CN107269788B

CN107269788B - Ball screw

Info

Publication number: CN107269788B
Application number: CN201710201154.0A
Authority: CN
Inventors: 坂井哲也; 武石正和
Original assignee: Co Ltd No 1; Nippon Thompson Co Ltd
Current assignee: Co Ltd No 1; Nippon Thompson Co Ltd
Priority date: 2016-03-30
Filing date: 2017-03-30
Publication date: 2021-07-13
Anticipated expiration: 2037-03-30
Also published as: TW201734332A; CN107269788A; JP6777415B2; KR102324533B1; JP2017180664A; TWI708017B; KR20170113363A

Abstract

The ball screw can be applied to various devices such as mechatronics products and detection devices, and the lubricating agent is continuously supplied from the oil-containing part (5) to the oil supply part (6), so that the balls (9) rolling in the direction switching path (14) contact the oil supply part (6) to supply the lubricating agent, and the effect of lubrication-free maintenance is achieved. The ball screw comprises a screw shaft (1) having a spiral groove (11) and a nut (2) that moves relative to the screw shaft. Nut (2) comprising: a nut body (3) formed with a second spiral groove (12) and a return path (13); an end cap (4) attached to the nut body (3) and having a direction change path (14) that communicates the spiral track (15) and the return path (13); an oil-containing member (5) disposed on the end cover (4); and an oil supply member (6) disposed in the communication hole (20) of the end cover (4).

Description

Ball screw

Technical Field

The present invention relates to a ball screw which can be incorporated into and used in various devices such as an mechatronic product such as a precision positioning table and a detection device, and which has a grease supply unit including a screw shaft and a nut that moves relative to the screw shaft.

Background

Conventionally, as a linear motion device that stably supplies lubricant by a self-lubricating method, for example, a device disclosed in japanese patent application laid-open No. 2013-174255 has been known. The linear motion device is a ball screw driving device of an end cover deflection type circulation mode, and comprises: a nut having a spiral groove formed on an inner circumferential surface thereof; a screw shaft having a spiral groove formed on an outer circumferential surface thereof to face the spiral groove of the nut; and a plurality of balls that are inserted between spiral raceway surfaces formed by the spiral groove of the nut and the spiral groove of the screw shaft. In the interior of the nut, a return passage is formed on the surface thereof by integral injection molding with an oil-containing resin in the axial direction.

Further, the present applicant has developed a rolling guide unit in which the degree of freedom of design is enhanced, the management of the lubricating oil is simple, and the sliding resistance against the rolling elements is small, and has already filed a patent (for example, refer to japanese patent application laid-open No. 2006-38195). The rolling guide assembly includes: a cylinder member through which the crossbar is slidably inserted; a track path formed by the barrel member and the crossbar in combination; a circulation path which communicates both ends of a track path formed in the cylindrical member through the concave portion of the direction change path; and a plurality of rolling bodies that roll in the circulation path and the raceway path. The rolling guide assembly circulates the rolling bodies in a circulating path and an orbital path in accordance with the relative movement of the cross bar and the barrel member. The rolling guide assembly includes: the oil supply member is provided along a contact surface of the rolling element in the raceway path or the circulation path, and is brought into contact with the oil-containing member.

However, the linear motion device is formed integrally with the nut by injection molding the oleoresin material in the return passage of the nut. Since the oil-containing resin material is formed by mixing the resin material and the lubricating oil in advance and then injection molding the mixed material, the lubricating oil cannot be supplied when the capacity of the lubricating oil is small, and lubrication failure is likely to occur, and the oil-containing resin material needs to be injection molded integrally with the nut, which causes problems of high labor and high manufacturing cost. In addition, the rolling guide unit has an effect of being free from lubrication maintenance by providing an oil supply member in the direction change path of the end cap of the ball spline and an oil-containing member in the outer cylinder, but since the oil-containing member is fitted in the fitting hole, there is a problem that the supply of the lubricating oil from the oil-containing member to the oil supply member is insufficient.

