Ball screw shaft support structure and actuator

Abstract

To provide a ball screw support structure and an actuator capable of being reduced in size.SOLUTION: A ball screw shaft support structure comprises: a base; a ball screw shaft rotatably supported on the base; a ball screw nut movably screwed to the ball screw shaft; and a support member that is detachably installed on the ball screw shaft, is pressure-welded against the ball screw shaft from the base side by elastic means, and is biased against the elastic means and moved away from the ball screw shaft when the ball screw nut approaches, where a support shaft arranged parallel to the ball screw shaft is installed on the base, and the support member is supported by the support shaft so as to be swingable.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a ball screw shaft support structure and an actuator, and particularly to a structure devised to enable miniaturization.

Background Art

[0002] For example, Patent Document 1 discloses a configuration of a ball screw shaft support structure and an actuator. In the anti-vibration and stabilization device for a long lead screw described in Patent Document 1, a support base for preventing the deflection of the lead screw is provided below the lead screw. The support base is supported by support rods and is constantly biased toward the lead screw side by springs. A nut with a saddle attached is screwed onto the lead screw, and when the lead screw is rotated, the nut and the saddle are moved. A downward pressure roller is installed on the support base. When the saddle approaches the support base, the downward pressure roller abuts against a pressing plate provided on the saddle, and the support base is retracted downward against the spring.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the above conventional configuration has the following problems. That is, support rods and springs are installed below the lead screw, and furthermore, a space for the support rods to move up and down is secured, making it difficult to miniaturize.

[0005] The present invention has been made based on such points, and an object thereof is to provide a ball screw shaft support structure and an actuator that can be miniaturized.

Means for Solving the Problems

[0006] In order to solve the above problems, the ball screw shaft support structure according to claim 1 of the present invention includes a base, a ball screw shaft rotatably supported with respect to the base, a ball screw nut movably screwed onto the ball screw shaft, and a support member detachably installed on the ball screw shaft and pressed against the ball screw shaft from the base side by elastic means, and separated from the ball screw shaft against the elastic means when the ball screw nut approaches. The base is provided with a support shaft arranged in parallel with the ball screw shaft, and the support member is swingably supported by the support shaft. Further, the ball screw shaft support structure according to claim 2 is the ball screw shaft support structure according to claim 1, wherein the support member is biased toward the ball screw shaft side by a torsion spring installed as the elastic means on the support shaft side. Further, the ball screw shaft support structure according to claim 3 is the ball screw shaft support structure according to claim 1, wherein the support member is provided with a support portion that abuts against the ball screw shaft to support the ball screw shaft, and support member side inclined surfaces are provided on both axial sides of the ball screw shaft of the support portion of the support member. Further, the ball screw shaft support structure according to claim 4 is the ball screw shaft support structure according to claim 3, wherein a ball screw nut side roller is installed on the ball screw nut side, and the support member is separated from the ball screw shaft when the ball screw nut side roller rolls along the support member side inclined surface and the support portion. Furthermore, the ball screw shaft support structure according to claim 5 is the ball screw shaft support structure according to claim 4, wherein the support member side inclined surface is twisted so that the ball screw nut side roller abuts against the support member side inclined surface when the support member is swung. Furthermore, the ball screw shaft support structure according to claim 6 is the ball screw shaft support structure according to claim 3, wherein a buffer material for the inclined surface is installed on the support member side inclined surface. Furthermore, the actuator according to claim 7 is characterized in that one support member of the ball screw shaft support structure according to claim 1 is installed. Furthermore, the actuator according to claim 8 is characterized in that a plurality of support members of the ball screw shaft support structure according to claim 1 are installed.

