JP2013200032A - Ball screw device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ball screw device having no restriction on a mounting position of a sensor that suitably monitors vibrations or collision force to be induced when a rolling element collides with a circulating part.SOLUTION: A ball screw device 1 includes: a screw shaft 10 having a screw groove 10a; a nut 20 having a screw groove 20a; a plurality of balls 30 disposed in a load rolling path 40 formed by both screw grooves 10a, 20a; and a return tube 50 for feeding the balls 30 from an end point to a start point of the load rolling path 40 to circulate the balls 30. An end of the return tube 50 is provided with a tongue part 51 that scoops up the balls 30 in the load rolling path 40 and guides the balls 30 to the return tube 50. The tongue part 51 is provided with a strain gauge 60.

Description

  The present invention relates to a ball screw device used for a machine tool, an injection molding machine, a semiconductor manufacturing apparatus, and the like.

  Conventionally, a ball screw device has a spiral shaft formed by a screw shaft having a helical thread groove on the outer peripheral surface, a nut having a screw groove facing the screw groove of the screw shaft on the inner peripheral surface, and both screw grooves. And a plurality of balls (rolling elements) loaded in a freely rolling manner in the load rolling path. Then, when the nut and the screw shaft that are screwed to the screw shaft through the ball are relatively rotated, the screw shaft and the nut are relatively moved in the axial direction through the rolling of the ball. .

Such a ball screw device is provided with a ball circulation path that forms an endless ball path by communicating the starting point and the end point of the load rolling path. That is, when the ball moves around the screw shaft while moving in the load rolling path and reaches the end point of the load rolling path, the ball is scooped up from one end of the ball circulation path and passes through the ball circulation path. The other end of the ball circulation path is returned to the starting point of the load rolling path.
As described above, since the ball rolling in the load rolling path is circulated infinitely by the ball circulation path, the screw shaft and the nut can continuously move relative to each other. As a ball circulation type using a ball circulation path, there are a tube type, a top type, an end cap type, an end deflector type, and the like.

  In such a ball screw device, abnormalities such as seizure, wear, and damage may occur. However, a ball screw device including an abnormality detection device that detects the abnormality is known. For example, Patent Document 1 discloses a ball screw device in which a vibration sensor (accelerometer) is attached to a return tube. Since the vibration of the return tube can be detected by the vibration sensor, the abnormality of the ball screw device can be detected by the vibration generated due to seizure, wear, breakage or the like of the screw shaft, nut, or ball.

JP 2001-349407 A

However, in the technique described in Patent Document 1, since a vibration sensor (accelerometer) is used as a sensor, the sensor itself has a certain size (volume), and a space for providing the sensor is provided as a ball screw device. Needed to be formed. Therefore, the ball screw device is often increased in size by attaching a vibration sensor.
Therefore, there is room for improvement in a ball screw device in which there is no restriction on the mounting position of a sensor that preferably monitors vibrations and collision force generated when a rolling element collides with a circulating component such as a return tube.
Therefore, the present invention has been made paying attention to the above-mentioned problems, and its purpose is to restrict the mounting position of a sensor that suitably monitors vibrations and collision forces generated when a rolling element collides with a circulating component. It is an object of the present invention to provide a ball screw device that does not have any.

The invention according to claim 1 for achieving the above object has a screw shaft having a helical thread groove on the outer peripheral surface and a screw groove facing the screw groove of the screw shaft on the inner peripheral surface. A nut screwed to the screw shaft via a plurality of balls that are movably loaded in a spiral load rolling path formed by a thread groove, and the ball from the end point of the load rolling path In a ball screw device comprising: a ball circulation path that circulates and sends the ball to
A strain gauge is provided in the ball circulation path.
By setting it as such a structure, since the strain gauge is thin-film-like and small, the space which arrange | positions a detection part can be made smaller.

According to a second aspect of the present invention, in the ball screw device according to the first aspect, the ball circulation path changes the traveling direction of the ball and scoops up the ball from the end point of the ball circulation path. A raising portion, and a curved portion for guiding the ball scooped up by the ball scooping portion to an end portion of the ball circulation path,
The strain gauge is provided in the ball scooping part or the curved part, or in the vicinity thereof.

Here, in the case where the circulation component is employed as the ball circulation path, the ball scooping portion indicates an inlet portion when the ball is inserted into the circulation component. Further, as the vicinity thereof, the strain gauge may be provided at a tongue portion that scoops up the ball in the load rolling path and guides it to the circulating component at an end portion of the circulating component.
By adopting such a configuration, a strain gauge is installed in a curved part (curved part) or a ball scooping part (tang part) with high detection accuracy of vibration and collision force, so vibration and collision force are high. It can be detected with accuracy.

Further, the invention according to claim 3 is the ball screw device according to claim 1 or 2, wherein the ball circulation path is attached to a through hole that penetrates the inside of the nut in an axial direction and an end of the nut. An end cap in which a communication path for communicating between the load rolling path and the through hole is formed, and a tangential scooping system comprising two synthetic resin divided bodies divided along the rolling direction of the ball It is characterized by being at least one of a circulating part, an end deflector, and a circulating top.
Here, when an end cap is adopted as the ball circulation path, it is preferable that the strain gauge is attached to a portion adjacent to the bending portion (curved portion) of the communication passage.

  The end deflector scoops up the ball from the end point of the load rolling path and guides it to the end of the ball circulation path. The end deflector protrudes into the load rolling path and changes the traveling direction of the ball to scoop up the ball from the end point of the load rolling path, and the ball scooped up by the tongue section And a curved guide path that guides the ball to the end of the ball circulation path. The strain gauge is joined to the surface of the end deflector, and the surface of the end deflector to which the strain gauge is joined is a portion located near the surface of the tongue portion or the curved portion of the guide path. It is preferable that

In addition, when the circulation top is adopted as the ball circulation path, it is preferable that a strain gauge is provided on the surface of the circulation top corresponding to the back side of the ball return groove.
In addition, when the circulating top is employed as the ball circulation path, the strain gauge is preferably provided in the vicinity of the ball scooping portion at both ends in the longitudinal direction of the ball return groove.
The invention according to claim 4 is the ball screw device according to any one of claims 1 to 3, wherein the strain gauge is provided in the ball circulation path.
Here, in the case where an end cap is adopted as the ball circulation path, the strain gauge is used as the ball scooping portion loosely fitted in the rolling element passage at a communication portion between the communication path and the rolling element passage. It is preferable to be embedded in the tongue portion or in the adjacent portion of the tongue portion.

When the strain gauge is embedded in the end deflector, the end deflector protrudes into the load rolling path and changes the traveling direction of the ball to move the ball from the end point of the load rolling path. A tongue portion that scoops up and a curved guide path that guides the ball scooped up by the tongue portion to an end portion of the ball circulation path, and the strain gauge includes the tongue portion and the tongue portion. It is preferable that it is embedded in the vicinity part or the part located in the vicinity of the curved part of the guide path.
By setting it as such a structure, the strain gauge can be provided in the said ball circulation path, and it can integrate with the said ball circulation path, and the attachment time of the detection part to the said ball circulation path can be reduced.

The invention according to claim 5 is characterized in that in the ball screw device according to any one of claims 1 to 4, a groove portion into which the lead wire of the strain gauge is inserted is provided in the nut.
The invention according to claim 6 is characterized in that, in the ball screw device according to any one of claims 1 to 5, the lead wire of the strain gauge is fixed or joined to the ball circulation path.
Here, when an end cap is employed as the ball circulation path, it is preferable that a lead wire to which a detection signal of the strain gauge is output is fixed to the end cap.

Further, when the end deflector is employed as the ball circulation path, the strain gauge includes a main body portion for detecting strain and a lead wire as a lead wire, and the main body portion and the lead wire It is more preferable that the covering portion in which the metal wire is covered with the covering member is bonded to the surface of the end deflector.
Furthermore, it is more preferable that at least one of the main body portion and the covering portion is bonded to the surface of the end deflector with an adhesive.
By setting it as such a structure, since the strain gauge and the lead wire are integrally fixed to the said ball circulation path, it can prevent that a lead wire breaks with respect to a strain gauge.

The invention according to claim 7 is the ball screw device according to any one of claims 1 to 6, wherein the strain gauge is fixed to the ball circulation path by an adhesive.
Here, it is preferable that only the main body portion of the strain gauge is fixed, and not only the main body portion but also the lead wire is fixed to the ball circulation path by an adhesive.
In addition, when the circulation top is adopted as the ball circulation path, it is preferable that the strain gauge and the lead wire covering portion are fixed to the circulation top by an adhesive.
In addition, when the circulation top is adopted as the ball circulation path, it is preferable that a part of the lead wire covering portion of the strain gauge is fixed to the circulation top.

  According to the present invention, since a strain gauge is used as a sensor, there is provided a ball screw device in which there is no restriction on the mounting position of the sensor for preferably monitoring vibration and collision force generated when a rolling element collides with a circulating component. can do.

