TW201712253A - Dual-nut ball screw having preload sensing function achieving better preload sensing sensitivity and effect of force sensor - Google Patents

Abstract

A dual-nut ball screw having preload sensing function comprises a screw; two nuts; a connecting key; a plurality of balls; a ring-shaped deformable platform, which has a cross section in about a U-shape, and the cross section has a bottom section and two side sections located at two sides of the bottom section and formed with the bottom section as a whole; and a force sensor, which is in a ring shape and disposed at the bottom section of the ring-shaped deformable platform, and located between the two side sections. In which, the bottom section of the ring-shaped deformable platform is extended outwardly with a flange on the other surface opposite to the surface configured with the force sensor. The ring-shaped deformable platform is located in a gap between the two nuts and pressed by the opposite surfaces of the two nuts. In which, on the cross section, the ends of the two side sections are pressed against the opposite surface of one nut, and the surface of the flange is pressed against the opposite surface of the other nut.

Description

Double nut ball screw with sensing pre-pressure function

The present invention relates to a ball screw, and more particularly to a double nut ball screw having a function of sensing a pre-pressure.

The conventional double-nut ball screw is provided with a pre-pressing piece between the two nuts, and a pair of key grooves are respectively arranged on the surface of the two nuts, and then a connecting key is placed to have the two ends respectively located at the two ends. In the keyway of the two nuts, the two nuts can be pressed against the pre-pressing piece to be tightly combined while being operated on the screw, thereby avoiding the shaft which may be generated when the two nuts are moved. The clearance, as well as the rigidity of the ball screw during operation, the positioning accuracy and the stability of the positioning.

After the ball screw is used for a period of time, due to the wear between the ball and the screw and the nut, an axial gap is formed, so that the pre-pressure between the two nuts is gradually reduced, thereby leading to rigidity, positioning accuracy, and positioning stability. The reduction.

It can be seen from the above that the pre-pressure is one of the important indexes for measuring the rigidity, positioning accuracy and positioning stability of the ball screw.

The Republic of China Public Publication No. 201422946 discloses a ball screw for real-time monitoring of pre-pressure, which mainly provides a force sensor between two nuts, by which the pre-sensor between the two nuts is sensed Pressure to monitor.

In addition, Japanese Patent Laid-Open No. Hei 5-141498 discloses a technique for detecting a pre-pressure by placing a pre-pressure detecting means between two nuts.

However, the aforementioned prior art only discloses a technique of placing a force sensor between two nuts, but does not disclose a technique for how to make the force sensor detect the sensitivity and effect of the pre-pressure.

The main object of the present invention is to provide a double-nut ball screw having a function of sensing a pre-pressure, which allows the force sensor to detect the sensitivity and effect of the pre-pressure better.

According to the present invention, a double nut ball screw having a sensing pre-pressure function includes: a screw having an external thread; and two nuts each having an internal thread; the two screws a cap sleeve is screwed to the screw, and the two nuts are combined with the screw system to form a circulation path; the opposite faces of the two nuts have a gap therebetween, and the surfaces of the two nuts each have a The key grooves are opposite to each other and adjacent to the gap; a connecting key is disposed in the key groove of the two nuts and spans the two nuts, and the connecting key spans the gap; a plurality of balls are disposed in the cycle In the path, when the screw rotates, rolling and moving in the circulation path; an annular deformable platform having a substantially U-shaped cross section, a bottom section on the section, and a bottom section a two-side section formed on both sides and integrally formed with the bottom section; and a force sensor having an annular shape disposed at a bottom section of the annular deformable platform and located between the two side sections; wherein the ring The bottom section of the deformable platform is opposite to the surface on which the force sensor is disposed One side extends outwardly from a boss, the width of the boss is not greater than the width of the bottom portion; the annular deformable platform is located in the gap and is pressed by the opposite surface of the two nuts, wherein The ends of the two side sections are pressed against the opposite faces of the nut, and the surface of the bosses is pressed against the opposite surface of the other nut.

Thereby, the effect of the pre-pressure is amplified by the annular deformable platform, so that the sensitivity and effect of the force sensor detecting the pre-pressure are better.

