JP2017198337A - Nut attachment, nut assembly, and feed screw device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably reduce backlash occurring in a feed screw mechanism.SOLUTION: A nut attachment 100 is attached to a transmission nut 200 which meshes with a thread groove 309 formed in a screw shaft 300 forming a feed screw mechanism. The nut attachment 100 has: a nut fixing part for fixing the nut attachment 100 to the transmission nut 200; a meshing part which meshes with the thread groove 309; and a biasing part which biases the meshing part so that the meshing part rotates relative to the nut fixing part.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a technique for reducing backlash generated in a feed screw mechanism.

  As a transmission device that converts rotational motion into linear motion, a feed screw mechanism that has a screw shaft and a nut meshed with the screw shaft and moves the nut linearly by rotating the screw shaft is known. . In such a feed screw mechanism, in order to make the nut rotatable with respect to the screw shaft, a gap is provided between the screw groove formed on the screw shaft and the protrusion formed on the nut and meshing with the screw groove. . As described above, when a gap is provided between the thread groove and the projecting portion, when the screw shaft is rotated in one direction and then the rotation direction is reversed, a backlash is generated in which the nut does not move immediately after the rotation direction is reversed. . When backlash occurs, the correspondence between the rotation angle of the screw shaft and the position of the nut is not uniquely determined, so that it is difficult to position the nut with high accuracy.

  Therefore, various techniques for eliminating backlash and increasing the positioning accuracy of the nut have been proposed. For example, in Patent Document 1, in a rolling element type screw drive device that converts a rotary motion of a screw spindle (screw shaft) into a linear motion of a double nut, two individual nuts constituting a double nut that runs on the screw spindle are disclosed. It has been proposed to be able to rotate relative to each other and continuously about the spindle axis and to be fixed in a relative rotational position corresponding to the desired play (backlash) or the desired prestress. Further, Patent Document 2 describes that backlash is removed by urging a first nut and a second nut that can be screwed into a common male screw (screw shaft) in a separating direction.

JP 2000-193064 A JP 2004-347099 A

  However, in the technique proposed in Patent Document 1, since two individual nuts are fixed at a relative rotational position corresponding to a desired play or a desired pre-stress, when the individual nut or the screw spindle is worn, the play is prevented. There is a possibility that the play may not be maintained in a desired state. Moreover, in the technique described in Patent Document 2, since the backlash is removed by urging the first nut and the second nut in the separating direction, the first nut, the second nut, or the common Although the backlash removal function is less likely to be impaired even if the male screw is worn, the backlash may not be properly removed when an external force is applied to bring the first nut and the second nut closer.

  The present invention has been made to solve the above-described conventional problems, and an object thereof is to provide a technique for more stably reducing backlash that occurs in a feed screw mechanism.

  In order to achieve at least a part of the above object, the present invention can be realized as the following forms or application examples.

[Application Example 1]
A feed screw mechanism having a screw shaft in which a thread groove is formed and a transmission nut meshing with the thread groove, and a nut attachment attached to the transmission nut, the nut attaching the nut attachment to the transmission nut A nut attachment comprising: a fixing portion; a meshing portion that meshes with the screw groove; and a biasing portion that biases the meshing portion so as to rotate the meshing portion with respect to the nut fixing portion.

  When the meshing portion is biased so as to rotate with respect to the nut fixing portion that is fixed to the transmission nut, the meshing portion of the nut attachment and the projecting portion that meshes with the thread groove in the transmission nut are separated from the meshing portion. A load is applied so that the parts approach or separate from each other. Therefore, the gap between the meshing portion and the protruding portion and the thread groove can be eliminated, and the backlash can be reduced. In addition, since a load is applied to the meshing portion and the projecting portion when the meshing portion is urged, even if the screw shaft (screw groove), the meshing portion or the projecting portion is worn, the meshing portion and the projecting portion are separated. Since the applied load can be maintained, it is suppressed that the backlash reduction function is impaired due to wear. Furthermore, since the nut attachment and the transmission nut are fixed by the nut fixing portion, and the meshing portion is biased so as to rotate with respect to the nut fixing portion, an external force is applied to the nut attachment and the transmission nut. The variation of the load applied to the meshing portion and the protruding portion by the external force is suppressed, and the state in which the backlash is reduced can be maintained. Therefore, according to the configuration of Application Example 1, it is possible to more stably reduce backlash generated in the feed screw mechanism.

[Application Example 2]
The nut attachment according to Application Example 1, wherein the meshing portion includes a ball and a ball holding ring formed in an annular shape that rotatably holds the ball, and the ball includes the screw. A nut attachment configured such that a part of the ball protrudes inward from the ball holding ring so as to mesh with a groove.

  By holding the ball meshing with the thread groove rotatably with the ball retaining ring, the friction between the nut attachment and the threaded shaft when the threaded shaft is rotated can be further reduced. Therefore, wear of the screw shaft and the ball can be suppressed, and the power transmission efficiency can be further increased.

[Application Example 3]
The nut attachment according to Application Example 1 or 2, wherein the biasing portion is rotatable with respect to the nut fixing portion and is configured to be fixed with respect to the nut fixing portion, and a biasing force. And the engagement portion is configured to be rotatable with respect to the nut fixing portion, and the adjustment member and the engagement portion are rotated with each other in a state where the biasing member is removed. A nut attachment, wherein the biasing member is disposed between the contact portion of the adjustment member and the contact portion of the meshing portion.

  When the nut attachment is attached to the transmission nut and the feed screw mechanism is assembled through the screw shaft through the nut attachment and the transmission nut, the rotation of the meshing portion is restricted with respect to the nut fixing portion. In this state, by rotating the adjustment member relative to the nut fixing portion, the biasing member disposed between the contact portion of the adjustment member and the contact portion of the meshing portion is deformed, and the biasing force is applied to the meshing portion. Will be added. Therefore, according to this application example, when the feed screw mechanism is assembled, the meshing portion can be prevented from being biased, and therefore, the assembly of the feed screw mechanism becomes easier. Further, when the meshing portion is urged after the feed screw mechanism is assembled, it is easy to adjust the urging force. Therefore, it is easy to adjust the operation of the transmission mechanism more appropriately by appropriately adjusting the strength of the force for urging the meshing portion according to the purpose of use of the transmission mechanism.

[Application Example 4]
It is a nut attachment of the application example 3, Comprising: The said adjustment member protrudes from the side opposite to the side attached to the said transmission nut of the said nut fixing | fixed part.

  Since the adjustment member can be rotated more easily with respect to the nut fixing portion by projecting the adjustment member from the side opposite to the side where the transmission nut of the nut fixing portion is attached, And it becomes easier to adjust the urging force.

[Application Example 5]
The nut attachment according to Application Example 1 or 2, wherein the urging portion can be changed in shape in a state where the nut attachment is not attached to the transmission nut, and the nut attachment is attached to the attachment A nut attachment configured to be able to adjust the strength of the force that biases the meshing portion by changing the shape of the biasing portion.

  Generally, when the force for urging the meshing portion is increased, the force required to rotate the nut attachment and the transmission nut with respect to the screw shaft is increased. On the other hand, when the force for urging the meshing portion is weakened, the backlash reduction effect is diminished. Therefore, by making it possible to adjust the strength of the force that biases the meshing portion, the strength of the force that biases the meshing portion is appropriately adjusted according to the purpose of use of the transmission mechanism, and the operation of the transmission mechanism is more appropriate. It becomes possible to adjust to.

[Application Example 6]
The nut attachment according to any one of Application Examples 1 to 5, wherein the transmission nut includes an object fixing part for fixing an object to be driven, and the nut fixing part is the object fixing part. Nut attachment with the same outer shape.

  By making the outer edges of the nut fixing portion and the object fixing portion have the same shape, changes in the shape of the feed screw mechanism caused by attaching the nut attachment can be suppressed. Therefore, it becomes easier to reduce the backlash of the existing feed screw mechanism using a transmission nut.

