element rolling groove 31 is formed on the outer peripheral surface of the screw shaft 30. A load rolling element rolling groove 27 corresponding to the rolling element rolling groove 31 is also formed on the inner wall surface of the through hole 21. A load rolling element rolling path is formed between the rolling element rolling groove 31 and the load rolling element rolling groove 27. A plurality of rolling elements are interposed as screw shaft balls 22 in the load rolling element rolling path. A spacer having a curvature corresponding to the radius of the screw shaft ball 22 is interposed between the screw shaft balls 22.

  The cross-sectional shapes of the rolling element rolling groove 31 and the loaded rolling element rolling groove 27 are formed in a so-called Gothic arch shape, for example, composed of two arcs having a curvature slightly larger than the radius of the screw shaft ball 22.

  Further, a preload is applied between the rolling element rolling groove 31 and the load rolling element rolling groove 27. As a method of applying the preload, for example, than a gap between the screw shaft 30 and the block body 24. A so-called oversize system in which an oversized ball having a slightly larger diameter is used as the screw shaft ball 22 and is filled with these balls can be employed.

  The moving member 20 is provided with a circulation component 50 for circulating the screw shaft ball 22 reaching one end of the load rolling element rolling path to the other end of the load rolling element rolling path. The circulating component 50 forms a ball return path for the screw shaft as an unloaded rolling element rolling path that communicates one end and the other end of the loaded rolling element rolling path, thereby realizing infinite circulation of the screw shaft ball 22. Yes.

  The circulating component 50 is assembled to the moving member 20 and is fixed by a fixing member 40 attached to a fixing member attaching portion 25 formed on the moving member 20. As shown in FIG. 3, the U-shaped circulation component 50 includes a central straight portion 51 extending in the longitudinal direction and a pair of legs 52 depending from both ends of the central straight portion 51 so as to penetrate the inside. A ball return passage for a screw shaft is formed in the shaft. The circulating component 50 is made of synthetic resin, and is configured by combining a pair of circulating component bodies 50a and 50a formed in the same shape and fastening them with welding or bolts. As described above, the circulating component 50 includes the circulating component bodies 50a and 50a that are divided into two along the center of the no-load rolling element rolling path. Furthermore, a scooping-up portion 53 that scoops up the screw shaft ball 22 that rolls on the loaded rolling element rolling path is formed at the tip of the leg portion 52.

  Next, with reference to FIGS. 4-6, the fixing member 40 which attaches the circulation component 50 is demonstrated. As shown in FIG. 4, the fixing member 40 is formed of, for example, a thin metal plate, extends along the longitudinal direction of the central straight portion 51 of the circulation component 50, and has an opening 41 a along the longitudinal direction. A pressing part 41 having a substantially semi-cylindrical cross section, and fastening flanges 42, 42 extending from the end of the opening 41 a along the mounting surface of the moving member 20. Further, the fastening flanges 42 and 42 are respectively provided with fastening holes 43, and fastening bolts are inserted into the fastening holes 43 to fix the fixing member 40 together with the circulating component 50 to the moving member 20.

  As shown in FIG. 5, the length l in the longitudinal direction of the pressing portion 41 is formed to be equal to the length of the central straight portion 51 of the circulating component 50. The length l is only required to cover the corner portion 54 where the central straight portion 51 and the leg portion 52 of the circulation component 50 intersect with the fixing member 40. The length l is formed longer than the central straight portion 51. It doesn't matter.

  As shown in FIG. 6, the pressing portion 41 is formed in a semicircular cylindrical shape in a cross section orthogonal to the longitudinal direction, and the contact portion 44 of the inner peripheral portion of the pressing portion 41 contacts the circulating component 50. Thus, the circulating component 50 is fixed. The contact portion 44 virtually imagines a horizontal line x parallel to the extending direction of the fastening flange 42 and a vertical line y orthogonal to the horizontal line x at a semicircular center point O. The horizontal line x and the vertical line y The four quadrants are divided into the first quadrant, the second quadrant, the third quadrant, and the fourth quadrant counterclockwise from the upper right (horizontal right side and vertical upper side). At least one place is formed in the second quadrant. That is, the contact portions 44 and 44 are in contact with the pair of circulating component bodies 50a and 50a, respectively, and a gap 45 is formed between the contact portions 44 and 44 along the inner peripheral portion of the pressing portion 41. ing.

