A roller screw pair with constant tooth line position

Abstract

The present invention discloses a roller screw pair with a constant tooth line position, comprising a center screw, a wire roller, a bearing seat, a spacer sleeve and bolts. The wire roller is a ring-shaped wire roller, and the bearing seat is a step-screw bearing seat. The ring-shaped wire roller, the step-screw bearing seat and the spacer sleeve are bolted together by bolts to form an inner cavity raceway to be screwed into the center screw. After the center screw is screwed into the inner cavity raceway, a roller screw pair with a constant tooth line position between the ring-shaped wire roller and the center screw is formed. The position of the inner cavity raceway is constant in this roller screw pair, and the tooth line position of each ring-shaped wire roller and the center screw is relatively constant in this roller screw pair. In this way, the inner cavity raceway of the center screw will not be changed by the asynchronous rotation of each wire roller, thereby ensuring stable and smooth operation of the mechanism.

Description

Technical Field

[0001] The invention belongs to the technical field of mechanical transmission components, and in particular relates to a roller screw pair which converts rotary motion into linear motion and has a constant tooth line position. Background Art

[0002] The existing planetary roller screw mechanisms currently have the problem of the position of the tooth line moving during operation. For this reason, the existing planetary roller screw mechanisms have paid two high prices: first, when the roller screw mechanism is operating, the internal wire rollers must strictly rotate synchronously at all times, and the entire mechanism will be stuck if there is a slight deviation; second, when the roller screw mechanism is operating, the rolling of the wire rollers is not pure, and there is sliding, which will cause stealing and leakage, resulting in distorted counting when the mechanism converts rotational motion into linear motion, that is, when the existing roller screw is driven by a servo motor, the encoder data is not completely consistent with the actual roller screw operation data. Summary of the invention

[0003] In view of the above problems, the present invention provides a roller screw pair with a constant tooth line position. During operation, the tooth line position of the wire roller and the center screw does not move with the rotation of the wire roller and the center screw. Its purpose is to solve the problem that the entire mechanism is stuck when the wire rollers rotate asynchronously during operation of the existing roller screw mechanism, thereby ensuring stable and smooth operation of the mechanism. Its purpose is also to solve the problem that the wire rollers of the existing roller screw mechanism are not pure in rolling and slip during operation, and the slip will cause the phenomenon of stolen rotation and missed rotation, resulting in distorted counting when the mechanism converts rotational motion into linear motion, that is, the encoder data is not completely consistent with the actual roller screw operation data when the servo motor drives the roller screw.

[0004] The technical solution of the present invention:

[0005] A roller screw pair with a constant tooth line position, comprising a center screw, a wire roller, a bearing seat, a spacer sleeve, and a bolt, characterized in that: the middle of the wire roller is surrounded by a zero-lift angle annular pattern with the same tooth shape as the center screw, the wire roller is an annular wire roller, and both ends of the annular wire roller are bearing platforms integrally connected to the middle of the annular wire roller; the bearing seat is a step-lift bearing seat, and a center screw hole is provided in the center. The step-lift bearing seat has an outer side surface and an inner side surface, and the inner side surface of the step-lift bearing seat is provided with a zero-lift angle annular pattern surrounding the center screw hole to follow the center screw The rod has a multi-stage rotating step surface with equal spacing in the direction of the rotating angle, and a spacer sleeve mounting surface is arranged around the outer periphery of the multi-stage rotating step surface, each step surface of the multi-stage rotating step surface is provided with a bearing groove for inserting and connecting with a matching annular wire roller bearing seat, and the spacer sleeve mounting surface is provided with a bolt hole for matching bolt bolting; the annular wire roller, the step rotating bearing seat and the spacer sleeve are bolted together by bolts to form an inner cavity raceway to be screwed into the center screw, and after the center screw is screwed into the inner cavity raceway, a roller screw pair with a constant tooth line position between the annular wire roller and the center screw is formed.

[0006] The central screw rod is a triangular thread, which can be a single-start thread or a multi-start thread.

[0007] There are two step-lift bearing seats, and the paired installation requires that the highest surface of the step surface of one step-lift bearing seat is paired with the lowest surface of the step surface of the other step-lift bearing seat.

