CN113280091B

CN113280091B - Ball screw capable of real-time measuring and adjusting pre-pressure

Info

Publication number: CN113280091B
Application number: CN202010101285.3A
Authority: CN
Inventors: 林映汝; 魏照恩
Original assignee: Hiwin Technologies Corp
Current assignee: Hiwin Technologies Corp
Priority date: 2020-02-19
Filing date: 2020-02-19
Publication date: 2022-06-10
Anticipated expiration: 2040-02-19
Also published as: CN113280091A

Abstract

The invention discloses a ball screw capable of measuring and adjusting pre-pressure in real time, comprising: the first nut and the second nut are screwed on a screw rod; the pre-pressing unit is arranged between the first screw cap and the second screw cap and comprises a first pre-pressing piece and a second pre-pressing piece; the first preforming piece and the second preforming piece are mutually abutted and contacted by an inclined plane; a preload measuring element, which is arranged on the first preload sheet or the second preload sheet and is used for measuring the preload value between the first nut and the second nut; and the prepressing adjusting element can be arranged on the first prepressing piece in a telescopic manner along the radial direction of the screw rod and is used for pushing the first prepressing piece to move along the radial direction so as to change the distance between the first prepressing piece and the second prepressing piece in the axial direction. So as to measure and adjust the pre-pressure in real time, and achieve the purpose of maintaining the processing precision and prolonging the service life of the ball screw.

Description

Ball screw capable of real-time measuring and adjusting pre-pressure

Technical Field

The present invention relates to a ball screw with double nuts, and more particularly to a ball screw capable of measuring and adjusting pre-pressure in real time.

Background

Because the ball screw has the advantages of precise transmission and reliable transmission, the ball screw is widely applied to precise machinery, and in order to eliminate the problem of the backlash of the ball screw, a pressure is usually preset on a nut in design so as to fix the nut to push against in a single direction, so that screw threads, nut threads and rolling pieces can be mutually abutted, and the problem of the backlash of the ball screw is solved.

Referring to fig. 1A, which shows one of drawings of taiwan patent application No. 085215581, the patent document is a piezoelectric type pre-compression adjustment and positioning fine adjustment mechanism for a ball screw, wherein a spacer ring 113 is disposed between two

nuts

111, 112 of the ball screw, a pre-compression spring seat 114 and a pre-compression spring 115 are disposed between the spacer ring 113 and the

nuts

111, 112, a piezoelectric actuator seat 116 is disposed between the spacer rings 113, a piezoelectric actuator 117 and a dynamometer 118 are disposed in the piezoelectric actuator seat 116, two ends of the piezoelectric actuator 117 and the dynamometer 118 respectively abut against the spacer ring 113, and by changing the length of the piezoelectric actuator 117, the displacement of the spacer ring 113 is changed to achieve pre-compression control of the ball screw; however, the following drawbacks are still present in practical use:

first, the piezoelectric actuator 117 of the prior art is disposed on the spacer ring 113 along the axial direction, so that the piezoelectric actuator 117 extends and contracts along the axial direction, and further provides the pre-pressure for changing the axial force applied to the

nuts

111, 112, however, since the

nuts

111, 112 are pre-stressed in the axial direction, if the pre-pressure of the

nuts

111, 113 is to be changed, the thrust value directly required by the piezoelectric actuator 117 is necessarily large, and the cost of the piezoelectric actuator 117 capable of generating a large thrust value is relatively high.

Secondly, since the piezoelectric actuator 117 of the prior art is disposed along the axial direction of the spacer ring 113, and the piezoelectric actuator 117 is only assembled at a single side of the screw 119, when the piezoelectric actuator 117 extends, the problem of parallelism between the

size nuts

111, 112 is caused by the pushing of the single side.

Referring to fig. 1B, a drawing of taiwan patent application No. 094126109 is shown, which is an adjustable pre-pressing structure for a ball screw, the pre-pressing structure is mainly composed of two

pre-pressing pieces

131, 132, and an

inclined surface

131A, 132A is formed on one end surface of each

pre-pressing piece

131, 132, each

pre-pressing piece

131, 132 is respectively sleeved between two

nuts

133, 134 of the ball screw, and the

inclined surfaces

131A, 132A of each

pre-pressing piece

131, 132 are in corresponding contact with each other, by means of the relative displacement of each

pre-pressing piece

131, 132, the two

nuts

133, 134 are stressed, and pre-pressing forces of different sizes are generated due to the combined thickness change of the

pre-pressing pieces

131, 132; however, the following drawbacks are still present in practical use:

since the prepress of this patent can only adjust the

prepressures

131 and 132 manually to generate different prepressures, the disassembling operation is required during the adjustment, which highlights the defects of incapability of adjusting the prepressures in real time and inconvenience in adjustment. In addition, the prior art cannot detect immediately whether the pre-pressure of the ball screw is lost, and cannot maintain the processing precision and the service life of the ball screw.