Advantages of the Invention

[0007] As described above, according to the ball screw shaft support structure described in claim 1 of the present invention, a base, a ball screw shaft rotatably supported with respect to the base, a ball screw nut movably screwed to the ball screw shaft, and a support member detachably installed on the ball screw shaft and pressed against the ball screw shaft from the base side by elastic means and separated from the ball screw shaft against the elastic means when the ball screw nut approaches, and a support shaft arranged in parallel with the ball screw shaft is installed on the base, and the support member is swingably supported by the support shaft, so that no component is arranged in the space between the ball screw shaft and the base, and miniaturization can be achieved. Furthermore, according to the ball screw shaft support structure described in claim 2, in the ball screw shaft support structure described in claim 1, since the support member is biased toward the ball screw shaft side by a torsion spring installed as the elastic means on the support shaft side, there is no main part of the elastic means between the ball screw shaft and the base, and miniaturization can be achieved. Further, according to the ball screw shaft support structure described in claim 3, in the ball screw shaft support structure described in claim 1, the support member is provided with a support portion that abuts against the ball screw shaft to support the ball screw shaft, and support member side inclined surfaces are provided on both axial sides of the ball screw shaft of the support portion of the support member. Therefore, when the ball screw nut approaches the support member, the support member side inclined surface and the support portion are sequentially pressed to urge the support member, so that the ball screw shaft support structure can be operated smoothly. Further, according to the ball screw shaft support structure described in claim 4, in the ball screw shaft support structure described in claim 3, a ball screw nut side roller is installed on the ball screw nut side, and the ball screw nut side roller rolls along the support member side inclined surface and the support portion, so that the support member is separated from and abutted against the ball screw shaft. Therefore, the ball screw shaft support structure can be operated more smoothly. Further, according to the ball screw shaft support structure described in claim 5, in the ball screw shaft support structure described in claim 4, the support member side inclined surface is twisted so that the ball screw nut side roller abuts against the support member side inclined surface when the support member is swung. Therefore, the ball screw shaft support structure can be operated more smoothly. Further, according to the ball screw shaft support structure described in claim 6, in the ball screw shaft support structure described in claim 3, a buffer material for the inclined surface is installed on the support member side inclined surface, so that vibration and noise can be reduced. Further, according to the actuator described in claim 7, since one support member of the ball screw shaft support structure described in claim 1 is installed, the ball screw shaft can be miniaturized while preventing deflection with a simple configuration. Further, according to the actuator described in claim 8, since a plurality of support members of the ball screw shaft support structure described in claim 1 are installed, even a long ball screw shaft can be miniaturized while preventing deflection.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiments for Carrying out the Invention

[0009] Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 6. As shown in FIGS. 1 and 2, there is a base 3 having a substantially U-shaped cross-sectional shape. Guide rails 5, 5 are installed on the left and right inner side surfaces of the base 3. Guide grooves 7, 7 are respectively formed in the guide rails 5, 5.

[0010] Further, a ball screw shaft 9 is installed inside the base 3. As shown in FIG. 1, there is a bearing portion 11 on the front end side (lower right side in FIG. 1) of the base 3, and a bearing portion 13 on the rear end side (upper left side in FIG. 2) of the base 3. The ball screw shaft 9 is supported by these bearing portions 11, 13. A spiral groove 15 is formed on the ball screw shaft 9.

[0011] As shown in FIGS. 1 and 2, a slider 17 is installed on the base 3 so as to be movable in the front-rear direction (the direction from the upper left to the lower right in FIG. 1). End caps 19, 19 are installed at both ends in the front-rear direction (the direction from the upper left to the lower right in FIG. 1) on one side in the width direction of the slider 17 (the upper right side in FIG. 1). (The end cap on the rear end side is not shown.) Further, end caps 21, 21 are installed at both ends in the front-rear direction (the direction from the upper left to the lower right in FIG. 1) on the other side in the width direction of the slider 17 (the lower left side in FIG. 1). (The end cap on the rear end side is not shown.) Return paths (not shown) are formed in the end caps 19, 21. Non-load circulation paths (not shown) are formed on both sides in the width direction (the direction from the lower left to the upper right in FIG. 1) within the slider 17. Further, guide grooves (not shown) are formed on both side surfaces in the width direction (the direction from the lower left to the upper right in FIG. 1) of the slider 17.

[0012] Steel balls (not shown) roll and circulate in the space between one non-load circulation path (not shown) within the slider 17, the return path of one end cap 19, the return path of the other end cap 19, and the guide groove 7 of one guide rail 5 and one guide groove (not shown) of the slider 17. Also, steel balls (not shown) roll and circulate in the space between the other non-load circulation path (not shown) within the slider 17, the return path of one end cap 21, the return path of the other end cap 21, and the guide groove 7 of the other guide rail 5 and the other guide groove (not shown) of the slider 17. With such a configuration, the slider 17 is movable with respect to the base 3.

