JPH0527408U - Ball screw - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a ball screw having a structure that has excellent operating characteristics, enables highly accurate operation, has a large load capacity and high rigidity, and has a quiet operating sound. [Structure] A strip retainer 5 is arranged so as to be capable of circulating movement over the entire length of a circulation path 3 between a screw shaft 1 and a ball nut 2, and balls 4 can be rotated in a large number of ball pockets of the strip retainer 5. Hold each. The balls 4 are prevented from coming into contact with each other by the parts between the ball pockets to ensure high operating characteristics due to smooth rolling, and there is no contact noise between the balls 4, and a ball screw of the total ball type is used. It is possible to secure the same number of balls 4 arranged.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a ball screw, and more particularly to a ball screw provided with a retainer for holding a large number of balls circulated between a screw shaft and a ball nut.

[0002]

[Prior Art]

 Conventional ball screws are of the so-called total ball type in which balls of equal diameter are closely and continuously arranged in the circulation path formed by the screw grooves provided in the screw shaft and ball nut. , And a so-called spacer ball type in which spacer balls each having a smaller diameter than the balls are alternately arranged between balls having a regular diameter for supporting a load in the circulation path. As.

[0003]

[Problems to be solved by the device]

 However, any of these structures has the following problems, and improvements thereof have been demanded. In the ball screw of the total ball type of (1), the balls a, a, ... Are closely arranged as shown in FIG. 7, so that the balls rotate in opposite directions (sliding contact). As a result, mutual rolling is hindered, resulting in a decrease in operating efficiency, fluctuations in the rotation torque, large variations in the rotation torque, and poor operating characteristics. For this reason, smooth screw movement is not possible and it is not suitable for operating parts that require high precision.

In the ball screw of the spacer ball type of (2), since the balls come into rolling contact with each other due to the action of the spacer balls, the operating characteristics are superior to the total ball type, but Is almost halved, and the load capacity is small and the rigidity is poor. In both (3) and (3), since adjacent balls collide with each other, the rotation noise (contact noise) during operation is large, and it is particularly noticeable during high-speed feed operation by high-speed rotation.

The present invention has been made in view of the above-mentioned conventional problems, and is capable of operating with high accuracy and excellent operating characteristics, large load capacity and high rigidity, and operating noise. The purpose is to provide a ball screw with a quiet structure.

[0006]

[Means for Solving the Problems]

 To achieve the above object, in the ball screw of the present invention, a flexible strip retainer is provided in the ball circulation path so as to be able to circulate over the entire length of the circulation path, and a large number of ball pockets are provided in the band retainer. It is characterized in that the balls are provided at predetermined intervals over the entire length, and the balls are rotatably held in these ball pockets.

More specifically, a pair of guide grooves for guiding both side edge portions of the strip retainer are provided in the inner diameter portion of the ball circulation pipe provided in the ball nut over the entire length. Both ends of are connected to an annular space formed between the outer diameter surface of the screw shaft and the inner diameter surface of the ball nut. In addition, notches that allow torsional deformation of the retainer are provided at predetermined intervals on both side edges of the strip retainer. These notches are provided between adjacent ball pockets at the same pitch as the pitch of the ball pockets.

[0008]

[Action]

 By holding each ball circulating in the circulation path in the ball pocket of the strip retainer, a large number of balls can be arranged. The balls are prevented from contacting each other by the parts between the ball pockets, ensuring high motion characteristics due to smooth rolling, and there is no contact noise between the balls.

The strip retainer is guided by the pair of guide grooves of the ball circulation pipe provided in the ball nut and the annular space between the screw shaft and the ball nut, and smoothly circulates in the circulation path.

[0010]

【Example】

 An embodiment according to the present invention will be described below with reference to the drawings. 1 to 4 show a ball screw according to the present invention, in which a plurality of balls 4, 4, ... Are circulated in a circulation path 3 formed between a screw shaft 1 and a ball nut 2. These balls 4, 4, ... Are rotatably held by a strip retainer 5.