It is sectional drawing which follows the axial direction which shows the structure in 1st Embodiment of the ball screw apparatus which concerns on this invention. It is sectional drawing which follows the 2-2 line of FIG. It is a fragmentary sectional view which follows the axial direction which shows the structure in 1st Embodiment of the ball screw apparatus which concerns on this invention. It is a figure which shows the circuit structure of the strain gauge in 1st Embodiment of the ball screw apparatus which concerns on this invention. It is sectional drawing which follows the surface orthogonal to the axial direction which shows the structure in 2nd Embodiment of the ball screw apparatus which concerns on this invention. It is a fragmentary sectional view which follows the axial direction which shows the structure in 2nd Embodiment of the ball screw apparatus which concerns on this invention. It is a front view which shows the structural example of the ball screw apparatus of 3rd Embodiment. It is a figure which shows the surface side shape seen from the axial end side of the screw shaft of the end cap in 3rd Embodiment. It is a figure which shows the back surface side shape of the end cap in 3rd Embodiment. It is a side view which shows the end cap in 3rd Embodiment. It is a front view which shows the structural example of the ball screw apparatus of 4th Embodiment. It is a figure which shows the surface side shape seen from the axial end side of the screw shaft of the end cap in 4th Embodiment. It is a figure which shows the back surface side shape of the end cap in 4th Embodiment. It is a side view which shows the end cap in 4th Embodiment. It is a front view which shows the structural example of the ball screw apparatus of 5th Embodiment. It is a figure which shows the surface side shape seen from the axial end side of the screw shaft of the end cap in 5th Embodiment. It is a figure which shows the back surface side shape of the end cap in 5th Embodiment. It is sectional drawing which follows the axial direction which shows the structure in 6th Embodiment of a ball screw apparatus. It is a perspective view which shows the structure of the circulation component in 6th Embodiment of a ball screw apparatus. It is a front view which shows the structure of the division | segmentation body of the circulation components in 6th Embodiment of a ball screw apparatus. It is a figure which shows the structure in 6th Embodiment of a ball screw apparatus, (a) is sectional drawing which follows the 21-21 line of FIG. 18, (b) is a perspective view which shows the installation position of the strain sensor in a circulation component. is there. It is a figure which shows the structure in 7th Embodiment of a ball screw apparatus, (a) is sectional drawing which follows the surface orthogonal to an axial direction, (b) is a top view of the division body of a circulation component, (c) is a circulation. It is a perspective view which shows the installation position of the strain sensor in components. It is a figure which shows the structure in 8th Embodiment of a ball screw apparatus, (a) is sectional drawing which follows the surface orthogonal to an axial direction, (b) is a perspective view which shows the installation position of the strain sensor in a circulation component. . It is a figure which shows the structure in 9th Embodiment of a ball screw apparatus, (a) is sectional drawing which follows the surface orthogonal to an axial direction, (b) is a perspective view which shows the installation position of the strain sensor in a circulation component. . It is sectional drawing explaining 10th Embodiment of a ball screw apparatus. FIG. 26 is a front view of the ball screw device of FIG. 25. It is a figure explaining the end deflector of the ball screw apparatus of FIG. 25, and the strain gauge joined to the surface of this end deflector. It is sectional drawing explaining 11th Embodiment of a ball screw apparatus. FIG. 29 is a front view of the ball screw device of FIG. 28. It is a figure explaining the end deflector of the ball screw apparatus of FIG. 28, and the strain gauge joined to the surface of this end deflector. It is sectional drawing explaining 12th Embodiment of a ball screw apparatus. FIG. 32 is a front view of the ball screw device of FIG. 31. It is a figure explaining the end deflector of the ball screw apparatus of FIG. 31, and the strain gauge embedded in the part located in the vicinity of the curved part of the guide path of this end deflector. It is a figure explaining the end deflector of the ball screw apparatus of FIG. 31, and the strain gauge embedded in the tongue part of this end deflector. It is a figure which shows the structure in 13th Embodiment of a ball screw apparatus, (a) is a perspective view, (b) is a fragmentary sectional view in alignment with the axial direction of a nut. It is a figure which shows the structure of the circulation top in 13th Embodiment of a ball screw apparatus, (a) is a perspective view, (b) is a top view, (c) is a side view, (d) is a rear view. It is a fragmentary sectional view in alignment with the direction orthogonal to the axial direction in 13th Embodiment of a ball screw apparatus. It is a figure which shows the structure of the circulation top in 13th Embodiment of a ball screw apparatus, (a) is a rear view, (b) is a side view. It is a fragmentary sectional view in alignment with the direction orthogonal to the axial direction in 14th Embodiment of a ball screw apparatus. It is a figure which shows the structure of the circulation top in 14th Embodiment of a ball screw apparatus, (a) is a top view, (b) is a side view.

Embodiments of a ball screw device according to the present invention will be described below with reference to the drawings.
(First embodiment)
FIG. 1 is a cross-sectional view along the axial direction showing the configuration of the ball screw device according to the first embodiment of the present invention. 2 is a cross-sectional view taken along line 2-2 in FIG. FIG. 3 is a partial cross-sectional view along the axial direction showing the configuration of the ball screw device according to the first embodiment of the present invention. FIG. 4 is a diagram showing a circuit configuration of a strain gauge in the first embodiment of the ball screw device according to the present invention. However, in FIG. 3, the return tube is also shown broken.

<Configuration of ball screw device>
As shown in FIG. 1, the ball screw device 1 according to the present embodiment includes a screw shaft 10 in which a spiral groove 10a is formed on the outer peripheral surface, and a spiral groove 20a on the inner peripheral surface. And a cylindrical nut 20 formed.
The screw shaft 10 is inserted through the nut 20, the screw groove 10a of the screw shaft 10 and the screw groove 20a of the nut 20 face each other, and a spiral load rolling path is formed by the space between the screw grooves 10a and 20a. 40 is formed. A plurality of balls (rolling elements) 30 are slidably loaded in the load rolling path 40, and the nut 20 is screwed onto the screw shaft 10 via the balls 30.

<Return tube>
A part of the outer surface of the nut 20 is cut flat, and a return tube 50 bent in a substantially U shape is fixed on a plane parallel to the axial direction. This return tube 50 corresponds to a ball circulation path. That is, the nut 20 is provided with a pair of through holes 21, 21 that open in this plane and communicate with the thread groove 20 a of the nut 20, and both ends of the return tube 50 are connected to the through holes 21, 21. It is inserted from the plane side. And the center part of the return tube 50 located outside the through-holes 21 and 21 is distribute | arranged on the said plane. Two or more return tubes may be attached to one nut, and in that case, two or more pairs of through holes are provided.

  The ball 30 rolling in the load rolling path 40 is circulated through the return tube 50. That is, the ball 30 moves around the screw shaft 10 while moving in the load rolling path 40 to reach the end point of the load rolling path 40 (intersection of the return tube 50 and the load rolling path 40). The return tube 50 is lifted into the return tube 50 from one end (opening).

  Here, as shown in FIG. 2, a tongue 51 is provided at the end of the return tube 50. When the ball 30 collides with the tongue 51, the ball 30 is scooped up from the load rolling path 40 and guided into the return tube 50 along the tongue 51. The scooped up ball 30 passes through the return tube 50 to the other end (opening) of the return tube 50 and is guided by a tongue 51 provided at the end to load from the return tube 50. The starting point of the rolling path 40 is returned.

  As described above, the ball 30 that rolls in the load rolling path 40 is circulated indefinitely by the return tube 50 that communicates the starting point and the end point of the load rolling path 40, so that the screw shaft 10 When the nut 20 and the nut 20 are rotated relative to each other, the screw shaft 10 and the nut 20 continuously move relative to each other in the axial direction via the rolling of the ball 30. A separator made of resin or elastomer may be interposed between the adjacent balls 30 and 30. Further, a spacer ball made of resin or metal smaller than the ball receiving the load may be interposed. Further, the cross-sectional shape of the thread grooves 10a, 20a may be an arc shape or a gothic arc shape.

<Strain gauge>
In the ball screw device of the present embodiment, as shown in FIGS. 2 and 3, a strain gauge 60 as a sensor is installed in the tongue portion 51.
The strain gauge 60 is connected to the detection unit 61 that detects vibration and collision force during operation of the ball screw device, and transmits the detected vibration and collision force during operation of the ball screw device as a signal. Lead wire 62. The strain gauge 60 is fixed to the tongue portion 51 by joining the detection portion 61 to the tongue portion 51 of the circulation tube 50 with an adhesive or the like.
Thus, the reason why the strain gauge 60 is installed in the tongue 51 is that it is suitable for monitoring the vibration of the ball screw device because the ball frequently collides with the tongue. That is, this installation location is suitable for obtaining information for monitoring the degree of fatigue of the tongue 51 due to the collision force of the ball 30 applied to the tongue 51 and the repeated load.

  Further, an excessive load (due to the collision force of the ball 30) or breakage of the tongue 51 due to fatigue failure can be detected in advance and used for prevention. Since the tongue 51 is an important part for guiding the ball 30 into the circulation tube 50, detecting the collision force applied to this part is extremely important for grasping the state of the ball screw device 1. is important. In particular, if the tongue 51 is broken, the ball 30 cannot be circulated and the ball screw device may be locked (become non-rotatable). Therefore, detection of the state of the tongue 51 is extremely important.

  On the other hand, the through hole 21 of the nut 20 is provided with a groove portion 22 into which the lead wire 62 is inserted in order to guide the lead wire 62 connected to the detection portion 61 of the strain gauge 60 to the outside. Along with the installation in the groove portion 22, the lead wire 62 is covered with the covered wire 63 in the portion exposed to the outside from the groove portion 22. On the other hand, the portion where the lead wire 62 is fitted into the groove portion 22 (the portion from the portion covered by the covered wire 63 (the surface of the nut 20) to the portion connected to the detecting portion 61) is provided with an electrical insulating coating. ing.

Here, as shown in FIGS. 4A and 4B, the strain gauge 60 is connected by a one-gauge method in which a strain gauge 60 is provided on one side of the bridge circuit and a fixed resistor is connected to the other three sides. I do not care. However, since the temperature change is expected to be large, the “1-gauge 3-wire system” shown in FIG. 4B is desirable instead of the “1-gauge 2-wire system” shown in FIG. 4A and 4B show R: fixed resistance, Rg: gauge resistance, E: bridge voltage, E ₀ : output voltage.

  In this manner, by applying an electrical insulating coating to the lead wire 62 in the section from the detection unit 61 to the covering unit 63, even when the circulation tube 50 is made of metal, the electrical circuit of the strain gauge 60 (detection unit 61) is short-circuited. Without this, the lead wire 62 can be joined to the circulation tube 50. Moreover, since the groove part 22 can be made shallow compared with wiring to the said area | region with the coating | coated part 63 with a large cross-sectional area, the processing time of the groove part 22 in the nut 20 can be shortened.

Note that a part of the covered wire 63 is also preferably joined to the circulation tube 50. By doing so, even when the lead wire 62 is pulled, no force is directly applied to the lead wire 62 itself, so that disconnection of the lead wire 62 can be prevented.
Note that the strain gauge 60 can withstand the use environment without interfering with the operation of the ball screw device used in the present embodiment, and can detect necessary information such as vibration and collision force during operation of the ball screw device. There is no restriction | limiting in particular, According to the objective, it selects suitably. As such a strain gauge 60, a strain gauge for general stress measurement capable of measuring (detecting) up to a maximum elongation of about 5% can be mentioned. For example, a KFG type strain gauge manufactured by Kyowa Denki Co., Ltd. can be mentioned.

