JP6915004B2 - Ball circulation parts - Google Patents

Description

The present invention relates to a ball circulation component provided in a ball type moving mechanism such as a ball screw device or a linear motion guide device and having a hollow component for circulating the ball.

The ball-type moving mechanism arranges a plurality of balls between the shaft body and the relative moving body, and rolls the balls to smoothly move the shaft body and the relative moving body relative to each other. Typical examples of the ball-type moving mechanism include a linear motion guide device, a linear bush device, a ball screw device, and the like.

The linear motion guide device has a rod-shaped guide rail as a shaft body and a slider as a relative moving body. A shaft-side ball rolling groove is formed along the longitudinal direction on the outer surface of the guide rail, and a moving body-side ball rolling groove is also formed inside the slider. By facing the shaft-side ball rolling groove and the moving body-side ball rolling groove, a linear passage (ball rolling path) in which a plurality of balls roll is formed. A ball circulation path for circulating balls is formed in the relative moving body.

The linear bush device has a rod-shaped guide rail as a shaft body and a slider as a relative moving body. Inside the slider, a ball rolling path is formed so that a part of the ball protrudes toward the shaft body. The ball held in the ball rolling path of the slider makes point contact with the outer peripheral surface of the shaft body. A ball circulation path is formed in the relative moving body to circulate the ball moving in the ball rolling path.

The ball screw device has a rod-shaped screw shaft as a shaft body and a nut as a relative moving body, and a spiral shaft-side ball rolling groove is formed on the outer surface of the screw shaft to form an inner circumference of the nut. A spiral-shaped ball rolling groove on the moving body side is formed. By facing the shaft-side ball rolling groove and the moving body-side ball rolling groove, a spiral passage (ball rolling path) in which a plurality of balls roll is formed. A ball circulation path for circulating balls is formed in the nut. The ball screw device includes an end cap method, a top method, a return tube method, a guide plate method, and the like as a ball circulation method. The end cap method is a method in which ball circulation parts serving as end caps are arranged at both ends of the nut to circulate the balls. In the top method, a ball circulation component that serves as a top is embedded in the outer circumference of the nut, and the ball is returned to the original groove by overcoming the land portion of the screw shaft for each lead. The return tube method is a method in which a ball circulation component having a ball circulation tube (return tube) is assembled from the outer circumference of the nut. The guide plate method is a method in which a guide plate or deflector having the same function is embedded in the nut instead of the return tube. This ball circulation path may be configured by combining a plurality of guide plates and deflectors.

As described above, the ball circulation path formed in the relative moving body scoops up the ball from one end of the ball rolling path, transfers the ball to the other end of the ball rolling path while changing the direction of the ball, and rolls the ball. The structure will be resupplied to the flow path. As a result, a plurality of balls can be infinitely circulated by the ball rolling path and the ball circulation path.

An impact is applied to the ball circulation path when the ball is scooped up, and wear occurs when the ball suddenly changes direction. Therefore, the whole or a part of the ball circulation path is composed of a dedicated ball circulation component, and the ball circulation component is incorporated into the relative moving body so that the ball circulation path can be replaced or maintained as needed.

The ball circulation component generally has a complicated three-dimensional shape because an opening (referred to as a tongue portion or a lip portion) for scooping up the ball and a winding ball circulation path are formed in the ball circulation component. Although resin is also used as a material for ball circulation parts, metal is preferable for the purpose of improving heat resistance and wear resistance and for realizing assembly by press fitting or caulking. Therefore, the ball circulation component is manufactured by machining using a machining center or by a metal powder injection molding method (MIM (Metal Injection Molding)) (see Patent Document 1). The metal powder injection molding method is a method in which a metal powder and a binder containing a resin or the like are mixed and kneaded as a raw material and injection molded into a mold, and then the binder is degreased and sintered. It is a technology for manufacturing metal products.

Japanese Patent No. 5477513

The metal powder injection molding method has an advantage that ball circulation parts having a complicated shape can be efficiently mass-produced. However, it is difficult to manage the state of the inner wall of the ball circulation path because the ball circulation path is complicatedly winding inside the component. Further, even if an attempt is made to reduce the rolling resistance of the ball in the ball circulation path, the surface roughness of the inner wall of the ball circulation path is limited by the specifications of the metal injection molding method.

The present invention has been made in view of the above problems, and while improving the durability of ball circulation parts manufactured by the metal powder injection molding method, the surface roughness of the inner wall of the ball circulation path can be reduced. An object of the present invention is to provide a ball circulation component that can easily manage the condition of the inner wall.

The present invention that achieves the above object is to roll a plurality of balls in the gap between the shaft body and the relative moving body arranged with a gap with respect to the shaft body, thereby moving the shaft body and the relative movement. It is installed on the relative moving body in the ball-type moving mechanism that moves the body relative to each other, and forms at least a part of the ball circulation path that circulates the ball between one end and the other end of the ball rolling path formed in the gap. A ball circulation component that is formed by a metal powder injection molding method and has a first circulation groove that defines the ball circulation path, and a ball circulation component that is formed by a metal powder injection molding method. A second component piece having a second circulation groove to be defined is provided, and the first component piece and the second component piece are combined in a posture in which the first circulation groove and the second circulation groove face each other. The ball circulation component is characterized in that the ball circulation path is formed by the first circulation groove and the second circulation groove.

The surface roughness of the first circulation groove and the second circulation groove is set to 6.3 Ra or less in relation to the ball circulation component.

The first circulation groove and the second circulation groove are surface-treated in relation to the ball circulation component.

In relation to the ball circulation component, the first circulation groove and the second circulation groove are machined with a allowance of 0.5 mm or less.

In connection with the ball circulation component, one end of the ball circulation path is provided with a one-sided opening that faces the ball rolling path and scoops up the ball from the ball rolling path. The bottom point closest to the valley bottom of the ball rolling path in the above, and the boundary between the first component piece and the second component piece are inconsistent.

