WO2015046033A1

WO2015046033A1 - Linear motor actuator with ball spline and method for manufacturing same

Info

Publication number: WO2015046033A1
Application number: PCT/JP2014/074797
Authority: WO
Inventors: 山中　修平
Original assignee: Thk株式会社
Priority date: 2013-09-25
Filing date: 2014-09-19
Publication date: 2015-04-02
Also published as: CN105594109B; KR101666340B1; TWI547068B; KR20160039294A; CN105594109A; JP2015065757A; DE112014004441T5; DE112014004441B4; TW201530987A; JP5786007B2

Abstract

Provided is a linear motor actuator with a ball spline, in which the traveling parallelism of a spline shaft with respect to an attachment surface of the main body of a linear motor can be improved. The linear motor actuator with the ball spline according to the present invention comprises: a linear motor (1) in which a drive shaft (3) moves linearly with respect to a main body portion (2); a ball spline (4) having a spline shaft (6) and a nut (5) and integrating the nut (5) and a housing on which an attachment portion (34) through which the housing is attached to the other party's component is formed, said spline shaft (6) being disposed in parallel with the drive shaft (3) of the linear motor (1) and apart therefrom by a predetermined distance, said nut (5) being assembled to the spline shaft (6) via a large number of balls (38) so as to be movable in a shaft direction; a first coupling member (8) fixed to the main body portion (2) of the linear motor (1) and also fixed to the nut (5) of the ball spline (4) by using the attachment portion (34); and a second coupling member (9) fixed to the drive shaft (3) of the linear motor (1) and also fixed to the spline shaft (6) of the ball spline (4).

Description

Linear motor actuator with ball spline and manufacturing method thereof

The present invention relates to a linear motor actuator with a ball spline having a ball spline and a method for manufacturing the same.

The applicant has proposed a linear motor actuator with a ball spline described in Patent Document 1 as this type of linear motor actuator with a ball spline. As shown in FIG. 10, this linear motor actuator with a ball spline includes a linear motor 51 in which a drive shaft 53 linearly moves in the axial direction with respect to a main body 52, and a ball spline 47 arranged in parallel to the linear motor 51. Are used as, for example, a uniaxial actuator of a component mounter. The ball spline 47 is used to guide the linear motion of a moving body such as an electronic component with high accuracy. The drive shaft 53 of the linear motor 51 and the spline shaft 46 of the ball spline 47 are connected by a head plate 48. The nut 41 of the ball spline 47 is accommodated in the housing 43 and is connected to the main body 52 of the linear motor 51 via a connecting plate 49. When the drive shaft 53 of the linear motor 51 moves linearly, the spline shaft 46 of the ball spline 47 moves linearly together with the drive shaft 53 of the linear motor 51.

When using a linear motor actuator with a ball spline as a uniaxial actuator for a component mounting machine, the main body 52 of the linear motor 51 is mounted on the component mounting machine. An attachment surface 52 a that is attached to the component mounting machine is formed on the main body 52 of the linear motor 51. A suction pad (not shown) for sucking a moving body such as an electronic component is provided at the tip of the spline shaft 46. The moving body linearly moves in one axial direction with the mounting surface 52a of the main body 52 of the linear motor 51 as a reference surface. The main body 52 of the linear motor 51 is also provided with a sliding bearing such as a bush. However, since it is a sliding bearing, the accuracy of guiding the linear motion of the moving body cannot be increased so much. In order to improve the guidance accuracy, a ball spline 47 that guides using the rolling motion of the ball is used.

JP 2010-57357 A

By the way, in the conventional linear motor actuator with ball spline, as shown in FIG. 11, the nut 41 of the ball spline 47 is inserted into the hole of the housing 43 and adhered to the hole of the housing 43 using an adhesive. However, there is a possibility that the nut 41 of the ball spline 47 is inclined by the amount of play of the clearance in the hole of the housing 43, so that the mounting accuracy of the nut 41 with respect to the mounting surface 52 a of the main body 52 of the linear motor 51 is difficult to obtain. Therefore, there is a problem that the running parallelism of the spline shaft 46 with respect to the mounting surface 52a of the linear motor 51 is lowered. Here, the running parallelism is a numerical value indicating the allowable range of the distance from the mounting surface 52a of the main body 52 of the linear motor 51 to the spline shaft 46 regardless of the position of the linearly moving spline shaft 46. It is shown by.

