WO2012066693A1 - ボールねじ - Google Patents
ボールねじ Download PDFInfo
- Publication number
- WO2012066693A1 WO2012066693A1 PCT/JP2011/001973 JP2011001973W WO2012066693A1 WO 2012066693 A1 WO2012066693 A1 WO 2012066693A1 JP 2011001973 W JP2011001973 W JP 2011001973W WO 2012066693 A1 WO2012066693 A1 WO 2012066693A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- ball
- groove
- nut
- screw
- ball circulation
- Prior art date
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
- F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
- F16H25/20—Screw mechanisms
- F16H25/24—Elements essential to such mechanisms, e.g. screws, nuts
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
- F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
- F16H25/20—Screw mechanisms
- F16H25/22—Screw mechanisms with balls, rollers, or similar members between the co-operating parts; Elements essential to the use of such members
- F16H25/2204—Screw mechanisms with balls, rollers, or similar members between the co-operating parts; Elements essential to the use of such members with balls
- F16H25/2214—Screw mechanisms with balls, rollers, or similar members between the co-operating parts; Elements essential to the use of such members with balls with elements for guiding the circulating balls
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
- F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
- F16H25/20—Screw mechanisms
- F16H25/22—Screw mechanisms with balls, rollers, or similar members between the co-operating parts; Elements essential to the use of such members
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
- F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
- F16H25/20—Screw mechanisms
- F16H25/22—Screw mechanisms with balls, rollers, or similar members between the co-operating parts; Elements essential to the use of such members
- F16H25/2204—Screw mechanisms with balls, rollers, or similar members between the co-operating parts; Elements essential to the use of such members with balls
- F16H25/2214—Screw mechanisms with balls, rollers, or similar members between the co-operating parts; Elements essential to the use of such members with balls with elements for guiding the circulating balls
- F16H25/2223—Cross over deflectors between adjacent thread turns, e.g. S-form deflectors connecting neighbouring threads
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T74/00—Machine element or mechanism
- Y10T74/19—Gearing
- Y10T74/19642—Directly cooperating gears
- Y10T74/19698—Spiral
- Y10T74/19702—Screw and nut
- Y10T74/19744—Rolling element engaging thread
- Y10T74/19749—Recirculating rolling elements
- Y10T74/19767—Return path geometry
- Y10T74/19772—Rolling element deflector
Definitions
- the present invention relates to a ball screw having a groove-shaped ball return path (ball circulation groove).
- the ball screw is composed of a screw shaft having a helical thread groove (hereinafter sometimes referred to as a spiral groove) on the outer peripheral surface, a nut having a screw groove facing the screw groove of the screw shaft on the inner peripheral surface, A plurality of balls slidably loaded in a spiral ball rolling path (hereinafter sometimes referred to as a track) formed by a thread groove, and the balls are circulated from the end point of the ball rolling path to the start point. And a ball return path (hereinafter also referred to as a ball circulation groove or a ball circulation path). Then, when the nut and the screw shaft that are screwed to the screw shaft through the ball are relatively rotated, the screw shaft and the nut are relatively moved in the axial direction through the rolling of the ball. .
- Such a ball screw is used not only for a general industrial machine positioning device but also for an electric actuator mounted on a vehicle such as an automobile, a two-wheeled vehicle or a ship.
- the circulation method of the ball using the ball return path includes a circulation tube method and a top method.
- the top method the top having a recess (groove-shaped ball return path) forming the ball return path is inserted into the nut. It fits in the through hole.
- a groove-shaped ball return path (often referred to as a “ball circulation groove”) is formed directly on the inner peripheral surface of the nut, it is possible to reduce the time and cost of assembly and reduce the ball The improvement of the reliability of circulation can be expected.
- Patent Document 1 As a method of manufacturing a ball screw in which a ball circulation groove is directly formed on the inner peripheral surface of a nut, a circulation groove (ball circulation groove) is directly formed on the inner peripheral surface of a nut material by plastic working. Further, it is described that a female thread groove (ball rolling groove) is cut. Patent Document 2 describes that an annular ball circulation portion coaxial with the nut is provided at one end in the axial direction of the nut, and a ball circulation groove is provided in the ball circulation portion.
- Patent Document 3 describes that a cross-sectional shape having a groove bottom and a pair of side surfaces orthogonal to the ball traveling direction of the circulation groove (ball circulation groove) has a shape in which the side surface expands in a direction away from the groove bottom.
- the gap between the circulation groove and the ball can be set small to suppress the meandering of the ball and the level difference between the circulation groove and the screw shaft, thereby suppressing abnormal noise and vibration and ensuring smooth operation. It is described that it can.
- Patent Document 4 a ball circulation groove is provided on a screw shaft, and the entire ball circulation groove is gently wavy in the radial direction, and the connecting portion of the screw shaft with the screw groove does not have an extremely sharp edge. It is described that it is shaped. Thereby, the ball can smoothly enter and exit between the thread groove of the screw shaft and the ball circulation groove.
- An object of the present invention is to further improve the durability, ball circulation performance, and processing performance of a ball screw having a groove-shaped ball return path (ball circulation groove).
- the ball screw according to the first aspect of the present invention includes a screw shaft having a helical screw groove on the outer peripheral surface, a nut having a screw groove facing the screw groove of the screw shaft on the inner peripheral surface, A plurality of balls slidably loaded in a spiral ball rolling path formed by both screw grooves, and a ball circulation groove for circulating the ball from the end point of the ball rolling path to the start point, At least a part of a corner portion formed by both side surfaces of the ball circulation groove and surfaces extending continuously in the axial direction from the side surfaces is formed to be round.
- the ball screw according to the second aspect of the present invention is the ball screw according to the first aspect, wherein the nut comprises a concave groove formed on a part of an inner peripheral surface of the nut, and the ball is formed of a concave groove.
- a circulation groove is formed, and the screw groove is formed on the inner peripheral surface of the nut so as to be connected to the end of the ball circulation groove.
- the ball screw according to the third aspect of the present invention is provided with a lubricant reservoir capable of retaining a lubricant in the ball according to the second aspect, and the lubricant reservoir is formed on the inner surface of the concave groove. It consists of the recessed part which makes a part concave.
- the ball screw which concerns on the 4th aspect of this invention is a ball
- channel is between the both ends which are a connection part with the said ball rolling path, and the said both ends.
- the area of the cross section of the lubricant reservoir, which is formed by an intermediate portion and cut along a plane perpendicular to the longitudinal direction of the ball circulation groove, is larger in the portion adjacent to the intermediate portion than in the portion adjacent to the end portion. It is characterized by that.
- the ball screw according to the fifth aspect of the present invention is the ball according to the third aspect, wherein the ball circulation groove is curved and arranged on the radially outer side of the curve of the ball circulation groove.
- the lubricant reservoir disposed on the radially inner side of the curvature of the ball circulation groove has a larger cross-sectional area cut by a plane perpendicular to the longitudinal direction of the ball circulation groove than the lubricant reservoir.
- the ball screw according to the sixth aspect of the present invention is the ball according to the third aspect, wherein the concave groove constituting the ball circulation groove and the concave part constituting the lubricant reservoir are formed simultaneously. It is characterized by being. Furthermore, the ball screw according to the seventh aspect of the present invention is characterized in that, in the ball according to the second aspect, the arithmetic mean roughness Ra 2 of the surface of the ball circulation groove is more than 0 ⁇ m and 1.6 ⁇ m or less. To do.
- a ball screw according to an eighth aspect of the present invention is the ball according to the seventh aspect, wherein the ball screw according to the seventh aspect is inserted into a cylindrical nut material and moves along the axial direction thereof; A convex portion corresponding to the ball circulation groove is formed between the cam driver, and the convex portion moves in a radial direction of the nut by the movement of the cam driver, and the convex portion
- the arithmetic average roughness Ra 1 of the surface is 0.01 ⁇ m or more and 0.2 ⁇ m or less
- the ball circulation groove is formed on the inner peripheral surface of the nut material.
- the ball circulation groove is constituted by a concave groove formed by recessing a part of the inner peripheral surface of the nut.
- the surface hardness of the thread groove of the nut is HRC 58 or more and 62 or less
- the surface hardness of both ends of the ball circulation groove connected to the ball rolling path is HRC 58 or more and 62 or less.
- the surface hardness of the intermediate portion between the both end portions of the groove is HV550 or less.
- the ball screw according to an eleventh aspect of the present invention is the ball according to the second aspect, wherein the nut is at least one of brushing and blasting at a boundary portion between the ball circulation groove and the ball rolling path. And is formed by removing burrs.
- the ball screw according to the twelfth aspect of the present invention is characterized in that, in the ball according to the second aspect, the following three conditions A, B, and C are satisfied.
- Condition A The ball circulation groove is formed by a groove formed by recessing a part of the inner peripheral surface of the nut.
- Condition B The ball circulation groove includes both end portions that are connection portions with the ball rolling path, an intermediate portion disposed between the both end portions, and a curved portion that connects the end portion and the intermediate portion. And is substantially S-shaped.
- the edge portion of the curved portion of the edge portion of the concave groove is curved, and the edge portion on the radially outer side of the curve has a shape in which a plurality of arcs having different curvature radii are smoothly continuous. Is formed.
- the ball screw according to a thirteenth aspect of the present invention is the ball according to the second aspect, wherein the ball circulation groove is between both end portions that are connected to the ball rolling path and between the both end portions. An intermediate portion disposed, and the groove width of the intermediate portion is narrower than the groove width of the end portion.
- the ball screw according to the fourteenth aspect of the present invention is characterized in that, in the ball according to the second aspect, the following three conditions D, E, and F are satisfied.
- Condition D The ball circulation groove is constituted by a groove formed by recessing a part of the inner peripheral surface of the nut.
- Condition E The ball circulation groove is composed of both end portions which are connecting portions with the ball rolling path, and two curved portions which are arranged between the both end portions and bend in opposite directions, and are substantially S-shaped. I am doing.
- the edges of the two curved parts are curved, and the radially outer edge of the curve has a shape in which a plurality of arcs having different curvature radii are smoothly continuous. Is formed. Furthermore, the ball screw according to the fifteenth aspect of the present invention is characterized in that, in the ball according to the second aspect, the following three conditions G, H, and I are satisfied.
- the ball circulation groove is formed by a groove formed by recessing a part of the inner peripheral surface of the nut.
- Condition H The ball circulation groove is composed of both end portions that are connected to the ball rolling path, and two curved portions that are arranged between the both end portions and are curved in opposite directions. I am doing.
- the ball screw according to the sixteenth aspect of the present invention is the ball according to the second aspect, wherein the ball circulation groove is formed by a concave groove formed by recessing a part of the inner peripheral surface of the nut.
- the ball circulation groove in the longitudinal direction has a substantially V-shaped cross-section when cut along a plane orthogonal to the longitudinal direction.
- the ball screw according to a seventeenth aspect of the present invention is the ball according to the sixteenth aspect, wherein the ball circulation groove is between both end portions that are connected to the ball rolling path and between the both end portions.
- An intermediate portion is formed, and at least one of the intermediate portion and the end portion has a substantially V-shaped cross section when cut along a plane perpendicular to the longitudinal direction of the ball circulation groove.
- the ball screw according to the eighteenth aspect of the present invention is characterized in that, in the ball according to the sixteenth aspect, a lubricant reservoir is provided at the bottom of the concave groove constituting the ball circulation groove.
- the ball screw of the present invention has good durability, ball circulation performance, and processing performance.
- FIG. 2 is a cross-sectional view taken along the line AA in FIG.
- FIG. 5 is a cross-sectional view taken along line AA in FIG. 4.
- FIG. 4 is a perspective view which shows the component of a metal mold
- the top view (a) which shows the fitting state of the cam slider and cam driver which comprise the metal mold
- the perspective view (b) which shows a cam slider
- (a) is a perspective view showing the state of cutting of a nut material
- (b) is (a). It is the figure which looked at the nut raw material and cutting tool which are shown to the arrow VA direction.
- FIG. 34 is a BB cross-sectional view of the concave groove of FIG. 33. It is the enlarged view which looked at the ditch
- FIG. 36 is a cross-sectional view taken along the line CC of FIG. FIG. 36 is a DD cross-sectional view of the concave groove and the concave portion of FIG. 35. It is the enlarged view which looked at the ditch
- the ball screw of the first example of the first embodiment includes a screw shaft 201, a nut 202, a ball 203, and a piece 204.
- a spiral groove 201 a is formed on the outer peripheral surface of the screw shaft 201.
- a spiral groove 202 a is formed on the inner peripheral surface of the nut 202.
- a top 204 is fitted in a through hole 202b that penetrates the nut 202 in the radial direction.
- the ball 203 is disposed between the tracks formed by the spiral groove 202 a of the nut 202 and the spiral groove 201 a of the screw shaft 201.
- a ball circulation groove 241 for returning the ball 203 from the end point of the trajectory to the start point is formed on the top 204.
- the ball circulation groove 241 formed on the top 204 has a groove bottom 241a and a pair of side surfaces 241b continuous to the groove bottom 241a. Corner portions 241c between both side surfaces 241b of the ball circulation groove 241 and surfaces 242 extending in the axial direction continuous to the respective side surfaces 241b are formed in a round shape.
- the ball circulation groove 241 is formed directly on the inner peripheral surface 202d of the nut 202, and the through hole 202b as shown in FIG. Is not formed, and the frame 204 is not provided.
- the ball circulation groove 241 formed on the inner peripheral surface 202d of the nut 202 has a groove bottom 241a and a pair of side surfaces 241b continuous to the groove bottom 241a. Corners 241c between both side surfaces 241b of the ball circulation groove 241 and axially extending surfaces (inner peripheral surfaces of the nuts 202) 202d continuous with the respective side surfaces 241b are formed in a round shape.
- the corner portion 241c of the ball circulation groove 241 is formed in a round shape, the ball 203 is circulated when the ball 203 circulates compared with the case where the ball 203 is not formed in a round shape. Scratches and dents are unlikely to occur on the surface, and the corners 241c of the ball circulation groove 241 are not easily chipped. Therefore, durability is improved. Further, since the ball 203 traveling in the ball circulation groove 241 can move smoothly even when it exceeds the outer peripheral surface (land portion) 201b of the screw shaft 1, the ball circulation performance is improved. Further, since the corner portion 241c of the ball circulation groove 241 is formed in a round shape, almost no burr is generated in the corner portion 241c. Therefore, since the post-deburring process can be omitted, the processing performance is improved.
- a nut 202 in which a ball circulation groove 241 with a round corner 241 c is directly formed is shown on the inner peripheral surface of a cylindrical blank made of a nut material, for example, as shown in FIG.
- the ball rolling groove can be formed by cutting so as to connect both ends of the ball circulation groove.
- protrusions 252 and 253 corresponding to the ball circulation grooves 241 are formed on the base surface 251.
- the first protrusion 252 forms the groove bottom 241a and the side surface 241b of the ball circulation groove 241, and the second protrusion 253 forms the roundness of the corner portion 241c.
- the ball circulation groove 241 is connected to the spiral groove 202a of the nut 202 as shown in FIG.
- the ball 203 that has entered the ball circulation groove 241 from the spiral groove 202 a hits the side surface 241 b of the ball circulation groove 241 and is in the direction of the arrow.
- the ball 203 to which this force is applied is over the outer peripheral surface (land portion) 201b of the screw shaft 201 at the central portion (B portion) of the ball circulation groove 241 as shown in the left diagram of FIG. Move to the groove 202a. Therefore, it is necessary to set the degree of roundness of the corner portion 241c within a range in which a force that allows the ball 203 to smoothly get over the land portion 201b of the screw shaft 201 is applied.
- an annular ball circulation portion coaxial with the nut is provided at one axial end of the nut, and the ball circulation groove is provided in the ball circulation portion.
- a cross-sectional shape having a groove bottom and a pair of side surfaces orthogonal to the ball traveling direction of the circulation groove (ball circulation groove) has a shape in which the side surface expands in a direction away from the groove bottom.
- the second embodiment relates to a ball screw.
- the ball screw is a spiral ball rolling path formed by a screw shaft having a helical thread groove on the outer peripheral surface, a nut having a screw groove facing the screw groove of the screw shaft on the inner peripheral surface, and both screw grooves. And a plurality of balls loaded in a rollable manner. Then, when the nut and the screw shaft that are screwed to the screw shaft through the ball are relatively rotated, the screw shaft and the nut are relatively moved in the axial direction through the rolling of the ball. .
- Such a ball screw is provided with a ball circulation path that forms an endless ball path by communicating the start point and end point of the ball rolling path. That is, the ball moves around the screw shaft while moving in the ball rolling path and reaches the end point of the ball rolling path. The ball is scooped up from one end of the ball circulation path and passes through the ball circulation path. The ball is returned to the starting point of the ball rolling path from the other end of the circulation path.
- the screw shaft and the nut can continuously move relative to each other.
- the shape of the ball circulation path in such a ball screw for example, as disclosed in Patent Document 3, the cross-sectional shape when cut along a plane perpendicular to the longitudinal direction of the ball circulation path is substantially U-shaped. It has been known.
- the second embodiment has the following configuration. That is, the ball screw of the second embodiment includes a screw shaft having a helical screw groove on the outer peripheral surface, a nut having a screw groove on the inner peripheral surface facing the screw groove of the screw shaft, and the both screw grooves.
- a ball screw comprising: a plurality of balls movably loaded in a spiral ball rolling path formed; and a ball circulation path for circulating the ball from an end point of the ball rolling path to a starting point.
- the circulation path is configured by a concave groove formed by recessing a part of the inner peripheral surface of the nut, and at least a part of the ball circulation path in the longitudinal direction is cut by a plane orthogonal to the longitudinal direction.
- the cross-sectional shape in this case is substantially V-shaped.
- the ball circulation path includes both end portions that are connection portions with the ball rolling path and an intermediate portion between the both end portions. At least one of the end portions preferably has a substantially V-shaped cross section when cut by a plane orthogonal to the longitudinal direction of the ball circulation path. Further, it is preferable to provide a lubricant reservoir at the bottom of the concave groove constituting the ball circulation path.
- at least a part of the ball circulation path in the longitudinal direction has a substantially V-shaped cross section when cut by a plane perpendicular to the longitudinal direction. Is small.
- FIG. 9 is a cross-sectional view (cross-sectional view cut along a plane along the axial direction) illustrating the structure of the ball screw of the first example of the second embodiment.
- the ball screw 1 has a screw shaft 3 having a helical thread groove 3 a on the outer peripheral surface and a helical screw groove 5 a facing the screw groove 3 a of the screw shaft 3 on the inner peripheral surface.
- a plurality of balls 9 movably loaded in a spiral ball rolling path 7 formed by the nut 5 and both screw grooves 3a, 5a, and the balls 9 are circulated back from the end point of the ball rolling path 7 to the starting point. And a ball circulation path 11 to be moved.