[Application Example 7]
A nut assembly that meshes with a thread groove provided on a screw shaft and constitutes a feed screw mechanism, and is a first nut that meshes with the thread groove, and a first nut that meshes with the thread groove and is attached to the first nut. And a biasing portion that biases the second nut so as to rotate the second nut relative to the first nut.

  By urging the first and second nuts to rotate relative to each other, the meshing portions provided in each of the first and second nuts and meshing with the thread grooves approach each other. Or the load which leaves | separates can be applied. Therefore, the gap between the meshing portion and the thread groove can be eliminated, and backlash can be reduced. In addition, since the load is applied to the meshing portion by urging the first and second nuts to rotate relatively, the meshing portion is not affected even if the screw shaft (screw groove) or the meshing portion is worn. As a result, the backlash reduction function is prevented from being impaired by wear. Further, since the first and second nuts are biased to rotate relatively, even if an external force is applied to the first and second nuts, fluctuations in the load applied to the meshing portion due to the external force are suppressed. Thus, the state in which the backlash is reduced can be maintained. Therefore, the configuration of Application Example 5 can also more stably reduce backlash that occurs in the feed screw mechanism.

  Note that the present invention can be realized in various modes. For example, in a feed screw mechanism having a screw shaft in which a thread groove is formed and a transmission nut meshing with the screw groove, a nut attachment attached to the transmission nut, a feed screw mechanism or a feed screw device using the nut attachment, a screw shaft It can be realized in a manner such as a nut assembly that meshes with a thread groove provided in the nut, and that constitutes a feed screw mechanism, a feed screw mechanism or a feed screw device using the nut assembly, and the like.

Explanatory drawing which shows the structure of the transmission mechanism to which this invention was applied. Explanatory drawing which shows the specific structure of a nut attachment and a sliding nut. Explanatory drawing which shows the shape of each part of a nut attachment. Explanatory drawing which shows the assembly aspect of a nut attachment. Explanatory drawing explaining the effect | action of the urging | biasing to a ball holding ring and a ball | bowl. Explanatory drawing which shows a mode that a backlash is reduced by applying a load to a ball | bowl and a protrusion part. Explanatory drawing which shows the modification of a structure of a nut attachment. Explanatory drawing which shows the structure of the nut attachment of 2nd Embodiment. The disassembled perspective view which shows the structure of the nut attachment of 3rd Embodiment. Explanatory drawing which shows a mode that a ball | bowl holding ring is urged | biased in 3rd Embodiment. The disassembled perspective view which shows the structure of the nut attachment in 4th Embodiment. Explanatory drawing which shows the structure of the transmission mechanism using a nut assembly.

The form for implementing this invention is demonstrated in the following order.
A. First embodiment:
A1. Transmission mechanism configuration:
A2. Nut attachment and sliding nut configuration:
A3. Nut attachment shape:
A4. Nut attachment assembly:
A5. The action of biasing the ball retaining ring and ball:
A6. Backlash reduction:
A7. Variations of the nut attachment configuration:
B. Second embodiment:
C. Third embodiment:
D. Fourth embodiment:
E. Variations:

A. First embodiment:
A1. Transmission mechanism configuration:
FIG. 1 is an explanatory diagram showing a configuration of a transmission mechanism 10 to which the present invention is applied. The transmission mechanism 10 is a feed screw mechanism (feed screw device) having a nut attachment 100, a sliding nut 200, and a screw shaft 300 in which a screw groove 309 constituting a four-threaded right screw is formed. Although not shown in FIG. 1, the nut attachment 100 and the sliding nut 200 are each configured to mesh with a screw groove 309 formed in the screw shaft 300.

  In the first embodiment, the nut attachment 100 is fixed to the sliding nut 200. For example, as shown in FIG. 1, the nut attachment 100 is fixed to the sliding nut 200 in a state where the nut attachment 100 and the sliding nut 200 are overlapped with each other, and through holes 119 provided in the nut attachment 100 and the sliding nut. This is performed by fixing the nut attachment 100 and the sliding nut 200 to the driven object using a bolt (not shown) passed through a through-hole (not shown) provided in 200. The method for fixing the nut attachment 100 to the sliding nut 200 is not necessarily limited to this. For example, in addition to a through hole that fixes a nut attachment or a sliding nut to an object to be driven, a screw hole is provided in one of the nut attachment and the sliding nut, a through hole is provided in the other, and the bolt is turned into a screw hole through the through hole. The nut attachment and the sliding nut can be fixed by screwing. In addition, a screw is formed on one of the nut attachment and the sliding nut, a female screw that meshes with the male screw is formed on the other, and the nut attachment and the sliding nut are fixed by screwing the male screw into the female screw. You can also.

  As described above, the sliding nut 200 is configured to mesh with the screw groove 309 of the screw shaft 300. Therefore, when the screw shaft 300 is rotated about the central axis C, the sliding nut 200 is moved along the central axis C. Move in the direction Normally, the sliding nut 200 and the screw shaft 300 are relatively positioned between a meshing portion (not shown) that meshes with the screw groove 309 of the screw shaft 300 in the slide nut 200 and the screw groove 309 formed in the screw shaft 300. A gap is provided to enable smooth rotation. Therefore, when the screw shaft 300 is rotated in one direction and then the rotation direction is reversed, the sliding nut 200 does not move immediately after the rotation direction is reversed. As described above, a backlash (also referred to as “lost motion”) in which the sliding nut 200 does not move immediately after the reversal of the rotation direction of the screw shaft 300 is generated, whereby the rotation angle of the screw shaft 300 and the position of the sliding nut 200 are reduced. The correspondence is not uniquely determined. Therefore, it becomes difficult to position the drive target fixed to the sliding nut 200 with high accuracy.

  Although details will be described later, in the first embodiment, by fixing the nut attachment 100 to the sliding nut 200, the screw shaft 300 is rotated about the central axis C, and the nut attachment 100 and the sliding nut 200 are moved to the central axis C. The backlash when moving in the direction of is reduced. Thereby, positioning of the drive target fixed to the nut attachment 100 and the sliding nut 200 can be performed with higher accuracy. As the screw shaft 300 and the sliding nut 200, a commercially available screw shaft and sliding nut can be used, and the detailed configuration thereof is not directly related to the present invention. Therefore, the detailed description about the screw shaft 300 and the sliding nut 200 is omitted.

A2. Nut attachment and sliding nut configuration:
FIG. 2 is an explanatory diagram showing a specific configuration of the nut attachment 100 and the sliding nut 200. FIG. 2A and FIG. 2B show a state in which the nut attachment 100 and the sliding nut 200 are viewed from the same direction as FIG.

  As shown in FIG. 2A, the nut attachment 100 has a large-diameter flange portion 110, a ball holding ring 120, a stopper ring 130, and four balls 140. The flange portion 110 includes two flat portions 111 parallel to the central axis C, a concave portion 112 that accommodates the ball holding ring 120 and the stopper ring 130, a central hole 118 that penetrates in the direction of the central axis C, and four through holes 119. And are provided. The inner diameter of the center hole 118 is set slightly larger than the outer diameter of the screw shaft 300 (FIG. 1). The ball holding ring 120 is configured to hold the ball 140 with a part of the ball 140 protruding inward. Thus, a part (protrusion part) of the ball 140 protruding inward meshes with the screw groove 309 of the screw shaft 300 (FIG. 1). Therefore, the entire ball 140 including the protruding portion of the ball 140 and the ball holding ring 120 can be referred to as a “meshing portion” that meshes with the screw groove 309 as a whole. Specific shapes of the flange portion 110, the ball holding ring 120, the stopper ring 130, and the ball 140 will be described later.