The circulation path 3 is attached to an outer diameter portion of the ball nut 2 and a spiral cylindrical load load zone formed between an outer diameter portion of the screw shaft 1 and an inner diameter portion of the ball nut 2. And a circulation path formed by the ball circulation pipe 6 thus formed.

That is, the spiral groove 1b having an arcuate cross section is provided on the outer diameter surface 1a of the screw shaft 1, and the spiral groove 2b having an arcuate cross section is formed on the inner diameter surface 2a of the ball nut 2 in the spiral groove 1b. Correspondingly provided, these load grooves are formed by these spiral grooves 1b, 2b, and both ends of this load region are connected to the circulation path at both ends.

The belt-shaped retainer 5 is provided for smooth rolling movement of each ball 4 in the circulation path 3, and is provided so as to be circulated and movable over the entire length of the circulation path 3 (see FIG. 5). . The strip retainer 5 has elastic flexibility and is formed of a flexible material such as a synthetic resin sheet material.

The strip-shaped retainer 5 has a width dimension larger than the inner diameter dimension of the circulation path 3 (corresponding to the outer diameter dimension of the ball 4) and, as shown in FIG. 6, a large number of ball pockets 7, 7. , ... are provided at regular intervals along the entire length in the longitudinal direction. The balls 4, 4, ... Are rotatably housed and held in the ball pockets 7, 7 ,. The adjacent balls 4, 4 are located in the space between the ball pockets 7, 7. It is prevented from directly contacting by a certain isolation portion 5a.

Further, a large number of notches 5c, 5c, ... To allow the torsional deformation of the retainer 5 are provided at both side edge portions 5b, 5b of the strip retainer 5 at predetermined intervals. These notches 5c, 5c, ... Are arc-shaped, and are provided at the same pitch as the pitch of the ball pockets 7 at the center position in the longitudinal direction between the adjacent ball pockets 7, 7. . The arrangement pitch of the ball pockets 7 is set so as to hold as many balls 4, 4, ... As possible while taking into consideration the use of the ball screw, the outer diameter of the balls 4, and the like.

Further, the circulation path 3 is provided with guide portions for guiding the both side edge portions 5b, 5b of the strip retainer 5 over the entire length. That is, as shown in FIG. 3, a pair of guide grooves 8 and 8 for guiding both side edge portions 5b and 5b of the strip retainer 5 are provided on the inner diameter surface 6a of the ball circulation pipe 6 over the entire length, and Both ends of these guide grooves 6a, 6a are connected to an annular space 9 (see FIG. 4) formed between the outer diameter surface 1a of the screw shaft 1 and the inner diameter surface 2a of the ball nut 2. As a result, the strip retainer 5 is circulated in the circulation path 3 while being guided by the guide portions 8, 8 and 9.

When the screw shaft 1 and the ball nut 2 rotate relative to each other in the ball screw configured as described above, the balls 1 and 2 are circulated in the circulation path 3 and a large number of balls are circulated. By the action of 4, 4, ..., Relative spiral motion (screw motion) is performed, and the desired axial motion is performed.

In this case, the balls 4 circulatingly moving in the circulation path 3 are rotatably held in the ball pockets 7 of the strip retainer 5 so that the adjacent balls 4 and 4 are brought into contact with each other by the isolation portion 5a. Since all the balls 4, 4, ... Roll smoothly, a high operating characteristic of the ball screw is secured, and no contact noise between the balls 4, 4 is generated.

The present invention is not limited to the above-described embodiment, and various design changes can be made. For example, in the illustrated example, the shape of the notches 5c, 5c, ... For allowing the torsional deformation of the strip retainer 5 is an arc shape, but it can be deformed to another shape within the range where stress concentration does not occur. is there.

[0020]

[Effect of the device]

 As described above in detail, according to the present invention, various excellent effects as described below can be obtained.

(1) In the ball circulation path, a flexible strip retainer is provided so as to be able to circulate over the entire length of the circulation path, and a large number of ball pockets are provided over the entire length of the strip retainer over a predetermined length. Since the balls are rotatably held in the ball pockets provided at intervals, the operation characteristics are excellent and highly accurate operation is possible.