Since the detector 61 of the strain gauge 60 is generally thin and small in size, it requires almost no space for installing the sensor, and there are no strict restrictions on the mounting position. Compactness can be achieved.
In addition, by using the strain gauge 60 of the present embodiment, the strain gauge 60 as a sensor can be easily installed at a site that is difficult to install with a vibration sensor, so that vibration and collision force can be detected effectively. .

(Second Embodiment)
Next, a second embodiment of the ball screw device according to the present invention will be described with reference to the drawings. Note that the present embodiment is different from the first embodiment described above only in the installation mode of the strain gauge, and therefore, the description of the same configuration given the same reference numeral as the above-described embodiment is omitted. FIG. 5 is a front view showing the configuration of the ball screw device according to the second embodiment of the present invention. FIG. 6 is a right side view showing the configuration of the ball screw device according to the second embodiment of the present invention.

  As shown in FIGS. 5 and 6, in the ball screw device of the present embodiment, a strain gauge 60 as a sensor is installed in the bent portion 50 a of the circulation tube 50. The strain gauge 60 is joined to the bent portion 50a of the circulation tube 50 with an adhesive or the like. Here, the bent portion 50a is an outer peripheral surface corresponding to a place where the movement direction of the ball 30 changes in the circulation tube 50, that is, an inflection point portion in the trajectory of the ball 30 in the U-shaped circulation tube 50, and The outer peripheral surface of the circulation tube 50 corresponding to the vicinity thereof is indicated.

Since the bent portion 50a of the circulation tube 50 is a portion where the ball collides and the movement direction of the ball changes, by installing a strain gauge 60 on the bent portion 50a, the vibration of the ball screw device is preferably monitored. be able to. In particular, this installation location is suitable for obtaining information for monitoring the collision force of the ball 30 applied to the bent portion 50a and the force by which the circulation tube 50 is pushed up as the ball 30 circulates.
Therefore, it is possible to detect in advance a pressing component (not shown) for fixing the circulation tube 50 to the nut 20 or damage to the circulation tube 50 due to an excessive collision force by the ball 30 or an excessive pushing force against the circulation tube 50.

Further, in the present embodiment, unlike the first embodiment described above, it is not necessary to form the groove 22 or the like for wiring the lead wire on the nut 20, and the manufacturing efficiency is high.
Furthermore, in this embodiment, a part of the lead wire covering portion 63 is also joined to the circulation tube 50. As a result, even when the lead wire 62 is pulled, no force is directly applied to the lead wire 62 itself, so that the disconnection of the lead wire 62 can be prevented.
The ball screw device according to the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

(Third embodiment)
Next, a third embodiment will be described.
The third embodiment is a ball screw device to which the present invention is applied.
(Constitution)
FIG. 7 is a front view illustrating a configuration example of the ball screw device 101 according to the third embodiment.
As shown in FIG. 7, the ball screw device 101 is a ball screw device having an end cap type circulation path.
The ball screw device 101 includes a screw shaft 110 as a guide element, a nut 120 as a moving body, end caps 131 and 132, and a ball 140.
The screw shaft 110 is a substantially cylindrical rod-like body, and a female screw (spiral) ball screw device groove 111 is formed on the outer peripheral surface.

  The nut 120 has a substantially cylindrical shape, and a female screw (spiral) ball screw device groove (not shown) is formed on the inner peripheral surface at a position facing the ball screw device groove 111 of the screw shaft 110 in the radial direction. ing. The ball screw device groove of the nut 120 and the ball screw device groove 111 of the screw shaft 110 form a spiral rolling element passage where the ball 140 rolls. Further, the nut 120 is formed with a through hole 121 penetrating in the axial direction inside. End caps 131 and 132 are attached to both ends of the nut 120 in the axial direction.

  Each of the end caps 131 and 132 has a substantially cylindrical shape having an outer diameter equal to the outer diameter of the axial end portion of the nut 120, and is formed with rolling element circulation grooves 131a and 132a. For example, the end caps 131 and 132 are formed of a resin or a metal material. Here, the rolling element circulation grooves 131a and 132a circulate the ball 140 between the through hole 121 of the nut 120 and the spiral rolling element passage. Therefore, one end of each rolling element circulation groove 131a, 132a communicates with the through-hole 121 opened at the end of the nut 120, and the other end communicates with the spiral rolling element passage. The end caps 131 and 132 are formed with tongue portions 131b and 132b that are loosely fitted in the spiral rolling element passage and are formed at the communicating portions between the rolling element circulation grooves 131a and 132a and the spiral rolling element passage. ing. The rolling element circulation grooves 131a and 132a scoop up the ball 140 in the spiral rolling element passage by the tongue portions 131b and 132b and transfer the ball 140 to and from the spiral rolling element passage.

A plurality of vibration sensors 151, 152, 153, and 154 for determining an abnormality (for determining a vibration state) of the ball screw device 101 are attached to the end caps 131 and 132.
8 to 10 are views showing the end caps 132 and 132. FIG. 8 is a view showing the shape of the surface side of the end caps 131 and 132 as seen from the shaft end side of the screw shaft 110. FIG. 9 is a diagram showing the shape of the back surface side of the end caps 131 and 132 that are attached to the nut 120. FIG. 10 is a side view of the end caps 131 and 132 as viewed from the direction perpendicular to the axial direction of the screw shaft 110.

In addition to FIG. 7, as shown in FIGS. 8 to 10, in the example of this embodiment, the end caps 131 and 132 have four vibration sensors 151, 152, 153, and 154 on the surfaces 131 c and 132 c. It is attached. In this embodiment, four vibration sensors are attached because of the two-thread screw, but the number of sensors varies depending on the number of ball screws (number of circuits).
The vibration sensors 151, 152, 153, and 154 are configured using a thin general thin strain gauge. That is, the vibration sensors 151, 152, 153, and 154 include a main body (strain gauge part) 161 provided with a resistance wire on a lattice or a resistance foil subjected to photo-etching, and a lead wire that outputs a detection signal of the main body 161. 162. For example, as the main body 161, there is a model KFG series strain gauge provided by Kyowa Denki Co., Ltd.

  As shown in FIG. 7, the vibration sensors 151, 152, 153, and 154 having such a configuration are formed by bending the rolling element circulation grooves 131 a and 132 a formed on the back surfaces 131 d and 132 d of the end caps 131 and 132. The end caps 131 and 132 are respectively attached to the surfaces 131c and 132c so as to be positioned in the vicinity of the portions 131a1 and 132a1. That is, the end sensors 131 are arranged so that the vibration sensors 151, 152, 153, and 154 are located on the back side of the bending portions 131a1 and 132a1 of the rolling element circulation grooves 131a and 132a or adjacent to the bending portions 131a1 and 132a1. , 132.

  For example, as shown in FIGS. 8 to 10, the rolling element circulation grooves 131 a and 132 a extend in the tangential direction of the inner surfaces 131 e and 132 e of the end caps 131 and 132, and the end caps 131 and 132 (or the screw shaft 110). There are bending portions 131a1 and 132a1 that are bent in the axial direction. As shown in FIGS. 8 and 9, the vibration sensors 151 and 154 are arranged along the bending portions 131a1 and 132a1 as seen from the axial direction of the end cap (or screw shaft) and in the example shown in FIG. As described above, the end caps 131 and 132 (or the screw shaft 110) are attached to the front surfaces 131c and 132c of the end caps 131 and 132 so that the axial distance is closer to the bending portions 131a1 and 132a1.

Further, the vibration sensors 151 and 154 (similarly to the vibration sensors 152 and 153) are arranged within the adhesion range of the surfaces 131c and 132c of the end caps 131 and 132 as shown by the hatched area A in FIG. The end portions of the covering portion 162a of 162 are integrated and bonded by an adhesive.
The vibration sensors 151, 152, 153, and 154 output detection signals to an arithmetic unit (not shown) for determining an abnormality of the ball screw device 101 (not shown). The arithmetic device determines whether the ball screw device 101 is abnormal based on detection signals from the vibration sensors 151, 152, 153, and 154.

(Operation, action, etc.)
Next, operation | movement, an effect | action, etc. of the ball screw apparatus 101 are demonstrated.
In the ball screw device 101, the nut 120 is screwed onto the outer periphery of the screw shaft 110 via the plurality of balls 140, and one of the screw shaft 110 and the nut 120 is relatively rotated. Moves linearly relative to the screw shaft 110 in the axial direction. At this time, the plurality of balls 140 is a spiral rolling element formed between the through hole 121 of the nut 120 and the screw shaft 110 and the nut 120 by the rolling element circulation grooves 131 a and 132 a of the end caps 131 and 132. Circulate through the passage.

Then, the abnormality determination arithmetic unit detects the vibration in the ball screw device 101 operating in this way based on the detection values from the vibration sensors 151, 152, 153, and 154, and performs abnormality determination.
In the above description of the embodiment, the ball screw device groove 111 of the screw shaft 110 and the ball screw device groove of the nut 120 constitute, for example, a rolling element rolling groove. Further, the rolling element circulation grooves 131a and 132a constitute, for example, a communication path.

(Effect in the third embodiment)
In the third embodiment, since the main body 161 made of a strain gauge is thin and small and does not require an arrangement space, the ball screw device 101 can be miniaturized while enabling abnormality determination.
Further, since the strain gauges are installed in the adjacent portions of the bending portions 131a1 and 132a1 of the rolling element circulation grooves 131a and 132a with high detection accuracy of vibration and collision force, the vibration sensors 151, 152, 153, and 154 It is possible to detect vibration and collision force generated in the screw device 101 with high accuracy.
In addition, although the strain gauge lead 162 is thin and easy to break, in the third embodiment, the main body 161 and the covering portion 162a of the lead wire 162 are integrally joined to the end caps 131 and 132. It is possible to prevent the lead wire 162 from being disconnected from the 161.

