CN110375046B - Ball screw structure - Google Patents

Abstract

The invention provides a ball screw structure, which comprises a screw, a nut, a plurality of balls and a two-piece type return pipe, wherein the screw comprises an external thread groove, the nut is sleeved on the screw and comprises two mounting holes and an internal thread groove, the two mounting holes and the internal thread groove correspond to the external thread groove to form a load channel for the balls to roll, the two-piece type return pipe is arranged on the nut and communicated with the load channel, and the two-piece type return pipe comprises a first combined component and a second combined component; the second combined member is combined with the first combined member and comprises two feet and is used for inserting each mounting hole, each foot comprises a cylindrical body and a cylindrical channel, the cylindrical channel penetrates through the cylindrical body, each ball enters the cylindrical channel, and a bias space is arranged in the cylindrical channel and used for allowing the balls to enter the cylindrical channel along the tangential direction of movement, so that the rolling smoothness of the balls is increased.

Description

Ball screw structure

Technical Field

The present invention relates to a ball screw structure, and more particularly, to a ball screw structure using a two-piece return pipe.

Background

The ball screw comprises a screw, a nut, a reflux pipe and a plurality of balls, the nut is sleeved on the screw and forms a load channel for the balls to pass through with the screw, and the reflux pipe is arranged on the nut and used for guiding the balls, changing the direction of the balls and achieving the purpose of ball circulation. The known return pipe is made of plastic materials, and is manufactured by a plastic extrusion molding process, so that the return pipe is generally divided into two symmetrical half bodies to be molded and manufactured independently and then combined into a complete return pipe in consideration of the problem of difficult demolding.

Under the condition, the shovel-shaped connecting section (commonly called as a nail in the industry) of the foot part of the return pipe is also divided into a left half and a right half, however, when the ball rolls and operates, the ball can impact the shovel-shaped connecting section and then change the rolling direction, so that if the shovel-shaped connecting section is divided into two halves, the shovel-shaped connecting section is easy to damage, and the two half angle bodies are propped apart to generate a section difference or a gap due to the impact of the ball, the rolling smoothness of the ball is influenced, even foreign matter invasion is caused, and the service life of the ball screw is shortened.

In addition, the load channel is spiral, so the balls will roll unsmoothly when entering the return pipe to change direction, which may also cause stress concentration to damage the return pipe.

Therefore, how to effectively improve the structure of the return pipe, increase the structural strength thereof, and improve the combination stability is an objective of the related manufacturers.

Disclosure of Invention

The invention provides a two-piece type return pipe and a ball screw structure, which can increase the rolling smoothness of balls through the same structural configuration in the two-piece type return pipe and the ball screw structure.

According to one aspect of the present invention, a ball screw structure is provided, which includes a screw, a nut, a plurality of balls, and a two-piece return tube. The screw comprises an external thread groove; the nut sleeve is arranged on the screw rod and is provided with an axial direction, the nut comprises two mounting holes and an internal thread groove, the two mounting holes penetrate through a body of the nut, and each mounting hole comprises a bearing end face; the internal thread groove corresponds to the external thread groove to form a load channel, the internal thread groove is communicated with the two mounting holes, and the internal thread groove is respectively connected with the two bearing end faces through two groove edges; the balls roll in the load channel. The two-piece type return pipe is arranged on the screw cap and communicated with the load channel to allow each ball to enter the inside of the two-piece type return pipe, and comprises a first combination component and a second combination component. The first combined component comprises a first pipe body and a first side groove, and the first side groove is concavely arranged on the first pipe body; the second combined component is combined with the first combined component and comprises a second pipe body, a second side groove and two feet, the second pipe body corresponds to the first pipe body, the second side groove is concavely arranged on the second pipe body, and the second side groove and the first side groove are combined to form a ball channel. The two feet are respectively connected with two opposite ends of the second pipe body and used for being inserted into each mounting hole, each foot comprises a columnar body and a cylindrical channel, one end of the columnar body is connected with the second pipe body, the other end of the columnar body comprises a supporting end face which is supported against the supporting end face, the cylindrical channel penetrates through the columnar body to form an inner wall face, each ball is led to the ball channel from the internal thread groove, and the inner wall face is axially far away from the groove edge so as to form an offset space in the cylindrical channel and allow each ball to enter the cylindrical channel along a motion tangential direction.