In order to explain the technical features of the present invention in detail, the following preferred embodiments will be described with reference to the drawings, wherein:

As shown in FIG. 1 to FIG. 7 , a double nut ball screw 10 having a sensing pre-pressure function according to a preferred embodiment of the present invention mainly comprises a screw 11 , a second nut 21 , and a connecting key. 31. A plurality of balls 41, an annular deformable platform 51 and a force sensor 61, wherein:

The screw 11 has an external thread 12.

The two nuts 21 each have an internal thread 22 . The two nuts 21 are screwed to the screw 11 , and the two nuts 21 and the screw 11 are combined to form a circulation path 24 . The two nuts 21 have a gap 26 between the opposite faces 211 of the two nuts 21, and the surfaces of the two nuts 21 each have a keyway 28 opposite to each other and adjacent to the gap 26.

The connecting key 31 is disposed in the key groove 28 of the two nut 21 and spans the two nut 21 , and the connecting key 31 spans the gap 26 . Thereby, the connecting key 31 can lock the two nuts 21 so as not to rotate relative to each other, thereby ensuring that the two nuts 21 are maintained screwed on the screw 11 and maintain a fixed distance.

The balls 41 are disposed in the circulation path 24, and are rotatable and movable in the circulation path 24 when the screw 11 rotates.

The annular deformable platform 51 has a substantially U-shaped cross section and has a bottom section 52 on the cross section and two side sections 54 on both sides of the bottom section 52 and integrally formed with the bottom section 52.

The force sensor 61 is annular and disposed on the bottom section 52 of the annular deformable platform 51 and located between the two side sections 54.

The bottom portion 52 of the annular deformable platform 51 extends outwardly from a other surface of the surface of the force sensor 61, and a boss 521 extends outwardly. The width of the boss 521 is not greater than the bottom portion 52. The width. The annular deformable platform 51 is located in the gap 26 and is pressed by the opposite faces 211 opposite to each other by the two nuts 21, wherein the ends of the two side segments 54 are in contact with one another. The opposite surface 211 of the nut 21 is supported by the surface of the boss 521 against the opposite surface 211 of the other nut 21 .

In this embodiment, the two side sections 54 of the annular deformable platform 51 are perpendicular to the bottom section 52 and are parallel to each other; the width of the boss 521 is not more than one-half of the width of the bottom section 52. And the boss 521 is located at the center of the bottom portion 52, and is separated from both sides of the surface of the bottom portion 52 by a predetermined distance; further, the opposite sides of the two side portions 54 are integrally formed with the bottom portion 52. A connecting portion 56 is formed, and the surface of each of the connecting portions 56 is curved in cross section. Wherein, the two side segments 54 are perpendicular to the bottom portion 52, so that the pressing force of the two nuts 21 when pressing the annular deformable platform 51 can be parallel to the two side segments 54, thereby providing The complete supporting force of the bottom portion 52 and the boss 521, if the arrangement is not vertical, the two side segments 54 are more easily deformed when being pressed by the two nuts 21, and the supporting force is not vertically set. So good. In addition, the width of the boss 521 is not more than one-half of the width of the bottom section 52, and the design of the center of the bottom section 52 is mainly utilized when the pressing force acts on the boss 521, the bottom section 52. The portion located on both sides of the boss 521 produces a large deformation and the boss 521 itself produces a small deformation result. This result can moderately enlarge the degree of deformation of the boss 521 to allow the force sensor 61 to The sensing effect is better. Each of the connecting portions 56 is used to provide an appropriate connection effect to increase the structural strength.

The architecture of the present embodiment has been described above, and the operational state of the first embodiment will be described next.

Referring to FIG. 7 again, when not in operation, the opposing surface 211 of the second nut 21 acts on the force of the annular deformable platform 51, that is, the pre-pressure when not in operation. At this time, since the annular deformable platform 51 is opposed to the opposite surface 211 of the two nuts 21 by the end edges of the bosses 521 and the two side segments 54, the boss 521 is The pre-pressure acts to move slightly toward the two side segments 54 , thereby forcing the bottom portion 52 to be correspondingly deformed at the two sides of the boss 521, so that the boss 521 also has a corresponding deformation. It can be sensed by the force sensor 61.

During the operation, the two nuts 21 are reciprocally displaced on the screw 11 by the rotation of the screw 11. During the displacement, the spatial relationship between the two nuts 21 is affected by external force. The effect is changed, that is, the pre-stress between the two nuts 21 changes during the displacement. Further, the deformation of the boss 521 is correspondingly changed, and the change can be sensed by the force sensor 61. Thereby, the user can judge whether the current pre-pressure is normal by the result sensed by the force sensor 61.