  As shown in FIG. 2B, the sliding nut 200 has a large-diameter flange portion 210 and a threaded portion 220 formed as a female screw that meshes with the thread groove 309 of the screw shaft 300 (FIG. 1). Yes. The flange portion 210 is provided with two flat portions 211 parallel to the central axis C and a central hole 218 penetrating in the direction of the central axis C. The female thread portion 220 is a cylindrical member having an outer diameter that is substantially the same as the inner diameter of the center hole 218 of the flange portion 210, and is fitted into the center hole 218 of the flange portion 210 as shown in FIG. Thus, the flange portion 210 is fixed. The female screw portion 220 is provided with a central hole 228 that penetrates in the direction of the central axis C and a protruding portion 221 that protrudes inward from the central hole 228. The protruding portion 221 is formed so that a cross-sectional shape cut along a plane including the central axis C becomes a semicircular shape. Also in the sliding nut 200, since the protrusion 221 is configured to mesh with the screw groove 309 of the screw shaft 300 (FIG. 1), the protrusion 221 can also be referred to as a “meshing portion” that meshes with the screw groove 309. . In the example of FIG. 2B, the flange portion 210 and the female screw portion 220 are configured as separate members. However, the flange portion 210 and the female screw portion 220 may be formed as an integral member. .

  As apparent from FIGS. 1 and 2, the outer edge of the flange portion 110 of the nut attachment 100 and the flange portion 210 of the sliding nut 200 have the same shape. Further, since the flange portion 110 of the nut attachment 100 is used to fix the nut attachment 100 to the sliding nut 200, it can also be referred to as a “nut fixing portion”. On the other hand, since the flange portion 210 of the sliding nut 200 is used to fix the driving object, it can also be referred to as an “object fixing portion”.

A3. Nut attachment shape:
FIG. 3 is an explanatory view showing the shape of each part of the nut attachment 100. FIGS. 3A to 3C show the flange 110, the ball holding ring 120 and the ball 140, and the stopper ring 130 as viewed from the sliding nut 200 (FIG. 1) side. Yes. Since the surface of the nut attachment 100 on the sliding nut 200 side is a surface on which the nut attachment 100 is attached to the sliding nut 200, it will be hereinafter referred to as “attachment surface” and the sliding nut 200 side is also referred to as “attachment surface side”. Call.

  As shown in FIG. 3A, the recess 112 provided in the flange portion 110 opens to the mounting surface side, and the inner surface is formed in a substantially circular shape. Here, “the inner surface is substantially circular” means that the cross section of the inner surface on the surface orthogonal to the central axis C (FIG. 2) is substantially circular. Further, unless otherwise specified, other surface shapes are also expressed as cross-sectional shapes on a plane orthogonal to the central axis C below. Two fan-shaped elongated portions 113 extending from the bottom of the concave portion 112 to the mounting surface side are provided on the inner surface of the concave portion 112. The extending portions 113 are disposed at both ends of the flange portion 110 in the direction where the flat portion 111 is not provided (the left-right direction in FIG. 3).

  As shown in FIG. 3B, the ball holding ring 120 includes an annular annular portion 121 provided with a central hole 128 penetrating in the direction of the central axis C (FIG. 2), and projects outward from the annular portion 121. And two projecting portions 123. The outer diameter of the annular portion 121 is set slightly smaller than the inner diameter of the elongated portion 113 included in the flange portion 110. Further, the maximum diameter of the protrusion 123 is set to be slightly smaller than the inner diameter of the recess 112 provided in the flange part 110. The thickness of the ball holding ring 120 is set to be slightly shorter than the length from the bottom of the recessed portion 112 of the elongated portion 113 provided on the flange portion 110 to the mounting surface side. Thereby, the ball holding ring 120 can rotate around the central axis C in a state where the ball holding ring 120 and the stopper ring 130 are fitted in the flange portion 110. Further, the inner diameter of the center hole 128 provided in the annular portion 121 is set to be substantially the same as the inner diameter of the center hole 118 provided in the flange portion 110. The annular portion 121 of the ball holding ring 120 is provided with a ball accommodation hole 122 that opens on the opposite side of the mounting surface for accommodating the ball 140. The ball housing hole 122 is a hole having an inner surface that is slightly larger than the outer diameter of the ball 140 and has a depth that is slightly longer than that of the ball 140 and has a substantially circular inner surface. By doing so, the ball 140 is held by the ball holding ring 120 in a rotatable state. By fitting the ball 140 into the ball receiving hole 122, a part of the ball 140 protrudes inward as described above. As shown in FIG. 3B, since the center of the ball receiving hole 122 is located outward from the inner surface of the annular portion 121 of the ball holding ring 120, the opening inside the ball receiving hole 122 is provided. The width can be narrower than the diameter of the ball 140. In this way, it is possible to prevent the ball 140 from dropping out toward the central axis C (FIG. 2). As is clear from FIG. 3B, the ball holding ring 120 is formed in an annular shape as a whole.

  As shown in FIG. 3C, the stopper ring 130 is an annular member provided with a central hole 138 penetrating in the direction of the central axis C (FIG. 2). The inner diameter of the center hole 138 is set to be approximately the same as the inner diameter of the center hole 118 provided in the flange portion 110 and the center hole 128 provided in the annular portion 121 of the ball holding ring 120. The outer diameter of the stopper ring 130 is set to be slightly smaller than the inner diameter of the recess 112 provided in the flange portion 110. Further, the thickness of the stopper ring 130 is set to be substantially the same as the length from the end surface on the attachment surface side of the extending portion 113 provided on the flange portion 110 to the end surface on the attachment surface side of the flange portion 110. Thereby, the ball holding ring 120 and the stopper ring 130 are accommodated in the flange portion 110 so that the stopper ring 130 does not protrude from the mounting surface side of the flange portion 110. Thus, the state in which the ball holding ring 120 in which the ball 140 is fitted into the flange portion 110 and the stopper ring 130 are accommodated is the flange portion 110 or the concave portion 112 of the flange portion 110 in the ball holding ring 120 and the stopper ring. It can also be said that 130 is embedded.

A4. Nut attachment assembly:
FIG. 4 is an explanatory view showing an assembly mode of the nut attachments 100 and 100a. Fig.4 (a) has shown the state which assembled the nut attachment 100 as 1st Embodiment. FIG.4 (b) has shown the modification assembled in the different aspect using the same member as the member which comprises the nut attachment 100 of 1st Embodiment. FIG. 4A and FIG. 4B show a state in which the nut attachments 100 and 100a are viewed from the mounting surface side, respectively. 4 (a) and 4 (b), the stopper ring 130 is seen through in order to clearly show the assembly mode of the nut attachments 100 and 100a. As described above, the center hole 118 provided in the flange portion 110, the center hole 128 provided in the annular portion 121 of the ball holding ring 120, and the center hole 138 provided in the stopper ring 130 have an inner diameter. Since they are substantially the same and are formed around the central axis C (FIG. 2), they overlap on the same axis. Therefore, below, these center holes 118, 128, and 138 are also handled as a single center hole 108 formed in the nut attachments 100 and 100a.

  The nut attachment 100 is assembled by attaching the ball holding ring 120 to which the ball 140 is attached, the two springs 150, and the stopper ring 130 in this order to the attachment surface side of the recess 112 provided in the flange portion 110. As shown in FIG. 4A, the ball holding ring 120 has an annular portion 121 positioned inward of the extension portion 113 of the flange portion 110 and a projection 123 in a region where the extension portion 113 is not formed. To be positioned. The spring 150 is disposed between an end surface extending in the radial direction of the extending portion 113 and the protruding portion 123 in a region where the extending portion 113 is not formed. Then, the ball retaining ring 120 and the spring 150 are sandwiched between the flange portion 110 and the stopper ring 130 by attaching the stopper ring 130 so as to be disposed inside the concave portion 112 formed in the flange portion 110. It is. Thereby, the drop-off of the ball holding ring 120 and the spring 150 is suppressed. Further, by arranging the spring 150 as shown in FIG. 4A, the ball holding ring 120 and the ball 140 attached to the ball holding ring 120 are viewed from the mounting surface side as shown by the arrows. It is biased to rotate clockwise. In addition, since it is clear from FIG. 4 that the rotation by the urging is centered on the central axis C (FIG. 2) and is relative to the flange portion 110, in this specification and the like, the urging is performed. The center of rotation and the reference for rotation are not mentioned.

  In the nut attachment 100a shown in FIG. 4B, the positional relationship between the ball holding ring 120 and the spring 150 is opposite to that of the nut attachment 100 shown in FIG. Therefore, the ball holding ring 120 and the ball 140 attached to the ball holding ring 120 are urged to rotate counterclockwise as viewed from the attachment surface side, as indicated by the arrows. The other points are the same as the nut attachment 100 shown in FIG.

