Ball screw unit, slider unit, and regulation unit

Abstract

Provided is a ball screw unit mounted to a screw shaft, the ball screw unit comprising a moving body which can move in the axial direction of the screw shaft as the moving body relatively rotates with respect to the screw shaft and a restriction mechanism which restricts the relative rotation between the screw shaft and the moving body. The moving body includes an end surface in the axial direction in which an opening is formed, the screw shaft being inserted into the opening. The restriction mechanism includes an attachment / detachment unit that is detachably coupled to the end surface of the moving body.

Description

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

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

[0002] A ball screw is known as a mechanism for converting rotational motion into linear motion. A ball screw may be provided with a mechanism for generating a force (braking force) that resists the movement of the ball nut in order to suppress free fall when the screw shaft is arranged vertically or inertial movement when the screw shaft is arranged horizontally (see, for example, Patent Document 1).

[0003] Japanese Utility Model Application Publication No. 59-144253

[0004] In the above-mentioned conventional technology, an air compressor is used to press the protrusions of the piston against the thread grooves of the screw shaft, thereby generating a force that resists the movement of the ball nut. However, in the above-mentioned conventional technology, the use of an air compressor may result in an increase in the size of the mechanism. In addition, the structure for attaching the piston to the ball nut may become complicated, which may affect manufacturing costs, etc.

[0005] The present invention provides a mechanism that generates a force that resists movement of the ball nut with a simpler configuration.

[0006] According to the present invention, there is provided a ball screw unit attached to a screw shaft, comprising: a moving body that is movable in the axial direction of the screw shaft in association with relative rotation with respect to the screw shaft; and a regulating mechanism that regulates the relative rotation between the screw shaft and the moving body, wherein the moving body includes an axial end face formed with an opening through which the screw shaft is inserted, and the regulating mechanism includes a detachable portion that is detachably connected to the end face of the moving body.

[0007] According to the present invention, it is possible to provide a mechanism that generates a force that resists the movement of the ball nut with a simpler configuration.

[0008] 5A . An external perspective view of a ball screw unit according to one embodiment. An exploded perspective view of the ball screw unit. A cross-sectional view for explaining the internal structure of the ball screw unit. A partially enlarged view of FIG. 3. A side view of a housing. A view seen in the direction of arrow B in FIG. 5A. A view seen in the direction of arrow C in FIG. 5A. A cross-sectional view along line V-V in FIG. 5B. A view for explaining a manufacturing process of the ball screw unit. A perspective view schematically showing the configuration of a slider unit. A view for explaining the fastening structure of a ball nut, a regulating mechanism, and a slider. An exploded perspective view of a ball screw unit according to one embodiment. A cross-sectional view for explaining the internal structure of the ball screw unit of FIG. 9. A view for explaining a manufacturing process of the ball screw unit. A view for explaining a manufacturing process of the ball screw unit. A view for explaining the relationship between a groove in a nut and a through hole in a housing.

[0009] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention as claimed, and not all combinations of features described in the embodiments are necessarily essential to the invention. Two or more of the features described in the embodiments may be arbitrarily combined. Furthermore, the same reference numerals are used for the same or similar components, and redundant descriptions will be omitted.

[0010] <1. First Embodiment> <1.1. Ball Screw Unit> <1.1.1. Overview> Fig. 1 is an external perspective view of a ball screw unit 1 according to one embodiment. Fig. 2 is an exploded perspective view of the ball screw unit 1. Fig. 3 is a cross-sectional view for explaining the internal structure of the ball screw unit 1. The ball screw unit 1 is attached to a screw shaft 101 and is movable in the axial direction relative to the screw shaft 101. The ball screw unit 1 includes a ball nut 10 and a restriction mechanism 20.

[0011] <1.1.2. Ball Nut> The ball nut 10 is an example of a movable body that can move in the axial direction of the screw shaft 101 (hereinafter, may be simply referred to as the axial direction) as it rotates relative to the screw shaft 101. A known mechanism can be appropriately adopted as the ball nut 10. In this embodiment, the ball nut 10 includes a main body 11 and a flange 12. The main body 11 is fitted onto the screw shaft 101 via balls (not shown). This converts the rotational motion of the screw shaft 101 into linear motion of the ball nut 10. The main body 11 also forms a circulation path for the balls (not shown).

[0012] Flange 12 is formed to extend outward from main body 11 in the radial direction (hereinafter sometimes simply referred to as the radial direction) of screw shaft 101. Flange 12 is formed with a plurality of bolt holes 121 that penetrate in the axial direction. In a general-purpose ball nut 10, these bolt holes 121 can be used to attach an object to be moved (for example, slider 203, described below) to ball nut 10.

[0013] 1.1.3. Restriction Mechanism The restriction mechanism 20 restricts the relative rotation between the screw shaft 101 and the ball nut 10. In other words, the restriction mechanism 20 generates a force (braking force) that resists movement of the ball nut 10 relative to the screw shaft 101. In this embodiment, the restriction mechanism 20 is configured to be detachable from the ball nut 10. As will be described in detail later, the restriction mechanism 20 is detachable from a ball nut 10 that does not have an accommodation space for accommodating the restriction mechanism 20. The restriction mechanism 20 includes a housing 23, a nut 21, a coil spring 22, and a threaded member 24.

