KR20210115088A - Ball screw capable of measuring and adjusting preload in real time - Google Patents

Abstract

A ball screw for measuring and adjusting preload in real time comprises: a first nut and a second nut which are coupled with a screw; a preload unit including a first preload piece and a second preload piece which are arranged between the first nut and the second nut and contact with each other by an inclined surface; a preload measuring member placed on the first or the second preload piece to measure preload between the first and the second nut; and a preload adjusting member which is placed on the first preload piece, is extended along the radial direction of the screw, and adjusts a distance in an axial direction between the first preload piece and the second preload piece by pushing the first preload piece to move along the radial direction. The ball screw measures preload in real time to maintain machining accuracy and to extend useful life of the ball screw.

Description

BALL SCREW CAPABLE OF MEASURING AND ADJUSTING PRELOAD IN REAL TIME

The present invention relates to a ball screw, and more particularly, to a ball screw capable of measuring and adjusting a preload in real time.

Because ball screws have the advantages of precise transmission and reliable transmission, generally preload is applied to the nut in advance to continuously push the nut in a single direction so that the screw thread, nut thread and rolling element are used to eliminate backlash in the ball screw. may be in contact with each other. However, this kind of structure can only provide a preload for fixing the nut, and cannot measure and adjust the preload in real time.

1A, which is one of the drawings of Taiwan Patent No. 085215581, it shows a piezoelectric preload adjustment and positioning fine adjustment mechanism of a ball screw, wherein a spacer ring 113 is interposed between the double nuts 111 and 112. and a preload spring seat 114 and a preload spring 115 are provided between the spacer ring 113 and the nuts 111 and 112 . A piezoelectric actuator seat 116 is provided between the spacer rings 113 , and the piezoelectric actuator seat 116 is provided with a piezoelectric actuator 117 and a dynamometer 118 , and two of a piezoelectric actuator 117 and a dynamometer 118 . The ends of the dogs each abut against the spacer ring 113 . By changing the length of the piezoelectric actuator 117, the displacement of the spacer ring 113 is changed to achieve preload control of the ball screw. However, it still has the following defects in practical use.

First, the piezoelectric actuator 117 is disposed in the spacer ring 113 along the axial direction, so that the piezoelectric actuator 117 extends and contracts along the axial direction, thereby providing for the preload applied to the nuts 111 and 112. Provides axial force variation. However, since a preload is previously applied to the nuts 111 and 112 in the axial direction, if the preload of the nuts 111 and 112 is changed, the thrust value directly required by the piezoelectric actuator 117 must be large, and the piezoelectric actuator (117) The cost of producing a large thrust value is relatively high.

Second, since the piezoelectric actuator 117 is disposed in the spacer ring 113 along the axial direction and is assembled only on one side of the screw 119, when the piezoelectric actuator 117 is extended, pushing only to one side is large and It causes a parallelism problem between the small nuts (111, 112).

1B, which is one of the drawings in Taiwan Patent No. 094126109, there is shown an adjustable preload structure of a ball screw. The preload structure essentially comprises two preload pieces 131 , 132 . An inclined surface 131A, 132A is formed on one end surface of each preload piece 131 , 132 , each preload piece 131 , 132 being sleeved between two nuts 133 , 134 of a ball screw. and in this way the inclined surfaces 131A, 132A of the preload pieces 131 , 132 are in contact with each other. Due to the relative displacement between the preload pieces 131 , 132 , a force is applied between the two nuts 133 , 134 . Due to the variation in the combined thickness of the preload pieces 131 , 132 different preloads are generated. However, it still has the following defects in practical use.

Since such an adjustable preload structure can only manually adjust the preload pieces 131 and 132 to generate different preloads, disassembly must be performed during adjustment, emphasizing the disadvantage that the preload cannot be adjusted in real time and the adjustment is inconvenient. do. In addition, such an adjustable preload structure cannot immediately measure whether the preload of the ball screw has failed, and cannot maintain processing accuracy and service life of the ball screw.

