Actuator

Abstract

To provide an actuator that can secure an oil supply passage even if it is downsized.SOLUTION: An actuator comprises: a ball screw comprising a ball screw shaft 71, and a ball screw nut 72; a guide device comprising a slide part 31 holding the ball screw nut 72, rolling bodies to be rolled in a circulation passage, and a rail part 60 supporting the slide part 31 via the rolling bodies so as to allow linear motion; a working shaft 11 for performing linear motion; and a connection part 50 connecting the slide part 31 and the working shaft 11. Through holes 32a and 32c inside which the ball screw nut 72 and the cylindrical part 52 of the connection part 50 are fixed are formed in the slide part 31. An insertion hole 50a into which the ball screw shaft 71 is inserted is formed in the connection part 50. The cylindrical part 52 comprises a connection part side oil supply part provided with an oil supply passage for the insertion hole 50a and the circulation passage.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to an actuator. [Background technology]

[0002] An actuator is a mechanical device in which, for example, a ball screw converts the rotational motion of a motor into the linear motion of a slider. The slider is attached to a rail, for example, via a number of spherical rolling elements. The rolling elements roll, causing the slider to move smoothly in a linear motion along the rail. In such an actuator, lubricating oil is supplied to the rolling elements to ensure smooth movement of the slider relative to the rail.

[0003] Patent Document 1 discloses a technique for supplying lubricating oil to a rolling element and a ball screw through an oil supply passage formed in a slider. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-090176 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, when the actuator is made even smaller, the size of the sliding portion also becomes smaller, making it difficult to ensure an oil supply path for the lubricating oil.

[0006] The present invention has been made to solve the above-mentioned problems, and has an object to provide an actuator that can ensure an oil supply path even when it is miniaturized. [Means for solving the problem]

[0007] The actuator according to the present invention comprises: a ball screw having a ball screw shaft rotated by a motor and a ball screw nut that moves linearly in association with the rotational motion of the ball screw shaft; a slide section that holds the ball screw nut, rolling bodies that roll in a circulation path, and a rail section that supports the slide section so that it can move linearly via the rolling bodies; a work shaft that moves linearly together with the slide section; and a connecting section that connects the slide section and the work shaft, wherein the slide section has a through hole that penetrates in the linear motion direction in which the slide section moves linearly and into which the fitting section of the ball screw nut and the connecting section is fixed, the connecting section has an insertion hole through which the ball screw shaft is inserted, and at least a part of the inner surface of the insertion hole has a female threaded section that screws into a male threaded section formed on the work shaft, and the fitting section has a connecting section side oil supply section in which an oil supply path to the insertion hole and the circulation path is provided.

[0008] The connection portion side oil supply portion may have a first through hole portion penetrating from the outer periphery of the fitting portion to the insertion hole, and the first through hole portion may be connected to a second through hole portion penetrating from the outer periphery of the sliding portion to the through hole.

[0009] The connecting portion side oil supply portion has an outer peripheral groove portion formed on the outer peripheral surface of the fitting portion, and the slide portion has a second through hole portion penetrating from the outer periphery of the slide portion to the through hole, and a slide portion side oil supply portion in which an oil supply path is provided from the through hole to the circulation path, and the outer peripheral groove portion may connect the second through hole portion and the slide portion side oil supply portion.

[0010] A return portion for redirecting the rolling elements may be attached to both ends of the slide portion, and a part of the slide portion-side oil supply portion may be provided on the return portion.

[0011] A portion of the slide portion-side oil supply portion provided in the return portion may be formed by a recess provided in a contact surface of the return portion that contacts the slide portion.

[0012] The connecting portion may be spigot-connected to the sliding portion by fitting the fitting portion into the through hole. Effect of the Invention

[0013] According to the present invention, it is possible to provide an actuator that can ensure an oil supply path even when it is miniaturized. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a perspective view of an actuator according to an embodiment of the present invention. [Diagram 2] FIG. 2 is an exploded perspective view showing a state in which a cover of the actuator according to the embodiment of the present invention is removed. [Diagram 3] FIG. 2 is an exploded perspective view of the actuator according to the embodiment of the present invention. [Figure 4] FIG. 2 is an exploded cross-sectional view of the actuator according to the embodiment of the present invention. [Diagram 5] FIG. 4 is an exploded perspective view of the sliding portion shown in FIG. [Figure 6] 1A and 1B show a state in which the motor unit has been removed from the actuator according to the embodiment of the present invention, where (a) is a plan view and (b) is a cross-sectional view taken along the section line BB in (a). [Figure 7] FIG. 7 is an enlarged view of part “VII” in FIG. [Figure 8] 8 is a cross-sectional view taken along the cross-sectional line VIII-VIII in FIG. 7. [Figure 9] 9 is a cross-sectional view partially taken along the cross-sectional line IXa-IXa in FIG. 8 and partially taken along the cross-sectional line IXb-IXb in FIG. 8. [Figure 10] 6A and 6B are diagrams showing the first return portion shown in FIG. 5, where (a) is a front view, and (b) and (c) are perspective views. [Figure 11] 6A and 6B are perspective views showing the connecting portion shown in FIG. 5, (a) and (b) are perspective views, (c) is a front view seen from the arrow C in (a), and (d) is a front view seen from the arrow D in (b). [Figure 12]4 is an exploded perspective view for explaining attachment of the ball screw shown in FIG. 3 to a guide device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The actuator 10 according to the embodiment of the present invention will be described below. The actuator 10 in the figure is shown when used in a horizontally laid state, the XY plane in the figure is a horizontal surface, and the Z axis direction in the figure is a vertical direction.