Accordingly, an object of the present invention is to provide a linear motor actuator with a ball spline that can improve the running parallelism of the spline shaft with respect to the mounting surface of the main body of the linear motor, and a method for manufacturing the same.

In order to solve the above-described problems, an aspect of the present invention includes a linear motor in which a drive shaft linearly moves with respect to a main body, and a spline shaft that is arranged in parallel with a predetermined distance from the drive shaft of the linear motor. And a spline shaft having a nut assembled so as to be relatively movable in the axial direction via a plurality of balls, and a ball spline integrated with a housing in which a mounting portion for mounting to a mating part is formed on the nut And a first connecting member fixed to the nut of the ball spline using the mounting portion, and fixed to the drive shaft of the linear motor. A linear motor actuator with a ball spline comprising: a second connecting member fixed to the spline shaft of the ball spline It is over data.

In another aspect of the present invention, a linear motor in which a drive shaft linearly moves with respect to a main body, a spline shaft arranged in parallel at a predetermined distance from the drive shaft of the linear motor, and a large number of spline shafts. A ball spline that has a nut assembled so as to be relatively movable in the axial direction via the ball of the ball and integrates a housing in which a mounting portion for mounting to a mating part is formed on the nut. Fixing the first connecting member to the main body portion of the linear motor and fixing the first connecting member to the nut of the ball spline using the mounting portion; and a second connecting member. Fixing the second connecting member to the spline shaft of the ball spline and fixing the second connecting member to the drive shaft of the linear motor. It is a manufacturing method of the linear motor actuator with Le splines.

According to the present invention, the nut of the ball spline and the housing in which the mounting portion for mounting to the mating part is integrated, and the nut is connected to the main body of the linear motor via the first connecting member. The mounting accuracy of the nut with respect to the mounting surface of the main body of the motor can be improved. Therefore, the running parallelism of the spline shaft with respect to the mounting surface of the main body portion of the linear motor can be improved.

The perspective view of the linear motor actuator with a ball spline of one embodiment of the present invention. The figure which shows the main-body part and nut of a linear motor fixed to the connection plate of this embodiment (FIG. 2 (a) shows a front view, FIG.2 (b) shows a side view) A perspective view of the linear motor of this embodiment (including a partial cross section) The perspective view of the ball spline of this embodiment FIG. 5A is a plan view of the ball spline of this embodiment, and FIG. 5B is a front view of the ball spline of this embodiment. Sectional drawing along the axial direction of the ball spline of this embodiment Sectional drawing orthogonal to the axial direction of the ball spline of this embodiment Schematic diagram of ball circulation path of ball spline of this embodiment The figure which compares the conventional linear motor actuator with a ball spline and the linear motor actuator with a ball spline of this embodiment (FIG. 9 (a1) (a2) shows a prior art example, FIG.9 (b1) (b2) shows this implementation Shows form) Perspective view of a conventional linear motor actuator with ball spline The figure which shows the nut accommodated in the housing of the conventional linear motor actuator with a ball spline

Hereinafter, a linear motor actuator with a ball spline according to an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a perspective view of a linear motor actuator with a ball spline according to this embodiment. The linear motor actuator with a ball spline according to the present embodiment includes a linear motor 1 and a ball spline 4 that is arranged in parallel at a predetermined distance from the linear motor 1.

The linear motor 1 includes a forcer 2 as a main body and a drive shaft 3 that moves linearly with respect to the forcer 2. The forcer 2 of the linear motor 1 is formed with an attachment surface 2a for attachment to a component mounter or the like. A female screw 7 is embedded in the mounting surface 2a. The ball spline 4 includes a nut 5 and a spline shaft 6 supported by the nut 5 so as to be linearly movable. The forcer 2 of the linear motor 1 and the nut 5 of the ball spline 4 are connected by a connecting plate 8 as a first connecting member. The drive shaft 3 of the linear motor 1 and the spline shaft 6 of the ball spline 4 are connected by a head plate 9 as a second connecting member.