The present invention seeks to obviate and/or alleviate the above-mentioned disadvantages.

One object of the present invention is to provide a ball screw capable of measuring and adjusting the preload in real time, which mainly maintains machining accuracy and prolongs the service life of the ball lead screw.

Another object of the present invention is to provide a ball screw capable of measuring and adjusting the preload in real time, which mainly reduces the cost required to adjust the preload and avoids the parallelism problem between the large nut and the small nut.

In order to achieve the above object, the ball screw capable of measuring and adjusting the preload in real time provided by the present invention is:

a screw shaft extending along the axial direction;

a first nut screwed to said screw shaft (20) via a plurality of first rolling elements and comprising a first assembly surface;

a second nut screwed to said screw shaft via a plurality of second rolling elements and comprising a second assembly surface facing said first assembly surface;

A preload unit disposed between the first nut and the second nut and including a first preload piece and a second preload piece, wherein the first preload piece comprises a first insertion hole for insertion of the screw shaft, the first a first pressure surface abutting a first assembly surface, and a first inclined surface forming a first angle with respect to the first pressure surface, wherein the second preload piece comprises a second insertion hole for insertion of the screw shaft; a preload unit comprising a second pressing surface abutting the second assembly surface, and a second inclined surface forming a second angle with respect to the second pressing surface and abutting the first inclined surface;

a preload measuring member disposed in the first or second preload piece to measure a preload value between the first nut and the second nut; and

a preload adjusting member disposed in the first preload piece and extending along a radial direction of the screw shaft, by pushing the first preloading piece to move it in the radial direction so that the first pressure surface and the second pressure surface along the axial direction are moved. and a preload adjustment member for varying the distance between the pressing surfaces.

According to the present invention, the preload measuring member measures the preload value between the first nut and the second nut, and when the measured preload value is different from the set preload value, the preload adjusting member moves the first and second preload pieces in the axial direction. Controlled to change the thickness, characterized in that the force between the two nuts is changed due to the change in the thickness of the two preload pieces. The preload is measured and adjusted in real time, which can achieve the purpose of reducing the cost of adjusting the preload and avoiding the problem of parallelism between the two nuts, while maintaining the machining accuracy and extending the service life of the ball screw.

These, together with other objects of the invention, together with the various novel features which characterize it, will be particularly pointed out in the claims which follow and form a part of this specification. For a better understanding of the present invention, its operational advantages and the specific objects obtained by its use, reference should be made to the accompanying drawings and the detailed description set forth with respect to preferred embodiments of the present invention.

According to the present invention, it is possible to provide a ball screw capable of measuring and adjusting the preload in real time, which can mainly maintain processing accuracy and extend the service life of the ball lead screw. Further, according to the present invention, it is possible to provide a ball screw capable of measuring and adjusting the preload in real time, which mainly reduces the cost required for adjusting the preload and avoids the problem of parallelism between the large nut and the small nut.

1A is one of the drawings in Taiwan Patent No. 085215581;
1B is one of the drawings in Taiwan Patent No. 094126109;
Figure 2 is a perspective assembly view of an embodiment of the present invention.
3 is a partially exploded perspective view of an embodiment of the present invention;
Fig. 4A is an exploded perspective view of an embodiment of the present invention, showing a state in which a preload unit and a preload adjusting member are separated;
Fig. 4B is an exploded perspective view of the embodiment of the present invention, showing a state in which the preload unit and the preload adjusting member are separated from each other;
Fig. 5 is a cross-sectional view taken along line 5-5 of Fig. 2;
Fig. 6 is a cross-sectional view taken along line 6-6 of Fig. 2;
7A is a schematic diagram of the operation of an embodiment of the present invention;
7B is an operation schematic diagram of an embodiment of the present invention;
8 is an operational flow diagram of an embodiment of the present invention;
Fig. 9 is a cross-sectional view of another embodiment of the present invention, showing a state in which a preload measuring member is provided on the first preload piece;

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings, which show, for illustrative purposes only, a preferred embodiment according to the invention.