[0016] 1, the actuator 10 is a linear actuator having a rod 11 (working shaft) that reciprocates in the Y-axis direction. The actuator 10 has the rod 11, a motor unit 20, a front housing 80, a bearing housing 90, and a cover 18.

[0017] The cover 18 is formed, for example, by extruding aluminum. As shown in Fig. 2, the cover 18 has a through hole 18a penetrating in the Z-axis direction, and is fixed to the front housing 80 and the bearing housing 90 by bolts 19.

[0018] As shown in FIG. 3, in addition to the rod 11, the actuator 10 has a guide device 30 that guides the rod 11 in the Y-axis direction, and a ball screw 70 that converts the rotational motion of the motor unit 20 into linear motion.

[0019] 4, rod 11 is a cylindrical member with hole 11a formed therein, and is made of, for example, stainless steel. A tip fitting 12 having a male thread formed on its outer periphery is fixed to the end of rod 11 on the -Y side. In addition, a male thread portion 11b is formed on the outer periphery of the end of rod 11 on the +Y side.

[0020] The motor unit 20 has a motor 21, a motor housing 22 that houses the motor 21, and an actuator cable 24.

[0021] The motor 21 is, for example, a stepping motor, and has an output shaft 23, a rotor, a stator, an encoder, and the like. Electricity is supplied to the motor 21 from a power source via an actuator cable 24. When electric power is supplied to the motor 21, the rotor of the motor 21 rotates. The rotational motion of the rotor is output to the output shaft 23. In addition, the tip of the output shaft 23 is configured as a coupling (joint). Note that the rotational motion of the rotor may be decelerated by a reducer and output to the output shaft 23.

[0022] The motor housing 22 is a substantially rectangular parallelepiped case, and an opening 22a is formed on the -Y side surface of the motor housing 22. The output shaft 23 of the motor 21 is exposed to the outside from this opening 22a. Furthermore, a screw hole 22b penetrating in the Z direction is formed on the upper side (+Z side) of the opening 22a. A bolt 25 is inserted into this screw hole 22b.

[0023] As shown in Fig. 3, the guide device 30 guides the rod 11 in both +Y and -Y directions by fixing the rod 11 to a connecting portion 50. The guide device 30 has a slide portion 31, a rail portion 60, and a connecting portion 50 that connects the slide portion 31 and the rod 11. Also, as shown in Fig. 5, the guide device 30 has a plurality of balls 85 (rolling elements) some of which are arranged between the slide portion 31 and the rail portion 60. The balls 85 are made of a highly rigid material, such as steel balls.

[0024] The slide portion 31 is supported by the rail portion 60 (FIG. 3) via balls 85 so as to be movable along the Y-axis which is the linear motion direction. The slide portion 31 has a slide portion main body 32, two lubricating oil pipes 66 provided on the slide portion main body 32, and return portions 40 provided on each of the +Y side end and -Y side end of the slide portion main body 32.

[0025] The sliding section body 32 is made of a metal such as steel. As shown in Fig. 8, a cross section of the sliding section body 32 cut in a direction perpendicular to the Y axis is convex-shaped, and the shape and size are constant along the Y axis. That is, the sliding section body 32 has a large cross-sectional portion 33 and a small cross-sectional portion 34 protruding from the -Z side surface of the large cross-sectional portion 33. The sliding section body 32 is supported by the rail section 60 via a ball 85 with the small cross-sectional portion 34 inserted into the opening of the rail section 60 having a U-shaped cross section.

[0026] 7, three holes 32a, 32b, 32c of different sizes are formed continuously in this order from the -Y side to the +Y side in the sliding portion main body 32. As a result, a through hole penetrating the sliding portion main body 32 on the Y axis is formed, which is composed of the three holes 32a, 32b, 32c.

[0027] Medium diameter hole 32a is formed on a surface facing the -Y side of slide portion main body 32. Cylindrical portion 52 of connecting portion 50 is fitted into medium diameter hole 32a from the -Y side.

[0028] The large diameter hole 32c is formed on a surface facing the +Y side of the slide portion main body 32. A ball screw nut 72 is fitted into the large diameter hole 32c from the +Y side.

[0029] The small diameter hole 32b is a through hole that connects the medium diameter hole 32a and the large diameter hole 32c. A ball screw shaft 71 is inserted into the small diameter hole 32b.

[0030] As shown in FIG. 8, recesses 34a, 34a extending in the Y-axis direction are formed on the surface facing the +X side and the surface facing the -X side of the small cross-section portion 34 over the entire length of the slide portion main body 32. Steel members 35, 35 formed in a substantially rectangular parallelepiped with the Y-axis direction as the longitudinal direction are attached to the recesses 34a, 34a. Grooves 35a, 35a are formed on the surface facing the outside of the steel members 35, 35. The grooves 35a, 35a are formed so as to face the grooves 65a, 65a of the steel members 65, 65 provided on the rail portion 60. The inner surfaces of the grooves 35a, 35a are configured as substantially curved surfaces. For example, the inner surface of the groove 35a is formed in a Gothic arch shape consisting of two arcuate portions. However, the present invention is not limited to this, and the inner surface of the groove 35a may be formed as a curved surface whose radius of curvature is equal to the radius of the ball 85. The space between the grooves 35a, 35a of the steel members 35, 35 and the grooves 65a, 65a of the steel members 65, 65 forms the straight passages 43a, 43a as a part of the circulation path of the balls 85. The straight passages 43a, 43a are provided on the side of the slide portion main body 32, and are one of the two straight passages of the ball circulation paths 43, 43 formed in an elliptical shape as shown in FIG. 9. In the cross-sectional view shown in FIG. 9, the left and right sides of the boundary between the slide portion main body 32 and the return portion 40 are cut at different positions. The right side is cut at the cross-sectional line IXa-IXa in FIG. 8, and this cut position is at the height position of the horizontal pull hole portion 38. On the other hand, the left side is cut at the cross-sectional line IXb-IXb, and this cut position is at the height position of the circulation path 43 in which the balls 85 roll.

