Two-way bearing double-nut ball screw pair, operation control method and pretightening force adjusting method thereof and one-way bearing nut ball screw pair

Abstract

The invention discloses a two-way bearing double-nut ball screw pair, an operation control method and a pre-tightening force adjusting method thereof, a one-way bearing nut ball screw pair and a two-way bearing double-nut ball screw pair. The two-way bearing double-nut ball screw pair comprises a lead screw, a first nut, a first pre-tightening mechanism, a second pre-tightening mechanism, a second nut and a nut seat. The first nut and the second nut are installed on the lead screw in a sleeving mode, the nut base supports the outer sides of the first nut and the second nut, and the nut base limits the first nut and the second nut in the axial direction. A first locking mechanism and a second locking mechanism are installed at the two ends of the nut base respectively. The first locking mechanism is used for controlling the freedom degree of the first nut in the rotating direction. The second locking mechanism is used for controlling the freedom degree of the second nut in the rotating direction. The first pre-tightening mechanism is used for supporting the first nut in the pre-tightening rotation direction. The second pre-tightening mechanism is used for supporting the second nut in the pre-tightening rotation direction. The operation smoothness of the lead screw pair can be effectively improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of transmission devices, and particularly relates to a double-nut ball screw pair with bidirectional load-bearing, its operation control method and pre-tightening force adjustment method, and a nut ball screw pair with unidirectional load-bearing. Background Art

[0002] Due to the machining accuracy errors and assembly errors of the ball screw and the nut, it is often necessary to apply a pre-tightening force to the nut to eliminate the axial clearance, increase the system rigidity, and improve the positioning accuracy.

[0003] At present, a double-nut structure is used to achieve pre-tightening force adjustment, mainly including gasket type, positioning pin type, differential tooth type, spring type, etc. The first three mainly generate pre-tightening force by making a set of raceways and steel balls displace axially relative to another set of raceways and steel balls to ensure the transmission accuracy.

[0004] However, these three are all rigid connections, that is, after the screw pair leaves the factory, the relative displacement between the two sets of raceways of the double nuts has been adjusted. When the pitch diameter of the screw raceway increases and the lead accuracy changes, the pre-tightening force will be too large or too small. An increase in the pre-tightening force will reduce the service life of the screw pair, and a decrease will reduce the transmission accuracy. Secondly, this too-large or too-small change in the pre-tightening force will also affect the smooth operation of the screw pair.

[0005] The spring type adds an elastic pre-tightening force between the double nuts through an elastic connection method. Although it can let the elastic pre-tightening force offset part of the changes in the pitch diameter and lead of the screw raceway, currently this type of structure can only bear loads unidirectionally. Because the load-bearing directions of the double-nut groups in the double-nut structure are different, and the load-bearing nuts in the double-nut groups are also different, that is, when the double-nut group bears loads in a certain direction, one nut bears the load and the other nut mainly provides the pre-tightening force. When the load-bearing direction changes, the bearing capacity will be transmitted to the spring pre-tightening part, resulting in the phenomenon of unilateral nut ball failure. The nut that provided the pre-tightening force before will also become the load-bearing nut. Because of this characteristic, the elastic connection method can only bear loads unidirectionally.

[0006] There is an urgent need for a double-nut ball screw pair that can bear loads unidirectionally / bidirectionally and has a small pre-tightening force change fluctuation when the pitch diameter of the screw raceway increases and the lead accuracy changes. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a double-nut ball screw pair with bidirectional load-bearing, its operation control method and pre-tightening force adjustment method, and a nut ball screw pair with unidirectional load-bearing for the deficiencies in the above-mentioned prior art, which can have a small pre-tightening force change fluctuation when the pitch diameter of the screw raceway increases and the lead accuracy changes, and can effectively improve the smooth operation of the screw pair.