2 to 7A, a ball screw capable of measuring and adjusting a preload in real time according to an embodiment of the present invention is essentially a screw shaft 20, a first nut 30, a second nut 40, It includes a preload unit 50 , a preload measuring member 60 , and a preload adjusting member 70 .

The screw shaft 20 extends along the axial direction (X).

The first nut 30 is screwed to the screw shaft 20 via a plurality of first rolling elements 91 , a first end surface 31 , a first assembly surface opposite the first end surface 31 . 32 , and a first keyway 33 recessed from the outer surface of the first nut 30 and adjacent the first assembly surface 32 . In this embodiment, the first rolling element 91 is a ball, and may also be a roller or a needle.

The second nut 40 is screwed to the screw shaft 20 via a plurality of second rolling elements 92 , the second assembly surface 41 facing the first assembly surface 32 , the axial direction X ) along the second end surface 42 opposite the second assembly surface 41 , and a second keyway recessed from the outer surface of the second nut 40 and adjacent the second assembly surface 41 ( 43). In this embodiment, the second rolling element 92 is a ball, and of course can also be a roller or a needle corresponding to the first rolling element 91 .

The preload unit 50 is disposed between the first nut 30 and the second nut 40 , and includes a first preload piece 51 and a second preload piece 52 .

The first preload piece 51 includes a first insertion hole 511 for insertion of the screw shaft 20 , a first pressing surface 512 abutting the first assembly surface 32 , and a first pressing surface 512 . and a first inclined surface 514 defining a first angle 513 with respect to . In this embodiment, the first angle 513 is 17 degrees, but is not limited thereto. The first angle 513 may be designed to be 5 degrees to 45 degrees, which can reduce the thrust value and stress loss required by the preload adjustment member 70 , and the use can be reduced. Further, the first preload piece 51 further has a receiving groove 515 recessed along the radial direction Y of the screw shaft 20 , the receiving groove 515 having a groove lower surface 515A and a groove lower portion It is formed by a groove wall surface 515B connecting the perimeter of surface 515A. The connection between the first pressing surface 512 and the first inclined surface 514 is formed as a connection line 516 parallel to the groove lower surface 515A.

The second preload piece 52 includes a second insertion hole 521 for insertion of the screw shaft 20 , a second pressing surface 522 abutting the second assembly surface 41 , and a second pressing surface 522 . a second inclined surface 524 forming a second angle 523 with respect to and abutting the first inclined surface 514 . In this embodiment, the second angle is 17 degrees, but this is not limited now. The design and effect of the second angle is the same as that of the first preload piece 51 . Further, the second preload piece 52 is further provided with an assembly groove 525 recessed in the axial direction (X) from the second pressing surface 522 , and the pressing plate 94 is provided in the assembly groove 525 . and in this way the outer surface 941 of the pressure plate 94 is level with the second pressure surface 522 and abuts the second assembly surface 41 of the second nut 40 . Finally, the two insertion pins 95 are inserted through the second preload piece 52 and the second nut 40 so that the second preload piece 52 and the second nut 40 are connected to the screw shaft 20 ) are positioned in the axial direction X without being separated from each other, avoiding displacement of the second preload piece 52 along the radial direction Y of the

The preload measuring member 60 is disposed in the assembly groove 525 of the second preload piece 52 to measure the preload value between the first nut 30 and the second nut 40 . In this embodiment, the preload measuring member 60 is a film-type force sensor and has a sensing area 61 that is pressed against the inner surface 942 of the pressure plate 94 so that the first nut 30 and A preload value between the second nuts 40 may be measured through the pressure plate 94 . Further, in the preload measuring member 60, used for signal and power transmission, extending along two sides of the second preload piece 52 and passing through the first preload piece 51 along the axial direction X Two wires 62 are further provided, reaching the first nut 30 for electrical connection.