[0031] Further, a part of an oil supply passage is formed in the slide portion main body 32 for supplying lubricating oil to the ball screw shaft 71 and the balls 85. The entire configuration of this oil supply passage will be described later, and first only the oil supply passage formed in the slide portion main body 32 will be described.

[0032] 7, the slide portion main body 32 is formed with a circular through-hole portion 36 extending in the Z-axis direction, penetrating from the outer circumferential surface facing the +Z side to the medium diameter hole 32a. The through-hole portion 36 as a second through-hole portion can be viewed by removing the cover 18 of the actuator 10 as shown in FIG. 2, and is used as an oil supply path 2a through which lubricating oil flows after it is injected.

[0033] Further, a circular vertical hole 37 extending in the -Z-axis direction from the inner wall of the medium diameter hole 32a is formed in the sliding portion main body 32. As shown in Fig. 8, the vertical hole 37 extends to approximately the center in the Z-axis direction of the small cross-section portion 34. The vertical hole 37 functions as an oil supply passage 2c through which the lubricating oil flows.

[0034] 7, the slide portion main body 32 is formed with a horizontal hole portion 38 that extends from the end face on the -Y side of the small cross-section portion 34 to the +Y side and is connected to the vertical hole portion 37. The vertical hole portion 37 and the horizontal hole portion 38 are substantially perpendicular to each other. The horizontal hole portion 38 functions as an oil supply passage 2d through which the lubricating oil flows.

[0035] 8, a pair of through holes 34b, 34b penetrating in the Y-axis direction are formed in the small cross-section portion 34 of the slide portion main body 32, on the inside of the recesses 34a, 34a. The positions of the pair of through holes 34b, 34b in the Z-axis direction are the same as the positions of the straight passage portions 43a, 43a in the Z-axis direction. When the slide portion main body 32 is viewed from the Y-axis, the pair of through holes 34b, 34b are provided at positions symmetrical with respect to a center line of the slide portion main body 32 parallel to the Z-axis. A lubricating oil pipe 66 is inserted into each of the through holes 34b, 34b.

[0036] The lubricating oil pipe 66 is formed in a cylindrical shape, and its outer diameter is approximately the same as the inner diameter of the through hole 34b. The lubricating oil pipe 66 is fitted into the through hole 34b. The through hole 66a of the lubricating oil pipe 66 forms straight passage portions 43b, 43b that are part of the pair of circulation paths 43, 43 as a passage through which the ball 85 passes, as shown in FIG. 9. The straight passage portions 43b, 43b are formed inside the slide portion main body 32, and are parallel to the other straight passage portions 43a, 43a.

[0037] The lubricating oil pipe 66 shown in Fig. 5 is, for example, a sintered resin member having a porous structure. The lubricating oil pipe 66 is formed by filling a mold with ultra-high molecular weight polyethylene powder, compressing it, and heating it. The lubricating oil pipe 66 retains the lubricating oil due to its porous structure. As a result, the lubricating oil is supplied to the ball 85 by passing through the through hole 66a of the lubricating oil pipe 66.

[0038] 5, the return portion 40 has a first return portion 41 and a second return portion 42 that is combined with the first return portion 41. The return portion 40 is attached to the slide portion main body 32 by fastening bolts 57, 57 that pass through the first return portion 41 and the second return portion 42 into screw holes 34c, 34c formed in the small cross-section portion 34.

[0039] The return portion 40 is attached to both ends of the slide portion main body 32 in the Y-axis direction. In the return portion 40 provided on the end face on the -Y side of the slide portion main body 32, a pair of curved passage portions 43c, 43c that are part of a pair of circulation paths 43 are formed as a passage for the ball 85, as shown in FIG. 9. In addition, in the return portion 40 provided on the end face on the +Y side of the slide portion main body 32, a pair of curved passage portions 43d, 43d are formed. Each of the curved passage portions 43c, 43d is formed in an arc shape. One end of the curved passage portions 43c, 43d is connected to the straight passage portion 43a, and the other end is connected to the straight passage portion 43b. This forms the oval-shaped circulation paths 43, 43. The curved passage portions 43c, 43d redirect the ball 85 that has rolled from one of the straight passage portions 43a, 43b toward the other of the straight passage portions 43a, 43b. The basic configuration of return portion 40 provided on the end face on the +Y side of slide portion main body 32 is the same as the basic configuration of return portion 40 provided on the end face on the -Y side. Therefore, the basic configuration of return portion 40 provided on the end face on the -Y side will be described below.

[0040] The second return portion 42 has a gate-shaped shape as shown in the enlarged view of FIG. 5, and includes a pair of legs 42a, 42a and a cross member 42b connecting the ends of the pair of legs 42a, 42a. A curved portion 42c is formed on the edge of the cross member 42b on the +Z side to prevent the medium diameter hole 32a formed in the slide portion main body 32 from being blocked. A bolt insertion hole 42d through which the bolt 57 is inserted is formed on both sides of the second return portion 42. In addition, curved inner wall portions 42e, 42e that form the inside of the curved passage portion 43c are formed on the outer peripheral surfaces of the pair of legs 42a, 42a of the second return portion 42. The curved inner wall portions 42e, 42e are formed over approximately half of the outer peripheral surfaces of the legs 42a, 42a, and are formed in a groove shape that generally matches the outer shape of the ball 85.

