Ball screw unit, slider unit, restriction unit, and method for manufacturing ball screw unit

Abstract

A ball screw unit attached to a screw shaft is provided with: a moving body capable of moving in the axial direction of the screw shaft in accordance with relative rotation with the screw shaft; and a restriction mechanism that restricts the relative rotation of the screw shaft and the moving body. The moving body includes an axial end surface in which an opening into which the screw shaft is inserted is formed. The restricting mechanism includes an attachment / detachment part that is detachably connected to an end surface of the moving body.

Description

Technical Field

[0001] The present invention relates to a ball screw unit, a slider unit, a limiting unit and a method for manufacturing the ball screw unit. Background Art

[0002] As a mechanism for converting rotational motion into linear motion, a ball screw is known. In order to suppress free fall when the screw shaft is arranged in a vertical direction, or inertial movement when the screw shaft is arranged in a horizontal direction, the ball screw is sometimes provided with a mechanism for generating a force (braking force) to resist the movement of the ball nut (for example, Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Utility Model Publication No. 59-144253 Summary of the invention

[0006] Problems to be solved by the invention

[0007] In the above-mentioned prior art, the protrusion of the piston is pressed against the thread groove of the screw shaft by using an air compressor, thereby generating a force that resists the movement of the ball nut. However, in the above-mentioned prior art, since the air compressor is used, the mechanism may be enlarged. In addition, the structure for mounting the piston on the ball nut is complicated, which may also affect the manufacturing cost.

[0008] The present invention provides a mechanism for generating a force resisting the movement of a ball nut with a simpler structure.

[0009] Means for solving problems

[0010] According to the present invention, there is provided a ball screw unit, which is mounted on a screw shaft and is characterized in that the ball screw unit comprises:

[0011] a moving body capable of moving in the axial direction of the screw shaft as the moving body rotates relative to the screw shaft; and

[0012] a limiting mechanism for limiting the relative rotation between the screw shaft and the moving body,

[0013] The moving body includes an axial end surface having an opening for inserting the screw shaft.

[0014] The restriction mechanism includes a detachable portion detachably connected to the end surface of the movable body.

[0015] Effects of the Invention

[0016] According to the present invention, it is possible to provide a mechanism that generates a force resisting the movement of the ball nut with a simpler structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a perspective view of the appearance of a ball screw unit according to one embodiment.

[0018] Figure 2 This is an exploded perspective view of the ball screw unit.

[0019] Figure 3 This is a cross-sectional view for explaining the internal structure of the ball screw unit.

[0020] Figure 4 yes Figure 3 A partial enlarged view of .

[0021] Figure 5A is a side view of the housing.

[0022] Figure 5B yes Figure 5A View in direction B.

[0023] Figure 5C yes Figure 5A View in the C direction.

[0024] Figure 5D yes Figure 5B VV line cross-sectional view.

[0025] Figure 6 It is a figure for demonstrating the manufacturing process of a ball screw unit.

[0026] Figure 7 It is a perspective view schematically showing the structure of the slider unit.

[0027] Figure 8 It is a diagram for explaining the fastening structure of the ball nut, the restriction mechanism, and the slider.

[0028] Fig. 9 This is an exploded perspective view of a ball screw unit according to one embodiment.

[0029] Fig.10 It is used to illustrate Fig. 9 A cross-sectional view of the internal structure of a ball screw unit.

[0030] Fig.11A It is a figure for demonstrating the manufacturing process of a ball screw unit.

[0031] Fig. 11B It is a figure for demonstrating the manufacturing process of a ball screw unit.

[0032] Fig.12It is a diagram for explaining the relationship between the groove of the nut and the through hole of the housing. DETAILED DESCRIPTION

[0033] Hereinafter, the embodiments are described in detail with reference to the accompanying drawings. It should be noted that the following embodiments do not limit the invention involved in the scope of protection of the claims. In addition, all combinations of features described in the embodiments are not necessary for the invention. Two or more of the multiple features described in the embodiments may also be combined arbitrarily. In addition, the same or similar structures are marked with the same figure marks, and repeated descriptions are omitted.

[0034] <1. First Embodiment>

[0035] <1.1. Ball screw unit>

[0036] <1.1.1. Summary>

[0037] Figure 1 It is an external perspective view of the ball screw unit 1 according to one embodiment. Figure 2 It is an exploded perspective view of the ball screw unit 1 . Figure 3 1 is a cross-sectional view for explaining the internal structure of the ball screw unit 1. The ball screw unit 1 is a unit that is attached to the screw shaft 101 and is movable in the axial direction of the screw shaft 101. The ball screw unit 1 includes a ball nut 10 and a restriction mechanism 20.

[0038] <1.1.2. Ball nut>

[0039] The ball nut 10 is an example of a movable body that can move in the axial direction (hereinafter sometimes referred to as the axial direction) of the screw shaft 101 as it rotates relative to the screw shaft 101. As the ball nut 10, a known mechanism can be appropriately adopted. In the present embodiment, the ball nut 10 includes a main body 11 and a flange 12. The main body 11 is embedded in the screw shaft 101 via balls not shown in the figure. Thus, the rotational motion of the screw shaft 101 is converted into the linear motion of the ball nut 10. In addition, the main body 11 forms a circulation path for the balls not shown in the figure.

[0040] The flange 12 is formed to extend from the body 11 to the outside in the radial direction (hereinafter sometimes referred to as the radial direction) of the screw shaft 101. A plurality of bolt holes 121 are formed in the flange 12 and penetrate in the axial direction. In a general ball nut 10, a moving object (such as a slider 203 described later) can be mounted on the ball nut 10 using the bolt holes 121.

[0041] <1.1.3. Restricted institutions>

[0042] The limiting mechanism 20 limits the relative rotation between the screw shaft 101 and the ball nut 10. In other words, the limiting mechanism 20 generates a force (braking force) that resists the movement of the ball nut 10 relative to the screw shaft 101. In the present embodiment, the limiting mechanism 20 is configured to be able to be loaded and unloaded relative to the ball nut 10. As described in detail later, the limiting mechanism 20 can be loaded and unloaded relative to the ball nut 10 in which a storage space for accommodating the limiting mechanism 20 is not formed. The limiting mechanism 20 includes a housing 23, a nut 21, a coil spring 22, and a screw-fitting component 24.

