JP2010025129A - Ball screw - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ball screw capable of correctly aligning balls moving from a noload return passage of a circulation member to a load ball rolling groove of a nut. <P>SOLUTION: A section area shape of the load ball rolling groove 2a of the nut 2 is formed as a Gothic arch groove form including two circular curves having curvature radius longer than a radii of the balls 3. A section area shape of a part of the nut 2 connected to the load ball rolling groove 2a at an end part of the noload return passage 14 of the circulation member 8 in a longitudinal direction is formed as the Gothic circular curve in accordance with the section area shape of the load ball rolling groove 2a of the nut 2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a ball screw in which a plurality of balls are interposed between a spiral ball rolling groove on an outer peripheral surface of a screw shaft and a spiral load ball rolling groove on an inner peripheral surface of a nut so as to allow rolling motion. About.

  A ball screw is a mechanical element that converts the rotational motion of a screw shaft into linear motion of a nut. In order to reduce the friction when rotating the screw shaft relative to the nut, between the ball rolling groove on the outer peripheral surface of the screw shaft and the loaded ball rolling groove on the inner peripheral surface of the nut facing this A plurality of balls are interposed so as to allow rolling motion.

  In order to circulate the ball that rolls between the screw shaft and the nut, a return pipe (circulation member) is attached to the nut. The return pipe is formed with a no-load return path that connects one end and the other end of the spiral loaded ball rolling groove of the nut. The ball that rolls between the screw shaft and the nut rolls up to one end of the loaded ball rolling groove of the nut, and is then rolled up into the unloaded return path of the return pipe. After passing through the no-load return path, the ball is returned to the other end of the nut loaded ball rolling groove.

  The return pipe is manufactured, for example, by bending a metal pipe. The cross-sectional shape of the unloaded return path of the return pipe is formed into a circular shape (see Patent Document 1). The radius of the circular unloaded return path is slightly larger than the radius of the ball and there is play around the ball. As described above, both ends of the return pipe in the length direction are bent by a bending machine. In consideration of deformation of the unloaded return path when bent, the size of the play around the ball, that is, the inner diameter of the unloaded return path is determined.

Both ends in the length direction of the bent return pipe are connected to one end and the other end of the load ball rolling groove of the nut. The loaded ball rolling groove of the nut is formed in a Gothic arch groove shape composed of two arcs having a radius larger than the radius of the ball. This is because the loaded ball rolling groove of the nut and the ball are brought into contact at two points.
JP 2008-111466 A

  In order to smoothly circulate the balls, it is necessary to suppress the meandering of the balls moving from the unloaded return path of the return pipe to the loaded ball rolling groove of the nut and to align them correctly. When the ball shifts from the unloaded return path of the return pipe to the loaded ball rolling groove of the nut, when the ball meanders, the ball collides with the edge of the loaded ball rolling groove of the nut. For this reason, there exists a possibility of generating a noise or causing the early breakage | damage of a ball | bowl.

  However, the cross-sectional shape of the unloaded return path of the return pipe is formed in a circular shape having a radius slightly larger than the radius of the ball. On the other hand, the cross-sectional shape of the loaded ball rolling groove of the nut is formed in a Gothic arch groove shape that contacts the ball at two points. For this reason, a step is likely to occur at the joint between the unloaded return path of the return pipe and the loaded ball rolling groove of the nut, and the meandered ball in the return pipe easily collides with the end of the loaded ball rolling groove of the nut. . Even if the load ball rolling groove of the nut is chamfered so that there is no step at the joint between the end of the return pipe and the load ball rolling groove of the nut, The meandering of the ball does not heal, and play of the ball at the chamfered portion of the nut loaded ball rolling groove becomes a problem.

  Then, an object of this invention is to provide the ball screw which can align correctly the ball | bowl which transfers to the loaded ball rolling path of a nut from the unloaded return path of a circulation member.

  The present invention will be described below.