The preload adjusting member 70 is disposed in the receiving groove 515 of the first preload piece 51 and may extend along the radial direction Y of the screw shaft 20 , so as to push the first preload piece 51 . Moving in the radial direction (Y) changes the distance between the first pressing surface (512) and the second pressing surface (522) along the axial direction (X). In this embodiment, the preload adjusting member 70 is a piezoelectric actuator and is fixed in the receiving groove 515 by the fixing key 80 . The fixed key 80 is positioned on the two sides of the limiting portion 81 and the limiting portion 81 corresponding to the receiving groove 515, respectively, and the first keyway 33 of the first nut 30 and the second 2 It comprises two fastening portions 82 , 83 to be placed in the second keyway 43 of the nut 40 . The fixing part 82 disposed in the first keyway 33 is fixed to the first nut 30 by a screw 96 , and the fixing part 83 disposed in the second keyway 43 is not fixed. does not Of course, it can also fix the fixing part 83 disposed in the second keyway 43 instead of fixing the first fixing part 82 disposed in the first keyway 33 , that is, the fixing part Only one of (82, 83) needs to be fixed. Further, the preload adjustment member 70 has a first abutment surface 71 abutting the limiting portion 81 and a second abutment surface 72 opposing the first abutment surface 71 in the radial direction Y This is additionally provided. The second abutment surface 72 abuts against the groove lower surface 515A of the receiving groove 515 of the first preload piece 51 and first abuts along the radial direction Y of the screw shaft 20 . It can be moved towards or from the surface 71 . In this embodiment, the preload adjusting member with the amount of displacement of the first preloading piece 51 driven by the preload adjusting member 70 along the radial direction Y of the screw shaft 20 affected by the assembly and manufacturing tolerances A washer 97 is provided between the second abutment surface 72 of 70 and the groove lower surface 515A of the receiving groove 515 . Finally, the preload adjustment member 70 is provided with two connecting pins 73 which serve as signal and power transmission and extend from the retaining key 80 through the receiving groove 515 for electrical connection.

The above is a description of the configuration of the main components of the embodiment of the present invention. The operation mode and effect of the present invention will be described as follows.

7A, 7B and 8 , the preload measuring member 60 measures a preload value between the first nut 30 and the second nut 40 , and the measured preload value is a predetermined preload value and In the same case, the preload measuring member 60 continues to measure the preload value.

Once the measured preload value is less than the predetermined preload value, the preload adjusting member 70 is controlled to extend along the radial direction Y. Since the first abutment surface 71 of the preload adjustment member 70 is stopped by the fixed key 80 , the second abutment surface 72 of the preload adjustment member 70 only moves in the radial direction Y. It can be moved upward and further drives the first preload piece 51 to move upward simultaneously in the radial direction Y. The first preload piece 51 moved upward in the radial direction Y abuts against the second inclined surface 524 of the second preload piece 52 by its first inclined surface 514, the second preload piece 52 is fixed to the second nut 40 along the axial direction X by an insertion pin 95 so that the second preload piece 52 is moved only in the axial direction X, thereby With (X) it is possible to change the combined thickness of the first preload piece 51 and the second preload piece 52 , ie the first pressure surface 512 of the first preload piece 51 in the axial direction X ) and the second pressing surface 522 of the second preloading piece 52 are changed, the force between the nuts is increased due to the increased thickness of the two preloading pieces, whereby the first nut 30 and Increase the value of the preload between the second nuts (40).

While increasing the preload value between the first nut 30 and the second nut 40 , the preload adjusting member 60 continues to measure the preload value between the first nut 30 and the second nut 40 . When the measured preload value is equal to the predetermined preload value, the preload adjusting member 70 stops the action of adjusting the preload.

Therefore, since the present invention can measure and adjust the preload in real time, it can maintain the operation accuracy and extend the service life of the ball screw. Further, the first pressing surface 512 of the first preload piece 51 is abutted against each other by an inclined surface, and the first pressing surface 512 of the first preload piece 51 is the first pressing surface 512 of the first nut 30 . 1 fully abutting the assembly surface 32, the second pressing surface 522 of the second preload piece 52 fully abutting the second assembly surface 41 of the second nut 40, the first nut ( 30) and the second nut 40 are stressed relatively uniformly during displacement in the axial direction (X), which can reduce the cost required to adjust the preload and avoid the problem of parallelism between the two nuts .