Disclosure of Invention

The present invention provides a ball screw capable of measuring and adjusting pre-pressure in real time, which mainly maintains the processing precision and prolongs the service life of the ball screw.

Another objective of the present invention is to provide a ball screw capable of measuring and adjusting the pre-pressure in real time, which mainly reduces the cost required for adjusting the pre-pressure and avoids the problem of parallelism between the large and small nuts.

To achieve the above object, the present invention provides a ball screw capable of measuring and adjusting pre-pressure in real time, comprising: a screw rod extending along an axial direction; the first nut is screwed on the screw rod through a plurality of first rolling pieces and comprises a first group of arrangement surfaces along the axial direction; the second screw cap is screwed on the screw rod through a plurality of second rolling pieces and comprises a second assembling surface facing the first assembling surface; the pre-pressing unit is arranged between the first screw cap and the second screw cap and comprises a first pre-pressing piece and a second pre-pressing piece; the first pre-pressing piece is provided with a first penetrating hole for the screw to penetrate through, a first pressing surface abutting against the first group of arrangement surfaces, and a first inclined surface forming a first included angle with the first pressing surface; the second preforming piece is provided with a second penetrating hole for the screw to penetrate through, a second pressing surface abutting against the second group of arrangement surfaces, and a second inclined surface which forms a second included angle with the second pressing surface and abuts against the first inclined surface; a pre-pressing measuring element, which is arranged on the first pre-pressing piece or the second pre-pressing piece and is used for measuring the pre-pressing value between the first screw cap and the second screw cap; and a pre-pressing adjusting element which can be arranged on the first pre-pressing piece in a radially telescopic manner along the screw rod and is used for pushing the first pre-pressing piece to move in a radial direction so as to change the distance between the first pressing surface and the second pressing surface in the axial direction.

The invention has the following effects: the prepressing measuring element is used for detecting the prepressing value between the first screw cap and the second screw cap, when the detected prepressing value is different from the set prepressing value, the prepressing adjusting element is controlled to act so as to change the thickness of the first prepressing piece and the second prepressing piece in the axial direction, so that the stress between the two screw caps is changed due to the combination thickness change of the two prepressing pieces, the prepressing can be measured and adjusted in real time, the purposes of maintaining the processing precision and prolonging the service life of the ball lead screw are achieved, and meanwhile, the cost for adjusting the prepressing is reduced and the problem of parallelism between the two screw caps is avoided.

Drawings

FIG. 1A is a diagram of Taiwan patent application No. 085215581.

FIG. 1B is a diagram of Taiwan patent application No. 094126109.

Fig. 2 is a perspective assembly view of an embodiment of the present invention.

Fig. 3 is a partial exploded perspective view of an embodiment of the present invention.

Fig. 4A is an exploded perspective view of the embodiment of the present invention, showing the state in which the pre-pressing unit and the pre-pressing adjusting element are separated.

Fig. 4B is an exploded perspective view of the embodiment of the present invention, showing the pre-pressing unit and the pre-pressing adjustment element separated from each other from another perspective.

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.

FIG. 7A is an operation diagram of the embodiment of the present invention.

FIG. 7B is an operation diagram of the embodiment of the present invention.

FIG. 8 is a flow chart illustrating operation of the present invention.

FIG. 9 is a cross-sectional view of another embodiment of the present invention; displaying the state of the pre-pressure measuring element set in the first pre-pressure piece.

Description of the reference numerals

111. 112 screw cap

113 spacer ring

114 pre-pressing spring seat

115 pre-pressing spring

116 piezoelectric actuator socket

117 piezoelectric actuator

118 dynamometer

119 screw

131. 132 pre-pressing sheet

131A, 132A inclined plane

133. 134 nut

20 screw

X axial direction

Y radial direction

30 first nut

31 first end face

32 first group of setting surfaces

33 first key groove

40 second nut

41 second set of set surfaces

42 second end face

43 second keyway

50 pre-pressing unit

51 first pre-pressing sheet

511 first through hole

512 first pressing surface

513 first included angle

514 first inclined plane

515 holding groove

515A groove bottom

515B groove wall

516 connecting line

52 second Presser

521 second through hole

522 second pressing surface

523 second angle

524 second incline plane

525 groups of grooves

60 pre-pressure measuring device

61 sensing region

62 conducting wire

70 preload adjustment element

71 first butting face

72 second butting face

73 feet

80 fixed key

81 position limiting part

82. 83 fixing part

91 first ball

92 second ball

91 pressing plate

941 outer surface of the cylinder

Inner surface 942

95 bolt

96 screw

97 shim.