[0041] As shown in Fig. 10(a), the first return part 41 has a configuration symmetrical with respect to a center line CL extending in the Z-axis direction when viewed from the front. As shown in Fig. 5, the first return part 41 is attached to the lower part of the sliding part main body 32 in the drawing. The length of the first return part 41 in the Z-axis direction is approximately the same as the length of the small cross-section part 34 in the Z-axis direction. A curved part 41a is formed on the edge part on the +Z side of the first return part 41 to prevent blocking of the medium diameter hole 32a. On both sides of the first return part 41, a bolt insertion hole 41b is formed through which the bolt 57 is inserted. Also, as shown in Figures 10(a) to 10(c), the surface of the first return portion 41 facing the small cross-section portion 34 is formed with alignment protrusions 45, 45, recesses 41c, 41c into which the legs 42a, 42a of the second return portion 42 are fitted, and a bracket 41d that supports the center of the cross member 42b of the second return portion 42 from below (-Z side).

[0042] 5, when the return portion 40 is attached to the sliding portion main body 32, the protrusions 45, 45 are inserted into the insertion holes 34d, 34d formed in the sliding portion main body 32. This allows the return portion 40 to be aligned with the sliding portion main body 32.

[0043] The recesses 41c, 41c are rectangular as shown in Fig. 10(b). The second return part 42 shown in Fig. 5 is combined with the first return part 41 by fitting the legs 42a, 42a into the recesses 41c, 41c and supporting the cross member 42b on the bracket 41d.

[0044] 10(a), curved outer wall portions 41e, 41e that form the outside of the curved passage portion 43c are formed on the surface of the first return portion 41 facing the small cross-sectional portion 34. The curved outer wall portions 41e, 41e are provided symmetrically with respect to the center line CL of the first return portion 41, and form the curved passage portions 43c, 43c together with the curved inner wall portions 42e, 42e of the second return portion 42. The curved outer wall portions 41e, 41e are formed with a groove-shaped portion that generally matches the outer shape of the ball 85 and extends in an arc shape.

[0045] 9, between the first return portion 41 and the slide portion main body 32, oil supply passages 2e, 2f, 2f are formed to guide the lubricating oil from the oil supply passage 2d to the circulation passages 43, 43 formed on both sides (±X side). These oil supply passages 2e, 2f, 2f are formed between the slide portion main body 32 and recesses 46, 47, 47 formed on the contact surface 41f of the first return portion 41 with the slide portion main body 32 (FIG. 5), as shown in FIG. 10(a). In this way, the slide portion 31 has a slide portion side oil supply portion in which the oil supply passages 2c, 2d, 2e, 2f, 2f are provided from the through hole of the slide portion main body 32 to the circulation passage 43.

[0046] As shown in Fig. 10(a), the recess 46 is a circular recess formed at the same position as the horizontal hole 38 formed in the sliding portion main body 32. The lubricating oil flowing from the oil supply passage 2d collides with the recess 46, changing the flow direction of the lubricating oil. An oil supply passage 2e is formed in the gap between the recess 46 and the sliding portion main body 32 (Fig. 9).

[0047] The recesses 47, 47 connect the recess 46 to the curved outer wall portions 41e, 41e formed on both sides thereof. The extension direction of the recesses 47, 47 is toward the -Z side from the recess 46 toward the curved outer wall portions 41e on both sides, that is, the recesses 47, 47 are inclined with respect to the X-axis. The oil supply passages 2f, 2f are formed in the gap between the recesses 47, 47 and the sliding portion main body 32 (FIG. 9).

[0048] As shown in FIG. 3, the rail portion 60 has a plate-shaped base 61 with the Y-axis direction as the longitudinal direction, and side walls 62, 62 erected on the +X side and -X side of the base 61. As a result, the cross section of the rail portion 60 cut in a direction perpendicular to the Y-axis is U-shaped as shown in FIG. 8. The rail portion 60 is formed, for example, by extruding aluminum. In addition, recesses 62a, 62a are formed on the inner surfaces of the side walls 62, 62. Steel members 65, 65 formed in a substantially rectangular parallelepiped with the Y-axis direction as the longitudinal direction are attached to the recesses 62a, 62a. A groove portion 65a is formed on each of the inner surfaces of the steel members 65, 65. The groove portions 65a, 65a are formed to face each other, and the inner surfaces of the groove portions 65a, 65a are configured as substantially curved surfaces. For example, the inner surface of the groove portion 65a is formed in a Gothic arch shape consisting of two arc portions. However, the present invention is not limited to this, and the inner surface of the groove portion 65a may be formed into a curved surface whose radius of curvature is equal to the radius of the ball 85.

[0049] As shown in Fig. 3, the slide portion 31 is attached to the rail portion 60 via a plurality of balls 85 (Fig. 5). When the slide portion 31 is attached to the rail portion 60, the balls 85 (Fig. 5) are sandwiched between the groove portions 65a, 65a of the steel members 65, 65 of the rail portion 60 and the groove portions 35a, 35a of the steel members 35, 35 of the slide portion main body 32, as shown in Fig. 8. As a result, the slide portion main body 32 is supported by the rail portion 60 only by the balls 85, and becomes movable in the Y-axis direction relative to the rail portion 60.