[0014] In the present embodiment, the state in which the relative rotation is restricted by the restriction mechanism 20 may be a state in which the torque required for the relative rotation between the screw shaft 101 and the ball nut 10 is greater than when the restriction mechanism 20 is not provided. That is, it is sufficient that the restriction mechanism 20 generates a braking force that restricts the relative rotation between the screw shaft 101 and the ball nut 10, and the degree of restriction by the restriction mechanism 20 (the magnitude of the braking force) can be set appropriately. For example, when the ball screw unit 1 is used so that the axial direction of the screw shaft 101 is horizontal, the relative rotation may be restricted to a degree that suppresses inertial movement when a moving body including the ball nut 10 stops. Alternatively, when the ball screw unit 1 is used so that the axial direction of the screw shaft 101 is vertical, the relative rotation may be restricted to a degree that suppresses falling due to gravity when a moving body including the ball nut 10 stops. Furthermore, when a torque greater than the braking force generated by the restriction 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.

[0015] Furthermore, in this embodiment, the restriction mechanism 20 is detachable from the ball nut 10, which is an example of a moving body. However, the restriction mechanism 20 may also be detachable from another moving body that is transported together with the ball nut 10. For example, when the ball screw unit 1 is applied to a slider unit U1 described below, the restriction mechanism 20 may be detachable from the slider 203 instead of the ball nut 10. In other words, it is sufficient that the restriction mechanism 20 is detachable from a moving body that includes the ball nut 10.

[0016] (Nut and Coil Spring) The nut 21 is an example of a restricting member that restricts relative rotation between the screw shaft 101 and the ball nut 10 by a frictional force (braking force) generated between the nut 21 and the screw shaft 101. The nut 21 is a cylindrical member that is fitted onto the screw shaft 101, and includes a groove 211 formed on its outer circumferential surface and a screw thread 212 formed on its inner circumferential surface. The groove 211 is formed to extend in the axial direction. As will be described in detail later, the relative rotation between the nut 21 and the housing 23 is restricted by inserting the tip of the threaded member 24 into the groove 211.

[0017] Furthermore, in this embodiment, the nut 21 is made of a material having self-lubricating properties. For example, the nut 21 is formed using a material impregnated with lubricating oil. In one embodiment, the nut 21 may contain a resin material. By making the nut 21 contain a material having self-lubricating properties, wear of the nut 21 and the screw shaft 101 can be suppressed. Furthermore, as the nut 21 moves axially relative to the screw shaft 101, a lubricant is applied to the screw shaft 101. Therefore, there is no need to provide a member for supplying a lubricant such as grease to a ball (not shown), and the number of parts is reduced.

[0018] The coil spring 22 is an example of a biasing member that biases the nut 21 against the screw shaft 101 so as to generate a frictional force between the nut 21 and the screw shaft 101. Other members such as a leaf spring or a disc spring, which will be described later, can also be used as the biasing member.

[0019] 4 is a partially enlarged view of FIG. 3 and is a diagram illustrating the restriction of relative rotation between the screw shaft 101 and the ball nut 10 by the restriction mechanism 20. The coil spring 22 biases the nut 21 in one axial direction, causing a portion of the thread 212 of the nut 21 on one axial side to abut against a portion of the thread 101 a of the screw shaft 101 on the other axial side. As a result, a certain frictional force corresponding to the biasing force of the coil spring 22 is generated between the nut 21 and the screw shaft 101 as a resistance force against the rotation of the screw shaft 101. The restriction mechanism 20 allows relative rotation of the screw shaft 101 with respect to the nut 21 when, for example, a torque exceeding the frictional force is transmitted to the screw shaft 101 from a drive source 202 (described later), and restricts relative rotation of the screw shaft 101 with respect to the nut 21 when a torque less than the frictional force is transmitted to the screw shaft 101.

[0020] In this embodiment, the nut 21 and the coil spring 22 are used to restrict relative rotation between the ball nut 10 and the screw shaft 101. Therefore, compared to restricting the relative rotation using, for example, an electromagnetic brake or an actuator such as an air compressor, the structure can be simplified and the device can be made smaller. Furthermore, in this embodiment, the relative rotation is restricted by a mechanical mechanism, which reduces energy consumption compared to restricting the relative rotation by driving an actuator. Furthermore, the restricted state of relative rotation can be maintained even during a power outage at the facility, for example.

[0021] Furthermore, by adjusting the magnitude of the force (biasing force) with which the coil spring 22 biases the nut 21, it is possible to adjust the frictional force between the nut 21 and the screw shaft 101. In other words, by adjusting the magnitude of the biasing force, it is possible to adjust the magnitude of the braking force generated by the restriction mechanism 20.

[0022] (Housing) Please refer to Figures 5A to 5D in addition to Figures 1 to 3. Figure 5A is a side view of the housing 23. Figure 5B is a view taken in the direction of the arrow B in Figure 5A. Figure 5C is a view taken in the direction of the arrow C in Figure 5A. Figure 5D is a cross-sectional view taken along line VV in Figure 5B.