Detailed Description

Referring to fig. 2 to 7A, an embodiment of the present invention provides a ball screw capable of measuring and adjusting pre-pressure in real time, which mainly comprises a screw 20, a first nut 30, a second nut 40, a pre-pressure unit 50, a pre-pressure measuring element 60, and a pre-pressure adjusting element 70, wherein:

the screw 20 extends in an axial direction X.

The first nut 30 is screwed on the screw 20 through a plurality of first rolling members 91, and includes a first end surface 31, a first set of surfaces 32 opposite to the first end surface 31 along the axial direction X, and a first key groove 33 recessed from an outer surface and adjacent to the first set of surfaces 32; in this embodiment, the first rolling element 91 is a ball, but may be a roller or a needle roller.

The second nut 40 is screwed on the screw 20 through a plurality of second rolling members 92, and includes a second set of surfaces 41 facing the first set of surfaces 32, a second end surface 42 opposite to the second set of surfaces 41 along the axial direction X, and a second key groove 43 recessed from the outer surface and adjacent to the second set of surfaces 41; in this embodiment, the second rolling members 92 are balls, but may be rollers or needles corresponding to the type of the first rolling members 91.

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

The first pre-pressing piece 51 has a first through hole 511 for the screw 20 to pass through, a first pressing surface 512 abutting against the first set of arrangement surfaces 32, and a first inclined surface 514 forming a first included angle 513 with the first pressing surface 512; in this embodiment, the first included angle 513 is 17 degrees, but not limited thereto, and the first included angle 513 may be between 5 degrees and 45 degrees in design, so as to reduce the stress loss and further reduce the thrust value required by the pre-pressure adjusting element 70, thereby reducing the cost; in addition, the first pre-pressing piece 51 further has a containing groove 515 recessed along the radial direction Y of the screw 20, the containing groove 515 is defined by a groove bottom surface 515A and a groove wall surface 515B connecting the periphery of the groove bottom surface 515A, a connecting portion between the first pressing surface 512 and the first inclined surface 514 is a connecting line 516, and the connecting line 516 is parallel to the groove bottom surface 515A.

The second pre-pressing piece 52 has a second through hole 521 for the screw 20 to pass through, a second pressing surface 522 abutting against the second set surface 41, and a second inclined surface 524 forming a second included angle 523 with the second pressing surface 522 and abutting against the first inclined surface 514; in this embodiment, the second included angle 523 is 17 degrees, but not limited thereto, and the design limitation and the effect of the second included angle 523 are the same as those of the first pre-pressing sheet 51; in addition, the second pre-pressing piece 52 further has a set groove 525 concavely formed from the second pressing surface 522 along the axial direction X, and a pressing plate 94 is disposed in the set groove 525, and an outer surface 941 of the pressing plate 94 and the second pressing surface 522 are coplanar and abut against the second set surface 41 of the second nut 40; finally, the second pre-pressing piece 52 and the second nut 40 are positioned in the axial direction X without separating from each other by inserting the two pins 95, and the second pre-pressing piece 52 is prevented from moving along the radial direction Y of the screw 20.

The preload measuring device 60 is disposed in the assembling groove 525 of the second preload plate 52 for measuring the preload value between the first nut 30 and the second nut 40; the preload measurement device 60 is a thin film type force sensor in the present embodiment, and has a sensing region 61 pressed against the inner surface 942 of the pressure plate 94, so as to measure the preload between the first nut 30 and the second nut 40 through the pressure plate 94; in addition, the preload measuring device 60 further has two wires 62, the two wires 62 are used for signal and power transmission, and electrically connected to the first nut 30 through the first pre-pressing piece 51 along the axial direction X from the side of the second pre-pressing piece 52.

