JP2009079764A - Backbone type internal circulation ball screw unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal circulation ball lead screw having a small nut diameter, simple manufacturing processes and favorable smoothness during the reverse motion of balls. <P>SOLUTION: This sort of a backbone type internal circulation ball screw unit comprises a lead screw unit, a nut 2, a plurality of the balls 3, and a ball circulator having a S-shaped ball groove 4d. The circulator is mounted in the linear groove of the nut 2, and the linear groove has a bottom as an arch-curved face 2b. The passage bottom of the nut 2 has a cut-off portion smoothly transferred toward the arch-curved face 2b. The inside of the circulator having the ball groove 4d is directed to the lead screw unit, while the ball groove 4d is directed at its opening side to the arch-curved face 2b of the linear groove to form a ball return passage in cooperation with the arch-curved face 2b. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a ball screw unit drive, and more particularly to a ball lead screw unit having a ball circulator having an S-shaped ball groove.

  The ball lead screw unit is a drive unit in which a linear motion and a turning motion are alternately changed to each other. When the lead screw unit is rotating, the ball rotates in the passage with low friction loss, high driving efficiency, stable operation, without slow slowing speed and with high driving accuracy, into the passage. Move back and forth along. The nut in the lead screw unit is prestressed very firmly so as to completely eliminate the gap and increase the drive stiffness. Due to the features described above, ball lead screw units are gaining increasing importance in many industries.

  The nut of a ball lead screw unit usually has two ball circulation methods: an external circulation method in which the ball sometimes does not come into contact with the lead screw unit during circulation, and an internal circulation method in which the ball always keeps contact with the lead screw unit. There is. The internal circulatory structure typically has a circular or elliptical tension cage, and the external circulatory structure typically has a pipe.

  Feed tubes for external circulation can be manufactured in a simple manner and used widely. However, the diameter of the nut is small. Since the end of the curved tube is used as a ball barrier, the nut has low rigidity and wear resistance and a high noise level.

  Circular and elliptical internal circulation tension cages have a short return path, a compact structure, and high positioning reliability, rigidity and wear resistance. Despite the return path, the circulator is complex in structure, difficult to manufacture, and the connection between the circulator and the nut path is not smooth, which reduces the ball rolling stability. , Ball clogging and noise generation. Also, the ball must traverse the tooth tip of the lead screw unit during reverse operation in internal circulation mode, so the chamfer angle of the tooth tip of the lead screw unit affects the smoothness of the reverse ball.

  In order to solve problems such as the complicated structure of the internal circulation tension cage and the difficulty of the manufacturing process, an inventor has used a nut with a straight groove to position the protruding protruding end. And inserting a linear groove into the clearance of a bush-shaped tension cage (circulator) having a ball groove, inserting two positioning protruding ends into the nut screw passage, and the ball comprises a nut and a tension cage The ball is placed in a closed loop, the positioning protruding end of the tension cage is used to position on the spiral path of the nut, and the tension cage's free floating within a limited range. It is characterized by being aligned with the ball groove and thereby allowing the ball to roll back and forth within the closed loop of the nut. It discloses a slot mounted internal circulation ball screw unit according to (CN2341746Y). In this utility model patent, the problems of the complexity of the circulator structure and the difficulty of the manufacturing process are solved to a certain extent, but the following problems are still not solved. For example, a poor connection between the internal circulation tension cage and the nut passage affects ball rolling stability and the ball must traverse the tip of the lead screw unit during reverse operation in internal circulation mode. Therefore, the chamfering angle of the tooth tip of the lead screw unit affects the smoothness of the reverse ball.

  The present invention provides an internal circulation ball lead screw having a small nut diameter size, a simple manufacturing process, and good smoothness during reverse operation of the ball.

  In order to solve the above technical problems, the present invention has the following technical proposals. That is, the spine type internal circulation ball screw unit includes a lead screw unit, a nut, a plurality of balls, and a ball circulator having an S-shaped ball groove. On the inner surface of the nut, there is a longitudinal straight groove from which the helical passage of the nut is cut. The circulator is attached inside the straight groove of the nut. The bottom of the straight groove is an arcuate curved surface. The bottom of the nut passage transitions towards the arcuate curved surface at the part where it is cut off. The inner part of the circulator having a ball groove is directed to the lead screw unit, while the open side of the ball groove is directed to the arched curved surface of the linear groove and cooperates with the arched curved surface. Work to form a ball return path.

  The circulator of the spine type internal circulation ball screw unit preferably protrudes into the spiral passage of the lead screw unit at the ball inlet and outlet of the ball groove. The protruding portion at the ball inlet of the ball groove of the circulator is connected to the protruding portion at the ball outlet to form a spiral protruding beam.