In relation to the ball circulation component, a boundary between the first component piece and the second component piece is formed at a position different from the bottom point in the one-side opening.

In connection with the ball circulation component, one end of the ball circulation path is provided with a one-sided opening facing the ball rolling path and scooping the ball from the ball rolling path, and the one-sided opening. It is characterized in that the highest point farthest from the valley bottom of the ball rolling path in the above and the boundary between the first component piece and the second component piece do not match.

In relation to the ball circulation component, a boundary between the first component piece and the second component piece is formed at a position different from the highest point in the one-side opening.

In connection with the ball circulation component, one end of the ball circulation path is provided with a one-sided opening facing the ball rolling path and scooping the ball from the ball rolling path, and the one-sided opening. Is characterized in that a boundary between the first component piece and the second component piece is not formed.

In connection with the ball circulation component, the first component piece has a first contact surface continuous from the edge of the first circulation groove, and the second component piece is from the edge of the second circulation groove. It is characterized by having a second contact surface that is continuous and in contact with the first contact surface.

In relation to the ball circulation component, the angle formed by the first circulation groove and the first contact surface at the edge is an obtuse angle or an acute angle.

In connection with the ball circulation component, one of the first contact surface and the second contact surface is provided with a coupling projection, and the first contact surface and the second contact surface are provided with a coupling projection. A coupling recess is provided on either one or the other, and the first component piece and the second component piece are bonded by fitting the coupling projection and the coupling recess together by press fitting.

In relation to the ball circulation component, the protrusion direction of the coupling protrusion is not perpendicular to the plane of either the first contact surface or the second contact surface continuous with the base end of the coupling protrusion. It is characterized by being.

In connection with the ball circulation component, one of the first contact surface and the second contact surface is provided with a cone-shaped positioning protrusion, and the first contact surface and the second contact surface are provided. A mortar-shaped positioning recess is provided on either one of the contact surfaces, and the relative position of the first component piece and the second component piece is determined by engaging the positioning projection with the positioning recess. It is characterized by being done.

In relation to the ball circulation component, the protruding direction of the positioning protrusion is not perpendicular to the plane of either the first contact surface or the second contact surface continuous with the base end of the positioning protrusion. It is characterized by being.

In relation to the ball circulation component, the first circulation groove and the edge of the first contact surface are curved.

In relation to the ball circulation component, the edge of the first circulation groove is characterized in that when it transitions in the axial direction of the central axis of the ball circulation path, the phase does not change with the bending direction of the central axis as a reference phase. And.

According to the present invention, it is possible to manufacture a ball circulation component that can reduce the surface roughness of the inner wall of the ball circulation path and easily control the state of the inner wall while improving the durability by the metal powder injection molding method. It can produce excellent effects.

It is (A) plan view and (B) plane partial sectional view which shows the whole structure of the ball screw device to which the ball circulation component which concerns on 1st Embodiment of this invention is applied. It is (A) plan view, (B) right side view, (C) rear view, (D) bottom view of the ball circulation component. It is (A) plan view, (B) right side view, (C) rear view, (D) bottom view which shows only the ball circulation path of the ball circulation component virtually. It is (A) plan view, (B) right side view, (C) rear view, (D) bottom view which shows the 1st part piece of the ball circulation component. It is (A) plan view and (B) rear view which shows the assembly process of the ball circulation component. (A) is a plan view schematically explaining the phase of the boundary on the inner peripheral side formed in the ball circulation path of the ball circulation component, (B) is a rotary cross-sectional view taken along the line BB of (A), ( C) is a rotational sectional view taken along the line CC of (A), (D) is a plan view of the first ball circulation groove constituting the ball circulation path, and (E) is a second ball constituting the ball circulation path. It is a top view of a circulation groove. It is (A) plan view, (B) right side view, (C) rear view, (D) bottom view which shows the modification of the ball circulation component which concerns on 1st Embodiment. It is (A) plan view, (B) right side view, (C) rear view, (D) bottom view which shows the modification of the ball circulation component which concerns on 1st Embodiment. It is (A) front partial sectional view and (B) plan view which shows the whole structure of the ball screw device to which the ball circulation component which concerns on 2nd Embodiment of this invention is applied. (A) is a plan view, front view, bottom view, and left side view of the ball circulation component, and (B) is a plan view, front view, bottom view, and left side view of the second component piece of the ball circulation component. Is. It is (A) plan view and (B) bottom view which shows the state which assembles the ball circulation component by combining the 1st component piece and the 2nd component piece. It is (A) front partial sectional view and (B) plan view which shows the whole structure of the ball screw device to which the ball circulation component which concerns on 3rd Embodiment of this invention is applied. It is (A) front view, (B) left side view, (C) right side view, (D) rear view, (E) plan view, (F) bottom view of the ball circulation component. (A) is a six-view view of the first component piece of the ball circulation component, and (B) is a six-view view of the second component piece of the ball circulation component. It is a right side view which shows the state which shows the state which made up the ball circulation component by combining the 1st component piece and the 2nd component piece. A modified example of the ball circulation component of the third embodiment is shown, (A) front view, (B) left side view, (C) right side view, (D) rear view, (E) plan view, (F). It is a bottom view. (A) is a six-view view of the first component piece of the modified example, and (B) is a six-view view of the second component piece. It is (A) plan view and (B) right side view which shows the state which the ball circulation component is formed by combining the 1st component piece and the 2nd component piece.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Although the ball screw device is illustrated here as the ball-type moving mechanism, the present invention is not limited to this, and can be applied to a linear motion guiding device and other moving mechanisms.

(First Embodiment)

FIG. 1 shows a ball screw device 1 in which the ball circulation component 30 according to the first embodiment is incorporated. The ball screw device 1 of the present embodiment includes a screw shaft 2 as a shaft body, a nut 8 as a relative moving body, a plurality of balls 18 rolling between the screw shaft 2 and the nut 8, and a plurality of balls incorporated in the nut 8. It has a ball circulation component 30.