Disclosure of Invention

The present invention has been made to solve the above problems, and an object of the present invention is to provide a ball screw which can be incorporated into and used in various devices such as an mechatronic product such as a precision positioning table and a detection device, a recessed part is formed on the outer end surface of an end cover constituting an internal return plate, an oil-containing member impregnated with a lubricant and capable of supplying the lubricant is disposed in the recessed part, the device itself is small and simple, an oil supply member is disposed so as to be fitted into a communication hole opened in a direction change path of an end cover, the oil supply member and the oil supply member are formed of a porous sintered resin impregnated with a lubricant, and the oil-containing member constantly supplies the lubricant to the oil supplying member to bring the balls rolling in the direction change path as rolling bodies into contact with the exposed surface of the oil supplying member, thereby, the lubricant is reliably and properly supplied to the balls, and the effect of lubrication-free maintenance can be achieved.

The present invention relates to a ball screw, which comprises: a rotatable screw shaft having a first spiral groove formed in a spiral shape in an axial direction on an outer peripheral surface thereof, the first spiral groove being formed to allow a plurality of balls as rolling elements to roll; and a cylindrical nut fitted to the outer peripheral surface of the screw shaft and having a second spiral groove formed on an inner peripheral surface thereof in a spiral shape in an axial direction, the second spiral groove facing the first spiral groove and allowing the balls to roll. It is constituted as follows: the nut moves relatively on the screw shaft along the length direction along with the rotation of the screw shaft;

the nut includes: a cylindrical nut body in which the second spiral groove and a return path extending in the axial direction along which the balls roll are formed; end caps which are respectively arranged at both ends of the nut main body and which are formed with direction changing paths that communicate the spiral track formed by the first spiral groove and the second spiral groove with the return path; an oil-containing member disposed on an outer end surface of the end cap and impregnated with a lubricant; and an oil supply member disposed in a communication hole formed in the end cap and communicating the direction change path with the outer end surface of the end cap on the oil-containing member side;

an elastic protrusion pressed against the oil-containing member is integrally provided on one end surface of the oil supply member on the oil-containing member side;

the ball rolling in the direction change path contacts the other end surface of the oil supply member to supply the lubricant to the ball, and the convex portion of the oil supply member is pressed against the oil-containing member to replenish the lubricant to the oil supply member.

The nut is provided with a cover for covering an outer surface of the oil-containing member, and the cover is fixed to the nut body with the end cover and the oil-containing member interposed therebetween. The nut body has a flange portion formed with an attachment hole for attaching an engaging member.

Further, the oil-containing member is accommodated in the cap disposed on the outer end surface of the end cap, and is formed in a C-shaped ring shape so as to align with a sealing projection provided on the cap. The ball rolls in a circulation path including the spiral track, the return path, and the direction change path as the screw shaft rotates, and the nut is relatively moved in the longitudinal direction on the screw shaft by the ball.

The screw shaft is configured as a round-shaft type ball screw shaft having both ends rotatably supported. Further, the communication hole formed in the end cover is opened in an outer wall surface of the direction change path that is bent in an R-shape, and the other end surface of the oil supply member exposed in the direction change path is formed in the same shape of the outer wall surface that is bent in an R-shape.

Further, the width of the other end surface of the oil supply member exposed in the direction change path is set within a range of 1/4 to 1/2 of the diameter of the ball. Further, the end cap is an internal return plate formed with a convex portion of the direction change path communicating the spiral track and the return path and a click claw for catching the ball on the spiral track side, and the convex portion of the internal return plate is fitted into a concave portion formed at each end portion of the nut main body and communicating with each end portion of the second spiral groove.

The oil-containing member and the oil-supplying member are each formed of a porous molded body formed by compacting and then thermoforming fine synthetic resin particles of polyethylene or polypropylene and having porous portions in which the fine synthetic resin particles are kept in communication with each other, and the porous portions are impregnated with the lubricant.

