Retainer type non-circulating ball screw

Abstract

The utility model relates to a ball screw technical field especially a kind of non-circulation ball screw of retainer type.The first spiral raceway is equipped on the inner hole wall of screw nut;Second spiral raceway is equipped on the outer peripheral wall of screw shaft;Retainer is sleeved on screw shaft, and it is contained in the space that first spiral raceway and second spiral raceway jointly enclose;Steel ball is installed in the installation groove of retainer correspondingly;Retainer includes the retainer of helical line type structure and multiple keepers distributed along the retainer and several installation grooves for steel ball embedding, adjacent installation groove is separated by keeper, and it is integrally formed structure between retainer and keeper, and retainer is more stable when operating;Equidistant retainer connection, stable operation, no ball risk of falling;First bottom groove cooperates with retainer, and the axial location of retainer is carried out, prevent its twist when operating prevent retainer fracture;Second bottom groove cooperates with first bottom groove, prevent retainer from coming off screw shaft when operating, with very high axial rigidity.

Description

Technical Field

[0001] This utility model relates to the field of ball screw technology, and in particular to a retainer-type non-circulating ball screw. Background Technology

[0002] With the advancement and development of robots, there is a stronger demand in China for inverse ball screw products that are small in size, strong in structure, and highly flexible. This is especially true in the field of robotics, where there is an even greater demand for small or even micro ball screws, which are an important component of robot joints.

[0003] Existing conventional non-recirculating ball screws are either all-steel ball screws or ball screws without a retainer. However, in pure steel ball non-recirculating ball screws, the ball spacing is variable during operation, leading to problems with load-bearing capacity and operational instability.

[0004] Existing unlimited retainer ball screws are divided into two types: split type and chain type retainer. The disadvantage of the split type retainer is that it is not suitable for non-circulating ball screws. The disadvantage of the latter is that during operation, the chain type retainer lacks axial limit, and the rotation of the steel ball causes the chain retainer to twist, which can lead to the problem of the retaining chain breaking in the retaining chain ball screw. Utility Model Content

[0005] The technical problem to be solved by this utility model is: in order to solve the problems existing in the prior art in the background art, to provide a retainer-type non-circulating ball screw with a compact structure, the retaining block and the retainer are connected as one unit, stable operation, and the ability to prevent torsion and breakage during operation.

[0006] The technical solution adopted by this utility model to solve its technical problem is: a retainer-type non-circulating ball screw, comprising... The nut has a first spiral raceway on its inner wall, which acts as a driven element to convert the thrust transmitted from the steel ball into its own linear motion. The lead screw shaft has a second helical raceway on its outer peripheral wall that cooperates with the first helical raceway. As the driving element, it rotates and converts the torque into a thrust on the steel ball through the second helical raceway. The retainer is sleeved on the lead screw shaft and housed in the space enclosed by the first and second helical raceways. This completed space directly bears the working load and evenly transmits the load to the steel balls. Multiple steel balls are installed in the mounting slots of the retainer to convert sliding friction into rolling friction and withstand the axial force from the lead screw shaft and lead nut; The retainer includes a spiral-shaped cage, multiple retaining blocks distributed along the cage, and multiple mounting slots for inserting steel balls. Adjacent mounting slots are separated by retaining blocks. The spiral-shaped cage ensures the strength and shape of the entire retainer. The mounting slots provide an independent movement space for the steel balls, isolating them and preventing them from colliding and rubbing against each other during movement, thus reducing wear and noise. The cage and retaining blocks are integrally formed, improving the structural strength of the retainer and making its operation more stable. Furthermore, the helical pitch of the retainer is the same as that of the first and second helical raceways, ensuring that all steel balls are guided to perform synchronized planetary rotation.

[0007] Furthermore, the mounting slots are spaced evenly, resulting in a compact structure, more stable operation, and no risk of the ball falling off.

[0008] Furthermore, the bottom of the raceway groove of the first helical raceway of the nut is provided with a first bottom groove arranged along the helical direction; The bottom of the raceway groove of the second helical raceway of the lead screw shaft is provided with a second bottom groove arranged along the helical direction; The inner radial ring of the retainer is engaged and positioned in the second bottom groove, and the outer radial ring of the retainer is engaged and positioned in the first bottom groove. The first and second bottom grooves provide precise radial positioning for the retainer, preventing radial movement and vibration of the retainer during operation and significantly improving the rigidity of the system.