[0013] Also, as shown in FIG. 2, a ball screw nut 25 is fixed to the rear end side (upper left side in FIG. 1) inside the slider 17. The ball screw shaft 9 passes through the ball screw nut 25. A spiral groove (not shown) is formed on the inner peripheral surface of the ball screw nut 25. Further, a no-load circulation path (not shown) is formed inside the ball screw nut 25, and return paths (not shown) are formed on both sides in the front-rear direction (the direction from upper left to lower right in FIG. 1) of the no-load circulation path (not shown).

[0014] Steel balls (not shown) roll and circulate in the no-load circulation path (not shown) inside the ball screw nut 25, the return paths, and the space between the spiral groove of the ball screw nut 25 and the spiral groove 15 of the ball screw shaft 9. Also, as shown in FIG. 1, a motor 27 is installed on the rear end side (upper left side in FIG. 1) of the base 3. By this motor 27, the ball screw shaft 9 is rotated and driven. When the ball screw shaft 9 is rotated and driven, the ball screw nut 25 and thus the slider 17 are moved in the front-rear direction (the direction from upper left to lower right in FIG. 1).

[0015] Also, as shown in FIG. 2, a metal front roller 31 as a ball screw nut side roller is rotatably installed on one side in the width direction (lower side in FIG. 2) of the front end side (lower right side in FIG. 2) below the slider 17. Also, a metal rear roller 33 as a ball screw nut side roller is rotatably installed on one side in the width direction (upper side in FIG. 2) of the rear end side (upper left side in FIG. 2) below the slider 17.

[0016] Further, for example, as shown in FIG. 2, a support member mounting convex portion 35 is formed on the base 3. A ball screw shaft support structure 41 is fixed to the support member mounting convex portion 35. First, the ball screw shaft support structure 41 has a base 43 for a support member. The base 43 for the support member is a U-shaped member obtained by bending both ends of a plate-shaped member at right angles in the length direction (the direction from the upper left to the lower right in FIG. 3). Support member support through holes 45, 45 are formed on both ends of the base 43 for the support member in the length direction (the direction from the upper left to the lower right in FIG. 3), and a mounting through hole 47 is formed at the center of the base 43 for the support member in the length direction (the direction from the upper left to the lower right in FIG. 3). The base 43 for the support member is fixed to the base 3 by passing a bolt 49 through the mounting through hole 47 and screwing it into the support member mounting convex portion 35 of the base 3.

[0017] Bearings 55, 55 are press-fitted into the support member support through holes 45, 45, respectively. The bearing 55 is composed of a flange portion 57 disposed outside the base 43 for the support member and a protruding portion 59 inserted into the support member support through hole 45 and protruding inside the base 43 for the support member.

[0018] The ball screw shaft support structure 41 has a support member 61 supported swingably. The support member 61 has a support member body 63. The support member body 63 has a support portion 65 provided at the center in the front-rear direction (the direction from the upper left to the lower right in FIG. 3), a support member side inclined surface 67 provided on the front side (the lower right side in FIG. 3) of the support portion 65, and a support member side inclined surface 69 provided on the rear side (the upper left side in FIG. 3) of the support portion 65.

[0019] As shown in FIG. 4, a curved ball screw shaft bearing portion 71 that abuts along the shape of the ball screw shaft 9 is provided on the ball screw shaft 9 side (the upper right side in FIG. 4) of the support portion 65. Further, on the support member base 43 side (lower left side in FIG. 4) of the support portion 65, a slider contact portion 72 that contacts the bottom surface of the slider 17 is provided.

[0020] The support member side inclined surface 67 is disposed on the front side (right side in FIG. 4(a)) of the slider contact portion 72, is inclined so as to be lower toward the front side (right side in FIG. 4(a)), and has a twisted curved surface shape toward the direction of the swing (clockwise direction in FIG. 4(b)) in which the support portion 65 of the support member 61 descends. The support member side inclined surface 69 is also disposed on the rear side (left side in FIG. 4(a)) of the slider contact portion 72, is inclined so as to be lower toward the rear side (left side in FIG. 4(a)), and has a twisted curved surface shape toward the direction of the swing (clockwise direction in FIG. 4(b)) in which the support portion 65 of the support member 61 descends.