(Fourth embodiment)
Next, a fourth embodiment will be described.
(Constitution)
The fourth embodiment is also a ball screw device 101 to which the present invention is applied. Note that the same reference numerals in the fourth embodiment denote the same components as in the third embodiment.
FIG. 11 is a front view illustrating a configuration example of the ball screw device 101 according to the fourth embodiment. 12-14 is a figure which shows the end caps 131 and 132. FIG.
As shown in FIGS. 11 to 14, in the ball screw device 101 according to the fourth embodiment, the vibration sensors 151, 152, 153, and 154 are arranged so that the rolling element circulation grooves 131 a and 132 a in the end caps 131 and 132 are offset. A main body 161 is embedded in the vicinity (adjacent part) of the curved parts 131a1 and 132a1, and is integrally formed with the end caps 131 and 132.

  That is, for example, the main body 161 of the vibration sensors 151 and 154 is formed in the rolling element circulation grooves 131a and 132a as seen from the axial direction of the end caps 131 and 132 (or the screw shaft 110) as in the example shown in FIGS. The end caps are arranged so that the axial distances of the end caps 131 and 132 (or the screw shaft 110) are close to the bent portions 131a1 and 132a1 along the bent portions 131a1 and 132a1 as in the example shown in FIG. 131 and 132 are embedded.

In the fourth embodiment, the vibration sensors 151 and 154 (similarly to the vibration sensors 152 and 153) are shown as hatched regions B in FIG. 14 while the main body 161 is embedded in the end caps 131 and 132. The end portion of the covering portion 162a of the lead wire 162 is bonded to the bonding range of the surfaces 131c and 132c of the end caps 131 and 132 with an adhesive.
The other configuration of the ball screw device 101 of the fourth embodiment is the same as the configuration of the ball screw device 101 of the third embodiment.

(Effect in 4th Embodiment)
In the fourth embodiment, as in the case of the third embodiment, the main body 161 made of a strain gauge is thin and small, so that no arrangement space is required. The apparatus 101 can be downsized.
Further, since the strain gauge is buried, the strain gauge is accurately installed in the adjacent portion of the bending portions 131a1 and 132a1 of the rolling element circulation grooves 131a and 132a with high detection accuracy of vibration and collision force. , 152, 153, and 154 can detect vibration and collision force generated in the ball screw device 101 with higher accuracy.

Also in the fourth embodiment, the main body 161 of the vibration sensors 151, 152, 153, 154 is embedded in the end caps 131, 132 and the covering portion 162 a of the lead wire 162 is joined to the end caps 131, 132. Therefore, it is possible to prevent the lead wire 162 from being disconnected from the main body portion 161.
In the fourth embodiment, the main body 161 is embedded in the end caps 131 and 132 so as to be integrated with the end caps 131 and 132, so that vibration sensors 151, 152, 153, and 154 for the end caps 131 and 132 are integrated. Installation time can be reduced.

(Fifth embodiment)
Next, a fifth embodiment will be described.
(Constitution)
The fifth embodiment is also a ball screw device 101 to which the present invention is applied. Note that the same reference numerals in the fifth embodiment denote the same components as in the third embodiment.
FIG. 15 is a front view illustrating a configuration example of the ball screw device 101 according to the fifth embodiment. 16 and 17 are diagrams showing the end caps 131 and 132. FIG.
As shown in FIGS. 15 to 17, in the ball screw device 101 of the fifth embodiment, the vibration sensors 151, 152, 153, and 154 that are strain gauges are provided in the tongue portions 131 b and 132 b of the end caps 131 and 132. Alternatively, the main body 161 is embedded in the vicinity (adjacent part) of the tongues 131b and 132b and is integrally formed with the end caps 131 and 132. In the fifth embodiment, the covering portions 162a of the lead wires 162 of the vibration sensors 151, 152, 153, and 154 are portions facing the surfaces 131c and 132c of the end caps 131 and 132 (shaded area C shown in FIG. 16). ) Is adhered to the surfaces 131c and 132c by an adhesive.
The other configuration of the ball screw device 101 of the fifth embodiment is the same as that of the ball screw device 101 of the third embodiment.

(Effect in 5th Embodiment)
In the fifth embodiment as well, in the same way as in the third and fourth embodiments, the main body 161 made of a strain gauge is thin and small, so that no arrangement space is required. The ball screw device 101 can be reduced in size.
Also in the fifth embodiment, the main body 161 of the vibration sensors 151, 152, 153, 154 is embedded in the end caps 131, 132 and the covering portion 162 a of the lead wire 162 is joined to the end caps 131, 132. Therefore, it is possible to prevent the lead wire 162 from being disconnected from the main body portion 161.
In addition, since the strain gauge is a sensor that can be easily installed in places where other sensors such as an acceleration sensor are difficult to install, in the fifth embodiment, the end caps 131 and 132 with high detection accuracy of vibration and collision force are used. The body portion 161 made of a strain gauge can be accurately attached in the tongue portions 131b and 132b or in the vicinity of the tongue portions 131b and 132b.

  Accordingly, in the end caps 131 and 132, the tongue portions 131b and 132b are higher in detection accuracy of vibration and collision force than the curved portions 131a1 and 132a1 of the rolling element circulation grooves 131a and 132a. In the embodiment, the vibration sensors 151, 152, 153, and 154 have the body portion 161 disposed in or near the tongue portions 131b and 132b. It can be detected with higher accuracy. Furthermore, in the fifth embodiment, the states of the tongue portions 131b and 132b can be detected with high accuracy.

As mentioned above, although embodiment of this invention was described, embodiment can be variously changed and improved without being limited to this.
For example, in the present embodiment, only one or five or more vibration sensors may be provided to detect vibration.

(Sixth embodiment)
Next, a ball screw device according to a sixth embodiment of the present invention will be described with reference to the drawings.
FIG. 18 is a cross-sectional view along the axial direction showing the configuration of the ball screw device according to the sixth embodiment. FIG. 19 is a perspective view showing the configuration of the circulating component in the sixth embodiment of the ball screw device. FIG. 20 is a front view showing the configuration of the divided parts of the circulating parts in the sixth embodiment of the ball screw device. FIG. 21 is a diagram showing a configuration of the ball screw device according to the sixth embodiment. FIG. 21A is a cross-sectional view taken along the line 21-21 in FIG. 18, and FIG. It is a perspective view which shows a position. In FIG. 18, a cross section of the nut is shown, the screw shaft is not a cross section, and the circulating component is shown in a cross section along the dividing line.

<Ball screw device>
As shown in FIG. 18, the ball screw device 201 of this embodiment includes a screw shaft 210 having a spiral thread groove 211 formed on the outer peripheral surface and a nut having a spiral thread groove 221 formed on the inner peripheral surface. 220, a ball 230 as a rolling element, a circulation part 240 made of synthetic resin, and an attachment part 250 for fixing the circulation part 240 to the nut 220. The ball 230 is disposed so as to be able to roll between a raceway formed by the thread groove 211 of the screw shaft 210 and the thread groove 221 of the nut 220 and in a ball return path 241 formed by the circulation component 240.
A flat surface 222 for attaching the circulation component 240 is formed on the outer peripheral surface of the nut 220. On the flat surface 222, a pair of through holes (circulation holes) 223 and 223 are formed.

[Circulating parts]
The circulation component 240 has a main body portion 241 and a pair of leg portions 242 and has a U shape. A lower surface (surface sandwiched between the leg portions 242 and 242) 241 b of the main body 241 is a surface that contacts the flat surface 222 of the nut 220. Further, as shown in FIG. 19, the circulating component 240 includes two divided bodies 240 </ b> A and 240 </ b> A that are divided along a line L that indicates the moving direction of the ball 230.

  As shown in FIG. 20, the divided bodies 240 </ b> A and 240 </ b> A of the circulation component 240 include a main body 241 </ b> A and a pair of legs 242 </ b> A, and a groove 245 a corresponding to the ball return path 245 is formed. A tongue 242a for picking up a ball is formed at the tip of one leg 242A. A projection 247 for coupling and a recess 248 into which the projection 247 is fitted are formed in two bent portions 246a (portions that become shoulder portions 246) of the outer end surface 241c along the line L of the divided bodies 240A and 240A. The circulating parts 240 are assembled by joining the same divided bodies 240A and 240A shown in FIG. 20, and a ball return path 245 by two grooves 245a is formed therein.

  In the ball screw device 201 configured as described above, the ball 230 rolling on the load rolling path formed by the screw grooves 211 and 221 is circulated through the circulation component 240. That is, the ball 230 moves around the screw shaft 210 a plurality of times while moving along the load rolling path, and reaches the end point of the load rolling path (the intersection of the circulating component 240 and the load rolling path). From one end (opening), it is crawled up into the circulation component 240.

  At this time, when the ball 230 collides with the tongue 242a provided at the end of the circulation component 240, the ball 230 is scooped up from the load rolling path and guided into the circulation component 240 along the tongue 242a. The The scooped ball 230 passes through the circulating component 240 to the other end (opening) of the circulating component 240, and is guided by a tongue 242a provided at the end to load from the circulating component 240. Returned to the starting point of the rolling path.

  In this way, the ball 230 that rolls in the load rolling path is circulated indefinitely by the circulating component 240 that communicates the starting point and the end point of the load rolling path, so the screw shaft 210 and the nut When the 220 and the ball 220 are relatively rotated, the screw shaft 210 and the nut 220 continuously move relative to each other in the axial direction through the rolling of the ball 230. In addition, a resin or metal spacer ball or holding piece 270 (see FIG. 21A) smaller than the ball subjected to the load may be interposed between the adjacent balls 230. Further, the cross-sectional shape of the thread grooves 211 and 221 may be an arc shape or a gothic arc shape.

Here, the circulation component 240 of the present embodiment is a circulation component of a tangential scooping method. That is, the ball 230 is scooped up to the circulating component 240 in the tangential direction from the load rolling path, and is circulated so that the ball 230 is returned from the circulating component 240 to the load rolling path along the tangential direction of the load rolling path. The component 240 is connected to the through holes (circulation holes) 223 and 223.
As described above, since the circulation component 240 is formed of a synthetic resin material, it is possible to suppress the generation of noise, vibration, and the like as compared with a ball screw device using a metal component as the circulation component 240. Further, by forming the through holes 223 and 223 in an oval shape along the thread grooves 211 and 221, the possibility that the through holes 223 and 223 interfere with the thread groove 221 even if the diameter of the ball 230 is increased is reduced. Therefore, even when the groove pitch of the thread groove 211 (221) is small or when the thread groove 211 (221) is a multi-thread thread groove, the above-described tangential scooping method can be applied.