  In order to solve the above-mentioned problem, the invention according to claim 1 is directed to a screw shaft having a spiral ball rolling groove on an outer peripheral surface, opposite to the ball rolling groove of the screw shaft, and more than the radius of the ball. A nut having a spiral loaded ball rolling groove having a cross-sectional shape in the shape of a Gothic arch groove including two arc-shaped curves having a large radius of curvature, and one end and the other end of the load ball rolling groove of the nut And a circulating member having a closed curved cross-sectional shape surrounding the ball, and a plurality of balls arranged in the loaded ball rolling groove of the nut and the unloaded return path A cross-sectional shape of a portion of the circulating member connected to the load ball rolling groove at a lengthwise end of the no-load return path of the circulation member is a cross section of the load ball rolling groove of the nut. Gothic arch groove shape to match the shape A ball screw to be made.

  According to a second aspect of the present invention, in the ball screw according to the first aspect, the cross-sectional shape of the screw shaft side portion of the end portion of the circulation member in the length direction of the no-load return path is Formed in a Gothic arch groove shape including two arc-shaped curves having a radius of curvature larger than the radius, and the cross-sectional shape of the end portion in the length direction of the unloaded return path of the circulation member is larger than the radius of the ball It includes a total of four arc-shaped curves with a radius.

  The invention according to claim 3 is the ball screw according to claim 2, and includes two arc-shaped curves on the nut side in a cross section of the end portion of the circulation member in the length direction of the no-load return path. The amount of movement of the ball in the X-axis direction connecting the bottom of the first Gothic arch groove shape and the bottom of the second Gothic arch groove shape including two arcuate curves on the screw shaft side, and the nut side A third Gothic arch groove bottom including one arcuate curve of the screw shaft and the one arcuate curve of the screw shaft side, the other arcuate curve of the nut side and the other arcuate curve of the screw shaft side The amount of movement of the ball in the Y-axis direction perpendicular to the X-axis direction connecting the bottom of the fourth Gothic arch groove shape including is equal.

  According to a fourth aspect of the present invention, in the ball screw according to the second or third aspect, the cross-sectional shape of the unloaded return path of the circulation member is larger than the radius of the ball over the entire length in the length direction. It includes a total of four arc-shaped curves with a large radius of curvature.

  According to a fifth aspect of the present invention, there is provided a screw shaft having a spiral ball rolling groove on the outer peripheral surface, and two arcuate shapes facing the ball rolling groove of the screw shaft and having a radius of curvature larger than the radius of the ball. A nut having a spiral loaded ball rolling groove having a cross-sectional shape of a Gothic arch groove shape including a curve on the inner peripheral surface, and one end and the other end of the load ball rolling groove of the nut are connected, and the circumference of the ball And a plurality of balls arranged in the loaded ball rolling groove of the nut and the unloaded return path. Over the entire length of the load return path, the cross-sectional shape of the unloaded return path includes four arc-shaped curves with a radius of curvature larger than the radius of the ball, and the two arc-shaped curves on the nut side Including first Gothic arch groove shaped bottom and The movement amount of the ball in the X-axis direction connecting the bottom of the second Gothic arch groove shape including two arc-shaped curves on the screw shaft side, one arc-shaped curve on the nut side, and the screw shaft side And a bottom of the fourth Gothic arch groove shape including the other arcuate curve on the nut side and the other arcuate curve on the screw shaft side. And the ball movement amount in the Y-axis direction orthogonal to the X-axis direction is the same ball screw.

  According to a sixth aspect of the present invention, in the ball screw according to any one of the first to fifth aspects, the circulating member passes the pipe through the hole of the die and the die is inserted in the state where the tool is put inside the pipe. It is manufactured by pulling out from

  The invention described in claim 7 is a screw shaft having a spiral ball rolling groove on the outer peripheral surface, and two arcuate shapes facing the ball rolling groove of the screw shaft and having a radius of curvature larger than the ball radius. A nut having a spiral loaded ball rolling groove having a cross-sectional shape of a Gothic arch groove shape including a curve on the inner peripheral surface, and one end and the other end of the load ball rolling groove of the nut are connected, and the circumference of the ball In a ball screw manufacturing method comprising: a circulating member having an unloaded return path having a cross-sectional shape of a closed curve that surrounds; and a plurality of balls arranged in the loaded ball rolling groove and the unloaded return path of the nut, By passing the pipe through the hole of the die and pulling out the pipe with the tool inside the pipe, a no-load return path is formed on the inner peripheral surface of the pipe, and the cross section of the no-load return path is formed on the nut. The load baud A ball screw comprising: a step of forming a Gothic arch groove shape in which the cross-sections of rolling grooves are combined; a step of bending both end portions in the length direction of the circulation member; and a step of attaching the circulation member to the nut. It is a manufacturing method.