Therefore, the rolling smoothness of the ball can be increased by enabling the ball to enter the cylindrical channel along the tangential direction of motion through the offset space.

According to the ball screw structure, each ball has a ball diameter value, each cylindrical body has a central axis, each cylindrical passage has a central axis and a passage diameter value, a difference value is equal to the passage diameter value minus the ball diameter value, wherein a connection line of the two central axes intersects with a connection line of the two central axes, and the central axes located at the same foot are closer to the offset space than the central axes and have a distance from the central axes smaller than or equal to the difference value. The aforementioned distance may be less than or equal to 1mm and greater than or equal to 0.05 mm.

According to the above ball screw structure, each of the abutting end surfaces includes a first region and a second region, the first region is adjacent to the offset space, and the second region is far away from the offset space. Each bearing end face comprises a first section and a second section, the first section is used for bearing the first zone, the second section is used for bearing the second zone, and the length of one end edge of the first section is greater than that of one end edge of the second section. Or the first combined component further comprises an outer embedding concave and an inner embedding concave, the outer embedding concave is arranged on the first pipe body, the outer embedding concave is positioned on the outer side of the first side groove and faces the second pipe body, the inner embedding concave is arranged on the first pipe body, and the inner embedding concave is positioned on the inner side of the first side groove and faces the second pipe body; the second combined component can also comprise an outer flange and an inner flange, the outer flange is arranged on the second tube body, the outer flange is positioned on the outer side of the second side groove and corresponds to the outer embedding concave, the outer flange is embedded with the outer embedding concave, the inner flange is arranged on the second tube body, the inner flange is positioned on the inner side of the second side groove and corresponds to the inner embedding concave, and the inner flange is embedded with the inner embedding concave. Or the external fitting recess and the external flange may be connected together by ultrasonic welding, and the internal fitting recess and the internal flange may be connected together by ultrasonic welding.

According to the ball screw structure, the first combination member further includes a hole penetrating through the first tube and located outside the first side groove; the second combined component further comprises a clamping tenon which is convexly arranged on the second pipe body, the clamping tenon is positioned outside the groove on the second side and corresponds to the hole in position, the clamping tenon comprises a protruding section and a convex circle, the protruding section protrudes towards the first pipe body and is provided with a D-shaped cross section, and the convex circle is connected with the protruding section; wherein the tenon passes through the hole, and the convex circle is limited to combine the first pipe body and the second pipe body. Or a cross-section of the hole may be D-shaped.

According to another aspect of the present invention, a ball screw structure is provided, which includes a screw, a nut, a plurality of balls, and a two-piece return tube, wherein the screw includes an external thread groove, the nut is sleeved on the screw and has an axial direction, the nut includes two mounting holes and an internal thread groove, the internal thread groove corresponds to the external thread groove to form a load channel, and the balls roll in the load channel. The two-piece type return pipe is arranged on the screw cap and communicated with the load channel to allow each ball to enter the interior of the two-piece type return pipe, and the two-piece type return pipe comprises a first combination component and a second combination component; the second combined component and the first combined component are combined and comprise two feet which are used for being respectively inserted into each mounting hole, each foot comprises a cylindrical body and a cylindrical channel, the cylindrical channel penetrates through the cylindrical body, each ball enters the cylindrical channel, and an offset space is arranged in each cylindrical channel and used for each ball to enter the cylindrical channel along a motion tangential direction.

According to the ball screw structure, each ball has a ball diameter value, each cylindrical body has a central axis, each cylindrical passage has a central axis and a passage diameter value, a difference value is equal to the passage diameter value minus the ball diameter value, wherein a connection line of the two central axes intersects with a connection line of the two central axes, and the central axes located at the same foot are closer to the offset space than the central axes and have a distance from the central axes smaller than or equal to the difference value.

Drawings

Fig. 1 is a perspective view of a ball screw structure according to an embodiment of the invention.

Fig. 2 is an exploded schematic view of the ball screw structure of fig. 1.

FIG. 3 is a cross-sectional view of a nut and a two-piece return tube of the ball screw structure of FIG. 1 taken along cut line 3-3.

FIG. 4 is an enlarged partial cross-sectional view of the nut and two-piece manifold of FIG. 3 taken along section line 3-3.

FIG. 5 is a cross-sectional view of the nut and two-piece reflow tube of FIG. 3 taken along cut line 4-4.