- the cross-sectional shape of the screw grooves 3a and 5a may be an arc shape (single arc shape) or a gothic arc shape.
- the material of the screw shaft 3, the nut 5, and the ball 9 is not particularly limited, and general materials can be used. For example, metal (steel etc.), sintered alloy, ceramic, and resin can be mentioned.
- the ball circulation path 11 will be described in detail with reference to cross-sectional views of FIGS. 10 and 11 (cross-sectional views cut along a plane orthogonal to the axial direction).
- the ball circulation path 11 is integrally formed on the inner peripheral surface of the nut 5. More specifically, a concave groove 22 formed by recessing a part of the cylindrical inner peripheral surface of the nut 5 by plastic working (for example, a method described later forging using a die) is formed into a ball circulation path. 11 is set. Therefore, unlike the case of a ball circulation type such as a tube type or a piece type, no separate member constituting the ball circulation path is attached. And since another member is not used, there is no possibility that the step which has an edge part which arises in a boundary part when another member is used will arise.
- the ball 9 rolling to the end point of the ball rolling path 7 is scooped up from one end of the ball circulation path 11 and sinks into the nut 5 (radially outward). . Then, the ball passes through the ball circulation path 11, gets over the land portion 3 b of the screw shaft 3 (the thread of the screw groove 3 a), and returns to the starting point of the ball rolling path 7 from the other end of the ball circulation path 11. Further, as shown in FIG. 12, the ball circulation path 11 (concave groove 22) has both end portions 11a and 11a that are connected to the ball rolling path 7 (screw groove 5a) in a straight line. The intermediate part 11b located between 11a and 11a is curvilinear.
- both ends of the intermediate portion 11b and both end portions 11a and 11a are smoothly connected, and the overall shape of the ball circulation path 11 (concave groove 22) viewed from the direction of arrow A in FIG. 10 is substantially S-shaped. ing.
- the overall shape of the ball circulation path 11 is not limited to a substantially S shape as shown in FIG.
- the straight end portion 11a forms the introduction portion of the ball 9, and the ball 9 entering the ball circulation passage 11 from the ball rolling path 7 hits the curved portion of the intermediate portion 11b through the introduction portion.
- this introduction portion is a portion where the ball 9 collides violently.
- the ball circulation path 11 and the ball rolling path 7 are smoothly connected. That is, the locus of contact between the ball 9 and the inner surface of the concave groove 22 and the locus of contact between the ball 9 and the inner surface of the thread groove 5a are connected so as to be smoothly continuous. As a result, the ball 9 circulates smoothly.
- FIGS. 13 is a cross-sectional view of the concave groove 22 showing the cross-sectional shape of the end portion 11a of the ball circulation path 11
- FIG. 14 is a cross-sectional view of the concave groove 22 showing the cross-sectional shape of the intermediate part 11b of the ball circulation path 11. is there.
- FIG. 15 is a cross-sectional view of the thread groove 5 a showing the cross-sectional shape of the ball rolling path 7. Any of the cross-sectional views is a cross-sectional view taken along a plane orthogonal to the longitudinal direction of the ball circulation path 11 or the ball rolling path 7.
- the cross-sectional shape of the ball circulation path 11 extending substantially in the circumferential direction of the nut 5 is the longitudinal direction. V-shaped as a whole.
- the cross-sectional shape of the end portion 11a of the ball circulation path 11 is shown in FIG.
- the cross-sectional shape of the end portion 11a is a V-shape formed by intersecting two straight lines.
- the tip portion Since the contact angle between the tip of the V-shaped convex part and the nut material is small, cold forging becomes easy and the energy required for forging is significantly reduced. Therefore, the energy required for manufacturing the ball screw 1 is small.
- the angle formed by the V-shaped portion is preferably 90 ° or more.
- the cross-sectional shape as a whole may not be V-shaped, and only the portion near the bottom of the groove 22 may be V-shaped in cross section.
- the cross-sectional shape of the intermediate portion 11b of the ball circulation path 11 is shown in FIG. If the cross-sectional shape is as shown in FIG. 14, the width of the concave groove 22 is smaller than that in the case of the V shape as shown in FIG. 13, so that the amount of thinning in forging can be reduced. Therefore, the energy required for forging becomes smaller.
- 14 has a V-shaped cross section in the vicinity of the bottom and a rectangular cross section in the vicinity of the opening. However, the vicinity of the opening may have a trapezoidal cross section.
- the cross-sectional shape of the ball circulation path 11 is V-shaped, as can be seen from FIGS. 13 and 14, the ball 9 is in contact with and supported by the inner surface of the concave groove 22 at two points. As a result, the behavior of the ball 9 in the ball circulation path 11 is stabilized. Furthermore, since the cross-sectional shape of the ball circulation path 11 is V-shaped, a space surrounded by the inner surface of the groove 22 and the ball 9 is formed at the bottom of the groove 22 constituting the ball circulation path 11. Since this space can hold a lubricant such as lubricating oil and grease, the space functions as a lubricant reservoir.
- the ball screw 1 Since the lubricant retained in the lubricant reservoir is appropriately supplied to the ball 9 during use of the ball screw 1, the lubricant adheres to the surface of the ball 9 in the ball circulation path 11, and the ball 9 rotates together with the ball 9. It reaches the runway 7 and is used for lubrication of the surfaces of the thread grooves 3a and 5a and the ball 9. Therefore, the ball screw 1 has excellent lubricity and a long life. Further, since the ball screw 1 is lubricated by the lubricant held in the lubricant reservoir, the frequency of maintenance work for supplying the lubricant to the inside of the ball screw 1 can be reduced.
- the use of the ball screw 1 of the first example is not particularly limited, but can be suitably used for automobile parts, positioning devices and the like.
- the columnar steel material 20 was processed by plastic working such as cold forging to obtain a blank 21 having substantially the same shape (substantially cylindrical shape) as the nut 5 (rough forming step).
- the flange 13 is also formed on the outer peripheral surface of the blank 21 by plastic working.
- a part of the cylindrical inner peripheral surface of the blank 21 is recessed by plastic working such as cold forging, and a substantially S-shape that forms a ball circulation path 11 that communicates the end point and the start point of the ball rolling path 7.
- a concave groove 22 was formed (ball circulation path forming step).
- the method for forming the concave groove 22 include the following. That is, a mold (not shown) having a convex portion corresponding to the concave groove 22 is inserted into the blank 21, the convex portion of the mold is brought into contact with the inner peripheral surface of the blank 21, and the inner periphery of the blank 21 is
- the groove 22 can be formed by plastic working by strongly pressing the mold toward the surface.
- the concave groove 22 may be formed using a mold of a cam mechanism having a cam driver and a cam slider having a convex portion corresponding to the concave groove 22. . More specifically, a cam driver and a cam slider are inserted into the blank 21. At that time, the cam slider is disposed between the blank 21 and the cam driver, and the convex portion is disposed toward the inner peripheral surface of the blank 21. The cam slider and the cam driver arranged in the blank 21 are in contact with each other at an inclined surface extending in a substantially axial direction of the blank 21 (a direction slightly inclined from the axial direction of the blank 21). A cam mechanism is configured.
- the thread groove 5a is formed on the inner peripheral surface of the nut 5 so as to be connected to the end of the ball circulation path 11 (concave groove 22) by a conventional cutting process (for example, a method shown in FIG. 24 described later). Formed (thread groove forming step).
- the outermost end portion of the concave groove 22 (ball circulation path 11) has a spherical shape, an edge portion as in the case of a piece type ball screw is not generated at the step of the boundary portion 30 with the screw groove 5a. It becomes a smooth step. As a result, even if the ball 9 passes through the boundary portion 30, abnormal noise and operating torque fluctuations are less likely to occur, and the lifetime is not likely to decrease.
- heat treatment such as quenching and tempering was performed under desired conditions, and the nut 5 was obtained.
- the heat treatment include carburizing treatment, carbonitriding treatment, and high-frequency heat treatment.
- the material of the nut 5 is preferably chromium steel or chromium molybdenum steel (for example, SCM420) having a carbon content of 0.10 to 0.25% by mass
- carbon steel having a carbon content of 0.4 to 0.6% by mass for example, S53C, SAE4150 is preferable.
- the ball screw 1 was manufactured by combining the nut 5 manufactured in this way, the screw shaft 3 and the ball 9 manufactured by a conventional method. Since the rough forming step and the ball circulation path forming step described above are performed by plastic working, the manufacturing method of the ball screw 1 can manufacture a high-precision ball screw at a low cost in addition to a high material yield. Can do. Moreover, since it manufactures by plastic processing, since the metal flow (forged streamline) which the steel raw material 20 has is hardly cut
- the type of plastic working is not particularly limited, but forging is preferable, and cold forging is particularly preferable. Although hot forging can be used, cold forging can finish with higher accuracy than hot forging, so it is possible to obtain a sufficiently accurate nut 5 without post-processing. Can do. Therefore, the ball screw 1 can be manufactured at low cost.
- the plastic working in the rough forming step and the ball circulation path forming step is preferably cold forging, but the plastic working in any one step may be cold forging.
- the cross-sectional shape of the ball circulation path 11 is V-shaped in the entire longitudinal direction, but a part of the ball circulation path 11 (a part of the ball circulation path 11 in the longitudinal direction).
- the cross-sectional shape may be V-shaped.
- the intermediate portion 11b has a V-shaped cross section, and the cross-sectional shapes of both end portions 11a and 11a are an arc shape (single arc shape) or a gothic arc shape. . Since the intermediate portion 11b having the largest amount of thickness removal during forging has a V-shaped cross section, the energy required for forging is significantly reduced.
- both end portions 11a and 11a have a V-shaped cross section
- the cross-sectional shape of the intermediate portion 11b is an arc shape (single arc shape). Or it has a Gothic arc shape.
- the end portion 11a which is the introduction portion of the ball 9, is a portion where the ball 9 moves from the load region to the no-load region, and is the portion where the behavior of the ball 9 is most unstable. Since the cross-sectional shape of such a portion is V-shaped, and the ball 9 is in contact with and supported by the inner surface of the concave groove 22 at two points, the behavior of the ball 9 is stabilized. Further, if the cross-sectional shape of the intermediate portion 11b in which the ball 9 moves by sliding is an arc shape or a substantially U shape in which the ball 9 contacts the inner surface of the concave groove 22 at one point, wear loss of the ball 9 is reduced. be able to.
- the first to third examples are examples of the second embodiment, and the second embodiment is not limited to the first to third examples.
- the example in which the concave groove 22 is formed by forging is shown in the ball screw 1 of the first to third examples.
- a part of the cylindrical inner peripheral surface of the blank 21 is formed by a method other than forging.
- the concave groove 22 may be formed by making it concave. For example, you may make it concave by removal processes, such as cutting, grinding, and electrical discharge.
- the blank 21 having the concave groove 22 on the inner peripheral surface may be manufactured by casting, and the concave groove 22 may be used as the ball circulation path 11.
- the concave groove 22 is formed by these methods, the effect that the energy required for manufacturing the ball screw 1 is small is not achieved, but the effect that the behavior of the ball 9 in the ball circulation path 11 is stabilized is achieved. Is done.
- a nut circulation type ball screw in which a ball circulation path 11 for circulating the ball 9 from the end point of the ball rolling path 7 to the start point is formed in the nut 5 is illustrated.
- the second embodiment can also be applied to a screw screw circulation type ball screw in which a screw shaft corresponding to the ball circulation path 11 is formed.
- the third embodiment relates to a method for manufacturing a ball screw.
- the ball screw is a spiral ball rolling path formed by a screw shaft having a helical thread groove on the outer peripheral surface, a nut having a screw groove facing the screw groove of the screw shaft on the inner peripheral surface, and both screw grooves. And a plurality of balls loaded in a rollable manner. Then, when the nut and the screw shaft that are screwed to the screw shaft through the ball are relatively rotated, the screw shaft and the nut are relatively moved in the axial direction through the rolling of the ball. .
- Such a ball screw is provided with a ball circulation path that forms an endless ball path by connecting the start point and end point of the ball rolling path. That is, the ball moves around the screw shaft while moving in the ball rolling path and reaches the end point of the ball rolling path. The ball is scooped up from one end of the ball circulation path and passes through the ball circulation path. The ball is returned to the starting point of the ball rolling path from the other end of the circulation path.
- the screw shaft and the nut can continuously move relative to each other.
- a ball circulation type using a ball circulation path a tube type, a top type, etc. are common.
- a top 102 provided with a circulation groove 101 constituting a ball circulation path is inserted into a top hole 104 formed in a nut 103 and fixed.
- the nut 103 of such a top ball screw is manufactured by drilling a cylindrical material by cutting or processing the inner and outer peripheral surfaces, so that the material yield is poor.
- a step 105 having an edge portion may occur at the boundary due to the variation in the size of the nut 103 and the piece 102 (the pieces 102 and the piece holes 104 Please refer to Fig. 21 which shows an enlarged view of the peripheral portion and the peripheral portion of the step, where reference numeral 100 is a ball rolling path).
- step difference when the machining using a grindstone, an end mill, etc. was given, there existed a possibility that an abrasive grain, a chip, etc. might remain between a top and a top hole.
- Patent Document 6 is a prior art for solving these problems.
- shot peening is performed on a portion adjacent to a top hole in a screw groove of the nut before the top is attached to the nut. Shot peening is also applied to the circulation groove of the top.
- shot peening is expensive, there is a problem that processing cost increases.
- the return groove constituting the ball circulation path is integrally formed on the inner peripheral surface of the nut by forming the nut from a sintered alloy. That is, since the nut and the ball circulation path are formed integrally rather than as separate members, the step having the edge portion as described above is not formed.
- the third embodiment is intended to solve the above-described problems of the prior art, and to provide a ball screw manufacturing method that is unlikely to generate abnormal noise and fluctuations in operating torque and that is long-lived and inexpensive.
- the ball screw manufacturing method of the third embodiment includes a screw shaft having a helical thread groove on the outer peripheral surface, a nut having a screw groove facing the screw groove of the screw shaft on the inner peripheral surface, A ball screw comprising: a plurality of balls slidably loaded in a spiral ball rolling path formed by a thread groove; and a ball circulation path for circulating the ball from the end point of the ball rolling path to a starting point.
- a part of the inner peripheral surface of the nut is recessed to form the ball circulation path formed of a concave groove, and the ball circulation path is formed on the inner peripheral surface of the nut.
- a thread groove forming step for forming the thread groove so as to be connected to an end of the ball, and a burr for removing at least one of brushing and blasting at a boundary portion between the ball circulation path and the ball rolling path. Removal Characterized in that it comprises a step.
- a part of the inner peripheral surface of the nut is recessed by forging, and the ball circulation path formed of a groove is formed. It may be formed. Since the ball screw manufacturing method according to the third embodiment includes a burr removing step for removing burrs generated at the boundary between the ball circulation path and the ball rolling path, abnormal noise is generated when the ball passes through the boundary. In addition, it is possible to manufacture a long-life ball screw that is less likely to cause fluctuations in operating torque.
- FIG. 9 is a cross-sectional view (cross-sectional view cut along a plane along the axial direction) of an example of the ball screw of the third embodiment.
- the ball screw 1 has a screw shaft 3 having a helical thread groove 3 a on the outer peripheral surface and a helical screw groove 5 a facing the screw groove 3 a of the screw shaft 3 on the inner peripheral surface.
- a plurality of balls 9 movably loaded in a spiral ball rolling path 7 formed by the nut 5 and both screw grooves 3a, 5a, and the balls 9 are circulated back from the end point of the ball rolling path 7 to the starting point. And a ball circulation path 11 to be moved.
- the ball 9 moves around the screw shaft 3 while moving in the ball rolling path 7 to reach the end point of the ball rolling path 7, where it is scooped up from one end portion of the ball circulation path 11 to be ball circulation path. 11, the ball circulation path 11 is returned to the starting point of the ball rolling path 7 from the other end of the ball circulation path 11.
- the cross-sectional shape of the thread grooves 3a and 5a may be an arc shape or a gothic arc shape.
- the material of the screw shaft 3, the nut 5, and the ball 9 is not particularly limited, and general materials can be used, and examples thereof include metals (steel etc.), ceramics, and resins.
- metals such as steel
- strength as a nut of a ball screw can be provided.
- the ball circulation path 11 will be described in detail with reference to cross-sectional views of FIGS. 10 and 11 (cross-sectional views cut along a plane orthogonal to the axial direction).
- the ball circulation path 11 is integrally formed on the inner peripheral surface of the nut 5. More specifically, the groove 22 formed by recessing a part of the cylindrical inner peripheral surface of the nut 5 by plastic working or cutting is used as the ball circulation path 11. Therefore, unlike the case of a ball circulation type such as a tube type or a piece type, no separate member constituting the ball circulation path is attached. And since another member is not used, there is no possibility that the step which has an edge part which arises in a boundary part when another member is used will arise.
- the ball 9 rolling to the end point of the ball rolling path 7 is scooped up from one end of the ball circulation path 11 and sinks into the nut 5 (radially outward). . Then, the ball passes through the ball circulation path 11, gets over the land portion 3 b of the screw shaft 3 (the thread of the screw groove 3 a), and returns to the starting point of the ball rolling path 7 from the other end of the ball circulation path 11.
- the cross-sectional shape of the ball circulation path 11 may be an arc shape or a gothic arc shape.
- the use of the ball screw 1 of this example of the third embodiment is not particularly limited, but can be suitably used for automobile parts, positioning devices, and the like.
- the columnar steel material 20 was processed by plastic working such as cold forging to obtain a blank 21 having substantially the same shape (substantially cylindrical shape) as the nut 5 (rough forming step).
- the flange 13 is also formed on the outer peripheral surface of the blank 21 by plastic working.
- a concave groove 22 forming the path 11 was formed (ball circulation path forming step).
- Specific examples of the method for forming the concave groove 22 include the following. That is, a mold (not shown) having a convex portion corresponding to the concave groove 22 is inserted into the blank 21, the convex portion of the mold is brought into contact with the inner peripheral surface of the blank 21, and the inner periphery of the blank 21 is The groove 22 can be formed by plastic working by strongly pressing the mold toward the surface.
- the concave groove 22 may be formed using a mold of a cam mechanism having a cam driver and a cam slider having a convex portion corresponding to the concave groove 22. . More specifically, a cam driver and a cam slider are inserted into the blank 21. At that time, the cam slider is disposed between the blank 21 and the cam driver, and the convex portion is disposed toward the inner peripheral surface of the blank 21. The cam slider and the cam driver arranged in the blank 21 are in contact with each other at an inclined surface extending in a substantially axial direction of the blank 21 (a direction slightly inclined from the axial direction of the blank 21). A cam mechanism is configured.
- a thread groove 5a is formed on the inner peripheral surface of the nut 5 so as to be connected to the end of the ball circulation path 11 (concave groove 22) by a conventional cutting process (for example, a method shown in FIG. 24 described later).