[0008] The first aspect of the present invention discloses a double-nut ball screw pair with bidirectional load-bearing, comprising: a screw rod, a first nut, a first preloading mechanism, a second preloading mechanism, a second nut and a nut seat; The first nut and the second nut are sleeved and installed on the screw rod, and the nut seat supports the outer sides of the first nut and the second nut, and the nut seat limits the first nut and the second nut axially; A first locking mechanism and a second locking mechanism are respectively installed at both ends of the nut seat; The first locking mechanism is used to control the freedom degree of the rotation direction of the first nut; The second locking mechanism is used to control the freedom degree of the rotation direction of the second nut; The first preloading mechanism includes a first stop ring and a first elastic member. The first stop ring is coaxially installed with the first nut. The first elastic member is installed on the nut seat. The telescopic direction of the first elastic member is perpendicular to the axis of the first stop ring. There is a convex structure on the first stop ring, and the first elastic member abuts against the convex structure; The second preloading mechanism includes a second stop ring and a second elastic member. The second stop ring is coaxially installed with the second nut. The second elastic member is installed on the nut seat. The telescopic direction of the second elastic member is perpendicular to the axis of the second stop ring. There is a convex structure on the second stop ring, and the second elastic member abuts against the convex structure.

[0009] For the above-mentioned double-nut ball screw pair with bidirectional load-bearing, the first locking mechanism is a first electromagnetic brake, and the second locking mechanism is a second electromagnetic brake; a first connecting piece fixed to the brake disc of the first electromagnetic brake is installed at the front end of the first nut, and a second connecting piece fixed to the brake disc of the first electromagnetic brake is installed at the rear end of the second nut.

[0010] For the above-mentioned double-nut ball screw pair with bidirectional load-bearing, the first elastic member includes a guide cylinder, an adjusting nut, a disc spring group, a slider and a steel ball; the root of the guide cylinder is installed on the adjusting nut, the adjusting nut is threadedly connected to a stud, and the stud is detachably connected to the nut seat; the disc spring group and the slider are installed in the guide cylinder, the root of the disc spring group is connected to the root of the guide cylinder, the slider is connected to the front end of the disc spring group, a tapered card slot is provided at the front end of the slider, the steel ball is located in the tapered card slot, the front side of the steel ball or a part of the front side of the slider is outside the guide cylinder, and the steel ball abuts against the convex structure on the first stop ring.

[0011] For the above-mentioned double-nut ball screw pair with bidirectional load-bearing, the first elastic member and the second elastic member have the same structure.

[0012] For the above-mentioned double-nut ball screw pair with bidirectional load-bearing, the first nut has an axle shoulder structure, thrust cylindrical roller bearings are arranged on both sides of the axle shoulder structure, and needle roller bearings are arranged on the circumferential side of the axle shoulder structure.

[0013] For the above-mentioned double-nut ball screw pair with bidirectional load-bearing, the nut two has a shoulder structure, thrust cylindrical roller bearings are arranged on both sides of the shoulder structure, and needle bearings are arranged on the circumferential side of the shoulder structure.

[0014] The second aspect of the present invention discloses an operation control method for the double-nut ball screw pair with bidirectional load-bearing as described in the first aspect, including the following steps: Before the screw starts to run, control the locking mechanism one to lock the nut one so that the nut one cannot rotate, and control the locking mechanism two to lock the nut two so that the nut two cannot rotate; Before the operation of the screw switches from uniform speed to deceleration, control the locking mechanism one to lock the nut one so that the nut one cannot rotate, and control the locking mechanism two to lock the nut two so that the nut two cannot rotate.

[0015] The above operation control method includes the following steps: After the screw starts to run, if the nut one is the working nut, control the locking mechanism two to open so that the nut two can rotate; After the screw starts to run, if the nut two is the working nut, control the locking mechanism one to open so that the nut one can rotate.

[0016] The third aspect of the present invention discloses a pre-tightening force adjustment method for the double-nut ball screw pair with bidirectional load-bearing as described in the first aspect, including the following steps: In the initial state, rotate the nut one and the nut two so that the nut one and the nut two reach the initial pre-tightening state; Then, install the elastic member one and the elastic member two, and adjust the supporting forces of the elastic member one and the elastic member two so that the nut one and the nut two rotate a certain angle in opposite rotation directions respectively to achieve pre-tightening force adjustment.

