TWI773509B - Outer circulating ball screw - Google Patents

Abstract

An outer circulating ball screw includes a screw shaft, a nut mounted on the screw shaft and defined with at least one through hole having an opening end edge passing through the nut, a return assembly connected to the nut and defined with a return slot having a return section and a continuation section, one end of the return section is communication with the through hole and has a connecting end edge abutting against the opening end edge, the other end of the return section is connected to the continuation section, the return section rotates around a reference point, an outer wall of the return section is curved and the reference point is the center, the outer wall of the return section is one rotation radius from the reference point, the rotation radius is greater than or equal to 1.2 times that of the diameter of a ball, and is less than or equal to 1.5 times that of the diameter of the ball.

Description

External circulation ball screw

The present invention relates to a ball screw, in particular to an external circulation type ball screw.

In order to respond to today's automotive electronics and consumer electronics products, the ball screw is developed towards miniaturization. However, in the design of the existing internal circulation reflow sheet, there is generally a height difference between the nut and the reflow sheet, so the diameter of the ball In smaller cases, there will be a noticeable stutter.

The existing tangential external circulation ball screw, please refer to FIG. 1 , including a nut 70 , a return cover 80 combined with the nut 70 , and a plurality of balls 90 that can circulate between the nut 70 and the return cover 80 . , the nut 70 has two through holes 71, the extension direction of the through holes 71 is defined as a moving direction Z, the return upper cover 80 has a rotation channel 81, the rotation channel 81 communicates with the through holes 71, so that the ball 90 To achieve the effect of backflow, the rotary channel 81 and the through hole 71 are tangentially connected, and the rotary channel 81 has a rotary section 811 and an extension section 812 connected to each other, because the rotary channel 81 and the through hole 71 are tangentially connected The swivel space of the swivel section 811 is large, so when the ball 90 enters the swivel section 811 from the through hole 71, the ball 90 will inertialy hit the opposite upper edge of the wall 811A of the swivel section 811, so that the ball 90 hits and rotates After the wall surface 811A of the segment 811, the component force of the reaction force along the moving direction Z is large, so that the front ball 90 and the rear ball 90 are pushed, resulting in the disadvantages of large ball squeezing and impact force.

The new model provides an external circulation type ball screw, the main purpose of which is to provide a miniature ball screw that can make the ball flow smoothly and avoid the problem of ball squeezing.

In order to achieve the foregoing purpose, the external circulation type ball screw of the present invention includes:

a screw shaft;

a nut sleeved on the screw shaft, a ball passage is formed between the nut and the screw shaft, the nut has at least one through hole communicating with the ball passage, and the through hole has an open end edge;

A plurality of balls are arranged in the ball channel in a cyclic rolling manner, and the diameter of the ball is defined as a ball diameter;

A return element is combined with the nut, the return element has a rotating groove, the rotating groove communicates with the through hole, the rotating groove has a rotating section connected with the through hole, and the rotating section is connected with one end of the through hole There is a connecting end edge, the connecting end edge abuts the opening end edge, the opening end edge and the connecting end edge are connected non-tangentially, the turning section revolves around a reference point, and the turning section corresponds to an outer The wall surface, the outer wall surface is arc-shaped and takes the reference point as the center of the circle, the outer wall surface of the turning section is separated from the reference point by a radius of gyration, the length of the radius of gyration is greater than or equal to 1.2 times the diameter of the bead, and the radius of gyration is equal to or greater than 1.2 times the diameter of the bead. The length is less than or equal to 1.5 times the diameter of the bead.

As can be seen from the foregoing, the present invention is mainly based on defining that the length of the radius of gyration is greater than or equal to 1.2 times the diameter of the bead, the length of the radius of gyration is less than or equal to 1.5 times the diameter of the bead, and the opening edge is connected to the joint. The end edge connection is non-tangential connection, which can effectively reduce the problem of ball squeezing caused by the unsmooth flow of the ball.