[Strain gauge]
In the ball screw device 201 of this embodiment, as shown in FIGS. 21A and 21B, a strain gauge 260 as a sensor is installed in the tongue portion 242a.
The strain gauge 260 is connected to the detection unit 261 that detects vibration and collision force during operation of the ball screw device 201 and is detected, and the detected vibration and collision force during operation of the ball screw device 201 are used as signals. And a lead wire 262 for transmission. The strain gauge 260 is fixed to the tongue portion 242a by joining the detection portion 261 to the tongue portion 242a of the circulating component 240 with an adhesive or the like.

  The reason why the strain gauge 260 is installed in the tongue portion 242a in this way is that it is suitable for monitoring the vibration of the ball screw device 201 because the ball frequently collides with the tongue portion 242a. That is, this installation location is suitable for obtaining information for monitoring the fatigue strength of the tongue portion 242a due to the collision force of the ball 230 applied to the tongue portion 242a and the repeated load.

  Further, by installing the strain gauge 260 on the tongue portion 242a, an excessive load (due to a collision force of the ball 230) or breakage of the tongue portion 242a due to fatigue failure can be detected in advance and used for prevention. Since the tongue portion 242a is an important part for guiding the ball 230 into the circulating component 240, detecting the collision force applied to this part is extremely important for grasping the state of the ball screw device 201. is important. In particular, if the tongue 242a breaks, the ball 230 cannot be circulated, and the ball screw device 201 may be locked (become non-rotatable), so detection of the state of the tongue 242a is extremely important.

  On the other hand, the through hole 223 of the nut 220 may be provided with a groove (not shown) into which the lead wire 262 is inserted in order to guide the lead wire 262 connected to the detection unit 261 of the strain gauge 260 to the outside. . In accordance with the installation in the groove portion, the lead wire 262 is preferably covered with a covering portion at a portion exposed to the outside from the groove portion. On the other hand, the portion where the lead wire 262 is fitted in the groove (the portion from the portion covered by the covering portion (the surface of the nut 220) to the portion connected to the detecting portion 261) is provided with an electrical insulating coating. Preferably it is.

  In this way, by applying an electrical insulating coating to the lead wire 262 in the section from the detection unit 261 to the covering unit, even if the circulating component 240 is made of metal, the electrical circuit of the strain gauge 260 (detection unit 261) is short-circuited. Without this, the lead wire 262 can be joined to the circulation component 240. Further, since the groove portion can be made shallower than when the covering portion having a large cross-sectional area is wired in the section, the processing time of the groove portion in the nut 220 can be shortened.

A part of the covered wire 263 is also preferably joined to the circulation component 240. By doing so, even when the lead wire 262 is pulled, no force is directly applied to the lead wire 262 itself, so that disconnection of the lead wire 262 can be prevented.
The strain gauge 260 can withstand the use environment without interfering with the operation of the ball screw device 201 used in the present embodiment, and detects necessary information such as vibration and collision force during the operation of the ball screw device 201. If possible, there is no particular limitation, and it is appropriately selected according to the purpose. As such a strain gauge 260, a strain gauge for general stress measurement capable of measuring (detecting) up to a maximum elongation of about 5% can be mentioned, and for example, a KFG type strain gauge manufactured by Kyowa Denki Co., Ltd. can be mentioned.

Since the detection unit 261 of the strain gauge 260 is generally thin and small in size, it requires almost no space for installing the sensor, and there are no strict restrictions on the mounting position. Compactness can be achieved.
In addition, by using the strain gauge 260 of the present embodiment, the strain gauge 260 as a sensor can be easily installed at a site that is difficult to install with a vibration sensor, so that vibration and collision force can be detected effectively. It is possible to prevent the tongue portion 242a from being broken.

(Seventh embodiment)
Next, a seventh embodiment of the ball screw device according to the present invention will be described with reference to the drawings. In addition, since this embodiment differs only in the installation position of a strain gauge from the above-mentioned 6th Embodiment, description is abbreviate | omitted about the same structure which attached | subjected the same code | symbol as the above-mentioned embodiment. 22A and 22B are diagrams showing a configuration of a ball screw device according to a seventh embodiment of the present invention. FIG. 22A is a cross-sectional view taken along a plane orthogonal to the axial direction, and FIG. 22B is a strain sensor of a circulating component. It is a perspective view which shows an installation position.
As shown in FIGS. 22A and 22B, in the ball screw device 201 of this embodiment, a strain gauge 260 as a sensor is installed in the scooping portion 243 of the circulating component 240.

Here, the scooping portion 243 is an entrance when the ball 230 is inserted into the circulation component 240. The strain gauge 260 is joined to the scooping portion 243 of the circulating component 240 with an adhesive or the like. The strain gauge is preferably joined to the outside of the scooping portion 243 opposite to the tongue portion 242a.
Therefore, excessive collision force and clogging by the ball 230, lifting of the circulating component 240 due to excessive pushing force against the circulating component 240, and the mounting component 250 (see FIG. 18) for fixing the circulating component 240 and the circulating component 240 to the nut 220. Damage can be detected in advance.
In the present embodiment, a part of the covering portion is also joined to the circulation component 240. Thereby, even when the lead wire 262 is pulled, no force is directly applied to the lead wire 262 itself, so that the disconnection of the lead wire 262 can be prevented.

(Eighth embodiment)
Next, an eighth embodiment of the ball screw device according to the present invention will be described with reference to the drawings. In addition, since this embodiment differs only in the installation position of a strain gauge from the above-mentioned 6th Embodiment, description is abbreviate | omitted about the same structure which attached | subjected the same code | symbol as the above-mentioned embodiment. FIGS. 23A and 23B are views showing the configuration of the ball screw device according to the eighth embodiment of the present invention, in which FIG. 23A is a cross-sectional view taken along a plane orthogonal to the axial direction, and FIG. A top view and (c) are perspective views showing an installation position of a strain sensor in a circulating component.

  As shown in FIGS. 23A to 23C, in the ball screw device 201 of the present embodiment, a strain gauge 260 as a sensor is installed in a bent portion 244 of the circulating component 240. The strain gauge 260 is joined to the bent portion 244 of the circulating component 240 with an adhesive or the like. Here, the bent portion 244 is an outer peripheral surface corresponding to a location where the movement direction of the ball 230 changes in the circulating component 240, that is, an inflection point portion in the trajectory of the ball 230 in the U-shaped circulating component 240 and The outer peripheral surface of the circulating component 240 corresponding to the vicinity thereof is indicated.

Since the bent portion 244 of the circulating component 240 is a portion where the ball collides and the movement direction of the ball changes, the vibration of the ball screw device 201 is preferably monitored by installing a strain gauge 260 on the bent portion 244. can do. In particular, this installation location is suitable for obtaining information for monitoring the collision force of the ball 230 applied to the bent portion 244 and the force by which the circulating component 240 is pushed up by circulation of the ball 230.
Therefore, excessive collision force and clogging by the ball 230, lifting of the circulating component 240 due to excessive pushing force against the circulating component 240, and the mounting component 250 (see FIG. 18) for fixing the circulating component 240 and the circulating component 240 to the nut 220. Damage can be detected in advance.

Further, in this embodiment, unlike the above-described sixth embodiment, it is not necessary to form a groove or the like for wiring a lead wire in the nut 220, and the manufacturing efficiency is high.
Furthermore, in this embodiment, a part of the covering portion of the lead wire is also joined to the circulation component 240. Thereby, even when the lead wire 262 is pulled, no force is directly applied to the lead wire 262 itself, so that the disconnection of the lead wire 262 can be prevented.

(Ninth embodiment)
Next, a ninth embodiment of the ball screw device according to the present invention will be described with reference to the drawings. In addition, since this embodiment employ | adopts the installation position in the above-mentioned 6th-8th embodiment as an installation position of a strain gauge, it demonstrates about the same structure which attached | subjected the same code | symbol as the above-mentioned embodiment. Is omitted. 24A and 24B are diagrams showing the configuration of the ball screw device according to the ninth embodiment of the present invention, in which FIG. 24A is a cross-sectional view taken along a plane orthogonal to the axial direction, and FIG. It is a perspective view which shows an installation position.
As shown in FIGS. 24A and 24B, in the ball screw device 201 of the present embodiment, the strain gauge 260 as a sensor is connected to the tongue portion 242a, the scooping portion 243, and the bent portion 244 of the circulating component 240. is set up. The strain gauge 260 is joined to the tongue part 242a, the scooping part 243, and the bent part 244 of the circulating component 240 with an adhesive or the like.

In this embodiment, since the circulation component 240 is made of resin, the strain gauge 260 is embedded in the circulation component 240.
Thus, by installing the strain gauge 260 on the tongue part 242a, the scooping part 243, and the bent part 244 of the circulating part 240, due to an excessive collision force by the ball 230 and an excessively pushing force to the circulating part 240, It is possible to detect in advance a holding part (not shown) for fixing the circulation part 240 to the nut 220 and the breakage of the circulation part 240.

In addition, by integrally forming the strain gauge 260 and the circulating component 240, the time for joining the strain gauge 260 can be reduced, and the collision force and vibration of the ball 230 can be detected with higher sensitivity. .
The ball screw device according to the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

[Tenth embodiment]
Next, a tenth embodiment of the ball screw device according to the present invention will be described with reference to the drawings.
FIG. 25 is a cross-sectional view (cross-sectional view cut along a plane along the axial direction) illustrating a tenth embodiment of the ball screw device. FIG. 26 is a front view of the ball screw device shown in FIG. 25, and the right half of the seal is not shown. Further, FIG. 27 is a view showing an end deflector and a strain gauge provided in the ball screw device of FIG. 25, and is a view for explaining an attachment state of the end deflector and the strain gauge. FIG. 27A is a side view of the end deflector, FIG. 27B is a plan view, and FIG. 27C is a side view of the side opposite to (a).