[0017] For the above pre-tightening force adjustment method, after installing the elastic member one and the elastic member two, only adjust the supporting force of the elastic member one or the elastic member two so that the nut one and the nut two rotate a certain angle in opposite rotation directions respectively to achieve pre-tightening force adjustment.

[0018] The fourth aspect of the present invention discloses a one-way load-bearing nut ball screw pair, including: a screw, a nut one, a pre-tightening mechanism one and a nut seat; The nut one is sleeved and installed on the screw, the nut seat supports the outside of the nut one, and the nut seat limits the nut one axially; One end of the nut seat is provided with a locking mechanism one; The locking mechanism one is used to control the degree of freedom of the rotation direction of the nut one; The preloading mechanism 1 includes a retaining ring 1 and an elastic member 1. The retaining ring 1 is coaxially installed with the nut. The elastic member 1 is installed on the nut seat. The telescopic direction of the elastic member 1 is perpendicular to the axis of the retaining ring 1. The retaining ring 1 has a convex structure, and the elastic member 1 abuts against the convex structure.

[0019] Compared with the prior art, the present invention has the following advantages: Instead of applying a thrust axially to the nut to generate a preloading force in the traditional preloading method, the nut is pre-rotated by a certain angle to generate a preloading force, and the elastic member is used to keep the nut in the pre-rotated state to maintain the preloading force. When the pitch diameter of the lead screw raceway increases and the lead accuracy changes, the elastic force of the elastic member is released to allow the nut to rotate by a certain angle, so as to continuously maintain the preloading. The change of the preloading force fluctuates little, which can effectively improve the smoothness of the operation of the lead screw pair.

[0020] The technical solution of the present invention will be further described in detail below with reference to the drawings and embodiments. Brief Description of the Drawings

[0021] Figure 1 It is a schematic structural diagram of Embodiment 1 of the present invention.

[0022] Figure 2 It is a schematic structural diagram of the preloading mechanism of the present invention.

[0023] Figure 3 It is a schematic diagram of the principle of the preloaded state of Nut 1 and Nut 2 of the present invention.

[0024] Figure 4 It is a schematic structural diagram of Embodiment 4 of the present invention.

[0025] Description of the Reference Numerals: 1—Lead screw 2—First nut 3—First preloading mechanism 4—Second preloading mechanism 5—Second nut 6—Nut seat 7—First locking mechanism 8—Second locking mechanism 9—First stop ring 10—First elastic part 11—Second stop ring 12—Second elastic part 13—First connecting piece 14—Second connecting piece 15—Thrust cylindrical roller bearing 16—Needle bearing 10-1—Guide tube 10-2—Adjusting nut 10-3—Disc spring group 10-4—Slider 10-5—Steel ball Detailed Embodiment

[0026] Embodiment 1: As Figure 1As shown in the figure, a double-nut ball screw pair with bidirectional load-bearing includes: a lead screw 1, a first nut 2, a first preloading mechanism 3, a second preloading mechanism 4, a second nut 5, and a nut seat 6; the first nut 2 and the second nut 5 are sleeved and installed on the lead screw 1, the nut seat 6 supports the outer sides of the first nut 2 and the second nut 5, and the nut seat 6 limits the first nut 2 and the second nut 5 axially; locking mechanisms 7 and 8 are respectively installed at both ends of the nut seat 6; the locking mechanism 7 is used to control the freedom degree of the rotation direction of the first nut 2; the locking mechanism 8 is used to control the freedom degree of the rotation direction of the second nut 5; the first preloading mechanism 3 includes a first stop ring 9 and a first elastic member 10, the first stop ring 9 is coaxially installed with the first nut 2, the first elastic member 10 is installed on the nut seat 6, the telescopic direction of the first elastic member 10 is perpendicular to the axis of the first stop ring 9, the first stop ring 9 has a protruding structure, and the first elastic member 10 abuts against the protruding structure; the second preloading mechanism 4 includes a second stop ring 11 and a second elastic member 12, the second stop ring 11 is coaxially installed with the second nut 5, the second elastic member 12 is installed on the nut seat 6, the telescopic direction of the second elastic member 12 is perpendicular to the axis of the second stop ring 11, the second stop ring 11 has a protruding structure, and the second elastic member 12 abuts against the protruding structure.

