CN111173907B - Pretension mechanism suitable for double-nut ball screw pair and double-nut ball screw pair - Google Patents

Abstract

The invention provides a pre-tightening mechanism suitable for a double-nut ball screw pair and the double-nut ball screw pair. The main groove is arranged on a main nut sleeved on the screw rod of the double-nut ball screw pair. The auxiliary groove is arranged on the auxiliary nut. The pre-tightening piece is made of elastic materials and is of an arch structure; the pre-tightening piece is suitable for being embedded in the main groove and the auxiliary groove at the same time, and the bow back of the pre-tightening piece faces away from the main groove and the auxiliary groove. The pretightening hoop is of an annular structure with an opening, the pretightening hoop is suitable for surrounding the periphery of the butt joint part of the main nut and the auxiliary nut and is propped against the pretightening sheet, and a threaded connecting piece consisting of a bolt and an adjusting nut is arranged at the opening part of the pretightening hoop. The invention can pretighten and eliminate the new axial clearance generated after the screw rod, the main nut and the auxiliary nut of the double-nut ball screw pair are worn, and the pretightening force of the main nut and the auxiliary nut for butting is convenient to adjust.

Description

Pretension mechanism suitable for double-nut ball screw pair and double-nut ball screw pair

Technical Field

The invention relates to the technical field of ball screw and nut pair transmission, in particular to a pre-tightening mechanism suitable for a double-nut ball screw pair and the double-nut ball screw pair.

Background

At present, the precise ball screw nut pair transmission requires certain unidirectional feeding precision, and the axial clearance between the nut and the screw rod is strictly controlled, otherwise, when the screw rod reversely rotates, a backlash error is generated. In order to eliminate backlash errors caused by axial clearances between the nuts and the screw, the ball screw nut pair generally adopts double-nut pre-tightening to eliminate clearances. The invention patent with the patent number ZL201610943955.X discloses a double-nut pre-tightening ball screw pair, and the pre-tightening structure is as follows: the device comprises a screw rod, a main nut, an auxiliary nut, a pre-tightening block and a compression bar; the screw rod is sleeved with a main nut and an auxiliary nut, a main groove is formed in the end part of the main nut, which faces the auxiliary nut, an auxiliary groove is formed in the end part of the auxiliary nut, which faces the main nut, and the main groove on the end part of the main nut and the auxiliary groove on the end part of the auxiliary nut are aligned one by one; the bottom surface of the main groove is inclined or the bottom surface of the auxiliary groove is inclined, or the bottom surfaces of the main groove and the auxiliary groove are both inclined; the pre-tightening block is provided with an inclined plane, and is inlaid in the main groove of the main nut and the auxiliary groove of the auxiliary nut and can move in the main groove and the auxiliary groove, the two side surfaces of the main groove and the auxiliary groove are contacted with the corresponding surfaces on the pre-tightening block, and the inclined plane of the pre-tightening block is contacted with the bottom surface of the main groove or the bottom surface of the auxiliary groove; the compressing strip is arranged around the butt joint of the main nut and the auxiliary nut and is pressed or indirectly pressed on the pre-tightening block. The principle of the pre-tightening is as follows: the pre-tightening blocks embedded in the main groove and the auxiliary groove are utilized to limit the relative rotation of the main nut and the auxiliary nut, and simultaneously, the pre-tightening blocks are utilized to centripetal movement in the main groove and the auxiliary groove to realize the separation of the main nut and the auxiliary nut along the axial direction to the two sides, so that the pre-tightening clearance elimination of the double-nut ball screw pair is realized.

The disadvantage of the double-nut pre-tightening ball screw pair disclosed in zl201610943955.X patent is: because of errors in manufacturing and installation, the pretightening force generated by each pretightening block for separating the main nut from the auxiliary nut along the axial direction to two sides is unequal, so that a moment for enabling the axis of the auxiliary nut to generate angular displacement relative to the axis of the main nut is formed, and adverse effects are generated on the transmission of the ball screw nut pair.

Disclosure of Invention

The invention provides a pre-tightening mechanism suitable for a double-nut ball screw pair, which aims to solve the technical problem of pre-tightening elimination of axial clearances existing after the screw, a main nut and an auxiliary nut of the double-nut ball screw pair are worn.

The second purpose of the invention is to provide a double-nut ball screw pair, so as to solve the technical problem of pre-tightening elimination of axial clearances existing after the screw, the main nut and the auxiliary nut of the double-nut ball screw pair are worn.

In order to achieve the first object of the present invention, the present invention adopts the following technical scheme:

A pretensioning mechanism for a double-nut ball screw assembly, comprising:

The main groove is arranged on a main nut sleeved on the screw rod of the double-nut ball screw pair, the main groove is arranged on the outer peripheral surface of the main nut facing the side of the auxiliary nut sleeved on the screw rod of the double-nut ball screw pair, and the main groove is provided with a groove side opening facing the auxiliary nut;

the auxiliary groove is arranged on the auxiliary nut, the auxiliary groove is arranged on the outer peripheral surface of one side of the auxiliary nut facing the main nut, and the auxiliary groove is provided with a groove side opening which faces the main nut; the groove side opening of the auxiliary groove is suitable for being abutted with the groove side opening of the main groove along the axial direction of the screw rod, and the auxiliary groove is suitable for being distributed in a staggered manner with the main groove along the circumferential direction of the screw rod;

The pre-tightening piece is made of elastic materials and is of an arch structure; the pre-tightening piece is suitable for being embedded in the main groove and the auxiliary groove at the same time, and the bow back of the pre-tightening piece is opposite to the main groove and the auxiliary groove; and one end of the pre-tightening piece along the circumferential direction of the screw rod is suitable for being propped against one main groove side wall of the main groove, and the other end of the pre-tightening piece along the circumferential direction of the screw rod is suitable for being propped against one auxiliary groove side wall of the auxiliary groove; the two ends of the pre-tightening piece along the circumferential direction of the screw rod respectively abut against the side wall of the main groove and the side wall of the auxiliary groove to form a relative distribution relationship;

the pre-tightening hoop is of an annular structure with an opening, and is suitable for surrounding the periphery of the joint of the main nut and the auxiliary nut and propping against the pre-tightening piece; and a threaded connecting piece consisting of a bolt and an adjusting nut is arranged at the opening of the pre-tightening hoop.