- a conventional cutting process for example, a method shown in FIG. 24 described later.
- the ball circulation path 11 and the ball rolling path 7 are smoothly connected. As a result, even if the ball 9 passes through the boundary portion 30, no abnormal noise or fluctuation in operating torque is caused, and the life is hardly reduced. Further, when brushing or blasting is performed, fatigue strength is improved by compressive residual stress on the surface. Further, since the brushing and blasting are less expensive than the shot peening, the ball screw 1 can be manufactured at a low cost. Furthermore, since no burrs are present in the boundary portion 30 by brushing or blasting, and the surface is flattened, the balls 9 can be circulated more smoothly due to these effects. In addition, the flat surface shape is a curved chamfered shape.
- a brush made of steel, stainless steel, polyamide resin (nylon) or the like can be used.
- This brush may be a brush provided with abrasive grains.
- the kind of abrasive grains is not particularly limited, but alumina, silicon carbide, diamond and the like are preferable.
- Blasting is a process of spraying media from the blast nozzle onto the boundary portion 30.
- the type of media is not particularly limited, but plastics such as steel, glass, alumina, and polyamide resin (nylon) are preferable.
- the time for blowing the media is not particularly limited, but is preferably 2 seconds or more and 5 seconds or less, and more preferably around 3 seconds.
- the surface roughness of the boundary portion 30 after the burr removing step is 1.6 ⁇ mRa or less.
- heat treatment such as quenching and tempering was performed under desired conditions, and the nut 5 was obtained.
- the heat treatment include carburizing treatment, carbonitriding treatment, and high-frequency heat treatment. Note that such heat treatment may be performed before the burr removing step. When brushing or blasting is performed after heat treatment, the effect of improving fatigue strength due to compressive residual stress on the surface is further enhanced.
- the heat treatment is carburizing or carbonitriding
- the material of the nut 5 is preferably SCM420, and when the heat treatment is induction hardening, it is preferably S53C or SAE4150.
- the ball screw 1 was manufactured by combining the nut 5 manufactured in this way, the screw shaft 3 and the ball 9 manufactured by a conventional method. Since the above-described rough forming process and ball circulation path forming process are performed by plastic working, the manufacturing method of the ball screw 1 can manufacture a high-precision ball screw at a low cost in addition to a high material yield. . Moreover, since it manufactures by plastic processing, since the metal flow (forged streamline) which the steel raw material 20 has is hardly cut
- the type of plastic working is not particularly limited, but forging is preferable, and cold forging is particularly preferable.
- hot forging can be used, cold forging can finish with higher accuracy than hot forging, so it is possible to obtain a sufficiently accurate nut 5 without post-processing. Can do. Therefore, the ball screw 1 can be manufactured at low cost.
- the plastic working in the rough forming step and the ball circulation path forming step is preferably cold forging, but the plastic working in any one step may be cold forging. Moreover, you may combine cutting etc. in plastic processing.
- the third embodiment is not limited to this example.
- the ball circulation path 11 for circulating the ball 9 from the end point of the ball rolling path 7 back to the start point is illustrated as an example in the nut circulation type ball screw. Is applicable to a ball screw of a screw shaft circulation type in which a screw shaft corresponding to the ball circulation path 11 is formed.
- the fourth embodiment relates to a method of manufacturing a nut constituting a ball screw, a mold used in the manufacturing method, and a ball screw nut manufactured by the manufacturing method.
- the ball screw is disposed between a nut having a spiral groove formed on the inner peripheral surface, a screw shaft having a spiral groove formed on the outer peripheral surface, and a raceway formed by the spiral groove of the nut and the spiral groove of the screw shaft.
- Such a ball screw is used not only for a general industrial machine positioning device but also for an electric actuator mounted on a vehicle such as an automobile, a two-wheeled vehicle or a ship.
- the ball return path of the ball screw includes a circulation tube system, a top system, and the like.
- a top formed with a recess that forms the ball return path is fitted in the through hole of the nut.
- Patent Document 1 describes that a recess (circulation groove) that forms a ball return path is formed directly on the inner peripheral surface of a nut material by plastic working. The formation method will be described with reference to FIG.
- a mold having a cylindrical processing head 530 having S-shaped convex portions 537 and 538 corresponding to the shape of the circulation groove is prepared. Then, the nut material 510 is placed on the table 200 with its axial direction oriented in the horizontal direction, the machining head 530 is placed inside the nut material 510, the convex portions 537 and 538 are directed upward, and the base end portion 530a. And the tip 530b are fixed.
- the upper member 520 of the mold is lowered by applying a pressing pressure, and the convex portions 537 and 538 are pressed against the inner peripheral surface 511 of the nut material 510, whereby the inner peripheral surface 511 of the nut material 510 is pressed. Is plastically deformed (see FIG. 26B).
- the wear powder generated in the circulation path is mixed in a lubricant such as grease, so that the lubricating oil film formed on the surface of the ball screw groove is partially broken, the lubrication performance is lowered and the temperature rises. There is concern about causing premature wear.
- a lubricant such as grease
- the fourth embodiment has been made paying attention to the above-mentioned problems, and its purpose is to produce a ball screw nut capable of preventing indentation and surface peeling without increasing the number of steps, and It is providing the metal mold
- the metal mold die which concerns on 1 aspect of 4th Embodiment for solving the said subject,
- the spiral groove of a nut And a plurality of ball return paths for returning the ball from the end point of the track to the start point, formed as a plurality of recesses on the inner peripheral surface of the nut.
- a cam driver that is inserted and moves along the axial direction of the cam driver, and is disposed between the nut material and the cam driver, and a plurality of convex portions corresponding to the plurality of concave portions are formed.
- the plurality of convex portions are the nuts.
- a cam slider to move in the radial direction, the arithmetic average roughness Ra 1 of the surface of at least the plurality of convex portions, 0.01 [mu] m or more, and wherein the at 0.2 ⁇ m or less.
- the arithmetic average roughness Ra 1 of the surface of the convex portion of the cam slider is set to 0.01 ⁇ m or more and 0.2 ⁇ m or less. Therefore, the nut is formed by forging using the cam slider. The surface roughness of the recess formed on the inner peripheral surface of the material can be reduced to such an extent that indentation and surface peeling can be prevented.
- a ball screw nut manufacturing method includes a nut having a spiral groove formed on an inner peripheral surface, and a screw shaft having a spiral groove formed on an outer peripheral surface.
- a ball disposed between the raceway formed by the spiral groove of the nut and the spiral groove of the screw shaft, and the ball formed as a plurality of recesses on the inner peripheral surface of the nut, and returning the ball from the end point to the start point
- a ball screw manufacturing method comprising: a plurality of ball return paths, wherein the nut moves relative to a screw shaft as the ball rolls in the track; The plurality of recesses are simultaneously formed on the inner peripheral surface of the nut material by forging using the mold.
- the cam driver is inserted into the cylindrical nut material and moves along the axial direction thereof, and is disposed between the nut material and the cam driver.
- the plurality of convex portions formed on the cam slider forge the inner peripheral surface of the nut material, whereby the plurality of concave portions are formed on the inner peripheral surface of the nut material.
- the arithmetic mean roughness Ra 1 of the surface of at least the plurality of convex portions of the mold is 0.01 ⁇ m or more and 0.2 ⁇ m or less, the concave portion formed by forging by the convex portions is formed.
- the arithmetic average roughness Ra 2 of the surface is more than 0 ⁇ m and 1.6 ⁇ m or less.
- a ball screw nut for solving the above-described problem is provided with a nut having a spiral groove formed on the inner peripheral surface, a screw shaft having a spiral groove formed on the outer peripheral surface, A ball arranged between a spiral groove and a raceway formed by a spiral groove of a screw shaft, and a plurality of balls formed as a plurality of recesses on the inner peripheral surface of the nut to return the ball from the end point to the start point
- a nut of a ball screw in which the nut moves relative to the screw shaft by rolling the ball in the track, and the arithmetic average roughness Ra 2 of the surface of the recess is It is characterized by being more than 0 ⁇ m and 1.6 ⁇ m or less.
- Nuts can be provided.
- a ball screw nut manufacturing method capable of preventing indentation and surface peeling without increasing the number of steps, a mold used in the manufacturing method, and a ball manufactured by the manufacturing method A screw nut can be provided.
- FIG. 23 is a plan view (a) showing a fitting state of a cam slider and a cam driver constituting a mold used in an example of a ball screw nut manufacturing method according to the fourth embodiment, and a perspective view showing the cam slider.
- FIG. 2B is a perspective view showing the cam driver.
- a mold 450 used in this example of the fourth embodiment includes a material holder 420 having a recess 421 for holding a nut material 410, a cam slider 430 and a cam driver arranged inside the nut material 410. 440.
- the cam slider 430 is a substantially semi-cylindrical member having a plane 432 parallel to the outer peripheral surface 431 and the axial direction, and the diameter of the circle forming the outer peripheral surface 431 is: The diameter is slightly smaller than the diameter of the circle 411 a forming the inner peripheral surface 411 of the nut material 410.
- an inclined surface 433 extending in the axial direction is formed at the central portion in the radial direction.
- the inclined surface 433 corresponds to a plane connecting the bottom surface line 434 a of the recess 434 at one end (upper end) in the axial direction and the line 432 d forming the lower end of the plane 432.
- an S-shaped convex portion 435 corresponding to the S-shaped concave portion 415 forming the ball return path is formed on the outer peripheral surface 431 of the cam slider 430.
- at least the surface 435a of the convex portion 435 is mirror-finished by, for example, buffing. By this mirror finishing, the arithmetic average roughness Ra 1 of the surface 435a is set to 0.01 ⁇ m or more and 0.2 ⁇ m or less.
- the cam driver 440 is a long plate-like member, and one side surface 441 is an inclined surface having the same inclination as the inclined surface 433 of the cam slider 430.
- the other side surface 442 is a circumferential surface along a circle 411 a forming the inner circumferential surface 411 of the nut material 410.
- the axial dimension of the cam driver 440 is longer than the axial dimension of the cam slider 430.
- the thickness of the cam driver 440 is slightly smaller than the thickness corresponding to the opening width of the recess 434 of the cam slider 430 (the dimension between both side surfaces of the inclined surface 433).
- the inclined surface 431 of the cam slider 430 and the inclined side surface 441 of the cam driver 440 constitute a cam mechanism of the mold 450.
- the circulation groove forming step of forming the circulation groove on the inner peripheral surface 411 of the nut material 410 and the inner peripheral surface 411 based on the position of the formed circulation groove are provided.
- a rolling groove forming step of forming the rolling groove is provided.
- the material of the nut material 410 is preferably SCM420 when the heat treatment after the rolling groove forming step and the circulating groove forming step described below is carburizing treatment, and is S53C or SAE4150 when induction hardening is performed. Is preferred.
- an S-shaped recess 415 that forms a ball return path (circulation groove) is formed on the inner peripheral surface 411 of the nut material 410 by the following method.
- the nut material 410 is disposed in the recess 421 of the material holder 420, the cam slider 430 is placed inside the nut material 410, the recess 434 side is up, and the S-shaped protrusion 435 is placed on the inner peripheral surface 411 of the nut material 410. Insert to face.
- the cam driver 440 is inserted between the cam slider 430 and the nut material 410.
- FIG. 22A shows this state.
- an S-shaped recess 415 that forms a ball return path is formed on the inner peripheral surface 411 of the nut material 410 by forging. Specifically, when a press pressure is applied and the cam driver 440 is pushed from above, a force is transmitted from the inclined side surface 441 of the cam driver 440 to the inclined surface 433 of the cam slider 430. Along with this, the downward force of the cam driver 440 is converted into a force that moves the cam slider 430 radially outward, and the S-shaped convex portion 435 formed on the cam slider 430 presses the inner peripheral surface 411 of the nut material 410. Plastic processing. FIG. 22B shows this state.
- an S-shaped recess 415 that forms a ball return path is formed in the inner peripheral surface 411 of the nut material 410. Therefore, according to the method of this example of the fourth embodiment, the S-shaped recess 415 can be formed without causing damage to the cam driver 440 even when a nut having a long axial dimension and a small inner diameter is manufactured. it can.
- the cam slider 430 is removed after the cam driver 440 is pulled out after forming one S-shaped concave portion 415 by the above-described method.
- the position of the convex portion 435 is changed by moving, and the cam driver 440 is inserted again to perform the above-described method. This is repeated when three or more S-shaped concave portions 415 are formed.
- FIG. 24 is a view for explaining an example of a ball screw nut manufacturing method according to the fourth embodiment
- (a) is a perspective view showing a state of cutting a nut material
- (b) It is the figure which looked at the nut raw material and cutting tool which are shown to (a) in the arrow VA direction.
- FIG. 25 is a view for explaining an example of a ball screw nut manufacturing method according to the fourth embodiment.
- FIG. 25A is an axial sectional view after the nut material is cut, and FIG. These are the perspective views after the cutting process of a nut raw material.
- the cutting tool T forms a blade Tb on the outer periphery of the rotation axis Ta.
- the cutting surface (surface facing in the circumferential direction) of the blade Tb matches the shape of the rolling groove 416.
- the rotation axis Ta rotates around its axis O (A in FIG. 24B), but independently revolves around the eccentric axis Q (B in FIG. 24B).
- a mechanism for rotating and revolving the cutting tool T in this way for example, a configuration in which the rotation shaft Ta is connected to a planetary gear of a planetary gear mechanism (not shown) is conceivable, but not limited thereto.
- the rotational axis Ta of the cutting tool T is shifted radially outward at a predetermined axial position, and revolved while being sent in the axial direction at the pitch of the rolling grooves 416, and at a higher speed.
- the spiral rolling groove 416 of less than 360 degrees can be cut and formed on the inner peripheral surface of the nut material 410.
- each circulation groove 415 can be connected to both ends of the rolling groove 416 as shown in FIG.
- the same nut material 410 is cut twice, but if two blades Tb are formed on the rotation axis Ta. It can be formed by a single cutting process.
- the arithmetic average roughness Ra 1 of the surface 435a of the S-shaped convex portion 435 formed on the cam slider 430 is 0.01 ⁇ m or more and 0.2 ⁇ m or less, it is formed using a mold 450 having the cam slider 430.
- the arithmetic average roughness Ra 2 of the circulation groove 416 is more than 0 ⁇ m and 1.6 ⁇ m or less.
- the arithmetic average roughness Ra 2 of the circulation groove 416 is at least the roughness of the region in contact with the ball (rolling element) in the circulation groove 416.
- the ball screw nut in which the circulation groove 416 is formed on the inner peripheral surface in this way is a ball screw nut manufacturing method and a manufacturing method thereof that are small enough to prevent indentation and surface peeling. It is possible to provide a ball screw nut manufactured by a mold used in the above and a manufacturing method thereof. Further, if the arithmetic average roughness Ra 1 of the surfaces of the convex portions 537 and 538 of the processing head 530 is set to 0.01 to 0.2 ⁇ m, even if the method shown in FIG. A circulation groove 416 can be formed. In addition, it does not specifically limit about the processing method of parts other than the circulation groove
- 4th Embodiment is the above-mentioned.
- the present invention is not limited to this example, and various modifications can be made without departing from the spirit of the fourth embodiment.
- the ball screw nut manufacturing method according to the fourth embodiment, the mold used in the manufacturing method, and the ball screw nut manufactured by the manufacturing method are a ball screw nut adopting screw shaft circulation. Is also applicable.
- the fifth embodiment relates to a ball screw and a manufacturing method thereof.
- the ball screw is a spiral ball rolling path formed by a screw shaft having a helical thread groove on the outer peripheral surface, a nut having a screw groove facing the screw groove of the screw shaft on the inner peripheral surface, and both screw grooves. And a plurality of balls loaded in a rollable manner. Then, when the nut and the screw shaft that are screwed to the screw shaft through the ball are relatively rotated, the screw shaft and the nut are relatively moved in the axial direction through the rolling of the ball. .
- Such a ball screw is provided with a ball circulation path that forms an endless ball path by connecting the start point and end point of the ball rolling path. That is, the ball moves around the screw shaft while moving in the ball rolling path and reaches the end point of the ball rolling path. The ball is scooped up from one end of the ball circulation path and passes through the ball circulation path. The ball is returned to the starting point of the ball rolling path from the other end of the circulation path.
- the screw shaft and the nut can continuously move relative to each other.
- a tube type, a top type, etc. are common.
- a tube type ball screw a tube constituting a ball circulation path is inserted and fixed in a hole formed in a nut.
- a top provided with a circulation groove that constitutes a ball circulation path is inserted and fixed in a top hole formed in the nut.
- Patent Document 8 For the purpose of improving the strength of the nut, a technique for hardening the surface of the nut by induction hardening is known (see, for example, Patent Document 8).
- tube-type and top-type ball screws a hole that penetrates the inner and outer peripheral surfaces of the nut is provided to fix the tube and the piece, so induction hardening is not performed uniformly in the circumferential direction. It was not easy.
- the ball screw disclosed in Patent Document 10 a tube and a piece are not used, and the ball circulation path is directly formed on the inner peripheral surface of the nut by plastic working. It can be applied uniformly in the direction.
- the fifth embodiment solves the problems of the prior art as described above, and provides a ball screw that can reduce the size of the nut and a method for manufacturing the same, in addition to excellent durability of the nut.
- the task is to do.
- the fifth embodiment has the following configuration. That is, the ball screw of the fifth embodiment includes a screw shaft having a helical screw groove on the outer peripheral surface, a nut having a screw groove on the inner peripheral surface facing the screw groove of the screw shaft, and the both screw grooves.
- a ball screw comprising: a plurality of balls movably loaded in a spiral ball rolling path formed; and a ball circulation path for circulating the ball from an end point of the ball rolling path to a starting point.
- the circulation path is constituted by a groove formed by recessing a part of the inner peripheral surface of the nut, and the surface hardness of the thread groove of the nut is HRC 58 or more and 62 or less, and the ball circulation path
- the surface hardness of both end portions, which are connected to the ball rolling path, is HRC 58 or more and 62 or less, and the surface hardness of the intermediate portion between the both end portions of the ball circulation path is HV550 or less.
- the concave groove constituting the ball circulation path is formed by forging. Further, in the ball screw manufacturing method of the fifth embodiment, when manufacturing the ball screw as described above, the concave groove constituting the ball circulation path is formed by forging, and the screw groove of the nut is formed by cutting. Then, induction hardening is performed on only the both ends of the ball circulation path and the thread groove of the nut.
- the thin portion of the nut is not hardened and has excellent toughness, so that the nut can be miniaturized in addition to the excellent durability of the nut.
- the ball screw manufacturing method of the fifth embodiment performs induction hardening so that the thin portion of the nut is not hardened. Therefore, in addition to excellent nut durability, a ball screw having a small nut is used. Can be manufactured.