The ball screw according to the present invention is configured as described above, and the ball screw itself is configured to be simple and small in size, and a large amount of lubricant can be impregnated into the oil-containing member disposed in the concave portion of the cap provided on the outer end surface of the end cap, and the convex portion of the oil supply member disposed in the communication hole of the end cap is pressed against the oil-containing member, whereby the lubricant can be reliably and smoothly moved from the oil-containing member to the oil supply portion due to a capillary phenomenon or the like. The lubricant immersed in the oil-containing member is smoothly supplied to the oil supply member, and the balls rolling in the direction change path come into contact with the exposed end surface of the oil supply member, whereby the lubricant easily seeps out of the oil supply member and is supplied to the balls, and lubrication-free maintenance of the ball screw can be achieved. In addition, the ball screw has a C-shaped ring shape in which the oil-containing member disposed in the recess of the cover is formed. Further, a sealing projection is provided on the inner peripheral side of the cover so as to be fitted to the spiral groove of the screw shaft, and entry of foreign matter can be prevented by the sealing projection. Further, since the outer side of the oil-impregnated member is covered with the cover, the surrounding environment is not contaminated by scattering of the lubricant.

Drawings

Fig. 1 is a perspective view showing one embodiment of a ball screw of the present invention.

Fig. 2 is an exploded perspective view illustrating a nut constituting the ball screw of fig. 1.

Fig. 3 is a side view of a part of the circulation path in which balls roll, the part being cut away from the ball screw of fig. 1.

Fig. 4 is a front view showing an outer end face of an end cap constituting the ball screw of fig. 3.

Fig. 5 is a sectional view showing an a-a position of an end cap constituting the ball screw of fig. 4.

FIG. 6 is a rear view showing the inboard end face of the end cap of FIG. 4.

Fig. 7A is a side view showing an oil supply member constituting the ball screw of fig. 1.

Fig. 7B is a plan view showing an oil supply member constituting the ball screw of fig. 1.

Fig. 8A is a front view showing an oil-containing member constituting the ball screw of fig. 1.

Fig. 8B is a side view showing an oil-containing member constituting the ball screw of fig. 1.

Fig. 9A is a front view showing an outer end face of a cap constituting the ball screw of fig. 1.

Fig. 9B is a sectional view showing a B-B position in fig. 9A.

Fig. 9C is a rear view showing an inner side end surface of a cover constituting the ball screw of fig. 1.

Fig. 9D is a side view showing a cover constituting the ball screw of fig. 1.

Description of reference numerals

1: screw shaft

2: nut

3: nut body

4: end cap

5: oil-containing member

6: oil supply component

7: cover

8: flange part (nut main body)

9: rolling ball (Rolling element)

10: outer peripheral surface (screw shaft)

11: spiral groove (first spiral groove, screw shaft)

12: spiral groove (second spiral groove, nut main body)

13: return path (nut body)

14: direction change path (end cap)

15: spiral track

16: circulation path

17: inner peripheral surface (nut main body)

18: end (nut main body)

19: end face (end cap)

20: intercommunicating pore (end cap)

21: end face (oil supply component, direction switching path side)

22: end face (oil supply part, oil-containing part side)

23: convex part (projection of oil supply component)

24: outer surface (oil-containing component)

25: mounting hole (flange)

26: end (screw shaft)

27: outer wall (Direction changing path)

28: concave part (end of nut main body)

29: jack catch (end cap)

30: convex part (end cap)

31: fixing screw (fixing nut main body, end cap, cover)

32: cut-out portion (oil-containing component)

33: inserting hole (nut body)

34: inserting hole (end cap)

35: inserting hole (oil-containing component)

36: concave part (oil-containing component)

37: inserting hole (cover)

38: end face (cover, outer side)

39: outer peripheral surface (cover)

40: concave part (cover)

41: counterboring hole (cover)

42: end face (end cap, convex side)

43: mounting hole (end cap)

44: opening (Direction Change path)

45: end face (oil-containing component, inner side)

46: screw hole for mounting (nut main body)

47: end face (nut main body)

50: convex part (cover)

Detailed Description

The ball screw according to the present invention is preferably applied to various apparatuses such as an mechatronic product such as a precision positioning table and a detection device.