The screw shaft 2 is a rod-shaped member generally made of metal and having a circular cross section, and a shaft-side ball rolling groove 4 is spirally formed on the outer peripheral surface. The shape of the cross section of the shaft-side ball rolling groove 4 orthogonal to the groove longitudinal direction (spiral direction) is, for example, a partial arc shape or a V-shape having an angle range of less than 180 degrees.

The nut 8 is a cylindrical member generally made of metal, and the screw shaft 2 is inserted into the cylinder. A ball rolling groove 10 on the moving body side is spirally formed on the inner peripheral surface of the nut 8. The spiral direction, pitch, lead angle, and the like of the moving body-side ball rolling groove 10 coincide with those of the shaft-side ball rolling groove 4. As a result, the ball rolling groove 10 on the moving body side and the ball rolling groove 4 on the shaft side face each other to form a ball rolling path 20 in which the ball 18 rolls in a spiral shape. The shape of the cross section of the moving body-side ball rolling groove 10 orthogonal to the groove longitudinal direction (spiral direction) is, for example, a partial arc shape or a V-shape having an angle range of less than 180 degrees. The cross-sectional shape of the groove is not particularly limited, and various shapes can be adopted as long as the ball 18 can roll without coming off the groove.

A component accommodating space 12 is formed in the nut 8. The component accommodating space 12 is a through hole in the radial direction facing the outer peripheral surface of the screw shaft 2. By accommodating and fixing the ball circulation component 30 in the component accommodating space 12, the ball circulation component 30 can face the outer peripheral surface of the screw shaft 2. Although the details will be described later, the ball circulation component 30 is formed with a tubular ball circulation path 90 connecting both ends of the ball rolling path 20.

The ball 18 becomes a metal sphere. A plurality of balls 18 are connected along the ball rolling path 20 and the ball circulation path 90 in a state where almost no gap is formed with each other.

The ball rolling path 20 formed at the boundary (gap) between the screw shaft 2 and the nut 8 and the ball circulation path 90 formed on the nut 8 side form a conduit for infinitely looping the ball 18. When the screw shaft 2 and the nut 8 are relatively rotated, the ball 18 circulates infinitely in the ball rolling path 20 and the ball circulation path 90, and the screw shaft 2 and the nut 8 move relative to each other in the axial direction. The ball circulation component 30 is circulated by returning the ball 18 by about 2 leads of the screw shaft 2 through the ball circulation path 90. Such a ball screw device 1 may be referred to as a guide plate system, and the ball circulation component 30 may be referred to as a deflector.

FIG. 2 shows the ball circulation component 30 in an enlarged manner. The ball circulation component 30 includes a first component piece 40 and a second component piece 70. The first component piece 40 is formed by a metal powder injection molding method and has a first circulation groove 50 that defines a ball circulation path 90. The second component piece 70 is also formed by the metal powder injection molding method and has a second circulation groove 80 that defines the ball circulation path 90.

By combining the first component piece 40 and the second component piece 70 in a posture in which the first circulation groove 50 and the second circulation groove 80 face each other (see FIG. 5), the first circulation groove 50 and the second circulation groove 80 A tubular ball circulation path 90 is configured. In the ball circulation component 30 of the first embodiment, the ball circulation path 90 has a completely tubular shape, and the internal space thereof can be seen only through the openings at both ends. However, the present invention is not limited to this, and slits, notches, and penetrations are made in the first component piece 40 and / or the second component piece 70 so that a part of the tubular shape of the ball circulation path 90 is exposed to the outside. Holes may be formed. That is, a structure in which a part of the ball circulation path 90 is open to the outside may be used.

The ball circulation component 30 has an outer peripheral side boundary 31 that separates the first component piece 40 and the second component piece 70 on the outer peripheral surface. Further, the inner peripheral surface of the ball circulation path 90 also has an inner peripheral side boundary 32 (see FIGS. 2C and 3) that separates the first component piece 40 and the second component piece 70.

FIG. 3 shows a state in which only the ball circulation path 90 is virtually extracted. The inner peripheral side boundary 32 that separates the first component piece 40 and the second component piece 70 specifically has one inner peripheral side boundary 32A and the other inner peripheral side boundary 32B. When the central axis 90A passing through the center of the ball circulation path 90 is indicated by a chain double-dashed line, the cross-sectional shape of the ball circulation path 90 orthogonal to the central axis 90A is substantially a perfect circle. With respect to this cross section (perfect circle), a pair of points where one inner peripheral boundary 32A and the other inner peripheral boundary 32B intersect are set so as to always maintain a phase difference of 180 degrees from each other. Further, the phases of the one inner peripheral side boundary 32A and the other inner peripheral side boundary 32B in this cross section (perfect circle) are in phase even if they are shifted along the central axis 90A when the bending direction of the central axis 90A is used as the reference phase. It is set to the state that does not change. In other words, the one inner peripheral side boundary 32A and the other inner peripheral side boundary 32B have the bending direction of the central axis 90A as the reference phase even if they move along the central axis 90A (no matter which cross section is cut). As long as it does not turn (the phase is fixed).

The concept of "a state in which the phase does not change with the bending direction as a reference phase" will be described in more detail with reference to FIG. FIG. 6 shows a first ball circulation path 90 (1) and a second ball circulation path 90 (2) that are relatively bent (crossed) at 45 degrees along a plane in the drawing. The one inner peripheral side boundary and the other inner peripheral side boundary formed in the first ball circulation path 90 (1) and the second ball circulation path 90 (2) are in a state of "no phase change with respect to the bending direction".

In the first ball circulation path 90 (1), one inner peripheral side boundary 32A (1) and the other inner peripheral side boundary 32B (1) are formed. In the second ball circulation path 90 (2), one inner peripheral side boundary 32A (2) and the other inner peripheral side boundary 32B (2) are formed. The boundary between the first ball circulation path 90 (1) and the second ball circulation path 90 (2) is continuous, and as shown in FIGS. 6 (D) and 6 (E), the first ball circulation path 90 (1) And the second ball circulation path 90 (2) are divided in half.