[0008] There are four annular wire rollers, which have the same pitch and axis as the central screw rod, and the spacing angle between the annular wire rollers is 90°.

[0009] The annular wire roller is made of elastic material, and the outer diameter of the annular pattern in the middle of the annular wire roller gradually increases from both ends to the middle to form a drum-shaped annular wire roller, which is pre-tightened and meshed with the central screw thread and rolls in a counter-rotating manner.

[0010] The bearing platform is a cylinder with a frustum-shaped top, which is directly inserted into the bearing groove through lubricant and is slidably connected or rollingly connected with the bearing groove.

[0011] The step-lift bearing seat is in the shape of a truncated cone, and the multi-step lifting step surface outside the central screw hole of the step-lift bearing seat is in the shape of four steps with equal spacing, and is provided with four bearing grooves.

[0012] The four steps of the step-lift bearing seat are 0.5mm apart step by step along the lifting angle direction of the central screw rod, and the central screw rod is a single-threaded rod with a pitch of 2mm.

[0013] The spacer sleeve mounting surface of the step-lift bearing seat is an annular plane, and bolt holes are arranged at equal intervals on the periphery of the middle of adjacent bearing grooves.

[0014] There are four spacer sleeves, which are sleeved outside the bolts. The outer ring diameter of the spacer sleeves is larger than the bolt hole diameter. The axial length of the spacer sleeves ensures that the annular thread roller has only rotational clearance but no axial movement clearance in the bearing groove.

[0015] Beneficial effects of the present invention:

[0016] The invention has reasonable structural design, is simple and easy to process, has low cost, is stable in use and easy to maintain, and mainly has the following advantages:

[0017] 1. The wire roller is a ring-shaped wire roller. The ring-shaped wire roller, the step-lift bearing seat, and the spacer sleeve are bolted together to form an inner cavity raceway to be screwed into the center screw. The ring-shaped wire roller is constrained by the bearing grooves on the inner side of the two step-lift bearing seats and can only rotate, not planetary revolution, and the ring-shaped rotation angle surrounding the middle of the ring-shaped wire roller is zero. The self-rotation does not produce the lifting of the ring pattern, so the position of the inner cavity raceway is constant in this roller screw pair. The position of the tooth line between each ring-shaped wire roller and the center screw is relatively constant in this roller screw pair. It does not move with the rotation of the annular wire roller, and the position of the tooth line formed by the inner cavity raceway screwed into the center screw is also constant. This is a technical effect that the existing roller screw mechanism has not achieved. That is to say, when the various annular wire rollers rotate asynchronously, the position of the tooth line between the annular wire roller and the center screw can still be guaranteed to be constant. In this way, the inner cavity raceway of the center screw will not change due to the asynchronous rotation of the various wire rollers, the inner cavity raceway of the center screw will not change, and the center screw will not be stuck, ensuring the stable and smooth operation of the mechanism;

[0018] 2. The tooth line position formed by the annular wire roller and the center screw is constant. Even if there are gaps and friction between them, it will not cause the roller screw pair with a constant tooth line position to rotate or leak, and there will be no counting distortion when the rotational motion is converted into linear motion. That is, the encoder data of the roller screw pair with a constant tooth line position driven by a servo motor is consistent with the actual operation data;

[0019] 3. The wire roller is a drum-shaped annular wire roller. The outer diameter of the annular pattern in the middle gradually increases from both ends to the middle. The annular wire roller is made of elastic material, which plays a radial pre-tightening role to ensure efficient rolling friction between the annular wire roller and the center screw rod;

[0020] 4. The bearing tables at both ends of the annular rollers are inserted into the bearing grooves on the step-lift bearing seat and locked by bolts. The sliding or rolling connection between the bearing table and the bearing seat can be selected according to the actual use accuracy, load and other requirements;

[0021] 5. Insert the bolt into the bolt hole and tighten it. Connect the annular wire roller, the step-lift bearing seat, and the spacer sleeve to form the inner cavity raceway to be screwed into the center screw. After the center screw is screwed into the inner cavity raceway, a roller screw pair with a constant tooth line position between the annular wire roller and the center screw is formed, making disassembly and assembly extremely quick and convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the structure of the present invention.