Hereinafter, an embodiment of a ball screw according to the present invention will be described with reference to the drawings. As shown in fig. 1 to 3, the ball screw of the present invention includes: a screw shaft 1 which is a rotatable ball screw shaft having an outer circumferential surface 10 in which a spiral groove 11 (first spiral groove) in which a plurality of balls 9 as rolling elements roll is formed in an axial direction; and a cylindrical nut 2 fitted to the outer peripheral surface 10 of the threaded shaft 1 and having a spiral groove 12 (second spiral groove) formed on the inner peripheral surface 17 thereof in the axial direction so as to face the spiral groove 11 and in which the balls 9 roll; as the screw shaft 1 rotates, the nut 2 moves relative to the screw shaft 1 in the longitudinal direction.

In particular, the nut 2 is characterized in that it comprises: a cylindrical nut body 3 having a spiral groove 12 and a return path 13 extending in a longitudinal direction in which the balls 9 roll; end caps 4 which are disposed on both end surfaces 47 of the nut body 3, and which are formed with direction changing paths 14 that communicate the spiral tracks 15 formed by the

spiral grooves

11 and 12 with the return paths 13; an oil-impregnated member 5 disposed on the outer end surface 19 of the end cap 4 and impregnated with a lubricant; and an oil supply member 6 disposed in a communication hole 20 formed in the end cover 4 and communicating the direction change path 14 with an outer end surface 19 of the end cover 4 on the oil-containing member 5 side. The ball screw is provided with a cap 7 for covering an outer surface 24 of the oil-impregnated member 5 on the nut 2. The cover 7 is fixed to the nut body 3 via the end cover 4 and the oil-containing member 5 by a fixing screw 31. A plurality of mounting screw holes 46 are formed in an end surface 47 of the nut body 3. And a fixing screw 31 inserted through the counter-boring mounting hole 41 of the cap 7, the recess 36 of the oil-impregnated member 5, and the mounting hole 43 of the end cap 4 and screwed into the mounting screw hole 46 of the nut body 3 to fix the end cap 4, the oil-impregnated member 5, and the cap 7 to the nut body 3.

The ball screw is formed in the following manner: in order to insert the screw shaft 1 into the nut 2 and to enable the screw shaft 1 to be inserted into the nut 2, an insertion hole 33, an insertion hole 34, an insertion hole 35, and an insertion hole 37 are formed in a nut body 3, an end cap 4, an oil-containing member 5, and a cover 7, which constitute the nut 2, so as to be aligned with each other. The oil-containing member 5 is accommodated in the cap 7 disposed on the outer end surface 19 of the end cap 4, and a part of the C-shaped ring shape is formed as a notch 32 so as to align with the sealing protrusion 50 provided on the cap 7. The sealing projection 50 is provided to be in contact with the spiral groove 11 of the screw shaft 1, and the sealing projection 50 reduces the gap between the screw shaft 1 and the nut 2, and functions as a labyrinth seal to prevent entry of foreign matter. When the lid 7 and the oil-containing member 5 are assembled, the sealing protrusion 50 of the lid 7 and the cutout 32 of the oil-containing member 5 may be fitted to each other. A recess 36 through which the fixing screw 31 penetrates is formed in the outer peripheral surface of the oil-impregnated member 5. The cover 7 is formed by an insertion hole 37 through which the screw shaft 1 passes at the center, an end surface 38 covering the oil-containing member 5 on the outside, and a ring-shaped outer peripheral surface 39 around the end surface, and a recess 40 accommodating the oil-containing member 5 is formed inside the outer peripheral surface 39. The cover 7 is provided with a plurality of spot facing attachment holes 41 (four in fig. 9) for inserting the fixing screws 31 therethrough. The oil-impregnated member 5 is accommodated in the recess 40 of the cover 7, and is inserted in a state where the outer side is covered.