  As shown in FIGS. 25 and 26, the ball screw device 301 includes a screw shaft 303 having a helical screw groove 303a on the outer peripheral surface and a helical screw groove 305a facing the screw groove 303a of the screw shaft 303 on the inner periphery. A plurality of balls 309 that are rotatably loaded in a spiral load rolling path 307 formed by both screw grooves 303a and 305a, and a through hole formed in the nut 305. And a ball circulation path 311 for circulating the ball 309 from the end point of the load rolling path 307 back to the start point, and a pair of the ball 309 that scoops up from the end point of the load rolling path 307 and guides it to the end of the ball circulation path 311 The end deflector 312, the strain gauge 320 attached to the end deflector 312, and the screw shaft 3 mounted on the inner peripheral surfaces of both axial ends of the nut 305. A substantially annular seal 313, 313 for sealing the opening of the gap formed between the 3 outer peripheral surface and the inner peripheral surface of the nut 305, and a.

  That is, the ball 309 moves around the screw shaft 303 while moving in the load rolling path 307 to reach the end point of the load rolling path 307, where it is scooped up from the load rolling path 307 by the end deflector 312. It enters one end of the circulation path 311 (the left end in FIG. 25). The ball 309 entering the ball circulation path 311 passes through the ball circulation path 311 and reaches the other end (the right end in FIG. 25) of the ball circulation path 311, and then the load rolling is performed by an end deflector (not shown). The starting point of the path 307 is returned.

  In addition, the raw material of the screw shaft 303, the nut 305, and the ball 309 is not particularly limited, and general materials can be used, and examples thereof include metals such as steel and ceramics. Further, the material of the end deflector 312 is not particularly limited, and resin or metal is used, but resin is more preferable. Furthermore, the cross-sectional shape of the screw grooves 303a and 305a (the cross-sectional shape when cut along a plane orthogonal to the longitudinal direction of the screw grooves 303a and 305a) may be an arc shape (single arc shape) or a gothic arc shape. . Further, the seal 313 may not be provided.

  In such a ball screw device 301, when the nut 305 and the screw shaft 303 that are screwed to the screw shaft 303 through the ball 309 are relatively rotated, the screw shaft 303 and the nut are moved through the rolling of the ball 309. 305 is relatively moved in the axial direction. An endless ball path is formed by the load rolling path 307 and the ball circulation path 311, and the ball 309 circulates infinitely in the ball path. Continuous relative movement is possible.

  Here, the circulation system of the balls 309 in the ball screw device 301 of the present embodiment will be described in more detail with reference to FIGS. In the present embodiment, as a circulation system of the balls 309, a deflector system in which a through hole provided in the nut 305 is a ball circulation path 311 is adopted. That is, the end deflector 312 that lifts the ball 309 from the end point of the load rolling path 307 and guides it to one end (the left end in FIG. 25) of the ball circulation path 311, and the ball 309 other than the ball circulation path 311. End deflectors (not shown in FIG. 25) for guiding from the end (the right end in FIG. 25) to the starting point of the load rolling path 307 are provided at both ends of the nut 305 in the axial direction.

  The nut 305 is formed with a ball circulation path 311 composed of a through hole extending substantially in the axial direction, and both ends of the ball circulation path 311 are arranged in the vicinity of the start point and end point of the load rolling path 307, respectively. . The ball 309 moves from the load rolling path 307 to the ball circulation path 311 at the end point of the load rolling path 307, and the ball 309 from the ball circulation path 311 to the load rolling path 307 at the start point of the load rolling path 307. However, in order to smoothly move the ball 309, end deflectors 312 for guiding the movement of the ball 309 are disposed at the end point and the start point of the load rolling path 307, respectively.

  Of the two end deflectors 312 and 312, the end deflector 312 disposed at the left axial end in FIG. 25 scoops up the ball 309 from the end point of the load rolling path 307 and ends one end of the ball circulation path 311. However, the nut 305 is fitted in a recess 314 provided on the end surface of one end portion in the axial direction (left end portion in FIG. 25) (see FIGS. 25 and 26). On the other hand, the end deflector disposed at the right axial end in FIG. 25 guides the ball 309 from the other end of the ball circulation path 311 to the starting point of the load rolling path 307. It is fitted into a recess provided on the end surface of the end (the right end in FIG. 25).

  Both end deflectors 312 and 312 include a fitting portion 317 that fits into the recess 314 of the nut 305, and a tongue portion 318 that protrudes from the fitting portion 317. When fitted in the recess 314, the tongue 318 is disposed so as to protrude into the load rolling path 307 (see FIG. 26). Therefore, the ball 309 that has rolled to the end point of the load rolling path 307 changes its traveling direction by colliding with the tongue 318 of the left end deflector 312 in FIG. 25, and is scooped up from the load rolling path 307. .

  Then, the ball 309 scooped up by the tongue 318 is guided to the end of the ball circulation path 311 along a curved guide path 319 formed of a groove or a hole formed in the end deflector 312. The ball 309 guided to the end of the ball circulation path 311 passes through the ball circulation path 311 to the other end of the ball circulation path 311, and the guide path and tongue of the right end deflector in FIG. (Not shown) and returned to the starting point of the load rolling path 307.

  When the ball screw device 301 is rotated in the reverse direction, the functions of both end deflectors 312 and 312 are also reversed. That is, in the case of reverse rotation, the left end deflector 312 in FIG. 25 has a function of guiding the ball 309 from the end of the ball circulation path 311 to the starting point of the load rolling path 307, and the right side in FIG. This end deflector has a function of scooping up the ball 309 from the end point of the load rolling path 307 and guiding it to the end of the ball circulation path 311.

  As described above, the ball screw device 301 according to this embodiment includes the strain gauge 320 that detects strain. That is, the strain gauge 320 is joined to the surface of the end deflector 312. When the ball screw device 301 is driven, the ball 309 circulates in the ball passage, and the ball 309 collides with the tongue portion 318 of the end deflector 312, and distortion occurs in the end deflector 312 due to this collision. Therefore, the state of the ball screw device 301 can be monitored by detecting and monitoring the vibration and impact force resulting from the collision by the strain gauge 320.

  The location where the strain gauge 320 is joined is not particularly limited, but it is preferred that the strain gauge 320 be joined to a location where vibration or impact force due to the collision of the ball 309 can be easily detected. In the ball screw device 301 of the present embodiment, a portion located in the vicinity of the curved portion of the guide path 319 among the side surfaces of the end deflector 312 exposed to the end portion in the axial direction when fitted into the recess 314 of the nut 305. A strain gauge 320 is bonded to the substrate (see FIGS. 25 to 27). Since the curved portion of the guide path 319 is a portion where the traveling direction of the ball 309 changes, the ball 309 is clogged in the guide path 319 or the end deflector 312 is detected by detecting vibrations and loads acting on the curved portion. It is possible to detect an abnormality of the ball screw device 301, such as lifting from the concave portion 314.

  Further, since the strain gauge is generally thin and small, unlike a vibration sensor such as an accelerometer, there is almost no space occupied by the joined strain gauge 320. Therefore, the ball screw device 301 is compact even if the strain gauge 320 is provided. In addition, since the strain gauge can be easily installed at a location where installation is difficult in the case of a vibration sensor, it has an advantage that vibration and impact force can be detected effectively.

  The strain gauge 320 includes a main body portion 321 that detects strain and a lead wire 322 that is a lead wire. The structure of the lead wire 322 is not particularly limited. For example, the lead wire 322 having a structure in which the metal wire 322a is covered with a covering material is preferable. The main body portion 321 is joined to the surface of the end deflector 312 and the lead wire 322 is connected to a control unit including a personal computer (not shown). When vibration or load is detected by the main body portion 321, an output is sent from the main body portion 321 to the control unit via the lead wire 322, and the state of the ball screw device 301 is monitored by the control unit.

  When joining the strain gauge 320 to the surface of the end deflector 312, only the main body portion 321 is joined to the surface of the end deflector 312, and the lead wire 322 may not be joined, but the main body portion 321 and the lead wire 322 may be joined. Of these, it is preferable to join both the covering portion 322 b in which the metal wire 322 a is covered with the covering material to the surface of the end deflector 312. Then, even when the lead wire 322 has a small diameter, disconnection can be prevented.

The method for joining the strain gauge 320 to the surface of the end deflector 312 is not particularly limited, but adhesion with an adhesive is preferable. FIG. 27B shows a state in which the main body portion 321 of the strain gauge 320 and a part of the covering portion 322 b are bonded with an adhesive 324. However, only one of the main body portion 321 and the covering portion 322b may be bonded with an adhesive, and the other may be joined by another method.
The application of the ball screw device 301 of this embodiment is not particularly limited, but can be suitably used as a part such as a machine tool, an injection molding machine, a semiconductor manufacturing apparatus, an automobile part, and a positioning apparatus.

[Eleventh embodiment]
Next, an eleventh embodiment of the ball screw device according to the present invention will be described with reference to the drawings.
FIG. 28 is a cross-sectional view (cross-sectional view cut along a plane along the axial direction) for explaining an eleventh embodiment of the ball screw device. FIG. 29 is a front view of the ball screw device of FIG. 28, and illustration of the seal is omitted in the right half. Further, FIG. 30 is a view showing an end deflector and a strain gauge provided in the ball screw device of FIG. 28, and is a view for explaining an attachment state of the end deflector and the strain gauge. 30A is a side view of the end deflector, FIG. 30B is a plan view, and FIG. 30C is a side view of the side opposite to (a).

Since the configuration, operation, effects, and the like of the ball screw device 301 of the eleventh embodiment are substantially the same as those of the tenth embodiment, only the different parts will be described and the description of the same parts will be omitted. In the following description, the same or equivalent parts as those of the ball screw device 301 of the tenth embodiment will be described using the same reference numerals as those of the tenth embodiment.
In the tenth embodiment, a strain gauge is formed on a portion of the side surface of the end deflector 312 that is exposed to the end portion in the axial direction when fitted into the recess 314 of the nut 305, in the vicinity of the curved portion of the guide path 319. 320 is joined, but in the eleventh embodiment, the strain gauge 320 is joined to the surface of the tongue 318 of the end deflector 312 (see FIGS. 29 and 30).