In the preferred embodiment of the invention, a tiny gap exists between one end part of the pre-tightening piece along the axial direction of the screw rod and the side wall of the main groove away from the side opening of the groove; and

A small gap exists between the other end part of the pre-tightening piece along the axial direction of the screw rod and the side wall of the groove, which is far away from the side opening of the groove, of the auxiliary groove.

In a preferred embodiment of the present invention, a position of one main groove side wall of the main groove along the circumferential direction of the screw is located at the groove side opening of the auxiliary groove, and a position of the other main groove side wall of the main groove along the circumferential direction of the screw is located outside the groove side opening of the auxiliary groove; and

One auxiliary groove side wall of the auxiliary groove is positioned at the groove side opening of the main groove along the circumferential direction of the screw rod, and the other auxiliary groove side wall of the auxiliary groove is positioned outside the groove side opening of the main groove along the circumferential direction of the screw rod.

In a preferred embodiment of the present invention, the primary and secondary grooves have equal or unequal groove lengths in a circumferential direction along the lead screw; and

The primary and secondary grooves may have equal or unequal groove widths in an axial direction along the lead screw.

In a preferred embodiment of the present invention, the main nut is provided with a pair of main grooves, and the auxiliary nut is provided with a pair of auxiliary grooves correspondingly; and

The pretensioning mechanism includes a pair of the pretensioning pieces.

In a preferred embodiment of the invention, a pair of flanges which are suitable for being respectively abutted against two end parts of the pretensioning piece along the axial direction of the screw rod are arranged at the contact part of the pretensioning hoop and the pretensioning piece, so that the cross section of the contact part of the pretensioning hoop and the pretensioning piece is in a '╔ ╗' groove shape.

In a preferred embodiment of the present invention, at least one pair of fins are provided on the pre-tightening piece along the circumferential direction of the screw rod;

Two fins of the pair of fins are positioned on the surface of the pre-tightening piece, which is contacted with the pre-tightening hoop;

The pretension is adapted to pass between two fins of a pair of the fins and to bring the fins into abutment with the pretension.

In a preferred embodiment of the invention, two pairs of fins are arranged on the pre-tightening piece along the circumferential direction of the screw rod, and the two pairs of fins are respectively positioned on two sides of the bow back of the pre-tightening piece along the circumferential direction of the screw rod.

In order to achieve the second object of the present invention, the present invention adopts the following technical scheme:

a double-nut ball screw assembly comprising: the screw rod, the main nut and the auxiliary nut which are sleeved on the screw rod in series, and the pre-tightening mechanism.

In the preferred embodiment of the invention, a conical hole coaxial with the axis of the auxiliary nut is formed on the end face of the auxiliary nut facing one end of the main nut;

a cone frustum coaxial with the axis of the main nut is arranged on the end face of the main nut, which faces one end of the auxiliary nut;

The conical surface of the truncated cone on the main nut has the same cone angle as the cone hole on the auxiliary nut; and

The cone frustum on the main nut is inserted into the cone hole on the auxiliary nut, and the cone surface of the cone frustum is contacted with the cone hole on the auxiliary nut to form fit.

Compared with the prior art, the pre-tightening mechanism suitable for the double-nut ball screw pair and the double-nut ball screw pair have the following advantages: ① After the screw rod, the main nut and the auxiliary nut are worn, the axial gap between the screw rod and the main nut and the auxiliary nut which is newly generated due to the wear can be eliminated through a pre-tightening mechanism; ② The moment for enabling the axis of the auxiliary nut to generate angular displacement relative to the axis of the main nut is not generated; ③ The pretightening force for abutting the main nut and the auxiliary nut is convenient to adjust, and only the threaded connecting piece is needed to be screwed or unscrewed.

Drawings

The contents expressed in the drawings of the present specification and the marks in the drawings are briefly described as follows:

FIG. 1 is a schematic view of the basic structure of a double-nut ball screw assembly according to the present invention;

FIG. 2 is a cross-sectional view of FIG. 1, showing the bow back of the pretensioning tab disposed in the main slot and the secondary slot facing away from the bottom surface of the main slot and the bottom surface of the secondary slot, with the two top edges of the pretensioning tab abutting the side walls of the main slot and the side walls of the secondary slot, respectively, and the side walls of the main slot and the side walls of the secondary slot being opposed by the top edges; the pre-tightening hoop is arranged around the joint of the main nut and the auxiliary nut and is pressed on the bow back of the pre-tightening piece; also shown is a threaded connection consisting of a bolt and an adjusting nut provided at the opening of the pretensioning collar;

FIG. 3 is a schematic view of the structure of the main nut and the sub-nut, showing the structure of the main groove on the main nut and the sub-groove on the sub-nut; the end face of the main nut, which is positioned at one end of the auxiliary nut, is provided with a cone frustum which is coaxial with the main nut, and the cone surface of the cone frustum is coaxial with the main nut;