[0021] Also, a buffer material 68 for the inclined surface is installed on the support member side inclined surface 67, and a buffer material 70 for the inclined surface is installed on the support member side inclined surface 69. The buffer materials 68 and 70 for the inclined surface are, for example, made of low-rebound rubber. The front roller 31 and the rear roller 33 of the slider 17 are brought into contact with the support member side inclined surfaces 67 and 69 via the buffer materials 68 and 70 for the inclined surfaces. When the support member 61 is swung, due to the twisted shape of the support member side inclined surfaces 67 and 69, the front roller 31 and the rear roller 33 are rolled along the support member side inclined surfaces 67 and 69. That is, due to the twisted shape of the support member side inclined surfaces 67 and 69, the contact portions of the front roller 31 and the rear roller 33 with the support member side inclined surfaces 67 and 69 are configured to always be parallel to the rotation axes of the front roller 31 and the rear roller 33.

[0022] Further, on both sides of the support member 61 in the front-rear direction (the direction from the upper left to the lower right in FIG. 3), support portions 73, 73 protruding toward the base 43 side for the support member (the lower left side in FIG. 3) are provided respectively. A through hole 75 parallel to the ball screw shaft 9 is formed at the tip side (the lower left side in FIG. 3) of the support portion 73.

[0023] The support member 61 is swingably supported with respect to the base 43 for the support member by support shafts 77, 77 parallel to the ball screw shaft 9. The support shafts 77 are disposed through the bearing 55 and the through hole 75 of the support portion 73 of the support member 61. The support shaft 77 is press-fitted into the through hole 75 and fixed to the support member 61, but is rotatable with respect to the bearing 55.

[0024] Torsion springs 81, 81 as elastic means are respectively installed on the protruding portions 59, 59 of the bearings 55, 55. The protruding portion 59 of the bearing 55 penetrates the coil portion 82 of the torsion spring 81. One end side (the lower left side in FIG. 3) of the torsion spring 81 is engaged with an engaging portion 83 formed at both end sides in the length direction of the base 43 for the support member (the direction from the upper left to the lower right in FIG. 3), and the other end side (the upper right side in FIG. 3) abuts against the surface 85 on the base 3 side (the lower side in FIG. 3) of the support member 61. Thereby, the torsion springs 81, 81 bias the support member 61 toward the ball screw shaft 9.

[0025] As shown in FIG. 2(a) and FIG. 4, when the slider 17 is separated from the support member 61, the support member 61 is biased upward in FIG. 4(b) by the elastic force of the torsion springs 81, 81 and is swung in the counterclockwise direction in FIG. 4(b), and the ball screw shaft 9 is supported by the support member 61.

[0026] In the state shown in FIG. 2(a) and FIG. 4, the slider 17 is located on the rear side of the support member 61 (the upper left side in FIG. 2(a), the left side in FIG. 4(a)). When the slider 17 moves toward the support member 61 on the front side (the lower right side in FIG. 2(a), the right side in FIG. 4(a)), the front roller 31 of the slider 17 rolls on the buffer material 70 for the inclined surface of the support member side inclined surface 69. The support member 61 is biased downward in FIG. 4(b) against the elastic force of the torsion springs 81, 81 and is swung in the clockwise direction in FIG. 4(b) to be separated from the ball screw shaft 9. Further, when the slider 17 is moved forward (the lower right side in FIG. 2(a), the right side in FIG. 4(a)), after the front roller 31 rides on the slider contact portion 72 of the support portion 65, the bottom surface of the slider 17 comes into contact with the slider contact portion 72, resulting in the state shown in FIG. 2(b) and FIG. 5.

[0027] After that, when the slider 17 moves forward (the lower right side in FIG. 2(b), the right side in FIG. 5(a)) with the bottom surface of the slider 17 and the slider contact portion 72 in a sliding contact state, the rear roller 33 of the slider 17 rolls on the buffer material 68 for the inclined surface of the support member side inclined surface 67. The support member 61 is biased upward in FIG. 5(b) by the elastic force of the torsion springs 81, 81 and is swung in the counterclockwise direction in FIG. 5(b), and again, the ball screw shaft 9 is supported by the support member 61 as shown in FIG. 2(c) and FIG. 6.

[0028] When the slider 17 moves from the front side toward the rear support member 61, the rear roller 33 rolls on the buffer material 68 for the inclined surface of the support member side inclined surface 67, and the support member 61 is swung against the elastic force of the torsion springs 81, 81, and the support member 61 is separated from the ball screw shaft 9. When the slider 17 moves toward the rear side of the support portion 65, the bottom surface of the slider 17 comes into sliding contact with the slider contact portion 72 of the support member 61, and then the front roller 31 rolls on the buffer material 70 for the inclined surface of the support member side inclined surface 69, and the support member 61 is swung by the elastic force of the torsion springs 81, 81, and the ball screw shaft 9 is supported by the support member 61 again. With such a configuration, the support member 61 can be separated from and connected to the ball screw shaft 9.