A5. The action of biasing the ball retaining ring and ball:
FIG. 5 is an explanatory diagram for explaining the action of urging the ball holding ring 120 and the ball 140. FIG. 5 shows a cross section of the transmission mechanism 10 cut along a plane parallel to the flat portions 111 and 211 (FIG. 2) provided on the flange portions 110 and 210 through the central axis C. In FIG. 5, the arrows indicate the direction of urging the ball holding ring 120 and the ball 140 and the direction of the load applied to each part.

  As described above, in the nut attachment 100 of the first embodiment, the ball holding ring 120 and the ball 140 attached to the ball holding ring 120 are biased so as to rotate clockwise as viewed from the mounting surface side. The Further, the screw groove 309 formed in the screw shaft 300 constitutes four right-hand threads. Therefore, the urged ball 140 moves in the direction from the sliding nut 200 side toward the nut attachment 100 side. At this time, since the nut attachment 100 and the sliding nut 200 are fixed, the movement of the ball 140 in the load direction is restricted, so that the ball 140 contacts the bottom surface of the concave portion 112 of the flange portion 110. As a result, a load in the direction from the nut attachment 100 side toward the sliding nut 200 side (downward in FIG. 5) is applied to the ball 140 from the bottom surface of the recess 112. By applying a load to the ball 140 in this way, a load in the direction from the nut attachment 100 side to the sliding nut 200 side, which is the same direction as the load applied to the ball 140, is applied from the ball 140 to the thread groove 309.

  On the other hand, as a reaction of the load applied to the ball 140 from the bottom surface of the recess 112, a load in the direction from the sliding nut 200 side to the nut attachment 100 side (upward in FIG. 5) is applied from the ball 140 to the bottom surface of the recess 112. As described above, since the nut attachment 100 and the sliding nut 200 are fixed, a load in a direction from the sliding nut 200 side toward the nut attachment 100 side is also applied to the sliding nut 200, and the female thread portion 220 of the sliding nut 200 is applied. A load in a direction from the sliding nut 200 side to the nut attachment 100 side, which is the same direction, is also applied to the thread groove 309 from the projecting portion 221 provided in the nut.

  Thus, in the nut attachment 100 of the first embodiment, the ball holding ring 120 and the ball 140 attached to the ball holding ring 120 are urged so as to rotate clockwise as viewed from the attachment surface side. Therefore, a load is applied to each of the ball 140 and the protruding portion 221 so as to bring the ball 140 and the protruding portion 221 closer to each other. As shown in FIG. 4B, when the ball holding ring 120 and the ball 140 are urged counterclockwise as viewed from the mounting surface side, the ball 140 and the protruding portion 221 are respectively A load is applied so as to separate the ball 140 and the protruding portion 221 from each other.

A6. Backlash reduction:
FIG. 6 is an explanatory diagram showing a state in which backlash is reduced by applying a load to the ball 140 and the protruding portion 221. 6A to 6C are enlarged views of the cross section of the ball 140 constituting the nut attachments 100 and 100a (FIG. 4), the female thread 220 constituting the sliding nut 200 (FIG. 5), and the screw shaft 300. FIG. I draw.

  As shown in FIG. 6A, when the ball 140 and the protruding portion 221 of the female screw portion 220 are not subjected to a load that brings the ball 140 and the protruding portion 221 close to or away from each other, the ball 140 and the screw shaft There are gaps between the 300 screw grooves 309 and between the protrusions 221 and the screw grooves 309. Therefore, when the rotation of the screw shaft 300 is reversed, backlash corresponding to the rotation angle corresponding to the formed gap occurs.

  On the other hand, as shown in FIG. 6B, when a load is applied to each of the ball 140 and the protruding portion 221 so as to bring the ball 140 and the protruding portion 221 closer to each other, And the position of the protruding portion 221 on the ball 140 side, the ball 140 and the protruding portion 221 are kept in contact with the screw groove 309 of the screw shaft 300. Therefore, even when the rotation of the screw shaft 300 is reversed and the traveling direction of the screw groove 309 is switched to the opposite direction, either the ball 140 or the protruding portion 221 is always moved by the screw groove 309. Is reduced.

  Similarly, as shown in FIG. 6C, when a load is applied to each of the ball 140 and the protruding portion 221 so as to separate the ball 140 and the protruding portion 221 from each other, The ball 140 and the protruding portion 221 and the screw groove 309 of the screw shaft 300 are kept in contact with each other at a position opposite to the ball 140 side of the protruding portion 221. Therefore, even when the rotation of the screw shaft 300 is reversed and the traveling direction of the screw groove 309 is switched to the opposite direction, either the ball 140 or the protruding portion 221 is always moved by the screw groove 309. Is reduced.

A7. Variations of the nut attachment configuration:
FIG. 7 is an explanatory view showing a modification of the configuration of the nut attachment. The nut attachments 100b and 100c shown in FIG. 7A and FIG. 7B are different from the nut attachment 100 of the first embodiment in the configuration for biasing the ball holding rings 120b and 120c and the ball 140. In addition, also in the nut attachments 100b and 100c shown in FIG. 7A and FIG. 7B, since there is a part common to the nut attachment 100 of the first embodiment, the common part is the same as that of the first embodiment. The description is omitted.

  A nut attachment 100b shown in FIG. 7A uses a cylindrical elastic member 150b instead of the spring 150 (FIG. 4) to urge the ball holding ring 120b and the ball 140. The elastic member 150b can be formed of various materials that can be elastically deformed, such as rubber and sponge. The flange portion 110b of the nut attachment 100b is formed with a concave portion 112b having an inner surface substantially circular and extending outward at an equiangular position (hereinafter also referred to simply as “equal angular position”) with the central axis as an axis. Four extending portions 113b extending toward the mounting surface are provided on the bottom surface of the recess 112b. The annular portion 121b of the ball holding ring 120b is provided with a notch 123b that extends inward from the outer peripheral portion in place of the protrusion 123 (FIG. 4). A region extending outward in the recess 112b, a surface facing the adjacent extension 113b, and a notch 123b provided in the annular portion 121b are substantially the same as the inner surface so that the elastic member 150b can be inserted. It is formed to be circular. It should be noted that the shape of the elastic member and the shape of the inner surface of the region into which the elastic member is inserted can be appropriately changed.

  In FIG. 7A, the ball attachment 140b is fixed to the sliding nut 200 (FIG. 1), and the ball 140 is deformed so that the elastic member 150b is deformed when the nut attachment 100b and the sliding nut 200 are attached to the screw shaft 300. The position of is adjusted. Thereby, the ball holding ring 120b and the ball 140 are urged in the clockwise direction when viewed from the mounting surface side. The position of the ball 140 can be adjusted as appropriate by adjusting the angle formed between the ball receiving hole 122 into which the ball 140 is fitted and the notch 123b with reference to the central axis. It is also possible to adjust the position of the ball 140 as appropriate so as to urge the ball 140 counterclockwise as viewed from the mounting surface side. Thus, also in the nut attachment 100b shown to Fig.7 (a), it can urge | bias so that the ball | bowl 140 may be rotated seeing from the attachment surface side. Therefore, even if the nut attachment 100b shown in FIG. 7A is used, the backlash of the transmission mechanism can be reduced as in the case of the nut attachment 100 of the first embodiment. As is clear from FIG. 7A, the ball holding ring 120b is formed in an annular shape as a whole.