- FIG. 9 is a cross-sectional view (a cross-sectional view cut along a plane along the axial direction) of a ball screw as an example of the fifth embodiment.
- the ball screw 1 has a screw shaft 3 having a helical thread groove 3 a on the outer peripheral surface and a helical screw groove 5 a facing the screw groove 3 a of the screw shaft 3 on the inner peripheral surface.
- a plurality of balls 9 movably loaded in a spiral ball rolling path 7 formed by the nut 5 and both screw grooves 3a, 5a, and the balls 9 are circulated back from the end point of the ball rolling path 7 to the starting point. And a ball circulation path 11 to be moved.
- the ball 9 moves around the screw shaft 3 while moving in the ball rolling path 7 to reach the end point of the ball rolling path 7, where it is scooped up from one end portion of the ball circulation path 11 to be ball circulation path. 11, the ball circulation path 11 is returned to the starting point of the ball rolling path 7 from the other end of the ball circulation path 11.
- the cross-sectional shape of the thread grooves 3a and 5a may be an arc shape (single arc shape) or a gothic arc shape.
- the material of the nut 5 is a metal material such as steel. Specifically, S53C and SAE4150 are preferable.
- the material of the screw shaft 3 and the ball 9 is not particularly limited, and a general material can be used. For example, metal (steel etc.), ceramic, and resin can be mentioned.
- carburized steel such as SCM415 and SCM420 is preferable, and for the ball 9, bearing steel and ceramic such as SUJ2 are preferable.
- the ball circulation path 11 will be described in detail with reference to cross-sectional views of FIGS. 10 and 11 (cross-sectional views cut along a plane orthogonal to the axial direction).
- the ball circulation path 11 is integrally formed on the inner peripheral surface of the nut 5. More specifically, the concave groove 22 formed by recessing a part of the cylindrical inner peripheral surface of the nut 5 by plastic working or removal processing (for example, cutting processing, electric discharge processing) is used as the ball circulation path 11. Therefore, unlike the case of a ball circulation type such as a tube type or a piece type, no separate member constituting the ball circulation path is attached.
- the ball 9 rolling to the end point of the ball rolling path 7 is scooped up from one end of the ball circulation path 11 and sinks into the nut 5 (radially outward). . Then, the ball passes through the ball circulation path 11, gets over the land portion 3 b of the screw shaft 3 (the thread of the screw groove 3 a), and returns to the starting point of the ball rolling path 7 from the other end of the ball circulation path 11.
- the cross-sectional shape of the ball circulation path 11 may be an arc shape (single arc shape) or a gothic arc shape.
- the application of the ball screw 1 of this example of the fifth embodiment is not particularly limited, but can be suitably used for automobile parts, positioning devices and the like.
- an example of the manufacturing method of the ball screw 1 of 5th Embodiment is demonstrated, referring FIG.
- the columnar steel material 20 was processed by plastic working such as cold forging to obtain a blank 21 having substantially the same shape (substantially cylindrical shape) as the nut 5 (rough forming step).
- the flange 13 is also formed on the outer peripheral surface of the blank 21 by plastic working.
- a part of the cylindrical inner peripheral surface of the blank 21 is recessed by plastic working such as cold forging (or may be cutting), and the ball circulation connects the end point and the start point of the ball rolling path 7.
- a concave groove 22 forming the path 11 was formed (ball circulation path forming step). At this time, you may form the recessed part which comprises an oil sump with the recessed groove 22 by plastic working (or cutting may be sufficient). Specific examples of the method for forming the concave groove 22 include the following.
- a mold (not shown) having a convex portion corresponding to the concave groove 22 is inserted into the blank 21, the convex portion of the mold is brought into contact with the inner peripheral surface of the blank 21, and the inner periphery of the blank 21 is
- the groove 22 can be formed by plastic working by strongly pressing the mold toward the surface.
- the groove 22 may be formed by using a cam mechanism mold having a cam driver and a cam slider having a convex portion corresponding to the groove 22. More specifically, a cam driver and a cam slider are inserted into the blank 21. At that time, the cam slider is disposed between the blank 21 and the cam driver, and the convex portion is disposed toward the inner peripheral surface of the blank 21. The cam slider and the cam driver arranged in the blank 21 are in contact with each other at an inclined surface extending in a substantially axial direction of the blank 21 (a direction slightly inclined from the axial direction of the blank 21). A cam mechanism is configured.
- the cam slider moves outward in the radial direction of the blank 21 by the cam mechanism (wedge action) constituted by both inclined surfaces. That is, a force is transmitted from the inclined surface of the cam driver to the inclined surface of the cam slider, and the axial force of the cam driver is converted into a force that moves the cam slider radially outward.
- the convex portion of the cam slider strongly presses the inner peripheral surface of the blank 21, so that the concave groove 22 is formed on the inner peripheral surface of the blank 21 by plastic working.
- the method shown in FIG. 26 may be used instead of the method shown in FIG.
- a thread groove 5a is formed on the inner peripheral surface of the nut 5 by a conventional cutting process (for example, the method shown in FIG. 24) so as to be connected to the end of the ball circulation path 11 (concave groove 22). Groove forming step).
- the end portion of the concave groove 22 (ball circulation path 11) has a spherical shape, an edge portion as in the case of the top type ball screw does not occur at the step of the boundary portion 30 with the screw groove 5a. It becomes a smooth step. As a result, even if the ball 9 passes through the boundary portion 30, abnormal noise and operating torque fluctuations are less likely to occur, and the lifetime is not likely to decrease.
- induction hardening was performed on the inner peripheral surface of the nut 5 to obtain the nut 5.
- the kind of coolant used for quenching at the time of quenching is not specifically limited, water or oil is preferable.
- the contents of induction hardening will be described in detail with reference to FIG. 27 which is a sectional view of the nut 5 cut along a plane along the axial direction.
- induction hardening is performed on only a part of the inner peripheral surface of the nut 5 to form a hardened layer on the surface, and other parts are not cured without induction hardening. That is, induction hardening is applied to the thread groove 5a so that the surface hardness is HRC58 or more and 62 or less.
- induction hardening is performed on both ends of the ball circulation path 11 (concave groove 22), which is a connection portion with the ball rolling path 7, so that the surface hardness is set to HRC58 or more and 62 or less.
- the intermediate portion between the both end portions is not subjected to induction hardening, and the surface hardness is set to HV550 or less.
- a coil 32 for induction hardening is arranged on the inner peripheral surface of the nut 5 as shown in FIG. That is, the coil 32 is arranged along the entire thread groove 5a with respect to the thread groove 5a. Further, the coil 32 is arranged along the both ends only with respect to the ball circulation path 11 (concave groove 22). If the coil 32 is arranged in this way and induction hardening is performed, the entire screw groove 5a and only both ends of the ball circulation path 11 (concave groove 22) are quenched, and the middle of the ball circulation path 11 (concave groove 22). The part is not hardened.
- FIG. 28 is a cross-sectional view of the ball circulation path 11 (concave groove 22) cut along a plane orthogonal to the longitudinal direction of the ball circulation path 11.
- A, B, B ′, and C in FIG. 28 correspond to the cutting position symbols shown in FIG. 27.
- FIG. 28A is a cross-sectional view of the ball circulation path 11 (concave groove 22) cut along line A in FIG.
- an effective hardened layer (shown as a hatched portion in FIG. 28) is formed on the entire surface of the concave groove 22, as shown in A, B, and B ′ of FIG. Absent.
- A which is the central portion of the intermediate portion
- a slight effective hardened layer is formed only on both edge portions of the concave groove 22, but an effective hardened layer is formed on the groove bottom portion where the ball 9 contacts.
- B and B ′ which are the end portions of the intermediate portion, the effective hardened layer is formed only in the portion (one edge portion) where the traveling direction of the ball 9 changes and abuts when the ball 9 circulates.
- an effective hardened layer is formed on the entire surface of the concave groove 22 at both ends of the ball circulation path 11 as in the case of the thread groove 5a.
- the depth of the hardened layer formed in the screw groove 5a is preferably 1.0 mm or more and 2.0 mm or less in the direction from the center of curvature of the screw groove 5a toward the contact at the contact point with the ball 9.
- the effective hardened layer depth is preferably 0.4 mm or more.
- the thread groove 5a is a load zone that receives a load via the ball 9, but since a hardened layer is formed on the surface by induction hardening, it can withstand a large load.
- both ends of the ball circulation path 11 are connected to the ball rolling path 7 and are the parts where the balls 9 introduced from the ball rolling path 7 hit and receive impact, but the hardened layer is formed on the surface by induction hardening. Is formed, it can withstand the impact. In addition, wear hardly occurs. Therefore, the durability of the ball circulation path 11 is excellent.
- the middle part of the ball circulation path 11 is a no-load zone in which the ball 9 slides and the load is small, so it is not necessary to have a hardened layer. Rather, since it is not hardened and has excellent toughness, damage such as cracking is unlikely to occur. Further, since the concave groove 22 is deeper than the screw groove 5a, the portion of the nut 5 where the ball circulation path 11 is formed is thinner than the other portions. Therefore, even if the outer diameter of the nut is reduced (that is, even if the portion where the ball circulation path 11 is formed is made thinner), damage such as cracking is less likely to occur.
- the ball screw 1 was manufactured by combining the nut 5 manufactured in this way, the screw shaft 3 and the ball 9 manufactured by a conventional method. Since the above-described rough forming process and ball circulation path forming process are performed by plastic working, the manufacturing method of the ball screw 1 can manufacture a high-precision ball screw at a low cost in addition to a high material yield. . Moreover, since it manufactures by plastic processing, since the metal flow (forged streamline) which the steel raw material 20 has is hardly cut
- the type of plastic working is not particularly limited, but forging is preferable, and cold forging is particularly preferable. Although hot forging can be used, cold forging can finish with higher accuracy than hot forging, so it is possible to obtain a sufficiently accurate nut 5 without post-processing. Can do. Therefore, the ball screw 1 can be manufactured at low cost.
- the plastic working in the rough forming step and the ball circulation path forming step is preferably cold forging, but the plastic working in any one step may be cold forging.
- This example shows an example of the fifth embodiment, and the fifth embodiment is not limited to this example.
- a nut circulation type ball screw in which the ball circulation path 11 for circulating the ball 9 from the end point of the ball rolling path 7 to the start point is formed in the nut 5 is exemplified.
- the form can also be applied to a screw shaft circulation type ball screw in which a screw shaft corresponding to the ball circulation path 11 is formed.
- the sixth embodiment relates to a ball screw.
- the ball screw is a spiral ball rolling path formed by a screw shaft having a helical thread groove on the outer peripheral surface, a nut having a screw groove facing the screw groove of the screw shaft on the inner peripheral surface, and both screw grooves. And a plurality of balls loaded in a rollable manner. Then, when the nut and the screw shaft that are screwed to the screw shaft through the ball are relatively rotated, the screw shaft and the nut are relatively moved in the axial direction through the rolling of the ball. .
- Such a ball screw is provided with a ball circulation path that forms an endless ball path by connecting the start point and end point of the ball rolling path. That is, the ball moves around the screw shaft while moving in the ball rolling path and reaches the end point of the ball rolling path. The ball is scooped up from one end of the ball circulation path and passes through the ball circulation path. The ball is returned to the starting point of the ball rolling path from the other end of the circulation path.
- the screw shaft and the nut can continuously move relative to each other.
- the endless ball path is composed of a ball rolling path and a ball circulation path. Therefore, if the circumferential length of the ball circulation path is long, the length of the ball rolling path is shortened accordingly. . If the length of the ball rolling path is short, the load capacity of the ball screw becomes small, which may adversely affect the life of the ball screw. Therefore, it has been desired to shorten the circumferential length of the ball circulation path.
- the “circumferential length of the ball circulation path” in the sixth embodiment means a circumferential distance between both ends of the ball circulation path, and the circumferential direction means a circumferential direction of the nut.
- a ball screw according to an aspect of the sixth embodiment includes a screw shaft having a helical thread groove on an outer peripheral surface, a nut having a screw groove facing the screw groove of the screw shaft on an inner peripheral surface, A ball screw comprising: a plurality of balls movably loaded in a spiral ball rolling path formed by both screw grooves; and a ball circulation path for circulating the ball from the end point of the ball rolling path to the starting point.
- the following three conditions A, B, and C are satisfied.
- the ball circulation path is constituted by a concave groove formed by concavely forming a part of the inner peripheral surface of the nut.
- Condition B the ball circulation path includes both end portions that are connection portions with the ball rolling path, an intermediate portion disposed between the both end portions, and a curved portion that connects the end portion and the intermediate portion. And is substantially S-shaped.
- Condition C The edge portion of the curved portion of the edge portion of the concave groove is curved, and the edge portion on the radially outer side of the curve has a shape in which a plurality of arcs having different curvature radii are smoothly continuous. Is formed.
- a ball screw according to another aspect of the sixth embodiment includes a screw shaft having a helical screw groove on the outer peripheral surface, and a nut having a screw groove facing the screw groove of the screw shaft on the inner peripheral surface;
- a ball comprising: a plurality of balls movably loaded in a spiral ball rolling path formed by the both screw grooves; and a ball circulation path for circulating the ball from the end point of the ball rolling path to the starting point.
- the screw is characterized in that the following three conditions D, E, and F are satisfied.
- Condition D The ball circulation path is constituted by a concave groove formed by concavely forming a part of the inner peripheral surface of the nut.
- Condition E The ball circulation path is composed of both end portions which are connecting portions with the ball rolling path, and two curved portions which are arranged between the both end portions and are curved in opposite directions, and are substantially S-shaped. I am doing.
- Condition F Of the edge of the concave groove, the edges of the two curved parts are curved, and the radially outer edge of the curve has a shape in which a plurality of arcs having different curvature radii are smoothly continuous. Is formed.
- a ball screw includes a screw shaft having a helical screw groove on the outer peripheral surface, and a nut having a screw groove facing the screw groove of the screw shaft on the inner peripheral surface.
- a plurality of balls that are slidably loaded in a spiral ball rolling path formed by the both screw grooves, and a ball circulation path that circulates the ball back from the end point of the ball rolling path to the starting point.
- the ball screw satisfies the following three conditions G, H, and I.
- Condition G The ball circulation path is constituted by a concave groove formed by concavely forming a part of the inner peripheral surface of the nut.
- Condition H The ball circulation path is composed of both end portions that are connected to the ball rolling path, and two curved portions that are arranged between the both end portions and bend in opposite directions, and are substantially S-shaped. I am doing.
- Condition I Of the edges of the concave groove, the edges of the two curved parts are curved, and the radially outer and radially inner edges of the curve are formed in a single arc shape. Has been.
- the concave groove constituting the ball circulation path is formed by forging.
- the length of the ball circulation path in the circumferential direction is short, and the length of the ball rolling path is increased accordingly, so that the load capacity is large and the life is long.
- FIG. 9 is a cross-sectional view (cross-sectional view cut along a plane along the axial direction) illustrating the structure of the ball screw of the first example of the sixth embodiment.
- the ball screw 1 has a screw shaft 3 having a helical thread groove 3 a on the outer peripheral surface and a helical screw groove 5 a facing the screw groove 3 a of the screw shaft 3 on the inner peripheral surface.
- a plurality of balls 9 movably loaded in a spiral ball rolling path 7 formed by the nut 5 and both screw grooves 3a, 5a, and the balls 9 are circulated back from the end point of the ball rolling path 7 to the starting point. And a ball circulation path 11 to be moved.
- the cross-sectional shape of the screw grooves 3a, 5a may be an arc shape (single arc shape) or a gothic arc shape.
- the material of the screw shaft 3, the nut 5, and the ball 9 is not particularly limited, and general materials can be used. For example, metal (steel etc.), sintered alloy, ceramic, and resin can be mentioned.
- the ball circulation path 11 will be described in detail with reference to cross-sectional views of FIGS. 10 and 11 (cross-sectional views cut along a plane orthogonal to the axial direction).
- the ball circulation path 11 is integrally formed on the inner peripheral surface of the nut 5. More specifically, the groove 22 formed by recessing a part of the cylindrical inner peripheral surface of the nut 5 by plastic working or cutting is used as the ball circulation path 11. Therefore, unlike the case of a ball circulation type such as a tube type or a piece type, no separate member constituting the ball circulation path is attached. And since another member is not used, there is no possibility that the step which has an edge part which arises in a boundary part when another member is used will arise.
- the ball 9 rolling to the end point of the ball rolling path 7 is scooped up from one end of the ball circulation path 11 and sinks into the nut 5 (radially outward). . Then, the ball passes through the ball circulation path 11, gets over the land portion 3 b of the screw shaft 3 (the thread of the screw groove 3 a), and returns to the starting point of the ball rolling path 7 from the other end of the ball circulation path 11.
- the cross-sectional shape of the ball circulation path 11 (the cross-sectional shape cut by a plane orthogonal to the longitudinal direction) may be an arc shape (single arc shape) or a gothic arc shape.
- the ball circulation path 11 (concave groove 22) has both ends 11a and 11a, which are connection portions with the ball rolling path 7 (screw groove 5a), in a straight line.
- An introductory portion of the ball 9 is formed by the end portion 11a having a shape.
- An intermediate portion 11b extending linearly is disposed between the both end portions 11a and 11a, and both ends of the intermediate portion 11b and the linear end portions 11a and 11a are respectively bent by the curved portions 11c and 11c.
- the ball circulation path 11 (concave groove 22) is generally S-shaped.
- the edge portion of the intermediate portion 11b and the edge portions of the both end portions 11a and 11a are linear, and the edge portions of the bending portions 11c and 11c are curved (curved lines).
- Shape The edge on the radially inner side of the curve is formed in a single arc shape (the radius of curvature is R1), and the edge on the radially outer side is two arcs with different curvature radii ( The radius of curvature R2 and R3) is formed in a smoothly continuous shape. Further, the curvature radius R2 of the arc on the end portion 11a side is set larger than the curvature radius R3 of the arc on the intermediate portion 11b side of the two arcs.
- the circumferential length L of the ball circulation path 11 (concave groove 22) is shorter than the circumferential length of the ball circulation path of the conventional ball screw.
- the circumferential length of the ball circulation path means a circumferential distance between both ends of the ball circulation path
- the circumferential direction means a circumferential direction of the nut.
- the ball circulation path of the conventional ball screw will be described with reference to FIG. In FIGS. 29, 30 and 31, the edge portion forming the outer periphery of the ball circulation path of the conventional ball screw is indicated by a two-dot chain line.
- symbol 304 of FIG. 32 shows a ball rolling path.
- the configuration of the ball circulation path (concave groove) in FIG. 32 is substantially the same as that of the ball circulation path 11 (concave groove 22) in FIG. 29, but only the shape of the edge on the radially outer side of the curved portion is different. . That is, in the conventional ball circulation path of the ball screw, the edge portion on the radially outer side of the curved portion 301 is formed in a single arc shape like the edge portion on the radially inner side. .