[0029] Next, the operation according to the first embodiment will be described. When the ball screw shaft 9 is rotated and driven by the motor 27, the ball screw nut 25 and thus the slider 17 moves back and forth in the front-rear direction. In a state where the slider 17 is separated from the support member 61, as shown in FIGS. 2(a) and 4, the support member 61 is swung so as to be pressed and biased toward the ball screw shaft 9 by the elastic force of the torsion springs 81, 81, and the vicinity of the center of the ball screw shaft 9 is supported by the ball screw bearing portion 71 of the support portion 65, preventing the deflection of the ball screw shaft 9 and suppressing vibration and noise while moving the slider 17 at high speed.

[0030] In the state shown in FIG. 2(a) and FIG. 4, the slider 17 is located at the rear side of the support member 61 (the upper left side in FIG. 2(a), the left side in FIG. 4(a)). When the slider 17 moves toward the support member 61 at the front (the lower right side in FIG. 2(a), the right side in FIG. 4(a)), the front roller 31 of the slider 17 rolls on the inclined surface buffer material 70 of the support member side inclined surface 69. The support member 61 is biased downward in FIG. 4(b) against the elastic forces of the torsion springs 81, 81, and is swung in the clockwise direction in FIG. 4(b) and separated from the ball screw shaft 9. After the front roller 31 rides on the slider contact portion 72 of the support member 61, the bottom surface of the slider 17 comes into contact with the slider contact portion 72, resulting in the state shown in FIG. 2(b) and FIG. 5.

[0031] After that, when the slider 17 moves forward (the lower right side in FIG. 2(b), the right side in FIG. 5(a)) with the bottom surface of the slider 17 in sliding contact with the slider contact portion 72, the rear roller 33 of the slider 17 rolls on the inclined surface buffer material 68 of the support member side inclined surface 67. The support member 61 is biased upward in FIG. 5(b) by the elastic forces of the torsion springs 81, 81 and is swung in the counterclockwise direction in FIG. 5(b), and the ball screw shaft 9 is again supported by the support member 61 as shown in FIG. 2(c) and FIG. 6.

[0032] Further, when the slider 17 moves from the front side toward the rear support member 61, the rear roller 33 rolls on the inclined surface buffer material 68 of the support member side inclined surface 67, and the support member 61 is swung against the elastic forces of the torsion springs 81, 81, and the support member 61 is separated from the ball screw shaft 9. When the slider 17 moves toward the rear side of the support member 61, the bottom surface of the slider 17 comes into sliding contact with the slider contact portion 72 of the support member 61. Thereafter, the front roller 31 rolls on the inclined surface buffer material 70 of the support member side inclined surface 69, and the support member 61 is swung by the elastic forces of the torsion springs 81, 81, and the ball screw shaft 9 is supported by the support member 61 again.

[0033] Next, the effects of the first embodiment will be described. First, only the portion on the ball screw bearing portion 71 side of the support portion 65 of the support member 61 is arranged in the space between the ball screw shaft 9 and the base 3, and no other components are arranged. Therefore, the ball screw shaft support structure 41, and thus the actuator 1 can be miniaturized. Further, as the elastic means, since the torsion spring 81 is installed on the protruding portion 59 of the bearing 55 arranged on the outer peripheral side of the support shaft 77, the coil portion 82 of the torsion spring 81 is not arranged in the space between the ball screw shaft 9 and the base 3, and the ball screw shaft support structure 41, and thus the actuator 1 can be miniaturized.