FIG. 6 is an enlarged schematic view of the two-piece return tube of the ball screw arrangement of FIG. 2.

Figure 7 is an exploded view of the two-piece return tube of figure 6.

Fig. 8 is an exploded view of a two-piece return tube according to another embodiment of the present invention.

Figure 9 is an assembled view of the two-piece return tube of figure 8.

Figure 10 is an exploded view of a two-piece return tube according to yet another embodiment of the present invention.

Figure 11 is an assembled view of the two-piece return tube of figure 10.

Fig. 12 is a partial cross-sectional view of a ball screw structure according to yet another embodiment of the present invention. And

fig. 13 is a partial cross-sectional view of a ball screw structure according to a further embodiment of the present invention.

Description of the reference numerals:

100 ball screw structure

200 screw

210 external thread groove

300 screw cap

310. 310c, 310d mounting holes

320 inner thread groove

321 groove edge

330 bearing end face

331. 331c, 331d first section

332. 332c, 332d second section

400. 400a, 400b two-piece return pipe

500. 500a first combined member

510. 510a first tubular body

530. 530a first side trench

540 external fitting concave

550 inner engaging recess

560a, 560b holes

600. 600a second combined member

610. 610a second tube

620 feet part

621. 621c, 621d cylindrical body

622. 622c, 622d cylindrical channel

6211 spade-shaped connecting segment

6212 abutting end face

6213 the first zone

6214 second zone

6215. 6215c, 6215d inner wall surface

630. 630a second side trench

640 outer flange

650 inner flange

660a, 660b latch

661a, 661b convex segment

662a, 662b are convexly rounded

B1 ball

Center of C1

Distance D1

Length D2, D3

D4 and D5 wall thickness

I1 center axis

I2 center axis

I3 axial direction

L1, L2, L3 and L4 connecting wires

Tangential direction of motion of R1

S1 offset space

Acute angle of theta 1

Detailed Description

Embodiments of the present invention will be described below with reference to the drawings. For the purpose of clarity, numerous implementation details are set forth in the following description. However, the reader should understand that these implementation details should not be used to limit the invention. That is, in some embodiments of the invention, such implementation details are not necessary. In addition, for the sake of simplicity, some well-known and conventional structures and components are shown in the drawings in a simple schematic manner; and duplicate components will likely be referred to using the same reference numerals.

Referring to fig. 1, fig. 2, fig. 3, fig. 4, fig. 5, fig. 6 and fig. 7, wherein fig. 1 is a perspective view of a ball screw structure 100 according to an embodiment of the present invention, fig. 2 is an exploded view of the ball screw structure 100 of fig. 1, fig. 3 is a cross-sectional view of a nut 300 and a two-piece return pipe 400 of the ball screw structure 100 of fig. 1 along a section line 3-3, fig. 4 is a partially enlarged cross-sectional view of the nut 300 and the two-piece return pipe 400 of fig. 3 along a section line 3-3, fig. 5 is a cross-sectional view of the nut 300 and the two-piece return pipe 400 of fig. 3 along a section line 4-4, fig. 6 is an enlarged view of the two-piece return pipe 400 of the ball screw structure 100 of fig. 2, and fig. 7 is an exploded view of the two-piece return pipe 400 of fig. 6. The ball screw structure 100 includes a screw 200, a nut 300, a plurality of balls B1 (see fig. 4), and a two-piece return tube 400.

The screw 200 includes an external thread groove 210, the nut 300 is disposed on the screw 200 and has an axial direction I3, the nut 300 includes two mounting holes 310 and an internal thread groove 320, the internal thread groove 320 corresponds to the external thread groove 210 to form a load channel (not shown), and the ball B1 rolls on the load channel. The two-piece return tube 400 is disposed on the nut 300 and communicates with the load channel to allow each ball B1 to enter the interior of the two-piece return tube 400, the two-piece return tube 400 includes a first combination member 500 and a second combination member 600; the second combination member 600 is combined with the first combination member 500 and includes two legs 620 for being inserted into the two mounting holes 310, respectively, each leg 620 includes a cylindrical body 621 and a cylindrical channel 622, the cylindrical channel 622 penetrates through the cylindrical body 621, the cylindrical channel 622 is provided for each ball B1 to enter, and an offset space S1 (see fig. 4) is provided in the cylindrical channel 622 for each ball B1 to enter the cylindrical channel 622 along a tangential direction of movement R1 (see fig. 4).