- the radius of curvature is R1 'on the radially inner side and R2' on the radially outer side.
- the circumferential length of the ball circulation path 11 (concave groove 22) of the ball screw 1 of the first example will be described. Since this is shorter than the circumferential length of the ball circulation path of the conventional ball screw, the ball rolling path 7 is formed longer in the endless ball path formed by the ball rolling path 7 and the ball circulation path 11. be able to. As a result, since the load capacity of the ball screw 1 of the first example is larger than that of the conventional ball screw, it has a long life. Moreover, the processing amount of the groove
- the ball circulation type is a top-type ball screw
- the position of the top due to the processing error of the top and nut top holes and the vibration of the ball screw
- the effect may not be sufficiently achieved due to a shift or the like.
- the ball circulation path 11 is formed integrally with the nut 5 in the ball screw 1 of the first example, the above-described effect due to the optimization of the shape of the ball circulation path 11 is sufficiently exhibited.
- the groove width tb of the intermediate portion 11b narrower than the groove width ta of the end portion 11a of the ball circulation path 11.
- the use of the ball screw 1 of the first example is not particularly limited, but can be suitably used for automobile parts, positioning devices and the like.
- the number of arcs constituting the radially outer edge is two, but the number is not limited to two and may be three or more.
- the center of curvature of the arc that forms the radially inner edge of the curved portion 11c and the center of curvature of the two arcs that form the radially outer edge. May be the same center of curvature.
- the columnar steel material 20 was processed by plastic working such as cold forging to obtain a blank 21 having substantially the same shape (substantially cylindrical shape) as the nut 5 (rough forming step).
- the flange 13 is also formed on the outer peripheral surface of the blank 21 by plastic working.
- a part of the cylindrical inner peripheral surface of the blank 21 is recessed by plastic working such as cold forging (or may be cutting), and the ball circulation connects the end point and the start point of the ball rolling path 7.
- a substantially S-shaped concave groove 22 forming the path 11 was formed (ball circulation path forming step).
- the ball circulation path 11 (concave groove 22) is complicated as described above (particularly the shape of the edge of the curved portion 11c), the above-described ball circulation path forming step is performed by plastic working, so that the cutting process is performed. It can be processed easily and inexpensively. Further, if the groove width of the ball circulation path 11 (concave groove 22) differs depending on the part as described above, it is difficult to form by cutting, but if it is plastic working, it can be easily formed only by producing a die. can do. Therefore, the ball screw 1 of the first example of the sixth embodiment has high productivity.
- the method for forming the concave groove 22 include the following. That is, a mold (not shown) having a convex portion corresponding to the concave groove 22 is inserted into the blank 21, the convex portion of the mold is brought into contact with the inner peripheral surface of the blank 21, and the inner periphery of the blank 21 is
- the groove 22 can be formed by plastic working by strongly pressing the mold toward the surface.
- the groove 22 may be formed by using a cam mechanism mold having a cam driver and a cam slider having a convex portion corresponding to the groove 22. More specifically, a cam driver and a cam slider are inserted into the blank 21. At that time, the cam slider is disposed between the blank 21 and the cam driver, and the convex portion is disposed toward the inner peripheral surface of the blank 21. The cam slider and the cam driver arranged in the blank 21 are in contact with each other at an inclined surface extending in a substantially axial direction of the blank 21 (a direction slightly inclined from the axial direction of the blank 21). A cam mechanism is configured.
- the cam slider moves outward in the radial direction of the blank 21 by the cam mechanism (wedge action) constituted by both inclined surfaces. That is, a force is transmitted from the inclined surface of the cam driver to the inclined surface of the cam slider, and the axial force of the cam driver is converted into a force that moves the cam slider radially outward.
- the convex portion of the cam slider strongly presses the inner peripheral surface of the blank 21, so that the concave groove 22 is formed on the inner peripheral surface of the blank 21 by plastic working.
- the method shown in FIG. 26 may be used instead of the method shown in FIG.
- the thread groove 5a was formed in the inner peripheral surface of the nut 5 so as to be connected to the endmost part of the ball circulation path 11 (concave groove 22) by a conventional cutting process (for example, the method shown in FIG. 24) ( Thread groove forming step).
- a conventional cutting process for example, the method shown in FIG. 24
- Thread groove forming step since the outermost end portion of the concave groove 22 (ball circulation path 11) has a spherical shape, an edge portion as in the case of a piece type ball screw is not generated at the step of the boundary portion 30 with the screw groove 5a. It becomes a smooth step. As a result, even if the ball 9 passes through the boundary portion 30, abnormal noise and operating torque fluctuations are less likely to occur, and the lifetime is not likely to decrease.
- heat treatment such as quenching and tempering was performed under desired conditions, and the nut 5 was obtained.
- the heat treatment include carburizing treatment, carbonitriding treatment, and high-frequency heat treatment.
- the material of the nut 5 is preferably chromium steel or chromium molybdenum steel (for example, SCM420) having a carbon content of 0.10 to 0.25% by mass
- carbon steel having a carbon content of 0.4 to 0.6% by mass for example, S53C, SAE4150 is preferable.
- the ball screw 1 was manufactured by combining the nut 5 manufactured in this way, the screw shaft 3 and the ball 9 manufactured by a conventional method. Since the rough forming step and the ball circulation path forming step described above are performed by plastic working, the manufacturing method of the ball screw 1 can manufacture a high-precision ball screw at a low cost in addition to a high material yield. Can do. Moreover, since it manufactures by plastic processing, since the metal flow (forged streamline) which the steel raw material 20 has is hardly cut
- the type of plastic working is not particularly limited, but forging is preferable, and cold forging is particularly preferable. Although hot forging can be used, cold forging can finish with higher accuracy than hot forging, so it is possible to obtain a sufficiently accurate nut 5 without post-processing. Can do. Therefore, the ball screw 1 can be manufactured at low cost.
- the plastic working in the rough forming step and the ball circulation path forming step is preferably cold forging, but the plastic working in any one step may be cold forging.
- FIG. 30 is a view for explaining the structure of the ball screw of the second example of the sixth embodiment, and is a view showing a groove on the inner peripheral surface of the nut.
- the structure and effect of the ball screw of the second example are almost the same as those of the first example, only different parts will be described, and description of the same parts will be omitted.
- the same or corresponding parts as those in FIG. 29 are denoted by the same reference numerals as those in FIG.
- the ball circulation path 11 (concave groove 22) is linear at both ends 11a and 11a, which are connection parts with the ball rolling path 7 (screw groove 5a).
- An introduction portion for the ball 9 is formed by the linear end portion 11a.
- the both end portions 11a and 11a are smoothly connected by two curved portions 11c and 11c that are curved in opposite directions, and the overall shape of the ball circulation path 11 (concave groove 22) is substantially S-shaped. ing. That is, it differs from the first example in that it does not have a linear intermediate portion.
- edges forming the outer periphery of the concave groove 22 are linear, and the edges of the curved portions 11c, 11c are curved (curved). Then, the radially inner edge and the radially outer edge of the curve are each formed in a shape in which two circular arcs having different curvature radii are smoothly continuous.
- the radius of curvature of the arc that forms the radially inner edge is R1 and R2
- the radius of curvature of the arc that configures the radially outer edge is R3 and R4.
- the two arcs constituting the radially outer edge of the bending portion 11c are an arc on the end portion 11a side and an arc on the other bending portion 11c side.
- the radius of curvature R3 of the arc on the end 11a side is set larger than the radius of curvature R4 of the arc.
- the edge portion on the radially inner side may be formed in a single arc shape as in the first example. With such a configuration, the circumferential length L of the ball circulation path 11 (concave groove 22) is shorter than that in the first example. Further, the change in the traveling direction of the ball 9 traveling in the ball circulation path 11 is also gentler than in the first example.
- FIG. 31 is a view for explaining the structure of the ball screw of the third example of the sixth embodiment, and is a view showing a groove on the inner peripheral surface of the nut.
- the ball circulation path 11 (concave groove 22) has both end portions 11a and 11a that are connected to the ball rolling path 7 (screw groove 5a) in a straight line.
- An introduction portion for the ball 9 is formed by the linear end portion 11a.
- the both end portions 11a and 11a are smoothly connected by two curved portions 11c and 11c that are curved in opposite directions, and the overall shape of the ball circulation path 11 (concave groove 22) is substantially S-shaped. ing. That is, it differs from the first example in that it does not have a linear intermediate portion.
- the edge portions forming the outer periphery of the concave groove 22 are linear, and the edge portions of the curved portions 11c and 11c are curved (curved). Then, the radially inner edge and the radially outer edge of the curve are each formed in a single arc shape.
- the radius of curvature of the arc that forms the edge on the radially inner side is R1
- the radius of curvature of the arc that forms the edge on the radially outer side is R2.
- first to third examples are examples of the sixth embodiment, and the sixth embodiment is not limited to the first to third examples.
- a nut circulation type ball screw in which a ball circulation path 11 for circulating the ball 9 from the end point of the ball rolling path 7 to the start point is formed in the nut 5 is illustrated.
- the sixth embodiment can also be applied to a screw shaft circulation type ball screw in which a screw shaft corresponding to the ball circulation path 11 is formed.
- the seventh embodiment relates to a ball screw.
- the ball screw is a spiral ball rolling path formed by a screw shaft having a helical thread groove on the outer peripheral surface, a nut having a screw groove facing the screw groove of the screw shaft on the inner peripheral surface, and both screw grooves. And a plurality of balls loaded in a rollable manner. Then, when the nut and the screw shaft that are screwed to the screw shaft through the ball are relatively rotated, the screw shaft and the nut are relatively moved in the axial direction through the rolling of the ball. .
- Such a ball screw is provided with a ball circulation path that forms an endless ball path by connecting the start point and end point of the ball rolling path. That is, the ball moves around the screw shaft while moving in the ball rolling path and reaches the end point of the ball rolling path. The ball is scooped up from one end of the ball circulation path and passes through the ball circulation path. The ball is returned to the starting point of the ball rolling path from the other end of the circulation path.
- the screw shaft and the nut can continuously move relative to each other.
- Patent Document 14 discloses a ball screw in which an oil sump is provided in a ball rolling path of a resin nut manufactured by an injection molding method. That is, a concave portion constituting an oil reservoir is formed on the surface of the thread groove of the nut, and the lubricant is filled in the oil reservoir.
- the seventh embodiment provides a ball screw that improves the lubricity without solving the problems of the prior art as described above, and without reducing the load capacity and life and increasing the manufacturing cost. Let it be an issue.
- the seventh embodiment has the following configuration. That is, the ball screw of the seventh embodiment includes a screw shaft having a helical screw groove on the outer peripheral surface, a nut having a screw groove on the inner peripheral surface facing the screw groove of the screw shaft, and the both screw grooves. A plurality of balls that are movably loaded in a spiral ball rolling path that is formed, and a ball circulation path that circulates the ball from the end point of the ball rolling path to the start point.
- the ball screw formed by a concave groove formed by recessing a part of the inner peripheral surface of the nut includes a lubricant reservoir capable of holding a lubricant, and the lubricant reservoir is provided in the concave groove. It consists of a recessed part formed by making a part of inner surface of this concave.
- the ball circulation path includes both end portions that are connection portions with the ball rolling path and an intermediate portion between the both end portions.
- the area of the cross section of the lubricant reservoir cut along a plane orthogonal to the longitudinal direction is preferably larger in the portion adjacent to the intermediate portion than in the portion adjacent to the end portion.
- the ball circulation path is curved, and is disposed on the radially inner side of the curvature of the ball circulation path rather than the lubricant reservoir disposed on the radially outer side of the curvature of the ball circulation path.
- the lubricant reservoir preferably has a larger cross-sectional area cut by a plane orthogonal to the longitudinal direction of the ball circulation path.
- the concave groove constituting the ball circulation path and the concave part constituting the lubricant reservoir are simultaneously formed by forging.
- the ball screw according to the seventh embodiment is provided with a lubricant reservoir in the ball circulation path of the nut, thereby realizing excellent lubricity without being accompanied by a decrease in load capacity and life and an increase in manufacturing cost.
- FIG. 9 is a cross-sectional view (cross-sectional view cut along a plane along the axial direction) illustrating the structure of the ball screw of the first example of the seventh embodiment.
- the ball screw 1 has a screw shaft 3 having a helical thread groove 3 a on the outer peripheral surface and a helical screw groove 5 a facing the screw groove 3 a of the screw shaft 3 on the inner peripheral surface.
- a plurality of balls 9 movably loaded in a spiral ball rolling path 7 formed by the nut 5 and both screw grooves 3a, 5a, and the balls 9 are circulated back from the end point of the ball rolling path 7 to the starting point. And a ball circulation path 11 to be moved.
- the cross-sectional shape of the thread grooves 3a and 5a may be an arc shape (single arc shape) or a gothic arc shape.
- the material of the screw shaft 3, the nut 5, and the ball 9 is not particularly limited, and general materials can be used. For example, metal (steel etc.), sintered alloy, ceramic, and resin can be mentioned.
- the ball circulation path 11 will be described in detail with reference to cross-sectional views of FIGS. 10 and 11 (cross-sectional views cut along a plane orthogonal to the axial direction).
- the ball circulation path 11 is formed integrally with the inner peripheral surface of the nut 5, for example. More specifically, the groove 22 formed by recessing a part of the cylindrical inner peripheral surface of the nut 5 by plastic working or cutting is used as the ball circulation path 11. Therefore, unlike the case of a ball circulation type such as a tube type or a piece type, no separate member constituting the ball circulation path is attached. And since another member is not used, there is no possibility that the step which has an edge part which arises in a boundary part when another member is used will arise.
- the ball 9 rolling to the end point of the ball rolling path 7 is scooped up from one end of the ball circulation path 11 and sinks into the nut 5 (radially outward). . Then, the ball passes through the ball circulation path 11, gets over the land portion 3 b of the screw shaft 3 (the thread of the screw groove 3 a), and returns to the starting point of the ball rolling path 7 from the other end of the ball circulation path 11.
- the cross-sectional shape of the ball circulation path 11 may be an arc shape (single arc shape) or a gothic arc shape.
- both ends of the concave groove 22 constituting the ball circulation path 11 are connected to the ball rolling path 7 (screw groove 5a) in a straight line.
- the intermediate portion 24 located between them has a curved shape curved in a substantially S shape.
- bowl 9 is formed in the linear edge part, and the extreme end part of the linear edge part has comprised circular arc shape.
- groove 22 is not limited to substantially S shape as shown in FIG.
- the nut 5 is provided with a lubricant reservoir capable of holding a lubricant.
- This lubricant reservoir consists of a recess 31 formed by recessing a part of the inner surface of the groove 22 (see FIG. 34).
- Lubricants such as grease and lubricating oil are held in the lubricant reservoir and appropriately supplied to the ball circulation path 11 during use of the ball screw 1.
- the lubricant adheres to the surface of the ball 9 in the ball circulation path 11, reaches the ball rolling path 7 together with the ball 9, and is used for lubrication of the screw grooves 3 a, 5 a and the surface of the ball 9. Is excellent in lubricity.
- the ball screw 1 is lubricated by the lubricant held in the lubricant reservoir, the frequency of maintenance work for supplying the lubricant to the inside of the ball screw 1 can be reduced.
- the portion where the recess 31 is formed is not particularly limited as long as it is the inner surface of the recess groove 22.
- the curved portion of the substantially S-shaped intermediate portion 24 and the arc-shaped outermost portion are formed. It is good to form in the site
- the nut inner peripheral surface side of the recessed part 31 may be open
- the inner peripheral surface of the nut 5 may be recessed to form the recessed portion 31 that is continuous with the recessed groove 22.
- the concave portion 31 is smoothly connected to the concave groove 22. That is, as can be seen from the cross-sectional view of FIG. 34, the surface of the nut 5 is smoothly continuous from the inner peripheral surface of the nut 5 to the concave groove 22 via the concave portion 31 while the curvature gradually changes. Therefore, the lubricant in the concave portion 31 is easily supplied into the concave groove 22. Further, the depth of the concave portion 31 (the length in the radial direction of the nut 5) is deepest at the center in the longitudinal direction of the concave portion 31, but the depth is the radius of curvature of the concave groove 22 in any portion. It is smaller than (1/2 of the groove width t of the intermediate portion 24).
- the ball 9 that has entered the ball circulation path 11 from the ball rolling path 7 is guided by hitting the curved portion of the intermediate section 24 through the introduction section 25 and changes the traveling direction.
- the concave portion 31 is not formed on the radially outer side of the curved portion (that is, the portion where the ball 9 abuts) among the introduction portion 25 and the curved portion of the ball circulation path 11,
- the circulation property (guidance performance of the ball 9) of the circulation path 11 does not deteriorate.
- the recessed part 31 may be provided in the radial direction outer side of the curve of the ball circulation path 11, it is preferable from a viewpoint similar to the above that it is smaller than the recessed part 31 provided in the radial direction inner side of the curve. More specifically, assuming that the lubricant reservoir (concave portion 31) is cut along a plane orthogonal to the longitudinal direction of the ball circulation path 11 (concave groove 22), the area of the cross section is the radial direction of the curvature of the ball circulation path 11 It is preferable that the concave portion 31 provided on the radially outer side of the curve is smaller than the concave portion 31 provided on the inner side.
- the ball screw 1 of the first example has excellent lubricity. Further, since the lubricant reservoir is formed not in the ball rolling path 7 but in the ball circulation path 11, the load capacity and life of the ball screw 1 are not reduced.
- the use of the ball screw 1 of the first example is not particularly limited, but can be suitably used for automobile parts, positioning devices and the like.
- the columnar steel material 20 was processed by plastic working such as cold forging to obtain a blank 21 having substantially the same shape (substantially cylindrical shape) as the nut 5 (rough forming step).
- the flange 13 is also formed on the outer peripheral surface of the blank 21 by plastic working.
- a part of the cylindrical inner peripheral surface of the blank 21 is recessed by plastic working such as cold forging (or may be cutting), and the ball circulation connects the end point and the start point of the ball rolling path 7.
- a substantially S-shaped concave groove 22 forming the path 11 was formed (ball circulation path forming step).
- the recess 31 constituting the oil reservoir was formed by plastic working (or cutting work).
- the method for forming the concave groove 22 and the concave portion 31 include the following. That is, a mold (not shown) having a convex portion having a shape corresponding to the concave groove 22 and another convex portion having a shape corresponding to the concave portion 31 is inserted into the blank 21, and is formed on the inner peripheral surface of the blank 21.
- the concave grooves 22 and the concave portions 31 can be formed by bringing the both convex portions of the mold into contact with each other and pressing the mold strongly toward the inner peripheral surface of the blank 21 for plastic processing.
- the concave groove 22 and the concave portion 31 may be formed separately, but if they are formed simultaneously in one step as described above, the manufacturing cost of the ball screw 1 can be kept low.