  It is preferable that the protruding positioning posts of the spine type internal circulation ball screw unit are disposed at both ends of the circulator and inserted into the nut passage outside the ball loop.

  The arcuate curved surface of the spine-type internal circulation ball screw unit is in tangential contact with the bottom of the nut passage.

  The circulator of the spine-type internal circulation ball screw unit can be formed from engineering plastic.

  The longitudinal groove of the spine type internal circulation ball screw unit has a central angle of 75 ° to 95 °.

  The present invention combines the advantages of internal and external circulation.

  Compared to an external circulation pipe, the present invention uses a passage structure, a short return passage of a circulator, a compact structure, a small diameter size of a nut, and no end of a curved tube used as a ball barrier. Has the advantages of internal circulation, such as high rigidity and wear resistance, low noise level, high reliability in extreme environments.

  Compared to the internal circulation system, the present invention has the advantage of external circulation. 1) Since the circulator is a floating structure, it is not necessary to fix the circulator in the axial direction of the nut; the arcuate curved surface of the straight groove of the nut that is a part of the ball return passage is the portion where it is cut off The transition to the bottom of the nut passage is made, so that no step portion is formed and the smooth transition of the connection between the circulator and the nut passage becomes difficult, and the stability of the reverse operation of the ball is low. There are no such disadvantages. Further, in the present invention, the internal passage structure is applied so that the ball does not cross the tooth tip of the lead screw unit during the reverse operation, thereby the influence of the chamfering angle of the tooth tip of the lead screw unit with respect to the reverse ball. This eliminates the operating smoothness of the lead screw unit.

  Compared to ball lead screw units with circular and elliptical internal circulating tension cages, the present invention is simpler in construction and manufacturing and assembly process.

  If the technical proposal that the circulator protrudes into the helical passage of the lead screw unit at the ball inlet and outlet of the ball groove is used in the present invention, this technical proposal extends the length of the ball return passage. It is possible to avoid collision with the lead screw unit passage during the reverse operation of the ball and to improve the operational smoothness of the lead screw unit with the same circulator width.

  The accompanying drawings and examples are used to illustrate the present invention.

  As shown in FIG. 1, the spine type internal circulation ball screw unit includes a lead screw unit (1), a nut (2), a plurality of balls (3), and a circulator (4) having an S-shaped ball groove. And two wipers (5).

  As shown in FIGS. 7 and 9, there is a longitudinal linear groove (2a) that cuts out a spiral passage on the inner surface of the nut (2). The bottom of the straight groove (2a) is an arcuate curved surface (2b). The bottom (2c) of the passage of the nut (2) cut off by the straight groove (2a) is smoothly connected to the arched curved surface (2b) by a large circumferential angle R. If the bottom (2c) of the passage of the nut (2) is in direct tangential contact with the arcuate curved surface (2b) of the linear groove (2a), the ball can pass smoothly without using a circumferential angle.

The circulator (4) is like an animal spinal column. As shown in FIGS. 2 to 5, the spine circulator has five S-shaped ball grooves (4 d) whose central trajectories are spatial curves. 4e is a ball flow port for the S-shaped ball groove (4d). The two positioning posts (4c) at both ends of the circulator (4) are used for axial positioning of the nut. As shown in FIGS. 6, 8, and 10, the circulator (4) is the nut (2). The closed part of the circulator ball groove (4d) faces the lead screw unit, and the open part of the ball groove (4d) is the arcuate shape of the nut linear groove. Facing the curved surface (2b), the edge of the ball groove (4d) matches the arcuate curved surface (2b) of the nut, and the ball groove (4d) and the arcuate curved surface (2b) of the nut cooperate. Work to form a return path for the ball (3).

  As shown in FIG. 10, the circulator (4) protrudes into the spiral passage of the lead screw unit at the ball inlet and outlet (4a) of the ball groove. The protruding portion at the ball inlet of the ball groove of the circulator is connected to the protruding portion at the ball outlet to form a spiral protruding beam to form a semicircular cross section. The spiral protruding beam (4b) has a shape that matches the spiral passage (1a) in the lead screw unit. The protruding beam (4b) is loosely connected to a spiral passage in the lead screw unit. The protruding beam (4b) not only positions the circulator in the axial direction but also increases the strength of the circulator.

  As shown in FIGS. 2, 3, 4, 5, and 8, the two positioning posts (4c) at both ends of the circulator (4) are inserted into the passages outside the nut (2). The outer passage is the unused portion of the nut passage except for the ball loop. The two positioning posts (4c) are loosely connected to the inserted nut passage. The positioning post (4c) is mainly used to allow the circulator (4) and the nut passage to be kept in a relatively stationary position during assembly.