  If the cross-sectional shape of the no-load return path of the circulation member is formed by a single arc, the center position of the ball when the ball approaches the wall surface of the no-load return path cannot be determined. However, when the cross-sectional shape of the unloaded return path is formed in a Gothic arch groove shape including two arcuate curves, the center position of the ball when the ball approaches the wall surface of the unloaded return path is determined. By forming the cross-sectional shape of the unloaded return path of the circulation member into a Gothic arch groove shape that matches the cross-sectional shape of the loaded ball rolling groove of the nut, it is possible to prevent the meandering of the ball in the unloaded return path. Since the balls correctly aligned on the unloaded return path move to the loaded ball rolling groove, the balls can be circulated smoothly and the running noise of the balls can be reduced.

  FIG. 1 shows a perspective view of a ball screw according to a first embodiment of the present invention. The ball screw includes a screw shaft 1 having a spiral ball rolling groove 1a formed on the outer peripheral surface, and a nut having a spiral load ball rolling groove 2a facing the ball rolling groove 1a on the inner peripheral surface. 2 and a plurality of balls 3 (see FIG. 2) interposed between the ball rolling groove 1a of the screw shaft 1 and the loaded ball rolling groove 2a (see FIG. 2) of the nut 2 so as to allow rolling motion. Prepare.

  A ball rolling groove 1a of a predetermined lead is formed on the outer peripheral surface of the screw shaft 1 by grinding or rolling. As shown in FIG. 3, the cross-sectional shape of the ball rolling groove 1 a is formed in a Gothic arch groove shape including two arcs 4 having a radius slightly larger than the radius of the ball 3. The centers C1 of the two arcs are located at a position away from the center C2 of the ball 3. The ball 3 contacts the ball rolling groove 1a having a Gothic arch groove shape at two points. The contact angle θ formed by the line L1 connecting the center C2 of the ball 3 and the bottom 5 of the gothic arch groove and the line connecting the contact point 6 between the arc 4 and the ball 3 and the center C2 of the ball 3 is, for example, 40 Set to ~ 50 degrees. The ball rolling groove 1a is ground after being heat-treated. Arc-shaped chamfers 7 may be formed on both side edges of the ball rolling groove 1a, or a relief groove serving as a relief during grinding may be formed on the bottom 5 of the gothic arch groove.

  FIG. 2 shows a perspective view of the nut 2 with the screw shaft 1 removed. A through hole 2 e through which the screw shaft 1 passes is formed in the nut 2. A flange 2b for attaching the nut 2 to the other machine part is formed at one end of the nut 2 in the axial direction. Mounting holes 9 are formed in the flange 2b at equal intervals in the circumferential direction. A flat chamfered portion 2 c is formed on the outer peripheral surface of the nut 2. Two return pipes 8 that are circulation members are attached to the flattening portion 2c. A through hole 2d that penetrates to the inner peripheral surface of the nut 2 is opened in the flattening portion 2c. Both ends of the return pipe 8 bent into a gate shape are inserted into the through hole 2d. The return pipe 8 attached to the flattening portion 2 c is fixed to the nut 2 by a return pipe presser 11. On the inner peripheral surface of the nut 2, a spiral loaded ball rolling groove 2a having a predetermined lead is formed by grinding. As shown in FIG. 3, the cross-sectional shape of the loaded ball rolling groove 2 a is formed in a Gothic arch groove shape including two arcs having a radius slightly larger than the radius of the ball 3. Since the Gothic arch groove shape is the same as that of the ball rolling groove 1a of the screw shaft 1, the same reference numerals are given and description thereof is omitted. The loaded ball rolling groove 2a is ground and then heat-treated.