  The nut attachment 100c shown in FIG. 7B uses a spiral spring 150c instead of the coiled spring 150 (FIG. 4) to urge the ball holding ring 120c and the ball 140. Both ends of the spiral spring 150c are bent in one direction orthogonal to the main plane of the spiral spring 150c. The flange portion 110c of the nut attachment 100c is provided with a concave portion 112c having a shallow outer peripheral portion 113c so that the inner surface forms two concentric circles. The outer peripheral portion 113c is provided with a spring insertion hole 115c for inserting one end of the spiral spring 150c. The annular part 121c of the ball holding ring 120c is not provided with the protrusion 123 (FIG. 4) or the notch 123b (FIG. 7A), and its outer periphery is circular. Similarly to the outer peripheral portion 113c, the annular portion 121c is provided with a spring insertion hole 125c for inserting the other end of the spiral spring 150c. As described above, the spring insertion holes 115c and 125c are provided in the outer peripheral portion 113c and the annular portion 121c, and the end portions of the spiral spring 150c are inserted into the spring insertion holes 115c and 125c, whereby the ball holding ring 120c and the ball 140 are attached to the mounting surface. It is energized clockwise as seen from the side. In addition, in the nut attachment 100c shown in FIG.7 (b), the stopper ring 130 is abbreviate | omitted so that a deformation | transformation of the spiral spring 150c may not be suppressed. Therefore, in the nut attachment 100c, it is preferable to urge the ball holding ring 120c and the ball 140 in the clockwise direction when viewed from the mounting surface side. Thus, also in the nut attachment 100c shown in FIG.7 (b), it can urge | bias so that the ball | bowl 140 may be rotated. Therefore, the backlash of a transmission mechanism can be reduced similarly to the nut attachment 100 of 1st Embodiment. As is apparent from FIG. 7B, the ball holding ring 120c is formed in an annular shape as a whole.

  When energizing the ball 140 using the spiral spring 150c, by providing a plurality of spring insertion holes in the outer peripheral portion of the flange portion or the annular portion of the ball holding ring, and changing the spring insertion hole into which the end portion is inserted, The strength of the urging force to rotate the ball 140 can be adjusted. In this respect, it is preferable to urge the ball 140 to rotate using the spiral spring 150c. In this case, the shape of the spiral spring 150c changes in a state where the nut attachment 100c is not attached to the sliding nut 200 (FIG. 1), that is, in a state shown in FIG. 7B. Therefore, it can be said that the configuration is such that the strength of the force for urging the ball 140 can be adjusted by changing the shape of the spiral spring 150c. When the force for urging the ball 140 is increased, the force required to rotate the nut attachment 100c and the sliding nut 200 (FIG. 1) relative to the screw shaft 300 is increased. On the other hand, when the force for urging the ball 140 is weakened, the backlash reduction effect is diminished. Therefore, by adjusting the strength of the force that urges the ball 140, the strength of the force that urges the ball 140 is appropriately adjusted according to the purpose of use of the transmission mechanism, and the operation of the transmission mechanism is more appropriate. It becomes possible to adjust to. On the other hand, a spiral spring having a bent end is not always easy to make, and it is not always easy to change the urging direction of the ball 140. In these respects, it is preferable to urge the ball 140 to rotate by other methods.

  As described above, in the first embodiment, in the nut attachment 100 fixedly attached to the sliding nut 200, the ball 140 meshing with the thread groove 309 of the screw shaft 300 is rotated around the central axis C (FIG. 1). It is energized to let you. In other words, the ball 140 that constitutes the meshing portion that meshes with the thread groove 309 of the screw shaft 300 is applied by the biasing portion (spring 150) so as to rotate relative to the sliding nut 200 to which the nut attachment 100 is attached. It is energized. Therefore, a load can be applied to each of the ball 140 and the protruding portion 221 of the sliding nut 200 such that the ball 140 and the protruding portion 221 approach or separate from each other. Thereby, even when the rotation of the screw shaft 300 is reversed and the traveling direction of the screw groove 309 is switched to the opposite direction, either the ball 140 or the protruding portion 221 is always moved by the screw groove 309. Therefore, backlash can be reduced more stably.

  In the first embodiment, the ball 140 is urged to rotate, so that a load is applied to the ball 140 and the protruding portion 221 of the sliding nut 200 so that the ball 140 and the protruding portion 221 approach or separate from each other. Yes. Therefore, even when the ball 140, the protrusion 221 or the screw shaft 300 is worn, it is possible to continue to apply a load to the ball 140 and the protrusion 221. Further, the load applied to the ball 140 and the protruding portion 221 is applied by urging the ball 140 so that the ball 140 rotates with respect to the flange portion 110 fixed to the sliding nut 200. Even when a load that causes the nut attachment 100 and the sliding nut 200 to approach or separate from each other is applied to the sliding nut 200, the load applied to the ball 140 and the protruding portion 221 is maintained, and the effect of reducing backlash is attenuated. Is suppressed.

  Further, in the first embodiment, the function of eliminating the backlash is realized by the concave portion 112 of the flange portion 110 and the ball holding ring 120 and the stopper ring 130 embedded in the concave portion 112. For this reason, it is possible to change the shape of the flange portion of the nut attachment by simply changing the shape of the outer side of the recess 112, so that it is easier to manufacture a nut attachment corresponding to a sliding nut having a different shape of the flange portion. It becomes possible. And the change of the shape of the transmission mechanism by attaching a nut attachment can be suppressed by making the outer edge of each flange part of a nut attachment and a sliding nut into the same shape. Therefore, it becomes easier to reduce the backlash of the existing transmission mechanism using a sliding nut.

  In the first embodiment, the ball holding ring 120 and the stopper ring 130 for realizing the function of eliminating the backlash are in a state of being embedded in the concave portion 112 of the flange portion 110. Therefore, the nut attachment 100 can be made thinner more easily. And the change of the shape of the transmission mechanism 10 by attaching the nut attachment 100 can be suppressed by making the nut attachment 100 thin. Therefore, it becomes easier to reduce the backlash of the existing transmission mechanism using the sliding nut 200.

B. Second embodiment:
FIG. 8 is an explanatory diagram showing the configuration of the nut attachment 100d of the second embodiment. In the nut attachment 100d of the second embodiment, the extending portion 113d provided on the flange portion 110d and the protruding portion 123d of the ball holding ring 120d are arranged at positions shifted from the nut attachment 100 of the first embodiment. A point in which the spring 150d is arranged linearly, a point in which the screw hole 116d is provided in the flange portion 110d, and a screw screw 160d that is screwed into the screw hole 116d. It is different from the nut attachment 100 of the embodiment. Other points are the same as the nut attachment 100 of the first embodiment.

  As shown in FIG. 8, in the nut attachment 100d of the second embodiment, a screw hole 116d penetrating from the flat portion 111d toward the outer peripheral portion of the recess 112d is formed. The screw hole 116d is formed so that the screw 160d to be screwed is positioned near the bottom of the recess 112d. And the spring 150d is arrange | positioned between the front-end | tip of the scissors screw 160d screwed in the screw hole 116d, and the end surface extended in the radial direction of the expansion part 113d. When the scissors screw 160d is screwed in this state, the spring 150d is compressed and the force applied to the protrusion 123d is increased. On the other hand, when the scissors screw 160d is pulled out, the spring 150d is extended, and the force applied to the protrusion 123d is weakened. Therefore, it becomes easier to adjust the urging force to rotate the ball holding ring 120d and the ball 140 clockwise as viewed from the mounting surface side. It is to be noted that energizing is performed in a state where the nut attachment 100d is not attached to the sliding nut 200 (FIG. 1), that is, in a state shown in FIG. 8, by screwing the screw 160d or removing the screw 160d. The shape of the part (spring 150d) changes. Therefore, it can be said that the net attachment 100d of the second embodiment is also configured to be able to adjust the strength of the force for urging the ball 140 by changing the shape of the urging portion. In the example of FIG. 8, the spring 150d is used as the urging portion that urges the ball holding ring 120d and the ball 140. However, an elastic member may be used as the urging portion instead of the spring 150d. is there. Even in this case, the elastic member (the urging portion) is deformed by screwing the rivet screw 160d or removing the rivet screw 160d. Therefore, by changing the shape of the urging portion, the ball 140 is removed. It can be said that it is possible to adjust the strength of the urging force.