[0034] When the slider 17 provided with the ball screw nut 25 approaches the support member 61, the slider 17 sequentially presses the support member side inclined surfaces 67, 69 and the support portion 65 to urge the support member 61 toward the base 3 side. Therefore, the ball screw shaft support structure 41 can be operated smoothly. Also, after the bottom surface of the slider 17 on which the ball screw nut 25 is installed rides on and slidably contacts the slider contact surface 72, when moving in a direction away from the slider contact surface 72, the slider 17 sequentially releases the pressing of the support portion 65 and the support member side inclined surfaces 67 and 69. Since the support member 61 is biased toward the ball screw shaft 9 side by the elastic force of the torsion springs 81 and 81, the ball screw shaft support structure 41 can be smoothly operated. The support member side inclined surface 67 is disposed on the front side (the right side in FIG. 4(a)) of the slider contact portion 72, is inclined so as to be lower toward the front side (the right side in FIG. 4(a)), and has a twisted curved surface shape toward the direction of the swing (clockwise direction in FIG. 4(b)) in which the support portion 65 of the support member 61 descends. The support member side inclined surface 69 is also disposed on the rear side (the left side in FIG. 4(a)) of the slider contact portion 72, is inclined so as to be lower toward the rear side (the left side in FIG. 4(a)), and has a twisted curved surface shape toward the direction of the swing (clockwise direction in FIG. 4(b)) in which the support portion 65 of the support member 61 descends. Therefore, when the support member 61 is swung, due to the twisted shapes of the support member side inclined surfaces 67 and 69, the front roller 31 and the rear roller 33 are rolled along the support member side inclined surfaces 67 and 69, and the ball screw shaft support structure 41 can be smoothly operated. Also, due to the twisted shapes of the support member side inclined surfaces 67 and 69, the portions where the front roller 31 and the rear roller 33 are in contact with the support member side inclined surfaces 67 and 69 are configured to always be parallel to the rotation axes of the front roller 31 and the rear roller 33. Therefore, the front roller 31 and the rear roller 33 can be stably rotated and smoothly operated.

[0035] Further, a buffer material 68 for the inclined surface is installed on the support member side inclined surface 67, and a buffer material 70 for the inclined surface is installed on the support member side inclined surface 69, so that vibration and noise can be reduced.

[0036] In addition, since one of the support members 61 is installed on the actuator 1, its structure is also simple.

[0037] Next, with reference to FIG. 7, a second embodiment of the present invention will be described. As shown in FIG. 7, the ball screw shaft support structure 201 according to this second embodiment has substantially the same configuration as the ball screw shaft support structure 41 in the actuator 1 according to the first embodiment described above. However, a coil spring 203 is installed as another elastic means below the support portion 65 of the support member 61 in FIG. 7(a).

[0038] Also in the case of this second embodiment, in addition to exhibiting the same operations and effects as those of the first embodiment described above, the support member 61 can be reliably returned by the coil spring 203. Note that components common to those in the first embodiment are denoted by the same reference numerals and their description is omitted.

[0039] Next, with reference to FIGS. 8 and 9, a third embodiment of the present invention will be described. As shown in FIGS. 8 and 9, the ball screw shaft support structure 301 has substantially the same configuration as the ball screw shaft support structure 41 in the actuator 1 according to the first embodiment described above and the ball screw shaft support structure 201 in the second embodiment described above. However, the torsion springs 81, 81 are removed, and only the coil spring 203 is installed as the elastic means.

[0040] Also in the case of this third embodiment, the same operations and effects as those of the first embodiment described above are exhibited. Note that components common to those in the first embodiment are denoted by the same reference numerals and their description is omitted.

[0041] Next, with reference to FIG. 10, a fourth embodiment of the present invention will be described. As shown in Fig. 10, the ball screw shaft support structure 401 has substantially the same configuration as the ball screw shaft support structure 41 in the actuator 1 according to the above-described first embodiment, but instead of the base 43 for one support member in the above-described first embodiment, base members 403, 403 for support members corresponding to the two support portions 73 of the support member 61 are provided. A through hole 405 for the support shaft is provided in the base member 403 for the support member.

[0042] Also, cylindrical bearings 407, 407 are press-fitted into the through holes 75, 75 of the support portions 73, 73, respectively, and the support member 61 is swingably supported by a support shaft 409 that passes through the bearings 407, 407 and the through holes 405, 405 for the support shaft of the base members 403, 403 for the support member. Also, instead of the torsion springs 81, 81 in the above-described first embodiment, one torsion spring 411 is provided. The torsion spring 411 is composed of two coil portions 413, 413, a support member biasing portion 415 between the coil portions 413, and base-side engaging portions 417 on both end sides. The torsion spring 411 is installed with the two coil portions 413, 413 passing through the support shaft 409 between the base members 403, 403 for the support member, the base-side engaging portions 417 are engaged with engaging recesses 419, 419 formed at the lower end sides of the base members 403, 403 for the support member, and the support member biasing portion 415 abuts against the lower side in Fig. 10 of the support portion 65 of the support member 61.