[0043] It should be noted that, in the present embodiment, the state in which the relative rotation is limited by the limiting mechanism 20 may also be a state in which the torque required for the relative rotation of the screw shaft 101 and the ball nut 10 becomes larger than that in the case where the limiting mechanism 20 is not provided. That is, as long as the braking force for limiting the relative rotation of the screw shaft 101 and the ball nut 10 is generated by the limiting mechanism 20, the degree of limitation (the magnitude of the braking force) by the limiting mechanism 20 can be appropriately set. For example, in the case of using the ball screw unit 1 in a manner in which the axial direction of the screw shaft 101 becomes a horizontal direction, the relative rotation may also be limited to a degree that can suppress inertial movement when the moving body including the ball nut 10 stops. Alternatively, in the case of using the ball screw unit 1 in a manner in which the axial direction of the screw shaft 101 becomes a vertical direction, the relative rotation may also be limited to a degree that can suppress the falling of the dead weight when the moving body including the ball nut 10 stops. In addition, when a torque greater than the braking force generated by the limiting mechanism 20 is applied to the screw shaft 101, the screw shaft 101 rotates and the ball nut 10 moves relative to the screw shaft 101.

[0044] In addition, in the present embodiment, the limiting mechanism 20 can be attached and detached with respect to the ball nut 10 as an example of a moving body. However, the limiting mechanism 20 can also be attached and detached with respect to other moving bodies that are transported together with the ball nut 10. For example, in the case where the ball screw unit 1 is applied to the slider unit U1 described later, the limiting mechanism 20 can also be attached and detached with respect to the slider 203 instead of the ball nut 10. That is, the limiting mechanism 20 only needs to be attached and detached with respect to the moving body constituted by the ball nut 10.

[0045] (Nut and coil spring)

[0046] The nut 21 is an example of a limiting component that limits the relative rotation of the screw shaft 101 and the ball nut 10 by using the friction force (braking force) generated between the nut 21 and the screw shaft 101. The nut 21 is a cylindrical component embedded in the screw shaft 101, including a groove 211 formed on its outer peripheral surface and a threaded tooth 212 formed on its inner peripheral surface. The groove 211 is formed to extend in the axial direction. As described in detail later, the relative rotation of the nut 21 and the housing 23 is limited by inserting the front end of the screw-fitting component 24 into the groove 211.

[0047] In addition, in the present embodiment, the nut 21 is configured to include a raw material having self-lubricating properties. For example, the nut 21 is formed using a raw material impregnated with lubricating oil. In one embodiment, the nut 21 may include a resin material. By configuring the nut 21 to include a raw material having self-lubricating properties, wear of the nut 21 and the screw shaft 101 can be suppressed. In addition, by moving the nut 21 axially relative to the screw shaft 101, a lubricant is applied to the screw shaft 101. Therefore, there is no need to provide a component for supplying a lubricant such as grease to a ball not shown in the figure, and therefore the number of components can be reduced.

[0048] The coil spring 22 is an example of an urging member that urges the nut 21 relative to the screw shaft 101 so as to generate friction force between the nut 21 and the screw shaft 101. As the urging member, other members such as a leaf spring and a disc spring described later may be used.

[0049] Here, Figure 4 yes Figure 3 The partially enlarged view is a diagram for explaining that the limiting mechanism 20 limits the relative rotation of the screw shaft 101 and the ball nut 10. By applying a force to the nut 21 in one axial direction by the coil spring 22, the part of the axial side of the thread teeth 212 of the nut 21 in one axial direction abuts against the part of the axial side of the thread teeth 101a of the screw shaft 101 in the other axial direction. As a result, as a resistance to the rotation of the screw shaft 101, a certain friction force corresponding to the force of the coil spring 22 is generated between the nut 21 and the screw shaft 101. The limiting mechanism 20 allows the relative rotation of the screw shaft 101 with respect to the nut 21, for example, when a torque exceeding the above-mentioned friction force is transmitted to the screw shaft 101 from the drive source 202 described later, and limits the relative rotation of the screw shaft 101 with respect to the nut 21 when a torque lower than the friction force is transmitted to the screw shaft 101.

[0050] In the present embodiment, the relative rotation between the ball nut 10 and the screw shaft 101 is limited by using the nut 21 and the coil spring 22. Therefore, compared with the case where their relative rotation is limited by an actuator such as an electromagnetic brake or an air compressor, the structure can be simplified and the device can be miniaturized. In addition, in the present embodiment, since their relative rotation is limited by a mechanical mechanism, energy consumption can be reduced compared with the case where the actuator is driven to limit the relative rotation. Furthermore, even when the power supply is lost due to a power outage in the facility, the relative rotation restriction state can be maintained.

[0051] Furthermore, the friction between the nut 21 and the screw shaft 101 can be adjusted by adjusting the magnitude of the force (biasing force) applied by the coil spring 22 to the nut 21. That is, the magnitude of the braking force generated by the restriction mechanism 20 can be adjusted by adjusting the magnitude of the biasing force.

[0052] (shell)

[0053] and Figure 1 to Figure 3 Refer to Figure 5A to Figure 5D . Figure 5A is a side view of the housing 23. Figure 5B yes Figure 5A View in direction B. Figure 5C yes Figure 5A View in the C direction. Figure 5D yes Figure 5B VV line cross-sectional view.

[0054] The housing 23 accommodates the nut 21 and the coil spring 22. The housing 23 includes a plurality of bolt holes 231 that penetrate in the axial direction. The bolt hole 231 is an example of a detachable portion that is detachably connected to the ball nut 10. The ball nut 10 and the limiting mechanism 20 are connected by inserting and fastening the bolt 30, which is an example of a fastening member, into the bolt hole 121 of the ball nut 10 and the bolt hole 231 of the housing 23. That is, the limiting mechanism 20 can be attached and detached relative to the ball nut 10 by bolt fastening in a state where the nut 21 and the coil spring 22 are accommodated. It should be noted that the fastening method based on the bolt 30 can be appropriately changed. For example, the ball nut 10 and the housing 23 of the limiting mechanism 20 can be fastened by the bolt 30 and a nut not shown in the figure, or a groove that is screwed with the bolt 30 can be formed in either the bolt hole 121 or the bolt hole 231.