FIG. 4 shows the structure of the primary nut and the secondary nut from another perspective, showing the structure of the primary groove on the primary nut and the secondary groove on the secondary nut; the conical hole coaxial with the auxiliary nut is formed on the end face of the auxiliary nut, which is positioned at one end of the main nut;

FIGS. 5-1 and 5-2 illustrate the construction of the pretensioning plate (where FIG. 5-2 illustrates α);

FIG. 6 shows a flange provided at the location where the pretensioning tab contacts the pretensioning tab;

FIGS. 7-1 and 7-2 show fins symmetrically disposed on the side of the pretensioning plate having the bow back (where FIG. 7-2 shows β);

FIG. 8 shows the threading of the pretensioning clip between fins symmetrically disposed on either side of the pretensioning sheet;

FIG. 9 is a cross-sectional view B-B of FIG. 8 showing the circumferentially disposed pretensioning strap pressed against the bow back of the pretensioning tab provided with fins.

The marks in the drawings are: the screw rod 1, a main nut 2, a conical surface 2-1, a main groove 2-2, a main groove side wall 2-3, a main groove bottom surface 2-4, an auxiliary nut 3, a conical hole 3-1, an auxiliary groove 3-2, an auxiliary groove side wall 3-3, an auxiliary groove bottom surface 3-4, a pre-tightening piece 4, a bow back 4-1, a top edge 4-2, fins 4-3, a pre-tightening hoop 5, a flange 5-4 and an adjusting nut 6.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. Thus, the following detailed description of the embodiments of the invention, as presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, are intended to fall within the scope of the present invention.

Example 1:

Fig. 1 and 2 show the basic structure of the present invention, and the present embodiment describes a specific structure of a double-nut ball screw pair provided with a pretensioning mechanism applied to the double-nut ball screw pair, specifically, the double-nut ball screw pair provided with a pretensioning mechanism applied to the double-nut ball screw pair of the present embodiment includes a screw 1, a main nut 2, an auxiliary nut 3, a pretensioning piece 4, and a pretensioning band 5. The screw rod 1 is sleeved with a main nut 2 and an auxiliary nut 3 in series, the end face of the main nut 2 on one side of the auxiliary nut 3 is tightly contacted with the end face of the auxiliary nut 3 on one side of the main nut 2, and the main nut 2 and the auxiliary nut 3 can rotate relatively.

Referring to fig. 3 and 4, a main groove 2-2 is formed in the outer peripheral surface of the main nut 2 on the side facing the sub nut 3, and the main groove 2-2 extends to the end surface of the main nut 2 on the side facing the sub nut 3, that is, the main groove 2-2 is provided with a groove side opening facing the sub nut 3 (the groove side opening herein refers specifically to the opening of the main groove 2-2 along the axial direction of the main nut 2. Hereinafter, the same applies). The main groove 2-2 has a main groove side wall 2-3 parallel to the axis of the main nut 2 (the main nut 2 axis as referred to herein refers to the axis of the hole in the main nut 2 through which the lead screw 1 passes; the same applies below); an auxiliary groove 3-2 is formed in the outer peripheral surface of the auxiliary nut 3 on the side facing the main nut 2, and the auxiliary groove 3-2 extends up to the end surface of the auxiliary nut 3 on the side facing the main nut 2, that is, the auxiliary groove 3-2 is provided with a groove side opening facing the main nut 2 (the groove side opening herein refers specifically to the opening of the auxiliary groove 3-2 along the axial direction of the auxiliary nut 3). The same applies below). The sub-groove 3-2 has a sub-groove side wall 3-3 parallel to the axis of the sub-nut 3 (the sub-nut 3 axis here means the axis of the hole in the sub-nut 3 through which the screw 1 passes, the same applies hereinafter). Referring to fig. 1, the slot side opening of the sub slot 3-2 is adapted to abut against the slot side opening of the main slot 2-2 along the axial direction of the screw 1, and the main slot 2-2 and the sub slot 3-2 are formed to penetrate through the main slot 2-2 and the sub slot 3-2 by abutting against the slot side opening. However, referring to FIG. 1, the main groove side wall 2-3 of the main groove 2-2 and the sub groove side wall 3-3 of the sub groove 3-2 are offset rather than aligned (i.e., the main groove 2-2 and the sub groove 3-2 are offset in the circumferential direction of the screw 1); In other words, the position of one main groove side wall 2-3 of the main groove 2-2 in the circumferential direction of the screw 1 is at the groove side opening of the sub groove 3-2 (that is, the projection of one main groove side wall 2-3 of the main groove 2-2 in the axial direction of the screw 1 toward the end face of the sub nut 3 contacting the main nut 2, which is located in the groove side opening of the sub groove 3-2), while the position of the other main groove side wall 2-3 of the main groove 2-2 in the circumferential direction of the screw 1 is outside the groove side opening of the sub groove 3-2 (that is, the projection of the other main groove side wall 2-3 of the main groove 2-2 in the axial direction of the screw 1 toward the end face of the sub nut 3 contacting the main nut 2, which is located outside the groove side opening of the sub groove 3-2), One of the sub-groove side walls 3-3 of the sub-groove 3-2 is located at the groove side opening of the main groove 2-2 in the circumferential direction of the screw 1 (that is, the projection of one of the sub-groove side walls 3-3 of the sub-groove 3-2 toward the end face of the main nut 2 contacting the sub-nut 3 in the axial direction of the screw 1, located in the groove side opening of the main groove 2-2), and the other sub-groove side wall 3-3 of the sub-groove 3-2 is located outside the groove side opening of the main groove 2-2 in the circumferential direction of the screw 1 (that is, the projection of the other sub-groove side wall 3-3 of the sub-groove 3-2 toward the end face of the main nut 2 in the axial direction of the screw 1, located outside the groove side opening of the main groove 2-2). for the present embodiment, referring to fig. 1, both main groove side walls 2-3 of the main groove 2-2 of the present embodiment are parallel to the axis of the main nut 2, and both sub groove side walls 3-3 of the sub groove 3-2 of the present embodiment are parallel to the axis of the sub nut 3, that is, the main groove side walls 2-3 of the main groove 2-2 are in parallel relation to the sub groove side walls 3-3 of the sub groove 3-2.