Therefore, the ball B1 enters the cylindrical passage 622 in the tangential direction of movement R1 through the offset space S1, and the smoothness of rolling of the ball B1 can be increased. The details of the structure of the ball screw structure 100 will be described later.

The external thread groove 210 of the screw 200 is an arc-shaped groove structure formed along the thread of the screw 200, and the internal thread groove 320 of the nut 300 is also an arc-shaped groove structure and can be combined with the external thread groove 210 to form a tubular space, which is a load channel for the balls B1 to roll through in sequence.

The mounting hole 310 of the nut 300 penetrates through a body of the nut 300 and includes a bearing end surface 330 (see fig. 5), the internal thread groove 320 communicates with the two mounting holes 310 and the internal thread groove 320 is respectively connected with the two bearing end surfaces 330 by two groove edges 321 (see fig. 5), and a connecting line L3 of a center C1 of the two mounting holes 310 and an axial direction I3 of the nut 300 form an acute angle θ 1. In other words, since the internal thread groove 320 is distributed on the inner wall of the nut 300, when the mounting hole 310 penetrates through the body of the nut 300 along a radial direction (not shown) of the nut 300, the internal thread groove 320 is cut into a discontinuous state, and the cut portion forms the bearing end surface 330 and the groove edge 321.

The two mounting holes 310 are used for inserting the two legs 620 of the two-piece return tube 400, and when the screw 200 rotates relative to the screw cap 300, the balls B1 sequentially enter the cylindrical channel 622 of one leg 620 from the load channel, and then return to the load channel from the cylindrical channel 622 of the other leg 620, thereby allowing the screw cap 300 and the screw 200 to be displaced relative to each other. In addition, although the embodiment describes only one two-piece type return pipe 400, since the number of the mounting holes 310 is four, two-piece type return pipes 400 may be provided, and in other embodiments, the number of the two-piece type return pipes 400 and the number of the mounting holes 310 may be provided according to the requirement, which are sequentially arranged on the nut 300 to circulate the guide balls B1, which is not limited to the above disclosure.

The two-piece return tube 400 is composed of a first assembly member 500 and a second assembly member 600, the first assembly member 500 includes a first tube 510 and a first side groove 530, the first side groove 530 is concavely disposed on the first tube 510; the second assembly member 600 includes a second tube 610, a second side groove 630 and two legs 620, the second tube 610 corresponds to the first tube 510, the second side groove 630 is recessed in the second tube 610, the second side groove 630 and the first side groove 530 form a ball channel, and the two legs 620 are respectively connected to two opposite ends of the second tube 610. The first tube 510 of the first assembly member 500, the first side groove 530, the second tube 610 of the second assembly member 600, the second side groove 630 and the two legs 620 form a curved hollow tube structure for guiding the ball B1.

In detail, one end of the cylindrical body 621 is connected to the second tube 610 and the other end thereof includes a top-contacting end face 6212 contacting the bearing end face 330, the cylindrical passage 622 penetrates the cylindrical body 621 to form an inner wall face 6215, and the cylindrical body 621 of each foot 620 is integrally formed with the second tube 610, and in order to enable the ball B1 of the load channel to smoothly enter the cylindrical passage 622 in the foot 620, an inner side of the cylindrical body 621 facing the other foot 620 has a notch and the wall thickness decreases gradually to form a shovel-shaped engagement section 6211 corresponding to the external thread groove 210, so that the cylindrical body 621 and the external thread groove 210 can have a better engagement relationship to guide the ball B1 to enter the cylindrical passage 622.

In this embodiment, each ball B1 has a ball diameter value, each cylindrical body 621 has a central axis I1, each cylindrical channel 622 has a central axis I2 and a channel diameter value, a difference is equal to the channel diameter value minus the ball diameter value, wherein a connecting line L2 of the two central axes I2 intersects a connecting line L1 of the two central axes I1, and the central axis I2 of the same foot 620 is closer to the offset space S1 than the central axis I1 and has a distance D1 from the central axis I1 smaller than or equal to the difference.