[0009] Furthermore, the width of the first and second bottom grooves is 0.09 to 0.11 times the diameter of the steel ball, and the depth of the first and second bottom grooves is 15 to 18 mm. The precise definition of the width and depth of the first and second bottom grooves ensures that there is an optimal gap between the retainer and the bottom groove. This gap must be small enough to ensure guiding accuracy and rigidity, and large enough to allow lubricating oil to enter and form an oil film, while smoothly discharging wear debris.

[0010] Furthermore, the bottom of the first and second bottom grooves is a concave arc-shaped surface, and the surfaces of the radial inner and radial outer rings of the retaining block in the retainer are both convex arc-shaped surfaces that cooperate with the concave arc-shaped surfaces. The complementary arc-shaped surfaces between the retainer and the first and second bottom grooves transform sliding friction into well-lubricated surface contact or rolling friction, which greatly reduces frictional resistance and wear, improves transmission efficiency, reduces heat generation, and extends service life.

[0011] Furthermore, the first and second bottom grooves are through grooves that run along a spiral direction.

[0012] Furthermore, the thickness of the retainer in the retainer is less than or equal to the width of the first bottom groove in the lead screw nut and the second bottom groove in the lead screw shaft.

[0013] Furthermore, the radius of curvature of the inner arc of the retaining block is greater than the radius of the steel ball. This ensures approximately point contact with the steel ball, while a gap is left on the outer side to facilitate lubrication, primarily to reduce friction.

[0014] Furthermore, the axial length of the retainer is less than or equal to half the axial length of the lead screw shaft; The maximum relative travel between the lead screw nut and the lead screw shaft is less than or equal to half the axial length of the lead screw shaft; The retainer is radially constrained within the lead screw nut and moves synchronously with the lead screw shaft in the axial direction.

[0015] The beneficial effects of this utility model are: 1. Compared with traditional unconnected retainers, the spiral retainers of this utility model are interconnected as one unit, which improves the structural strength of the retainer and makes the retainer more stable during operation. It is highly practical in non-circulating lead screws. 2. The use of equally spaced cages for connection results in a more compact structure and more stable operation compared to non-circulating pure steel ball types, eliminating the risk of ball drop. 3. The spiral raceway of the nut has a first bottom groove, which cooperates with the retainer to axially limit the retainer during operation, prevent it from twisting and prevent the retainer from breaking. The lead screw shaft has a second bottom groove on its helical raceway, which cooperates with the first bottom groove to prevent the retainer from dislodging from the lead screw shaft during operation; thus resulting in extremely high axial rigidity. 4. The complementary arc-shaped surfaces between the retainer and the first and second bottom grooves transform sliding friction into well-lubricated surface contact or rolling friction, which greatly reduces frictional resistance and wear, improves transmission efficiency, reduces heat generation, and extends service life. 5. Keep the radius of curvature of the inner arc of the block larger than the radius of the steel ball, so that it is approximately in point contact with the steel ball, and leave a gap on the outer side to facilitate lubrication, mainly to reduce friction. Attached Figure Description

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0017] Figure 1 This is a schematic diagram of the structure of this utility model; Figure 2 This is a schematic diagram of the structure of the retainer of this utility model; Figure 3 This is a schematic diagram of the structure of the retainer after the steel ball is assembled. Figure 4 This is a schematic diagram of the structure of the wire mother of this utility model; Figure 5 This is a structural schematic diagram of part A of this utility model; Figure 6This is a schematic diagram of the structure of the lead screw shaft of this utility model; Figure 7 This is a structural schematic diagram of part B of this utility model; Figure 8 This is a schematic diagram of the structure of the fit between the steel ball and the cage in this utility model; In the diagram: 1. Nut, 11. First spiral raceway, 12. First bottom groove. 2. Lead screw shaft, 21. Second helical raceway, 22. Second bottom groove, 3. Retainer; 31. Mounting slot; 32. Retainer bracket; 33. Retaining block. 4. Steel ball. Detailed Implementation

[0018] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the present invention, and therefore only show the components relevant to the present invention.

[0019] A non-circulating ball screw is a special type of ball screw in which the internal steel balls 4 do not circulate through an external circulator or return pipe, but instead undergo infinite continuous planetary rotation within the load raceway between the nut 1 and the screw shaft 2.

[0020] Imagine it as a closed circular track where all athletes (4 steel balls) run on the same track without exiting or re-entering.

