CN-224214648-U - Axial pre-tightening device for retainer of roller screw

CN224214648UCN 224214648 UCN224214648 UCN 224214648UCN-224214648-U

Abstract

The utility model provides a retainer axial pre-tightening device of a roller screw, which comprises a screw, a nut, a roller set, a retainer set and a pre-tightening set. The roller set has a plurality of first rollers and second rollers which are staggered, and the periphery of each roller is provided with annular teeth which are meshed with a thread structure of the screw rod and an annular groove section in the nut. The retainer sets are arranged at the two ends of the roller sets, and the first and second gaps are formed by utilizing the axial length difference of the two ends of the first and second rollers. The pre-tightening piece group axially penetrates through the retaining piece group and applies adjustable fastening force to enable the retaining piece group to clamp the roller group, and further the first roller and the second roller are respectively applied with opposite directions and adjustable axial pre-compression force to form a staggered bidirectional pre-compression effect. The design can eliminate back clearance, ensure pure rolling contact, improve transmission stability and service life, and avoid using a snap ring, thereby saving space and avoiding friction problem.

Inventors

LIN JUNHAN
ZENG YONGZHI
CHEN BAIYUN
HUANG SHUNYONG

Assignees

富世达股份有限公司

Dates

Publication Date: 20260508
Application Date: 20250604

Claims (6)

1. A cage axial pretensioning device for a roller screw, comprising: the peripheral surface of the screw is provided with a thread structure; the nut is provided with an inner hole sleeved with the screw rod, and at least one annular groove section is arranged on the inner side of the inner hole; the roller set is arranged between the screw and the nut and is provided with a plurality of first rollers and a plurality of second rollers which are arranged in a staggered way, and the peripheral surface of each first roller and each second roller is provided with a plurality of annular teeth which are respectively meshed with the thread structure and the annular groove section; The nut comprises a nut, a roller set, a retaining member group, a pre-tightening member group and a screw bolt, wherein the roller set is arranged in the nut and is provided with a first retaining member and a second retaining member which are arranged at two ends of the roller set, the first retaining member is connected with one ends of a plurality of first rollers and a plurality of second rollers, the second retaining member is connected with the other ends of the plurality of first rollers and the plurality of second rollers, a first gap is arranged between one ends of the plurality of first rollers and the first retaining member, a second gap is arranged between one ends of the plurality of second rollers and the second retaining member, the plurality of first gaps and the second gaps are arranged at opposite ends of the roller set in a staggered manner, the pre-tightening member group is arranged between the first retaining member and the second retaining member, an adjustable tightening force is generated to enable the first retaining member and the second retaining member to be close to each other, the roller set is clamped, the first gap and the second gap are matched with the second gap in a staggered manner, and axial pre-tightening force which is opposite in direction and can regulate and roll quantity is applied to the plurality of first rollers and the second rollers respectively, so that the set forms a staggered axial pre-tightening force and maintains the pre-tightening screw bolt and a pure pre-tightening screw bolt and a pre-tightening nut.
2. The axial pre-tightening device for the retainer of the roller screw according to claim 1, wherein the pre-tightening member set comprises at least two pre-tightening screws respectively arranged between the first retainer and the second retainer and parallel to the first rollers and the second rollers, each pre-tightening screw is provided with a threaded end and a head end, the threaded end is in threaded connection with one of the first retainer and the second retainer, and the head end is abutted against the other of the first retainer and the second retainer.
3. The roller screw cage axial pretensioning device of claim 2, wherein: The first retainer is provided with a plurality of first positioning grooves and at least one first matching part, the plurality of first positioning grooves are used for accommodating one ends of the plurality of first rollers and the plurality of second rollers, and the at least one first matching part is used for accommodating the threaded end of the pre-tightening screw and is provided with an internal thread matched with the threaded end; The second retainer is provided with a plurality of second positioning grooves and at least one second matching part, the second positioning grooves are used for accommodating the other ends of the first rollers and the second rollers, and the at least one second matching part corresponds to the head end of the pre-tightening screw.
4. A roller screw cage axial pretensioning device according to claim 3, characterized in that: The axial length of one end of the first roller is smaller than that of the other end of the first roller and does not contact the bottom of the first positioning groove to form the first gap, and The axial length of one end of the second roller accommodated in the second positioning groove is smaller than the length of the other end of the second roller, and the second roller does not contact with the bottom of the second positioning groove, so that the second gap is formed.
5. The axial pre-tightening device for the retainer of the roller screw according to claim 2, wherein the first retainer is provided with a plurality of first positioning grooves and at least one first matching portion, the second retainer is provided with a plurality of second positioning grooves and at least one second matching portion, the threaded end of one pre-tightening screw penetrates through the second matching portion of the second retainer and is in threaded connection with the first matching portion of the first retainer, the head end of the other pre-tightening screw abuts against the outer side of the second matching portion of the second retainer, the threaded end of the other pre-tightening screw penetrates through the first matching portion of the first retainer and is in threaded connection with the second matching portion of the second retainer, and the head end of the other pre-tightening screw abuts against the outer side of the first matching portion of the first retainer.
6. The axial pretensioning device for roller screw holder according to claim 5, wherein the first retainer and the second retainer are respectively provided with an internal thread at the first engaging portion and the second engaging portion corresponding to the screw-coupling end to engage with the screw-coupling end.