As shown in the cross-sectional state of FIG. 6B, when the first ball circulation path 90 (1) is axially viewed, the bending direction (next bending direction) of the second ball circulation path 90 (2) beyond that is The reference point k (1) at which the vector Y1 (see the arrow) and the contour of the cross-sectional view intersect is defined as the reference phase (phase zero degree). In the first ball circulation path 90 (1), if the phase of one inner peripheral boundary 32A (1) is defined as na (1) and the phase of the other inner peripheral boundary 32B (1) is defined as nb (1), here The phase na (1) is 234 degrees clockwise, and the phase nb (1) is 54 degrees (234 ° -180 degrees) in the same direction.

As shown in the cross-sectional state of FIG. 6C, when the second ball circulation path 90 (2) is axially viewed, the bending direction (bending direction) from the first ball circulation path 90 (1) in front of the second ball circulation path 90 (2). The reference point k (2) at which the vector Y2 (see the arrow) and the contour of the cross-sectional view intersect is defined as the reference phase (phase zero degree). In the second ball circulation path 90 (2), if the phase of one inner peripheral boundary 32A (2) is defined as na (2) and the phase of the other inner peripheral boundary 32B (2) is defined as nb (2), here The phase na (2) is 234 degrees clockwise, and the phase nb (2) is 54 degrees (234 ° -180 degrees) in the same direction.

As a result, the phase of the one inner peripheral side boundary 32A (1) and the other inner peripheral side boundary 32B (1) in the first ball circulation path 90 (1) and the one inner peripheral side boundary in the second ball circulation path 90 (2). The phases of 32A (2) and the other inner peripheral boundary 32B (2) coincide with each other. That is, even if the ball circulation path has a bending point in the middle of the central axis 90A, as long as the vectors Y1 and Y2 in the bending direction are the reference phases k (1) and k (2), the front and back of the bending point ( In the upstream and downstream), the phase (na, nb) of the inner peripheral boundary is always fixed. This state is defined as "a state in which the phase does not change with the bending direction as the reference phase". As shown in FIG. 3, the actual ball circulation path is three-dimensionally bent in various directions, and even such a ball circulation path 90 is finely divided along the central axis 90A. Then, it can be defined that the two-dimensional bending states as shown in FIG. 6 are continuous.

Returning to FIG. 3B, further, one end 92 of the ball circulation path 90 faces the ball rolling path 20 (shaft-side ball rolling groove 4), and the shaft-side ball rolling groove 4 to the ball 18 It is provided with a one-sided opening 92A for scooping up. The other end 94 of the ball circulation path 90 is provided with an opening 94A on the other side that faces the ball rolling path 20 (shaft-side ball rolling groove 4) and scoops up the ball 18 from the shaft-side ball rolling groove 4.

As shown in FIG. 3B, the location closest to the valley bottom of the shaft-side ball rolling groove 4 in the one-side opening 92A (the location closest to the axial center of the screw shaft 2) is defined as the bottommost point 93A. The location farthest from the valley bottom of the shaft-side ball rolling groove 4 (the location away from the axis of the screw shaft 2) in the one-side opening 92A is defined as the highest point 93B. In the one-side opening 92A, the points where the one inner peripheral side boundary 32A and the other inner peripheral side boundary 32B intersect are set so as to deviate from the lowest point 93A and the highest point 93B. The bottom point 93A and the highest point 93B become a portion that strongly collides with the ball 18 each time the ball 18 is scooped up, and is easily destroyed by fatigue. Therefore, in the present embodiment, the durability of the lowest point 93A and the highest point 93B is achieved by positively shifting the positions of the lowest point 93A and the highest point 93B, and the one inner peripheral side boundary 32A and the other inner peripheral side boundary 32B. Suppresses the decrease.

Similarly, the location closest to the valley bottom of the axial ball rolling groove 4 in the other opening 94A is defined as the bottom point 95A, and the location closest to the valley bottom of the axial ball rolling groove 4 in the other opening 94A is defined as the bottom point 95A. When defined as the highest point 95B, the lowest point 95A and the highest point 95B, one inner peripheral side boundary 32A and the other inner peripheral side boundary 32B are positively shifted.

With reference to FIG. 3A, the range from one end to the other end of the ball circulation path 90 will be described by dividing it into a plurality of regions from the viewpoint of functionality. The ball circulation path 90 includes a one-sided scooping region 97A, a one-sided turning region 97B, a transition region 97C, a other-sided turning region 97D, and a other-side scooping region 97E. The one-side scooping region 97A serves as a conduit for scooping the ball 18 from the one-side opening 92A along the spiral direction of the screw shaft 2 and separating the ball 18 from the screw shaft 2 in the radial direction. The one-side direction change region 97B is a conduit for changing the traveling direction of the ball 18 separated from the screw shaft 2 by the one-side scooping region 97A in the axial direction of the screw shaft 2. The transition region 97C serves as a conduit for moving the ball 18 whose direction has been changed by the one-side direction change region 97B in the axial direction (pitch direction) of the screw shaft 2. The other side turning region 97D is a conduit for turning the ball 18 moving in the axial direction of the screw shaft 2 along the transition region 97C in the spiral direction of the screw shaft 2. The other-side scooping region 97E guides (supplies) the ball 18 whose direction is changed by the other-side direction turning region 97D to the shaft-side ball rolling groove 4 (ball rolling path 20) by approaching the screw shaft 2. It becomes a pipeline. When the relative rotation directions of the screw shaft 2 and the nut 8 are reversed, the ball circulation path 90 scoops the ball 18 from the other side scooping area 97E and guides the ball 18 to the one side scooping area 97A.