[0027] In this embodiment, the locking mechanism 7 is a first electromagnetic brake, and the locking mechanism 8 is a second electromagnetic brake; a first connecting piece 13 fixed to the brake disc of the first electromagnetic brake is installed at the front end of the first nut 2, and a second connecting piece 14 fixed to the brake disc of the first electromagnetic brake is installed at the rear end of the second nut 5.

[0028] It should be noted that the advantage of using an electromagnetic brake as the locking mechanism is that it can achieve high-precision control and facilitate the rapid switching between the locked and open states.

[0029] Those skilled in the art should be clear that the locking mechanism can also be a similar structure based on the clutch principle.

[0030] Such as Figure 2As shown in the figure, in this embodiment, the first elastic member 10 includes a guiding cylinder 10-1, an adjusting nut 10-2, a disc spring group 10-3, a slider 10-4 and a steel ball 10-5; the root of the guiding cylinder 10-1 is installed on the adjusting nut 10-2, the adjusting nut 10-2 is threadedly connected to a stud, and the stud is detachably connected to a nut seat 6; the disc spring group 10-3 and the slider 10-4 are installed in the guiding cylinder 10-1, the root of the disc spring group 10-3 is connected to the root of the guiding cylinder 10-1, the slider 10-4 is connected to the front end of the disc spring group 10-3, the front end of the slider 10-4 has a tapered card slot, the steel ball 10-5 is located in the tapered card slot, and the front side of the steel ball 10-5 or a partial front side of the slider 10-4 is outside the guiding cylinder 10-1, and the steel ball 10-5 abuts against the convex structure of the first retaining ring 9.

[0031] In this embodiment, the structures of the first elastic member 10 and the second elastic member 12 are the same.

[0032] In actual use, by rotating the adjusting nut 10-2 to adjust the distance between the adjusting nut and the convex structure of the retaining ring, the magnitude of the abutting force is further adjusted, and indirectly the magnitude of the pre-tightening force is adjusted.

[0033] It should be noted that the guiding cylinder can be a separate part, or the wall thickness of the nut seat can be deepened, and a guiding cylinder structure can be provided on the nut seat 6.

[0034] In this embodiment, the first nut 2 has a shoulder structure, thrust cylindrical roller bearings 15 are arranged on both sides of the shoulder structure, and needle roller bearings 16 are arranged on the circumferential side of the shoulder structure.

[0035] In this embodiment, the second nut 5 has a shoulder structure, thrust cylindrical roller bearings 15 are arranged on both sides of the shoulder structure, and needle roller bearings 16 are arranged on the circumferential side of the shoulder structure.

[0036] It should be noted that since both the first nut 2 and the second nut 5 may rotate with the lead screw 1, the nut has a shoulder structure, thrust cylindrical roller bearings 15 are arranged on both sides of the shoulder structure to adapt to rotation and axial thrust, and needle roller bearings 16 are arranged on the circumferential side of the shoulder structure to adapt to rotation.

[0037] Embodiment 2: An operation control method for a double-nut ball screw pair with bidirectional load bearing includes the following steps:

[0038] Before the lead screw 1 starts to run, control the first locking mechanism 7 to lock the first nut 2 so that the first nut 2 cannot rotate, and control the second locking mechanism 8 to lock the second nut 5 so that the second nut 5 cannot rotate; After the lead screw 1 starts to run, if the first nut 2 is the working nut, control the second locking mechanism 8 to open so that the second nut 5 can rotate; After the lead screw 1 starts to run, if the second nut 5 is the working nut, the first locking mechanism 7 is controlled to open so that the first nut 2 can rotate; Before the operation of the lead screw 1 switches from uniform speed to deceleration, the first locking mechanism 7 is controlled to lock the first nut 2 so that the first nut 2 cannot rotate, and the second locking mechanism 8 is controlled to lock the second nut 5 so that the second nut 5 cannot rotate.