[0023] Figure 2 It is an exploded view of the structural schematic diagram of the present invention.

[0024] Figure 3 This is a state diagram of the present invention when the center screw rod is not screwed in.

[0025] Figure 4 It is a front view of the schematic diagram of the wire roller structure of the present invention.

[0026] Figure 5 It is a three-dimensional diagram of the bearing seat structure schematic diagram of the present invention.

[0027] Figure 6 It is a top view of the bearing seat structure schematic diagram of the present invention.

[0028] Among them: 1 center screw, 2 annular wire roller, 3 step-lift bearing seat, 4 spacer sleeve, 5 bolt, 6 bearing platform, 7 center screw hole, 8 bearing groove, 9 bolt hole, 10 outer side surface, 11 inner side surface, 12 bolt cap, 13 drum annular pattern, 14 spacer sleeve installation surface. DETAILED DESCRIPTION

[0029] like Figures 1 to 6 As shown, the present invention provides a roller screw pair with a constant tooth line position, including a center screw 1, a wire roller, a bearing seat, a spacer sleeve 4, and a bolt 5. The middle part of the wire roller is surrounded by a zero-lift angle ring pattern with the same tooth shape as the center screw. The wire roller is a ring-shaped wire roller 2, and both ends of the ring-shaped wire roller 2 are bearing seats 6 integrally connected to the middle part of the ring-shaped wire roller 2; the bearing seat is a step-lift bearing seat 3, and a center screw hole 7 is provided in the center. The step-lift bearing seat 3 has an outer side surface 10 and an inner side surface 11. The inner side surface 11 of the step-lift bearing seat 3 is provided with a threaded portion surrounding the center screw hole 7 to follow the center The screw rod 1 has a multi-step lifting step surface with equal spacing in the direction of the lifting angle, and a spacer sleeve mounting surface 14 is arranged around the outer periphery of the multi-step lifting step surface, and each step surface of the multi-step lifting step surface is provided with a bearing groove 8 for inserting and connecting the bearing platform 6 of the matching annular wire roller 2, and a bolt hole 9 for bolting with the matching bolt 5 is arranged on the spacer sleeve mounting surface 14; the annular wire roller 2, the step lifting bearing seat 3, and the spacer sleeve 4 are bolted by bolts 5 to form an inner cavity raceway to be screwed into the center screw rod 1, and after the center screw rod 1 is screwed into the inner cavity raceway, a roller screw pair with a constant tooth line position between the annular wire roller 2 and the center screw rod 1 is formed.

[0030] The center screw 1 is a triangular thread, which can be a single-start thread or a multi-start thread. When the center screw 1 is a single-start thread, the step-lifting surface of the step-lifting bearing seat 3 is a group; when the center screw 1 is a multi-start thread, the step-lifting surfaces of the step-lifting bearing seat 3 are correspondingly provided with the same number of groups, and the adjacent height difference of each group of step-lifting surfaces is the quotient of the lead of the center screw 1 and the number of step surfaces in each group, and the height difference of the first and last step surfaces of each group of step surfaces is the difference between the lead of the center screw 1 and the height difference of the adjacent step surfaces.

[0031] The outer side surface 10 of the stepped rotation bearing seat 3 can be a plane, or can be designed into various shapes such as a raised cylinder according to actual use requirements.

[0032] There are two stepped lifting bearing seats 3 , and the paired installation requires that the highest surface of the stepped surface of one stepped lifting bearing seat 3 is paired with the lowest surface of the stepped surface of another stepped lifting bearing seat 3 .

[0033] The number of the annular wire rollers 2 is at least three, and they have the same pitch and axis as the central screw rod 1 .

[0034] Preferably, the number of the annular wire rollers 2 is four, which have the same pitch and axis as the central screw rod 1, and the spacing angle between the annular wire rollers 2 is 90°.