Since the tongue portion 318 is a portion that guides the ball 309 from the load rolling path 307 to the scooping guide path 319, if the tongue portion 318 breaks, the ball screw device 301 does not function. Therefore, it is extremely important to grasp the collision situation of the ball 309 with the tongue 318. If the strain gauge 320 is joined to the surface of the tongue portion 318, the collision state of the ball 309 with the tongue portion 318 can be grasped with high accuracy, so that the tongue portion 318 can be prevented from being broken.
Note that the strain gauge 320 may be joined to a portion of the surface of the end deflector 312 near the tongue portion 318, for example, a portion of the surface of the fitting portion 317 adjacent to the root portion of the tongue portion 318.

[Twelfth embodiment]
Next, a twelfth embodiment of the ball screw device according to the present invention will be described with reference to the drawings.
FIG. 31 is a sectional view for explaining a twelfth embodiment of the ball screw device (a sectional view cut along a plane along the axial direction). FIG. 32 is a front view of the ball screw device of FIG. 31, and the right half is not shown in the seal. Further, FIGS. 33 and 34 are views showing an end deflector and a strain gauge provided in the ball screw device of FIG. 31, and are diagrams for explaining an attachment state of the end deflector and the strain gauge. (A) of FIG.33 and FIG.34 is a side view of an end deflector, (b) is a top view, (c) is a side view on the opposite side to (a).

Since the configuration, operation, effects, and the like of the ball screw device 301 of the twelfth embodiment are substantially the same as those of the tenth embodiment, only different parts will be described and description of the same parts will be omitted. In the following description, the same or equivalent parts as those of the ball screw device 301 of the tenth embodiment will be described using the same reference numerals as those of the tenth embodiment.
In the tenth embodiment, the strain gauge 320 is bonded to the surface of the end deflector 312. However, in the twelfth embodiment, the strain gauge 320 is embedded in the end deflector 312 for bonding. If the strain gauge 320 is embedded in the end deflector 312, vibrations and impact forces resulting from the collision of the ball 309 can be detected with higher sensitivity than when the strain gauge 320 is bonded to the surface.

  The location where the strain gauge 320 is embedded is not particularly limited, but it is preferable that the strain gauge 320 is embedded in a location where vibration or impact force due to the collision of the ball 309 can be easily detected. For example, as shown in FIG. 33, a portion located in the vicinity of the curved portion of the guide path 319, directly below the side surface of the end deflector 312 exposed to the axial end when the nut 305 is fitted into the recess 314. Alternatively, the strain gauge 320 (main body portion 321) may be embedded. Also, as shown in FIG. 34, a strain gauge 320 (main body portion 321) may be embedded immediately below the surface of the tongue 318. Alternatively, although not shown, the strain gauge 320 is provided directly below the vicinity of the tongue portion 318 in the surface of the end deflector 312, for example, directly below the portion adjacent to the root portion of the tongue portion 318 in the surface of the fitting portion 317. It is possible to embed the (main body portion 321).

  When the strain gauge 320 is embedded in the end deflector 312, the main body portion 321 is entirely embedded in the end deflector 312, and most of the lead wire 322 except the portion close to the main body portion 321 is not embedded, but the lead wire 322 is not embedded. Of these, a part of the covering portion 322b in which the metal wire 322a is covered with a covering material is preferably joined to the surface of the end deflector 312 with an adhesive 324 or the like (see FIGS. 33 and 34).

  The method for embedding the strain gauge 320 in the end deflector 312 is not particularly limited, and a concave portion (not shown) is provided on the surface of the end deflector 312 and the main body portion 321 of the strain gauge 320 is fitted into the concave portion. However, when the end deflector 312 is made of resin, the strain gauge 320 is embedded by integrally molding the end deflector 312 and the strain gauge 320 by resin insert molding using the strain gauge 320 as an insert. Further, the end deflector 312 may be manufactured. By manufacturing the end deflector 312 by such integral molding, the labor and time for joining the strain gauge 320 to the end deflector 312 can be reduced.

(13th Embodiment)
Next, a thirteenth embodiment of the ball screw device according to the present invention will be described with reference to the drawings.
FIGS. 35A and 35B are views showing the configuration of the ball screw device according to the thirteenth embodiment, wherein FIG. 35A is a perspective view and FIG. 35B is a partial cross-sectional view along the axial direction of the nut. FIG. 36 is a view showing a configuration of a circulating top in a thirteenth embodiment of the ball screw device, where (a) is a perspective view, (b) is a plan view, (c) is a side view, and (d). FIG. FIG. 37 is a partial cross-sectional view taken along a direction orthogonal to the axial direction in the thirteenth embodiment of the ball screw device. FIGS. 38A and 38B are views showing the configuration of the circulating top in the thirteenth embodiment of the ball screw device, wherein FIG. 38A is a rear view and FIG. 38B is a side view.

<Ball screw device>
As shown in FIGS. 35A and 35B, the ball screw device 401 of this embodiment includes a screw shaft 410, a nut 420, a ball 430, and a circulating top 440 as a circulating component.
The screw shaft 410 has a helical thread groove 411 having a predetermined lead formed on the outer peripheral surface thereof. The nut 420 has a substantially cylindrical shape, and an inner diameter thereof is formed to be larger than an outer diameter of the screw shaft 410. The nut 420 is externally fitted to the screw shaft 410 with a predetermined gap. The nut 420 has a flange 422 for coupling to a guide object at one end thereof. A spiral thread groove 421 having a lead equal to the lead of the screw shaft 410 is formed on the inner peripheral surface of the nut 420. A load rolling path having a substantially circular cross section is formed by the screw groove 411 of the screw shaft 410 and the screw groove 421 of the nut 420 facing the screw groove 411. A plurality of balls 430 are filled in the load rolling path.

  Further, the nut 420 is formed with a circulation top insertion hole 423 for attaching the circulation top 440. The circulation top insertion hole 423 is a long hole penetrating from the outer periphery of the nut 420 toward the inner periphery. The long hole is processed by, for example, an end mill, and is formed by inclining the end mill by a predetermined angle with respect to a line orthogonal to the center line of the nut 420. This predetermined angle is set to an angle at which the ball 430 rolling on the screw groove 421 does not change direction abruptly by the ball return groove 441 formed in the circulation top 440. A plurality (for example, three) of the circulating top insertion holes 423 are machined in accordance with the number of the circulating tops 440 at equal intervals in the circumferential direction of the nut 420.

  A ball return groove 441 that connects one end of the load rolling path to the other end of the load rolling path immediately before the winding is formed in the circulating top 440 mounted in each circulation top insertion hole 423 of the nut 420. Yes. Then, by this ball return groove 441, the ball 430 rolling on the load rolling path toward the circulating top 440 is scooped up in the radial direction of the screw shaft 410, and further over the thread, The ball 430 can be circulated by returning to the load rolling path (before the lead). A substantially annular endless circulation path is formed outside the screw shaft 410 by a path formed by the ball return groove 441 and the load rolling path. Accordingly, the ball 430 rolls between the screw groove 411 and the screw groove 421 in accordance with the relative rotation of the screw shaft 410 with respect to the nut 420, so that the nut 420 moves relative to the screw shaft 410. It is possible to move linearly in the axial direction.

[Circulation top]
Here, the above-mentioned circulating top 440 will be described in more detail with reference to FIGS. 36 (a) to (d).
The circulation top 440 is formed from, for example, a sintered alloy, and the outer shape thereof is formed in alignment with the circulation top insertion hole 423 provided in the nut 420. The outer shape of the circulation top 440 is formed to be slightly smaller than the inner shape of the circulation top insertion hole 423 to such an extent that a slight gap is generated between the opening of the circulation top insertion hole 423. Here, in this circulation top 440, when the circulation top 440 is attached to the nut 420, it engages with the circulation top insertion hole 423, and a step portion 442 is formed at the peripheral portion of the surface on the outer peripheral side of the nut 420. Has been. A gap between the step 442 and the circulation top insertion hole 423 is filled with a sealing agent along the entire periphery including the step 441 of the circulation top 440. With this sealing agent, the circulating top 440 is fixed to the nut 420, and leakage of oil (grease, lubricating oil, etc.) from the clearance between the circulating top insertion hole 423 and the circulating top 440 is prevented.

  Furthermore, a ball return groove 441 extending in a substantially S shape in the longitudinal direction is formed on the back surface 440 c side of the circulating top 440 so as to open toward the inner peripheral side of the nut 420. This substantially S-shape is a shape determined from the function for returning the ball 430. That is, the ball return groove 441 changes the course of the ball 430 so as to return the ball 430 rolling on the load rolling path to the load rolling path one turn before and aligns with the load rolling path. is necessary. Therefore, when the planar shape is a cam curve, for example, a cam curve corresponding to a modified sine curve is combined to form a substantially S-shape so as to suppress rapid fluctuations in acceleration relative to the lift. Has been. Further, the ball return groove 441 has a short cross section of the circulation top 440 from the ball scooping portion 443 at both longitudinal ends of the circulation top 440 toward the center in the longitudinal direction of the circulation top 440. A continuous U-shape having an inner diameter aligned with the outer diameter is formed, and this forms a groove shape integrally with the aforementioned substantially S-shape.

  One circulating top 440 is provided for one turn of the ball row filled in the ball screw device 410. That is, since the number of turns of the ball 430 is determined from the load applied to the ball screw device 410, the number of the circulating tops 440 is appropriately determined (for example, three) according to the load applied to the ball screw device 410.

[Strain gauge]
In the ball screw device 401 of this embodiment, a strain gauge 450 as a sensor is installed on the upper surface 440a of the circulating top 440, as shown in FIGS. 37, 38 (a) and 38 (b). This installation location is preferably the surface (upper surface 440a) of the circulating top 440 corresponding to the back side of the ball return groove 441.
The strain gauge 450 is connected to the detection unit 451 for detecting vibration and collision force during operation of the ball screw device 401, and is detected, and the detected vibration and collision force during operation of the ball screw device 401 are used as signals. And a lead wire 452 for transmission. The strain gauge 450 is fixed by bonding the detection unit 451 with an adhesive or the like to the upper surface 440a of the circulating top 440, in particular, the portion corresponding to the back side of the bottom of the ball return groove 441.