In detail, in the case of omitting the spade-shaped connecting segment 6211, the cylindrical body 621 has a cylindrical structure (i.e. the projection profile of the cylindrical body 621 is generally circular) and a central axis I1 (the center corresponds to the center of the circle), and the cylindrical passage 622 has a cylindrical structure and thus a central axis I2. In order to generate the offset space S1 for the ball B1 to enter the cylindrical passage 622 from the tangential direction of movement R1, in the present embodiment, the cylindrical passage 622 is offset, that is, the cylindrical passage 622 and the cylindrical body 621 are not concentric, so that the central axis I1 is parallel to and does not coincide with the central axis I2, and therefore the wall thickness D4 is smaller than the wall thickness D5. When the distance D1 is less than or equal to the difference, it means that sufficient offset space S1 can be generated to move the ball B1 along the tangential direction of motion R1, and at the same time, the situation that the ball B1 cannot enter the cylindrical channel 622 due to excessive offset of the cylindrical channel 622 can be avoided. Preferably, the distance D1 may be less than or equal to 1mm and greater than or equal to 0.05 mm. Therefore, the effect of reducing noise can be achieved. In other embodiments not shown in the drawings, the cylindrical body may be an elliptic cylindrical structure or a long elliptic cylindrical structure, and the projected contour may be composed of an outer circular arc, an inner circular arc and a line segment connecting the outer circular arc and the inner circular arc, so that the central axis is an extension line of a central point of a connecting line between the center of the outer circular arc and the center of the outer circular arc along the radial direction (the radial direction of the nut 300), which includes but is not limited to the above.

In addition, as shown in fig. 5, since the two legs 620 are respectively located at two sides of the nut 300, the ball B1 has a tangential direction of movement R1 and another tangential direction opposite to the tangential direction of movement R1 (i.e. the two directions are parallel but opposite), so the offset directions of the two cylindrical channels 622 must be opposite, and the connecting line L2 of the two central axes I2 and the connecting line L1 of the two central axes I1 are crossed.

In addition, since the cylindrical body 621 is used to insert into the mounting hole 310, the shape of the cylindrical body 621 and the mounting hole 310 are corresponding to each other, and since the cylindrical channel 622 is offset to form the offset space S1, the mounting hole 310 does not need to be offset, so that the central axis I1 penetrates through the center C1 of the mounting hole 310 after the cylindrical body 621 is inserted into the mounting hole 310.

The abutting end face 6212 of any of the cylindrical bodies 621 may include a first section 6213 and a second section 6214, the first section 6213 is adjacent to the offset space S1, the second section 6214 is far from the offset space S1, the abutting end face 330 of the nut 300 includes a first section 331 and a second section 332, the first section 331 is used for the first section 6213 to abut against, the second section 332 is used for the second section 6214 to abut against, and under the condition that the mounting hole 310 does not need to be offset, an end length D2 of the first section 331 is equal to an end length D3 of the second section 332.

The abutting end face 6212 of the cylindrical body 621 means the end face of the other end of the cylindrical body 621 away from the spade-shaped engaging section 6211, and the mounting hole 310 is opened along the radial direction, so that a portion of the mounting hole 310 penetrates the body of the nut 300, another portion of the mounting hole 310 does not penetrate the body of the nut 300 to form the abutting end face 330, and the abutting end face 330 is adjacent to the groove edge 321 of the internal thread groove 320, the end edge of the first section 331 means the edge of the abutting end face 330 on one side of the internal thread groove 320, the end edge of the second section 332 means the edge of the abutting end face 330 on the other side of the internal thread groove 320, and the end edge length D2 of the first section 331 is equal to the end edge length D3 of the second section 332.

The offset of the central axis I2 causes the inner wall 6215 to move away from the groove edge 321 in the axial direction I3 to form an offset space S1 in the cylindrical passage 622 for each ball B1 to enter the cylindrical passage 622 in the tangential direction of motion R1. Therefore, as shown in fig. 4, when the ball B1 moves along the tangential direction of motion R1 and enters the cylindrical passage 622, due to the existence of the offset space S1, the ball B1 can continue to move along the tangential direction of motion R1, thereby avoiding forcing it to change direction directly to hit the cylindrical passage 622, so as to increase the smoothness of the ball B1 flow, and reduce the noise generated by the hit, and at the same time, because the hit force or chance is reduced, the nut 300 and the two-piece return pipe 400 can be prevented from being damaged, thereby increasing the service life thereof.