[0035] The annular wire roller 2 is made of elastic material. The outer diameter of the annular pattern in the middle of the annular wire roller 2 gradually increases from both ends to the middle to form a drum-shaped annular wire roller, which is pre-tightened and meshed with the center screw 1 for rolling and counter-rotation. The annular pattern in the middle of the drum-shaped annular wire roller is slightly bulging by a few ten-thousandths to a few percent. The annular wire roller 2, the step-lift bearing seat 3, and the spacer sleeve 4 are bolted together by bolts 5 to form an inner cavity raceway to be screwed into the center screw 1. The middle part of the inner cavity raceway is slightly tightened by a few ten-thousandths to a few percent. When the center screw 1 is screwed in, due to elastic deformation, the drum-shaped annular wire roller 2 is close to the center screw 1 surface and is deformed into a straight shape due to the meshing pressure. Its two sides also produce elastic changes and become more bulging, thereby playing a radial pre-tightening role, ensuring efficient rolling friction between the annular wire roller and the center screw for meshing and counter-rotation.

[0036] The bearing stand 6 is a cylindrical body with a frustum-shaped top, and is directly inserted into the bearing groove 8 through lubricant to be slidably connected or rollingly connected to the bearing groove 8.

[0037] The bearing groove 8 is a sliding bearing groove, which is a cylindrical blind hole that matches the bearing stand.

[0038] A rolling bearing is also provided in the bearing groove 8. The rolling bearing is fixedly inserted into the axial hole or directly inserted into the bearing platform 6 through a lubricant. The bearing platform 6 is rollingly connected to the bearing groove 8. The rolling bearings are axial, radial, and axial-radial composite.

[0039] The lubricant is one of a solid lubricant or a liquid lubricant, such as graphite, grease or oil.

[0040] like Figure 5 As shown, the step-lift bearing seat 3 is in the shape of a truncated cone, and the multi-step lifting step surface outside the central screw hole 7 of the step-lift bearing seat 3 is in the shape of four steps with equal spacing, and is provided with four bearing grooves 8.

[0041] The four steps of the step-lift bearing seat 3 are 0.5mm apart step by step along the lifting angle direction of the center screw 1. The center screw 1 is a single-head threaded rod with a thread diameter of 16.00mm, a thread middle diameter of 14.70mm, and a pitch of 2mm. The center of the drum-type annular wire roller 2 has an annular diameter of 10.20mm and an annular middle diameter of 8.90mm. The center of the drum-type annular wire roller 2 gradually shrinks toward both ends. The annular diameters at both ends are 10.00mm and the annular middle diameters are 8.70mm. The drum-type annular wire roller 2 is a triangular annular wire with an annular spacing of 2mm. Figure 4 As shown, if the reference surface is set as surface A, then surfaces A, B, C, and D represent four-level step surfaces respectively, and surfaces B, C, and D are 0.5 mm, 1.0 mm, and 1.5 mm higher than surface A respectively.

[0042] The spacer sleeve mounting surface 14 of the step-lift bearing seat 3 is an annular plane, and bolt holes 9 are arranged at equal intervals on the periphery of the middle part of adjacent bearing grooves 8.

[0043] In the present invention, Figure 1 , Figure 2 , Figure 3 As shown, there are four spacer sleeves 4, which are sleeved on the outside of the bolts 5. The outer ring diameter of the spacer sleeves 4 is larger than the diameter of the bolt holes 5. The axial length of the spacer sleeves 4 ensures that the annular wire roller 2 has only rotational clearance in the bearing groove 8 but no axial movement clearance.

[0044] The core of the roller screw pair provided by the present invention lies in that the annular wire roller 2, the step-lift bearing seat 3, and the spacer sleeve 4 are bolted together by bolts 5 to form an inner cavity raceway to be screwed into the center screw 1. The position of the inner cavity raceway is constant in this roller screw pair and does not move with the rolling of the annular wire roller 2. The position of the tooth line formed by the inner cavity raceway with a constant position being screwed into the center screw 1 is also constant. This is a technical effect that the existing roller screws on the market have not achieved.