  In the nut attachment 100d of the second embodiment, the urging force for urging the ball 140 to rotate can be changed by operating the scissors screw 160d protruding from the flange portion 110d. Therefore, when attaching the nut attachment 100d and the sliding nut 200 to the screw shaft 300, it is possible to make the attachment of the nut attachment 100d and the sliding nut 200 to the screw shaft 300 easier by reducing the biasing force. On the other hand, after the nut attachment 100d and the sliding nut 200 are attached to the screw shaft 300, the urging force is increased, so that the ball 140 and the protruding portion 221 of the sliding nut 200 are added, and the ball 140 and the protruding portion 221 are mutually connected. The load that approaches or separates can be increased. Therefore, the backlash of the transmission mechanism can be more reliably reduced. Furthermore, in the nut attachment 100d of the second embodiment, the urging force applied to the ball 140 can be changed. Therefore, the urging force applied to the ball 140 is appropriately adjusted according to the purpose of use of the transmission mechanism, and the transmission mechanism It becomes possible to make the operation more appropriate. In these respects, the second embodiment is preferable to the first embodiment. On the other hand, the first embodiment is preferable to the second embodiment in that the configuration of the nut attachment 100 becomes simpler.

C. Third embodiment:
FIG. 9 is an exploded perspective view showing the configuration of the nut attachment 100e in the third embodiment. The nut attachment 100e includes an adjustment member 170e and a fixing ring 180e in addition to a flange portion 110e, a spherical elastic member 150e, a ball holding ring 120e, a ball 140, and a stopper ring 130. As shown in FIG. 9, these members 180e, 110e, 170e, 150e, 120e, and 130 are assembled in the direction of the central axis C to form a nut attachment 100e.

  The flange portion 110e of the third embodiment is the same as the flange portion 110 of the first embodiment shown in FIG. 3 (a), in that the diameter of the center hole 118e is large, and from the bottom of the recess 112 to the mounting surface side. The difference is that the extending portion 113 is not provided. In addition, the ball holding ring 120e of the third embodiment has a thin thickness in the central axis C direction, and is formed so that the ball receiving hole 122e penetrates in the central axis C direction, and the protrusion 123e. Is different from the ball holding ring 120 of the first embodiment in that it is formed in a fan shape.

  The adjustment member 170e has a cylindrical cylindrical portion 171e whose outer diameter is slightly smaller than the inner diameter of the center hole 118e of the flange portion 110e, and a flat plate-like plate shape whose outer diameter is slightly smaller than the inner diameter of the concave portion 112e of the flange portion 110e. It has a portion 172e and a fan-like elongated portion 173e extending from the plate-like portion 172e to the mounting surface side. The extending part 173e is formed so that the outer diameter is substantially the same as the outer diameter of the plate-like part 172e and the inner diameter is slightly larger than the outer diameter of the annular part 121e of the ball holding ring 120e. Therefore, the adjustment member 170e and the ball holding ring 120e are relatively rotatable around the central axis C within a certain range, and the adjustment member 170e and the ball holding ring 120e are centered with respect to the flange portion 110e. It can freely rotate around the axis C.

  The fixing ring 180e is an annular member having an outer diameter larger than the inner diameter of the center hole 118e of the flange portion 110e. A central hole 188e having an inner diameter substantially the same as the outer diameter of the cylindrical portion 171e of the fixing member 170e is formed in the fixing ring 180e. On the inner surface of the center hole 188e, a female screw that meshes with a male screw formed on the outer surface of the cylindrical portion 171e of the adjusting member 170e is formed.

  As shown in FIG. 9, by making the cylindrical portion 171e of the adjusting member 170e sufficiently long in the direction of the central axis C, the cylindrical portion 171e is projected to the opposite side of the mounting surface through the center hole 118e of the flange portion 110e. Then, the adjustment member 170e and the fixing ring 180e are connected to each other by tightening the male screw formed on the outer surface of the cylindrical portion 171e and the screw formed on the inner surface of the center hole 188e of the fixing ring 180e. It is fixed to the part 110e.

  FIG. 10 is an explanatory view showing a state in which the ball holding ring 120e is biased in the third embodiment, and the positional relationship between the flange portion 110e, the adjustment member 170e, the elastic member 150e, the ball holding ring 120e, and the ball 140. Is shown. FIG. 10A shows a state where the nut attachment 100e is attached to the sliding nut 200 and the screw shaft 300 is passed through the nut attachment 100e and the sliding nut 200, that is, a state where the transmission mechanism is assembled, as in FIG. FIG. 10B shows a state where the ball holding ring 120e is further urged with the transmission mechanism assembled.

  As shown in FIG. 10A, when the nut attachment 100e is assembled, the elastic member 150e is positioned between the extending portion 173e of the adjusting member 170e and the protruding portion 123e of the ball holding ring 120e. Then, when the adjusting member 170e is rotated clockwise as viewed from the mounting surface side as indicated by the arrow, the extending portion 173e of the adjusting member 170e, the elastic member 150e, and the protruding portion 123e of the ball holding ring 120e come into contact with each other. .

  As is clear from FIG. 10A, when the adjusting member 170e and the ball holding ring 120e are rotated with each other in a state where the elastic member 150e is not disposed, the extending portion 173e of the adjusting member 170e and the ball holding ring 120e are rotated. The protruding portion 123e contacts. Therefore, the extending portion 173e and the protruding portion 123e can also be called contact portions that can come into contact with each other when the adjusting member 170e and the ball holding ring 120e are rotated with each other in a state where the elastic member 150e is removed. In general, the adjustment member and the ball holding ring need only be configured so that they can come into contact with each other when the adjustment member and the ball holding ring are rotated with the elastic member removed. It is also possible to change various shapes of the portion and the protrusion.

  In this state, when the adjustment member 170e is further rotated clockwise as viewed from the mounting surface side, the elastic member 150e is deformed. Thereby, the ball holding ring 120e is urged clockwise as viewed from the rotation direction of the adjustment member 170e, that is, the mounting surface side, as indicated by an arrow. Thereby, the ball 140 accommodated in the ball accommodation hole 122e of the ball holding ring 120e is urged clockwise as viewed from the mounting surface side. Then, in a state where the ball holding ring 120e is biased, the fixing ring 180e (FIG. 9) and the adjustment member 170e are tightened, and the adjustment member 170e is fixed to the flange portion 110e, whereby the ball holding ring 120e and the ball 140 are , Maintained in an energized state.

  In the nut attachment 100e of the third embodiment, after the transmission mechanism is assembled, the ball holding ring 120e and the ball 140 are rotated with respect to the flange portion 110e by rotating the adjustment member 170e with respect to the flange portion 110e. Can be energized as follows. Therefore, the transmission mechanism can be assembled more easily.

  Furthermore, in the nut attachment 100e of the third embodiment, the degree of deformation of the elastic member 150e can be adjusted by adjusting the rotation state of the adjustment member 170e in a state where the transmission mechanism is assembled. Therefore, since the force with which the ball holding ring 120e and the ball 140 are urged can be adjusted in the assembled state of the transmission mechanism, the urging force is appropriately adjusted according to the purpose of use of the transmission mechanism, and the operation of the transmission mechanism Can be adjusted more appropriately.

  In the example of FIGS. 9 and 10, the elastic member 150e is arranged so that the extending portion 173e, the elastic member 150e, and the protruding portion 123e contact in this order in the clockwise direction when viewed from the mounting surface side. However, the elastic member 150e may be arranged so that the extending portion 173e, the elastic member 150e, and the protruding portion 123e contact in this order counterclockwise when viewed from the mounting surface side. In this case, the ball holding ring 120e and the ball 140 are urged counterclockwise when viewed from the mounting surface side.

  9 and 10, the elastic member 150e has a spherical shape. However, the elastic member can be a rectangular parallelepiped or a fan surface, and a spring can be used instead of the elastic member 150e. It is. In general, an urging member such as an elastic member or a spring may be disposed between the extending portion 173e of the adjustment member 170e and the protrusion 123e (contact portion) of the ball holding ring 120e.