Therefore, as shown in FIG. 3A, when the ball circulation path 90 is viewed in a plan view from the outside in the radial direction of the screw shaft 2, it becomes an S-shaped curved conduit. As shown in FIG. 3B, when the ball circulation path 90 is viewed sideways from the circumferential direction of the screw shaft 2, it becomes a mountain-shaped curved conduit.

Next, the first component piece 40 will be described in detail with reference to FIG. In the first embodiment, the shapes of the first component piece 40 and the second component piece 70 are completely the same as each other and are the same component. Therefore, here, only the first component piece 40 will be described, and the description of the second component piece 70 will be omitted.

The first circulation groove 50 of the first component piece 40 has a regular semicircle in cross section, and the whole is opened to the outside. Therefore, in the first embodiment, the surface roughness can be made finer and can be set to 6.3 Ra or less by manufacturing and sintering the first component piece 40 by the metal powder injection molding method. Further, the first circulation groove 50 is mechanically surface-treated. Specifically, for example, the surface roughness can be made finer by performing cutting, peening, barrel polishing, etc. on the first circulation groove 50, and the surface roughness can be reduced to 3.2 Ra or less, preferably 2.0 Ra or less. can. Further, the surface hardness of the first circulation groove 50 by Micro Vickers is set to 100 to 300 HV, preferably 135 to 225 HV. Further, when cutting is performed, the first circulation groove 50 is molded by a metal powder injection molding method so that the first circulation groove 50 has a yield of 0.5 mm or less, and the allowance of the first circulation groove 50 is cut by cutting. By finishing, the surface texture is improved while increasing the material yield. The one-sided edge of the first circulation groove 50 coincides with the one inner peripheral boundary 32A, and the other edge coincides with the other inner peripheral boundary 32B.

The first component piece 40 has a first contact surface 42 continuous from the edge of the first circulation groove 50. The first contact surface 42 comes into contact with the second contact surface 72 (see FIG. 5) of the second component piece 70. In detail, the first contact surface 42 is continuous from one side first contact surface 42A continuous from one side edge (one inner peripheral side boundary 32A) and continuous from the other side edge (the other inner peripheral side boundary 32B). It has a first contact surface 42B on the other side.

As shown in the partially enlarged regions C1 and C2 of FIG. 4C, the angle formed by the first circulation groove 50 and the first contact surface 42 continuous with the first circulation groove 50 at the edge of the first circulation groove 50 is , Obtuse or acute angle is set at least in a part of the groove longitudinal direction. Specifically, in the partially expanded region C1, the angle formed by the first circulation groove 50 and the first contact surface 42 is set to an acute angle, and in the partially expanded region C2, the first circulation groove 50 and the first contact surface 42 are formed. The angle of formation is set to an acute angle. In this way, the contact width of the first contact surface 42 and the contact width of the first contact surface 42 and the like in the partially enlarged areas C1 and C2 where the member tends to be thin (particularly in the one-side scooping area 97A and the multi-side scooping area 97E). The area can be set large.

Further, as shown in the partially enlarged regions C1 and C2, the edges (inner peripheral side boundary 32) of the first circulation groove 50 and the first contact surface 42 are curved (rounded), so that they are affected by an impact. It is possible to suppress the loss of the edge.

When the angle formed by the first circulation groove 50 and the first contact surface 42 is an acute angle, it is preferably set to 70 degrees or less, preferably 60 degrees or less, and more preferably 45 degrees or less in at least a part of the angle. do. On the contrary, when the angle formed by the first circulation groove 50 and the first contact surface 42 is an obtuse angle, it is preferably set to 110 degrees or more, preferably 120 degrees or more, and more preferably 135 degrees or more in at least a part of the angle. And.

On the first contact surface 42, a coupling pin 44A, which is a kind of protrusion, is provided in the vicinity of the one-side opening 92A. Further, a concave coupling hole 44B is provided in the vicinity of the other side opening 94A in 42. The size of the coupling pin 44A is set to be slightly larger than the size of the coupling hole 44B. As shown in FIG. 5, the coupling pin 44A of the first component piece 40 is press-fitted into the coupling hole 74B of the second component piece 70 having the same shape. As a result, the first component piece 40 and the second component piece 70 are connected.

The central axis (insertion direction) of the coupling pin 44A is erected so as to be non-perpendicular (inclined) with respect to the plane of the first contact surface 42 continuous around the base end thereof. In this way, the first contact surface 42 and the second contact surface 72 can be tilted with respect to the coupling direction of the coupling pin 44A and the coupling hole 74B (see the arrow in FIG. 5). The contact surface 42 and the second contact surface 72 can be brought into contact with each other while being rubbed against each other.

Returning to FIG. 4, a positioning pin 45A, which is a kind of protrusion, is provided in the vicinity of the one-side opening 92A on the first contact surface 42. Further, a concave positioning hole 45B is provided in the vicinity of the other side opening 94A on the first contact surface 42. The positioning pin 45A has a conical or partial conical shape, and the positioning hole 45B has a mortar shape. As shown in FIG. 5, when the positioning pin 45A of the first component piece 40 is inserted into the positioning hole 75B of the second component piece 70 having the same shape, it is autonomously centered by the tapered engagement. As a result, the relative positions of the first component piece 40 and the second component piece 70 are determined. The length of the positioning pin 45A is longer than that of the coupling pin 44A. In this way, when assembling the first component piece 40 and the second component piece 70, the positioning pin 45A and the positioning hole 75B are preferentially engaged and centered, and then the coupling pin 44A and the coupling hole 74B are performed. Fits in a press-fitted state.

The central axis (insertion direction) of the positioning pin 45A is erected so as to be non-perpendicular (inclined) with respect to the plane of the first contact surface 42 continuous around the base end thereof. Further, the positioning pin 45A and the coupling pin 44A are parallel to each other.