[0039] It should be noted that considering the inertial effect of the nut seat 6 at the moment when the lead screw 1 starts to run and at the moment of switching from uniform speed to deceleration, before and after the speed switching, both the first locking mechanism 7 and the second locking mechanism 8 are locked, so that the first nut 2 and the second nut 5 are rigidly connected to the nut seat 6 and cannot rotate, keeping their pre-tightening positions unchanged, thereby fully improving the running accuracy of the nut seat 6.

[0040] Embodiment 3: As Figure 3 shown, a method for adjusting the pre-tightening force of a double-nut ball screw pair with bidirectional load-bearing includes the following steps:

[0041] In the initial state, rotate the first nut 2 and the second nut 5 so that the first nut 2 and the second nut 5 reach the initial pre-tightening state; Then, install the first elastic member 10 and the second elastic member 12, and adjust the supporting forces of the first elastic member 10 and the second elastic member 12 so that the first nut 2 and the second nut 5 rotate a certain angle in opposite rotation directions respectively to achieve pre-tightening force adjustment.

[0042] It should be noted that in the initial state, keep the lead screw 1 stationary and rotate the first nut 2. During the rotation of the first nut 2, it moves axially along the lead screw 1. Assuming that the first nut 2 moves to the left, at this time, the balls of the first nut 2 will be squeezed to the left side of the raceway to be tightened, forming pre-tightening; similarly, the second nut 5 moves to the right, and at this time, the balls of the second nut 5 will be squeezed to the right side of the raceway to be tightened, forming pre-tightening; in practice, due to the nut seat 6, when the first nut 2 and the second nut 5 are rotated in opposite directions respectively, the first nut 2 and the second nut 5 can only rotate a small angle and cannot actually move axially along the lead screw 1, but only drive the balls to press against one side of the raceway to form pre-tightening. At this time, install the first elastic member 10 and the second elastic member 12 to keep the first nut 2 and the second nut 5 in the pre-tightening state, and the pre-tightening can be completed. If the pre-tightening force needs to be adjusted, the supporting forces of the first elastic member 10 and the second elastic member 12 can be adjusted so that the first nut 2 and the second nut 5 rotate a certain angle in opposite rotation directions respectively to achieve pre-tightening force adjustment.

[0043] In this embodiment, after installing the first elastic member 10 and the second elastic member 12, only adjust the supporting force of the first elastic member 10 or the second elastic member 12 so that the first nut 2 and the second nut 5 rotate a certain angle in opposite rotation directions respectively to achieve pre-tightening force adjustment.

[0044] It should be noted that the first retaining ring 9 and the second retaining ring 11 are arranged side by side between the first nut 2 and the second nut 5. The rotation direction of the first retaining ring 9 supported by the first elastic member 10 is opposite to the rotation direction of the second retaining ring 11 supported by the second elastic member 12. As shown in the figure, when the first retaining ring 9 is rotated by the support of the first elastic member 10, the first nut 2 will move to the left, and when the second retaining ring 11 is rotated by the support of the second elastic member 12, the second nut 5 will move to the right; After the first elastic member 10 and the second elastic member 12 are installed, only the first elastic member 10 is adjusted. If the support force of the first elastic member 10 is increased by adjustment, at this time, the first nut 2 is supported and rotated counterclockwise, having a tendency to move to the left. Under the connection action of the nut seat 6, the second nut 5 also has a tendency to move to the left. At this time, the second nut 5 will rotate counterclockwise, and the second retaining ring 11 will rotate counterclockwise synchronously to compress the second elastic member 12, indirectly adjusting the support force of the second elastic member 12 on the retaining ring. Therefore, in practice, when adjusting the pre-tightening force, only the support force of the first elastic member 10 or the second elastic member 12 can be adjusted.