[0055] In addition, in the present embodiment, the limiting mechanism 20 is connected to the end face 13 of the ball nut 10 so as to be detachable. Here, the end face 13 is an axial end face of the ball nut 10 in which an opening is formed for inserting the screw shaft 101. In this way, since the limiting mechanism 20 can be attached and detached relative to the end face 13 of the ball nut 10 as an example of a moving body, it is not necessary to form a space for accommodating the components of the limiting mechanism 20 on the side of the ball nut 10. Therefore, the structure of the ball nut 10 can be simplified.

[0056] In addition, the housing 23 includes an end 233 and an end 234 in the axial direction. The end 233 is installed relative to the ball nut 10. In detail, the end 233 contacts the end face 13 of the ball nut 10 when the ball nut 10 is connected to the limiting mechanism 20. On the other hand, the end 234 is an end that is farther away from the ball nut 10 in the axial direction than the end 233. In the present embodiment, a recess 234a is formed at the end 234, and the recess 234a is recessed in such a manner that the head 30a of the bolt 30 passing through the bolt hole 231 does not protrude axially relative to the end 234. As a result, it is possible to suppress the protrusion of the head 30a of the bolt 30, etc., and therefore, the ball screw unit 1 can be miniaturized in the axial direction. Figure 5A The position of the head 30 a when the bolt 30 is inserted into the bolt hole 231 is shown.

[0057] In the present embodiment, the bolt hole 231 is arranged so as to overlap with the bolt hole 121 of the ball nut 10 when viewed in the axial direction of the screw shaft 101 when the screw shaft 101 is passed through the inner side of the housing 23. Therefore, the limiting mechanism 20 and the ball nut 10 can be connected using the bolt hole 121, which is usually provided in the ball nut 10 for mounting a component that becomes a moving object. Therefore, the ball nut 10 does not require a dedicated structure for mounting the limiting mechanism 20. That is, the limiting mechanism 20 can be mounted and dismounted relative to the so-called general ball nut 10.

[0058] The internal structure of the housing 23 is described in detail. The housing 23 includes a wall portion 232, which forms a receiving space 25 for receiving the nut 21 and the coil spring 22. The wall portion 232 includes a peripheral wall portion 2321 that forms a side of the receiving space 25 and a bottom wall portion 2322 that forms an end portion 251 of the receiving space 25 in the axial direction. The bottom wall portion 2322 is formed to extend from the peripheral wall portion 2321 to the inner side in the radial direction of the screw shaft 101. It should be noted that in the axial direction, the other end of the receiving space 25 on the side opposite to the one end portion 251 is divided by the end face 13 of the ball nut 10 when the limiting mechanism 20 is connected to the ball nut 10.

[0059] In the present embodiment, the coil spring 22 is disposed between the nut 21 and the bottom wall portion 2322. With such an arrangement, the bottom wall portion 2322 functions as a support surface for the coil spring 22. Therefore, it is not necessary to form a support surface for the coil spring 22 on the ball nut 10 side, and thus the structure of the ball nut 10 can be simplified.

[0060] In addition, in the present embodiment, the accommodation space 25 includes a nut accommodation portion 25a for accommodating the nut 21 and a coil spring accommodation portion 25b for accommodating the coil spring 22. Furthermore, the peripheral wall portion 2321 includes a nut side peripheral wall portion 2321a forming the side of the nut accommodation portion 25a and a spring side peripheral wall portion 2321b forming the side of the coil spring accommodation portion 25b. The nut accommodation portion 25a is a space larger than the coil spring accommodation portion 25b in the radial direction. Furthermore, the nut side peripheral wall portion 2321a and the spring side peripheral wall portion 2321b are connected by a connecting wall portion 2323 extending in the radial direction.

[0061] In the present embodiment, the nut 21 and the connecting wall portion 2323 overlap when viewed in the axial direction of the screw shaft 101. Figure 5C In the figure, the position of the outer peripheral surface 213 of the nut 21 when the nut 21 is accommodated in the nut housing portion 25a is indicated by a dotted line. In the radial direction of the screw shaft 101, the nut 21 is set to the following size: the outer peripheral surface 213 of the nut 21 is located at a position closer to the inside than the nut side peripheral wall portion 2321a and is located outside the spring side peripheral wall portion 2321b. Thus, in the direction close to the end portion 234, the installation position of the nut 21 to the screw shaft 101 is determined by the connecting wall portion 2323. That is, in the axial direction of the screw shaft 101, the minimum distance between the nut 21 and the bottom wall portion 2322 is specified, so that the maximum compression amount of the coil spring 22 can be set to a fixed value.

[0062] In addition, in the present embodiment, by adjusting the position of the nut 21 relative to the nut housing portion 25a in the axial direction, the compression amount of the coil spring 22 can be adjusted, and as a result, the magnitude of the braking force generated by the limiting mechanism 20 can be adjusted. In detail, in the present embodiment, since the nut housing portion 25a is larger than the nut 21 in the axial direction, the axial configuration of the nut 21 in the nut housing portion 25a has a degree of freedom. On the other hand, the nut 21 is screwed with the screw shaft 101, and the rotation is restricted by the screwing component 24, so the axial movement is restricted in the nut housing portion 25a. Specifically, when the nut 21 and the screw shaft 101 do not rotate relative to each other, the axial movement of the nut 21 is restricted within the range where the thread teeth 212 of the nut 21 and the thread teeth 101a of the screw shaft 101 do not interfere (in other words, the range of the backlash amount of the screwed nut 21 and the screw shaft 101). Therefore, by positioning the nut 21 at a desired position in the axial direction relative to the nut housing portion 25a during assembly, the compression amount of the coil spring 22 can be adjusted. Specifically, the closer the nut 21 is to the coil spring housing portion 25b in the nut housing portion 25a, the greater the compression of the coil spring 22 can be; and the closer the nut 21 is to the end face 13 of the ball nut 10 in the nut housing portion 25a, the less the compression of the coil spring 22 can be.