[0021] like Figures 1-8 The retainer-type non-recirculating ball screw shown is particularly suitable for applications with limited installation space but requiring high-rigidity linear motion, including... The nut 1 has a first spiral raceway 11 on its inner wall; The lead screw shaft 2 has a second helical raceway 21 on its outer peripheral wall that cooperates with the first helical raceway 11. The first helical raceway 11 and the second helical raceway 21 bear the working load. The retainer 3 is sleeved on the lead screw shaft 2 and housed in the space enclosed by the first helical raceway 11 and the second helical raceway 21. The helical pitch of the retainer 3 is the same as that of the first helical raceway 11 and the second helical raceway 21. Multiple steel balls 4 are installed in the mounting groove 31 of the retainer 3. By rolling between two raceways, the rotational motion of the lead screw shaft 2 is efficiently converted into the linear motion of the lead nut 1. Its rolling friction coefficient is much lower than that of sliding friction, thereby improving the transmission efficiency. The retainer 3 includes a spiral-shaped retainer 32, multiple retaining blocks 33 distributed along the retainer 32, and multiple mounting slots 31 for inserting steel balls 4. The spiral-shaped retainer 32 provides the geometric skeleton and mechanical strength of the entire retainer 3, and determines the movement trajectory of the steel balls 4. The spiral-shaped retainer 32 is a rigid component. The mounting slot 31 accommodates the steel ball 4 and provides radial constraint for it. The mounting slots 31 are evenly spaced to maintain the spacing and prevent the steel ball from falling off or moving excessively. Adjacent mounting slots 31 are separated by retaining blocks 33. The retainer 32 and retaining blocks 33 are integrally formed structures with high structural strength and stability, avoiding loosening and abnormal noise caused by split mechanisms. The precise relative position allows for accurate control of the spacing of the steel ball 4. During operation, the retainer 3 is more stable and more practical.

[0022] The helical cage 32 has a simple and compact design. The cage 3 moves with the steel ball 4, and moves forward when the steel ball 4 moves forward. The lead screw shaft 2 is relatively short, and the cage 3 occupies half of the lead screw shaft 2. The axial length of the cage 3 is less than or equal to half the axial length of the lead screw shaft 2. The stroke of the lead screw shaft 2 and the lead screw nut 1 is relatively short, only half the length of the lead screw shaft 2. The maximum relative stroke between the lead screw nut 1 and the lead screw shaft 2 is less than or equal to half the axial length of the lead screw shaft 2. At the same time, the cage 3 is radially constrained within the lead screw nut 1, and the cage 3 moves synchronously with the lead screw shaft 2 in the axial direction.

[0023] In addition, such as Figure 1 As shown, the thickness of the retainer 32 in the retainer 3 is slightly less than or equal to the width of the first bottom groove 12 in the lead screw nut 1 and the second bottom groove 22 in the lead screw shaft 2, so that the retainer 32 rolls in the first bottom groove 12 and the second bottom groove 22.

[0024] like Figure 8 As shown, the radius of curvature of the inner side of the block 33 is slightly larger than the radius of the steel ball 4, and it is in approximately point contact with the steel ball 4. A gap is left on the outer side to facilitate lubrication, reduce friction, and form radial clearance, allowing it to rotate freely.

[0025] like Figures 4-7 As shown, the bottom of the raceway groove of the first helical raceway 11 of the nut 1 is provided with a first bottom groove 12 arranged along the helical direction, which mainly restricts the axial displacement and torsion of the retainer 3 during operation. The bottom of the raceway groove of the second helical raceway 21 of the lead screw shaft 2 is provided with a second bottom groove 22 arranged along the helical direction, which cooperates with the first bottom groove 12 on the lead screw nut 1 to prevent the retainer 3 from coming off the lead screw shaft 2 during operation. The first bottom groove 12 and the second bottom groove 22 are through grooves that run along the spiral direction. The radial inner ring of the retainer 3 is inserted into and positioned in the second bottom groove 22, and the radial outer ring of the retainer 3 is inserted into and positioned in the first bottom groove 12. The first bottom groove 12 and the second bottom groove 22 limit the axial direction of the retainer 3 to prevent the retainer 3 from undergoing torsional deformation that affects the movement due to the rotation of the steel ball 4 during the movement.

[0026] like Figure 5 and Figure 7 As shown, the width of the first bottom groove 12 and the second bottom groove 22 is 0.09 to 0.11 times the diameter of the steel ball 4, and the depth of the first bottom groove 12 and the second bottom groove 22 is 15 to 18 mm. This not only axially limits the retainer 3, but also allows the retainer 3 to move axially along the bottom groove, making the movement of the retainer 3 smooth and without jamming.