The pre-pressing adjusting element 70 is telescopically disposed in the accommodating groove 515 of the first pre-pressing piece 51 along the radial direction Y of the screw 20, so as to push the first pre-pressing piece 51 to move along the radial direction Y, so as to change the distance between the first pressing surface 512 and the second pressing surface 522 in the axial direction X; in this embodiment, the pre-pressure adjusting element 70 is a piezoelectric actuator and is assembled in the accommodating groove 515 by a fixing key 80, the fixing key 80 has a limiting portion 81 corresponding to the accommodating groove 515 and fixing portions 82 and 83 respectively located at two sides of the limiting portion 81, the two fixing portions 82 and 83 are respectively located in the first key slot 33 of the first nut 30 and the second key slot 43 of the second nut 40, and the fixing portion 82 located in the first key slot 33 is fixed to the first nut 30 by a screw 96, while the fixing portion 83 located in the second key slot 43 is not fixed, and certainly, the fixing portion 83 located in the second key slot 43 can be fixed, and the fixing portion 82 located in the first key slot 33 is not fixed, that is, only one of the two fixing portions 82 and 83 needs to be fixed; in addition, the pre-pressure adjusting element 70 has a first abutting surface 71 abutting against the limiting portion 81 and a second abutting surface 72 opposite to the first abutting surface 71 along the radial direction Y, the second abutting surface 72 abuts against the groove bottom surface 515A of the accommodating groove 515 of the first pre-pressure piece 51, and the second abutting surface 72 can move toward or away from the first abutting surface 71 along the radial direction Y of the screw 20, in this embodiment, a gasket 97 is disposed between the second abutting surface 72 of the pre-pressure adjusting element 70 and the groove bottom surface 515A of the accommodating groove 515, so as to overcome the influence of assembly or manufacturing tolerance on the displacement of the pre-pressure adjusting element 70 that the pre-pressure adjusting element 70 can drive the first pre-pressure piece 51 along the radial direction Y of the screw 20; finally, the pre-load adjusting element 70 has two pins 73 for signal and power transmission, and is located outside through the fixed key 80 by the accommodating groove 515 for electrical connection.

The above description is a configuration description of each main component of the embodiment of the present invention, and the operation and effects of the present invention are described as follows:

referring to fig. 7A, 7B and 8, the preload value between the first nut 30 and the second nut 40 is detected by the preload measuring device 60, and when the detected preload value is the same as the set preload value, the preload measuring device 60 continuously keeps the detection of the preload value.

As soon as the detected preload value is lower than the set preload value, the preload adjustment element 70 is controlled to extend in the radial direction Y. Because the first abutting surface 71 of the pre-pressing adjusting element 70 is limited by the fixing key 80, the second abutting surface 72 of the pre-pressing adjusting element 70 can only move upwards along the radial direction Y, and further drives the first pre-pressing piece 51 to move upwards along the radial direction Y, the first pre-pressing piece 51 moving upwards along the radial direction Y can only move along the axial direction X by the first inclined surface 514 and the second inclined surface 524 of the second pre-pressing piece 52 abutting against each other, and the design that the second pre-pressing piece 52 is axially positioned on the second nut 40 by the plug pin 95, so that the second pre-pressing piece 52 can only move along the axial direction X, and further the thickness of the first pre-pressing piece 51 and the second pre-pressing piece 52 in the axial direction X is changed, that is, the distance between the first pressing surface 512 of the first pre-pressing piece 51 and the second pressing surface 522 of the second pre-pressing piece 52 in the axial direction X is changed, and the stress between the two nuts is increased due to the combined thickness of the two pre-pressing pieces, thereby increasing the preload between the first nut 30 and the second nut 40.

While raising the preload value between the first nut 30 and the second nut 40, the preload measuring device 60 continuously detects the preload value between the first nut 30 and the second nut 40, and when the detected preload value is the same as the set preload value, the preload adjusting device 70 stops adjusting the preload.

Therefore, since the pre-pressure can be measured and adjusted in real time, the invention can maintain the processing precision and prolong the service life of the ball lead screw, and meanwhile, the first pre-pressing piece 51 and the second pre-pressing piece 52 are abutted by inclined surfaces, the first pressing surface 512 of the first pre-pressing piece 51 is abutted against the first group of the setting surface 32 of the first nut 30 on the whole, and the second pressing surface 522 of the second pre-pressing piece 52 is abutted against the second group of the setting surface 41 of the second nut 40 on the whole, so that the first nut 30 and the second nut 40 are stressed more evenly when moving along the axial direction X, the cost for adjusting the pre-pressure is reduced, and the problem of generating parallelism between the two nuts is avoided.