Referring to fig. 2, 5-1 and 5-2, the pre-tension sheet 4 is made of a material having elasticity (e.g., spring steel), and the pre-tension sheet 4 has an arcuate structure. Specifically, the pretensioning piece 4 is curved in an arcuate shape with a bow back 4-1 in the middle along its length direction (i.e., the circumferential direction of the screw shaft 1), and both ends of the pretensioning piece 4 away from the bow back 4-1 (i.e., both ends of the pretensioning piece 4 along the circumferential direction of the screw shaft 1) are a pair of top edges 4-2. Referring to fig. 1 and 2, the same pre-tightening piece 4 is embedded in the main groove 2-2 and the sub-groove 3-2 together, and the bow back 4-1 of the pre-tightening piece 4 faces away from the main groove 2-2 and the sub-groove 3-2 (in other words, the bow opening of the pre-tightening piece 4 faces the main groove 2-2 and the sub-groove 3-2), that is, the bow back 4-1 of the pre-tightening piece 4 faces away from the main groove bottom surface 2-4 of the main groove 2-2 and the sub-groove bottom surface 3-4 of the sub-groove 3-2.

In addition, referring to fig. 1, two top edges 4-2 of the pre-tightening sheet 4 respectively support the main groove side wall 2-3 of the main groove 2-2 and the sub groove side wall 3-3 of the sub groove 3-2, and the main groove side wall 2-3 and the sub groove side wall 3-3 supported by the top edges 4-2 are distributed relatively (in other words, one top edge 4-2 of the pre-tightening sheet 4 supports the main groove side wall 2-3 of the main groove 2-2, the other top edge 4-2 supports the sub groove side wall 3-3 of the sub groove 3-2, and the main groove side wall 2-3 supported by the top edges 4-2 is distributed relatively to the sub groove side wall 3-3). And, from the pretensioning piece 4 along the axial direction of the screw 1, a minute gap exists between one end of the pretensioning piece 4 along the axial direction of the screw 1 and the groove side wall of the main groove 2-2 which is far away from the groove side opening thereof, the minute gap is selected to be 0.1-0.5 mm, and a minute gap exists between the other end of the pretensioning piece 4 along the axial direction of the screw 1 and the groove side wall of the sub groove 3-2 which is far away from the groove side opening thereof, the minute gap is selected to be 0.1-0.5 mm. The significance of this design is that when the pretensioning strap 5 applies pressure to the pretensioning piece 4 to extend and deform the pretensioning piece 4, the existence of the small gap can reduce the friction force between the pretensioning piece 4 and the groove side walls of the main groove 2-2 and the auxiliary groove 3-2 during deformation, that is, reduce the resistance of the pretensioning piece 4 to deformation; on the other hand, the pressure applied by the pretensioning tab 5 to the pretensioning tab 4 can maximally deform the pretensioning tab 4 along the circumferential direction of the screw 1 due to the smaller gap, while reducing the deformation of the pretensioning tab 4 along the axial direction of the screw 1, because the purpose of eliminating the gap between the main nut 2 and the sub-nut 3 is achieved by the deformation of the pretensioning tab 4 along the circumferential direction of the screw 1.

Referring to fig. 1 and 2, the pretensioning collar 5 is made of elastic material (e.g. spring steel), the pretensioning collar 5 is in an open ring shape, the pretensioning collar 5 is circumferentially arranged around the butt joint of the main nut 2 and the sub nut 3 and is pressed against the bow back 4-1 of the pretensioning plate 4, and a threaded connection member composed of a bolt and an adjusting nut 6 is arranged at the opening of the pretensioning collar 5.

Preferably, referring to fig. 3 and 4, the main nut 2 is provided with two main grooves 2-2 symmetrical with respect to the axis of the main nut 2, and the sub nut 3 is provided with two sub grooves 3-2 symmetrical with respect to the axis of the sub nut 3. Obviously, the number of the main grooves 2-2 formed in the main nut 2 can be three or more, and the number of the auxiliary grooves 3-2 formed in the auxiliary nut 3 can be three or more; in addition, the number of the main grooves 2-2 is equal to the number of the sub grooves 3-2 and equal to the number of the pre-tightening tabs 4.

It should be noted that referring to fig. 1 and 2, the primary grooves 2-2 and the secondary grooves 3-2 have equal or unequal groove lengths in the circumferential direction of the screw shaft 1; and the groove widths of the main groove 2-2 and the sub groove 3-2 in the axial direction along the screw shaft 1 are equal or unequal. That is, the specific dimensions of the main groove 2-2 and the sub groove 3-2 in this embodiment can satisfy the use requirement of this embodiment as long as they can form a fit relationship with the pre-tightening piece 4.