- a cam mechanism mold having a cam driver and a cam slider having a convex portion having a shape corresponding to the concave groove 22 and another convex portion having a shape corresponding to the concave portion 31.
- the groove 22 and the recess 31 may be formed by using them. More specifically, a cam driver and a cam slider are inserted into the blank 21. At that time, the cam slider is disposed between the blank 21 and the cam driver, and both convex portions are disposed toward the inner peripheral surface of the blank 21.
- the cam slider and the cam driver arranged in the blank 21 are in contact with each other at an inclined surface extending in a substantially axial direction of the blank 21 (a direction slightly inclined from the axial direction of the blank 21).
- a cam mechanism is configured.
- the thread groove 5a was formed in the inner peripheral surface of the nut 5 so as to be connected to the endmost part of the ball circulation path 11 (concave groove 22) by a conventional cutting process (for example, the method shown in FIG. 24) ( Thread groove forming step).
- a conventional cutting process for example, the method shown in FIG. 24
- Thread groove forming step since the outermost end portion of the concave groove 22 (ball circulation path 11) has a spherical shape, an edge portion as in the case of a piece type ball screw is not generated at the step of the boundary portion 30 with the screw groove 5a. It becomes a smooth step. As a result, even if the ball 9 passes through the boundary portion 30, abnormal noise and operating torque fluctuations are less likely to occur, and the lifetime is not likely to decrease.
- heat treatment such as quenching and tempering was performed under desired conditions, and the nut 5 was obtained.
- the heat treatment include carburizing treatment, carbonitriding treatment, and high-frequency heat treatment.
- the material of the nut 5 is preferably SCM420, and when the heat treatment is induction hardening, it is preferably S53C or SAE4150.
- the ball screw 1 was manufactured by combining the nut 5 manufactured in this way, the screw shaft 3 and the ball 9 manufactured by a conventional method. Since the rough forming step and the ball circulation path forming step described above are performed by plastic working, the manufacturing method of the ball screw 1 can manufacture a high-precision ball screw at a low cost in addition to a high material yield. Can do. Moreover, since it manufactures by plastic processing, since the metal flow (forged streamline) which the steel raw material 20 has is hardly cut
- the type of plastic working is not particularly limited, but forging is preferable, and cold forging is particularly preferable. Although hot forging can be used, cold forging can finish with higher accuracy than hot forging, so it is possible to obtain a sufficiently accurate nut 5 without post-processing. Can do. Therefore, the ball screw 1 can be manufactured at low cost.
- the plastic working in the rough forming step and the ball circulation path forming step is preferably cold forging, but the plastic working in any one step may be cold forging.
- FIGS. 35 to 37 are views for explaining the structure of the ball screw of the second example of the seventh embodiment.
- FIG. 35 is a view showing the grooves and recesses on the inner peripheral surface of the nut
- FIGS. 36 and 37 are cross-sectional views of the grooves and recesses in FIG.
- the same or corresponding parts as those in FIGS. 9 to 11 and FIGS. 33 and 34 are denoted by the same reference numerals as those in FIGS.
- the portion for forming the recess 31 is formed in a portion along the introduction portion 25 and the intermediate portion 24 in the edge portion of the recess groove 22 as shown in FIG. 35).
- the recess 31 is formed so that the portion along the intermediate portion 24 is larger than the portion along the introduction portion 25. More specifically, assuming that the lubricant reservoir (concave portion 31) is cut in a plane perpendicular to the longitudinal direction of the ball circulation path 11 (concave groove 22), the area of the cross section is small at the portion along the introduction portion 25, The portion along the intermediate portion 24 is larger than that.
- the cross-sectional area of the portion along the introduction portion 25 is the smallest, the cross-sectional area gradually increases as it approaches the longitudinal center of the recess 31, and the cross-sectional area is largest at the longitudinal center of the recess 31.
- the depth of the recess 31 (the length in the radial direction of the nut 5) is deepest at the center in the longitudinal direction of the recess 31, but the depth is the radius of curvature of the groove 22 in any portion. It is smaller than (1/2 of the groove width t of the intermediate portion 24). Furthermore, the ball 9 that has entered the ball circulation path 11 from the ball rolling path 7 is guided by hitting the curved portion of the intermediate section 24 through the introduction section 25 and changes the traveling direction. Since the ball 9 also hits the introduction portion 25, as can be seen from FIG. 37, the radially outer side (left side in FIG. 37) is more radially outward than the radially inner side (right side in FIG. 37). A recess 31 having a small cross-sectional area is formed. Therefore, the circulation property (guide performance of the ball 9) of the ball circulation path 11 is hardly deteriorated.
- FIG. 38 is a view for explaining the structure of the ball screw of the third example of the seventh embodiment, and is a view showing a groove and a recess on the inner peripheral surface of the nut.
- the structure and effect of the ball screw of the third example are substantially the same as those of the first example and the second example, only different parts will be described and description of the same parts will be omitted.
- the concave portion 31 is formed along the entire edge of the concave groove 22 (shaded portion in FIG. 38).
- the area of the cross section when it is assumed that the lubricant reservoir (recess 31) is cut in a plane orthogonal to the longitudinal direction of the ball circulation path 11 (recess groove 22) is any part of the lubricant reservoir (recess 31).
- the concave portion 31 is uniformly formed along the entire edge of the concave groove 22. Since the lubricant reservoir is formed up to the extreme end (arc-shaped portion) of the concave groove 22, more lubricant can be held in the lubricant reservoir. Therefore, the lubricity of the ball screw 1 is more excellent.
- the first to third examples show an example of the seventh embodiment, and the seventh embodiment is not limited to the first to third examples.
- a nut circulation type ball screw in which a ball circulation path 11 for circulating the ball 9 from the end point of the ball rolling path 7 to the start point is formed in the nut 5 is illustrated.
- the seventh embodiment is also applicable to a screw shaft circulation type ball screw in which a screw shaft corresponding to the ball circulation path 11 is formed.
- the cross-sectional shape of the concave portion 31 constituting the lubricant reservoir is not limited to the circular arc shape as shown in FIGS. 34, 36, and 37, and a plurality of circular arcs having different curvature radii may be smoothly continuous. It may be oval or substantially triangular. In the case of a substantially triangular shape, the concave groove 22 and the concave portion 31 are smoothly connected. Furthermore, the concave groove 22 and the concave portion 31 may be smoothly connected by a convex portion having a circular arc shape in cross section. Furthermore, the lubricant reservoir may be a convex portion having an arcuate cross section as in the first embodiment.
- the ball screw shown in each example of each said embodiment can be applied with respect to the ball screw shown in other embodiment.
- the ball circulation groove in each of the embodiments is not limited to the forging shown in FIGS. 22 and 26 described above, and may be formed by other plastic processing, removal processing such as cutting processing and electric discharge processing.
- general heat treatment conditions including the heat treatment conditions described in the other embodiments can be applied without any problem.
- FIG. 39 is a partial cross-sectional view of the steering gear of the electric power steering apparatus.
- a rack and pinion housing 621 constituting the steering gear case is provided with a rack shaft 623 constituting a rack and pinion mechanism and a pinion (not shown), and the pinion is connected to the lower shaft 622.
- a rack 625 that meshes with a pinion is formed on the left side of the drawing, and spherical joints 627 that support a tie rod 615 in a swingable manner are fixed to both ends.
- the screw shaft of the ball screw is used for the rack shaft 623.
- a ball screw housing 633 is attached to the right end of the rack and pinion housing 621 in the figure.
- the ball screw housing 633 accommodates a drive gear 637 fixed to the shaft of the electric motor 635 and a driven gear 639 engaged with the drive gear 637 at the lower end thereof, with the front end of the electric motor 635 fixed by bolts. ing.
- a ball nut 645 is rotatably held in the ball screw housing 633 via a double row angular ball bearing.
- the ball nut 645 is accommodated in the inner diameter of the driven gear 639.
- a spline fitting portion 661 is provided between the inner diameter side of the driven gear 639 and the outer diameter side of the ball nut 645.
- a male ball screw groove (thread portion) 651 is formed on the right side of the rack shaft 623 in the figure.
- a female ball screw groove 653 is formed in the ball nut 645, and a large number of steel balls 655 constituting a circulation ball are interposed between the male ball screw groove 651 and the female ball screw groove 653. Yes.
- the ball nut 645 is provided with a circulation groove (not shown) for circulating the steel ball 655.
- the steering wheel when the steering wheel is steered by the driver, the steering force is transmitted from the lower shaft 622 to the pinion, and the rack shaft 623 is attached to any one of the left and right in the figure along with the rack 625 engaged therewith.
- the steered wheels are steered through the left and right tie rods.
- the electric motor 635 rotates with a predetermined rotational torque in either the forward or reverse direction, and the rotational torque is transmitted to the ball nut 645 via the drive gear 637 and the driven gear 639.
- a thrust force acts on the male ball screw groove 651 of the rack shaft 623 via the steel ball 655 engaged with the female ball screw groove 653, thereby expressing the steering assist torque.
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Abstract
Description