According to the ball circulation component 30 of the first embodiment, the ball circulation component 30 is divided into a first component piece 40 and a second component piece 70. Along with this, the ball circulation path 90 is divided into two by the first circulation groove 50 and the second circulation groove 80 so as to have an equal volume to each other. As a result, advanced quality control can be realized by checking the states of the first circulation groove 50 and the second circulation groove 80 before combining the first component piece 40 and the second component piece 70. Further, it is possible to perform machining such as peening and mirror polishing over the entire first circulation groove 50 and the second circulation groove 80, so that the rolling resistance of the ball 18 in the ball circulation path 90 can be reduced and the durability can be reduced. Can be improved.

Further, in the ball circulation path 90, the strength of the ball circulation path 30 does not decrease by preventing the division boundary from matching the bottom point 93A and the highest point 93B in the one-side opening 92A that scoops up the ball 18. .. As a result, a high quality and high strength ball circulation component 30 can be obtained by using the metal powder injection molding method.

Further, the contact area of the first contact surface 42 can be expanded by making the angle formed by the first contact surface 42 of the first component piece 40 and the first circulation groove 50 at an acute angle or an obtuse angle at least in part. In particular, the contact width of the first contact surface 42 can be made as large as possible in a thin portion, for example, in the vicinity of the one-side opening 92A. It is also possible to improve workability when assembling the first component piece 40 and the second component piece 70.

Further, in the present embodiment, the phase of the pair of points of the one inner peripheral side boundary 32A and the other inner peripheral side boundary 32B (that is, the phase of the edges of the first circulation groove 50 and the second circulation groove 80) is the central axis 90A. When the bending direction of the above is used as the reference phase, the phase does not change (phase transition) even if it is moved along the central axis 90A. In this way, the first circulation groove 50 and the second circulation groove 80 are unlikely to be in a so-called undercut state. Therefore, when the first component piece 40 and the second component piece 70 are molded by the metal powder injection molding method, gold is used. It can be easily released from the mold.

Next, with reference to FIG. 7, a modified example of the ball circulation component 30 of the first embodiment is shown. Here, a part of the ball circulation path 90 is not completely tubular (tubular in a closed state), but is in a partially cylindrical state in which a part of the cylinder is missing. As shown in FIG. 7C, the first component piece 40 is formed with a first open recess 43 that is continuous from the second contact surface 42 and is recessed in the contact direction. Further, the second component piece 70 is formed with a second open recess 73 that is continuous from the second contact surface 72 and is recessed in the contact direction. Since the first open recess 43 and the second open recess 73 are portions that do not come into contact with the mating member, the slit (through hole) 98 is formed by the first open recess 43 and the second open recess 73 when assembled. It is formed. As a result, the inner peripheral surface of the ball circulation path 90 is exposed to the outside through the slit (through hole) 98. Here, a slit (through hole) 98 is formed on the screw shaft 2 side of the ball circulation path 90.

The direction in which the slit (through hole) 98 is formed is not limited to FIG. As in the modified example shown in FIG. 8, a first open recess 43 and a second open recess 73 are formed on the side of the ball circulation path 90 opposite to the screw shaft 2, and a slit (through hole) 98 is formed by these. May be good (see Fig. 7 (A))

Next, the ball screw device 101 in which the ball circulation component 130 according to the second embodiment of the present invention is incorporated is shown with reference to FIGS. 9 and 9. Here, the parts different from the ball circulation component 30 and the ball screw device 1 of the first embodiment will be mainly described, and for the same or similar parts / members, the last two digits of the reference numerals shall be matched with each other. Therefore, the description is omitted.

The ball screw device 101 is of a return tube type, and has a screw shaft 102 as a shaft body, a nut 108 as a relative moving body, a plurality of balls 118 rolling between the screw shaft 102 and the nut 108, and a nut 108. It has a ball circulation component 130 (return tube) to be assembled.

A component accommodating space 112 is formed in the nut 108. The component accommodating space 112 is a pair of through holes, and the ball circulation component 130 is fixed to the outer periphery of the nut 108 with both ends of the ball circulation component 130 inserted into the through holes. As a result, both ends of the ball circulation path 190 can face the outer peripheral surface (ball rolling path 120) of the screw shaft 102. The ball circulation component 130 is circulated by returning the balls 118 by a plurality of leads (here, about 4 leads) of the screw shaft 102 by the U-shaped ball circulation path 190.

FIG. 10A shows an enlarged ball circulation component 130. The ball circulation component 130 includes a first component piece 140 and a second component piece 170. These component pieces are formed by a metal powder injection molding method, and by combining the first component piece 140 and the second component piece 170 (see FIG. 11), a tubular ball circulation path 190 is formed inside. The first component piece 140 and the second component piece 170 have the same shape as each other.

The outer peripheral surface of the ball circulation component 130 has an outer peripheral side boundary 131 that separates the first component piece 140 and the second component piece 170. As can be seen from the outer peripheral side boundary 131, the vicinity of both ends of the ball circulation path 190 is not divided into the first component piece 140 and the second component piece 170. Specifically, the entire pipe in the vicinity of the opening 192A on one side of the ball circulation path 190 is integrated with the first component piece 140 side. Further, the entire pipe in the vicinity of the opening 194A on the other side of the ball circulation path 190 is integrated with the second component piece 170 side. That is, in the ball circulation path 190, the one-side scooping region 197A and the other-side scooping region 197E are each in a non-divided state, and the inner peripheral side boundary 132 is not formed. The distance M of the undivided region near both ends of the ball lubrication path 190 is preferably one-third or less, preferably one-fourth or less of the total length of the ball lubrication path 190. By shortening the length M of the non-divided region, the entire inner peripheral surface thereof can be processed by blasting or the like.

On the other hand, the one-side turning region 197B, the transition region 197C, and the other-side turning region 197D excluding these are divided (half-divided) by the first component piece 140 and the second component piece 170. As a result, as shown in the second component piece 170 of FIG. 10B, the second circulation groove 180 in the half-split state is formed. Both edges of the second circulation groove 180 serve as the inner peripheral side boundary 132.