The specific working principle of the pre-tightening mechanism suitable for the double-nut ball screw pair is as follows:

referring to fig. 1 and 2, the screw connection piece at the opening of the pretensioning collar 5 is screwed, the opening of the pretensioning collar 5 is reduced, the inner diameter of the annular pretensioning collar 5 is reduced, the centripetal pressure of the pretensioning collar 5 pressed on the bow back 4-1 of the pretensioning plate 4 is increased, the bow-shaped pretensioning plate 4 is elastically deformed to be flat, the distance between the top edges 4-2 at the two ends of the pretensioning plate 4 is enlarged, the top edges 4-2 at the two ends of the pretensioning plate 4 push the main nut 2 and the auxiliary nut 3 to rotate around the screw rod 1 in opposite directions respectively, and the main nut 2 and the auxiliary nut 3 are axially and oppositely preloaded, so that the axial gap between the main nut, the auxiliary nut and the screw rod is eliminated.

Specifically, referring to fig. 1 and 2, if the right-handed screw 1 is used, the pretensioning piece 4 must push the main nut 2 to rotate clockwise and push the sub-nut 3 to rotate counterclockwise (clockwise and counterclockwise are determined by fig. 2); if the left-handed screw 1 is used, the pre-tightening piece 4 must push the main nut 2 to rotate counterclockwise and push the sub-nut 3 to rotate clockwise (clockwise and counterclockwise are determined by fig. 2), and the right-handed screw 1 is taken as an example in this embodiment. The tightness of the threaded connecting piece at the opening of the pre-tightening hoop 5 is adjusted, so that the centripetal pressure of the pre-tightening hoop 5 on the bow back 4-1 of the pre-tightening piece 4 can be adjusted, and the pushing forces of pushing the main nut 2 and the auxiliary nut 3 to rotate in opposite directions around the screw rod 1 respectively by the top edges 4-2 at the two ends of the pre-tightening piece 4 are adjusted, so that the opposite pushing forces of the main nut 2 and the auxiliary nut 3, namely the pre-tightening force among the main nut 2, the auxiliary nut 3 and the screw rod 1, are adjusted. The screw connection piece at the opening of the pre-tightening clamp 5 is screwed, so that the centripetal pressure of the pre-tightening clamp 5 on the bow back 4-1 of the pre-tightening piece 4 is increased, the pre-tightening clamp 5 is elastically deformed, after the screw rod 1, the main nut 2 and the auxiliary nut 3 are worn, the pre-tightening clamp 5 is elastically deformed, the reserved elastic force can further push the pre-tightening piece 4 to elastically deform, so that the pre-tightening piece 4 tends to be more straight, the distance between the top edges 4-2 at the two ends of the pre-tightening piece 4 is further increased, the top edges 4-2 at the two ends of the pre-tightening piece 4 push the main nut 2 and the auxiliary nut 3 to further rotate around the screw rod 1 in opposite directions respectively, and therefore, the novel axial gaps generated by the abrasion between the main nut 2, the auxiliary nut 3 and the screw rod 1 are automatically eliminated.

In summary, the pretensioning mechanism applicable to the double-nut ball screw pair of the embodiment can eliminate the axial clearance between the main nut and the auxiliary nut and the screw; the pre-tightening force of the main nut 2 and the auxiliary nut 3 can be adjusted, the pre-tightening force is convenient to adjust, and only the threaded connecting piece is needed to be screwed or unscrewed; after the screw rod 1, the main nut 2 and the auxiliary nut 3 are worn, the axial gap between the screw rod and the main nut and the auxiliary nut due to wear can be automatically eliminated. Compared with the double-nut pre-tightening ball screw pair disclosed in the ZL201610943955.X patent, the ZL201610943955.X patent adopts the separation of the main nut and the auxiliary nut along the axial direction to the two sides to eliminate the axial clearance between the main nut and the auxiliary nut and the screw, and the invention adopts the axial opposite-pushing pre-tightening of the main nut 2 and the auxiliary nut 3 to eliminate the axial clearance between the main nut and the auxiliary nut and the screw, so that the moment for enabling the axis of the auxiliary nut 3 to generate angular displacement relative to the axis of the main nut 2 can not be generated.

In this embodiment, referring to fig. 1, the lengths of the main groove 2-2 and the sub groove 3-2 in the circumferential direction of the screw 1 are larger than the maximum length of the pretensioning plate 4 after being stretched and deformed, and preferably the lengths of the main groove 2-2 and the sub groove 3-2 in the circumferential direction of the screw 1 are equal. Defining a distance X between a main groove side wall 2-3 of the main groove 2-2 at a groove side opening of the auxiliary groove 3-2 along the circumferential direction of the screw 1 and an auxiliary groove side wall 3-3 of the auxiliary groove 3-2 at a groove side opening of the main groove 2-2 along the circumferential direction of the screw 1, wherein X is to ensure that a lower arched pretensioning piece 4 can be accommodated; defining a distance Y between a main groove side wall 2-3 of the main groove 2-2 at a groove side opening of the auxiliary groove 3-2 along the circumferential direction of the screw 1 and a distance Y between an auxiliary groove side wall 3-3 of the auxiliary groove 3-2 outside the groove side opening of the main groove 2-2 along the circumferential direction of the screw 1, and defining a distance Z between an auxiliary groove side wall 3-3 of the auxiliary groove 3-2 at a groove side opening of the main groove 2-2 and a main groove side wall 2-3 of the main groove 2-2 outside the groove side opening of the auxiliary groove 3-2 along the circumferential direction of the screw 1, wherein both Y and Z are larger than the maximum extension deformation of the pre-tightening piece 4; preferably, Y/X is equal to Z/X and the ratio is equal to 0.2 to 0.3 (including 0.2 and also including 0.3). The meaning of the design is as follows: ① Before the main nut 2 and the auxiliary nut 3 are oppositely propped and pre-tightened, the distance between the main groove side wall 2-3 of the main groove 2-2 at the groove side opening of the auxiliary groove 3-2 and the auxiliary groove side wall 3-3 of the auxiliary groove 3-2 at the groove side opening of the main groove 2-2 at the position along the circumferential direction of the screw 1 can be used for accommodating the bow-shaped pre-tightening piece 4 without elastic deformation; ② And the maximum stretching deformation of the pre-tightening piece 4 is ensured to be larger than that of the Y and Z, the relative rotation angular displacement of the main nut 2 and the auxiliary nut 3 is gradually increased along with the gradual increase of the stretching deformation of the pre-tightening piece 4, the Y and Z are gradually reduced, and the top pre-tightening of the main nut 2 and the auxiliary nut 3 is completed before the Y and Z are reduced to 1/3 of the original length.