ボール戻し経路を用いたボールの循環方式には循環チューブ方式やコマ方式などがあり、コマ方式の場合は、ボール戻し経路をなす凹部(溝状のボール戻し経路)が形成されたコマをナットの貫通穴に嵌めている。これに対して、溝状のボール戻し経路(「ボール循環溝」と称されることが多い)がナットの内周面に直接形成されていれば、組み付けの手間やコストが低減できるとともに、ボール循環の信頼性向上も期待できる。
特許文献2には、ナットの軸方向一端部に、ナットと一体に同軸の円環状のボール循環部を設け、このボール循環部にボール循環溝を設けることが記載されている。
この発明の課題は、溝状のボール戻し経路(ボール循環溝)を有するボールねじの耐久性、ボール循環性能、および加工性能を更に向上させることである。
さらに、本発明の第3の態様に係るボールねじは、第2の態様に係るボールにおいて、潤滑剤を保持可能な潤滑剤溜まりを備えており、該潤滑剤溜まりは、前記凹溝の内面の一部を凹化させてなる凹部からなることを特徴とする。
さらに、本発明の第7の態様に係るボールねじは、第2の態様に係るボールにおいて、前記ボール循環溝の表面の算術平均粗さRa2 が0μm超1.6μm以下であることを特徴とする。
さらに、本発明の第11の態様に係るボールねじは、第2の態様に係るボールにおいて、前記ナットは、前記ボール循環溝と前記ボール転走路との境界部分にブラシ加工及びブラスト加工の少なくとも一方を施してバリを除去することにより形成されたものであることを特徴とする。
条件A:前記ボール循環溝は、前記ナットの内周面の一部を凹化させて形成した凹溝で構成されている。
条件B:前記ボール循環溝は、前記ボール転走路との接続部分である両端部と、前記両端部の間に配された中間部と、前記端部と前記中間部とを接続する湾曲部と、からなり、略S字状をなしている。
さらに、本発明の第13の態様に係るボールねじは、第2の態様に係るボールにおいて、前記ボール循環溝は、前記ボール転走路との接続部分である両端部と、前記両端部の間に配された中間部と、を備えており、前記端部の溝幅よりも前記中間部の溝幅の方が狭いことを特徴とする。
条件D:前記ボール循環溝は、前記ナットの内周面の一部を凹化させて形成した凹溝で構成されている。
条件E:前記ボール循環溝は、前記ボール転走路との接続部分である両端部と、前記両端部の間に配され互いに逆方向に湾曲する2つの湾曲部と、からなり、略S字状をなしている。
さらに、本発明の第15の態様に係るボールねじは、第2の態様に係るボールにおいて、下記の3つの条件G,H,Iを満足することを特徴とする。
条件H:前記ボール循環溝は、前記ボール転走路との接続部分である両端部と、前記両端部の間に配され互いに逆方向に湾曲する2つの湾曲部と、からなり、略S字状をなしている。
さらに、本発明の第16の態様に係るボールねじは、第2の態様に係るボールにおいて、前記ボール循環溝は、前記ナットの内周面の一部を凹化させて形成した凹溝で構成されており、前記ボール循環溝の長手方向の少なくとも一部分は、前記長手方向に直交する平面で切断した場合の断面形状が略V字状をなしていることを特徴とする。
さらに、本発明の第18の態様に係るボールねじは、第16の態様に係るボールにおいて、前記ボール循環溝を構成する凹溝の底部に潤滑剤溜まりを設けたことを特徴とする。
〔第1実施形態〕
図1~3に示すように、第1実施形態の第1例のボールねじは、ねじ軸201と、ナット202と、ボール203と、コマ204を備えている。ねじ軸201の外周面に螺旋溝201aが形成されている。ナット202の内周面に螺旋溝202aが形成されている。ナット202の径方向に貫通する貫通穴202bにコマ204が嵌めてある。ボール203は、ナット202の螺旋溝202aとねじ軸201の螺旋溝201aで形成される軌道の間に配置されている。
図5に示すように、ナット202の内周面202dに形成されたボール循環溝241は、溝底241aと、溝底241aに連続する1対の側面241bを有する。ボール循環溝241の両側面241bと各側面241bに連続する軸方向に延びる面(ナット202の内周面)202dとの角部241cが、丸く形成されている。
また、ボール循環溝241を進行するボール203が、ねじ軸1の外周面(ランド部)201bを超える際にもスムーズに移動できるため、ボール循環性能が向上する。さらに、ボール循環溝241の角部241cが丸く形成されていることにより、角部241cにバリがほとんど発生しない。よって、バリ取りの後工程が省略できるため、加工性能が向上する。
また、特許文献3のように、循環溝(ボール循環溝)のボール進行方向に直交する、溝底と一対の側面を有する断面形状を、溝底から離れる方向に向けて側面が広がる形状とした上で、このボール循環溝の両側面と各側面に連続する軸方向に延びる面との角部を丸く形成してもよい。これにより、ボールねじの耐久性、ボール循環性能、および加工性能を更に向上できる。
また、ボール循環溝がナットではなく、ねじ軸に形成されている場合にも、このボール循環溝の両側面と各側面に連続する軸方向に延びる面との角部を丸く形成することによって、同様の効果を得ることができる。
第2実施形態は、ボールねじに関する。
ボールねじは、螺旋状のねじ溝を外周面に有するねじ軸と、ねじ軸のねじ溝に対向するねじ溝を内周面に有するナットと、両ねじ溝により形成される螺旋状のボール転走路内に転動自在に装填された複数のボールと、からなる。そして、ボールを介してねじ軸に螺合されているナットとねじ軸とを相対回転運動させると、ボールの転動を介してねじ軸とナットとが軸方向に相対移動するようになっている。
このようなボールねじにおけるボール循環路の形状としては、例えば特許文献3に開示されているように、ボール循環路の長手方向に直交する平面で切断した場合の断面形状が略U字状のものが知られている。
そこで、第2実施形態は、上記のような従来技術が有する問題点を解決し、製造時に必要なエネルギーが小さいボールねじを提供することを課題とする。
第2実施形態のボールねじは、ボール循環路の長手方向の少なくとも一部分は、前記長手方向に直交する平面で切断した場合の断面形状が略V字状をなしているので、製造時に必要なエネルギーが小さい。
[第1例]
図9は、第2実施形態の第1例のボールねじの構造を説明する断面図(軸方向に沿う平面で切断した断面図)である。
図9に示すように、ボールねじ1は、螺旋状のねじ溝3aを外周面に有するねじ軸3と、ねじ軸3のねじ溝3aに対向する螺旋状のねじ溝5aを内周面に有するナット5と、両ねじ溝3a,5aにより形成される螺旋状のボール転走路7内に転動自在に装填された複数のボール9と、ボール9をボール転走路7の終点から始点へ戻し循環させるボール循環路11と、を備えている。
なお、ねじ溝3a,5aの断面形状(長手方向に直交する平面で切断した場合の断面の形状)は、円弧状(単一円弧状)でもよいしゴシックアーク状でもよい。また、ねじ軸3,ナット5,及びボール9の材質は特に限定されるものではなく、一般的な材料を使用可能である。例えば、金属(鋼等),焼結合金,セラミック,樹脂があげられる。
また、図12に示すように、ボール循環路11(凹溝22)は、ボール転走路7(ねじ溝5a)との接続部分である両端部11a,11aが直線状となっており、両端部11a,11aの間に位置する中間部11bが曲線状となっている。この中間部11bの両端と両端部11a,11aとが滑らかに接続されていて、図10のA矢視方向から見たボール循環路11(凹溝22)の全体形状は略S字状をなしている。ただし、ボール循環路11の全体形状は、図12に示すような略S字状に限定されるものではない。
さらに、ボール循環路11の断面形状がV字状であるため、ボール循環路11を構成する凹溝22の底部に、凹溝22の内面とボール9とに囲まれた空間が形成される。この空間には、潤滑油,グリース等の潤滑剤を保持可能なので、該空間は潤滑剤溜まりとして機能する。
このような第1例のボールねじ1の用途は特に限定されるものではないが、自動車部品,位置決め装置等に好適に使用可能である。
次に、ブランク21の円柱面状の内周面の一部を冷間鍛造等の塑性加工により凹化させて、ボール転走路7の終点と始点を連通するボール循環路11をなす略S字状の凹溝22を形成した(ボール循環路形成工程)。
なお、前述の粗成形工程及びボール循環路形成工程を塑性加工で行ったので、このボールねじ1の製造方法は、材料歩留まりが高いことに加えて、高精度のボールねじを安価に製造することができる。また、塑性加工により製造するため、鋼製素材20が有するメタルフロー(鍛流線)がほとんど切断されず、また、加工硬化するので、高強度のナット5が得られる。
第2実施形態の第2例のボールねじの構成及び作用効果は、第1例とほぼ同様であるので、異なる部分のみ説明し、同様の部分の説明は省略する。
第1例のボールねじ1においては、ボール循環路11の断面形状は、長手方向全体でV字状をなしているが、ボール循環路11の一部分(ボール循環路11の長手方向の一部分)の断面形状がV字状であってもよい。第2例のボールねじ1においては、中間部11bのみが断面V字状となっており、両端部11a,11aの断面形状は、円弧状(単一円弧状)又はゴシックアーク状となっている。鍛造時の除肉量が最も多い中間部11bが断面V字状となっているので、鍛造に要するエネルギーが大幅に小さくなる。
第2実施形態の第3例のボールねじの構成及び作用効果は、第1例とほぼ同様であるので、異なる部分のみ説明し、同様の部分の説明は省略する。
第3例のボールねじ1においては、第2例の場合とは逆に、両端部11a,11aが断面V字状となっており、中間部11bの断面形状は円弧状(単一円弧状)又はゴシックアーク状となっている。
また、ボール9が滑りによって移動する中間部11bの断面形状を、ボール9が凹溝22の内面と1点で接触する円弧状又は略U字状とすれば、ボール9の摩耗損失を低減することができる。
第3実施形態は、ボールねじの製造方法に関する。
ボールねじは、螺旋状のねじ溝を外周面に有するねじ軸と、ねじ軸のねじ溝に対向するねじ溝を内周面に有するナットと、両ねじ溝により形成される螺旋状のボール転走路内に転動自在に装填された複数のボールと、からなる。そして、ボールを介してねじ軸に螺合されているナットとねじ軸とを相対回転運動させると、ボールの転動を介してねじ軸とナットとが軸方向に相対移動するようになっている。
そこで、第3実施形態は、上記のような従来技術が有する問題点を解決し、異音や作動トルク変動が生じにくく長寿命で安価なボールねじの製造方法を提供することを課題とする。
この第3実施形態のボールねじの製造方法は、ボール循環路とボール転走路との境界部分に生じるバリを除去するバリ除去工程を備えているので、境界部分をボールが通過する際に異音や作動トルク変動が生じにくく長寿命なボールねじを安価に製造することができる。
図9に示すように、ボールねじ1は、螺旋状のねじ溝3aを外周面に有するねじ軸3と、ねじ軸3のねじ溝3aに対向する螺旋状のねじ溝5aを内周面に有するナット5と、両ねじ溝3a,5aにより形成される螺旋状のボール転走路7内に転動自在に装填された複数のボール9と、ボール9をボール転走路7の終点から始点へ戻し循環させるボール循環路11と、を備えている。
このような第3実施形態の本例のボールねじ1の用途は特に限定されるものではないが、自動車部品,位置決め装置等に好適に使用可能である。
前述の粗成形工程及びボール循環路形成工程を塑性加工で行ったので、このボールねじ1の製造方法は、材料歩留まりが高いことに加えて、高精度のボールねじを安価に製造することができる。また、塑性加工により製造するため、鋼製素材20が有するメタルフロー(鍛流線)がほとんど切断されず、また、加工硬化するので、高強度のナット5が得られる。
第4実施形態は、ボールねじを構成するナットの製造方法、並びにその製造方法に用いられる金型及びその製造方法によって製造されるボールねじ用ナットに関する。
ボールねじは、内周面に螺旋溝が形成されたナットと、外周面に螺旋溝が形成されたねじ軸と、ナットの螺旋溝とねじ軸の螺旋溝で形成される軌道の間に配置されたボールと、前記ボールを軌道の終点から始点に戻すボール戻し経路とを備え、前記軌道内をボールが転動することで前記ナットがねじ軸に対して相対移動する装置である。
ボールねじのボール戻し経路には循環チューブ方式やコマ方式などがあり、コマ方式の場合は、ボール戻し経路をなす凹部が形成されたコマをナットの貫通穴に嵌めている。これに対して、下記の特許文献1には、ボール戻し経路をなす凹部(循環溝)を、ナット素材の内周面に塑性加工で直接形成することが記載されている。その形成方法について図26を用いて説明する。
(1)ボールとの接触により循環路内に鉄粉等の摩耗粉が発生する。
(2)循環路内で発生した摩耗粉がボールに付着して転走路に侵入する。
(3)転走路に侵入した摩耗粉がボールねじ溝とボールとの間で圧迫されることによってボールねじ溝やボールに圧痕が発生する。
(4)発生した圧痕に応力が集中して割れ等が生じ、最終的には表面剥離に至る。
(5)循環路内で発生した摩耗粉がグリース等の潤滑剤中に混入することで、ボールねじ溝表面に形成される潤滑油膜が部分的に破壊され、潤滑性能が低下して温度上昇や早期摩耗を引き起こすことが懸念される。
また、従来のコマ式ボールねじの場合、コマは焼結により形成されるため、同様に加工コストの問題があった。
そこで、第4実施形態は上記の問題点に着目してなされたものであり、その目的は、工程を増やさずに圧痕発生、表面剥離を防止することができるボールねじ用ナットの製造方法、並びにその製造方法に用いられる金型及びその製造方法によって製造されるボールねじ用ナットを提供することにある。
その結果、前記ナット素材の内周面に形成される凹部の表面粗さRa2 を、圧痕発生、表面剥離を防止することができる程度に小さくしたボールねじのナットの製造方法を提供することができる。
第4実施形態によれば、工程を増やさずに圧痕発生、表面剥離を防止することができるボールねじ用ナットの製造方法、並びにその製造方法に用いられる金型及びその製造方法によって製造されるボールねじ用ナットを提供することができる。
図22に示すように、第4実施形態の本例に使用する金型450は、ナット素材410を保持する凹部421を有する素材ホルダ420と、ナット素材410の内部に配置するカムスライダ430及びカムドライバ440とを備えている。
カムスライダ430は、図23(a)及び(b)に示すように、外周面431と軸方向に平行な平面432を有する略半円柱状部材であって、外周面431をなす円の径は、ナット素材410の内周面411をなす円411aの径より僅かに小さい。カムスライダ430の平面432には、径方向の中央部に、軸方向に延びる斜面433が形成されている。この斜面433は、軸方向一端(上端)の凹部434の底面ライン434aと、平面432の下端をなすライン432dを結ぶ平面に相当する。また、ボール戻し経路をなすS字状凹部415に対応するS字状凸部435が、カムスライダ430の外周面431に形成されている。
ここで、カムスライダ430は、少なくとも凸部435の表面435aが、例えば、バフ研磨などによって鏡面仕上げされている。この鏡面仕上げによって、表面435aの算術平均粗さRa1 は、0.01μm以上、0.2μm以下とされる。
カムドライバ440は、図23(c)に示すように、長尺な板状部材であって、一方の側面441がカムスライダ430の斜面433と同じ傾斜の斜面になっている。他方の側面442は、ナット素材410の内周面411をなす円411aに沿った円周面となっている。カムドライバ440の軸方向寸法は、カムスライダ430の軸方向寸法より長い。また、カムドライバ440の厚さは、カムスライダ430の凹部434の開口幅(斜面433の両側面間の寸法)に相当する厚さより僅かに薄い。
カムスライダ430の斜面431とカムドライバ440の傾斜した側面441が、金型450のカム機構を構成する。
第4実施形態に係るボールねじ用ナットの製造方法は、ナット素材410の内周面411に循環溝を形成する循環溝形成工程と、形成された循環溝の位置に基づいて内周面411に転動溝を形成する転動溝形成工程とを含む。
ここで、ナット素材410の材料としては、以下に説明する転動溝形成工程及び循環溝形成工程後の熱処理が浸炭処理の場合はSCM420が好ましく、高周波焼入れの場合はS53C、又はSAE4150であることが好ましい。
金型450を用い、以下の方法で、ナット素材410の内周面411にボール戻し経路(循環溝)をなすS字状凹部415を形成する。
まず、素材ホルダ420の凹部421にナット素材410を配置し、ナット素材410の内部に、カムスライダ430を、凹部434側を上にし、S字状凸部435をナット素材410の内周面411に向けて挿入する。次に、カムスライダ430とナット素材410の間にカムドライバ440を挿入する。その際に、カムスライダ430の凹部434にカムドライバ440の側面441側の部分を嵌めて、カムスライダ430の斜面433とカムドライバ440の傾斜した側面441を接触させる。図22(a)はこの状態を示す。
よって、第4実施形態の本例の方法によれば、軸方向寸法が長く内径が小さいナットを製造する場合でも、カムドライバ440に破損を生じさせずにS字状凹部415を形成することができる。
なお、ナット素材410の内周面411に二つのS字状凹部を形成する場合は、上述の方法で一つのS字状凹部415を形成した後、カムドライバ440を抜いてから、カムスライダ430を動かして凸部435の位置を変え、再度カムドライバ440を挿入して上述の方法を行う。三つ以上のS字状凹部415を形成する場合はこれを繰り返す。
次に、循環溝415が形成されたナット素材410の内周面411に、転動溝416を形成する。図24は、第4実施形態に係るボールねじ用ナットの製造方法の一例を説明する図であり、(a)は、ナット素材の切削加工の状態を示す斜視図であり、(b)は、(a)に示すナット素材と切削工具を矢印VA方向に見た図である。また、図25は、第4実施形態に係るボールねじ用ナットの製造方法の一例を説明する図であり、(a)は、ナット素材の切削加工後における軸線方向断面図であり、(b)は、ナット素材の切削加工後における斜視図である。
カムスライダ430に形成されたS字状凸部435の表面435aの算術平均粗さRa1 が0.01μm以上、0.2μm以下であるので、このカムスライダ430を有する金型450を用いて形成された循環溝416の算術平均粗さRa2 は、0μm超、1.6μm以下とされる。なお、この循環溝416の算術平均粗さRa2 は、少なくとも循環溝416においてボール(転動体)と接触する領域の粗さである。
また、加工ヘッド530の凸部537,538の表面の算術平均粗さRa1 を0.01~0.2μmとすれば、図26に示す方法を用いても、上記と同様の粗さを有する循環溝416を形成することができる。なお、循環溝416以外の部分の加工方法については、特に限定されるものではなく、適宜変更が可能である。
第5実施形態は、ボールねじ及びその製造方法に関する。
ボールねじは、螺旋状のねじ溝を外周面に有するねじ軸と、ねじ軸のねじ溝に対向するねじ溝を内周面に有するナットと、両ねじ溝により形成される螺旋状のボール転走路内に転動自在に装填された複数のボールと、からなる。そして、ボールを介してねじ軸に螺合されているナットとねじ軸とを相対回転運動させると、ボールの転動を介してねじ軸とナットとが軸方向に相対移動するようになっている。
これに対して、特許文献10に開示のボールねじは、チューブやコマは用いられることなく、ナットの内周面にボール循環路が塑性加工により直接形成されているので、高周波焼入れをナットの周方向に一様に施すことが可能となっている。
前記課題を解決するため、第5実施形態は次のような構成からなる。すなわち、第5実施形のボールねじは、螺旋状のねじ溝を外周面に有するねじ軸と、前記ねじ軸のねじ溝に対向するねじ溝を内周面に有するナットと、前記両ねじ溝により形成される螺旋状のボール転走路に転動自在に装填された複数のボールと、前記ボールを前記ボール転走路の終点から始点へ戻し循環させるボール循環路と、を備えるボールねじにおいて、前記ボール循環路は、前記ナットの内周面の一部を凹化させてなる凹溝で構成されているとともに、前記ナットのねじ溝の表面硬さがHRC58以上62以下、前記ボール循環路のうち前記ボール転走路との接続部分である両端部の表面硬さがHRC58以上62以下、前記ボール循環路のうち前記両端部の間の中間部の表面硬さがHV550以下であることを特徴とする。
また、第5実施形態のボールねじの製造方法は、上記のようなボールねじを製造するに際して、前記ボール循環路を構成する凹溝を鍛造により形成し、前記ナットのねじ溝を切削加工により形成した後に、前記ボール循環路のうち前記両端部のみと前記ナットのねじ溝とに高周波焼入れを施すことを特徴とする。
また、第5実施形態のボールねじの製造方法は、ナットの薄肉部分が硬化されないように高周波焼入れを施すので、ナットの耐久性が優れていることに加えて、ナットが小型であるボールねじを製造することができる。
図9に示すように、ボールねじ1は、螺旋状のねじ溝3aを外周面に有するねじ軸3と、ねじ軸3のねじ溝3aに対向する螺旋状のねじ溝5aを内周面に有するナット5と、両ねじ溝3a,5aにより形成される螺旋状のボール転走路7内に転動自在に装填された複数のボール9と、ボール9をボール転走路7の終点から始点へ戻し循環させるボール循環路11と、を備えている。
次に、第5実施形態のボールねじ1の製造方法の一例を、図16,17を参照しながら説明する。まず、円柱状の鋼製素材20を冷間鍛造等の塑性加工により加工し、ナット5と略同一形状(略円筒形状)のブランク21を得た(粗成形工程)。このとき、塑性加工により、ブランク21の外周面にはフランジ13も形成される。
ここで、高周波焼入れの内容について、ナット5を軸方向に沿う平面で切断した断面図である図27を参照しながら詳細に説明する。第5実施形態の本例においては、ナット5の内周面のうち一部分のみに高周波焼入れを施して、表面に焼入れ層を形成し、他の部分については高周波焼入れを施さず硬化させない。すなわち、ねじ溝5aに対しては高周波焼入れを施して、表面硬さをHRC58以上62以下とする。また、ボール循環路11(凹溝22)のうちボール転走路7との接続部分である両端部に対しては高周波焼入れを施して、その表面硬さをHRC58以上62以下とする。一方、ボール循環路11(凹溝22)のうち前記両端部の間の中間部に対しては高周波焼入れを施さず、その表面硬さをHV550以下とする。
ねじ溝5aは、ボール9を介して負荷を受ける負荷圏であるが、高周波焼入れにより表面に焼入れ層が形成されているため、大きな負荷に耐えることができる。また、ボール循環路11の両端部は、ボール転走路7との接続部分であり、ボール転走路7から導入されてきたボール9が突き当たり衝撃を受ける部分であるが、高周波焼入れにより表面に焼入れ層が形成されているため、前記衝撃に耐えることができる。また、摩耗も生じにくい。そのため、ボール循環路11の耐久性が優れている。
このようにして製造されたナット5と、慣用の方法により製造されたねじ軸3及びボール9とを組み合わせて、ボールねじ1を製造した。
前述の粗成形工程及びボール循環路形成工程を塑性加工で行ったので、このボールねじ1の製造方法は、材料歩留まりが高いことに加えて、高精度のボールねじを安価に製造することができる。また、塑性加工により製造するため、鋼製素材20が有するメタルフロー(鍛流線)がほとんど切断されず、また、加工硬化するので、高強度のナット5が得られる。
第6実施形態は、ボールねじに関する。
ボールねじは、螺旋状のねじ溝を外周面に有するねじ軸と、ねじ軸のねじ溝に対向するねじ溝を内周面に有するナットと、両ねじ溝により形成される螺旋状のボール転走路内に転動自在に装填された複数のボールと、からなる。そして、ボールを介してねじ軸に螺合されているナットとねじ軸とを相対回転運動させると、ボールの転動を介してねじ軸とナットとが軸方向に相対移動するようになっている。
前記課題を解決するため、第6実施形態は次のような構成からなる。すなわち、第6実施形態の一態様に係るボールねじは、螺旋状のねじ溝を外周面に有するねじ軸と、前記ねじ軸のねじ溝に対向するねじ溝を内周面に有するナットと、前記両ねじ溝により形成される螺旋状のボール転走路に転動自在に装填された複数のボールと、前記ボールを前記ボール転走路の終点から始点へ戻し循環させるボール循環路と、を備えるボールねじにおいて、下記の3つの条件A,B,Cを満足することを特徴とする。
条件B:前記ボール循環路は、前記ボール転走路との接続部分である両端部と、前記両端部の間に配された中間部と、前記端部と前記中間部とを接続する湾曲部と、からなり、略S字状をなしている。
条件C:前記凹溝の縁部のうち前記湾曲部の縁部は湾曲しており、その湾曲の径方向外方側の縁部は、曲率半径の異なる複数の円弧が滑らかに連続した形状に形成されている。
また、第6実施形態の別の態様に係るボールねじは、螺旋状のねじ溝を外周面に有するねじ軸と、前記ねじ軸のねじ溝に対向するねじ溝を内周面に有するナットと、前記両ねじ溝により形成される螺旋状のボール転走路に転動自在に装填された複数のボールと、前記ボールを前記ボール転走路の終点から始点へ戻し循環させるボール循環路と、を備えるボールねじにおいて、下記の3つの条件D,E,Fを満足することを特徴とする。