  As shown in FIG. 2, an unloaded return path 14 that connects one end and the other end of the loaded ball rolling groove 2 a of the nut 2 is formed on the inner periphery of the return pipe 8. The configuration of the no-load return path 14 will be described later. At both ends in the lengthwise direction of the return pipe 8, the balls 3 rolling between the ball rolling grooves 1 a of the screw shaft 1 and the loaded ball rolling grooves 2 a of the nut 2 are scooped up into the no-load return path 14. A raised portion 12 is formed. The ball 3 that rolls to one end of the loaded ball rolling groove 2 a of the nut 2 is guided into the no-load return path 14 by the lifting portion 12 of the return pipe 8. After passing through the no-load return path 14 of the return pipe 8, the ball 3 is returned to the loaded ball rolling groove 2 a of the nut 2 from the lifting portion 12 on the opposite side of the return pipe 8.

  As shown in FIG. 3, in the loaded ball rolling path between the ball rolling groove 1 a of the screw shaft 1 and the loaded ball rolling groove 2 a of the nut 2, the ball 3 is a ball rolling groove 1 a of the screw shaft 1. And a load ball rolling groove 2a of the nut 2 to receive a compressive load. On the other hand, in the no-load return path 14 of the return pipe 8, there is a slight play around the ball 3, and a slight gap is opened between the ball 3 and the no-load return path 14. When the screw shaft 1 is rotated relative to the nut 2, the ball 3 rolls while receiving a compressive load in the loaded ball rolling path. On the other hand, in the unloaded return path 14 of the return pipe 8, the ball 3 moves while being pushed by the subsequent ball 3.

  As shown in FIG. 4, the spiral loaded ball rolling path between the ball rolling groove 1 a of the screw shaft 1 and the loaded ball rolling groove 2 a of the nut 2, and the unloaded return path 14 of the return pipe 8. Are arranged with a plurality of balls 3. In this embodiment, two return pipes 8 are provided in order to increase the number of turns of the load ball rolling path.

  5 and 6 show the return pipe 8 attached to the nut 2. As described above, the lifting portions 12 that scoop up the balls 3 that roll between the screw shaft 1 and the nut 2 are formed at both ends of the return pipe 8 in the longitudinal direction. The cross-sectional shape of the load ball rolling groove 2a of the nut 2 is formed into a Gothic arch groove shape composed of two arcs. For this reason, in the load ball rolling groove 2a, a valley bottom line 15 (see FIG. 6) formed by the intersection of two arcs is formed.

  7 and 8 are detailed views of the return pipe 8. Both end portions of the return pipe 8 are continuous with the load ball rolling groove 2 a of the nut 2. The cross-sectional shape of the no-load return path 14 of the return pipe 8 is formed as a closed curve surrounding the ball 3.

  FIG. 9 shows a return pipe 8 attached to the nut 2 and a sectional view thereof. The cross-sectional shape of the no-load return path 14 at both ends 8a of the return pipe 8 is a portion 16 on the nut 2 side connected to the loaded ball rolling groove 2a of the nut 2 (region on the nut side across the Y axis in the figure). And a portion 17 on the screw shaft 1 side (a region on the screw shaft side across the Y axis in the drawing). The portion 16 on the nut 2 side of the unloaded return path 14 is formed in a Gothic arch groove shape that matches the shape of the loaded ball rolling groove 2 a of the nut 2. For this reason, in the portion 16 on the nut 2 side of the no-load return path 14, a bottom line 15 (see FIGS. 7 and 8) formed by the intersection of the two arcs 18 is formed. Similarly to the nut 2 side portion, the screw shaft 1 side portion 17 is also formed in a Gothic arch groove shape including two arcs 19 having a radius larger than the radius of the ball 3. 9 shows an example in which the scooping portion 12 of the return pipe 8 is provided with a lip 12a that abuts against the balls 3 and the spacers between the balls 3. However, as shown in FIG. 7 and FIG. 12 may not be provided with the lip 12a.