The screw shaft 1 is configured as a round-shaft type ball screw shaft in which both end portions 26 are rotatably supported. In addition, the flange portion 8 having the mounting hole 25 formed therein is provided at the one end portion 18 of the nut body 3 for mounting an engaging member such as a workpiece, a tool, or equipment. In the end cap 4, a claw 29 for catching the ball 9 rolling from the spiral groove 11 on the screw shaft 1 side, a direction change path 14 for changing the direction of the ball 9, and an inlet/outlet port portion for guiding the ball 9 from the direction change path 14 to the return path 13 are formed in the convex portion 30 constituting one type of the internal return plate. The convex portions 30 of the end cap 4 are fitted into the concave portions 28 as fitting holes formed in the both end portions 18 of the nut body 3, and the direction change path 14 formed in the end cap 4 communicates with the spiral groove 12 formed in the nut body 3.

In this ball screw, the circulation path 16 of the balls 9 includes: the spiral track 15 of the ball 9, which is formed by opposing the spiral groove 11 of the screw shaft 1 and the spiral groove 12 of the nut body 3, the return path 13 formed in the nut body 3, and the direction change path 14 formed in each of the pair of end caps 4. In this ball screw, in general, the balls 9 roll in the circulation path 16 in accordance with the rotation of the screw shaft 1, and the nut 2 is relatively moved in the longitudinal direction on the screw shaft 1 by the balls 9.

The ball screw is supplied with lubricant from the oil-containing member 5 disposed outside the end cover 4 to the balls 9 rolling in the direction change path 14 via the oil supply member 6. The oil-impregnated member 5 is disposed on the outer end surface 19 (fig. 2) of the end cover 4 on the side opposite to the end surface 42 on which the convex portion 30 is formed. The communication hole 20 formed in the end cap 4 has one end opened in the form of a rectangular opening 44 of the R-shaped outer wall surface 27 of the direction change path 14, and the other end opened in the outer end surface 19 of the end cap 4. The communication hole 20 formed in the end cover 4 is fitted with the oil supply member 6, and the end surface 21 of the oil supply member 6 exposed in the direction change path 14 is formed in a shape bent in the same R shape corresponding to the outer wall surface 27 of the direction change path 14. In particular, in order to enable reliable supply of the lubricant, an elastically deformable, i.e., elastic protrusion 23 pressed against the inner end surface 45 of the oil-containing member 5 is integrally provided on the end surface 22 of the oil supply member 6 on the oil-containing member 5 side. In this ball screw, since the projection 23 on the one end side of the oil supply member 6 is disposed in contact with the end surface 45 on the end cap 4 side of the oil-containing member 5, the projection 23 is brought into a pressure-contact state by screwing the fixing screw 31 into the mounting screw hole 46 of the nut body 3, and the end cap 4, the oil supply member 6, the oil-containing member 5, and the cap 7 are fixed to the nut body 3. Since the convex portion 23 of the oil supply member 6 is attached in pressure contact with the end surface 45 of the oil-containing member 5, the lubricant immersed in the oil-containing member 5 can smoothly move to the oil supply member 6, and the lubricant immersed in the oil-containing member 5 can be reliably and smoothly supplied to the oil supply member 6. In addition, the end surface 21 on one side of the oil supply member 6 contacts the balls 9 rolling in the direction change path 14, thereby supplying the lubricant to the balls 9; the other end surface 22 of the oil supply member 6 is configured to be pressed against the oil-containing member 5, so that the lubricant is supplied to the oil supply member 6. The oil supply member 6 is flat, and the end surface 21 exposed to the direction change path 14 is formed into an R-shaped arc surface that is substantially rectangular and extends in the longitudinal direction, and the width of the end surface 21 of the oil supply member 6 is set within the range of 1/4 to 1/2 that is substantially equal to the diameter of the balls 9, whereby the oil supply member 6 can supply an appropriate amount of lubricant to the balls 9.