[0045] When using assembly, Figure 3 As shown, the annular roller 2 can be inserted into the bearing groove 8, and then the spacer sleeve 4 is sleeved, and the bolt 5 is locked through the bolt hole 9 with the bolt cap 12 to form an inner cavity raceway to be screwed into the center screw 1. Figure 1 As shown, finally, you only need to pass the center screw 1 through the center screw hole 7 of the step-lift bearing seat 3 and screw it into 2. However, during installation, you need to pay extra attention to the corresponding relationship between the step surfaces of the step-lift bearing seat 3. The corresponding relationship adopts reverse correspondence, that is, the A surface corresponds to the D surface and the B surface corresponds to the C surface. During use, it has the following advantages:

[0046] 1. The wire roller is a ring-shaped wire roller. The ring-shaped wire roller, the step-lift bearing seat, and the spacer sleeve are bolted together to form an inner cavity raceway to be screwed into the center screw. The ring-shaped wire roller is constrained by the bearing grooves on the inner side of the two step-lift bearing seats and can only rotate, not planetary revolution, and the ring-shaped rotation angle surrounding the middle of the ring-shaped wire roller is zero. The self-rotation does not produce the lifting of the ring pattern, so the position of the inner cavity raceway is constant in this roller screw pair. The position of the tooth line between each ring-shaped wire roller and the center screw is relatively constant in this roller screw pair. It does not move with the rotation of the annular wire roller, and the position of the tooth line formed by the inner cavity raceway screwed into the center screw is also constant. This is a technical effect that the existing roller screw mechanism has not achieved. That is to say, when the various annular wire rollers rotate asynchronously, the position of the tooth line between the annular wire roller and the center screw can still be guaranteed to be constant. In this way, the inner cavity raceway of the center screw will not change due to the asynchronous rotation of the various wire rollers, the inner cavity raceway of the center screw will not change, and the center screw will not be stuck, ensuring the stable and smooth operation of the mechanism;

[0047] 2. The tooth line position formed by the annular wire roller and the center screw is constant. Even if there are gaps and friction between them, it will not cause the roller screw pair with a constant tooth line position to rotate or leak, and there will be no counting distortion when the rotational motion is converted into linear motion. That is, the encoder data of the roller screw pair with a constant tooth line position driven by a servo motor is consistent with the actual operation data;

[0048] 3. The wire roller is a drum-shaped annular wire roller. The outer diameter of the annular pattern in the middle gradually increases from both ends to the middle. The annular wire roller is made of elastic material, which plays a radial pre-tightening role to ensure efficient rolling friction between the annular wire roller and the center screw rod;

[0049] 4. The bearing tables at both ends of the annular rollers are inserted into the bearing grooves on the step-lift bearing seat and locked by bolts. The sliding or rolling connection between the bearing table and the bearing seat can be selected according to the actual use accuracy, load and other requirements;

[0050] 5. Insert the bolt into the bolt hole and tighten it. Connect the annular wire roller, the step-lift bearing seat, and the spacer sleeve to form the inner cavity raceway to be screwed into the center screw. After the center screw is screwed into the inner cavity raceway, a roller screw pair with a constant tooth line position between the annular wire roller and the center screw is formed, making disassembly and assembly extremely quick and convenient.

[0051] In summary, the present invention achieves the intended purpose, the annular wire roller 2, the step-lift bearing seat 3, and the spacer sleeve 4 are bolted together by bolts 5 to form an inner cavity raceway to be screwed into the center screw 1, and after the center screw 1 is screwed into the inner cavity raceway, a roller screw pair with a constant tooth line position between the annular wire roller 2 and the center screw 1 is formed, and the step-lift bearing seat 3 is divided into multiple steps, and the annular wire roller 2 is designed to be a slightly bulging drum shape, so that the transmission efficiency is higher, the counter-rotation transmission is more stable, the cost is lower, it has a wide range of application space, is of great promotion value, and can bring great economic benefits to enterprises.

[0052] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention, such as using the ring pattern of the step-lift ring-shaped wire roller to replace the equivalent replacement mode of the step-lift bearing seat. Therefore, as long as the roller screw pair with a constant tooth line position belongs to the scope of protection of the present invention, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is limited by the attached claims rather than the above description, and it is intended to include all changes within the meaning and scope of the equivalent elements of the claims.