Description

Axial pre-tightening device for retainer of roller screw Technical Field The utility model relates to a transmission assembly, in particular to a retainer axial pre-tightening device of a roller screw, which can generate adjustable axial pre-compression force on a roller so as to improve rolling stability. Background The planetary roller screw is synchronously and rollingly engaged between the screw and the nut by virtue of a plurality of rollers, so that the rotary motion is efficiently converted into linear motion, and the planetary roller screw has high load capacity, high rigidity and high positioning precision and is widely applied to systems such as a machine tool, a servo actuator, space flight control and the like. As shown in fig. 1A, the conventional planetary roller screw transmission device includes a screw 11, a nut 12, a plurality of rollers 13, and a cage set 14. The screw 11 is provided with an external thread structure, the nut 12 is provided with an inner hole 120 for accommodating the roller 13, and a ring-shaped tooth structure 12t is arranged on the inner circumference and is in rolling contact with the ring-shaped tooth of the roller 13. The retainer sets 14 are disposed at two ends of the rollers 13 to limit circumferential spacing and angular distribution and maintain positioning. To prevent the retainer set 14 from axially displacing during movement, two embedded grooves 121 are provided in the nut 12 to respectively configure a retaining ring 15 (e.g. a C-shaped buckle or a ring-shaped buckle), and the retaining ring 15 is disposed on the outer side of the retainer set 14 and contacts with the retainer set to fix the axial position and prevent the retainer set from falling out. However, conventional designs still have a number of problems. As shown in fig. 1B and 1C, the geometric fit among the roller 13, the screw 11 and the nut 12 is very precise, however, a small gap G is generated between the roller 13 and the screw 11/nut 12 due to manufacturing tolerance and assembly error, and the actual contact position of the roller 13 deviates from the designed pitch radius position. If the fit clearances G are not compensated effectively, the roller 13 and the nut 12 lack sufficient friction force to generate sliding or idle running, and it is difficult to maintain pure rolling contact, resulting in sliding friction. Thus causing the rollers 13 to experience greater wear and reducing overall structural life. Similarly, the roller 13 and the screw 11 may slide due to insufficient contact, so as to destroy the speed reduction and propulsion effects of the planetary motion, and reduce the linear propulsion efficiency and positioning accuracy. Although the cage set 14 can control the angle and the distance between the rollers 13, it has only a mechanical positioning function, and cannot provide pre-compression compensation or pre-compression direction of the guide rollers, and the problem of sliding offset caused by the gap G cannot be effectively improved. More importantly, the actual contact between the cage set 14 and the retaining ring 15 generates frictional resistance, and when the cage set 14 rotates with the roller 13, the cage set and the retaining ring 15 slide relatively, so that abrasion and resistance are generated, the consistency and fluency of the movement of the roller 13 are affected, and the transmission efficiency is reduced and the precision is deteriorated. In addition, the embedded groove 121 structure required for the retaining ring 15 occupies valuable axial space of the nut 12, which limits miniaturization and compact design of the whole transmission assembly, and limits application situations requiring space minimization or high structural integrity. Therefore, how to effectively improve the contact stability between the roller 13 and the nut 12 and strengthen the rolling engagement between the roller 13 and the screw 11 without increasing the structural complexity and the manufacturing cost, so as to ensure that the screw 11, the roller 13 and the nut 12 maintain stable rolling motion is an important subject to be overcome in the field. Disclosure of utility model The utility model aims to provide an axial pre-tightening device for a retainer of a roller screw, which can effectively solve the technical problems, can compensate a fit clearance generated by machining errors, and respectively apply axial pre-tightening forces with opposite directions and adjustable pre-tightening amount to a first roller and a second roller which are arranged in a staggered way so as to avoid sliding friction between a roller group and a screw/nut, ensure rolling contact and further improve the overall service life. Simultaneously, the back clearance can be effectively eliminated, the transmission stability and the positioning precision are enhanced, the design of fixing the axial position of the retainer by the retaining ring is avoided, the structure is simplified, the axial space