  Furthermore, in the third embodiment, the movement of the ball holding ring 120e and the ball 140 in the direction of the central axis C is restricted by the stopper ring 130 embedded in the recess 112e of the flange portion 110e. The movement of the ring 120e and the ball 140 in the direction of the central axis C may be restricted. For example, a plate member (stopper plate) having an outer edge shape that is substantially the same shape as the flange portion 110e, a through hole similar to the flange portion 110e, and a center hole similar to the stopper ring 130 is provided on the mounting surface side of the flange portion 110e. It may be attached. In this case, if the flange portion and the stopper plate are fixed with screws or the like, even when the nut attachment is handled alone, it is possible to prevent the portions of the nut attachment from separating and falling off.

D. Fourth embodiment:
FIG. 11 is an exploded perspective view showing a configuration of a nut attachment 100f in the fourth embodiment. In the nut attachment 100f of the fourth embodiment, instead of the fixing ring 180e, a fixing portion 117f is provided on the flange portion 110f, the cylindrical portion 171f of the adjustment member 170f, and the inner surface of the center hole 188e of the fixing ring 180e. The third embodiment is different from the nut attachment 100e of the third embodiment in that the screws formed in and are omitted. Other points are the same as in the third embodiment.

  As described above, the flange portion 110f of the fourth embodiment is provided with the annular fixing portion 117f on the side opposite to the mounting surface side. The fixing portion 117f is formed with a screw hole 116f in a direction from the flat portion 111e toward the central axis C and a direction rotated 90 degrees about the direction and the central axis C. The adjusting member 170f can be fixed to the flange portion 110f by screwing a set screw such as a coffin screw into the screw holes 116f in a state where the cylindrical portion 171f is passed through the center hole 118f of the flange portion 110f.

  As described above, since the adjustment member 170f can be fixed to the flange portion 110f, also in the nut attachment 100f of the fourth embodiment, the adjustment member 170f is attached to the flange portion 110f as in the third embodiment shown in FIG. The ball holding ring 120e and the ball 140 can be maintained in a biased state by fixing the adjustment member 170f to the flange portion 110f in a state where the elastic member 150e is deformed while rotating.

  Therefore, also in the fourth embodiment, after the transmission mechanism is assembled, the ball holding ring 120e and the ball 140 can be urged to rotate with respect to the flange portion 110f, so that the transmission mechanism can be assembled more easily. It can be carried out. Further, in the assembled state of the transmission mechanism, the force with which the ball holding ring 120e and the ball 140 are urged can be adjusted, so that the urging force is appropriately adjusted according to the purpose of use of the transmission mechanism to Can be adjusted more appropriately.

  Thus, in the fourth embodiment, the adjustment member 170f can be fixed to the flange portion 110f by screwing the set screw into the screw hole 116f formed in the fixing portion 117f of the flange portion 110f. Therefore, when the adjustment member 170f is fixed to the flange portion 110f, a force that rotates with respect to the flange portion 110f is suppressed from being applied to the adjustment member 170f, and the urging force applied to the ball holding ring 120e and the ball 140 is more accurately detected. Can be adjusted. In this respect, the fourth embodiment is preferable to the third embodiment. On the other hand, the third embodiment is preferable to the fourth embodiment in that the configuration of the nut attachment 100e can be simplified.

  In addition, in the nut attachment 100f of 4th Embodiment, although the fixing | fixed part 117f with which the screw hole 116f was provided in the flange part 110f is provided, it is also possible to abbreviate | omit the fixing | fixed part 117f. In this case, the adjustment member 170f can be fixed to the flange portion by providing a screw hole in the flat portion 111 of the flange portion and screwing a set screw such as a scissors screw into the screw hole.

  Also in the fourth embodiment, the adjustment member 170f is protruded on the side opposite to the mounting surface of the flange portion 110f by making the cylindrical portion 171f of the adjustment member 170f sufficiently long in the central axis C direction. It is not necessary to project the member 170f to the side opposite to the mounting surface of the flange portion 110f. In this case, the side opposite to the mounting surface of the cylindrical portion is shaped to be applied to the tool (for example, a recess formed in the direction of the mounting surface), and the adjustment member is attached to the flange portion by using a tool that matches the shape. Can be rotated. However, the adjusting member 170f is rotated with respect to the flange portion 110f and the ball holding ring 120e and the ball 140 can be biased more easily, so that the adjusting member 170f protrudes on the opposite side of the mounting surface of the flange portion 110f. Preferably.

E. Variations:
The present invention is not limited to the above-described embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

E1. Modification 1:
In each of the above embodiments, the nut attachments 100, 100a, 100b, 100c, 100d, 100e, and 100f are fixed to the sliding nut 200. However, in place of the sliding nut 200, various types used as a transmission mechanism such as a ball nut. It is also possible to attach the nut attachments 100, 100a, 100b, 100c, 100d, 100e, and 100f to the nuts (transmission nuts). Even in this case, a load can be applied to the meshing portion of the transmission nut that meshes with the screw groove 309 of the screw shaft 300 and the ball 140 so as to bring the meshing portion and the ball 140 close to or away from each other. It is possible to reduce backlash.

E2. Modification 2:
In each of the above embodiments, in the nut attachments 100, 100a, 100b, 100c, 100d, 100e, 100f, the balls 140 fitted in the ball holding rings 120, 120b, 120c, 120d, 120e are inserted into the screw grooves 309 of the screw shaft 300. Although engaged, a protrusion that engages with the thread groove 309 may be provided on a ring that is urged to rotate in the same manner as the ball holding rings 120, 120 b, 120 c, 120 d, and 120 e. In this case, the ball 140 is prevented from falling off when the nut attachments 100, 100a, 100b, 100c, 100d, 100e, and 100f are handled, so that the nut attachment can be handled more easily. However, when the screw shaft 300 is rotated, the friction between the nut attachments 100, 100a, 100b, 100c, 100d, 100e, and 100f and the screw shaft 300 is further reduced, and the protrusions constituting the screw shaft 300 and the meshing portion. The ball 140 fitted in the ball holding rings 120, 120 b, 120 c, 120 d, and 120 e is meshed with the screw groove 309 in that the wear of the ball can be suppressed and the power transmission efficiency can be further increased. Is preferred.

E3. Modification 3:
In each of the above embodiments, the screw shaft 300 provided with the screw grooves 309 constituting the four threads is used, but the number of threads of the screw shaft can be variously changed. In this case, the number of balls fitted into the ball holding ring is changed according to the number of threads of the screw shaft. The number of balls can be any number of 1 or more, but is preferably 3 or more in order to suppress the inclination of the ball holding ring. Further, the number of balls is preferably 4 or more in order to further improve the durability of the balls and the like. Further, it is preferable that the positions of the balls and the ball receiving holes of the ball holding ring are equiangular positions in order to suppress the inclination of the ball holding ring. When the number of threads on the screw shaft is different from the number of balls, the position of the ball is adjusted along the direction of the central axis C according to the lead of the screw shaft.

E4. Modification 4:
In each of the above embodiments, the present invention is applied to the nut attachments 100, 100a, 100b, 100c, 100d, 100e, and 100f that are fixed to the sliding nut 200. However, the present invention is not limited to the thread groove provided on the screw shaft. It is also possible to apply to a nut assembly that functions as an integral transmission nut that meshes with the nut. The nut assembly may have two nuts, and the two nuts may be biased so as to rotate relative to the central axis.

  FIG. 12 is an explanatory diagram showing a configuration of the transmission mechanism 20 using the nut assembly 21 as an example. The transmission mechanism 20 includes a nut assembly 21 and a screw shaft 300g formed with a screw groove 309g constituting two right-hand screws. The nut assembly 21 includes two ball nuts 400 and 500 and a sleeve 700 that accommodates these ball nuts 400 and 500. The first ball nut 400 has a substantially cylindrical tubular portion 410 and a ball 420. Similarly, the second ball nut 500 has a substantially cylindrical tubular portion 510 and a ball 520.

  The cylindrical portions 410 and 510 constituting the first and second ball nuts 400 and 500 are provided with ball holes 418 and 518 penetrating from the outside toward the central axis D, respectively. The balls 420 and 520 are inserted into the ball holes 418 and 518 so that a part of the balls 420 and 520 protrudes inward as in the above embodiments. The ball holes 418 and 518 may have an inner diameter that is smaller on the inner side so as to prevent the balls 420 and 520 from dropping off toward the central axis D. A central hole 419 for passing the screw shaft 300g is formed in the cylindrical portion 410 of the first ball nut 400. Although not shown, the cylindrical portion 510 of the second ball nut 500 is also formed with a center hole for passing the screw shaft 300g.