[0063] Furthermore, in the present embodiment, the entire nut 21 is accommodated in the housing 23 in the axial direction. Thus, it is not necessary to provide a structure (counterbore, etc.) for accommodating the components of the limiting mechanism 20 in the ball nut 10. Therefore, since it is not necessary to provide a structure for accommodating the limiting mechanism 20 in the ball nut 10, the structure of the ball nut 10 can be simplified. In addition, since it is not necessary to provide a structure for accommodating the limiting mechanism 20 in the ball nut 10, it is possible to easily install the limiting mechanism 20 without performing special processing on the general-purpose ball nut 10.

[0064] Furthermore, a through hole 235 penetrating in the radial direction of the screw shaft 101 is formed in the housing 23. A thread groove with which the screw member 24 is screwed is formed on the inner surface of the through hole 235.

[0065] (Screw-on parts)

[0066] The screw-in component 24 restricts the nut 21 from rotating relative to the housing 23. The screw-in component 24 is screwed with the through hole 235. For example, the screw-in component 24 may be a set screw or the like. In the present embodiment, by inserting the front end of the screw-in component 24 into the groove 211 while the screw-in component 24 is screwed with the through hole 235, the nut 21 can move in the axial direction but cannot rotate relative to the housing 23.

[0067] In detail, since the groove 211 is formed along the axial direction, when the nut 21 and the housing 23 move relative to each other in the axial direction, the front end of the screw component 24 will not interfere with the nut 21. Therefore, the nut 21 and the housing 23 can move relative to each other in the axial direction. However, in the relationship between the nut 21 and the screw shaft 101, without the relative rotation of the nut 21 and the screw shaft 101, as described above, the relative movement in the axial direction is limited to the range of the tooth gap between the screwed nut 21 and the screw shaft 101. Therefore, as a result, the nut 21 can also move relative to the housing 23 in the axial direction within the range of the tooth gap between the screwed nut 21 and the screw shaft 101.

[0068] On the other hand, when the nut 21 is to rotate relative to the housing 23, the front end of the screw-in component 24 abuts against the surface extending in the axial direction and radial direction of the groove 211. As a result, the nut 21 cannot rotate relative to the housing 23. In this way, in the present embodiment, the rotation restriction of the nut 21 can be achieved with a simple structure using the screw-in component 24. It should be noted that, in the present embodiment, the screw-in component 24 prevents the nut 21 and the housing 23 from rotating relative to each other, but their relative rotation can also be restricted by other components such as pins. In this case, the pin can also be pressed into the through hole 235.

[0069] As described above, according to the present embodiment, a mechanism for generating a force (braking force) resisting the movement of the ball nut 10 can be provided with a simple structure. In addition, since it can be easily mounted on a common ball nut 10, it is easy to use the restriction mechanism 20 as a common component. In addition, by only using the restriction mechanism 20 that is separate from the moving body such as the ball nut 10, it is possible to adjust and mount the braking force (acting force) regardless of the moving body.

[0070] <1.2. Method for manufacturing ball screw unit>

[0071] Next, a method for manufacturing the ball screw unit 1 will be described. Figure 6 The diagrams are for explaining the manufacturing process of the ball screw unit 1 .

[0072] In S1, the ball nut 10 as an example of a moving body is assembled to the screw shaft 101. In other words, this step is a step of preparing a ball screw including the ball nut and the screw shaft.

[0073] In S2 , the nut 21 is fitted into the screw shaft 101 . In S3 , the housing 23 accommodating the coil spring 22 as an example of the urging member is inserted into the screw shaft 101 , so that the nut 21 is urged relative to the screw shaft 101 by the coil spring 22 .

[0074] In S4, the nut 21 is restricted to be non-rotatable relative to the housing 23 by the screwing member 24. That is, the screwing member 24 is screwed through the through hole 235, and the front end of the screwing member 24 is inserted into the groove 211 of the nut 21, thereby restricting the relative rotation of the nut 21 and the housing 23.

[0075] In S5 , the housing 23 is mounted on the ball nut 10 . That is, the ball nut 10 and the housing 23 are fastened together by the bolts 30 .

[0076] As described above, in the present embodiment, the restriction mechanism 20 can be easily mounted on the ball nut 10 .

[0077] <1.3. Slider unit>

[0078] A slider unit U1 as an application example of the ball screw unit 1 will be described. Figure 7 It is a perspective view schematically showing the structure of the slider unit U1.

[0079] The slider unit U1 includes a ball screw unit 1, a screw shaft 101, a support 201, a drive source 202, a slider 203, and a guide rail 204. The slider unit U1 can be used in a manner that the slider 203 moves in a horizontal direction or in a vertical direction.

[0080] The screw shaft 101 is rotatably supported by a support portion 201. The support portion 201 includes, for example, a bearing (not shown). The screw shaft 101 rotatably supported by the support portion 201 is rotated by a drive source 202. The drive source 202 is, for example, an electric motor.

[0081] In the present embodiment, the ball nut 10 and the slider 203 included in the ball screw unit 1 constitute a moving body. That is, when the screw shaft 101 is rotated by the driving source 202, the ball screw unit 1 and the ball nut 10 become one, and move relative to the screw shaft 101 in the axial direction. The slider 203 is a component that becomes the moving object of the ball screw unit 1. For example, a workbench or the like for positioning and transporting components can be installed on the slider 203.

[0082] The guide rail 204 is a component that guides the linear motion of the slider 203. The slider 203 is formed with a groove 2031 that receives the guide rail 204.