[0023] The housing 23 accommodates the nut 21 and the coil spring 22. The housing 23 includes a plurality of bolt holes 231 that penetrate the housing 23 in the axial direction. The bolt holes 231 are an example of a detachable portion that detachably couples to the ball nut 10. Bolts 30, which are an example of fastening members, are inserted into the bolt holes 121 of the ball nut 10 and the bolt holes 231 of the housing 23 and fastened to couple the ball nut 10 and the restriction mechanism 20. In other words, the restriction mechanism 20 can be detachably attached to the ball nut 10 by fastening the bolts while housing the nut 21 and the coil spring 22. Note that the manner of fastening using the bolts 30 can be changed as appropriate. For example, the ball nut 10 and the housing 23 of the restriction mechanism 20 may be fastened to each other using the bolts 30 and a nut (not shown), or a groove that threads onto the bolts 30 may be formed in either the bolt holes 121 or the bolt holes 231.

[0024] Furthermore, in this embodiment, the restriction mechanism 20 is detachably coupled to the end face 13 of the ball nut 10. Here, the end face 13 is the axial end face of the ball nut 10 in which an opening is formed, through which the screw shaft 101 is inserted. In this way, because the restriction mechanism 20 is detachably attached to the end face 13 of the ball nut 10, which is an example of a moving body, it is not necessary to form a space on the ball nut 10 side to accommodate the components of the restriction mechanism 20. This makes it possible to simplify the structure of the ball nut 10.

[0025] The housing 23 also includes axial ends 233 and 234. The end 233 is attached to the ball nut 10. Specifically, the end 233 contacts the end face 13 of the ball nut 10 when the ball nut 10 and the restriction mechanism 20 are coupled. Meanwhile, the end 234 is axially farther from the ball nut 10 than the end 233. In this embodiment, the end 234 is formed with a recess 234a so that the head 30a of the bolt 30 passing through the bolt hole 231 does not protrude axially relative to the end 234. This prevents the head 30a of the bolt 30 from protruding, thereby reducing the size of the ball screw unit 1 in the axial direction. FIG. 5A shows the position of the head 30a when the bolt 30 is inserted into the bolt hole 231.

[0026] In this embodiment, bolt hole 231 is arranged so as to overlap bolt hole 121 of ball nut 10 when viewed in the axial direction of screw shaft 101 with screw shaft 101 passing through the inside of housing 23. Therefore, it is possible to connect restriction mechanism 20 and ball nut 10 using bolt hole 121, which is normally provided in ball nut 10 and is used to attach a member to be moved. Therefore, ball nut 10 does not require a dedicated structure for attaching restriction mechanism 20. In other words, restriction mechanism 20 is detachable from so-called general-purpose ball nut 10.

[0027] The internal structure of the housing 23 will be described in detail. The housing 23 includes a wall portion 232 that forms an accommodation space 25 that accommodates the nut 21 and the coil spring 22. The wall portion 232 includes a peripheral wall portion 2321 that forms a side surface of the accommodation space 25, and a bottom wall portion 2322 that forms one end portion 251 of the accommodation space 25 in the axial direction. The bottom wall portion 2322 is formed to extend from the peripheral wall portion 2321 radially inward of the screw shaft 101. Note that the other end of the accommodation space 25, which is opposite to the one end portion 251 in the axial direction, is defined by the end face 13 of the ball nut 10 when the restriction mechanism 20 is connected to the ball nut 10.

[0028] In this embodiment, the coil spring 22 is disposed between the nut 21 and the bottom wall portion 2322. With this arrangement, the bottom wall portion 2322 functions as a seating surface for the coil spring 22. Therefore, it is not necessary to form a seating surface for the coil spring 22 on the ball nut 10 side, and the structure of the ball nut 10 can be simplified.

[0029] In this embodiment, the accommodation space 25 includes a nut accommodation portion 25a that accommodates the nut 21 and a coil spring accommodation portion 25b that accommodates the coil spring 22. The peripheral wall portion 2321 includes a nut-side peripheral wall portion 2321a that forms the side surface of the nut accommodation portion 25a and a spring-side peripheral wall portion 2321b that forms the side surface of the coil spring accommodation portion 25b. The nut accommodation portion 25a is a space that is radially larger than the coil spring accommodation portion 25b. The nut-side peripheral wall portion 2321a and the spring-side peripheral wall portion 2321b are connected by a connecting wall portion 2323 that extends radially.

[0030] In this embodiment, the nut 21 and the connecting wall portion 2323 overlap when viewed in the axial direction of the screw shaft 101. In FIG. 5C , the position of the outer circumferential surface 213 of the nut 21 when the nut 21 is accommodated in the nut accommodating portion 25a is indicated by a dotted line. In the radial direction of the screw shaft 101, the nut 21 is sized so that the outer circumferential surface 213 of the nut 21 is located inside the nut-side circumferential wall portion 2321a and outside the spring-side circumferential wall portion 2321b. As a result, the attachment position of the nut 21 to the screw shaft 101 in the direction approaching the end portion 234 is determined by the connecting wall portion 2323. In other words, since the minimum distance between the nut 21 and the bottom wall portion 2322 is determined in the axial direction of the screw shaft 101, it is possible to set the maximum compression amount of the coil spring 22 to a fixed value.