The present invention provides an external circulation type ball screw. In one embodiment, please refer to FIGS. 2-4 , comprising: a screw shaft 10 extending along an axis L, the outer peripheral surface of the screw shaft 10 has an outer surface The thread groove 11, the axis L defines an axial direction X; a nut 20 is sleeved on the screw shaft 10, the nut 20 has a through hole 20A for the screw shaft 10 to pass through, and the nut 20 has a relative An inner side wall 21 and an outer side wall 22, the outer side wall 22 is flat, the inner side wall 21 faces the through hole 20A, the inner side wall 21 has an inner thread groove 211, the inner thread groove 211 corresponds to the outer thread groove 11 , a ball channel T1 is formed between the inner thread groove 211 and the outer thread groove 11 , the nut 20 has two first screw holes 23 and two through holes 24 , the two first screw holes 23 and the two through holes 24 Passing through the outer side wall 22, the ball channel T1 communicates with the two through holes 24, the two through holes 24 passing through the outer side wall 22 is an opening edge 241, and the extension direction of the through hole 24 is a vertical direction Y; The balls 30 are arranged in the ball channel T1 in a cyclic rolling manner, and the diameter of the balls 30 is defined as a ball diameter BD. In a specific embodiment, the ball diameter BD is between 1.0 mm and 0.4 mm; a return element 40 is combined with On the outer side wall 22 of the nut 20 , the return element 40 has a bearing surface 40A facing the outer side wall 22 , the bearing surface 40A is flat, and the bearing surface 40A has a revolving groove 41 . The groove 41 and the two through holes 24 together form a return path T2, and the return path T2 communicates with the ball channel T1. The rotating groove 41 includes a rotating section 411, a continuation section 412 and a lead-out section 413 connected in sequence. The swivel section 411 communicates with one of the through holes 24 , the lead-out section 413 communicates with the other through hole 24 , and an end of the swivel section 411 connected to the through hole 24 has a connecting end edge 411A, the connecting end edge 411A abuts against At the opening edge 241 , the other end of the turning section 411 is connected to the continuation section 412 , and the extending direction of the turning section 411 includes the components of the axial direction X and the vertical direction Y, so that an outer wall surface corresponding to the turning section 411 is 411B is arc-shaped, the revolving section 411 revolves around a reference point A, the outer wall surface 411B takes the reference point A as the center of the circle, the outer wall surface 411B and the reference point A are separated from the reference point A by a radius of gyration R, and the length of the radius of gyration R is greater than or equal to 1.2 times the bead diameter BD, the length of the radius of gyration R is less than or equal to 1.5 times the bead diameter BD;

The joint of the opening edge 241 and the connecting edge 411A is non-tangentially connected, so that the return path T2 is a non-tangential path.

Thereby, since the connecting end edge 411A of the turning section 411 of the turning groove 41 and the opening end edge 241 of the through hole 24 are connected non-tangentially, compared with the conventional tangential connecting design, the same turning radius R is In this case, the rotating space of the rotating section 411 of the present invention is small, and the position of the ball 30 hitting the outer wall surface 411B of the rotating section 411 is closer to the connecting end edge 411A, so that the reaction force of the ball 30 hitting the outer wall surface 411B is along the axial direction. The component force of X is relatively large, so the balls 30 in the front are less likely to be pushed by the balls 30 in the rear when they enter the continuation section 412 along the revolving section 411 , so the impact force is small, thereby improving the smoothness of the return flow.

The return element 40 further has two second screw holes 43 , the positions of the two second screw holes 43 correspond to the positions of the two first screw holes 23 respectively, and two locking members 50 respectively pass through the first screw holes 23 and the second screw hole 43 to lock the return element 40 to the nut 20 .

Preferably, the return element 40 further has two extension parts 42 , the extension parts 42 extend from the bearing surface 40A, one of the extension parts 42 is adjacent to the turning section 411 , and the other extension part 42 is adjacent to the bearing surface 40A. In the lead-out section 413 , the extending portions 42 extend into the through holes 24 respectively.