Claims

1. A roller screw pair with a constant tooth line position, comprising a central screw, a screw roller, a bearing seat, a spacer sleeve, and a bolt, characterized in that: The middle part of the wire roller is surrounded by a zero-lift angle ring pattern with the same tooth shape as the center screw rod, and the wire roller is a ring-shaped wire roller, and both ends of the ring-shaped wire roller are bearing platforms integrally connected to the middle part of the ring-shaped wire roller; the bearing seat is a step-lift bearing seat, and a center screw rod hole is provided in the center. The step-lift bearing seat has an outer side surface and an inner side surface. The inner side surface of the step-lift bearing seat is provided with a multi-stage lifting step surface that surrounds the center screw rod hole and is equidistant along the lifting angle direction of the center screw rod, and a spacer sleeve mounting surface is provided around the outer periphery of the multi-stage lifting step surface, and each step surface of the multi-stage lifting step surface is provided with a bearing groove that is inserted and connected to the ring-shaped wire roller bearing platform, and the spacer sleeve mounting surface is provided with a bolt hole that is bolted with a bolt; the ring-shaped wire roller, the step-lift bearing seat, and the spacer sleeve are bolted to form an inner cavity raceway to be screwed into the center screw rod by bolts, and after the center screw rod is screwed into the inner cavity raceway, a roller screw pair with a constant tooth line position between the ring-shaped wire roller and the center screw rod is formed; The annular wire roller is constrained by the bearing grooves on the inner side of the two-step rotation bearing seat and can only rotate on its own, not on the planetary revolution; The position of the tooth line between each annular wire roller and the center screw is relatively constant in this roller screw pair and does not move with the rotation of the annular wire roller; The annular wire roller is made of elastic material, and the outer diameter of the annular pattern in the middle of the annular wire roller gradually increases from both ends to the middle to form a drum-shaped annular wire roller, which is pre-tightened and meshed with the central screw thread and rolls in a counter-rotating manner; When the center screw is screwed in, the drum-shaped annular wire roller is close to the center screw surface due to elastic deformation and is deformed into a straight shape under the meshing pressure. Its two sides also produce elastic deformation and become more bulging, thus playing a radial pre-tightening role to ensure efficient rolling friction between the annular wire roller and the center screw.

2. A roller screw pair with a constant tooth line position as claimed in claim 1, characterized in that: The central screw rod is a triangular thread, which is a single-start thread or a multi-start thread.

3. A roller screw pair with a constant tooth line position as claimed in claim 1, characterized in that: There are two step-lift bearing seats, and the paired installation requires that the highest surface of the step surface of one step-lift bearing seat is paired with the lowest surface of the step surface of the other step-lift bearing seat.

4. A roller screw pair with a constant tooth line position as claimed in claim 1, characterized in that: There are four annular wire rollers, which have the same pitch and axis as the central screw rod, and the spacing angle between the annular wire rollers is 90°.

5. A roller screw pair with a constant tooth line position as claimed in claim 1, characterized in that: The bearing platform is a cylinder with a frustum-shaped top, which is directly inserted into the bearing groove through lubricant and is slidably connected or rollingly connected with the bearing groove.

6. A roller screw pair with a constant tooth line position as claimed in claim 1, characterized in that: The step-lift bearing seat is in the shape of a truncated cone, and the multi-step lifting step surface outside the central screw hole of the step-lift bearing seat is in the shape of four steps with equal spacing, and is provided with four bearing grooves.

7. A roller screw pair with a constant tooth line position as claimed in claim 1, characterized in that: The four steps of the step-lift bearing seat are 0.5mm apart step by step along the lifting angle direction of the central screw rod, and the central screw rod is a single-threaded rod with a pitch of 2mm.

8. A roller screw pair with a constant tooth line position as claimed in claim 1, characterized in that: The spacer sleeve mounting surface of the step-lift bearing seat is an annular plane, and bolt holes are arranged at equal intervals on the periphery of the middle of adjacent bearing grooves.

9. A roller screw pair with a constant tooth line position as claimed in claim 1, characterized in that: There are four spacer sleeves, which are sleeved outside the bolts. The outer ring diameter of the spacer sleeves is larger than the bolt hole diameter. The axial length of the spacer sleeves ensures that the annular thread roller has only rotational clearance but no axial movement clearance in the bearing groove.

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