In order to allow the balls B1 to enter and exit the load path and the ball path more smoothly, the central axis I2 should be offset in the direction parallel to the axial direction I3, and when the line L4 between the central axis I2 and the central axis I1 of the same leg 620 and the line L1 between the two central axes I1 form an acute angle θ 1, the offset direction of the central axis I2 is parallel to the axial direction I3 when the two-piece return pipe 400 is mounted in the mounting hole 310, which helps to improve the smoothness of the movement of the balls B1.

As shown in fig. 7, in the two-piece return tube 400, the first combining member 500 may further include an outer engaging recess 540 and an inner engaging recess 550, the outer engaging recess 540 is disposed on the first tube 510, the outer engaging recess 540 is disposed outside the first side groove 530 and faces the second tube 610, the inner engaging recess 550 is disposed on the first tube 510, and the inner engaging recess 550 is disposed inside the first side groove 530 and faces the second tube 610; the second assembly member 600 further includes an outer flange 640 and an inner flange 650, the outer flange 640 is disposed on the second tube 610, the outer flange 640 is located outside the second side groove 630 and corresponds to the outer engaging recess 540, the outer flange 640 is engaged with the outer engaging recess 540, the inner flange 650 is disposed on the second tube 610, the inner flange 650 is located inside the second side groove 630 and corresponds to the inner engaging recess 550, and the inner flange 650 is engaged with the inner engaging recess 550. Alternatively, the outer fitting recess 540 and the outer flange 640 may be connected together by ultrasonic welding, and the inner fitting recess 550 and the inner flange 650 may be connected together by ultrasonic welding.

In the embodiment, the outer engaging recess 540 and the inner engaging recess 550 are disposed adjacent to both sides of the first side groove 530, the outer flange 640 and the inner flange 650 are disposed adjacent to both sides of the second side groove 630, the outer engaging recess 540 and the outer flange 640 may be connected together by ultrasonic welding, and the inner engaging recess 550 and the inner flange 650 may be connected together by ultrasonic welding, so that the first assembling member 500 and the second assembling member 600 are fixedly connected. In other embodiments, the outer engaging recess 540 and the inner engaging recess 550 may have a distance from both sides of the first side groove 530, and the outer flange 640 and the inner flange 650 may have a distance from both sides of the second side groove 630, so that the combining strength of the first combination member 500 and the second combination member 600 may be increased, and the first combination member 500 and the second combination member 600 may be prevented from being separated due to the impact of the ball B1.

Referring to fig. 8 and 9, fig. 8 is an exploded view of a two-piece return pipe 400a according to another embodiment of the present invention, and fig. 9 is an assembled view of the two-piece return pipe 400a of fig. 8. The structure of the two-piece return pipe 400a is similar to the structure of the two-piece return pipe 400 described in fig. 1 to 7, and the differences are described below.

The first combination member 500a can further include a hole 560a, the hole 560a penetrates the first tube 510a and is located outside the first side groove 530 a; the second assembly member 600a may further include a tenon 660a, the tenon 660a is protruded from the second tube 610a, the tenon 660a is located outside the second side groove 630a and corresponds to the hole 560a, the tenon 660a includes a protruding section 661a and a convex circle 662a, the protruding section 661a protrudes toward the first tube 510a and has a D-shaped cross section, and the convex circle 662a connects the protruding section 661 a; the tenon 660a penetrates through the hole 560a, and the convex circle 662a is limited to combine the first tube 510a and the second tube 610 a.

In this embodiment, two caps are formed on the left and right sides of the first pipe 510a, the number of the holes 560a is two, the two holes 560a are respectively located on the two caps and face the second pipe 610a, the two caps are also formed on the left and right sides of the second pipe 610a, the number of the tenons 660a is two and correspond to the holes 560a, and the tenons 660a are respectively located on the two caps and protrude toward the first pipe 510 a. Therefore, when the first combination member 500a and the second combination member 600a are combined, the convex circle 662a of the tenon 660a is limited after passing through the hole 560a, so that the first tube 510a and the second tube 610a cannot be separated, thereby completing the assembly of the two-piece return tube 400 a.

Referring to fig. 10 and 11, fig. 10 is an exploded view of a two-piece return pipe 400b according to another embodiment of the present invention, and fig. 11 is an assembled view of the two-piece return pipe 400b of fig. 10. The structure of the two-piece return tube 400b is similar to the two-piece return tube 400a described in fig. 8 and 9, except that the hole 560b has a D-shaped cross-section, so that the hole 560b can have a flat surface that fits against a flat surface of the protruding section 661b of the latch 660b, further contributing to the retention of the bead 662 b.