The oil-impregnated member 5 and the oil-supplying member 6 are formed of a porous molded body formed by compacting and then thermoforming fine particles of a synthetic resin of polyethylene or polypropylene and having porous portions in which the fine particles of the synthetic resin are kept in a state of being communicated with each other, and the porous portions are impregnated with the lubricant. Thus, in this ball screw, since the oil supply member 6 is exposed in the direction change path 14, the balls 9 rolling in the direction change path 14 contact the end surface 21 of the oil supply member 6, the lubricant impregnated in the oil-containing member 5 and the oil supply portion 6 can be supplied to the balls 9, and the effect of lubrication-free maintenance can be achieved. In addition, regarding the ball screw, for example, the parameters of the ball screw may be set so that the axial diameter of the screw shaft 1 is Φ 15, the spiral groove 11 formed in the outer peripheral surface 10 of the screw shaft 1 may be formed in one row, and the lead may be set to 30 mm.

Claims

1. A ball screw is characterized in that,

it has the following components: a rotatable screw shaft having a first spiral groove formed in a spiral shape in an axial direction on an outer peripheral surface thereof, the first spiral groove being formed to allow a plurality of balls as rolling elements to roll; and a cylindrical nut fitted to the outer peripheral surface of the screw shaft and having a second spiral groove formed on an inner peripheral surface thereof in a spiral shape in an axial direction, the second spiral groove facing the first spiral groove and allowing the balls to roll;

it is constituted as follows: the nut moves relatively on the screw shaft along the length direction along with the rotation of the screw shaft;

the nut includes: a cylindrical nut body in which the second spiral groove and a return path extending in the axial direction along which the balls roll are formed; end caps which are respectively arranged at both ends of the nut body and which are formed with a direction changing path that communicates the spiral track formed by the first spiral groove and the second spiral groove with the return path; an oil-containing member disposed on an outer end surface of the end cap and impregnated with a lubricant; and an oil supply member disposed in a communication hole formed in the end cap and communicating the direction change path with the outer end surface of the end cap on the oil-containing member side;

the convex portion of the oil supply member is disposed in contact with the end surface of the oil-containing member on the end cover side,

2. The ball screw of claim 1,

the nut is provided with a cover for covering an outer surface of the oil-containing member, and the cover is fixed to the nut body with the end cover and the oil-containing member interposed therebetween.

3. The ball screw of claim 2,

the oil-containing member is accommodated in the cap disposed on the outer end surface of the end cap, and is formed in a C-shaped ring shape so as to align with a sealing protrusion provided on the cap.

4. The ball screw of claim 1,

the nut body has a flange portion formed with an attachment hole for attaching an engaging member.

5. The ball screw of claim 1,

the ball rolls in a circulation path including the spiral track, the return path, and the direction change path as the screw shaft rotates, and the nut is relatively moved in the longitudinal direction on the screw shaft by the ball.

6. The ball screw of claim 1,

the screw shaft is a ball screw shaft of a round shaft type in which both end portions are rotatably supported.

7. The ball screw of claim 1,

the communication hole formed in the end cover opens on an outer wall surface of the direction change path that is bent into an R-shape, and the other end surface of the oil supply member exposed in the direction change path is formed into the same shape of the outer wall surface that is bent into an R-shape.

8. The ball screw of claim 1,

the width of the other end surface of the oil supply member exposed in the direction change path is set within the range of 1/4-1/2 of the diameter of the ball.

9. The ball screw of claim 1,

the end cap is an internal return plate formed with a convex portion of the direction change path communicating the spiral track and the return path and a click claw for catching the ball on the spiral track side, and the convex portion of the internal return plate is fitted into a concave portion formed on each end portion of the nut main body and communicating with each end portion of the second spiral groove.

10. The ball screw of claim 1,

the oil-containing member and the oil-supplying member are formed of a porous molded body formed by compacting and then thermoforming fine synthetic resin particles of polyethylene or polypropylene and having porous portions that maintain communication between the fine synthetic resin particles, and the porous portions are impregnated with the lubricant.