[0045] Embodiment 4: As Figure 4 shown, a one-way load-bearing nut ball screw pair includes: a lead screw 1, a first nut 2, a first pre-tightening mechanism 3, and a nut seat 6; the first nut 2 is sleeved and installed on the lead screw 1, the nut seat 6 supports the outside of the first nut 2, and the nut seat 6 limits the first nut 2 axially; one end of the nut seat 6 is provided with a first locking mechanism 7; the first locking mechanism 7 is used to control the degree of freedom of the rotation direction of the first nut 2; the first pre-tightening mechanism 3 includes a first retaining ring 9 and a first elastic member 10. The first retaining ring 9 is coaxially installed with the first nut 2. The first elastic member 10 is installed on the nut seat 6. The telescopic direction of the first elastic member 10 is perpendicular to the axis of the first retaining ring 9. The first retaining ring 9 has a convex structure, and the first elastic member 10 supports on the convex structure.

[0046] In this embodiment, the first locking mechanism 7 is an electromagnetic brake 1. A first connecting piece 13 fixed to the brake disc of the electromagnetic brake 1 is installed at the front end of the first nut 2.

[0047] In this embodiment, the first elastic member 10 includes a guiding cylinder 10-1, an adjusting nut 10-2, a disc spring group 10-3, a slider 10-4 and a steel ball 10-5. The root of the guiding cylinder 10-1 is mounted on the adjusting nut 10-2, and the adjusting nut 10-2 is threadedly connected to a stud, and the stud is detachably connected to the nut seat 6. The disc spring group 10-3 and the slider 10-4 are mounted inside the guiding cylinder 10-1. The root of the disc spring group 10-3 is connected to the root of the guiding cylinder 10-1, and the slider 10-4 is connected to the front end of the disc spring group 10-3. A conical card slot is provided at the front end of the slider 10-4, and the steel ball 10-5 is located in the conical card slot. The front side of the steel ball 10-5 or a partial front side of the slider 10-4 is outside the guiding cylinder 10-1, and the steel ball 10-5 abuts against the protruding structure of the first retaining ring 9.

[0048] It should be noted that for a one-way load-bearing nut ball screw pair, during installation, assuming that the running direction of the nut seat 6 is to move to the right, when the nut seat 6 and the first nut 2 are installed at the leftmost end of the lead screw 1, the left side of the nut seat 6 is limited by an external device or a shoulder structure on the lead screw 1. Then, the first retaining ring 9 is rotated to pre-tighten the first nut 2, and then the first elastic member 10 is installed to keep the first nut 2 in a pre-tightened state.

[0049] The above are only preferred embodiments of the present invention, and do not impose any limitations on the present invention. Any simple modifications, changes, and equivalent structural changes made to the above embodiments according to the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A double-nut ball screw pair with bidirectional load-bearing, characterized in that, Comprising: A lead screw, a first nut, a first preloading mechanism, a second preloading mechanism, a second nut and a nut seat; The first nut and the second nut are sleeved and installed on the lead screw, the nut seat supports the outer sides of the first nut and the second nut, and the nut seat limits the first nut and the second nut axially; A first locking mechanism and a second locking mechanism are respectively installed at both ends of the nut seat; The first locking mechanism is used to control the freedom degree of the rotation direction of the first nut; The second locking mechanism is used to control the freedom degree of the rotation direction of the second nut; The first preloading mechanism is used to support and push the first nut in the preloading rotation direction; The second preloading mechanism is used to support and push the second nut in the preloading rotation direction.