  The abutting portions 44, 44 can be formed in the range of 45 ° ± 25 °, that is, in the range of 20 to 70 °, with respect to the horizontal direction. When the angle formed with the horizontal component is 20 ° or less, the vertical component force Fy is reduced to about 1/3 of the horizontal component force Fx, and thus the force for fixing the circulating component 50 in the vertical direction becomes weak. There is a possibility that the circulating component 50 is detached in the vertical direction with the momentum when the ball 22 for the screw shaft enters the circulating component 50. Further, when the angle formed by the horizontal component is 70 ° or more, the horizontal component force Fx is reduced to about ３ of the vertical component force Fy, so that the force for fixing the circulating component 50 in the horizontal direction is increased. Since it becomes weak, the circulating component 50 may be divided into two parts. Therefore, if the contact portions 44 are formed in this range, the horizontal component Fx and the vertical component Fy can be set with good balance. In addition, in order to distribute a component force equally to the horizontal direction Fx and the vertical direction Fy, it is suitable to form in the position of 45 degrees. Further, in order to equally apply the horizontal components Fx and Fy in the abutting portions 44 and 44 formed in the first quadrant and the second quadrant, it is preferable to form them at positions symmetrical with respect to the vertical line y.

  Since the abutment portion 44 is formed in the first quadrant and the second quadrant so as to abut against the circulation component main bodies 50 a and 50 a, the fastening force of the fixing member 40 is applied to the circulation component 50. And have a component of vertical component Fy and horizontal component Fx. As described above, since the fastening force has the vertical component Fy and the horizontal component Fx, the vertical component Fy is applied in a direction in which the circulating component 50 is fixed to the moving member 20, and the horizontal component Fx It is given in a direction to suppress the expansion of the circulating component main bodies 50a, 50a to be configured. Therefore, the fixing member 40 used in the ball screw portion of the linear actuator 1 according to the present embodiment can securely attach and fix the circulating component 50 to the moving member 20 and also the circulating component main body constituting the circulating component 50. Expansion of 50a and 50a can also be prevented.

  Further, the fixing member 40 is formed such that the length l of the holding portion 41 in the longitudinal direction is longer than the length of the central straight portion 51 of the circulating component 50 so that the corner portion 54 of the circulating component 50 can be covered. Therefore, after rolling up the screw shaft ball 22, it rolls in the leg portion 52, and when the screw shaft ball 22 changes the traveling direction in the corner portion 54 to the extending direction of the central straight portion 51. In addition, it is possible to prevent the circulation component main bodies 50a and 50a from expanding at the corner portion 54 that collides with the inner wall of the screw shaft ball return passage and is subjected to the greatest force by the collision.

  Moreover, since the length l of the holding | suppressing part 41 should just be formed more than the length of the center linear part 51, among the variations of the linear actuator 1 manufactured, it is the circulation part which has the longest center linear part 51. If the fixing member 40 is formed together, a fixing member capable of covering the corner portion can be obtained even if the fixing member 40 is applied to the remaining circulating parts, and the linear manufactured. In the variation of the actuator, the fixing member 40 can be shared regardless of the length of the circulating component, which can contribute to cost reduction.

  Further, since the gap 45 is formed between the contact portions 44, 44, the fastening force of the fixing member 40 can be concentrated and applied to the circulating component 50. The fastening force can be applied in a direction in which the circulating component 50 is efficiently fixed and in a direction in which the circulating component main bodies 50a and 50a are prevented from expanding.

[Second Embodiment]
The case where the fixing member 40 is applied to the ball screw portion of the linear actuator 1 according to the first embodiment has been described above. In the second embodiment to be described next, an example in which the fixing member 40 is applied to the rolling element screw device 2 will be described. Note that members that are the same as or similar to those in the first embodiment described above are given the same reference numerals, and descriptions thereof are omitted.

  FIG. 7 is a perspective view for explaining the outline of the rolling element screw device according to the second embodiment.

  As shown in FIG. 7, the rolling element screw device 2 according to the present embodiment includes a screw shaft 130 having a spiral rolling element rolling groove 131 formed on the outer periphery, and a through hole 121 through which the screw shaft 130 passes. And a moving member 120 formed with a load rolling element rolling groove (not shown) facing the rolling element rolling groove 131 on the inner peripheral surface of the through-hole 121, the screw shaft 130, the moving member 120, and the like. A plurality of rolling elements (not shown) that roll on a loaded rolling element rolling path constituted by the rolling element rolling grooves 131 and the loaded rolling element rolling grooves are interposed between the moving members 120. Are assembled so as to be able to move smoothly in the axial direction of the screw shaft 130.