It is worth mentioning that since the preload adjusting member 70 is a piezoelectric actuator, the cost of the piezoelectric actuator will increase with the increase in thrust. In the present invention, a piezoelectric actuator is used in combination with the preload unit 50, and the first preload piece 51 and the second preload piece 52 of the preload unit 50 abut against each other by an inclined surface, and the second The angle between the first preload piece 51 and the second preload piece 52 is limited to be 5 degrees to 45 degrees. Therefore, the preload unit 50 is of a labor-reducing structural design, so to push the first preload piece 51 to move it in the radial direction Y and push the second preload piece 52 to move it in the radial direction Y The thrust required by the piezoelectric actuator can be reduced, which can effectively reduce the cost.

Referring to Fig. 9, another preferred embodiment of the present invention is shown, which differs from the above embodiment in the following respects.

The preload measuring member 60 is disposed within the first preload piece 51 and is configured to measure a preload value between the first nut 30 and the second nut 40 on the first assembly surface 32 of the first nut 30 . ) in close contact with In this embodiment, since both the preload measuring member 60 and the preload adjusting member 70 are disposed in the first preload piece 51, after the preload measuring member 60 is assembled, the preload adjusting member 70 are immediately assembled on the same preload piece, thereby saving assembly time.

While various embodiments in accordance with the present invention have been shown and described, it will be apparent to those skilled in the art that there may be additional embodiments within the scope of the present invention.

Claims (3)

A ball screw capable of measuring and adjusting the preload in real time;
a screw shaft 20 extending along the axial direction (X);
a first nut (30) screwed to said screw shaft (20) via a plurality of first rolling elements (91) and comprising a first assembly surface (32);
a second nut (40) screwed to said screw shaft (20) via a plurality of second rolling elements (92) and comprising a second assembly surface (41) facing said first assembly surface (32);
A preload unit (50) disposed between the first nut (30) and the second nut (40) and including a first preload piece (51) and a second preload piece (52), wherein the first preload piece 51 is a first insertion hole 511 for insertion of the screw shaft 20 , a first pressing surface 512 abutting the first assembly surface 32 , and the first pressing surface 512 . a first inclined surface (514) defining a first angle (513) with respect to the 2 A second pressing surface 522 abutting the assembly surface 41 , and a second inclined surface forming a second angle 523 with respect to the second pressing surface 522 and abutting the first inclined surface 514 . a preload unit (50), including (524);
a preload measuring member (60) disposed in the first preload piece (51) or the second preload piece (52) to measure a preload value between the first nut (30) and the second nut (40); and
A preload adjusting member 70 disposed in the first preload piece 51 and extending along the radial direction Y of the screw shaft 20 by pushing the first preload piece 51 in the radial direction Y ) to change the distance between the first pressing surface (512) and the second pressing surface (513) along the axial direction (X),
Containing, a ball screw. According to claim 1, further comprising a fixing key (80), the first preload piece (51) is further provided with a receiving groove (515), the fixing key (80) in the receiving groove (515) a corresponding limiting portion (81), and a fixing portion (82, 83) secured to the first nut (30) or the second nut (40), the preload adjustment member (70) comprising the first receiving portion (70) a first abutment surface 71 disposed within the groove 515 and abutting the limiting portion 81 , and a second abutment surface 71 opposite the first abutment surface 71 in the radial direction Y; 72), wherein the second abutment surface (72) abuts a groove lower surface of the receiving groove (515) and along the radial direction (Y) of the screw shaft (20) the first abutment surface A ball screw, moving towards or away from (71). 3. The fixed key (80) according to claim 2, wherein the first nut (30) is provided with a first keyway (33), the second nut (40) is provided with a second keyway (43), and the fixed key (80) is a ball screw having two said fixing parts (82, 83), respectively arranged in said first keyway (33) and said second keyway (43).

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