[0031] Furthermore, in this embodiment, the amount of compression of the coil spring 22 can be adjusted by adjusting the position of the nut 21 relative to the nut accommodating portion 25a in the axial direction, and as a result, the magnitude of the braking force generated by the restriction mechanism 20 can be adjusted. Specifically, in this embodiment, the nut accommodating portion 25a is larger than the nut 21 in the axial direction, allowing for flexibility in the axial positioning of the nut 21 within the nut accommodating portion 25a. However, since the nut 21 is threadedly engaged with the screw shaft 101 and its rotation is restricted by the threading member 24, its axial movement within the nut accommodating portion 25a is restricted. 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 to a range in which the threads 212 of the nut 21 do not interfere with the threads 101a of the screw shaft 101 (in other words, a range corresponding to the backlash between the nut 21 and the screw shaft 101 that are threadedly engaged). Therefore, by positioning the nut 21 at a desired axial position relative to the nut accommodating portion 25a during assembly, it is possible to adjust the amount of compression of the coil spring 22. Furthermore, the closer the nut 21 is to the coil spring accommodating portion 25b within the nut accommodating portion 25a, the greater the amount of compression of the coil spring 22. Conversely, the closer the nut 21 is to the end face 13 of the ball nut 10 within the nut accommodating portion 25a, the smaller the amount of compression of the coil spring 22.

[0032] Furthermore, in this embodiment, the entire nut 21 is housed in the housing 23 in the axial direction. This eliminates the need to provide the ball nut 10 with a structure (such as a countersunk hole) for housing the components of the restriction mechanism 20. Therefore, since there is no need to provide the ball nut 10 with a structure for housing the restriction mechanism 20, the structure of the ball nut 10 can be simplified. Furthermore, since there is no need to provide the ball nut 10 with a structure for housing the restriction mechanism 20, the restriction mechanism 20 can be easily attached to a general-purpose ball nut 10 without the need for special processing.

[0033] The housing 23 is also formed with a through hole 235 that penetrates in the radial direction of the screw shaft 101. The through hole 235 has an inner surface formed with a thread groove into which the threaded member 24 is threaded.

[0034] (Threaded Member) The threaded member 24 restricts the nut 21 so that it cannot rotate relative to the housing 23. The threaded member 24 is threaded into the through hole 235. For example, the threaded member 24 may be a set screw or the like. In this embodiment, when the threaded member 24 is threaded into the through hole 235, the tip of the threaded member 24 is inserted into the groove 211, so that the nut 21 can move in the axial direction but cannot rotate relative to the housing 23.

[0035] More specifically, because the groove 211 is formed along the axial direction, the tip of the threaded member 24 does not interfere with the nut 21 when the nut 21 and the housing 23 move relative to each other in the axial direction. Therefore, the nut 21 and the housing 23 are capable of relative movement in the axial direction. However, in relation to the screw shaft 101, when there is no relative rotation between the nut 21 and the screw shaft 101, the relative movement of the nut 21 in the axial direction is limited to the range of backlash between the nut 21 and the screw shaft 101 that are threadedly engaged with each other, as described above. Therefore, as a result, the nut 21 is also capable of relative movement in the axial direction with respect to the housing 23 within the range of backlash between the nut 21 and the screw shaft 101 that are threadedly engaged with each other.

[0036] On the other hand, when the nut 21 attempts to rotate relative to the housing 23, the tip of the threaded member 24 abuts against the surfaces of the groove 211 extending in the axial and radial directions. This disables the nut 21 from rotating relative to the housing 23. In this manner, in this embodiment, the restriction of rotation of the nut 21 can be achieved with a simple configuration using the threaded member 24. Note that, although the threaded member 24 disables the relative rotation between the nut 21 and the housing 23 in this embodiment, the relative rotation may be restricted by another member such as a pin. In this case, the pin may be press-fitted into the through hole 235.

[0037] As described above, this embodiment provides a mechanism with a simple configuration that generates a force (braking force) that resists movement of the ball nut 10. Furthermore, since the mechanism can be easily attached to a general-purpose ball nut 10, the restriction mechanism 20 can be easily used as a common part. Furthermore, the braking force (biasing force) can be adjusted and attached independently of the moving body, using only the restriction mechanism 20, which is separate from the moving body such as the ball nut 10.

[0038] 1.2 Manufacturing Method of Ball Screw Unit Next, a description will be given of a manufacturing method of the ball screw unit 1. FIG.

[0039] In S1, the ball nut 10, which is 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.

[0040] In S2, the nut 21 is fitted onto the screw shaft 101. In S3, a housing 23 containing a coil spring 22, which is an example of a biasing member, is inserted into the screw shaft 101, whereby the coil spring 22 biases the nut 21 against the screw shaft 101.

[0041] In S4, the nut 21 is restricted by the threaded member 24 so as to be unable to rotate relative to the housing 23. That is, the threaded member 24 is threaded so as to pass through the through-hole 235, and the tip of the threaded member 24 is inserted into the groove 211 of the nut 21, thereby restricting the relative rotation between the nut 21 and the housing 23. In S5, the housing 23 is attached to the ball nut 10. That is, the ball nut 10 and the housing 23 are fastened together by the bolt 30.

[0042] As described above, in this embodiment, the restriction mechanism 20 can be easily attached to the ball nut 10 .

[0043] <1.3. Slider Unit> A slider unit U1 will be described, which is an application example of the ball screw unit 1. Fig. 7 is a perspective view that schematically shows the configuration of the slider unit U1.

[0044] The slider unit U1 includes a ball screw unit 1, a screw shaft 101, a support portion 201, a drive source 202, a slider 203, and a guide rail 204. The slider unit U1 may be used so that the movement direction of the slider 203 is either horizontal or vertical.

