JP5884410B2 - Lead screw device - Google Patents

Description

  The present invention relates to a feed screw device that linearly moves a moving body by rotational movement.

  The feed screw device is used as a machine element that positions a moving body in a linear direction in various fields such as machine tools and automobiles. In this feed screw device, the thread grooves formed in the shaft member and the nut member are directly meshed, or indirectly meshed via a plurality of balls, and the rotational motion is converted into a linear motion to move the moving body. It is moved. Further, there are a feed screw device that rotates a shaft member to linearly move a nut member, and a device that rotates a nut member to linearly move a shaft member. In any configuration, the feed screw device positions the moving body according to the amount of rotation of the member to be rotated.

  In such a shaft member and a nut member of the feed screw device, a frictional force is generated in each screw groove engaged with each other. Since the frictional force generated in the thread groove may affect the necessary rotational driving force, positioning accuracy, durability of the apparatus, and the like, it is preferable to reduce it as much as possible. Thus, for example, Patent Documents 1 and 2 disclose a method for reducing a frictional force using a vibration generator that generates high-frequency vibration. According to this method, the vibration force generated in the thread groove can be reduced by exciting the shaft member or the nut member with the vibration device.

Japanese Patent Laid-Open No. 06-238540 Japanese Patent Laid-Open No. 2005-256594

In a feed screw device that reduces frictional force using such a vibration device, the effect depends on the setting of the frequency and amplitude at the time of vibration and how the vibration generating member that generates high-frequency vibration is arranged. May fluctuate significantly. Further, since there is a demand for downsizing of the vibration device, it is required to more efficiently vibrate the screw groove to reduce the frictional force.
The present invention has been made in view of the above problems, and provides a feed screw device capable of reducing the frictional force generated in the thread groove by more efficiently exciting the thread groove. Objective.

In order to solve the above-described problem, according to the first aspect of the present invention, a shaft member having a thread groove formed on the outer peripheral surface and a thread groove that meshes with the screw groove of the shaft member are formed on the inner peripheral surface. A nut member, and a vibration generating member that is fixed to one of the shaft member and the nut member and vibrates the screw groove of the one member, and the screw groove of the one member includes the shaft member and The nut member is constituted by a plurality of screw groove portions provided in the axial direction so as to be engaged with the screw groove of the other member, and the vibration generating member is interposed between the screw groove portions. The nut member is controlled so as to relatively vibrate when the nut member is relatively moved in the axial direction with respect to the shaft member, and is relatively moved with respect to the other member. Above The screw groove of the rectangular member vibrated.

According to a second aspect of the present invention, in the first aspect, the one member is integrally formed with a plurality of screw groove main bodies formed separately and provided with the plurality of screw groove portions, and the plurality of screw groove main bodies. possess a connecting portion for connecting the said vibration generating member is a piezoelectric element that vibrates the signal voltage is applied.
According to the invention of claim 3, in claim 1 or 2, when the axial length of the thread groove of the shaft member is longer than the axial length of the thread groove of the nut member, the nut member is The one member is used.

  According to the first aspect of the present invention, the screw groove of one member to which the vibration generating member is fixed among the shaft member and the nut member is constituted by a plurality of screw groove portions spaced in the axial direction. And it is set as the structure which the vibration generating member interposes and fixes between several screw groove parts. Thereby, any one of the plurality of screw groove portions is used as a reference, and the other screw groove portions can be vibrated by the vibration generating member. Conventionally, for example, in Patent Document 1, vibration is applied from the end of the shaft member, and in Patent Document 2, vibration is applied from the end of the nut member. In such a conventional configuration, there is a concern that when the vibration generating member vibrates with reference to the arranged shaft member or nut member, the shaft member or nut member cannot be sufficiently excited. On the other hand, in the present invention, as described above, since at least one of the screw groove portions is a reference, the screw groove can be vibrated more efficiently. Therefore, the frictional force generated in the thread groove can be reduced.

  Further, the plurality of screw groove portions constituting the screw groove are separated from each other in the axial range where the screw groove of the other member on the side where the vibration generating member is not fixed is engaged. That is, the vibration generating member interposed between the plurality of screw groove portions is positioned inside the axial range in which the screw grooves are engaged with each other. Therefore, since vibration is efficiently transmitted from the vibration generating member to each screw groove portion, it is possible to reliably reduce the frictional force generated in the screw groove.