That is, since the balls that circulate in the circulation path are prevented from contacting each other by the ball pocket portions, adjacent balls do not hinder each other from rolling. High operating efficiency is obtained, and fluctuations in rotational torque are unlikely to occur, and there is almost no rotational torque unevenness, resulting in excellent operating characteristics. Therefore, it is suitable for moving parts that can move smoothly and requires high precision, for example, parts that require precise positioning such as semiconductor transfer devices.

(2) Since the balls are rotated and held in the ball pockets of the strip retainer, by setting the longitudinal dimension of the space between the ball pockets to be small, adjacent balls can be placed close to each other. It is also possible to arrange the balls, and it is possible to secure the same number of balls as the conventional total ball type. As a result, a large load capacity can be secured and a ball screw with excellent rigidity can be provided.

(3) Further, since adjacent balls do not collide with each other, contact noise between the balls does not occur during operation, and high quietness can be secured, especially at high speed due to high speed rotation. It can be optimally used for feeding.

(4) A pair of guide grooves for guiding both side edges of the strip retainer are provided over the entire length in the inner diameter portion of the ball circulation pipe provided in the ball nut, and both ends of the pair of guide grooves are screwed. Since it is connected to the annular space formed between the outer diameter surface of the shaft and the inner diameter surface of the ball nut, the strip retainer is guided by these guide grooves and the annular space to smoothly move in the circulation path. It can be circulated and moved, and it does not cause significant twisting and has a long life.

(5) A large number of notches that allow torsional deformation of the retainer are provided at predetermined intervals on both side edges of the strip retainer, and notches that allow torsional deformation of the retainer are provided at predetermined intervals. Therefore, it is possible to effectively prevent the occurrence of an unreasonable twisting phenomenon in the strip retainer, and also in this respect, a long life can be secured.

[Brief description of drawings]

FIG. 1 is a front view showing a ball screw according to an embodiment of the present invention.

FIG. 2 is a sectional view of the ball screw taken along line II-II in FIG.

3 is a sectional view of the ball screw taken along line III-III in FIG.

4 is a sectional view of the ball screw taken along line IV-IV in FIG.

FIG. 5 is a perspective view showing a state in which a ball-shaped retainer, which is a main part of the ball screw, and a ball circulation path are arranged, and a screw shaft is shown by an imaginary line.

FIG. 6 is an enlarged perspective view showing a part of a strip retainer of the ball screw and a ball.

FIG. 7 is a side view showing a rolling state of adjacent balls in a conventional total ball type ball screw.

[Explanation of symbols]

1 screw shaft 1a screw shaft outer diameter surface 1b screw shaft spiral groove 2 ball nut 2a ball nut inner diameter surface 2b ball nut spiral groove 3 circulation path 4 ball 5 band retainer 5a band retainer isolation part (ball pocket 5b Strips on both sides of the retainer 5c Cutouts on the strip retainer 6 Ball circulation pipe 7 Ball pocket 8 Ball circulation pipe guide groove 9 Annular space

Claims (3)

[Scope of utility model registration request] 1. A ball screw having a large number of balls circulated between a screw shaft and a ball nut so that a flexible strip retainer circulates in the circulation path of the balls over the entire length of the circulation path. A ball screw, which is movably provided, has a large number of ball pockets provided at predetermined intervals over the entire length thereof, and the balls are rotatably held in the ball pockets. 2. A pair of guide grooves for guiding both side edge portions of the strip retainer are provided over an entire length in an inner diameter portion of a ball circulation pipe provided in the ball nut, and both ends of the pair of guide grooves are The ball screw according to claim 1, wherein the ball screw is continuous with an annular space formed between an outer diameter surface of the screw shaft and an inner diameter surface of the ball nut. 3. A plurality of notches that allow the torsional deformation of the retainer are provided at predetermined intervals on both side edges of the strip retainer, and the notches are provided at positions between the ball pockets adjacent to each other. The ball screw according to claim 1, wherein the ball screw is provided at the same pitch as the arrangement pitch.