[0050] 7, the connecting portion 50 is interposed between the sliding portion main body 32 and the rod 11 to connect them together. As a result, the rod 11 moves together with the sliding portion main body 32 in the Y-axis direction.

[0051] As shown in Figs. 11(a) and 11(b), the connecting portion 50 has a substantially rectangular parallelepiped block portion 51 and a cylindrical portion 52 protruding in the +Y direction from the +Y side surface of the block portion 51. A through hole 50a is formed in the connecting portion 50, penetrating the block portion 51 and the cylindrical portion 52. As shown in Figs. 7 and 11(a), a female screw portion 50b is formed on the inner peripheral surface of the through hole 50a near the opening on the -Y side. As shown in Fig. 7, the male screw portion 11b of the rod 11 is screwed into the female screw portion 50b from the -Y side. As a result, the rod 11 is fixed to the connecting portion 50. The through hole 50a serves as an insertion hole through which the ball screw shaft 71 is inserted.

[0052] 7, the cylindrical portion 52 is a fitting portion that is fitted into the medium diameter hole (through hole) 32a of the sliding portion main body 32. The outer diameter of the cylindrical portion 52 is approximately the same as the hole diameter of the medium diameter hole 32a, preventing the cylindrical portion 52 fitted into the medium diameter hole 32a from rattling. In this manner, the connecting portion 50 is spigot-connected to the sliding portion main body 32 by fitting the cylindrical portion 52, which is a convex portion, into the medium diameter hole 32a, which is a concave portion.

[0053] As shown in FIG. 11(a) and FIG. 11(b), an outer circumferential groove portion 53 is formed around the center of the outer circumferential surface of the cylindrical portion 52 in the Z-axis direction. The cross section of the outer circumferential groove portion 53 is rectangular as shown in FIG. 7. When the cylindrical portion 52 is inserted into the medium diameter hole 32a, an oil supply passage 2b through which the lubricating oil flows is formed between the outer circumferential groove portion 53 and the inner circumferential surface of the medium diameter hole 32a. As shown in FIG. 8, the oil supply passage 2b is formed so as to surround the periphery of the cylindrical portion 52. Note that, as shown in FIG. 7, the positions of the oil supply passage 2a, the oil supply passage 2b, and the oil supply passage 2c on the Y-axis are aligned with each other. Therefore, the oil supply passage 2b formed around the cylindrical portion 52 communicates the oil supply passage 2a with the oil supply passage 2c. As a result, the lubricating oil from the oil supply passage 2a passes through the oil supply passage 2b, and a part of it can flow into the oil supply passage 2c.

[0054] 11(a) and 11(b), the cylindrical portion 52 is provided with a circular through hole portion 54 extending in the Z-axis direction from the outer circumferential groove portion 53 to the through hole 50a. As shown in FIG. 8, the through hole portion 54 as the first through hole portion functions as an oil supply passage 2g through which the lubricating oil flows. The through hole portion 54 communicates the oil supply passage 2b formed around the cylindrical portion 52 with the through hole 50a. The through hole portion 54 is formed at a position facing the oil supply passage 2c formed in the slide portion main body 32 across the oil supply passage 2b. Therefore, a part of the lubricating oil that has passed through the oil supply passage 2b flows into the oil supply passage 2c, and the remaining part flows into the inside of the through hole 50a via the oil supply passage 2g. In this way, the cylindrical portion 52 has a connecting portion side oil supply portion in which the oil supply passages 2b and 2g to the through hole 50a and the circulation passage 43 are provided.

[0055] 11(c) and 11(d), four bolt insertion holes 55 are formed around the through hole 50a in the block portion 51 of the connecting portion 50 in the Y-axis direction. As shown in FIG. 3, the connecting portion 50 is attached to the sliding portion main body 32 by fastening the bolts 56 inserted into the bolt insertion holes 55 to the screw holes 39 formed in the surface of the sliding portion main body 32 facing the -Y side.

[0056] As shown in FIGS. 3, 4, and 6, the ball screw 70 has a ball screw shaft 71, a ball screw nut 72, and an elastic member 110 attached to the end of the ball screw shaft 71 on the -Y side.

[0057] As shown in Fig. 4 and Fig. 6, the ball screw shaft 71 is composed of a ball screw shaft main body 71a whose outer circumferential surface is configured as a helical ball screw surface, and small diameter portions 71b, 71c formed at the +Y side end and the -Y side end of the ball screw shaft main body 71a, respectively. The small diameter portions 71b, 71c have a smaller diameter than the diameter of the ball screw shaft main body 71a. An elastic member 110 is fitted into the small diameter portion 71c of the ball screw shaft 71 and is prevented from coming off by a retaining member 112. In this way, the elastic member 110 is rotatably attached to the ball screw shaft 71.

[0058] The ball screw nut 72 is disposed on the outer periphery of a ball screw shaft main body 71a of the ball screw shaft 71. A ball screw portion is formed on the inner circumferential surface of the ball screw nut 72. The ball screw nut 72 is fitted onto the ball screw shaft 71 via a rigid sphere. This converts the rotational motion of the ball screw shaft 71 into the linear motion of the ball screw nut 72.

[0059] 3 and 4, a bearing 75 and a coupling 76 are attached to the small diameter portion 71b of the ball screw shaft 71. The bearing 75 is, for example, a ball bearing. The coupling 76 is fitted with the output shaft 23 of the motor unit 20. As a result, the rotational motion of the output shaft 23 is transmitted to the ball screw shaft 71.