  The reason why the strain gauge 450 is installed behind the bottom of the ball return groove 441 on the upper surface 440a of the circulating top 440 is because it is suitable for simply monitoring the vibration of the ball screw device 401. That is, this installation location is suitable for obtaining information for monitoring the collision force of the ball 430 applied to the ball return groove 441 formed in an S shape and the fatigue condition of the ball return groove 441 due to repeated load.

Moreover, it is preferable that at least a part of the lead wire 452 is covered with a covering portion (electrical insulating film).
In this way, by applying an electrical insulating film to the lead wire 452 in the section from the detection unit 451 to the covering unit, even if the circulating top 440 is made of metal, the electrical circuit of the strain gauge 450 (detection unit 451) is short-circuited. Without this, the lead wire 452 can be joined to the circulation top 440.

In addition, it is preferable that a part of the covering portion is also joined to the circulation top 440. By doing so, even when the lead wire 452 is pulled, no force is directly applied to the lead wire 452 itself, so that the disconnection of the lead wire 452 can be prevented.
The strain gauge 450 withstands the use environment without interfering with the operation of the ball screw device 401 used in the present embodiment, and detects necessary information such as vibration and collision force during the operation of the ball screw device 401. If possible, there is no particular limitation, and it is appropriately selected according to the purpose. Examples of such a strain gauge 460 include a strain gauge for general stress measurement that can measure (detect) up to a maximum elongation of about 5%. For example, a KFG type strain gauge manufactured by Kyowa Denki Co., Ltd. may be used.

According to the present embodiment, the detector 451 of the strain gauge 450 is generally thin and small in size, and therefore requires little space for providing a sensor, and there are no strict restrictions on the mounting position. As a result, the ball screw device 401 can be made compact.
In addition, by using the strain gauge 450 of the present embodiment, the strain gauge 450 as a sensor can be easily installed in a site that is difficult to install with a vibration sensor, so that vibration and collision force can be detected effectively. .

(Fourteenth embodiment)
Next, a fourteenth embodiment of the ball screw device will be described with reference to the drawings. In addition, since this embodiment differs only in the installation position of a strain gauge from the above-mentioned 13th Embodiment, description is abbreviate | omitted about the same structure which attached | subjected the same code | symbol as the above-mentioned embodiment. FIG. 39 is a partial cross-sectional view taken along a direction orthogonal to the axial direction in the fourteenth embodiment of the ball screw device. FIGS. 40A and 40B are views showing a configuration of a circulating top in the fourteenth embodiment of the ball screw device, wherein FIG. 40A is a rear view and FIG. 40B is a side view.

As shown in FIGS. 39, 40 (a), and 40 (b), in the ball screw device 401 of this embodiment, a strain gauge 460 as a sensor is installed in the vicinity of the ball scooping portion 443 on the side surface 440 b of the circulating top 440. ing.
Here, the ball scooping portion 443 is a portion at both ends in the longitudinal direction of the ball return groove 441. The strain gauge 460 is joined with an adhesive or the like in the vicinity of the ball scooping portion 443 on the side surface 440b of the circulating top 440.
Accordingly, it is possible to detect in advance an excessive collision force or clogging by the ball 430, a floating top 440 floating due to an excessive pushing force against the circulating top 440, or a damage to the circulating top 440.

  As described above, the strain gauge 450 is installed in the vicinity of the ball scooping portion 443 on the side surface 440b of the circulating top 440 because the ball frequently collides with the ball scooping portion 443, so that the vibration of the ball screw device is monitored. It is because it is suitable for. That is, this installation location is suitable for obtaining information for monitoring the fatigue strength of the ball scooping portion 443 due to the collision force of the ball 430 applied to the ball scooping portion 443 and the repeated load.

  Further, by installing the strain gauge 450 near the ball scooping portion 443 on the side surface 440b of the circulating top 440, the ball scooping portion 443 can be prevented from being broken due to excessive load (due to the impact force of the ball 430) or fatigue failure. It can be detected in advance and used for prevention. Since the ball scooping portion 443 is an important part for guiding the ball 430 into the circulation top 440, detecting the collision force applied to this part is for grasping the state of the ball screw device 401. Is extremely important. In particular, if the vicinity of the ball scooping portion 443 is damaged, the circulation of the ball 430 may be hindered, and the ball screw device 401 may be locked (become non-rotatable). Detection is extremely important.

  On the other hand, the circulating top insertion hole 423 of the nut 420 is provided with a groove portion (not shown) for inserting the lead wire 452 in order to guide the lead wire 452 connected to the detection portion 451 of the strain gauge 450 to the outside. Also good. In accordance with the installation in the groove portion, the lead wire 452 is preferably covered with a covering portion at a portion exposed to the outside from the groove portion. On the other hand, the portion where the lead wire 452 is fitted in the groove (the portion from the portion covered by the covering portion (the surface of the nut 420) to the portion connected to the detecting portion 451) is provided with an electrical insulating coating. Preferably it is.

In this way, by applying an electrical insulating film to the lead wire 452 in the section from the detection unit 451 to the covering unit, even if the circulating top 440 is made of metal, the electrical circuit of the strain gauge 450 (detection unit 451) is short-circuited. Without this, the lead wire 452 can be joined to the circulation top 440. Further, since the groove portion can be made shallower than when the covering portion having a large cross-sectional area is wired in the section, the processing time of the groove portion in the nut 420 can be shortened.
Note that a part of the covering portion is also preferably joined to the circulation top 440. By doing so, even when the lead wire 452 is pulled, no force is directly applied to the lead wire 452 itself, so that the disconnection of the lead wire 452 can be prevented.

According to the present embodiment, the detector 451 of the strain gauge 450 is generally thin and small in size, and therefore requires little space for providing a sensor, and there are no strict restrictions on the mounting position. As a result, the ball screw device can be made compact.
In addition, by using the strain gauge 450 of the present embodiment, the strain gauge 450 as a sensor can be easily installed at a site that is difficult to install with a vibration sensor, so that vibration and collision force can be detected effectively. In addition, damage in the vicinity of the ball scooping portion 443 can be prevented in advance.
The ball screw device according to the present invention has been described above. However, the ball screw device according to the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. .

The direction in which the strain gauge is attached is not limited to the direction shown in each embodiment, and may be any direction. For example, you may attach in the orthogonal | vertical direction with respect to the direction shown to each above-mentioned embodiment. A rosette gauge may also be used. A guide plate may be used as the ball circulation path. By using the guide plate as the ball circulation path, the vibration of the ball screw device can be easily monitored, and the strain gauge as a sensor can be easily installed with the vibration sensor, similarly to the circulation top 440 described above. Can be easily installed, so that vibration and collision force can be detected effectively.
Although not shown, when the circulation top 440 is made of resin, a method of embedding a strain gauge by insert molding or the like as in the above-described end cap circulation method or end deflector circulation method is also possible.

DESCRIPTION OF SYMBOLS 1 Ball screw apparatus 10 Screw shaft 10a Thread groove 20 Nut 20a Thread groove 22 Groove part 30 Ball (rolling element)
40 Load rolling path 50 Return tube 50a Bent part (curved part)
51 Tang part 60 Strain gauge 61 Detection part 62 Lead wire 63 Covering part 101 Ball screw device 110 Screw shaft 111 Ball screw device groove 120 Nut 121 Through hole 131, 132 End cap 131a, 132a Rolling element circulation groove 131a1, 132a1 Bending part (Curved part)
131b, 132b tongue part 140 ball 151, 152, 153, 154 vibration sensor 161 body part (strain gauge part)
162 Lead wire 201 Ball screw device 210 Screw shaft 211 Screw groove 220 Nut 221 Screw groove 230 Ball (rolling element)
240 Circulating parts 242a Tongue part 243 Scooping part 244 Bending part (curved part)
260 Strain Gauge 261 Detecting Unit 262 Lead Wire 301 Ball Screw Device 303 Screw Shaft 303a Screw Groove 305 Nut 305a Screw Groove 307 Load Rolling Path 309 Ball 311 Ball Circulation Path 312 End Deflector 318 Tongue 319 Guide Path 320 Strain Gauge 321 Main Body 322 Lead wire 322a Metal wire 322b Covering portion 324 Adhesive 401 Ball screw device 410 Screw shaft 411 Screw groove 420 Nut 421 Screw groove 430 Ball (rolling element)
440 Circulating top 440a Upper surface 440b Side surface 440c Rear surface 441 Ball return groove (S-shaped groove)
443 Ball scooping section 450 Strain gauge 451 Detection section 452 Lead wire

Claims (7)

A screw shaft having a helical thread groove on the outer peripheral surface, and a thread groove facing the screw groove of the screw shaft on the inner peripheral surface, is transferred to a spiral load rolling path formed by the both screw grooves. A nut screwed to the screw shaft through a plurality of balls loaded freely, and a ball circulation path for circulating the balls by sending the balls from an end point of the load rolling path to a starting point. In the ball screw device,
A ball screw device comprising a strain gauge in the ball circulation path. The ball circulation path changes a traveling direction of the ball and scoops up the ball from an end point of the ball circulation path, and scoops the ball scooped up by the ball scooping section into the ball circulation path. A curved portion guided to the end of the
The ball screw device according to claim 1, wherein the strain gauge is provided in the ball scooping portion or the curved portion, or in the vicinity thereof.   The ball circulation path is an end cap that is attached to an end portion of the nut and a through hole that penetrates the inside of the nut in the axial direction, and a communication path that communicates between the load rolling path and the through hole; 2. A tangential scooping-up type circulation part, an end deflector, and a circulation top made of two synthetic resin divided bodies divided along the rolling direction of the ball. Or the ball screw apparatus of 2.   The ball screw device according to claim 1, wherein the strain gauge is provided in the ball circulation path.   The ball screw device according to any one of claims 1 to 4, wherein a groove for inserting the lead wire of the strain gauge is provided in the nut.   The ball screw device according to any one of claims 1 to 5, wherein at least a part of the lead wire of the strain gauge is fixed or joined to the ball circulation path.   The ball screw device according to claim 1, wherein the strain gauge is fixed to the ball circulation path with an adhesive.

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