[0083] Figure 8 1 is a diagram for explaining the fastening structure of the ball nut 10, the limiting mechanism 20, and the slider 203. Here, in the present embodiment, the slider 203, the ball nut 10, and the housing 23 of the limiting mechanism 20 are fastened by a common bolt 31. In the so-called universal ball nut 10, a bolt hole 121 for mounting a member that becomes a moving object, such as the slider 203, is provided in its flange 12 portion. Therefore, in the case where the limiting mechanism 20 is not provided, by passing the bolt 31 through the bolt hole 121 and the bolt hole of the slider 203, they can be fastened. In the present embodiment, by using the bolt hole 121 to also mount the limiting mechanism 20 on the ball nut 10, the limiting mechanism 20 can be mounted without increasing the number of bolts compared to the case where the limiting mechanism 20 is not provided. Furthermore, since the slider 203 , the ball nut 10 , and the restriction mechanism 20 are fastened by the common bolt 31 , the bolt hole 231 of the restriction mechanism 20 is arranged to overlap with the bolt hole 121 of the ball nut 10 when viewed in the axial direction when assembled to the screw shaft 101 .

[0084] <2. Second Embodiment>

[0085] <2.1. Ball screw unit>

[0086] Fig. 9 : is an exploded perspective view of a ball screw unit 501 according to an embodiment. Fig.10 It is used to illustrate Fig. 9 2 is a cross-sectional view of the internal structure of the ball screw unit 501. Hereinafter, the same components as those of the ball screw unit 1 according to the first embodiment are denoted by the same reference numerals and their description is omitted.

[0087] The ball screw unit 501 includes a ball nut 10 and a restriction mechanism 520. The restriction mechanism 520 includes a nut 521, a disc spring 522, and a housing 523.

[0088] The nut 521 is an example of a limiting component that limits the relative rotation of the screw shaft 101 and the ball nut 10 by utilizing the friction force (braking force) generated between the nut 521 and the screw shaft 101. The nut 521 includes a contact portion 5211, a boss portion 5212, a groove 5213, and a thread 212 formed on the inner circumferential surface of the contact portion 5211 and the boss portion 5212.

[0089] The contact portion 5211 is the portion in contact with the disc spring 522. In other words, the contact portion 5211 is the portion that receives the force from the disc spring 522. A plurality of grooves 5213 extending along the axial direction of the screw shaft 101 are formed on the outer peripheral surface of the contact portion 5211. The plurality of grooves 5213 are arranged in an circumferential direction of the screw shaft 101. Details will be described later (refer to Fig.12 ), the number and configuration of multiple slots 5213 can be changed appropriately.

[0090] The boss portion 5212 is a portion extending in the axial direction from the contact portion 5211. The diameter of the boss portion 5212 is smaller than the diameter of the contact portion 5211. More specifically, the diameter of the boss portion 5212 is smaller than the diameter of the opening formed in the bottom wall portion 5232d of the housing 523.

[0091] The disc spring 522 is an example of a force-applying component that applies force to the nut 521 relative to the screw shaft 101 in a manner that generates a friction force between the nut 521 and the screw shaft 101. For example, the disc spring 522 is formed of a resin material, a metal material, etc. Three disc springs 522 are shown here, but the number of disc springs 522 used can be appropriately changed.

[0092] The housing 523 accommodates the nut 521 and the disc spring 522. The housing 523 includes a bolt hole 5231 and a wall portion 5232 that forms a space for accommodating the nut 521 and the disc spring 522.

[0093] The bolt hole 5231 is an example of a detachable portion detachably connected to the ball nut 10. The ball nut 10 and the limiting mechanism 520 are connected by inserting and fastening the bolt 30 as an example of a fastening member into the bolt hole 121 of the ball nut 10 and the bolt hole 5231 of the housing 23. Fig. 9In the example, the bolt holes 5231 are provided in such a manner that the distance between two bolt holes arranged diagonally among the four bolt holes 121 provided in the general ball nut 10 is consistent with the distance between the two bolt holes 5231 provided in the housing 523. It should be noted that three or more bolt holes 121 (for example, four corresponding to the four bolt holes 121 of the ball nut 10) may be provided in the housing 523. Alternatively, the number and positions of the bolt holes 121 of the ball nut 10 are not limited to the example shown in the figure.

[0094] The wall portion 5232 includes: a side peripheral wall portion 5232a forming the side of the accommodation space of the nut 521 and the disc spring 522; and a bottom wall portion 5232d forming the end portion 251 of the accommodation space 25 in the axial direction. The bottom wall portion 5232d is formed to extend from the side peripheral wall portion 5232a to the inner side in the radial direction of the screw shaft 101. It should be noted that in the axial direction, the other end of the accommodation space 25 on the side opposite to the side where the bottom wall portion 5232d is provided is divided by the end face 13 of the ball nut 10 when the limiting mechanism 520 is connected to the ball nut 10.

[0095] The side circumferential wall portion 5232a includes a nut side circumferential wall portion 5232b forming the side of the portion of the accommodating space 25 that accommodates the nut 521 and a spring side circumferential wall portion 5232c forming the side of the portion of the accommodating space 25 that accommodates the disc spring 522. The inner circumferential surface of the spring side circumferential wall portion 5232c is larger than the inner circumferential surface of the nut side circumferential wall portion 5232b in the radial direction. The nut side circumferential wall portion 5232b and the spring side circumferential wall portion 5232c are connected by a connecting wall portion 5232e extending in the radial direction. The connecting wall portion 5232e overlaps with the disc spring 522 when viewed in the axial direction. In other words, the connecting wall portion 5232e overlaps with the disc spring 522 in the radial direction. Thus, the disc spring 522 can be clamped by the end surface of the ball nut 10 and the connecting wall portion 5232e.

[0096] In addition, the nut side peripheral wall portion 5232b is arranged at a position closer to the bottom wall portion 5232d than the spring side peripheral wall portion 5232c in the axial direction. Therefore, when the nut 521 and the disc spring 522 are accommodated in the housing 523, the nut 521 is arranged between the disc spring 522 and the bottom wall portion 5232d.

[0097] In this embodiment, through holes 5235 penetrating in the radial direction of the screw shaft 101 are formed in the housing 523 in a row in the circumferential direction. A thread groove that is screwed with the screw member 24 is formed on the inner surface of the through hole 5235.