[0060] The elastic member 110 is made of, for example, resin and is formed in a ring shape with a through hole formed in the center. The outer diameter of the elastic member 110 is formed to be almost equal to the inner diameter of the hole 11a of the rod 11. Specifically, when the small diameter portion 71c of the ball screw shaft 71 is inserted into the hole 11a of the rod 11, the outer periphery of the elastic member 110 is formed to contact the inner periphery of the hole 11a as shown in FIG. 6. By the outer periphery of the elastic member 110 contacting the inner periphery of the hole 11a, the elastic member 110 can suppress the vibration of the small diameter portion 71c of the ball screw shaft 71. That is, the elastic member 110 functions as a vibration prevention member that suppresses the vibration of the small diameter portion 71c of the ball screw shaft 71.

[0061] The ball screw 70 is fixed to the guide device 30 as shown in Fig. 12. Specifically, the -Y side end of the ball screw shaft 71 is inserted through the large diameter hole 32c of the slide portion main body 32, and the ball screw nut 72 is accommodated in the large diameter hole 32c. Then, the bolt 79a passing through the nut holder 79 is screwed into a threaded hole (not shown) formed in the slide portion main body 32. As a result, the ball screw nut 72 is fixed in the large diameter hole 32c. In this way, the slide portion main body 32 has a function as a nut holder that holds the ball screw nut 72 accommodated in the large diameter hole 32c.

[0062] 6, when the ball screw 70 is fixed to the guide device 30, the small diameter portion 71c on the -Y side of the ball screw shaft 71 moves into the hole 11a of the rod 11. At this time, the outer periphery of the elastic member 110 comes into contact with the inner periphery of the hole 11a of the rod 11. As a result, the end of the ball screw shaft 71 on the -Y side is supported by this elastic member 110.

[0063] As shown in FIG. 3, the front housing 80 is fixed to the −Y side of the rail portion 60 by a bolt 81. The front housing 80 is formed by, for example, die casting. A through hole 80a for passing the rod 11 is formed in the front housing 80, and an oilless bearing 82 is disposed on the inner peripheral surface of the through hole 80a. The oilless bearing 82 supports the rod 11 so as to be movable in the Y-axis direction. As shown in FIG. 2, the front housing 80 is formed with protruding portions 83, 83 protruding in the +Y direction, and a screw hole 83a is formed on the upper surface (the surface on the +Z side) of each of the protruding portions 83, 83. A bolt 19 inserted through a through hole 18a formed in the cover 18 is fastened to the screw hole 83a.

[0064] As shown in FIG. 4, the bearing housing 90 is fixed to the +Y side of the rail portion 60 by bolts 91. The bearing housing 90 is formed by die casting, similar to the front housing 80. Furthermore, the bearing housing 90 has a through hole formed from the -Y side to the +Y side, with a large diameter hole 90a and a small diameter hole 90b continuing from the -Y side. The large diameter hole 90a accommodates a bearing 75. The bearing 75 is fitted into the large diameter hole 90a from the -Y side, and the bearing holder 77 is attached to the bearing housing 90 by bolts 78, whereby the bearing 75 is fixed in the large diameter hole 90a. The ball screw shaft 71 is rotatably supported by the bearing 75.

[0065] As shown in FIG. 2, a screw hole 90c is formed on the outer surface of the bearing housing 90 facing the +Z side. The screw hole 90c is used to fix the cover 18. A bolt 19 is inserted into the screw hole 90c through a through hole 18a formed in the cover 18. As shown in FIG. 4, the bearing housing 90 is formed with a protruding portion 95 protruding in the +Y direction. The protruding portion 95 is fitted into an opening 22a of the motor housing 22. At this time, the coupling 76 is connected to the output shaft 23 configured as a coupling. As a result, the rotational motion generated by the motor 21 is transmitted to the ball screw shaft 71. Then, a bolt 25 is screwed into a screw hole 22b formed in the motor housing 22. As a result, the upper surface (the surface on the +Z side) of the protruding portion 95 of the bearing housing 90 is pressed against the lower end of the bolt 25, so that the motor unit 20 is fixed to the bearing housing 90.

[0066] The operation of the actuator 10 configured as above will now be described.

[0067] First, when power is supplied to the motor 21 of the motor unit 20, the output shaft 23 of the motor 21 rotates in a predetermined direction. As a result, the ball screw shaft 71 connected to the output shaft 23 rotates together with the output shaft 23.

[0068] When the ball screw shaft 71 rotates, the ball screw nut 72 moves linearly, for example, in the -Y direction in accordance with the rotational motion of the ball screw shaft 71. When the ball screw nut 72 moves in the -Y direction, the slide part 31 that holds the ball screw nut 72 also moves in the -Y direction together with the ball screw nut 72.

[0069] At this time, ball 85 disposed in circulation path 43 provided on the -X side shown in Fig. 9 rolls clockwise in the figure within circulation path 43. On the other hand, ball 85 disposed in circulation path 43 provided on the +X side rolls counterclockwise in the figure within circulation path 43.

[0070] When the slide portion 31 of the guide device 30 moves in the -Y direction, the rod 11 fixed to the slide portion 31 via the connecting portion 50 also moves in the -Y direction together with the slide portion 31. This causes the tip fitting 12 attached to the tip of the rod 11 to move in the -Y direction.

[0071] With the above, the movement of the rod 11 and the end fitting 12 in the -Y direction is completed.

[0072] Next, when the output shaft 23 of the motor unit 20 rotates in a direction opposite to the predetermined direction, the ball screw shaft 71 connected to the output shaft 23 rotates together with the output shaft 23 .