  The protruding beam (4b) is loosely connected to the spiral passage in the lead screw unit. The two positioning posts (4c) are loosely connected to the nut passage. The circulator (4) is attached in a floating state in the axial direction of the nut (2), and is aligned during the operation in order to improve the operational smoothness of the lead screw unit during the reverse operation of the ball. In the radial direction of the nut, the arcuate curved surface of the straight groove of the nut, which is part of the ball return passage, transitions toward the bottom of the nut passage at the part where it is cut off, thereby making it easy and smooth Therefore, there is no disadvantage that the transition of the connection between the circulator and the nut passage is difficult, and the stability of the reverse operation of the ball is lowered without forming a step portion. In the present invention, the internal passage structure is applied so that the ball does not cross the tooth tip of the lead screw unit during the reverse operation, and the chamfer angle of the tooth tip of the lead screw unit with respect to the reverse operation of the ball is determined. The effect is eliminated and the smooth operation of the lead screw unit is improved.

  An important feature of this example is that the length of the ball return passage is lengthened to avoid collision with the lead screw unit passage during the reverse movement of the ball and to increase the smoothness of operation of the lead screw unit with the same circulator width. Therefore, the circulator (4) protrudes into the spiral passage of the lead screw unit at the ball inlet and outlet (4a) (ball flow port) of the ball groove. In order to reduce manufacturing costs and increase manufacturing efficiency, the circulator is formed from nylon 6 by injection molding. Further, the raw material of the circulator may be another engineering plastic such as PC or PA.

  In this example, it is preferable that the linear groove (2a) in the longitudinal direction of the nut has a central angle of 90 °. Increasing the central angle enhances the smooth reverse movement of the ball and the smooth movement of the lead screw unit, but reduces the support capability of the spinal internal circulation ball screw unit. The central angle is preferably 75 ° to 95 ° depending on the diameter ratio of the ball to the lead screw unit.

It is an exploded view of the accessory of the spine type internal circulation ball screw unit of the present invention. It is a front view of the circulator of the spine type internal circulation ball screw unit of the present invention. It is a figure of the left side of the circulator of the spine type internal circulation ball screw unit of this invention. It is a top view of the circulator of the spine type internal circulation ball screw unit of the present invention. It is an upper view of the circulator of the spine type internal circulation ball screw unit of the present invention. It is sectional drawing of the circulator of the spine type internal circulation ball screw unit of this invention. It is sectional drawing of the circulator of the spine type internal circulation ball screw unit of this invention. It is sectional drawing of the assembled nut and circulator of the spine type | mold internal circulation ball screw unit of this invention. It is a figure of the cross section A in FIG. FIG. 3 is a cross-sectional view of an assumed three-dimensional surface of the center of all balls along the loop of the spinal column internal circulation ball screw of the present invention.

Claims (7)

A spinal column type internal circulation ball screw unit comprising a lead screw unit, a nut, a plurality of balls, and a ball circulator having an S-shaped ball groove, wherein a longitudinal linear groove is provided on the inner surface of the nut In the ball screw unit, the linear groove cuts out a spiral passage of the nut, and the circulator is attached to the inside of the linear groove of the nut.
The circulator having a ball groove, wherein the bottom of the straight groove is an arch-shaped curved surface, and the bottom of the passage of the nut smoothly transitions toward the arch-shaped curved surface at a portion where the nut is cut. The inner side of the ball groove is directed to the lead screw unit, while the open side of the ball groove is directed to the arched curved surface of the linear groove, and the ball return path cooperates with the arched curved surface. Characterized by forming,
Combining the advantages of external circulation with the advantages of internal circulation, it not only has the same compact structure and small nut radius size as the internal circulation type, but also has the A spine-type internal circulation ball screw unit characterized by being a kind of internal circulation ball screw unit that overcomes the disadvantages of the present invention and has simple manufacturing technology and good operating smoothness.   2. The spinal column type internal circulation ball screw unit according to claim 1, wherein the circulator projects into a spiral passage of the lead screw unit at a ball inlet and an outlet of the ball groove.   The spinal column type internal circulation ball screw unit according to claim 2, wherein the protruding portion at the ball inlet of the ball groove of the circulator is connected to the protruding portion at the ball outlet to form a spiral protruding beam. .   The spinal column type internal circulation ball screw unit according to claim 1, wherein projecting positioning posts are disposed at both ends of the circulator and inserted into a passage of a nut outside the ball loop.   The spinal column type internal circulation ball screw unit according to any one of claims 1 to 4, wherein the arcuate curved surface is in tangential contact with the bottom of the nut passage.   The spinal column type internal circulation ball screw unit according to any one of claims 1 to 4, wherein the circulator is formed of an engineering plastic.   The spinal column type internal circulation ball screw unit according to any one of claims 1 to 4, wherein the longitudinal linear groove has a central angle of 75 ° to 95 °.

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