  The sleeve 700 is a bottomed and substantially cylindrical member, and the sleeve 700 has a center hole 709 for allowing the screw shaft 300g to pass therethrough and a nut accommodation hole 708 for accommodating the two ball nuts 400 and 500. Is provided. By accommodating the ball nuts 400 and 500 in the nut accommodation holes 708, the balls 420 and 520 constituting the ball nuts 400 and 500 are restricted from moving outward and are held in the ball holes 418 and 518. A through hole 707 that penetrates in the direction of the central axis D is formed at the bottom of the sleeve 700. The sleeve 700 and the first ball nut 400 are fixed by screwing a bolt (not shown) into the screw hole 417 formed in the cylindrical portion 410 of the first ball nut 400 through the through hole 707. . In the example of FIG. 12, the sleeve 700 is substantially cylindrical, but a flange or the like may be provided for fixing the driving object to the sleeve.

  In the nut assembly 21 shown in FIG. 12, a concave portion 411 is provided at an end portion of the cylindrical portion 410 constituting the first ball nut 400 on the second ball nut 500 side. A convex portion 511 is provided at the end of the cylindrical portion 510 constituting the second ball nut 500 on the second ball nut 100 side. The elastic member 600 is disposed in the gap formed by the concave portion 411 and the convex portion 511. Thereby, the second ball nut 500 is urged so as to rotate in the direction indicated by the arrow with respect to the first ball nut 400. This urging direction corresponds to the counterclockwise direction when viewed from the mounting surface side in each of the above embodiments. Therefore, a load is applied from the thread groove 309g to the two ball nuts 400, 500 so as to bring the ball nuts 400, 500 closer to each other, and the second ball nut 500 is prevented from falling off the nut assembly 21. Since the two ball nuts 400 and 500 are urged by the urging portion (elastic member 600) so as to relatively rotate, the balls 420 and 520 protruding inward from the cylindrical portions 410 and 510 are provided. Since a load is applied to a part (that is, a meshing portion that meshes with the screw groove 309e) such that the meshing portions are separated from each other, backlash in the transmission mechanism 20 is reduced as in the above embodiments.

  In the example of FIG. 12, the elastic member 600 is used as the urging unit. However, instead of the elastic member 600, a spring can be used as the urging unit. In the example of FIG. 12, ball nuts 400 and 500 are used as two nuts that mesh with the thread groove 309g of the screw shaft 300g. However, at least one of these ball nuts 400 and 500 is used as a sliding nut or the like. It is possible to replace with other types of nuts. However, it is possible to reduce the friction between the nut and the screw shaft 300g when the screw shaft 300g is rotated, to suppress wear of the screw shaft 300g and the nut, and to increase the power transmission efficiency. Therefore, it is preferable that at least one of the two nuts is a ball nut. When using nuts other than the ball nut as the two nuts engaged with the thread groove 300g, the sleeve 700 can be omitted. However, it is preferable to provide a sleeve that covers at least the urging portion in that the urging portion can be prevented from falling off.

  In the example of FIG. 12, loads are applied to the meshing portions of the ball nuts 400 and 500 so that the meshing portions are separated from each other. It is also possible to apply a load to the meshing parts so that the meshing parts approach each other. However, in this case, in order to prevent the second ball nut 500 from dropping from the nut assembly 21, a drop-off restricting member such as a lid is added to the end of the sleeve on the second ball nut 500 side.

DESCRIPTION OF SYMBOLS 10 ... Transmission mechanism 20 ... Transmission mechanism 21 ... Nut assembly 100, 100a, 100b, 100c, 100d, 100e, 100f ... Nut attachment 108 ... Center hole 110, 110b, 110c, 110d, 110e, 110f ... Flange part 111, 111d ... Flat part 112, 112b, 112c, 112d, 112e ... Recess 113, 113b, 113d ... Elongation part 113c ... Outer peripheral part 115c ... Spring insertion hole 116d, 116f ... Screw hole 117f ... Fixing part 118, 118e, 118f ... Center hole 119 ... through holes 120, 120b, 120c, 120d, 120e ... ball holding rings 121, 121b, 121c, 121d, 121e ... annular portions 122, 122e ... ball receiving holes 123, 123d, 123e ... projections 123b ... notches 12 c ... Spring insertion hole 128, 128e ... Center hole 130 ... Stopper ring 138 ... Center hole 140 ... Ball 150, 150d ... Spring 150b, 150e ... Elastic member 150c ... Spiral spring 160d ... Thumb screw 170e, 170f ... Adjustment member 171e, 171f ... Cylindrical part 172e ... Plate-like part 173e ... Extension part 178e ... Center hole 180e ... Fixing ring 188e ... Center hole 200 ... Slip nut 210 ... Flange part 211 ... Flat part 218 ... Center hole 220 ... Female thread part 221 ... Projection part 228 ... Center hole 300 ... Screw shaft 300g ... Screw shaft 309 ... Screw groove 309g ... Screw groove 400 ... Ball nut 410 ... Cylindrical part 411 ... Recess 420 ... Ball,
417 ... Screw hole 418 ... Ball hole 419 ... Center hole 500 ... Ball nut 510 ... Cylindrical part 511 ... Convex part 518 ... Ball hole 520 ... Ball,
600 ... Elastic member 700 ... Sleeve 707 ... Through hole 708 ... Nut receiving hole 709 ... Center hole

Claims (9)

In a feed screw mechanism having a screw shaft formed with a thread groove and a transmission nut meshing with the thread groove, a nut attachment attached to the transmission nut,
A nut fixing portion for fixing the nut attachment to the transmission nut;
A meshing portion meshing with the thread groove;
A biasing portion that biases the meshing portion so as to rotate the meshing portion with respect to the nut fixing portion;
Comprising
Nut attachment. The nut attachment according to claim 1,
The meshing part is
With the ball,
Holding the ball rotatably, a ball holding ring formed in an annular shape;
Have
The ball is configured such that a part of the ball protrudes inward from the ball holding ring so as to mesh with the thread groove.
Nut attachment. The nut attachment according to claim 1 or 2,
The biasing part is
An adjustment member configured to be rotatable with respect to the nut fixing portion and fixed to the nut fixing portion;
A biasing member;
Have
The meshing portion is configured to be rotatable with respect to the nut fixing portion,
The adjustment member and the meshing portion each have a contact portion that can come into contact with each other when they are rotated with each other with the urging member removed.
The biasing member is disposed between the contact portion of the adjustment member and the contact portion of the meshing portion.
Nut attachment. The nut attachment according to claim 3,
The adjustment member protrudes from the side of the nut fixing portion opposite to the side on which the transmission nut is attached,
Nut attachment. The nut attachment according to claim 1 or 2,
The urging portion can change its shape in a state where the nut attachment is not attached to the transmission nut.
The nut attachment is configured to be able to adjust the strength of the force for biasing the meshing portion by changing the shape of the biasing portion.
Nut attachment. The nut attachment according to any one of claims 1 to 5,
The transmission nut has an object fixing portion for fixing an object to be driven,
The outer edge of the nut fixing part is formed in the same shape as the outer edge of the object fixing part,
Nut attachment. A lead screw device,
A screw shaft having a thread groove formed thereon;
A transmission nut meshing with the thread groove;
The nut attachment according to any one of claims 1 to 6,
Comprising
Lead screw device. A nut assembly that meshes with a screw groove provided on a screw shaft and constitutes a feed screw mechanism,
A first nut meshing with the thread groove;
A second nut engaged with the thread groove and attached to the first nut;
A biasing portion that biases the second nut so as to rotate the second nut relative to the first nut;
A nut assembly. A lead screw device,
A screw shaft having a thread groove formed thereon;
A nut assembly according to claim 8;
Comprising
Lead screw device.

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