[0027] like Figure 5 and Figure 7 As shown, the bottom of the grooves of the first bottom groove 12 and the second bottom groove 22 are concave arc surfaces. The surfaces of the radial inner ring and radial outer ring of the retainer 33 are convex arc surfaces that cooperate with the concave arc surfaces, which are surface contact or rolling friction, reducing frictional resistance and improving transmission efficiency. In addition, the edges of the radial inner ring and radial outer ring of the retainer 32 are chamfered.

[0028] Installation process: All steel balls 4 are installed on the mounting groove 31 to complete the assembly of the retainer 3. Then the retainer 3 is installed on the second helical raceway 21 of the screw shaft 2, and the radial inner ring of the retainer 32 is inserted into the second bottom groove 22. Then, it is matched with the nut 1, and the radial outer ring of the retainer 32 is inserted into the first bottom groove 12 to assemble a non-circulating ball screw.

[0029] In summary, the nut 1 and the screw shaft 2 provide a platform for inputting / outputting power, the steel ball 4 serves as a high-efficiency transmission medium, the integrally formed cage 32 serves as a skeleton, the steel ball 4 performs a smooth, quiet, and shock-free planetary motion, and the first bottom groove 12 and the second bottom groove 22 provide precise positioning and smooth guidance for the cage 3, forming a high-rigidity, high-precision, low-noise, long-service-life, and compact non-circulating ball screw.

[0030] Based on the above-described preferred embodiments of this utility model, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the technical concept of this utility model. The technical scope of this utility model is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A retainer-type non-recirculating ball screw, characterized in that: include The nut (1) has a first spiral raceway (11) on its inner wall. The lead screw shaft (2) has a second spiral raceway (21) on its outer peripheral wall that cooperates with the first spiral raceway (11). The retainer (3) is sleeved on the lead screw shaft (2) and housed in the space enclosed by the first helical raceway (11) and the second helical raceway (21); Multiple steel balls (4) are installed in the mounting slot (31) of the retainer (3); The retainer (3) includes a spiral-shaped retainer (32) and multiple retaining blocks (33) distributed along the retainer (32) and multiple mounting slots (31) for inserting steel balls (4). Adjacent mounting slots (31) are separated by retaining blocks (33), and the retainer (32) and retaining blocks (33) are integrally formed.

2. A retainer-type non-recirculating ball screw according to claim 1, characterized in that: The helical pitch of the retainer (3) is the same as that of the first helical raceway (11) and the second helical raceway (21).

3. A retainer-type non-recirculating ball screw according to claim 1, characterized in that: The mounting slots (31) are spaced at equal intervals.

4. A retainer-type non-recirculating ball screw according to claim 1, characterized in that: The bottom of the first spiral raceway (11) of the nut (1) is provided with a first bottom groove (12) arranged along the spiral direction. The bottom of the raceway groove of the second helical raceway (21) of the lead screw shaft (2) is provided with a second bottom groove (22) arranged along the helical direction. The radial inner ring of the retainer (3) is inserted into and positioned in the second bottom groove (22), and the radial outer ring of the retainer (3) is inserted into and positioned in the first bottom groove (12).

5. A retainer-type non-recirculating ball screw according to claim 4, characterized in that: The width of the first bottom groove (12) and the second bottom groove (22) is 0.09 to 0.11 times the diameter of the steel ball (4), and the depth of the first bottom groove (12) and the second bottom groove (22) is 15 to 18 mm.

6. A retainer-type non-recirculating ball screw according to claim 4, characterized in that: The bottom of the first bottom groove (12) and the second bottom groove (22) are concave arc surfaces, and the surfaces of the radial inner ring and radial outer ring of the retainer (3) are convex arc surfaces that cooperate with the concave arc surfaces.

7. A retainer-type non-recirculating ball screw according to claim 4, characterized in that: The first bottom groove (12) and the second bottom groove (22) are through grooves that run along the spiral direction.

8. A retainer-type non-recirculating ball screw according to claim 4, characterized in that: The thickness of the retainer (32) in the retainer (3) is less than or equal to the width of the first bottom groove (12) in the screw nut (1) and the second bottom groove (22) in the screw shaft (2).

9. A retainer-type non-recirculating ball screw according to claim 1, characterized in that: The radius of curvature of the inner side of the retaining block (33) is greater than the radius of the steel ball (4).

10. A retainer-type non-recirculating ball screw according to claim 1, characterized in that: The axial length of the retainer (3) is less than or equal to half the axial length of the lead screw shaft (2); The maximum relative motion stroke between the lead screw nut (1) and the lead screw shaft (2) is less than or equal to half the axial length of the lead screw shaft (2); The retainer (3) is radially constrained within the lead screw (1) and moves synchronously with the lead screw shaft (2) in the axial direction.

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