  FIG. 10 shows a detailed view of the cross section of the return pipe 8. Both the nut 2 side portion 16 and the screw shaft 1 side portion 17 sandwiching the Y axis of the no-load return path 14 at both ends 8a of the return pipe 8 are formed in a Gothic arch groove shape. For this reason, the cross-sectional shape of the unloaded return path 14 includes a total of four arcs 18 and 19 having a radius R slightly larger than the radius of the ball 3. The arcs 18 and 19 are formed with the same radius R, one for each of the four regions (quadrants) partitioned by the XY axes. A first Gothic arch groove-shaped bottom 21 including the two arcs 18 on the nut 2 side (the valley bottom line 15) and a second Gothic arch-shaped bottom including two arcs on the screw shaft 1 side. 22 is the X axis, the third gothic arch groove bottom 23 including one arc 18 on the nut 2 side and one arc 19 on the screw shaft 1 side, and the other on the nut 2 side. A line connecting the arc 18 and the bottom 24 of the fourth Gothic arch groove shape including the other arc 19 on the screw shaft 1 side is defined as a Y axis. The amount of movement of the ball 3 in the X-axis direction (the amount of movement in the X-axis direction from when the ball 3 contacts the first Gothic arch groove shape until it contacts the second Gothic arch groove shape), and in the Y-axis direction The amount of movement of the ball 3 (the amount of movement in the Y-axis direction from when the ball 3 abuts on the third Gothic arch groove shape until it abuts on the fourth Gothic arch groove shape) is set equal. The cross-sectional shape of the unloaded return path 14 of the return pipe 8 includes four arcs 18 and 19 having a radius larger than the radius of the ball 3 over the entire length in the length direction as well as both ends 8a.

  As shown in FIG. 10, when the cross-sectional shape of the unloaded return path 14 of the return pipe 8 is constituted by a single circular arc 26 (indicated by a one-dot chain line in the figure), the ball 3 of the unloaded return path 14 The center position of the ball 3 when approaching the wall surface is not determined. The center position of the ball 3 draws an arc locus P2. However, when the cross-sectional shape of the unloaded return path 14 is formed in a Gothic arch groove shape including two arcs 18, the center position of the ball 3 when the ball 3 approaches the wall surface of the unloaded return path 14 is a single point P1. It is decided. By forming the cross-sectional shape of the unloaded return path 14 of the return pipe 8 into a Gothic arch groove shape that matches the sectional shape of the loaded ball rolling groove 2a of the nut 2, the meandering of the ball 3 in the unloaded return path 14 is prevented. You can see that you can. As shown in FIG. 9, the balls 3 correctly aligned in the no-load return path 14 of the return pipe 8 move to the loaded ball rolling groove 2a, so that the balls 3 can be smoothly circulated. By aligning the balls 3, the running sound of the balls 3 can be reduced.

  As shown in FIG. 10, the no-load return path 14 is composed of four arcs 18, 19, so that the no-load return path 14 is made into the ball rolling groove 1 a of the screw shaft 1 and the loaded ball rolling groove of the nut 2. The shape and size can be approximated to 2a. Therefore, it is possible to further align the balls 3 moving from the no-load return path 14 to the loaded ball rolling path. Further, by making the movement amounts of the balls 3 in the X-axis direction and the Y-axis direction in the cross section of the no-load return path 14 equal, the balls 3 can be more aligned in the no-load return path 14. Furthermore, the cross-sectional shape of the no-load return path 14 of the return pipe 8 is composed of four arcs 18 and 19 over the entire length in the length direction, so that a ball that moves from the no-load return path 14 to the loaded ball rolling path 3, the balls 3 moving in the middle of the no-load return path 14 can be aligned, and the balls 3 can be circulated more smoothly.

  FIG. 11 is a manufacturing process diagram of the return pipe 8. A circular metal pipe 31 is prepared as a material (FIG. 11A). As shown in FIG. 12, the metal pipe 31 is passed through a die 32 and drawn. In the drawing process of the pipe 31, a tool 33 for finishing the outer diameter, the inner diameter and the wall thickness to the required dimensions is inserted into the pipe 31. Inserting a tool called shinkin and pulling it out together with the pipe. Pulling out the tie with the plug fixed with a support rod. Floating plug that keeps the balance autonomously without holding the plug. A method such as pulling is used. In this embodiment, floating plug drawing using a plug as a tool is shown. Four arcs 18 and 19 are formed on the inner diameter of the drawn pipe 34 (FIG. 11B). Next, both ends of the pipe 34 are bent by a bending machine (FIG. 11C). Both ends of the pipe 34 are bent according to the lead of the screw shaft 1. As described above, the return pipe 8 is manufactured.