Incidentally, the one-side opening 192A and the other-side opening 194A become a portion that strongly collides with the ball 118 each time the ball 118 is scooped up, so that the ball 118 is easily destroyed by fatigue. Therefore, in the present embodiment, the durability is improved by not forming the inner peripheral side boundary 132 in the one-side opening 192A and the other-side opening 194A. As shown in FIG. 11, when the first component piece 140 and the second component piece 170 are combined, the one-side opening 192A of the first component piece 140 is located at one end of the ball circulation path 190, and at the same time, the second component piece The other side opening 194A of 170 may be located at multiple ends of the ball circulation path 190.

Next, the ball screw device 201 in which the ball circulation component 230 according to the third embodiment of the present invention is incorporated is shown with reference to FIGS. 12 and later. Here, the parts different from the ball circulation component 30 and the ball screw device 1 of the first embodiment will be mainly described, and for the same or similar parts / members, the last two digits of the reference numerals shall be matched with each other. Therefore, the description is omitted.

The ball screw device 201 has a guide plate system, and has a screw shaft 202 as a shaft body, a nut 208 as a relative moving body, and a plurality of balls 218 and nut 208 that roll between the screw shaft 202 and the nut 208. It has a pair of ball circulation parts 130 (deflectors) to be assembled.

A pair of component accommodating spaces 212 are formed in the nut 208. Each component accommodating space 212 is a through hole, and the ball circulation component 230 is inserted and fixed into the through hole. An intermediate ball circulation path 291 is formed between the pair of ball circulation components 130 in the nut 208, and both ends of the intermediate ball circulation path 291 are connected to the ball circulation path 290 of the pair of ball circulation components 230. Through this ball circulation path, the balls 218 are returned and circulated by a plurality of leads of the screw shaft 202 (here, about 4 leads).

FIG. 13 shows the ball circulation component 230 in an enlarged manner. The ball circulation component 230 includes a first component piece 240 and a second component piece 270. These component pieces are formed by a metal powder injection molding method, and by combining the first component piece 240 and the second component piece 270 (see FIG. 15), a tubular ball circulation path 290 is formed inside. The first component piece 240 and the second component piece 270 have different shapes.

The outer peripheral surface of the ball circulation component 230 has an outer peripheral side boundary 231 that separates the first component piece 240 and the second component piece 270. As can be seen from the outer peripheral side boundary 231, the entire pipe in the vicinity of the one-side opening 292A of the ball circulation path 290 is integrated with the first component piece 240 side. The other side opening 294A of the ball circulation path 290 is divided by a first component piece 240 and a second component piece 270.

The ball circulation path 290 has a one-sided scooping region 297A and a one-sided turning region 297B from the one-sided opening 292A to the other-sided opening 294A. The one-sided scooping region 297A in the vicinity of the one-sided opening 292A approaches the ball rolling path 220 (see FIG. 12A). The one-side turning region 297B turns the ball circulation path 290 at an angle of about 90 degrees. The other side opening 294A is continuous with the intermediate ball circulation path 291 (see FIG. 12A).

The one-side turning region 297B is divided (half-split) by the first component piece 240 and the second component piece 270. As a result, the first circulation groove 250 is formed in the first component piece 240 of FIG. 14 (A), and the second circulation groove 280 is formed in the second component piece 270 of FIG. 14 (B). By the way, the one-side opening 292A becomes a portion that strongly collides with the ball 218 each time the ball 218 is scooped up, so that it is easily fractured by fatigue. Therefore, in the present embodiment, the durability is improved by not forming the boundary that divides the one-side opening 292A.

A coupling hole 244B and a positioning hole 245B are formed on the first contact surface 242 of the first component piece 240. On the other hand, the coupling pin 274A and the positioning pin 275A are provided on the second contact surface 272 of the second component piece 270. As shown in FIG. 15, when the first component piece 240 and the second component piece 270 are combined, the coupling pin 274A of the second component piece 270 is press-fitted into the coupling hole 244B of the first component piece 240. Fit. Prior to this fitting, the positioning pin 275A of the second component piece 270 is inserted into the positioning hole 245B of the first component piece 240 to autonomously center the first component piece 240 and the second component piece 270. ..

Next, a modified example of the ball circulation component 230 according to the third embodiment will be described with reference to FIGS. 16 to 18. FIG. 16 shows the ball circulation component 230 in an enlarged manner. As can be seen from the outer peripheral side boundary 231, the entire ball circulation path 290 is divided by the first component piece 240 and the second component piece 270.

As shown in FIG. 17A, the inner peripheral side boundary 232 that separates the first component piece 240 and the second component piece 270 has, in detail, one inner peripheral side boundary 232A and the other inner peripheral side boundary 232B. .. In a cross section (perfect circle) orthogonal to the central axis of the ball circulation path 90, a pair of points where one inner peripheral side boundary 232A and the other inner peripheral side boundary 232B intersect are set so as to always maintain a phase difference of 180 degrees from each other. Will be done. Further, the phase of the pair of points of the one inner peripheral side boundary 232A and the other inner peripheral side boundary 232B in this cross section (perfect circle) is set to this reference phase when the bending direction (bending direction) of the central axis is used as the reference phase. On the other hand, it is set to a state where the phase does not always change (phase transition). In other words, one inner peripheral boundary 232A and the other inner peripheral boundary 232B have reference phases in the bending direction (bending direction) of the central axis even if they move along the central axis (no matter which cross section is cut). It becomes a state where it does not turn (a state where the phase is fixed).

Returning to FIG. 16C, the place closest to the valley bottom of the shaft-side ball rolling groove in the one-side opening 292A (the place closest to the axis of the screw shaft 202) is defined as the bottom point 293A, and the valley bottom is defined as the bottom point. The place farthest from (the place away from the axis of the screw shaft 202) is defined as the highest point 293B. In the one-side opening 292A, the points intersecting the one inner peripheral side boundary 232A and the other inner peripheral side boundary 232B are set so as to deviate from the lowest point 293A and the highest point 293B. As a result, it is possible to prevent the durability of the lowest point 293A and the highest point 293B from being lowered.