条件E:前記ボール循環路は、前記ボール転走路との接続部分である両端部と、前記両端部の間に配され互いに逆方向に湾曲する2つの湾曲部と、からなり、略S字状をなしている。
条件F:前記凹溝の縁部のうち前記両湾曲部の縁部は湾曲しており、その湾曲の径方向外方側の縁部は、曲率半径の異なる複数の円弧が滑らかに連続した形状に形成されている。
条件H:前記ボール循環路は、前記ボール転走路との接続部分である両端部と、前記両端部の間に配され互いに逆方向に湾曲する2つの湾曲部と、からなり、略S字状をなしている。
条件I:前記凹溝の縁部のうち前記両湾曲部の縁部は湾曲しており、その湾曲の径方向外方側及び径方向内方側の縁部は、単一の円弧形状に形成されている。
第6実施形態のボールねじは、ボール循環路の周方向長さが短く、その分だけボール転走路の長さが長くなっているので、負荷容量が大きく長寿命である。
[第1例]
図9は、第6実施形態の第1例のボールねじの構造を説明する断面図(軸方向に沿う平面で切断した断面図)である。
図9に示すように、ボールねじ1は、螺旋状のねじ溝3aを外周面に有するねじ軸3と、ねじ軸3のねじ溝3aに対向する螺旋状のねじ溝5aを内周面に有するナット5と、両ねじ溝3a,5aにより形成される螺旋状のボール転走路7内に転動自在に装填された複数のボール9と、ボール9をボール転走路7の終点から始点へ戻し循環させるボール循環路11と、を備えている。
なお、ねじ溝3a,5aの断面形状(長手方向に直交する平面で切断した断面の形状)は、円弧状(単一円弧状)でもよいしゴシックアーク状でもよい。また、ねじ軸3,ナット5,及びボール9の材質は特に限定されるものではなく、一般的な材料を使用可能である。例えば、金属(鋼等),焼結合金,セラミック,樹脂があげられる。
ここで、従来のボールねじのボール循環路について、図32を参照しながら説明する。なお、図29,30,31には、従来のボールねじのボール循環路の外周をなす縁部が2点鎖線で示されている。また、図32の符号304は、ボール転走路を示す。
なお、図29のボール循環路11においては、径方向外方側の縁部を構成する円弧の数は2つであったが、2つに限定されるものではなく、3つ以上でも差し支えない。また、図29のボール循環路11においては、湾曲部11cの径方向内方側の縁部を構成する円弧の曲率中心と、径方向外方側の縁部を構成する2つの円弧の曲率中心とが異なっているが、同一の曲率中心としてもよい。
次に、ブランク21の円柱面状の内周面の一部を冷間鍛造等の塑性加工(又は切削加工でもよい)により凹化させて、ボール転走路7の終点と始点を連通するボール循環路11をなす略S字状の凹溝22を形成した(ボール循環路形成工程)。
なお、前述の粗成形工程及びボール循環路形成工程を塑性加工で行ったので、このボールねじ1の製造方法は、材料歩留まりが高いことに加えて、高精度のボールねじを安価に製造することができる。また、塑性加工により製造するため、鋼製素材20が有するメタルフロー(鍛流線)がほとんど切断されず、また、加工硬化するので、高強度のナット5が得られる。
図30は、第6実施形態の第2例のボールねじの構造を説明する図であり、ナットの内周面の凹溝を示す図である。なお、第2例のボールねじの構成及び作用効果は、第1例とほぼ同様であるので、異なる部分のみ説明し、同様の部分の説明は省略する。また、これ以降の各図においては、図29と同一又は相当する部分には、図29と同一の符号を付してある。
このような構成により、ボール循環路11(凹溝22)の周方向長さLは、第1例の場合よりも短くなる。また、ボール循環路11内を進行するボール9の進行方向の変化も、第1例の場合よりも緩やかになる。
図31は、第6実施形態の第3例のボールねじの構造を説明する図であり、ナットの内周面の凹溝を示す図である。なお、第3例のボールねじの構成及び作用効果は、第1例,第2例とほぼ同様であるので、異なる部分のみ説明し、同様の部分の説明は省略する。
第3例のボールねじ1においては、ボール循環路11(凹溝22)は、ボール転走路7(ねじ溝5a)との接続部分である両端部11a,11aが直線状となっており、この直線状の端部11aによりボール9の導入部が形成されている。そして、該両端部11a,11aは、互いに逆方向に湾曲する2つの湾曲部11c,11cにより滑らかに接続されていて、ボール循環路11(凹溝22)の全体形状は略S字状をなしている。すなわち、第1例と比べると、直線状の中間部を備えていない点が異なっている。
このような構成により、ボール循環路11(凹溝22)の周方向長さLは、第1例の場合よりも短くなる。また、ボール循環路11内を進行するボール9の進行方向の変化も、第1例の場合よりも緩やかになる。
第7実施形態は、ボールねじに関する。
ボールねじは、螺旋状のねじ溝を外周面に有するねじ軸と、ねじ軸のねじ溝に対向するねじ溝を内周面に有するナットと、両ねじ溝により形成される螺旋状のボール転走路内に転動自在に装填された複数のボールと、からなる。そして、ボールを介してねじ軸に螺合されているナットとねじ軸とを相対回転運動させると、ボールの転動を介してねじ軸とナットとが軸方向に相対移動するようになっている。
そこで、第7実施形態は、上記のような従来技術が有する問題点を解決し、負荷容量及び寿命の低下並びに製造コストの上昇を伴うことなく潤滑性を向上させたボールねじを提供することを課題とする。
また、前記ボール循環路は湾曲しており、前記ボール循環路の湾曲の径方向外方側に配された潤滑剤溜まりよりも、前記ボール循環路の湾曲の径方向内方側に配された潤滑剤溜まりの方が、前記ボール循環路の長手方向に直交する平面で切断した断面の面積が大きいことが好ましい。
第7実施形態のボールねじは、ナットのボール循環路に潤滑剤溜まりを備えることにより、負荷容量及び寿命の低下並びに製造コストの上昇を伴うことなく、優れた潤滑性を実現している。
[第1例]
図9は、第7実施形態の第1例のボールねじの構造を説明する断面図(軸方向に沿う平面で切断した断面図)である。
図9に示すように、ボールねじ1は、螺旋状のねじ溝3aを外周面に有するねじ軸3と、ねじ軸3のねじ溝3aに対向する螺旋状のねじ溝5aを内周面に有するナット5と、両ねじ溝3a,5aにより形成される螺旋状のボール転走路7内に転動自在に装填された複数のボール9と、ボール9をボール転走路7の終点から始点へ戻し循環させるボール循環路11と、を備えている。
なお、ねじ溝3a,5aの断面形状は、円弧状(単一円弧状)でもよいしゴシックアーク状でもよい。また、ねじ軸3,ナット5,及びボール9の材質は特に限定されるものではなく、一般的な材料を使用可能である。例えば、金属(鋼等),焼結合金,セラミック,樹脂があげられる。
さらに、凹部31の深さ(ナット5の径方向の長さ)は、凹部31の長手方向の中央において最も深くなっているが、いずれの部分においても、その深さは凹溝22の曲率半径(中間部24の溝幅tの1/2)よりも小さくなっている。
次に、ブランク21の円柱面状の内周面の一部を冷間鍛造等の塑性加工(又は切削加工でもよい)により凹化させて、ボール転走路7の終点と始点を連通するボール循環路11をなす略S字状の凹溝22を形成した(ボール循環路形成工程)。さらに、油溜まりを構成する凹部31を塑性加工(又は切削加工でもよい)により形成した。
なお、前述の粗成形工程及びボール循環路形成工程を塑性加工で行ったので、このボールねじ1の製造方法は、材料歩留まりが高いことに加えて、高精度のボールねじを安価に製造することができる。また、塑性加工により製造するため、鋼製素材20が有するメタルフロー(鍛流線)がほとんど切断されず、また、加工硬化するので、高強度のナット5が得られる。
図35~37は、第7実施形態の第2例のボールねじの構造を説明する図である。図35は、ナットの内周面の凹溝及び凹部を示す図であり、図36,37は、図35の凹溝及び凹部の断面図である。なお、第2例のボールねじの構成及び作用効果は、第1例とほぼ同様であるので、異なる部分のみ説明し、同様の部分の説明は省略する。また、これ以降の各図においては、図9~11及び図33,34と同一又は相当する部分には、図9~11及び図33,34と同一の符号を付してある。
さらに、ボール転走路7からボール循環路11に入ってきたボール9は、導入部25を通って中間部24の湾曲部分に突き当たることにより案内されて、進行方向を変える。導入部25にもボール9が突き当たるので、図37から分かるように、湾曲の径方向内方側(図37においては右側)よりも径方向外方側(図37においては左側)の方が、前記断面積が小さい凹部31が形成されている。よって、ボール循環路11の循環性(ボール9の案内性能)はほとんど低下しない。
図38は、第7実施形態の第3例のボールねじの構造を説明する図であり、ナットの内周面の凹溝及び凹部を示す図である。なお、第3例のボールねじの構成及び作用効果は、第1例,第2例とほぼ同様であるので、異なる部分のみ説明し、同様の部分の説明は省略する。
また、前記各実施形態におけるボール循環溝は、前述した図22,26に示す鍛造に限らず、他の塑性加工や、切削加工,放電加工等の除去加工により形成してもよい。
さらに、ナットの熱処理について詳細な条件等が記載されていない場合は、他の実施形態に記載された熱処理条件をはじめ、一般的な熱処理条件を問題なく適用することができる。
図39において、ステアリングギヤケースを構成するラック&ピニオンハウジング621内には、ラック&ピニオン機構を構成するラックシャフト623や図示しないピニオンが内装され、ピニオンはロアシャフト622に連結されている。ラックシャフト623は、ピニオンに噛合するラック625が図の左方に形成されていると共に、両端部には、タイロッド615を揺動自在に支持する球面継手627が固定されている。ボールねじのねじ軸は、このラックシャフト623に使用されている。
ラックシャフト623の図示右方には、雄ボールねじ溝(ねじ部)651が形成される。一方、ボールナット645には、雌ボールねじ溝653が形成され、雄ボールねじ溝651と雌ボールねじ溝653との間には、循環ボールを構成する多数個の鋼球655が介装されている。また、ボールナット645には、鋼球655を循環させるための図示しない循環溝が装着されている。
201a 螺旋溝
201b ねじ軸の外周面(ランド部)
202 ナット
202a 螺旋溝
202b 貫通穴
202d ナットの内周面(ボール循環溝の側面に連続する、軸方向に延びる面) 203 ボール
204 コマ
241 ボール循環溝
241a 溝底
241b 側面
241c 角部
242 ボール循環溝の側面に連続する軸方向に延びる面
205 金型
251 基部の面
252,253 ボール循環溝に対応させた突起
Claims (18)
- 螺旋状のねじ溝を外周面に有するねじ軸と、前記ねじ軸のねじ溝に対向するねじ溝を内周面に有するナットと、前記両ねじ溝により形成される螺旋状のボール転走路に転動自在に装填された複数のボールと、前記ボールを前記ボール転走路の終点から始点へ戻し循環させるボール循環溝と、を備え、前記ボール循環溝の両側面と前記各側面に連続し軸方向に延びる面とで形成される角部の少なくとも一部分が、丸く形成されていることを特徴とするボールねじ。
- 前記ナットは、前記ナットの内周面の一部を凹化させて、凹溝からなる前記ボール循環溝を形成した上、前記ナットの内周面に、前記ボール循環溝の端部と接続するように前記ねじ溝を形成することにより形成されたものであることを特徴とする請求項1に記載のボールねじ。
- 潤滑剤を保持可能な潤滑剤溜まりを備えており、該潤滑剤溜まりは、前記凹溝の内面の一部を凹化させてなる凹部からなることを特徴とする請求項2に記載のボールねじ。
- 前記ボール循環溝は、前記ボール転走路との接続部分である両端部と、前記両端部の間の中間部とからなり、前記ボール循環溝の長手方向に直交する平面で切断した前記潤滑剤溜まりの断面の面積は、前記端部に隣接する部分よりも前記中間部に隣接する部分の方が大きいことを特徴とする請求項3に記載のボールねじ。
- 前記ボール循環溝は湾曲しており、前記ボール循環溝の湾曲の径方向外方側に配された潤滑剤溜まりよりも、前記ボール循環溝の湾曲の径方向内方側に配された潤滑剤溜まりの方が、前記ボール循環溝の長手方向に直交する平面で切断した断面の面積が大きいことを特徴とする請求項3に記載のボールねじ。
- 前記ボール循環溝を構成する凹溝及び前記潤滑剤溜まりを構成する凹部は、同時に形成されたものであることを特徴とする請求項3に記載のボールねじ。
- 前記ボール循環溝の表面の算術平均粗さRa2 が0μm超1.6μm以下であることを特徴とする請求項2に記載のボールねじ。
- 円筒状のナット素材に内挿され、その軸方向に沿って移動するカムドライバと、
前記ナット素材とカムドライバとの間に配置され、前記ボール循環溝に対応する凸部が形成され、前記カムドライバの移動により前記凸部が前記ナットの径方向に移動するカムスライダと、を有し、
前記凸部の表面の算術平均粗さRa1 が0.01μm以上0.2μm以下である、カム機構の金型を用いたプレス法により、前記凸部で前記ナット素材の内周面を押すことで、前記ナット素材の内周面に前記ボール循環溝を形成したことを特徴とする請求項7に記載のボールねじ。 - 前記ボール循環溝は、前記ナットの内周面の一部を凹化させてなる凹溝で構成されているとともに、前記ナットのねじ溝の表面硬さがHRC58以上62以下、前記ボール循環溝のうち前記ボール転走路との接続部分である両端部の表面硬さがHRC58以上62以下、前記ボール循環溝のうち前記両端部の間の中間部の表面硬さがHV550以下であることを特徴とする請求項2に記載のボールねじ。
- 前記ボール循環溝のうち前記両端部のみと前記ナットのねじ溝とに高周波焼入れが施されていることを特徴とする請求項2に記載のボールねじ。
- 前記ナットは、前記ボール循環溝と前記ボール転走路との境界部分にブラシ加工及びブラスト加工の少なくとも一方を施してバリを除去することにより形成されたものであることを特徴とする請求項2に記載のボールねじ。
- 下記の3つの条件A,B,Cを満足することを特徴とする請求項2に記載のボールねじ。
条件A:前記ボール循環溝は、前記ナットの内周面の一部を凹化させて形成した凹溝で構成されている。
条件B:前記ボール循環溝は、前記ボール転走路との接続部分である両端部と、前記両端部の間に配された中間部と、前記端部と前記中間部とを接続する湾曲部と、からなり、略S字状をなしている。
条件C:前記凹溝の縁部のうち前記湾曲部の縁部は湾曲しており、その湾曲の径方向外方側の縁部は、曲率半径の異なる複数の円弧が滑らかに連続した形状に形成されている。 - 前記ボール循環溝は、前記ボール転走路との接続部分である両端部と、前記両端部の間に配された中間部と、を備えており、前記端部の溝幅よりも前記中間部の溝幅の方が狭いことを特徴とする請求項2に記載のボールねじ。
- 下記の3つの条件D,E,Fを満足することを特徴とする請求項2に記載のボールねじ。
条件D:前記ボール循環溝は、前記ナットの内周面の一部を凹化させて形成した凹溝で構成されている。
条件E:前記ボール循環溝は、前記ボール転走路との接続部分である両端部と、前記両端部の間に配され互いに逆方向に湾曲する2つの湾曲部と、からなり、略S字状をなしている。
条件F:前記凹溝の縁部のうち前記両湾曲部の縁部は湾曲しており、その湾曲の径方向外方側の縁部は、曲率半径の異なる複数の円弧が滑らかに連続した形状に形成されている。 - 下記の3つの条件G,H,Iを満足することを特徴とする請求項2に記載のボールねじ。
条件G:前記ボール循環溝は、前記ナットの内周面の一部を凹化させて形成した凹溝で構成されている。
条件H:前記ボール循環溝は、前記ボール転走路との接続部分である両端部と、前記両端部の間に配され互いに逆方向に湾曲する2つの湾曲部と、からなり、略S字状をなしている。
条件I:前記凹溝の縁部のうち前記両湾曲部の縁部は湾曲しており、その湾曲の径方向外方側及び径方向内方側の縁部は、単一の円弧形状に形成されている。 - 前記ボール循環溝は、前記ナットの内周面の一部を凹化させて形成した凹溝で構成されており、前記ボール循環溝の長手方向の少なくとも一部分は、前記長手方向に直交する平面で切断した場合の断面形状が略V字状をなしていることを特徴とする請求項2に記載のボールねじ。
- 前記ボール循環溝は、前記ボール転走路との接続部分である両端部と、前記両端部の間の中間部とからなり、前記中間部及び前記端部の少なくとも一方は、前記ボール循環溝の長手方向に直交する平面で切断した場合の断面形状が略V字状をなしていることを特徴とする請求項16に記載のボールねじ。
- 前記ボール循環溝を構成する凹溝の底部に潤滑剤溜まりを設けたことを特徴とする請求項16に記載のボールねじ。
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
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JP2012544076A JP5569592B2 (ja) | 2010-11-15 | 2011-03-31 | ボールねじ |
CN201180054525.8A CN103228953B (zh) | 2010-11-15 | 2011-03-31 | 滚珠丝杠 |
US13/879,752 US20130220047A1 (en) | 2010-11-15 | 2011-03-31 | Ball Screw |
EP11841142.0A EP2642161B1 (en) | 2010-11-15 | 2011-03-31 | Ball screw |
KR1020137010134A KR101562716B1 (ko) | 2010-11-15 | 2011-03-31 | 볼 나사 |
Applications Claiming Priority (14)
Application Number | Priority Date | Filing Date | Title |
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JP2010255390 | 2010-11-15 | ||
JP2010-255390 | 2010-11-15 | ||
JP2010-256268 | 2010-11-16 | ||
JP2010256268 | 2010-11-16 | ||
JP2010-262333 | 2010-11-25 | ||
JP2010262333 | 2010-11-25 | ||
JP2010-264141 | 2010-11-26 | ||
JP2010264141 | 2010-11-26 | ||
JP2010266374 | 2010-11-30 | ||
JP2010-266374 | 2010-11-30 | ||
JP2010-279354 | 2010-12-15 | ||
JP2010279354 | 2010-12-15 | ||
JP2011-001885 | 2011-01-07 | ||
JP2011001885 | 2011-01-07 |
Publications (1)
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WO2012066693A1 true WO2012066693A1 (ja) | 2012-05-24 |
Family
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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PCT/JP2011/001973 WO2012066693A1 (ja) | 2010-11-15 | 2011-03-31 | ボールねじ |
Country Status (6)
Country | Link |
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US (1) | US20130220047A1 (ja) |
EP (1) | EP2642161B1 (ja) |
JP (1) | JP5569592B2 (ja) |
KR (1) | KR101562716B1 (ja) |
CN (1) | CN103228953B (ja) |
WO (1) | WO2012066693A1 (ja) |
Cited By (2)
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US20160223059A1 (en) * | 2013-09-19 | 2016-08-04 | Nsk Ltd. | Ball Screw |
TWI711779B (zh) * | 2019-08-13 | 2020-12-01 | 上銀科技股份有限公司 | 滾珠螺桿 |
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KR101414381B1 (ko) * | 2010-03-17 | 2014-07-01 | 닛본 세이고 가부시끼가이샤 | 볼 나사, 및 볼 나사용 너트의 제조방법 |
WO2011122053A1 (ja) | 2010-03-31 | 2011-10-06 | 日本精工株式会社 | ボールねじ用ナットの製造方法及びボールねじ |
JP6187807B2 (ja) * | 2013-03-12 | 2017-08-30 | 株式会社ジェイテクト | ボールねじ装置 |
JP2015047997A (ja) * | 2013-09-03 | 2015-03-16 | 日立オートモティブシステムズステアリング株式会社 | パワーステアリング装置およびパワーステアリング装置の製造方法 |
JP6577195B2 (ja) * | 2015-02-04 | 2019-09-18 | Ntn株式会社 | 駒式ボールねじの製造方法 |
WO2016159303A1 (ja) * | 2015-04-02 | 2016-10-06 | 日本精工株式会社 | ねじ軸及びその製造方法、並びにボールねじ装置 |
JP6601792B2 (ja) * | 2015-09-24 | 2019-11-06 | Ntn株式会社 | ボールねじ |
WO2018088506A1 (ja) * | 2016-11-14 | 2018-05-17 | 日本精工株式会社 | ボールねじ |
JP6787139B2 (ja) * | 2017-01-11 | 2020-11-18 | 株式会社ジェイテクト | ボールねじ装置、及びボールねじ装置を備えるステアリング装置 |
DE112018006640T5 (de) * | 2017-12-29 | 2020-11-19 | ZF Active Safety U.S. Inc. | Kugelmutteranordnung |
JP6954220B2 (ja) * | 2018-04-24 | 2021-10-27 | 日本精工株式会社 | ボールねじ |
KR102230511B1 (ko) * | 2021-01-11 | 2021-03-23 | 주식회사 제이엠테크 | 휴대폰 액정표시장치 접합을 위한 지그 제조방법 |
KR102247211B1 (ko) * | 2021-03-04 | 2021-05-03 | 주식회사 제이엠테크 | 휴대폰 액정표시장치 접합을 위한 지그 제조방법 |
CN114439893A (zh) * | 2022-01-19 | 2022-05-06 | 慈兴集团有限公司 | 一种一体式回球丝杆结构 |
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TWI711779B (zh) * | 2019-08-13 | 2020-12-01 | 上銀科技股份有限公司 | 滾珠螺桿 |
Also Published As
Publication number | Publication date |
---|---|
CN103228953A (zh) | 2013-07-31 |
CN103228953B (zh) | 2016-04-27 |
KR20130091766A (ko) | 2013-08-19 |
EP2642161B1 (en) | 2020-06-24 |
JPWO2012066693A1 (ja) | 2014-05-12 |
JP5569592B2 (ja) | 2014-08-13 |
US20130220047A1 (en) | 2013-08-29 |
EP2642161A4 (en) | 2017-12-06 |
EP2642161A1 (en) | 2013-09-25 |
KR101562716B1 (ko) | 2015-10-22 |
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