  Various other methods of manufacturing the return pipe 8 are conceivable. For example, it is possible to form by splitting the return pipe into two types and combining them after forming each half, or by so-called injection molding. Further, the material of the return pipe is not limited to metal, and resin can also be used.

  As described above, in the no-load return path 14 of the return pipe 8, a slight clearance is opened around the ball 3 (see FIG. 10). On the other hand, in the loaded ball rolling groove 2a of the nut 2, the ball 3 comes into contact with the loaded ball rolling groove 2a (see FIG. 3). For this reason, the Gothic arch groove of the unloaded return path 14 of the return pipe 8 is formed to have a slightly larger diameter than the Gothic arch groove of the loaded ball rolling groove 2 a of the nut 2. For this reason, even if the cross-sectional shape of the portion on the nut 2 side of the unloaded return path 14 of the return pipe 8 is matched with the Gothic arch groove shape of the loaded ball rolling groove 2a of the nut 2, there is a slight gap between them. A step is generated. In order to eliminate this level difference, as shown in FIG. 13, a chamfer 35 may be given to the load ball rolling groove 2 a of the nut 2. Further, both end portions 8a of the return pipe 8 may be slightly moved toward the screw shaft 1 as indicated by arrows in the drawing.

  The present invention is not limited to the above-described embodiment, and can be applied to other embodiments without departing from the scope of the present invention. For example, the present invention is not limited to application to a return pipe type ball screw. If the no-load return path has a closed cross section, it is applied to an end cap type ball screw that has a through-hole extending in the axial direction in the nut and a lid member having a direction change path at both ends in the axial direction of the nut. can do.

  The cross-sectional shape of the screw shaft side portion of both ends of the return pipe in the lengthwise direction of the no-load return path may not be formed in a Gothic arch groove shape, but may be formed in a single arc shape. In this case, the ball is surrounded by three arcs.

  You may comprise the cross-sectional shape of the outer diameter of a return pipe from four circular arcs of a shape similar to an inner diameter. Since the number of contact points between the outer diameter of the return pipe and the nut is reduced, noise reduction can be further promoted.

  The Gothic arch groove shape may be composed of two spline curves, two clothoid curves, etc., as long as it is a curve that can contact the ball at two points, even though it is not composed of two arcs.

The perspective view of the ball screw of a first embodiment of the present invention. Nut perspective view Sectional view showing the ball sandwiched between the screw shaft and the nut Side view showing screw shaft and return pipe Perspective view of nut with return pipe attached Cross section of nut with return pipe attached Detailed view of VI part in Fig. 6 Detailed view of VI part in Fig. 6 Front view showing the return pipe attached to the nut, and a sectional view of the return pipe Detailed view of the cross section of the return pipe Return pipe manufacturing process diagram Diagram showing pipe drawing Sectional view of the return pipe attached to the nut as seen from the axial direction of the nut

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Screw shaft, 1a ... Ball rolling groove, 2 ... Nut, 2a ... Loaded ball rolling groove, 3 ... Ball, 8 ... Return pipe (circulation member), 14 ... Unloaded return path, 16 ... Return pipe nut 17 part on the screw shaft side of the return pipe, 18, 19 ... arc (arc-shaped curve), 21 ... bottom of the first Gothic arch groove shape, 22 ... bottom of the second Gothic arch groove shape, 23 ... Bottom of third gothic arch groove shape, 24 ... Bottom of fourth gothic arch groove shape, 31 ... Pipe, 32 ... Dies, 33 ... Tool

Claims (7)