  According to the second aspect of the invention, the one member to which the vibration generating member is fixed integrally connects the plurality of screw groove main bodies formed separately from each other by the connecting portion. Accordingly, any one of the plurality of screw groove main bodies provided with the screw groove is used as a reference, and the other screw groove main bodies can be vibrated by the vibration generating member. Therefore, it is possible to surely vibrate the thread groove and reduce the frictional force.

  According to the invention which concerns on Claim 3, it is set as the structure which fixes a vibration generation member to a nut member. In the feed screw device, the nut member moves linearly relative to the shaft member to position the moving body. In general, the axial length of the thread groove of the shaft member is often longer than the axial length of the thread groove of the nut member, depending on the application. Therefore, by configuring the screw groove of the nut member with a plurality of screw groove portions spaced apart in the axial direction, the vibration generating member interposed therebetween is always located in the vicinity of the screw groove that is subject to excitation, It can be vibrated efficiently.

1st Embodiment: It is sectional drawing which shows the whole feed screw apparatus. It is an expanded sectional view showing meshing of a shaft member and a nut member. 2nd embodiment: It is an expanded sectional view which shows meshing | engagement of a shaft member and a nut member. 3rd embodiment: It is an expanded sectional view which shows meshing | engagement of a shaft member and a nut member.

  DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment in which a feed screw device of the present invention is embodied will be described with reference to the drawings.

<First embodiment>
(Configuration of feed screw device 1)
A feed screw device 1 according to this embodiment will be described with reference to FIGS. 1 and 2. As shown in FIG. 1, the feed screw device 1 includes a shaft member 10, a nut member 20, a drive device 30, and a vibration device 40. In the present embodiment, the feed screw device 1 is configured such that the shaft member 10 is rotated by the drive device 30 and the nut member 20 is linearly moved. Thereby, the moving body 2 provided in the nut member 20 moves in the axial direction along with the linear motion of the nut member 20, and is positioned at a predetermined axial position by the control of the driving device 30.

  The shaft member 10 is a columnar member extending in the axial direction, and a male screw 11 that is a thread groove is formed on the outer peripheral surface from one end to the other end. The shaft member 10 is rotatably supported by a plurality of bearings, and is driven to rotate by a drive device 30 described later.

  As shown in FIGS. 1 and 2, the nut member 20 includes a first nut body 21, a second nut body 22, and a connecting portion 23. The first nut body 21 has an annular shape and is provided with a female screw 21a that is a thread groove on the inner peripheral surface. Similar to the first nut body 21, the second nut body 22 has an annular shape and is provided with a female screw 22 a that is a thread groove on the inner peripheral surface. The first nut main body 21 and the second nut main body 22 are members formed separately, and are spaced apart in the axial direction of the feed screw device 1.

  The female screws 21a and 22a mesh with the male screw 11 of the shaft member 10, respectively. The 1st nut main body 21 and the 2nd nut main body 22 which consist of such a structure correspond to the "screw groove part main body" of this invention. And the thread groove of the nut member 20 is comprised by each internal thread 21a, 22a which is the some thread groove part provided even if it spaced apart in the axial direction.

  The connecting portion 23 is a member that integrally connects the first nut main body 21 and the second nut main body 22 corresponding to a plurality of thread groove main bodies. In the present embodiment, the first nut main body 21 and the second nut main body 22 are inserted through through holes, and both members are connected by bolt fastening. A plurality of connecting portions 23 are provided at equal intervals in the circumferential direction of the first nut main body 21 and the second nut main body 22 each having an annular shape. The connecting portion 23 restricts the relative movement of the second nut body 22 in the circumferential direction with respect to the first nut body 21 so as to be able to transmit the rotational driving force, and allows a minute relative movement in the axial direction. .

  The nut member 20 having such a configuration meshes with the shaft member 10 through the thread grooves so that the rotational motion can be converted into a linear motion. Then, when the shaft member 10 rotates, the nut member 20 moves in the axial direction together with the moving body 2 installed on the outer peripheral side of the second nut body 22 according to the rotation amount. Here, in order to sufficiently secure the movable range of the moving body 2, as shown in FIGS. 1 and 2, the axial length L 1 of the male screw 11 corresponding to the thread groove of the shaft member 10 is set to Each female screw 21a, 22a corresponding to the thread groove is formed longer than the axial length L2. This axial length L2 is equal to the axial range in which the thread grooves (male thread 11 and female threads 21a, 22a) of the shaft member 10 and the nut member 20 are engaged.