A suction pad (not shown) for sucking a moving body such as an electronic component is provided at the tip of the spline shaft 6. When the drive shaft 3 of the linear motor 1 is linearly moved, the spline shaft 6 is linearly moved together with the drive shaft 3, and the moving body adsorbed on the suction pad is linearly moved. The position of the drive shaft 3 of the linear motor 1 is detected by a sensor 22. The linear motor actuator with a ball spline according to the present embodiment may be used as a single uniaxial actuator or may be used as a multi-axis actuator in combination of a plurality.

The head plate 9 is formed in a square plate shape. The connecting plate 8 is provided with a through hole 8a through which the drive shaft 3 passes. A slight clearance is provided between the inner peripheral surface of the through hole 8 a and the drive shaft 3 so as to allow linear movement of the drive shaft 3. The connecting plate 8 is provided with a through hole 8b through which the spline shaft 6 passes. An end cap 32a, which will be described later, is fitted into the through hole 8b. The connecting plate 8 is formed with a plurality of through holes through which the bolts 24 are passed. The connecting plate 8 is fixed to the forcer 2 of the linear motor 1 and the nut 5 of the ball spline 4 by connecting means such as a bolt 24.

FIG. 2 shows the forcer 2 of the linear motor 1 and the nut 5 of the ball spline 4 fixed to the connecting plate 8. FIG. 2 (a) shows these front views, and FIG. 2 (b) shows these side views. In FIG.2 (b), a part of nut 5 is shown with sectional drawing. The nut 5 includes a metal nut body 31 and a pair of

end caps

32 a and 32 b as a pair of lid members attached to both end surfaces of the nut body 31 in the axial direction. A seal 33 is attached to the outside of the

end caps

32 a and 32 b in order to prevent foreign matter from entering the inside of the nut body 31 and to hold the lubricant inside the nut body 31. When viewed in a cross section perpendicular to the axial direction, the nut body 31 has a quadrangular outer shape (see FIG. 1). The end caps 32a and 32b and the seal 33 are formed in a circular shape.

The nut body 31 is integrated with a housing in which a female thread 34 as an attachment portion is formed. That is, the nut main body 31 is a single part manufactured from a single material, and is not a two-part joined by bonding. One end surface 31 a in the axial direction of the nut body 31 is in contact with the connecting plate 8. An internal thread 34 for fixing the nut body 31 to the connecting plate 8 is formed on the end surface 31 a of the nut body 31. The bolt 24 is screwed into the female screw 34. When viewed from the axial direction of the nut main body 31, the female screw 34 is disposed at the four corners of the end surface 31a of the nut main body 31 having a quadrangular outer shape and outside the circular end cap 32a. The end cap 32 a protrudes in the axial direction from the end surface 31 a of the nut body 31 and enters the inside of the connection plate 8. The connecting plate 8 has a through hole 8b into which the end cap 32a and the seal 33 are inserted.

An end cap 32 b and a seal 33 are attached to the other end surface 31 b in the axial direction of the nut body 31. A cylindrical wall portion 31 c protrudes from the end surface 31 b of the nut body 31 in the axial direction. The wall portion 31 c is made of the same metal as the nut body 31 and is formed integrally with the nut body 31. The wall 31c surrounds the periphery of the cylindrical side surface of the end cap 31b. The tip end surface in the axial direction of the wall portion 31 c protrudes in the axial direction from the end surface of the seal 33. A female thread 36 is formed on the front end surface 31c1 of the wall portion 31c (see FIGS. 9B1 and 9B2). The female screw 36 is disposed at the four corners of the wall portion 31c having a rectangular outer shape and outside the end cap 32b having a circular outer shape.