[0043] Also in the case of this fourth embodiment, the same operations and effects as those of the above-described first embodiment are achieved. Note that components common to those in the first embodiment are denoted by the same reference numerals and their description is omitted.

[0044] Next, a fifth embodiment of the present invention will be described with reference to Fig. 11. As shown in Fig. 11, the actuator 501 according to this fifth embodiment has substantially the same configuration as the actuator 1 according to the above-described first embodiment, but is provided with five ball screw shaft support structures 41.

[0045] Also in the case of this fifth embodiment, in addition to exhibiting the same operations and effects as those of the above-described first embodiment, it is possible to prevent the bending of the long ball screw shaft 9, suppress vibration and noise, and increase the speed of movement of the slider 17. Note that components common to those in the first embodiment are denoted by the same reference numerals and their description is omitted.

[0046] Note that the present invention is not limited to the first to fifth embodiments described above. First, various cases can be considered for the number of ball screw shaft support structures to be installed, depending on the length of the ball screw shaft. Also, various cases can be considered for the material of the cushioning material, such as felt, low-rebound rubber, other fabrics, rubber, resin, gel-like materials, porous materials such as sponge, and the like. Also, various cases can be considered for the material of the roller, such as metal, resin, rubber, oil-impregnated sintered material, and the like. It is also conceivable to install a member with good slidability on the lower surface side of the slider or on the side of the support portion that slides with the slider. It is also conceivable to install a cushioning material on the ball screw bearing portion. In addition, the illustrated configuration is merely an example.

Industrial Applicability

[0047] The present invention relates to a ball screw shaft support structure and an actuator, and particularly to an actuator devised to be miniaturized, and is suitable for, for example, industrial robots.

Explanation of Reference Numerals

[0048] 1 Actuator 3 Base 9 Ball screw shaft 17 Slider 25 Ball Screw Nut 31 Front Roller (Ball Screw Nut Side Roller) 33 Rear Roller (Ball Screw Nut Side Roller) 41 Ball Screw Shaft Support Structure 61 Support Member 65 Support Portion 67 Support Member Side Inclined Surface 68 Buffer Material for Inclined Surface 69 Support Member Side Inclined Surface 70 Buffer Material for Inclined Surface 71 Ball Screw Bearing Portion 72 Slider Contact Portion 73 Support Portion 77 Support Shaft 81 Twisting Spring (Elastic Means) 201 Ball Screw Shaft Support Structure 203 Coil Spring (Elastic Means) 301 Ball Screw Shaft Support Structure 401 Ball Screw Shaft Support Structure 409 Support Shaft 411 Twisting Spring (Elastic Means) 501 Actuator

Claims

1. With the base, a ball screw shaft rotatably supported on the base; and a ball screw nut movably screwed to the ball screw shaft; a support member that is detachably installed on the ball screw shaft, that is pressed against the ball screw shaft from the base side by an elastic means, and that is moved away from the ball screw shaft against the elastic means when the ball screw nut approaches; Equipped with A support shaft is provided on the base and is arranged parallel to the ball screw shaft. The support member is supported by the support shaft so as to be capable of swinging.

2. 2. The ball screw shaft support structure according to claim 1, a torsion spring provided as the elastic means on the support shaft side, the support member being biased toward the ball screw shaft side;

3. 2. The ball screw shaft support structure according to claim 1, The support member is provided with a support portion that abuts against the ball screw shaft to support the ball screw shaft, a support member-side inclined surface provided on both sides of the support portion of the support member in the axial direction of the ball screw shaft;

4. 4. The ball screw shaft support structure according to claim 3, A roller is installed on the ball screw nut side of the ball screw nut. a support portion that supports the ball screw shaft and the support member is moved toward and away from the ball screw shaft by the ball screw nut side rollers rolling along the support member side inclined surface and the support portion.

5. 5. The ball screw shaft support structure according to claim 4, A ball screw shaft support structure, characterized in that the support member side inclined surface is twisted so that the ball screw nut side roller abuts against the support member side inclined surface when the support member is swung.

6. 4. The ball screw shaft support structure according to claim 3, A ball screw shaft support structure characterized in that a cushioning material for an inclined surface is installed on the inclined surface on the support member side.

7. 2. An actuator comprising one support member having the ball screw shaft support structure according to claim 1.

8. 2. An actuator comprising a plurality of support members having the ball screw shaft support structure according to claim 1.

Images