[0073] When the ball screw shaft 71 rotates, the ball screw nut 72 moves linearly in the +Y direction in accordance with the rotational motion of the ball screw shaft 71. When the ball screw nut 72 moves in the +Y direction, the slide part 31 that holds the ball screw nut 72 also moves in the +Y direction together with the ball screw nut 72.

[0074] At this time, ball 85 disposed in circulation path 43 provided on the -X side shown in Fig. 9 rolls counterclockwise in the figure within circulation path 43. On the other hand, ball 85 disposed in circulation path 43 provided on the +X side rolls clockwise in the figure within circulation path 43.

[0075] When the slide portion 31 of the guide device 30 moves in the +Y direction, the rod 11 fixed to the slide portion 31 via the connecting portion 50 also moves in the +Y direction together with the slide portion 31. This causes the tip fitting 12 attached to the tip of the rod 11 to move in the +Y direction.

[0076] With the above, the movement of the rod 11 and the end fitting 12 in the +Y direction is completed, and the rod 11 and the end fitting 12 return to their initial positions.

[0077] In this way, if the actuator 10 continues to operate, the lubricating oil on the ball screw shaft 71 and the balls 85 will decrease. Therefore, it is necessary to supply the lubricating oil every time a predetermined operating time elapses. Next, the procedure for supplying the lubricating oil to the actuator 10 and the route through which the lubricating oil flows will be described.

[0078] First, as shown in Fig. 2, the cover 18 is removed from the actuator 10. This exposes the through-hole portion 36 formed in the slide portion main body 32. Next, a predetermined amount of lubricating oil is injected through the through-hole portion 36 using an oil gun (not shown).

[0079] The lubricating oil injected from the through hole portion 36 in this manner flows through the oil supply passage 2a as shown by the arrow Y1 in FIG. 8, and flows into the oil supply passage 2b. The lubricating oil that flows into the oil supply passage 2b flows through the oil supply passage 2b formed around the cylindrical portion 52 of the connecting portion 50 as shown by the arrows Y2 and Y3. When the lubricating oil flows to the connection point between the oil supply passage 2c and the oil supply passage 2g (the lower end of the oil supply passage 2b in FIG. 8), a part of the lubricating oil flows into the oil supply passage 2c as shown by the arrow Y4, and the remaining part flows into the through hole 50a through the oil supply passage 2g as shown by the arrow Y5. A part of the lubricating oil injected in this manner can be made to flow into the through hole 50a, and the lubricating oil can be supplied to the ball screw shaft 71 accommodated in the through hole 50a.

[0080] On the other hand, the lubricating oil that flows into the oil supply passage 2c flows through the oil supply passage 2d and flows into the oil supply passage 2e as shown by the arrow Y5 in the enlarged view of FIG. 9. Then, as shown by the arrows Y6 and Y7, the flow path of the lubricating oil is divided into two at the oil supply passage 2d and flows into the oil supply passages 2f, 2f. The lubricating oil that flows into the oil supply passage 2f on the -X side flows into the circulation passage 43 on the -X side. On the other hand, the lubricating oil that flows into the oil supply passage 2f on the +X side flows into the circulation passage 43 on the +X side. In this way, the lubricating oil can be made to flow into a pair of circulation passages 43, 43 formed in the slide portion 31. This allows the lubricating oil to be supplied to the balls 85 housed in the pair of circulation passages 43, 43.

[0081] After the injection of the lubricating oil is completed, the sliding portion 31 is moved back and forth along the Y axis manually or by driving the motor 21 to allow the lubricating oil to spread. Finally, the cover 18 shown in Fig. 2 is attached, and the operation of injecting the lubricating oil is completed.

[0082] As described above, in the actuator 10 according to this embodiment, the connecting part 50 is interposed between the slide portion main body 32 and the rod 11, and part of the oil supply passage to the ball screw shaft 71 and the balls 85 is provided in this connecting part 50. This reduces the number of oil supply passages provided in the slide portion main body 32, making it easier to ensure an oil supply passage even if the size of the slide portion main body 32 is reduced.

[0083] Furthermore, by forming an outer circumferential groove portion 53 that defines a part of the oil supply passage 2b around the outer circumferential surface of the cylindrical portion 52 of the connecting portion 50, the lubricating oil injected from the upper surface (surface facing the +Z side) of the sliding portion 31 can be guided to the lower portion (-Z side portion) of the sliding portion 31 by detouring around the ball screw shaft 71. This makes it easy to supply oil to the circulation passage 43 provided below the sliding portion 31.

[0084] In addition, oil supply passage 2c for supplying oil to balls 85 and oil supply passage 2g for supplying oil to ball screw shaft 71 are formed in positions facing each other with oil supply passage 2b in between. This allows the injected lubricating oil to be divided from oil supply passage 2b to oil supply passage 2c and oil supply passage 2g, and allows the ball screw shaft 71 and balls 85 to be lubricated by injecting lubricating oil once.

[0085] Furthermore, oil supply passages 2e, 2f, 2f are formed between the slide portion main body 32 and the return portion 40 attached to the end of the slide portion main body 32. These oil supply passages 2e, 2f, 2f are formed by recesses 46, 47, 47 provided in the abutment surface 41f of the return portion 40. This makes it possible to easily form oil supply passages to the pair of circulation passages 43 (balls 85). Furthermore, even if the number of oil supply passages provided in the slide portion main body 32 is reduced and the size of the slide portion main body 32 is reduced, it is easy to ensure oil supply passages to the pair of circulation passages 43.