The structure of the linear motor 1 is as follows. FIG. 3 is a perspective view (partially sectional view) of the linear motor 1 of the present embodiment. The drive shaft 3 includes a hollow rod 11 and a plurality of magnets 12 accommodated in the hollow space of the rod 11. The rod 11 is made of a nonmagnetic material such as stainless steel. The magnet 12 is formed in a cylindrical shape and is magnetized in the axial direction. A plurality of magnets 12 are arranged in the hollow space of the rod 11 so that the same poles face each other. A magnetic pole block 13 made of a magnetic material such as iron is interposed between the magnets 12.

The drive shaft 3 is surrounded by a plurality of coils 15 arranged in the center line direction. A magnetic clearance is interposed between the drive shaft 3 and the coil 15. The coil 15 is a copper wire spirally wound and is held by a coil holder 16. A substrate 17 for wiring to the plurality of coils 15 is provided on the upper surface of the coil holder 16. The coil 15, the coil holder 16, and the substrate 17 are covered with the forcer 2. The forcer 2 constitutes the main body of the linear motor 1. The forcer 2 is formed, for example, by insert molding in which the coil 15, the coil holder 16, and the substrate 17 are set in an injection mold and a molten resin or special ceramics is allowed to flow. The forcer 2 is formed with an attachment surface 2a for attachment to a component mounting machine. The mounting surface 2a is provided with a female screw 7 and a positioning recess into which a positioning pin is inserted.

End members

19a and 19b are provided at both ends in the center line direction of the forcer 2. The

end members

19a and 19b are provided with bushes 21 for guiding the drive shaft 3 to move in the axial direction. The bush 21 is made of resin. The drive shaft 3 slides on the inner peripheral surface of the bush 21. The bush 21 prevents the drive shaft 3 from contacting the coil 15 and has a role of interposing a magnetic clearance therebetween. One end member 19 a is formed with a female screw (not shown) for fixing the connecting plate 8. A sensor 22 (see FIG. 1) for detecting the position of the drive shaft 3 is attached to the other end member 19b.

In the hollow space in the rod 11, a plurality of columnar magnets 12 are arranged so that the same poles face each other, that is, the N pole and the N pole are opposed to each other. A plurality of coils 15 are stacked around the drive shaft 3. The coil 15 is a three-phase coil composed of U, V, and W phases. When a three-phase current having a phase shift of 120 ° is applied to the three-phase coil, thrust is generated on the drive shaft 3 due to the interaction between the magnetic flux generated on the drive shaft 3 and the current flowing on the three-phase coil. As a result, the drive shaft 3 moves in the axial direction with respect to the forcer 2.

The detailed structure of the ball spline 4 is as follows. FIG. 4 shows a perspective view of the ball spline 4. The ball spline 4 includes a spline shaft 6 and a nut 5 that is assembled to the spline shaft 6 through a large number of balls so as to be relatively movable in the axial direction. On the outer peripheral surface of the spline shaft 6, a plurality of spline grooves 6a extending in the axial direction in this embodiment are formed. The nut 5 includes a nut body 31 and

end caps

32 a and 32 b as lid members attached to both end surfaces of the nut body 31 in the axial direction. The nut body 31 has a quadrangular outer shape over the entire length of the nut body 31 in the axial direction.

5 (a) is a plan view of the ball spline 4, and FIG. 5 (b) is a front view of the ball spline 4 viewed from the axial direction. A pair of

end caps

32a and 32b are attached to both end faces 31a and 31b in the axial direction of the nut body 31 (see FIG. 6). One end cap 32 a is exposed from the nut body 31, and the other end cap 32 b is embedded in the wall portion 31 c of the nut body 31.