In addition, referring to fig. 5-2, it should be noted that, in consideration of the convenience of processing, the pretensioning sheet 4 of the arch structure of the present embodiment may have an arch structure of a regular structure. Taking the arcuate structure of the pretensioning piece 4 of the arcuate structure of the present embodiment as an example, in order to improve the efficiency of transforming the pressure applied to the pretensioning piece 4 by the pretensioning hoop 5 into the deformation of the pretensioning piece 4, for the pretensioning piece 4 of the arcuate structure, an included angle α formed between the center of the circle corresponding to the pretensioning piece 4 of the arcuate structure and the top edges 4-2 at both ends of the pretensioning piece 4 is defined, and α=120 ° to 140 °, and for the pretensioning piece 4 within this angle range, the efficiency of deforming the pretensioning piece 4 by pressing the pretensioning piece 4 by the pretensioning hoop 5 to eliminate the axial gap between the lead screw 1 and the main nut 2 and the sub nut 3 can be improved.

Example 2:

Referring to fig. 3 and 4, the structure of the double-nut ball screw pair provided in this embodiment is substantially the same as that of embodiment 1, except that the end face of the auxiliary nut 3 facing one end of the main nut 2 is provided with a conical hole 3-1 coaxial with the axis of the auxiliary nut 3; on the end face of the main nut 2 toward one end of the sub nut 3, there is provided a truncated cone coaxial with the axis of the main nut 2, the truncated cone face 2-1 is coaxial with the axis of the main nut 2 and protrudes from the end face of the main nut 2 located at one end of the sub nut 3 (in other words, on the end face of the main nut 2 located at one end of the sub nut 3, there is provided a truncated cone face 2-1 protruding with the axis of the main nut 2), the truncated cone face 2-1 on the main nut 2 has the same angle of taper as the truncated cone 3-1 on the sub nut 3, and the truncated cone on the main nut 2 is inserted into the truncated cone 3-1 on the sub nut 3 and the truncated cone face 2-1 is brought into contact with and forms a fit with the truncated cone 3-1 on the sub nut 3.

The embodiment has the specific beneficial effects that: referring to fig. 3 and 4, the conical frustum on the main nut 2 is inserted into the conical hole 3-1 on the auxiliary nut 3 to form a fit, so that the main nut 2 is positioned radially to the auxiliary nut 3, and good coaxiality of the axis of the main nut 2 and the axis of the auxiliary nut 3 under the action of opposite pre-tightening force is ensured. Obviously, the end face of the main nut 2 at one end of the auxiliary nut 3 is provided with a conical hole 3-1 coaxial with the axis of the main nut 2, the end face of the auxiliary nut 3 at one end of the main nut 2 is provided with a conical platform coaxial with the axis of the auxiliary nut 3, and the conical surface 2-1 of the conical platform on the auxiliary nut 3 has the same cone angle as the conical hole 3-1 on the main nut 2, so that the beneficial effects can be obtained.

Example 3:

Referring to fig. 6, in the structure of the double-nut ball screw assembly of embodiment 1 or embodiment 2, a flange 5-4 is provided at a portion where the pretensioner 5 contacts with the pretensioner plate 4, so that a cross section of the pretensioner 5 at the portion is in a "╔ ╗" groove shape. The improved beneficial effects are that: the bow back 4-1 of the pre-tightening piece 4 is embedded into the groove of the pre-tightening clamp 5 in the shape of ╔ ╗, so that the pre-tightening piece 4 can give the pre-tightening clamp 5 the axial positioning of the screw rod 1, and the pre-tightening clamp 5 can be prevented from being axially displaced along the screw rod 1 to be separated from contact with the pre-tightening piece 4. While the axial positioning of the pre-tightening tab 4 relative to the screw shaft 1 is given by the combination of the main groove 2-2 and the sub-groove 3-2, specifically, referring to fig. 1, the groove side wall of the main groove 2-2 which is open at the side of the groove (i.e., the groove side wall of the main groove 2-2 which is perpendicular to the axis of the main nut 2) gives the pre-tightening tab 4a left-side axial positioning, and the sub-groove 3-2 which is open at the side of the groove (i.e., the groove side wall of the sub-groove 3-2 which is perpendicular to the axis of the sub-nut 3) gives the pre-tightening tab 4a right-side axial positioning (the left-right-side orientation of the pre-tightening tab 4 is determined by fig. 1).

Example 4:

Referring to fig. 7-1, fig. 7-2, fig. 8, and fig. 9, the pretensioner plate 4 of the double-nut ball screw assembly provided in this embodiment can be improved on the basis of the structure of the double-nut ball screw assembly of embodiment 1 or embodiment 2. At least one pair of fins 4-3 is provided on the face of the pretensioning piece 4 that contacts the pretensioning clip 5 (in other words, on the face of the pretensioning piece 4 having the bow-back 4-1) and along the circumferential direction of the screw shaft 1 (i.e., the length direction of the pretensioning piece 4). The pair of fins 4-3 is two fins 4-3 symmetrically arranged, and further, the pair of fins 4-3 includes two fins 4-3 symmetrically arranged on both sides of the pre-tightening plate 4 in the axial direction of the screw 1 (i.e., the width direction of the pre-tightening plate 4).