[0098] It should be noted that, in this embodiment, the disc spring 522 has a length L1 (i.e., a natural length, see Fig.12) is longer than the axial length L2 of the spring side peripheral wall portion 5232c. In addition, the axial length of the nut 521, which is a combination of the contact portion 5211 and the boss portion 5212, is substantially the same as the axial length of the nut side peripheral wall portion 5232b.

[0099] In addition, the radius of the boss portion 5212 is smaller than the radius of the opening formed in the bottom wall portion 5232d. Therefore, when the limiting mechanism 520 is assembled to the ball nut 10, the boss portion 5212 is inserted through the opening formed in the bottom wall portion 5232d of the housing 523. Thus, the meshing length between the nut 521 and the screw shaft 101 can be ensured, and the housing 523 can be miniaturized.

[0100] <2.2. Method for manufacturing ball screw unit>

[0101] Fig.11A as well as Fig. 11B The diagram is for explaining the manufacturing process of the ball screw unit 501 .

[0102] In S21, the ball nut 10 as an example of a moving body is assembled to the screw shaft 101. In other words, this step is a step of preparing a ball screw including a ball nut and a screw shaft.

[0103] In S22 , the disc spring 522 is assembled to the screw shaft 101 .

[0104] In S23 , the nut 521 is fitted into the screw shaft 101 . At this time, the nut 521 is tightened toward the ball nut 10 until the plurality of disc springs 522 come into close contact, thereby applying the biasing force of the disc springs 522 to the nut 521 .

[0105] In S24, the nut 521 is rotated by a predetermined amount to be loosened. This step is a step for adjusting the biasing force of the disc spring 522, and the rotation angle of the nut 521 can be adjusted as appropriate.

[0106] In S25, the housing 523 is inserted into the screw shaft 101. In S26, the nut 521 is restricted to be unable to rotate relative to the housing 523 by the screwing member 24. That is, the screwing member 24 is screwed in a manner that penetrates the through hole 5235, and the front end of the screwing member 24 is inserted into the groove 5213 of the nut 521, thereby restricting the relative rotation of the nut 21 and the housing 23.

[0107] Here, in this embodiment, a plurality of grooves 5213 are provided on the nut 521, and a plurality of through holes 5235 are provided on the housing 523. Moreover, in a state where the screw-in component 24 is screwed with any one of the plurality of through holes 5235, the nut 521 is restricted from rotating relative to the housing 523 by inserting the front end of the screw-in component 24 into any one of the plurality of grooves 5213. Moreover, at this time, in this embodiment, which through hole 5235 and which groove 5213 to use can be appropriately selected according to the circumferential positional relationship between the nut 521 and the housing 523. The following is a detailed description.

[0108] Fig.12 : is a diagram illustrating the relationship between the groove 5213 of the nut 521 and the through hole 5235 of the housing 523. In this embodiment, a plurality of grooves 5213 (grooves 5213a to 5213h) arranged in the circumferential direction are formed on the outer peripheral surface of the nut 521. In addition, a plurality of through holes 5235 (through holes 5235a to 5235e) arranged in the circumferential direction are formed on the housing 523. Fig.12 In the state, the through hole 5235c and the groove 5213d overlap in the circumferential direction. Therefore, by screwing the screw member 524 with the through hole 5235c and inserting the front end of the screw member 524 into the groove 5213d, the relative rotation of the nut 21 and the housing 23 is restricted.

[0109] In addition, in the present embodiment, the center angle θ1 formed by the adjacent grooves 5213c, 5213d and the center axis 101b of the screw shaft 101 is different from the center angle θ2 formed by the adjacent through holes 5235b, 5235c and the center axis 101b. As a result, when the housing 523 is inserted into the screw shaft 101, the plurality of grooves 5213 and the plurality of through holes 5235 are easily overlapped in the circumferential direction. Therefore, it is easier to limit the relative rotation of the nut 521 and the housing 523. For example, in the case of the center angle θ1 = 30° and the center angle θ2 = 45°, any one of the grooves 5213 overlaps with the through hole 5235 every 15°. Therefore, the position of the nut 521 can be specified with a 15° scale. On the other hand, compared with the case of the center angle θ1 = θ2 = 15°, the interval between the grooves 5213 and the through holes 5235 becomes larger, so that the strength degradation of the nut 521 and the housing 523 can be suppressed.

[0110] It should be noted that the number and center angle θ1 of the plurality of grooves 5213, and the number and center angle θ2 of the plurality of through holes 5235 can be appropriately designed. In addition, the intervals between the plurality of grooves 5213 and the plurality of through holes 5235 can also be uneven. In other words, the center angle formed by two adjacent grooves in the plurality of grooves 5213 and the center axis 101b can be not fixed, and the center angle formed by two adjacent through holes in the plurality of through holes 5235 and the center axis 101b can also be not fixed.

[0111] In S27 , the housing 523 is mounted on the ball nut 10 . That is, the ball nut 10 and the housing 523 are fastened together by the bolts 30 .

[0112] <3. Other Implementation Methods>

[0113] The ball screw unit 1 is not limited to the slider unit U1 , and can be applied to other units. For example, it can be used for opening and closing a vacuum gate valve, etc. In this case, by using the restriction mechanism 20 , the free fall of the ball nut 10 can be suppressed.

[0114] The present invention is not limited to the above-described embodiment, and various modifications and changes can be made within the scope of the gist of the invention.

[0115] Description of Reference Numerals

[0116] 1: Ball screw unit, 10: Ball nut, 20: Limiting mechanism, 21: Nut, 22: Coil spring, 23: Housing.

Claims

1. A ball screw unit, mounted on a screw shaft, wherein the ball screw unit comprises: a moving body capable of moving in the axial direction of the screw shaft as the moving body rotates relative to the screw shaft; and a limiting mechanism for limiting the relative rotation between the screw shaft and the moving body, The moving body includes an axial end surface having an opening for inserting the screw shaft. The restriction mechanism includes a detachable portion detachably connected to the end surface of the movable body.