A screw shaft having a spiral ball rolling groove on the outer peripheral surface;
Opposite to the ball rolling groove of the screw shaft, the inner peripheral surface has a spiral loaded ball rolling groove having a cross-sectional shape of a Gothic arch groove shape including two arc-shaped curves having a radius of curvature larger than the radius of the ball. With nuts,
A circulating member that connects one end and the other end of the loaded ball rolling groove of the nut and has a no-load return path having a cross-sectional shape of a closed curve surrounding the periphery of the ball;
A plurality of balls arranged in the loaded ball rolling groove of the nut and the unloaded return path,
The cross-sectional shape of the end of the circulation member in the lengthwise direction of the unloaded return path connected to the load ball rolling groove of the nut is the cross-sectional shape of the load ball rolling groove of the nut. A ball screw formed into a combined Gothic arch groove shape. The cross-sectional shape of the screw shaft side portion of the end portion of the circulation member in the lengthwise direction of the unloaded return path has a Gothic arch groove shape including two arc-shaped curves having a radius of curvature larger than the radius of the ball. Formed,
2. The ball according to claim 1, wherein the cross-sectional shape of the end portion in the length direction of the unloaded return path of the circulation member includes a total of four arcuate curves having a radius of curvature larger than the radius of the ball. screw. In the cross section of the end portion in the length direction of the no-load return path of the circulation member,
The X-axis direction connecting the bottom of the first Gothic arch groove shape including the two arc-shaped curves on the nut side and the bottom of the second Gothic arch groove shape including the two arc-shaped curves on the screw shaft side The amount of movement of the ball at
A bottom of a third Gothic arch groove shape including one arcuate curve on the nut side and one arcuate curve on the screw shaft side; the other arcuate curve on the nut side and the other on the screw shaft side; 3. The movement amount of the ball in the Y-axis direction perpendicular to the X-axis direction, which connects the bottom of the fourth Gothic arch groove shape including the arc-shaped curve, is equal to claim 2. Ball screw.   The cross-sectional shape of the unloaded return path of the circulation member includes a total of four arc-shaped curves having a radius of curvature larger than the radius of the ball over the entire length in the length direction. 3. A ball screw according to 3. A screw shaft having a spiral ball rolling groove on the outer peripheral surface;
Opposite to the ball rolling groove of the screw shaft, the inner peripheral surface has a spiral loaded ball rolling groove having a cross-sectional shape of a Gothic arch groove shape including two arc-shaped curves having a radius of curvature larger than the radius of the ball. With nuts,
A circulating member that connects one end and the other end of the loaded ball rolling groove of the nut and has a no-load return path having a cross-sectional shape of a closed curve surrounding the periphery of the ball;
A plurality of balls arranged in the loaded ball rolling groove of the nut and the unloaded return path,
Over the entire length of the unloaded return path of the circulation member in the length direction, the cross-sectional shape of the unloaded return path includes four arc-shaped curves having a radius of curvature larger than the radius of the ball,
The X-axis direction connecting the bottom of the first Gothic arch groove shape including the two arc-shaped curves on the nut side and the bottom of the second Gothic arch groove shape including the two arc-shaped curves on the screw shaft side The third gothic arch groove bottom including the amount of movement of the ball, one arc-shaped curve on the nut side and one arc-shaped curve on the screw shaft side, and the other arc-shaped curve on the nut side And a ball screw having the same amount of movement of the ball in the Y-axis direction orthogonal to the X-axis direction, connecting the bottom of the fourth Gothic arch groove shape including the other arcuate curve on the screw shaft side.   6. The ball according to claim 1, wherein the circulating member is manufactured by passing a pipe through a hole of a die and pulling the pipe out of the die with a tool inserted inside the pipe. screw. A screw shaft having a spiral ball rolling groove on the outer peripheral surface, and a cross section of a Gothic arch groove shape including two arc-shaped curves facing the ball rolling groove of the screw shaft and having a radius of curvature larger than the radius of the ball A non-load having a closed curved cross-sectional shape surrounding the ball by connecting a nut having a spiral loaded ball rolling groove having an inner shape to one end and the other end of the load ball rolling groove of the nut In a ball screw manufacturing method comprising: a circulating member having a return path; and a plurality of balls arranged in the loaded ball rolling groove of the nut and the no-load return path,
By passing the pipe through the hole of the die and pulling out the pipe with the tool inside the pipe, a no-load return path is formed on the inner peripheral surface of the pipe, and the cross section of the no-load return path is formed on the nut. Forming a Gothic arch groove shape that matches the cross-sectional shape of the load ball rolling groove;
Bending both ends in the length direction of the circulation member;
Attaching the circulating member to the nut, and a ball screw manufacturing method.

Images