As shown in FIG. 8, after a long period of use and wear, the gap between the two nuts 21 increases, which means that the pre-stress between the two nuts 21 will decrease, and the ring can be lowered. The degree of deformation of the deforming platform 51 is reduced, and the state as shown in Fig. 8 is exhibited.

As can be seen from the above, the present invention converts the effect of the pre-pressure into deformation by the annular deformable platform 51, and the force sensor 61 senses whether the pre-pressure is normal. Therefore, the present invention is different from the prior art in that the prior art directly places the force sensor 61 between the two nuts 21 to directly detect the pre-pressure, but does not disclose how to make the sensitivity or the effect better. The invention adopts the design of the annular deformable platform 51 to generate deformation corresponding to the pre-pressure, and is sensed by the force sensor 61, which can be said to amplify the effect of the pre-pressure, and further, The force sensor 61 can be used to detect the sensitivity and effect of the pre-pressure.

10‧‧‧Double nut ball screw with pre-pressure sensing
11‧‧‧ screw
12‧‧‧ external thread
21‧‧‧ nuts
211‧‧‧ opposite
22‧‧‧ internal thread
24‧‧‧Circular path
26‧‧‧ gap
28‧‧‧ keyway
31‧‧‧Links
41‧‧‧ balls
51‧‧‧Annual deformable platform
52‧‧‧ bottom section
521‧‧‧Boss
54‧‧‧ side section
56‧‧‧Connecting Department
61‧‧‧Power Sensor

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of a combination of a preferred embodiment of the present invention. Figure 2 is an exploded view of a preferred embodiment of the present invention. Figure 3 is a perspective view of a partial member of a preferred embodiment of the present invention showing an annular deformable platform. Fig. 4 is a cross-sectional view taken along line 4 of Fig. 3; Figure 5 is a side elevational view of a preferred embodiment of the present invention. Fig. 6 is a cross-sectional view taken along line -6 of Fig. 5. Fig. 7 is a partially enlarged view of Fig. 6. Figure 8 is a view similar to Figure 7 and is a schematic view of the operation of a preferred embodiment of the present invention.

51‧‧‧Annual deformable platform

52‧‧‧ bottom section

521‧‧‧Boss

54‧‧‧ side section

56‧‧‧Connecting Department

Claims (5)

A double nut ball screw having a function of sensing a pre-pressure, comprising: a screw having an external thread; and a second nut each having an internal thread; the two nut being sleeved to the screw And the two nuts and the screw system cooperate to form a circulation path; the opposite surfaces of the two nuts have a gap therebetween, and the surfaces of the two nuts each have a key groove opposite to each other and adjacent to the gap a connecting key disposed in the key groove of the two nuts and spanning the two nuts, and the connecting key spans the gap; a plurality of balls disposed in the circulation path and rotatable in the screw Rolling and moving in the circulation path; an annular deformable platform having a substantially U-shaped cross section, a bottom section on the cross section, and two sides on the bottom section and integrally formed with the bottom section And a force sensor, in the form of a ring, disposed at a bottom portion of the annular deformable platform and located between the two side segments; wherein the bottom portion of the annular deformable platform is disposed The opposite side of the surface of the force sensor extends outwardly The width of the boss is not greater than the width of the bottom portion; the annular deformable platform is located in the gap and is pressed by the opposite faces of the two nuts, wherein the two sides are attached to the cross section The end of the boss abuts against the opposite side of the nut and the surface of the boss abuts against the opposite side of the other nut. A double-nut ball screw having a sensed pre-pressure function according to the first aspect of the patent application, wherein the two side sections are perpendicular to the bottom section and are parallel to each other. A double nut ball screw having a sensing pre-pressure function according to claim 1 of the patent application, wherein: the width of the boss is not more than one-half of the width of the bottom portion. A double-nut ball screw having a sensing pre-pressure function according to the first aspect of the patent application, wherein: a connecting portion is integrally formed between an opposite surface of the two side segments and the bottom portion, and a surface of the connecting portion is The cross section is curved. A double-nut ball screw having a sense pre-pressure function according to the first aspect of the patent application, wherein: the boss is located at a center of the bottom section and spaced apart from both sides of the surface of the bottom section by a predetermined distance.