[0045] 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.

[0046] In this embodiment, the ball nut 10 and slider 203 included in the ball screw unit 1 constitute a moving body. That is, when the screw shaft 101 is rotated by the drive source 202, the ball screw unit 1 and the ball nut 10 move together in the axial direction relative to the screw shaft 101. The slider 203 is a member that is to be moved by the ball screw unit 1. For example, a table or the like used for positioning or transporting parts can be attached to the slider 203.

[0047] The guide rail 204 is a member that guides the linear motion of the slider 203. The slider 203 is formed with a groove 2031 that receives the guide rail 204.

[0048] FIG. 8 is a diagram illustrating the fastening structure of the ball nut 10, the restriction mechanism 20, and the slider 203. In this embodiment, the slider 203, the ball nut 10, and the housing 23 of the restriction mechanism 20 are fastened together by a common bolt 31. In a so-called general-purpose ball nut 10, a bolt hole 121 is provided in the flange 12 portion for attaching a member to be moved, such as the slider 203. Therefore, if the restriction mechanism 20 is not provided, these can be fastened together by passing a bolt 31 through this bolt hole 121 and the bolt hole of the slider 203. In this embodiment, by attaching the restriction mechanism 20 to the ball nut 10 using this bolt hole 121, the restriction mechanism 20 can be attached without increasing the number of bolts compared to when the restriction mechanism 20 is not provided. In addition, since the slider 203, the ball nut 10, and the regulating mechanism 20 are fastened together with a common bolt 31, the bolt hole 231 of the regulating mechanism 20 is positioned so as to overlap with the bolt hole 121 of the ball nut 10 when assembled to the screw shaft 101 in the axial direction.

[0049] 2. Second Embodiment 2.1. Ball Screw Unit Fig. 9 is an exploded perspective view of a ball screw unit 501 according to one embodiment. Fig. 10 is a cross-sectional view for explaining the internal structure of the ball screw unit 501 of Fig. 9. Hereinafter, the same components as those in the ball screw unit 1 of the first embodiment will be assigned the same reference numerals, and explanations thereof will be omitted.

[0050] 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.

[0051] The nut 521 is an example of a restricting member that restricts the relative rotation between the screw shaft 101 and the ball nut 10 by a frictional 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 threads 212 formed on the inner circumferential surfaces of the contact portion 5211 and the boss portion 5212.

[0052] The contact portion 5211 is a portion that comes into contact with the disc spring 522. In other words, the contact portion 5211 is a portion that receives the biasing force from the disc spring 522. A plurality of grooves 5213 extending in the axial direction of the screw shaft 101 are formed on the outer circumferential surface of the contact portion 5211. The plurality of grooves 5213 are arranged side by side in the circumferential direction of the screw shaft 101. As will be described in detail later (see FIG. 12 ), the number and arrangement of the plurality of grooves 5213 can be changed as appropriate.

[0053] The boss portion 5212 is a portion that extends in the axial direction from the contact portion 5211. The boss portion 5212 has a smaller diameter than the contact portion 5211. Furthermore, the boss portion 5212 has a smaller diameter than the opening formed in the bottom wall portion 5232d of the housing 523.

[0054] The disc spring 522 is an example of a biasing member that biases the nut 521 against the screw shaft 101 so as to generate a frictional 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, or the like. Although three disc springs 522 are shown here, the number of disc springs 522 used can be changed as appropriate.

[0055] 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.

[0056] The bolt hole 5231 is an example of a detachable portion that detachably couples to the ball nut 10. Bolts 30, which are an example of fastening members, are inserted into the bolt holes 121 of the ball nut 10 and the bolt holes 5231 of the housing 23 and fastened, thereby coupling the ball nut 10 and the restriction mechanism 520. In the example of FIG. 9 , the bolt holes 5231 are provided so that the distance between two diagonally arranged bolt holes 121 of the general-purpose ball nut 10 matches the distance between the two bolt holes 5231 provided in the housing 523. Note that the housing 523 may be provided with three or more bolt holes 121 (for example, four bolt holes corresponding to the four bolt holes 121 of the ball nut 10). Alternatively, the number, positions, etc. of the bolt holes 121 of the ball nut 10 are not limited to the example shown in the figure.

[0057] The wall portion 5232 includes a peripheral side wall portion 5232a that forms a side surface of the accommodation space for the nut 521 and the disc spring 522, and a bottom wall portion 5232d that forms one end 251 of the accommodation space 25 in the axial direction. The bottom wall portion 5232d is formed to extend from the peripheral side wall portion 5232a toward the inside in the radial direction of the screw shaft 101. Note that the other end of the accommodation space 25, which is opposite in the axial direction to the side where the bottom wall portion 5232d is provided, is defined by the end face 13 of the ball nut 10 when the restriction mechanism 520 is connected to the ball nut 10.

[0058] The side circumferential wall portion 5232a includes a nut-side circumferential wall portion 5232b that forms the side surface of the portion of the accommodation space 25 that accommodates the nut 521, and a spring-side circumferential wall portion 5232c that forms the side surface of the portion of the accommodation space 25 that accommodates the disc spring 522. The inner circumferential surface of the spring-side circumferential wall portion 5232c is radially larger than the inner circumferential surface of the nut-side circumferential wall portion 5232b. The nut-side circumferential wall portion 5232b and the spring-side circumferential wall portion 5232c are connected by a connecting wall portion 5232e that extends radially. 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. This allows the disc spring 522 to be sandwiched between the end face of the ball nut 10 and the connecting wall portion 5232e.