2. The ball screw unit according to claim 1, characterized in that The limiting mechanisms include: a first restricting member that restricts relative rotation between the screw shaft and the moving body by a friction force generated between the first restricting member and the screw shaft; and a housing, the housing housing the first limiting member, The housing includes the mounting and dismounting portion.

3. The ball screw unit according to claim 2, characterized in that The limiting mechanism includes a force applying member that applies a force to the first limiting member relative to the screw shaft to generate the friction force.

4. The ball screw unit according to claim 2, characterized in that The moving body and the housing are fastened together by a fastening member.

5. The ball screw unit according to claim 4, characterized in that The moving body and the housing can be attached and detached by fastening with bolts. The housing is provided with a bolt hole as the mounting and dismounting portion through which a bolt passes in the axial direction. The housing includes a first end and a second end in the axial direction. The housing is mounted on the moving body at the first end. A recessed portion is formed in the second end portion, the recessed portion being recessed so that a head of a bolt passing through the bolt hole does not protrude in the axial direction relative to the second end portion.

6. The ball screw unit according to claim 2, characterized in that In the axial direction, the entire first restricting member is accommodated in the housing.

7. The ball screw unit according to claim 1, wherein: The limiting mechanisms include: a nut, the nut being composed of a raw material having self-lubricating properties and being embedded in the screw shaft; a force-applying component, wherein the force-applying component applies force to the nut in the axial direction to generate friction between the nut and the screw shaft; a housing that accommodates the nut and the force-applying member; and A second limiting member is provided to limit the nut so as to be unable to rotate relative to the housing.

8. The ball screw unit according to claim 7, characterized in that The housing includes a wall portion forming a receiving space for receiving the nut and the force applying member. The wall portion comprises: a peripheral wall portion, the peripheral wall portion forming a side surface of the receiving space; and a bottom wall portion, the bottom wall portion forming one end portion of the accommodation space in the axial direction, The urging member is arranged between the nut and the bottom wall portion.

9. The ball screw unit according to claim 8, characterized in that The peripheral wall portion comprises: a first peripheral wall portion, the first peripheral wall portion forming a side surface of a first accommodation space for accommodating the nut; and a second peripheral wall portion, the second peripheral wall portion forming a side surface of a second accommodation space for accommodating the force applying member, The wall portion includes a connecting wall portion extending in the radial direction of the screw shaft so as to connect the first peripheral wall portion and the second peripheral wall portion. The nut and the connecting wall portion overlap when viewed in the axial direction of the screw shaft.

10. The ball screw unit according to claim 7, wherein: The housing includes a wall portion forming a receiving space for receiving the nut and the force applying member. The wall portion comprises: a peripheral wall portion, the peripheral wall portion forming a side surface of the receiving space; and a bottom wall portion, the bottom wall portion forming one end portion of the accommodation space in the axial direction, The nut is arranged between the urging member and the bottom wall portion.

11. The ball screw unit according to claim 10, characterized in that The peripheral wall portion comprises: a first peripheral wall portion, the first peripheral wall portion forming a side surface of a first accommodation space for accommodating the nut; and a second peripheral wall portion, the second peripheral wall portion forming a side surface of a second accommodation space for accommodating the force applying member, The wall portion includes a connecting wall portion extending in the radial direction of the screw shaft so as to connect the first peripheral wall portion and the second peripheral wall portion. The urging member and the connecting wall portion overlap each other when viewed in the axial direction of the screw shaft.

12. The ball screw unit according to claim 7, wherein: A groove extending in the axial direction is formed on the outer peripheral surface of the nut. A through hole is formed in the housing and penetrates along the radial direction of the screw shaft. The second limiting member is a screw-engaged member screwed into the through hole. By inserting the front end portion of the second restricting member into the groove in a state where the second restricting member is screwed into the through hole, the nut can be moved in the axial direction but cannot be rotated relative to the housing.

13. The ball screw unit according to claim 7, wherein: A plurality of grooves extending in the axial direction of the screw shaft are arranged on the outer peripheral surface of the nut along the circumferential direction of the screw shaft. The housing is provided with a plurality of through holes arranged in the circumferential direction and extending in the radial direction of the screw shaft. The second limiting member is a screw-engaged member screwed into the plurality of through holes. In a state where the second limiting member is screwed into any one of the plurality of through holes, by inserting the front end of the second limiting member into any one of the plurality of grooves, the nut can move in the axial direction but cannot rotate relative to the housing. A center angle formed by two adjacent grooves among the plurality of grooves arranged in the circumferential direction and the center axis of the screw shaft is different from a center angle formed by two adjacent through holes among the plurality of through holes arranged in the circumferential direction and the center axis.

14. The ball screw unit according to claim 10, wherein: The nut includes a contact portion that contacts the force applying member and a boss portion that extends from the contact portion in the axial direction of the screw shaft. In a state where the ball screw unit is assembled to the screw shaft, at least a portion of the boss portion enters an opening formed in the bottom wall portion and through which the screw shaft passes.

15. A slider unit, characterized in that: have: The ball screw unit according to any one of claims 1 to 14; a screw shaft inserted into the ball screw unit; and A support portion rotatably supports the screw shaft.

16. The slider unit according to claim 15, characterized in that The mobile body has: a first moving body; and The second moving body, The first movable body, the second movable body, and the restricting mechanism are fastened by common bolts.

17. A limiting unit, which can be applied to a ball screw having a screw shaft and a movable body, wherein the movable body can move in the axial direction of the screw shaft as it rotates relative to the screw shaft, and the limiting unit limits the relative rotation of the screw shaft and the movable body, characterized in that: The restriction unit includes a detachable portion detachably connected to an axial end surface of the movable body in which an opening is formed for inserting the screw shaft.

18. The restriction unit according to claim 17, characterized in that The limiting unit comprises: a nut, the nut being composed of a raw material having self-lubricating properties and being embedded in the screw shaft; a force-applying component, wherein the force-applying component applies force to the nut in the axial direction to generate friction between the nut and the screw shaft; a housing, the housing accommodating the nut and the force-applying member; as well as A second limiting member is provided to limit the nut so as to be unable to rotate relative to the housing.