As shown in the partially enlarged region A1 of FIG. 17 (A), at the edge of the first circulation groove 250, the angle formed by the first circulation groove 250 and the first contact surface 242 continuous with the first circulation groove 250 is a groove. It is set to an obtuse or acute angle at least in part of the longitudinal direction. Specifically, in the partially enlarged region A1, the angle formed by the first circulation groove 250 and the first contact surface 242 is set to an acute angle. In this way, the contact width and area of the first contact surface 242 can be set large in the portion where the member tends to be thin (particularly, the one-side scooping area 297A). A coupling pin 244A and a positioning pin 245A are formed on the first component piece 240. On the other hand, the second component piece 270 is provided with a coupling hole 274B and a positioning hole 275B. As shown in FIG. 18, when the first component piece 240 and the second component piece 270 are combined, the coupling pin 244A of the first component piece 240 is press-fitted into the coupling hole 274B of the second component piece 270. Fit. Prior to this fitting, the positioning pin 245A of the first component piece 240 is inserted into the positioning hole 275B of the second component piece 270 to autonomously center the first component piece 240 and the second component piece 270.

The ball circulation component of the present invention is not limited to the one illustrated in the above embodiment, and can be appropriately modified without departing from the spirit of the present invention.

1 Ball screw device 2 Screw shaft 4 Shaft side ball rolling groove 8 Nut 10 Moving body side ball rolling groove 12 Parts storage space 18 Ball 20 Ball rolling path 30 Ball circulation parts 31 Outer peripheral side boundary 32 Inner peripheral side boundary 40 First Part piece 42 First contact surface 43 First open recess 44A Coupling pin 44B Coupling hole 45A Positioning pin 50 First circulation groove 70 Second part piece 72 Second contact surface 73 Second open recess 74B Coupling hole 75B Positioning hole 80 Second circulation groove 90 Ball circulation path 90A Central axis

Claims (12)

A ball-type moving mechanism that allows the shaft body and the relative moving body to move relative to each other by rolling a plurality of balls in the gap between the shaft body and the relative moving body arranged with a gap with respect to the shaft body. A ball circulation component that is installed in the relative moving body and forms at least a part of a ball circulation path that circulates the ball between one end and the other end of the ball rolling path formed in the gap.
A first component piece formed by a metal powder injection molding method and having a first circulation groove defining the ball circulation path,
A second component piece formed by a metal powder injection molding method and having a second circulation groove defining the ball circulation path.
By combining the first component piece and the second component piece in a posture in which the first circulation groove and the second circulation groove face each other, the ball circulation path is formed by the first circulation groove and the second circulation groove. It is,
The first component piece has a first contact surface continuous from the edge of the first circulation groove.
The second component piece has a second contact surface that is continuous from the edge of the second circulation groove and is in contact with the first contact surface.
A coupling projection is provided on either one of the first contact surface and the second contact surface, and a coupling recess is provided on either one of the first contact surface and the second contact surface. It is provided,
By fitting the coupling protrusion and the coupling recess by press fitting, the first component piece and the second component piece are bonded to each other.
The central axis of the coupling projection is non-vertical with respect to either one of the first contact surface and the second contact surface continuous around the base end of the coupling projection.
Ball circulation parts. A cone-shaped positioning projection is provided on either one of the first contact surface and the second contact surface, and the first contact surface and the second contact surface are provided on either one of the first contact surface and the second contact surface. A mortar-shaped positioning recess is provided,
By engaging the positioning protrusion with the positioning recess, the relative positions of the first component piece and the second component piece are determined .
The central axis of the positioning protrusion is not perpendicular to either one of the first contact surface and the second contact surface continuous around the base end of the positioning protrusion.
The ball circulation component according to claim 1. The first component piece has a region where the angle formed by the first circulation groove and the first contact surface is an obtuse angle at least a part of the first contact surface continuous from the edge.
The second component piece has a region where the angle formed by the second circulation groove and the second contact surface is an acute angle at least a part of the second contact surface continuous from the edge.
The obtuse-angled region of the first component piece and the acute-angled region of the second component piece are in contact with each other.
The ball circulation component according to claim 1 or 2. The surface roughness of the first circulation groove and the second circulation groove is set to 6.3 Ra or less.
The ball circulation component according to any one of claims 1 to 3. The surfaces of the first circulation groove and the second circulation groove are machined.
The ball circulation component according to any one of claims 1 to 4. One end of the ball circulation path is provided with a one-sided opening that faces the ball rolling path and scoops up the ball from the ball rolling path.
The one-sided opening is characterized in that the lowest point closest to the valley bottom of the ball rolling path and the boundary between the first component piece and the second component piece do not match.
The ball circulation component according to any one of claims 1 to 5. A boundary between the first component piece and the second component piece is formed at a position different from the bottom point of the one-side opening.
The ball circulation component according to claim 6. One end of the ball circulation path is provided with an opening on one side facing the ball rolling path and scooping up the ball from the ball rolling path.
The one-sided opening is characterized in that the highest point farthest from the valley bottom of the ball rolling path and the boundary between the first component piece and the second component piece do not match.
The ball circulation component according to any one of claims 1 to 7. A boundary between the first component piece and the second component piece is formed at a position different from the highest point in the one-side opening.
The ball circulation component according to claim 8. One end of the ball circulation path is provided with an opening on one side facing the ball rolling path and scooping up the ball from the ball rolling path.
The one-side opening is characterized in that a boundary between the first component piece and the second component piece is not formed.
The ball circulation component according to any one of claims 1 to 5. The edge of the first circulation groove and the first contact surface is curved.
The ball circulation component according to any one of claims 1 to 10. The edge of the first circulation groove is characterized in that when it transitions in the axial direction of the central axis of the ball circulation path, the phase does not change with the bending direction of the central axis as a reference phase.
The ball circulation component according to any one of claims 1 to 11.

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