[0059] In addition, the nut-side peripheral wall portion 5232b is provided 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 provided between the disc spring 522 and the bottom wall portion 5232d.

[0060] In the present embodiment, through holes 5235 that penetrate the housing 523 in the radial direction of the screw shaft 101 are formed side by side in the circumferential direction. A thread groove into which the threaded member 24 is threaded is formed on the inner surface of the through holes 5235.

[0061] In this embodiment, the length L1 of the disc spring 522 before it is brought into close contact with the ball nut 10 and the nut 521 (i.e., its natural length, see FIG. 12 ) is longer than the axial length L2 of the spring-side peripheral wall portion 5232 c. The axial length of the nut 521, including the contact portion 5211 and the boss portion 5212, is approximately the same as the axial length of the nut-side peripheral wall portion 5232 b.

[0062] Furthermore, 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 restriction mechanism 520 is assembled to the ball nut 10, the boss portion 5212 passes through the opening formed in the bottom wall portion 5232d of the housing 523. This allows the housing 523 to be made smaller while ensuring the engagement length between the nut 521 and the screw shaft 101.

[0063] 2.2. Manufacturing Method of Ball Screw Unit FIGS. 11A and 11B are diagrams for explaining the manufacturing process of the ball screw unit 501. FIG.

[0064] In S21, the ball nut 10, which is 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.

[0065] In S22, the disc spring 522 is assembled to the screw shaft 101.

[0066] In S23, the nut 521 is fitted onto 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 with each other, so that the biasing force of the disc springs 522 is applied to the nut 521.

[0067] In S24, the nut 521 is rotated a predetermined amount to loosen it. This step is for adjusting the biasing force of the disc spring 522, and the rotation angle of the nut 521 can be adjusted as appropriate.

[0068] In S25, the housing 523 is inserted onto the screw shaft 101. In S26, the screwing member 24 restricts the nut 521 from rotating relative to the housing 523. That is, the screwing member 24 is screwed so as to pass through the through-hole 5235, and the tip 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.

[0069] In this embodiment, the nut 521 is provided with a plurality of grooves 5213, and the housing 523 is provided with a plurality of through holes 5235. When the threaded member 24 is threaded into one of the plurality of through holes 5235, the tip of the threaded member 24 is inserted into one of the plurality of grooves 5213, thereby restricting the nut 521 from rotating relatively with respect to the housing 523. In this case, in this embodiment, which through hole 5235 and which groove 5213 to use can be appropriately selected depending on the circumferential positional relationship between the nut 521 and the housing 523. This will be described in detail below.

[0070] 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) are formed in the outer peripheral surface of the nut 521 and aligned in the circumferential direction. Furthermore, a plurality of through holes 5235 (through holes 5235a to 5235e) are formed in the housing 523 and aligned in the circumferential direction. In the state shown in FIG. 12, the through hole 5235c and the groove 5213d overlap in the circumferential direction. Therefore, by threading the threaded member 524 into the through hole 5235c and inserting the tip of the threaded member 524 into the groove 5213d, the relative rotation of the nut 21 and the housing 23 is restricted.

[0071] Furthermore, in this embodiment, the central angle θ1 formed by adjacent grooves 5213c, 5213d and the central axis 101b of the screw shaft 101 is different from the central angle θ2 formed by adjacent through holes 5235b, 5235c and the central axis 101b. This makes it easier for the grooves 5213 and the through holes 5235 to overlap circumferentially when the housing 523 is inserted onto the screw shaft 101. This makes it easier to restrict relative rotation between the nut 521 and the housing 523. For example, when the central angle θ1 = 30° and the central angle θ2 = 45°, one of the grooves 5213 and the through hole 5235 overlaps every 15°. This allows the position of the nut 521 to be determined in 15° increments. Meanwhile, since the spacing between the grooves 5213 and the through holes 5235 is greater than when the central angles θ1 = θ2 = 15°, deterioration in the strength of the nut 521 and the housing 523 can be suppressed.

[0072] The number of grooves 5213 and the central angle θ1, and the number of through holes 5235 and the central angle θ2 can be designed as appropriate. The intervals between the grooves 5213 and the through holes 5235 do not have to be uniform. In other words, the central angle formed by two adjacent grooves 5213 and the central axis 101b among the grooves 5213 does not have to be constant, and the central angle formed by two adjacent through holes 5235 and the central axis 101b does not have to be constant.

[0073] In S27, the housing 523 is attached to the ball nut 10. That is, the ball nut 10 and the housing 523 are fastened together by the bolts 30.

[0074] 3. Other Embodiments The ball screw unit 1 can be applied not only to the slider unit U1 but also to other units. For example, it can be used to open and close a vacuum gate valve. In this case, the restriction mechanism 20 can be used to prevent the ball nut 10 from free falling.

[0075] The invention is not limited to the above-described embodiment, and various modifications and variations are possible within the scope of the gist of the invention.