The above is the configuration description of the main components of each embodiment of the present invention, and the description of the effect of the present invention is as follows:

The impact force on the rotating channel 81 when the ball 90 passes through the conventional reflow upper cover 80 is simulated by computer. Please refer to FIGS. 5A to 5C . The conventional rotating channel 81 and the through hole 71 are tangentially connected, and the diameter of the ball is 0.6mm. In the case of , the impact force caused by the balls 90 passing through the rotary channel 81, the broken lines in the coordinates represent the impact force generated by the balls 90 at different time points in the rotary channel 81, the horizontal axis in the diagram represents time, and the unit of time is Second (S), the vertical axis represents the impact force, the unit of the impact force is Newton (N). When the radius of gyration is 0.7mm, please refer to Figure 5A, the average impact force of the ball 90 is 13N, and the maximum impact force of the ball 90 When the radius of gyration is 0.8mm, please refer to Figure 5B, the average impact force of the ball 90 is 1.5N, the maximum impact force of the ball 90 is 3.09N, and the radius of gyration is 0.9mm, please refer to Figure 5C, the ball 90 The average impact force of the ball 90 is 3.7N, and the maximum impact force of the ball 90 is 6.47N.

The impact force on the revolving groove 41 when the ball 30 passes through the recirculation element 40 of the present invention is simulated by computer. Please refer to FIGS. 5D to 5F. The through hole 24 and the revolving groove 41 are non-tangentially connected to the present invention, and the diameter of the ball is BD. In the case of 0.6mm, the impact force caused by the ball 30 passing through the rotary groove 41, each broken line in the coordinates represents the impact force generated by each ball 30 in the rotary groove 41 at different time points, the horizontal axis in the diagram represents time, and the vertical axis represents time. The axis represents the impact force. When the radius of gyration R is 0.8mm, please refer to Figure 5D, the average impact force of the ball 30 is 0.29N, the maximum impact force of the ball 30 is 0.75N, and the radius of gyration R is 0.85mm, please refer to the figure 5E, the average impact force of the ball 30 is 0.26N, the maximum impact force of the ball 30 is 0.89N, and the radius of gyration R is 0.9mm, please refer to Figure 5F, the average impact force of the ball 30 is 0.38N, and the maximum impact force of the ball 30 is 0.38N. The force is 0.66N.

Please also refer to FIG. 5G , in the case where the through hole 24 and the turning groove 41 are non-tangentially connected and the bead diameter BD is 0.6 mm, however, when the turning radius R is 1.0 mm, the turning radius cannot be satisfied. Under the condition that the length of R is less than or equal to 1.5 times the diameter of the ball BD, the ball 30 will be stuck in the test result and cannot flow back smoothly.

To sum up, it can be seen from the above that even though the turning radius R is both 0.8 mm, the average impact force of the ball 30 is only 0.29 N when the through hole 24 and the turning groove 41 are connected in a non-tangential manner, and the turning channel 81 and the through hole 71 are tangential. The average impact force of the balls 90 is increased to 1.5N when the formulas are connected. In addition, although the radius of gyration R is both 0.9mm, when the through hole 24 and the turning groove 41 are connected non-tangentially, the average impact force of the balls 30 is The impact force is only 0.38N, and the average impact force of the ball 90 is increased to 3.7N when the rotary channel 81 and the through hole 71 are connected tangentially.

As can be seen from the foregoing, the present invention is mainly based on defining that the length of the radius of gyration R is greater than or equal to 1.2 times the diameter of the bead BD, the length of the radius of gyration R is less than or equal to 1.5 times the diameter of the bead BD, and the open end The connection between the edge 241 and the connection end edge 411A is non-tangential connection, which can effectively reduce the problem of ball squeezing caused by the unsmooth flow of the balls 30 .

"Knowledge Technology"

70: Nut

71: Through hole

80: Reflow upper cover

81: Rotary channel

811: Rotation section

811A: Wall

812: Extension

90: Ball

Z: moving direction

"This Creation"

10: Screw shaft

11: External thread groove

20: Nut

20A: Perforated

21: Inner side wall

211: Internal thread groove

22: Outer side wall

23: The first screw hole

24: Through hole

241: Open end edge

30: Ball

40: Reflow element

40A: bearing surface

41: Rotary groove

411: Rotation section

411A: Connecting edge

411B: Outer wall

412: Continuation

413: export segment

42: Extensions

43: Second screw hole

50: lock device

L: axis

T1: Ball channel

T2: Return path

A: Reference point

R: radius of gyration

BD: Bead Diameter

X: Axial

Y: vertical direction

Figure 1 shows a conventional ball screw in which the rotary channel and the through hole are tangentially connected.