2. The double-nut ball screw pair with bidirectional load-bearing according to claim 1, characterized in that, The first preloading mechanism includes a first stop ring and a first elastic member. The first stop ring is coaxially installed with the first nut. The first elastic member is installed on the nut seat. The telescopic direction of the first elastic member is perpendicular to the axis of the first stop ring. There is a convex structure on the first stop ring, and the first elastic member supports and pushes on the convex structure; The second preloading mechanism includes a second stop ring and a second elastic member. The second stop ring is coaxially installed with the second nut. The second elastic member is installed on the nut seat. The telescopic direction of the second elastic member is perpendicular to the axis of the second stop ring. There is a convex structure on the second stop ring, and the second elastic member supports and pushes on the convex structure.

3. The double-nut ball screw pair with bidirectional load-bearing according to claim 1, characterized in that, The first locking mechanism is a first electromagnetic brake, and the second locking mechanism is a second electromagnetic brake; A first connecting piece fixed to the brake disc of the first electromagnetic brake is installed at the front end of the first nut, and a second connecting piece fixed to the brake disc of the first electromagnetic brake is installed at the rear end of the second nut.

4. The double-nut ball screw pair with bidirectional load-bearing according to claim 2, characterized in that, The first elastic member includes a guide cylinder, an adjusting nut, a disc spring group, a slider and a steel ball; The root of the guide cylinder is installed on the adjusting nut. The adjusting nut is threadedly connected to the stud. The stud is detachably connected to the nut seat; The disc spring group and the slider are installed in the guide cylinder. The root of the disc spring group is connected to the root of the guide cylinder. The slider is connected to the front end of the disc spring group. There is a conical card slot at the front end of the slider. The steel ball is located in the conical card slot. The front side of the steel ball or a part of the front side of the slider is outside the guide cylinder, and the steel ball supports and pushes on the convex structure of the first stop ring.

5. The double-nut ball screw pair with bidirectional load-bearing according to claim 1, characterized in that, The first nut has an axle shoulder structure. Thrust cylindrical roller bearings are arranged on both sides of the axle shoulder structure, and needle bearings are arranged on the circumferential side of the axle shoulder structure.

6. The operation control method of the double-nut ball screw pair with bidirectional load-bearing according to any one of claims 1 - 5, characterized in that, Including the following steps: Before the lead screw starts to run, control the first locking mechanism to lock the first nut so that the first nut cannot rotate, and control the second locking mechanism to lock the second nut so that the second nut cannot rotate; Before the lead screw runs and switches from uniform speed to deceleration, control the first locking mechanism to lock the first nut so that the first nut cannot rotate, and control the second locking mechanism to lock the second nut so that the second nut cannot rotate.

7. The operation control method according to claim 6, characterized in that, Including the following steps: After the lead screw starts to run, if the first nut is the working nut, control the second locking mechanism to open so that the second nut can rotate; After the lead screw starts to run, if the second nut is the working nut, control the first locking mechanism to open so that the first nut can rotate.

8. The pre-tightening force adjustment method of the double-nut ball screw pair with bidirectional load-bearing according to any one of claims 1 - 5, characterized in that, Including the following steps: In the initial state, rotate the first nut and the second nut so that the first nut and the second nut reach the initial preloading state; Then, install the first elastic member and the second elastic member, and adjust the jacking forces of the first elastic member and the second elastic member so that the first nut and the second nut rotate by a certain angle in opposite rotation directions respectively to achieve pre-tightening force adjustment.

9. The pre-tightening force adjustment method according to claim 8, characterized in that, After installing the first elastic member and the second elastic member, only adjust the jacking force of the first elastic member or the second elastic member so that the first nut and the second nut rotate by a certain angle in opposite rotation directions respectively to achieve pre-tightening force adjustment.

10. A single-direction load-bearing nut ball screw pair, characterized in that, Comprising: A lead screw, a first nut, a first pre-tightening mechanism and a nut seat; The first nut is sleeved and installed on the lead screw, the nut seat supports the outer side of the first nut, and the nut seat limits the first nut axially; One end of the nut seat is provided with a first locking mechanism; The first locking mechanism is used to control the freedom degree of the rotation direction of the first nut; The first pre-tightening mechanism is used to jack the first nut in the pre-tightening rotation direction.

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