[0076] 1: ball screw unit, 10: ball nut, 20: restriction mechanism, 21: nut, 22: coil spring, 23: housing

Claims

1. A ball screw unit attached to a screw shaft, comprising: a moving body that is movable in the axial direction of the screw shaft as it rotates relative to the screw shaft; a restricting mechanism that restricts relative rotation of the screw shaft and the moving body; wherein the restricting mechanism includes: a nut that is screwed onto the screw shaft; a biasing member that biases the nut in the axial direction so as to generate a frictional force between the nut and the screw shaft; a housing that is detachably connected to the moving body and houses the nut and the biasing member; a restricting member that is provided on the housing and restricts relative rotation of the nut with respect to the housing. A ball screw unit characterized by the above.

2. The ball screw unit according to claim 1, wherein the moving body includes an end face in the axial direction with an opening into which the screw shaft is inserted, and the housing includes a detachable portion that is detachably connected to the end face of the moving body. A ball screw unit characterized by the above.

3. (Deleted)

4. The ball screw unit according to claim 1, wherein the moving body and the housing are fastened by a fastening member. A ball screw unit characterized by the above.

5. The ball screw unit according to claim 2, wherein the moving body and the housing are detachable by bolt fastening, a bolt hole is formed in the housing as the detachable portion through which the bolt penetrates in the axial direction, the housing includes a first end portion and a second end portion in the axial direction, the housing is attached to the moving body at the first end portion, and a recess is formed at the second end portion so that the head of the bolt passing through the bolt hole does not project axially with respect to the second end portion. A ball screw unit characterized by the above.

6. The ball screw unit according to claim 1, wherein the entire nut is housed in the housing in the axial direction. A ball screw unit characterized by the above.

7. The ball screw unit according to claim 1, wherein the nut is composed of a material having self-lubricity. A ball screw unit characterized by the above.

8. The ball screw unit according to claim 1, wherein the housing includes a wall portion that forms a housing space for housing the nut and the biasing member, and the wall portion includes: a peripheral wall portion that forms a side surface of the housing space; including a bottom wall portion that forms one end portion of the accommodation space in the axial direction; the biasing member is disposed between the nut and the bottom wall portion; A ball screw unit characterized by the above.

9. The ball screw unit according to claim 8, wherein the peripheral wall portion includes a first peripheral wall portion that forms a side surface of a first accommodation space for accommodating the nut, and a second peripheral wall portion that forms a side surface of a second accommodation space for accommodating the biasing member; the wall portion includes a connecting wall portion that extends 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 in the axial direction view of the screw shaft; A ball screw unit characterized by the above.

10. The ball screw unit according to claim 1, wherein the housing includes a wall portion that forms an accommodation space for accommodating the nut and the biasing member; the wall portion includes a peripheral wall portion that forms a side surface of the accommodation space, and a bottom wall portion that forms one end portion of the accommodation space in the axial direction; the nut is disposed between the biasing member and the bottom wall portion; A ball screw unit characterized by the above.

11. The ball screw unit according to claim 10, wherein the peripheral wall portion includes a first peripheral wall portion that forms a side surface of a first accommodation space for accommodating the nut, and a second peripheral wall portion that forms a side surface of a second accommodation space for accommodating the biasing member; the wall portion includes a connecting wall portion that extends in the radial direction of the screw shaft so as to connect the first peripheral wall portion and the second peripheral wall portion; the biasing member and the connecting wall portion overlap in the axial direction view of the screw shaft; A ball screw unit characterized by the above.

12. The ball screw unit according to claim 1, wherein a groove extending in the axial direction is formed on the outer peripheral surface of the nut; a through hole penetrating in the radial direction of the screw shaft is formed in the housing; the restricting member is a screwing member that screws into the through hole; when the restricting member is screwed into the through hole, the tip of the second restricting member is inserted into the groove, whereby the nut is movable in the axial direction while being restricted from relative rotation with respect to the housing; A ball screw unit characterized by the above.

13. The ball screw unit according to claim 1, wherein a plurality of grooves extending in the axial direction of the screw shaft are formed side by side in the circumferential direction of the screw shaft on the outer peripheral surface of the nut; The housing is formed with a plurality of through holes penetrating in the radial direction of the screw shaft and arranged in the circumferential direction. The restricting member is a screwing member that screws into the plurality of through holes. With the restricting member screwed into any one of the plurality of through holes, the tip of the second restricting member is inserted into any one of the plurality of grooves, whereby the nut is movable in the axial direction while relative rotation with respect to the housing is restricted. The central angle formed by two adjacent ones of the plurality of grooves arranged in the circumferential direction and the central axis of the screw shaft is different from the central angle formed by two adjacent ones of the plurality of through holes arranged in the circumferential direction and the central axis. A ball screw unit characterized by this.

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

15. The ball screw unit according to any one of claims 1, 2, 4 to 14, A screw shaft inserted into the ball screw unit, A support portion that rotatably supports the screw shaft, A slider unit characterized by comprising these.

16. The slider unit according to claim 15, The moving body, A first moving body, A second moving body, and has, The first moving body, the second moving body, and the restricting mechanism are fastened by a common bolt. A slider unit characterized by this.