6 shows a cross-sectional view along the axial direction of the ball spline 4, and FIG. 7 shows a cross-sectional view orthogonal to the axial direction of the ball spline 4. As shown in FIG. 6, a ball rolling groove 35 facing the spline groove 6 a of the spline shaft 6 is formed in the nut body 31. As shown in FIG. 7, a ball return portion 36 is formed in the nut body 31 in parallel with the ball rolling groove 35. The ball return portion 36 also includes a groove facing the spline shaft 6. As shown in FIG. 6, the end caps 32 a and 32 b are formed with a U-shaped direction changing portion 37 that connects the end of the ball rolling groove 35 and the end of the ball return portion 36. As shown in FIG. 7, the direction changing portion 37 also includes a groove facing the spline shaft 6. As shown in FIG. 8, a large number of balls 38 are arranged in a ball circulation path including a ball rolling groove 35, a ball return portion 36, and a pair of direction changing portions 37.

When the spline shaft 6 moves linearly relative to the nut 5, the ball 38 rolls between the spline groove 6a and the ball rolling groove 35 while receiving a compressive load. The ball 38 rolled to one end of the ball rolling groove 35 enters the direction changing portion 37, is released from the load and turns 180 °, and moves the ball returning portion 36 in the opposite direction. Then, after entering the direction changing portion 37 on the opposite side, the ball enters the original ball rolling groove 35 again.

Referring to FIG. 9, the effect of the linear motor actuator with the ball spline of this embodiment will be described. 9 (a1) and 9 (a2) show a conventional linear motor actuator with a ball spline, and FIGS. 9 (b1) and 9 (b2) show a linear motor actuator with a ball spline of this embodiment. FIGS. 9A1 and 9B1 are side views of a linear motor actuator with a ball spline, and FIGS. 9A2 and 9B2 are front views.

<Running Parallelism> As shown in FIG. 9 (b 1), according to the linear motor actuator with ball spline of this embodiment, the nut 5 of the ball spline 4 and the housing are integrated, and the nut 5 is connected via the connecting plate 8. As a result, the running parallelism of the spline shaft 6 with respect to the mounting surface 2a of the forcer 2 of the linear motor 1 can be improved.

<Dimension> As shown in FIG. 9 (a1), the conventional linear motor actuator with ball spline requires a lid 42 to prevent the nut 41 from popping out. For this reason, the total length L of the housing 43 including the lid 42 is increased. On the other hand, as shown in FIG. 9 (b1), according to the linear motor actuator with the ball spline of this embodiment, the nut 5 itself is fixed to the connecting plate 8, so that a portion corresponding to the lid 42 is unnecessary. Become. And since the end cap 32a is embedded in the connection plate 8, the full length L of the nut 5 can be shortened. Furthermore, the nut body 31 has a cross-sectional outer shape formed in a square shape, and female screws 34 are formed in the four corners of the quadrilateral, so that the nut body 31 has a cross-sectional outer shape formed in a circular shape compared to the radial direction. The dimensions of can also be reduced.

<Assemblyability and maintainability> As shown in FIG. 9 (a1), in the conventional linear motor actuator with ball spline, when the nut 41 is inserted into the housing 43, the resin end cap 44 or the resin seal 45 contacts the metal connection plate 58. For this reason, the end cap 44 or the seal 45 is deformed, causing an increase in sliding resistance of the spline shaft 56 or affecting the movement of the spline shaft 56. On the other hand, as shown in FIG. 9 (b2), according to the linear motor actuator with the ball spline of this embodiment, the metal nut 5 is fixed to the connecting plate 8 with the bolts 24. The made

end caps

32a, 32b or the seal 33 do not come into contact with other parts. For this reason, the stability of assembly improves. Further, since it is not necessary to bond the nut 5 to the housing, the number of assembling steps can be greatly reduced. The nut 5 can be provided with a greasing hole that has been difficult in the prior art, and the nut 5 can be easily replaced even when it is broken.

<User Installation> As shown in FIG. 9 (a2), the conventional linear motor actuator with a ball spline requires a screw 46 for attaching the lid 42, so that it is attached for attaching other parts to the lid 42. Surfaces and female threads cannot be provided. On the other hand, as shown in FIG. 9 (b2), according to the linear motor actuator with the ball spline of the present embodiment, the end cap 32b and the seal 33 are embedded inside the wall portion 31c of the nut 5. The attachment surface and the internal thread 36 can be provided on the front end surface 31c1 of the wall portion 31c of the fifth wall portion 31c, so that the user can easily attach other components.