  The drive device 30 rotates the shaft member 10 and includes a motor 31 and a coupling 32. The motor 31 is an electric motor that is connected to a control device (not shown) and rotates to a predetermined phase by a current supplied from the control device via a motor amplifier or the like. The motor 31 is connected to one end of a shaft member rotatably supported in the feed screw device 1 via a coupling 32. Thereby, the rotational drive of the motor 31 is transmitted to the shaft member 10.

  The vibration device 40 vibrates the nut member 20 in the feed screw device 1 and includes a piezoelectric element 41 and an amplifier 42. The piezoelectric element 41 is an element that vibrates by an applied voltage, and corresponds to a “vibration generating member” of the present invention. The piezoelectric element 41 is connected to a control device (not shown) via an amplifier 42, and vibrates with a predetermined amplitude and frequency by a signal voltage applied by the control device.

  A plurality of piezoelectric elements 41 are arranged in the circumferential direction in the gap between the first nut body 21 and the second nut body 22 of the nut member 20, and are fixed so as to be sandwiched between the members 21 and 22 by the connecting portion 23. Yes. As described above, the piezoelectric element 41 as the vibration generating member is configured to be interposed and fixed between the thread grooves (the respective female screws 21 a and 22 a) of the nut member 20.

(Operation and effect of the feed screw device 1)
According to the feed screw device 1 described above, the shaft member 10 is rotated by a predetermined rotation amount by the driving device 30, and the nut member 20 that meshes with the shaft member 10 is moved in the axial direction. Thereby, the movable body 2 installed on the nut member 20 is positioned at a predetermined axial position. Further, in the shaft member 10 and the nut member 20 of the feed screw device 1, a frictional force is generated in the meshed male screw 11 and female screws 21a and 22a.

  Therefore, the feed screw device 1 attempts to reduce the frictional force by vibrating the screw grooves (internal threads 21a and 22a) of the nut member 20 with the vibration device 40. The feed screw device 1 according to the present embodiment fixes the piezoelectric element 41 that is a vibration generating member to the nut member 20. Further, the screw groove of the nut member 20 is constituted by the female screw 21a and the female screw 22a which are separated in the axial direction, and the piezoelectric element 41 is interposed and fixed therebetween.

  In such a configuration, when the vibration device 40 applies a signal voltage to the piezoelectric element 41 via the amplifier 42, the first nut body 21 and the second nut body 22 to which the piezoelectric element 41 is fixed vibrate relatively. . Although influenced by the meshing force of the shaft member 10 with the male screw 11 and the reaction force received from the moving body 2, one of the first nut body 21 and the second nut body 22 serves as a reference and the other vibrates. is assumed. In any case, at least one of the female screws 21a and 22a constituting the thread groove of the nut member 20 can be vibrated by vibrating at least one of them. Thereby, the frictional force which generate | occur | produces in the thread groove (male thread 11) of the shaft member 10 and the thread groove of the nut member 20 can be reduced.

  Further, in the feed screw device 1, the piezoelectric element 41 is interposed between the female screw 21a and the female screw 22a which are separated in the axial direction. Thereby, the piezoelectric element 41 is located inside the axial direction range L2 in which the male screw 11 and the female screws 21a and 22a mesh. Therefore, since vibration is efficiently transmitted from the piezoelectric element 41 to the female screws 21a and 22a corresponding to the screw groove portions of the nut member 20, the frictional force generated in the screw grooves can be reliably reduced.

  Further, the nut member 20 to which the piezoelectric element 41 is fixed is configured by integrally connecting a plurality of first nut bodies 21 and second nut bodies 22 formed separately from each other by a connecting portion 23. Accordingly, one of the first nut body 21 provided with the female screw 21 a and the second nut body 22 provided with the female screw 22 a serves as a reference, and the other can be vibrated by the piezoelectric element 41. Therefore, it is possible to reliably vibrate the thread groove portion of the nut member 20 and reduce the frictional force.

  Here, in the present embodiment, the feed screw device 1 is configured to position the moving body 2 by the linear movement of the nut member 20 relative to the shaft member 10. In this case, generally, the axial length L1 of the male screw 11 of the shaft member 10 is often longer than the axial length L2 of the screw groove (female screw 21a, 22a) of the nut member 20 depending on the application. Therefore, by forming the screw groove of the nut member 20 with the female screw 21a and the female screw 22a spaced apart in the axial direction, the piezoelectric element 41 interposed therebetween is always positioned in the vicinity of the female screws 21a and 22a to be vibrated. As a result, vibration can be efficiently performed.