17. Applicable to a ball screw including a screw shaft and a moving body movable in the axial direction of the screw shaft as the screw shaft rotates relative thereto, and a restricting unit that restricts relative rotation of the screw shaft and the moving body, A nut fitted to the screw shaft, A biasing member that biases the nut in the axial direction so that a frictional force is generated between the nut and the screw shaft, A housing that is detachably connected to the moving body and houses the nut and the biasing member, A restricting member provided on the housing and restricting relative rotation of the nut with respect to the housing, and includes, A restricting unit characterized by this.

18. The restricting unit according to claim 17, The nut is configured to include a material having self-lubricity. The regulating unit is characterized by this.

19. The regulating unit according to claim 17, wherein the moving body includes the end face in the axial direction, in which an opening into which the screw shaft is inserted is formed. The housing includes a detachable portion that is detachably connected to the end face of the moving body. In the axial direction, the entire nut and the biasing member are accommodated in the housing. The regulating unit is characterized by this.

20. The regulating unit according to claim 19, wherein the moving body and the housing are detachable by bolt fastening, a bolt hole is formed in the housing as the detachable portion through which the bolt penetrates in the axial direction, the housing includes a first end portion and a second end portion in the axial direction, the housing is attached to the moving body at the first end portion, a recess is formed at the second end portion so that the head of the bolt passing through the bolt hole does not protrude axially with respect to the second end portion. The regulating unit is characterized by this.

21. The regulating unit according to claim 17, wherein the housing includes a wall portion that forms an accommodation space for accommodating the nut and the biasing member, the wall portion includes a peripheral wall portion that forms a side surface of the accommodation space, and a bottom wall portion that forms one end portion of the accommodation space in the axial direction, the biasing member is disposed between the nut and the bottom wall portion. The regulating unit is characterized by this.

22. The regulating unit according to claim 21, wherein the peripheral wall portion includes a first peripheral wall portion that forms a side surface of a first accommodation space for accommodating the nut, and a second peripheral wall portion that forms a side surface of a second accommodation space for accommodating the biasing member, the wall portion includes a connecting wall portion that extends 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 in the axial direction view of the screw shaft. The regulating unit is characterized by this.

23. The regulating unit according to claim 17, wherein the housing includes a wall portion that forms an accommodation space for accommodating the nut and the biasing member, the wall portion includes a peripheral wall portion that forms a side surface of the accommodation space, and a bottom wall portion that forms one end portion of the accommodation space in the axial direction, the nut is disposed between the biasing member and the bottom wall portion. The regulating unit is characterized by this.

24. The regulating unit according to claim 23, wherein the peripheral wall portion includes a first peripheral wall portion forming a side surface of a first accommodation space for accommodating the nut, and a second peripheral wall portion forming a side surface of a second accommodation space for accommodating the biasing 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 biasing member and the connecting wall portion overlap in the axial direction view of the screw shaft, characterized in that it is a regulating unit.

25. The regulating unit according to claim 17, wherein a groove extending in the axial direction is formed on the outer peripheral surface of the nut, the housing includes a through hole penetrating in the radial direction of the screw shaft, the regulating member is a screwing member screwed into the through hole, in a state where the regulating member is screwed into the through hole, the tip of the second regulating member is inserted into the groove, whereby the nut is movable in the axial direction while being restricted from relative rotation with respect to the housing, characterized in that it is a regulating unit.

26. The regulating unit according to claim 17, wherein a plurality of grooves extending in the axial direction of the screw shaft are formed side by side in the circumferential direction of the screw shaft on the outer peripheral surface of the nut, a plurality of through holes penetrating in the radial direction of the screw shaft are formed side by side in the circumferential direction in the housing, the regulating member is a screwing member screwed into the plurality of through holes, in a state where the regulating member is screwed into any one of the plurality of through holes, the tip of the regulating member is inserted into any one of the plurality of grooves, whereby the nut is movable in the axial direction while being restricted from relative rotation with respect to the housing, the central angle formed by two adjacent ones of the plurality of grooves arranged in the circumferential direction and the central axis of the screw shaft is different from the central angle formed by two adjacent ones of the plurality of through holes arranged in the circumferential direction and the central axis, characterized in that it is a regulating unit.

27. The regulating unit according to claim 23, wherein the nut includes a contact portion in contact with the biasing member and a boss portion extending in the axial direction of the screw shaft from the contact portion, in a state where the ball screw is assembled to the screw shaft, at least a part of the boss portion enters an opening formed in the bottom wall portion through which the screw shaft passes, characterized in that it is a regulating unit.

28. (Deleted)

29. (Deleted)

30. The ball screw unit according to claim 1, wherein The nut is provided with an inner peripheral surface formed with a thread that engages with the thread of the screw shaft, and an outer peripheral surface provided with a groove into which the regulating member is inserted, and the groove and the regulating member regulate relative rotation of the nut with respect to the housing, while relative axial movement of the nut with respect to the housing is not regulated. A ball screw unit characterized by this.

31. The ball screw unit according to claim 1, wherein the regulating mechanism is configured to be able to adjust the biasing force of the biasing member with respect to the nut. A ball screw unit characterized by this.

32. The slider unit according to claim 1, further comprising a drive source for rotating the screw shaft, and when torque exceeding the frictional force is transmitted from the drive source to the screw shaft, relative rotation of the screw shaft with respect to the nut is permitted, and when torque lower than the frictional force is transmitted from the drive source to the screw shaft, relative rotation of the screw shaft with respect to the nut is regulated. A slider unit characterized by this.