Note that the present invention is not limited to the embodiment described above, and can be embodied in various embodiments without changing the gist of the present invention.

For example, in the above embodiment, a coil is provided in the main body portion of the linear motor and a magnet is provided in the drive shaft. However, a magnet may be provided in the main body portion and a coil may be provided in the drive shaft.

In the above embodiment, only one end cap is surrounded by the nut wall, but both end caps may be surrounded by the nut wall. In this case, the tip end surface of the wall portion of the nut can be fixed to the connecting plate.

This specification is based on Japanese Patent Application No. 2013-198376 filed on September 25, 2013. All this content is included here.

DESCRIPTION OF SYMBOLS 1 ... Linear motor, 2 ... Forcer (body part), 2a ... Mounting surface, 3 ... Drive shaft, 4 ... Ball spline, 5 ... Nut, 6 ... Spline shaft, 6a ... Spline groove, 8 ... Connection plate (1st Connecting member), 9 ... head plate (second connecting member), 31 ... nut body, 31a, 31b ... end face of the nut body, 31c ... wall part of the nut body, 31c1 ... tip end face of the wall part of the nut body, 32a , 32b ... End cap, 34 ... Female screw (mounting part), 35 ... Ball rolling groove, 36 ... Ball return part, 38 ... Ball

Claims

A linear motor in which the drive shaft moves linearly with respect to the main body,
A spline shaft arranged in parallel with a predetermined distance from the drive shaft of the linear motor; and a nut assembled to the spline shaft so as to be relatively movable in the axial direction via a plurality of balls. A ball spline that integrates a housing in which a mounting portion for mounting to a mating part is formed;
A first connecting member fixed to the body portion of the linear motor and fixed to the nut of the ball spline using the attachment portion;
A linear motor actuator with a ball spline, comprising: a second connecting member fixed to the drive shaft of the linear motor and fixed to the spline shaft of the ball spline.
The nut is
A nut rolling body formed with a ball rolling groove facing the spline groove of the spline shaft, and a rolling element return portion parallel to the ball rolling groove;
A pair of lid members that are attached to both end surfaces of the nut body in the axial direction and in which a direction changing portion that connects an end portion of the rolling element rolling groove and an end portion of the rolling element return portion is formed; ,
The linear motor actuator with a ball spline according to claim 1, wherein the housing is integrated with the nut body.
The first connecting member is fixed to one end face of the both end faces of the nut body,
The one lid member of the pair of lid members protrudes in the axial direction from the one end surface of the nut body and enters the inside of the first connecting member. Linear motor actuator with ball spline.
The nut body is integrally provided with a wall portion protruding in an axial direction from at least one end face of the both end faces of the nut body so as to cover at least one of the pair of lid members. The linear motor actuator with a ball spline according to claim 2 or 3.
When the nut body is viewed in a cross section orthogonal to the axial direction,
The linear motor actuator with a ball spline according to claim 2 or 3, wherein an outer shape of a cross-sectional shape of the nut body is formed in a square shape.
The ball spline according to claim 2 or 3, wherein the mounting portion of the nut main body is provided on at least one end surface of the both end surfaces of the nut main body or a front end surface of the wall portion. Linear motor actuator.
A linear motor in which a drive shaft moves linearly with respect to the main body, a spline shaft arranged in parallel at a predetermined distance from the drive shaft of the linear motor, and a plurality of balls on the spline shaft in the axial direction A step of preparing a ball spline that has a nut that is assembled so as to be relatively movable, and that integrates a housing in which a mounting portion for mounting to a mating part is formed on the nut;
Fixing the first connecting member to the body portion of the linear motor, and fixing the first connecting member to the nut of the ball spline using the mounting portion;
Fixing the second connecting member to the drive shaft of the linear motor, and fixing the second connecting member to the spline shaft of the ball spline;
A method of manufacturing a linear motor actuator with a ball spline.