<Second embodiment>
The feed screw device 101 of this embodiment will be described with reference to FIG. The feed screw device 101 in this embodiment is mainly different from the first embodiment in the configuration of the nut member. Since other common configurations are substantially the same as those in the first embodiment, detailed description thereof is omitted. Only the differences will be described below.

  The feed screw device 101 includes a shaft member 10, a nut member 120, a drive device 30, and a vibration device 40. As shown in FIG. 3, the nut member 120 has a plurality of female screws 124 a to 124 c and a plurality of recesses 125 a and 125 b. Unlike the nut member 20 of the first embodiment, the nut member 120 is formed as an integral member. The nut member 120 has an annular shape, and a plurality of female screws 124a to 124c that are thread grooves on the inner peripheral surface are provided at different axial positions. The plurality of female screws 124 a to 124 c mesh with the male screw 11 formed on the outer peripheral surface of the shaft member 10. Each of the female screws 124 a to 124 c corresponds to a plurality of screw groove portions provided in the nut member 120.

  In addition, the nut member 120 has a plurality of recesses 125a and 125b formed over the entire circumference on the inner circumferential surface between the female screws 124a to 124c. Thereby, each internal thread 124a-124c is spaced apart in the axial direction by an amount corresponding to the axial width of the recesses 125a, 125b. In addition, each of the recesses 125 a and 125 b is designed to have a predetermined distance from the bottom surface to the outer peripheral surface of the nut member 120. Thereby, while being able to transmit the rotational driving force between each site | part in which each internal thread 124a-124c was provided, the relative movement of a minute axial direction is permitted.

  And the feed screw apparatus 101 has arrange | positioned the piezoelectric element 41 of the vibration exciting apparatus 40 in several recessed part 125a, 125b, respectively. As a result, in the feed screw device 101, the piezoelectric element 41 fixed to the nut member 120 propagates a predetermined vibration to the thread grooves (female screws 124a to 124c) of the nut member 120 by the signal voltage applied by the control device. It is configured to vibrate. According to the feed screw device 101 having such a configuration, the same effects as those of the first embodiment can be obtained.

  In the present embodiment, the piezoelectric element 41 is disposed in each of the recesses 125a and 125b formed at different axial positions. This is in consideration of the axial length of the nut member 120 set as appropriate according to the application and the excitation capability of the piezoelectric element 41, and the piezoelectric element 41 may be arranged at different axial positions. .

<Third embodiment>
The feed screw device 201 of this embodiment will be described with reference to FIG. The feed screw device 201 in the present embodiment is mainly different from the first embodiment in the members arranged for the vibration generating member, and accordingly, the configurations of the shaft member and the nut member are different. Since other common configurations are substantially the same as those in the first embodiment, detailed description thereof is omitted. Only the differences will be described below.

  The feed screw device 201 includes a shaft member 210, a nut member 220, a drive device 30, and a vibration device 40. As shown in FIG. 4, the shaft member 210 includes a first shaft main body 212, a second shaft main body 213, and a connecting portion 214. The first shaft body 212 is provided with a male screw 212a which is a thread groove on the outer peripheral surface. Similarly to the first shaft main body 212, the second shaft main body 213 is provided with a male screw 213a that is a thread groove on the outer peripheral surface. The first shaft main body 212 and the second shaft main body 213 are members formed separately, and are spaced apart in the axial direction of the feed screw device 201.

  Each male screw 212a, 213a meshes with a female screw 220a of a nut member 220 described later. The first shaft main body 212 and the second shaft main body 213 having such a configuration correspond to the “thread groove main body” of the present invention. And the thread groove of the shaft member 210 is comprised by each male screw 212a, 213a which is the some thread groove part spaced apart in the axial direction.

  The connecting portion 214 is a member that integrally connects the first shaft main body 212 and the second shaft main body 213 corresponding to a plurality of thread groove main bodies. In the present embodiment, the two members are connected by being press-fitted into press-fitting holes provided in the opposing end surfaces of the first shaft main body 212 and the second shaft main body 213. A plurality of connecting portions 214 are provided at equal intervals in the circumferential direction of the first shaft main body 212 and the second shaft main body 213 each having a cylindrical shape. The connecting portion 214 restricts the relative movement of the second shaft main body 213 in the circumferential direction with respect to the first shaft main body 212 so as to be able to transmit the rotational driving force, and allows a minute relative movement in the axial direction. .