It should be noted that, since the pre-pressing adjusting element 70 employs a piezoelectric actuator, the cost of the piezoelectric actuator will increase with the increase of the thrust, but the invention uses the piezoelectric actuator to match the pre-pressing unit 550, and the first pre-pressing piece 51 and the second pre-pressing piece 52 of the pre-pressing unit 50 are in contact with each other by inclined surfaces, and the included angle between the first pre-pressing piece 51 and the second pre-pressing piece 52 is limited to be between 5 degrees and 45 degrees, so the pre-pressing unit 50 is a labor-saving structure design, and the thrust required by the piezoelectric actuator to push the first pre-pressing piece 51 to displace in the radial Y direction and the second pre-pressing piece 52 to displace in the axial X direction is smaller, thereby effectively reducing the cost.

Referring to fig. 9, another preferred embodiment of the present invention is shown, which is different from the previous embodiment in that:

the preload measuring device 60 is disposed in the first preload piece 51 and tightly attached to the first set of surfaces 32 of the first nut 30 for measuring a preload value between the first nut 30 and the second nut 40; in this embodiment, since the pre-pressure measuring device 60 and the pre-pressure adjusting device 70 are both disposed in the first pre-pressing plate 51, the pre-pressure adjusting device 70 can be immediately assembled on the same pre-pressing plate after the pre-pressure measuring device 60 is assembled, thereby saving the assembling time.

Claims

1. A ball screw capable of measuring and adjusting pre-pressure in real time is characterized in that: comprises the following steps:

a screw rod extending along an axial direction;

the first nut is screwed on the screw rod through a plurality of first rolling pieces and comprises a first group of arrangement surfaces along the axial direction;

the second screw cap is screwed on the screw rod through a plurality of second rolling pieces and comprises a second assembling surface facing the first assembling surface;

the pre-pressing unit is arranged between the first screw cap and the second screw cap and comprises a first pre-pressing piece and a second pre-pressing piece; the first pre-pressing piece is provided with a first penetrating hole for the screw to penetrate through, a first pressing surface abutting against the first group of arrangement surfaces, and a first inclined surface forming a first included angle with the first pressing surface; the second preforming piece is provided with a second penetrating hole for the screw to penetrate through, a second pressing surface abutting against the second group of arrangement surfaces, and a second inclined surface which forms a second included angle with the second pressing surface and abuts against the first inclined surface;

a pre-pressing measuring element, which is arranged on the first pre-pressing piece or the second pre-pressing piece and is used for measuring the pre-pressing value between the first screw cap and the second screw cap; and

and the pre-pressing adjusting element can be arranged on the first pre-pressing piece in a radially telescopic manner along the screw rod and is used for pushing the first pre-pressing piece to move along the radial direction so as to change the distance between the first pressing surface and the second pressing surface in the axial direction.

2. The ball screw of claim 1, wherein the pre-pressure is measured and adjusted in real time, and further comprising: the pre-pressing adjusting element is arranged in the accommodating groove and is provided with a first abutting top surface abutting against the limiting part and a second abutting top surface which is opposite to the first abutting top surface along the radial direction and abuts against the bottom surface of the accommodating groove, and the second abutting top surface can move in or move away from the first abutting top surface along the radial direction of the screw rod.

3. The ball screw of claim 2, wherein the pre-pressure is measured and adjusted in real time, and further comprising: the first nut further comprises a first key groove, the second nut further comprises a second key groove, the number of the fixing parts of the fixing key is two, and the two fixing parts are correspondingly arranged on the first key groove and the second key groove respectively.

4. The ball screw according to claim 2, wherein the pre-pressure is measured and adjusted in real time, and further comprising: the containing groove of the first pre-pressing piece is defined by a groove bottom surface and a groove wall surface connected with the periphery of the groove bottom surface, the joint of the first pressing surface and the first inclined surface of the first pre-pressing piece is a connecting line, and the connecting line is parallel to the groove bottom surface.

5. The ball screw of claim 2, wherein the pre-pressure is measured and adjusted in real time, and further comprising: a gasket is arranged between the second abutting top surface of the pre-pressing adjusting element and the bottom surface of the accommodating groove.

6. The ball screw of claim 1, wherein the pre-pressure is measured and adjusted in real time, and further comprising: a first included angle of the first pre-pressing sheet is between 5 and 45 degrees; the second included angle of the second pre-pressing sheet is between 5 and 45 degrees.

7. The ball screw of claim 1, wherein the pre-pressure is measured and adjusted in real time, and further comprising: the second pre-pressing piece and the second nut are inserted and positioned by two bolts, so that the second pre-pressing piece is prevented from moving along the radial direction of the screw.

8. The ball screw of claim 1, wherein the pre-pressure is measured and adjusted in real time, and further comprising: the pre-pressure measuring element is a film type force sensor, and the pre-pressure adjusting element is a piezoelectric actuator.