The pair of fins 4-3 symmetrically disposed on both edges of the pretensioning piece 4 in the axial direction of the screw shaft 1 includes two fins 4-3 sandwiching the pretensioning strap 5 and having the two fins 4-3 respectively abutted against the pretensioning strap 5, in other words, the pretensioning strap 5 passes between the fins 4-3 symmetrically disposed on both edges of the pretensioning piece 4 in the axial direction of the screw shaft 1. Referring to fig. 7-1 and 7-2, in this embodiment, two pairs of fins 4-3 are preferably disposed on the pre-tightening plate 4 along the circumferential direction of the screw 1, specifically, the two pairs of fins 4-3 are respectively located on two sides of the bow back 4-1 of the pre-tightening plate 4 along the circumferential direction of the screw 1 (i.e. the length direction of the pre-tightening plate 4).

In addition, referring to fig. 7-2, it should be noted that, in the pretensioning sheet 4 of the present embodiment, the pretensioning sheet 4 provided with the arch structure of the fins 4-3 may have a regular structure in view of convenience of processing. Taking the example that the pre-tightening piece 4 provided with the arch structure of the fin 4-3 adopts a regular structure as the pre-tightening piece 4, in order to improve the efficiency of transforming the pressure applied by the pre-tightening hoop 5 to the pre-tightening piece 4 into the deformation of the pre-tightening piece 4, for the pre-tightening piece 4 of the "Λ" structure, the included angle formed between two sides of the bow back 4-1 of the pre-tightening piece 4 of the "Λ" structure along the circumferential direction of the screw rod 1 is defined as beta, then beta=90 DEG-110 DEG, and the pre-tightening piece 4 in the angle range can improve the efficiency of deforming the pre-tightening piece 4 by pressing the pre-tightening hoop 5 to eliminate the axial gap between the screw rod and the main nut 3 and the auxiliary nut 3.

The specific beneficial effects of the structure of the pretensioning piece 4 of the structure of the double-nut ball screw pair in this embodiment are: referring to fig. 8, the pretensioning tab 4 is arranged to clamp the pretensioning tab 5 between two symmetrical fins 4-3 by providing at least one pair of fins 4-3, so that the pretensioning tab 5 is positioned in the axial direction of the lead screw 1. In addition, the fins 4-3 arranged on the pre-tightening piece 4 can play a role of reinforcing ribs, so that the strength of the two sides of the bow back 4-1 of the pre-tightening piece 4 along the circumferential direction of the screw rod 1 is enhanced, when the pre-tightening piece 4 is subjected to the centripetal pressure of the pre-tightening hoop 5 to stretch and deform, the pre-tightening piece 4 is not easy to generate distortion and instability, and the stretching and deforming of the pre-tightening piece 4 is concentrated on the bow back 4-1.

With the above-described preferred embodiments according to the present invention as an illustration, the above-described descriptions can be used by persons skilled in the relevant art to make various changes and modifications without departing from the scope of the technical idea of the present invention. The technical scope of the present invention is not limited to the description, but must be determined according to the scope of claims.

In the description of the present invention, it should be understood that the terms "orientation" or "positional relationship" are based on the orientation or positional relationship shown in the drawings, and are merely for convenience of description and to simplify the description, rather than to indicate or imply that the apparatus or elements referred to must have a particular orientation, be constructed and operate in a particular orientation, and therefore should not be construed as limiting the invention.

In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be directly connected or indirectly connected through an intermediate medium. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.

In the description of the present invention, it should be noted that, directions or positional relationships indicated by terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., are directions or positional relationships based on those shown in the drawings, or are directions or positional relationships conventionally put in use of the inventive product, are merely for convenience of describing the present invention and simplifying the description, and are not indicative or implying that the apparatus or element to be referred to must have a specific direction, be constructed and operated in a specific direction, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," and the like are used merely to distinguish between descriptions and should not be construed as indicating or implying relative importance.

Furthermore, the terms "horizontal," "vertical," "overhang," and the like do not denote a requirement that the component be absolutely horizontal or overhang, but rather may be slightly inclined. As "horizontal" merely means that its direction is more horizontal than "vertical", and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.

In the present invention, unless expressly stated or limited otherwise, a first feature may include first and second features directly contacting each other, either above or below a second feature, or through additional features contacting each other, rather than directly contacting each other. Moreover, the first feature being above, over, and on the second feature includes the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature is higher in level than the second feature. The first feature being below, beneath, and beneath the second feature includes the first feature being directly below and obliquely below the second feature, or simply indicates that the first feature is less level than the second feature.

Claims (10)

1. The utility model provides a pretension mechanism suitable for double nut ball screw pair which characterized in that includes:

The main groove (2-2) is formed in a main nut (2) sleeved on a screw (1) of the double-nut ball screw pair, the main groove (2-2) is formed in the outer peripheral surface of the main nut (2) facing one side of an auxiliary nut (3) sleeved on the screw (1) of the double-nut ball screw pair, and the main groove (2-2) is provided with a groove side opening and the groove side opening faces the auxiliary nut (3);

The auxiliary groove (3-2) is formed in the auxiliary nut (3), the auxiliary groove (3-2) is formed in the outer peripheral surface of one side, facing the main nut (2), of the auxiliary nut (3), and the auxiliary groove (3-2) is provided with a groove side opening which faces the main nut (2); the groove side opening of the auxiliary groove (3-2) is suitable for being abutted with the groove side opening of the main groove (2-2) along the axial direction of the screw (1), and the auxiliary groove (3-2) is suitable for being distributed in a staggered manner with the main groove (2-2) along the circumferential direction of the screw (1);