  The nut member 220 has an annular shape and is provided with a female screw 220a which is a thread groove on the inner peripheral surface. The female screw 220a meshes with the male screw 212a of the first shaft body 212 and the male screw 213a of the second shaft body 213. As the shaft member 210 rotates, the nut member 220 having such a configuration moves in the axial direction together with the moving body 2 installed on the nut member 220 according to the amount of rotation.

  In the present embodiment, the nut member 220 has a movable range in the axial direction in which the female screw 220a always meshes with the male screw 212a and the male screw 213a of the shaft member 210. That is, the movable range of the nut member 220 is a distance obtained by subtracting the axial distance L4 between the first shaft main body 212 and the second shaft main body 213 from the axial length L3 of the female screw 220a of the nut member 220. As described above, the screw groove of the shaft member 210 is formed by a plurality of screw groove portions (male screws 212a and 213a) that are provided apart in the axial direction in the axial range L3 that meshes with the screw groove (female screw 220a) of the nut member 220. It will be configured.

  In the feed screw device 201, the piezoelectric element 41 of the vibration device 40 is disposed between the first shaft main body 212 and the second shaft main body 213. As a result, the feed screw device 201 causes the piezoelectric element 41 fixed to the shaft member 210 to propagate a predetermined vibration to the thread grooves (male screws 212a and 213a) of the shaft member 210 by the signal voltage applied by the control device. It is configured to vibrate. According to the feed screw device 201 having such a configuration, the same effects as in the first embodiment can be obtained.

<Modification of Embodiment>
In the embodiments (first embodiment to third embodiment), the piezoelectric element 41 has been described as an example of the vibration generating member. On the other hand, as long as the vibration generating member can vibrate the screw groove of the shaft member or the screw groove of the nut member, the vibration generating member can be applied to other than the vibrator using the piezoelectric effect. In the embodiment, the feed screw devices 1, 101, 201 are configured to rotate the shaft member to linearly move the nut member. On the other hand, the feed screw device may cause the shaft member to linearly move by rotating the nut member by the driving device.

  Further, the configuration in which the screw groove of the shaft member and the screw groove of the nut member are directly engaged with each other has been described as an example. On the other hand, the feed screw device may be a ball screw device in which screw grooves respectively formed in the shaft member and the nut member are indirectly meshed via a plurality of balls. In this case, the raceway groove of the ball formed on the outer peripheral surface of the shaft member corresponds to a thread groove, and a male screw is formed by the raceway groove and the ball. In any configuration, the same effect can be obtained by applying the present invention.

1, 101, 201: Feed screw device, 2: Moving body 10, 210: Shaft member, 11: Male screw (thread groove)
212: First shaft body (thread groove body), 213: Second shaft body (screw groove body)
212a, 213a (screw groove portion, screw groove), 214: connecting portion 20, 120, 220: nut member, 21: first nut body (screw groove portion body)
22: Second nut body (screw groove body)
21a, 22a, 220a: female screw (screw groove portion, screw groove), 23: connecting portion 124a to 124c: female screw, 125a, 125b: concave portion 30: drive device, 31: motor, 32: coupling 40: vibration device, 41 : Piezoelectric element (vibration generating member), 42: Amplifier

Claims (3)

A shaft member having a thread groove formed on the outer peripheral surface;
A nut member having a thread groove that meshes with the thread groove of the shaft member on an inner peripheral surface;
A vibration generating member that is fixed to one of the shaft member and the nut member and vibrates the thread groove of the one member;
The screw groove of the one member is constituted by a plurality of screw groove portions provided apart in the axial direction in an axial range meshing with the screw groove of the other member of the shaft member and the nut member,
The vibration generating member is interposed and fixed between the plurality of screw groove portions, and relatively vibrates the plurality of screw groove portions when the nut member is moved relative to the shaft member in the axial direction. The feed screw device that vibrates the thread groove of the one member that is controlled relative to the other member and moves relative to the other member . In claim 1,
It said one member, possess a plurality of threaded portion body is provided with a plurality of said thread groove is formed separately, and a connecting portion integrally connecting a plurality of the thread groove body, and
The vibration generating member is a feed screw device that is a piezoelectric element that vibrates when a signal voltage is applied thereto . In claim 1 or 2,
A feed screw device using the nut member as the one member when the axial length of the screw groove of the shaft member is longer than the axial length of the screw groove of the nut member.

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