  Further, the moving member 120 is provided with a circulation component 50 that circulates the rolling element that has reached one end of the load rolling element rolling path to the other end of the load rolling element rolling path by the movement of the moving member 120 in the axial direction. Yes. The circulating component 50 forms a rolling element return passage that communicates one end and the other end of the load rolling element rolling path, thereby realizing infinite circulation of the rolling element.

  As shown in FIG. 7, the circulating component 50 is fixed to the moving member 120 by a fixing member 40. Since the shape and mounting method of the circulating component 50 and the fixing member 40 are the same as those of the circulating component 50 and the fixing member 40 described in the first embodiment, detailed description thereof is omitted.

  As described above, in the linear actuator according to the first embodiment and the fixing member 40 used in the rolling element screw device according to the second embodiment, the contact portions 44 and 44 are positioned symmetrically with respect to the vertical line y. Although the case where it formed in this way was demonstrated, the position of the contact parts 44 and 44 can be changed suitably in consideration of the position where the fixing member 40 is attached, the state where the rolling element rolls, or the like.

  Moreover, although the case where the contact part 44 is formed at a position where the angle formed with the horizontal direction is 30 to 60 ° has been described, when the expansion of the circulating component 50 is further suppressed, the angle formed with the horizontal direction is determined. When the circulating component 50 needs to be fixed more firmly, the angle formed with the horizontal direction may be increased.

  Furthermore, in the said embodiment, although the case where the ball | bowl was applied as a some rolling element was demonstrated, a cylindrical roller may be applied to a rolling element. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  The fixing member according to the present invention can suppress the opening of the corner portion of the circulating component, and can share the fixing member regardless of the length of the circulating component used.

  DESCRIPTION OF SYMBOLS 1 Linear actuator, 20, 120 Moving member, 21, 121 Through-hole, 22 Ball for screw shaft, 26 Load rolling groove, 27 Load rolling element rolling groove, 30, 130 Screw shaft, 31, 131 Rolling element rolling groove , 40 fixing member, 41 holding part, 41a opening, 42 fastening flange, 44 abutting part, 45 gap, 50 circulating part, 50a circulating part body, l holding part length, x horizontal line, y vertical line.

Claims (2)

A screw shaft having a spiral rolling element rolling groove formed on the outer periphery;
The screw shaft has a through hole penetrating in the longitudinal direction, and a spiral load rolling element rolling groove is formed on the inner peripheral surface of the through hole together with the rolling element rolling groove. A moving member;
A center straight portion and a pair of legs hanging from both ends of the center straight portion, and the ends of the load rolling element rolling path are communicated to form an endless circulation of the rolling elements together with the loaded rolling element rolling path. A circulating part in which a loaded rolling element rolling path is formed;
A fixing member for fixing the circulating component to the moving member;
A plurality of rolling elements arranged and accommodated in the endless circulation path and circulated with relative rotation of the screw shaft and the moving member;
The circulating component has a pair of circulating component bodies divided into two along the center of the unloaded rolling element rolling path,
The fixing member extends in the longitudinal direction of the circulating component, and has a substantially semi-cylindrical pressing portion having an opening along the longitudinal direction;
A fastening flange extending along the moving member from the opening end of the opening,
An inner peripheral portion of the pressing portion, viewed including the abutment and respectively abuts the circulating member body by at least one place,
In a cross section perpendicular to the longitudinal direction of the pressing portion, a horizontal line parallel to the fastening flange and a vertical line perpendicular to the horizontal line intersect at the center axis of the semi-cylindrical shape, and are divided into four quadrants. When the first quadrant to the fourth quadrant are rotated counterclockwise from the upper right in a cross section perpendicular to the longitudinal direction, the contact portion is formed at least one place in the first quadrant and the second quadrant,
Between the contact portion of the first quadrant and the contact portion of the second quadrant, when attached to the moving member, a gap is formed in the inner peripheral portion of the pressing portion,
The rolling element screw device according to claim 1, wherein the fixing member covers a corner portion where the central straight portion and the leg portion intersect . The longitudinal length of the retainer portion, the rolling body screw device according to claim 1, characterized in that it is formed over the length of the longitudinal direction of the circulating member.

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