The pre-tightening piece (4) is made of elastic materials, and the pre-tightening piece (4) is of an arch structure; the pre-tightening piece (4) is suitable for being embedded in the main groove (2-2) and the auxiliary groove (3-2) at the same time, and the bow back (4-1) of the pre-tightening piece (4) is opposite to the main groove (2-2) and the auxiliary groove (3-2); and one end of the pre-tightening piece (4) along the circumferential direction of the screw (1) is suitable for being abutted against one main groove side wall (2-3) of the main groove (2-2), and the other end of the pre-tightening piece (4) along the circumferential direction of the screw (1) is suitable for being abutted against one auxiliary groove side wall (3-3) of the auxiliary groove (3-2); the pre-tightening piece (4) is in a relative distribution relationship with the side wall (2-3) of the main groove (2-2) and the side wall (3-3) of the auxiliary groove (3-2) of the main groove (2-2) which are respectively propped against the two ends of the screw rod (1) along the circumferential direction;

The pre-tightening hoop (5) is of an annular structure with an opening, and the pre-tightening hoop (5) is suitable for being arranged around the butt joint position of the main nut (2) and the auxiliary nut (3) in a surrounding manner and is pressed against the pre-tightening piece (4); and a threaded connecting piece consisting of a bolt and an adjusting nut (6) is arranged at the opening of the pre-tightening hoop (5).

2. The pretensioning mechanism for a double-nut ball screw assembly according to claim 1, wherein a slight gap exists between one end of the pretensioning piece (4) in the axial direction of the screw (1) and the groove side wall of the main groove (2-2) which is far from the groove side opening thereof; and

A small gap exists between the other end part of the pre-tightening piece (4) along the axial direction of the screw rod (1) and the side wall of the auxiliary groove (3-2) away from the side opening of the groove.

3. Pretensioning mechanism for a double-nut ball screw assembly according to any one of claims 1 or 2, characterized in that one main groove side wall (2-3) of the main groove (2-2) is located at the groove side opening of the sub groove (3-2) in the circumferential direction of the screw (1), and the other main groove side wall (2-3) of the main groove (2-2) is located outside the groove side opening of the sub groove (3-2) in the circumferential direction of the screw (1); and

One auxiliary groove side wall (3-3) of the auxiliary groove (3-2) is positioned at the groove side opening of the main groove (2-2) along the circumferential direction of the screw (1), and the other auxiliary groove side wall (3-3) of the auxiliary groove (3-2) is positioned outside the groove side opening of the main groove (2-2) along the circumferential direction of the screw (1).

4. Pretensioning mechanism for a double-nut ball screw assembly according to claim 1, characterized in that the groove lengths of the main groove (2-2) and the sub groove (3-2) in the circumferential direction along the screw (1) are equal or unequal; and

The groove widths of the main groove (2-2) and the auxiliary groove (3-2) in the axial direction along the screw (1) are equal or unequal.

5. Pretensioning mechanism suitable for double-nut ball screw assembly according to claim 1, characterized in that a pair of said main grooves (2-2) is provided on said main nut (2), and a pair of said auxiliary grooves (3-2) is provided on said auxiliary nut (3), correspondingly; and

The pretensioning mechanism comprises a pair of pretensioning pieces (4).

6. The pretensioning mechanism according to claim 1, characterized in that a pair of flanges (5-4) adapted to abut against both ends of the pretensioning piece (4) in the axial direction of the screw (1) are provided at the portion where the pretensioning piece (5) contacts the pretensioning piece (4), respectively, so that the portion where the pretensioning piece (5) contacts the pretensioning piece (4) has a groove shape of "╔ ╗".

7. Pretensioning mechanism suitable for double-nut ball screw pair according to claim 1, characterized in that at least one pair of fins (4-3) is provided on the pretensioning piece (4) along the circumferential direction of the screw (1);

two fins (4-3) of the pair of fins (4-3) are positioned on the surface of the pre-tightening piece (4) contacted with the pre-tightening hoop (5);

The pretensioning band (5) is adapted to pass between two fins (4-3) of a pair of the fins (4-3) and to bring the fins (4-3) into abutment with the pretensioning band (5).

8. The pretensioning mechanism for a double-nut ball screw pair according to claim 7, wherein two pairs of fins (4-3) are provided on the pretensioning piece (4) along the circumferential direction of the screw (1), and the two pairs of fins (4-3) are located on both sides of the bow back (4-1) of the pretensioning piece (4) along the circumferential direction of the screw (1), respectively.

9. A double-nut ball screw assembly, comprising: a screw (1), a main nut (2) and a sub-nut (3) which are sleeved on the screw (1) in series, and a pretensioning mechanism according to any one of claims 1 to 8.

10. The double-nut ball screw assembly according to claim 9, wherein a conical hole (3-1) coaxial with the axis of the auxiliary nut (3) is formed in the end face of the auxiliary nut (3) facing one end of the main nut (2);

a cone frustum coaxial with the axis of the main nut (2) is arranged on the end face of the main nut (2) facing one end of the auxiliary nut (3);

the conical surface (2-1) of the truncated cone on the main nut (2) has the same cone angle as the conical hole (3-1) on the auxiliary nut (3); and

The cone frustum on the main nut (2) is inserted into the cone hole (3-1) on the auxiliary nut (3) and the cone surface (2-1) of the cone frustum is contacted with the cone hole (3-1) on the auxiliary nut (3) to form fit.