19. The restriction unit according to claim 18, characterized in that The housing includes a detachable portion detachably connected to the moving body. In the axial direction, the nut and the urging member are entirely accommodated in the housing.

20. The restriction unit according to claim 18, characterized in that The moving body and the housing can be attached and detached by fastening with bolts. The housing is provided with a bolt hole as the mounting and dismounting portion through which a bolt passes in the axial direction. The housing includes a first end and a second end in the axial direction. The housing is mounted on the moving body at the first end. A recessed portion is formed in the second end portion, the recessed portion being recessed so that a head of a bolt passing through the bolt hole does not protrude in the axial direction relative to the second end portion.

21. The restriction unit according to claim 18, characterized in that The housing includes a wall portion forming a receiving space for receiving the nut and the force applying member. The wall portion comprises: a peripheral wall portion, the peripheral wall portion forming a side surface of the receiving space; and a bottom wall portion, the bottom wall portion forming one end portion of the accommodation space in the axial direction, The urging member is arranged between the nut and the bottom wall portion.

22. The restriction unit according to claim 21, characterized in that The peripheral wall portion comprises: a first peripheral wall portion, the first peripheral wall portion forming a side surface of a first accommodation space for accommodating the nut; and a second peripheral wall portion, the second peripheral wall portion forming a side surface of a second accommodation space for accommodating the force applying member, The wall portion includes a connecting wall portion extending in the radial direction of the screw shaft so as to connect the first peripheral wall portion and the second peripheral wall portion. The nut and the connecting wall portion overlap when viewed in the axial direction of the screw shaft.

23. The restriction unit according to claim 18, characterized in that The housing includes a wall portion forming a receiving space for receiving the nut and the force applying member. The wall portion comprises: a peripheral wall portion, the peripheral wall portion forming a side surface of the receiving space; and a bottom wall portion, the bottom wall portion forming one end portion of the accommodation space in the axial direction, The nut is arranged between the urging member and the bottom wall portion.

24. The restriction unit according to claim 23, characterized in that The peripheral wall portion comprises: a first peripheral wall portion, the first peripheral wall portion forming a side surface of a first accommodation space for accommodating the nut; and a second peripheral wall portion, the second peripheral wall portion forming a side surface of a second accommodation space for accommodating the force applying member, The wall portion includes a connecting wall portion extending in the radial direction of the screw shaft so as to connect the first peripheral wall portion and the second peripheral wall portion. The urging member and the connecting wall portion overlap each other when viewed in the axial direction of the screw shaft.

25. The restriction unit according to claim 18, characterized in that A groove extending in the axial direction is formed on the outer peripheral surface of the nut. The housing includes a through hole extending along the radial direction of the screw shaft. The second limiting member is a screw-engaged member screwed into the through hole. By inserting the front end portion of the second restricting member into the groove in a state where the second restricting member is screwed into the through hole, the nut can be moved in the axial direction but cannot be rotated relative to the housing.

26. The restriction unit according to claim 18, characterized in that A plurality of grooves extending in the axial direction of the screw shaft are arranged on the outer peripheral surface of the nut along the circumferential direction of the screw shaft. The housing is provided with a plurality of through holes arranged in the circumferential direction and extending in the radial direction of the screw shaft. The second limiting member is a screw-engaged member screwed into the plurality of through holes. In a state where the second limiting member is screwed into any one of the plurality of through holes, by inserting the front end of the second limiting member into any one of the plurality of grooves, the nut can move in the axial direction but cannot rotate relative to the housing. A center angle formed by two adjacent grooves among the plurality of grooves arranged in the circumferential direction and the center axis of the screw shaft is different from a center angle formed by two adjacent through holes among the plurality of through holes arranged in the circumferential direction and the center axis.

27. The restriction unit according to claim 23, characterized in that The nut includes a contact portion that contacts the force applying member and a boss portion that extends from the contact portion in the axial direction of the screw shaft. When the ball screw is assembled to the screw shaft, at least a portion of the boss portion enters an opening formed in the bottom wall portion and through which the screw shaft passes.

28. A method for manufacturing a ball screw unit, which is a method for manufacturing a ball screw unit mounted on a screw shaft, characterized in that: The ball screw unit comprises: a moving body capable of moving in the axial direction of the screw shaft as the moving body rotates relative to the screw shaft; and a limiting mechanism for limiting the relative rotation between the screw shaft and the moving body, The limiting mechanisms include: a nut, the nut being embedded in the screw shaft; A force-applying component, wherein the force-applying component applies force to the nut in the axial direction; a housing that accommodates the nut and the force-applying member; and a limiting component, wherein the limiting component limits the nut to be unable to rotate relative to the housing, The manufacturing method comprises the following steps: Assembling the moving body to the screw shaft; embedding the nut into the screw shaft; By inserting a housing containing the force applying member into the screw shaft, the force applying member applies force to the nut relative to the screw shaft; The nut is restricted by the restriction member so as to be unable to rotate relative to the housing; and The housing is coupled to the moving body.

29. A method for manufacturing a ball screw unit, which is a method for manufacturing a ball screw unit mounted on a screw shaft, characterized in that: The ball screw unit comprises: a moving body capable of moving in the axial direction of the screw shaft as the moving body rotates relative to the screw shaft; and a limiting mechanism for limiting the relative rotation between the screw shaft and the moving body, The limiting mechanisms include: a nut, the nut being embedded in the screw shaft; A force-applying component, wherein the force-applying component applies force to the nut in the axial direction; a housing that accommodates the nut and the force-applying member; and a limiting component, wherein the limiting component limits the nut to be unable to rotate relative to the housing, The manufacturing method comprises the following steps: Assembling the moving body to the screw shaft; Assembling the force-applying component to the screw shaft; The nut is inserted into the screw shaft, and the nut is urged relative to the screw shaft by the urging member disposed between the moving body and the nut. inserting the housing into the screw shaft; The nut is restricted by the restriction member so as to be unable to rotate relative to the housing; and The housing is coupled to the moving body.

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