Figure 2 is an exploded view of the external circulation ball screw of this creation.

Figure 3 is a schematic top view of the external circulation ball screw of the present invention.

FIG. 4 is a schematic diagram of the non-tangential connection of the through hole and the rotary groove.

5A is a graph showing the impact force data under the condition that the gyration radius is 0.7 mm in the case where the conventional turning channel and the through hole are tangentially connected, wherein each broken line in the coordinates represents each ball at different times The impact force generated by the point, the horizontal axis represents time, the unit of time is seconds (S), the vertical axis represents the impact force, and the unit of impact force is Newton (N).

FIG. 5B is a graph of impact force data presented under the condition that the gyration radius is 0.8 mm when the conventional turning channel and the through hole are connected tangentially.

FIG. 5C is a graph of impact force data presented under the condition that the gyration radius is 0.9 mm when the conventional turning channel and the through hole are tangentially connected.

FIG. 5D is a graph of the impact force data presented under the condition that the through hole and the turning groove of the present invention are connected in a non-tangential manner, and the turning radius is 0.8 mm.

FIG. 5E is a graph showing the impact force data under the condition that the through hole and the turning groove of the present invention are connected in a non-tangential manner, and the turning radius is 0.85 mm.

FIG. 5F is a graph of the impact force data presented under the condition that the through hole and the turning groove of the present invention are connected non-tangentially, and the turning radius is 0.9 mm.

Fig. 5G is a graph of the impact force data presented under the condition that the through hole and the turning groove of the present invention are connected in a non-tangential manner, and the turning radius is 1.0 mm.

20: Nut

20A: Perforated

21: Inner side wall

211: Internal thread groove

22: Outer side wall

24: Through hole

241: Open end edge

30: Ball

40: Reflow element

40A: bearing surface

41: Rotary groove

411: Rotation section

411A: Connecting edge

411B: Outer wall

12: Continuation paragraph 4

T1: Ball channel

T2: Return path

A: Reference point

R: radius of gyration

BD: Bead Diameter

X: Axial

Y: vertical direction

Claims (5)

An external circulation type ball screw, comprising: a screw shaft; A nut is sleeved on the screw shaft, there is a ball channel between the nut and the screw shaft, the nut There is at least one through hole communicating with the ball passage, and the through hole has an open end edge; A plurality of balls are arranged in the ball channel in a cyclic rolling manner, and the diameter of the ball is defined as one ball path; A return element is combined with the nut, the return element has a rotating groove, the rotating groove communicates with the through hole, the rotating groove has a rotating section connected with the through hole, and the rotating section is connected with one end of the through hole There is a connecting end edge, the connecting end edge abuts the opening end edge, the opening end edge and the connecting end edge are connected non-tangentially, the turning section revolves around a reference point, and the turning section corresponds to an outer The wall surface, the outer wall surface is arc-shaped and centered on the reference point, the outer wall surface is a radius of gyration away from the reference point, the length of the radius of gyration is greater than or equal to 1.2 times the diameter of the bead, and the length of the radius of gyration is less than or is equal to 1.5 times the diameter of the bead. The external circulation type ball screw according to claim 1, wherein the diameter of the ball is between 1.0 mm and 0.4 mm. The external recirculating ball screw according to claim 1, wherein the rotary groove further comprises a continuation section and a lead-out section, the other end of the rotary section connected to the through hole is connected to the continuation section, and the continuation section is connected to the lead-out section The number of the through holes is two, and the lead-out section communicates with another through hole. The external circulation type ball screw according to claim 1, wherein the nut has a through hole for the screw shaft to pass through, the screw shaft has an external thread groove, and the nut has an opposite inner side wall and an outer side wall , the inner side wall faces the through hole, the inner side wall has an inner thread groove, the inner thread groove corresponds to the outer thread groove, the ball channel is formed between the inner thread groove and the outer thread groove, and the return element is combined with the In the outer side wall of the nut, the opening edge is where the through hole penetrates through the outer side wall. The external circulation type ball screw according to claim 1, wherein the nut has two first screw holes, the return element has two second screw holes, and the positions of the second screw holes are respectively the same as those of the first screw holes. The positions of the holes correspond to each other, and there are also two locking pieces respectively passing through the first screw holes and the second screw holes.

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