[0086] Furthermore, the connecting part 50 is spigot-connected to the sliding part body 32 by fitting the cylindrical part 52, which is a convex part, into the medium-diameter hole 32a, which is a concave part, of the sliding part body 32. This allows the rod 11 connected to the connecting part 50 and the ball screw shaft 71 to be easily aligned, facilitating the assembly of the actuator 10.

[0087] The present invention is not limited to the above embodiment, and various modifications and applications are possible. In the above embodiment, the actuator 10 is used in a horizontally laid state, but the present invention is not limited to this, and the actuator 10 may be used in a vertically erected state.

[0088] In addition, a part of the circulation path 43 is formed by arranging steel members 35, 65 having groove portions 35a, 65a opposite each other on the slide portion main body 32 and the rail portion 60, but a part of the circulation path may also be formed by forming groove portions directly on the slide portion main body 32 and the rail portion 60.

[0089] Although the through-hole portion 36 has been described as being formed on the outer peripheral surface facing the +Z side of the sliding portion main body 32, it may be formed at another position. For example, it may be formed on the outer peripheral surface (side surface) on the +X side or the -X side.

[0090] Also, a resin or rubber lid may be provided on the through hole portion 36. Alternatively, a female thread may be formed in the through hole portion 36, and a bolt may be attached to the through hole portion 36. The lid or bolt is removed when refueling. This makes it possible to prevent the through hole portion 36 from becoming dirty with dirt, dust, and the like.

[0091] Further, the through hole portion 54 formed in the cylindrical portion 52 is provided at the lower end of the cylindrical portion 52 in FIG. 8, for example, but it may be provided at the upper end, or may be formed at the left or right end in a manner that passes through the X-axis. [Explanation of symbols]

[0092] 2a, 2b, 2c, 2d, 2e, 2f, 2g: Oil supply path 10: Actuator 11: Rod 11a: Hole 11b: Male threaded section 12: Tip fitting 18:Cover 18a, 34b, 50a, 66a, 80a: Through hole 19, 25, 56, 57, 78, 79a, 81, 91: Bolt 20: Motor unit 21: Motor 22: Motor housing 22a:Aperture 22b, 83a, 90c: Screw holes 23: Output shaft 24: Actuator cable 30: Guide device 31: Slide section 32: Slide body 32a: Medium diameter hole 32c, 90a: Large diameter hole 32b, 90b: Small diameter hole 33: Large cross section 34: Small cross section 34a, 41c, 46, 47, 62a: recess 34c,39:Screw holes 34d: Insertion hole 35,65:Steel parts 50:Connection part 35a, 65a: Groove 36, 54: Through hole section 37: Vertical hole 38:Horizontal drawing hole part 40: Return section 41: First return section 41a, 42c: Curved portion 41b, 42d, 55: Bolt insertion holes 41d: Bracket 41e: Curved outer wall 41f: Contact surface 42: Second return section 42a: Legs 42b: Horizontal member 42e: Inner wall of curve 43: Circulation route 43a, 43b: Straight passage section 43c, 43d: Curved passage 45: Protrusion 50b: Female thread 51: Block section 52: Cylindrical part 53: Outer circumferential groove 60: Rail section 61: Bass 62: Side wall 66: Lubricating oil pipe 70: Ball screw 71: Ball screw shaft 71a: Ball screw shaft body 71b, 71c: Small diameter part 72: Ball screw nut 75: Bearing 77: Bearing holder 76: Coupling 79: Nut holder 80: Front housing 82: Oil-less bearing 83,95:Protrusion 85: Ball 90: Bearing housing 110: Elastic member 112: Anti-slip material CL: Center line

Claims

1. a ball screw including a ball screw shaft rotated by a motor and a ball screw nut that moves linearly in accordance with the rotation of the ball screw shaft; a guide device including a slide portion that holds the ball screw nut, a rolling element that rolls in a circulation path, and a rail portion that supports the slide portion so as to be capable of linear motion via the rolling element; A working shaft that moves linearly together with the slide portion; a connecting portion that connects the slide portion and the working shaft, a through hole is formed in the slide portion, the through hole penetrating in a linear motion direction, which is a direction in which the slide portion linearly moves, and into which the ball screw nut and the fitting portion of the connecting portion are fixed, The connecting portion has an insertion hole through which the ball screw shaft is inserted, A female thread portion is formed on at least a part of an inner peripheral surface of the insertion hole to be screwed with a male thread portion formed on the working shaft, The fitting portion has a connection portion-side oil supply portion provided with an oil supply passage to the insertion hole and the circulation passage. Actuator.

2. the coupling portion-side oil supply portion has a first through-hole portion that penetrates from an outer periphery of the fitting portion to the insertion hole, The first through hole portion communicates with a second through hole portion that penetrates from an outer periphery of the slide portion to the through hole. The actuator according to claim 1 .

3. the coupling portion-side oil supply portion has an outer circumferential groove portion formed on an outer circumferential surface of the fitting portion, the slide portion has a second through hole portion penetrating from an outer periphery of the slide portion to the through hole, and a slide portion side oil supply portion provided with an oil supply path from the through hole to the circulation path, The outer circumferential groove portion communicates the second through hole portion and the slide portion side oil supply portion. The actuator according to claim 1 .

4. A return portion for turning the rolling element is attached to both ends of the slide portion, A part of the slide portion side oil supply portion is provided in the return portion. The actuator according to claim 3.

5. A part of the slide portion-side oil supply portion provided in the return portion is formed by a recess provided in a contact surface of the return portion that contacts the slide portion. The actuator according to claim 4.

6. The connecting portion is spigot-connected to the sliding portion by fitting the fitting portion into the through hole. The actuator according to claim 1 .

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