Referring to fig. 12, fig. 12 is a partial cross-sectional view of a ball screw structure according to still another embodiment of the present invention. In this embodiment, the cylindrical channel 622c is not offset-opened on the cylindrical body 621c, but the mounting hole 310c is offset-opened, that is, the wall thickness D4 is equal to the wall thickness D5, and the end edge length D2 of the first section 331c is greater than the end edge length D3 of the second section 332c, so when the cylindrical body 621c is placed in the mounting hole 310c, the inner wall 6215c is axially away from the groove edge to form an offset space S1 in the cylindrical channel 622 c.

Referring to fig. 13, fig. 13 is a partial sectional view of a ball screw structure according to a further embodiment of the present invention. In this embodiment, the cylindrical passage 622d is offset from the cylindrical body 621d, but the offset direction is opposite to the offset direction of the cylindrical passage 622 in fig. 1 to 5, and the mounting hole 310d is also offset. That is, the wall thickness D4 is greater than the wall thickness D5, the end edge length D2 of the first segment 331D is greater than the end edge length D3 of the second segment 332D, the wall thickness D4 is less than the end edge length D2 of the first segment 331D and the wall thickness D5 is greater than the end edge length D3 of the second segment 332D. Therefore, when the cylindrical body 621d is placed in the mounting hole 310d, the inner wall surface 6215d is axially away from the groove edge to form an offset space S1 in the cylindrical passage 622 d. In other embodiments not shown in the drawings, the offset direction of the cylindrical channel may be the same as the offset direction of the mounting hole, as long as the inner wall surface is axially away from the groove edge to form an offset space, which is not limited to the above disclosure.

In the above embodiment, the offset space is provided in the cylindrical channel for each ball to enter the cylindrical channel along a tangential direction of movement, so that the ball can enter the cylindrical channel more smoothly, and the offset space can be formed by making the inner wall surface away from the groove edge along the axial direction, so that the inner wall surface can be away from the groove edge by at least one of offsetting the mounting hole from the inner thread groove and offsetting the cylindrical channel from the cylindrical body. In addition, because the second combined component of the two-piece type return pipe comprises two complete feet, the structural strength can be enhanced, the noise is reduced, and the service life of the ball screw structure is prolonged.

While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims (8)

1. A ball screw structure comprising:

a screw rod comprising an external thread groove;

a nut disposed around the threaded rod and having an axial direction, the nut comprising:

The two mounting holes penetrate through a body of the nut, and each mounting hole comprises a bearing end face; and

the internal thread groove corresponds to the external thread groove to form a load channel, is communicated with the two mounting holes and is respectively connected with the two bearing end surfaces by two groove edges;

a plurality of balls rolling in the load channels; and

a two-piece return tube disposed in said nut and in communication with said load path to allow each of said balls to enter said two-piece return tube, said two-piece return tube comprising:

a first assembly member comprising:

a first tube; and

the first side groove is concavely arranged on the first pipe body; and

a second combining member combined with the first combining member and comprising:

the second pipe body corresponds to the first pipe body and comprises a second side groove, and the first side groove and the second side groove are combined to form a ball channel; and

two feet, connect respectively the relative both ends of second body and be used for inserting each the mounting hole, each the foot contains:

one end of the columnar body is connected with the second pipe body, and the other end of the columnar body comprises a top abutting end surface which abuts against the bearing end surface; and

The cylindrical channel penetrates through the cylindrical body to form an inner wall surface, and each ball is led to the ball channel from the internal thread groove through the cylindrical channel;

the inner wall surface is far away from the groove edge along the axial direction so as to form an offset space in the cylindrical channel for each ball to enter the cylindrical channel along a motion tangential direction;

each ball has a ball diameter value, each cylindrical body has a central axis, each cylindrical passage has a central axis and a passage diameter value, a difference value is equal to the passage diameter value minus the ball diameter value, wherein a connection line of the two central axes intersects a connection line of the two central axes, and the central axis of the same foot is closer to the offset space than the central axis and has a distance from the central axis less than or equal to the difference value.

2. The ball screw structure of claim 1, wherein the distance is greater than or equal to 0.05mm and less than or equal to 1 mm.

3. The ball screw structure of claim 1, wherein each of the abutting end faces comprises:

A first region adjacent to the bias space; and

a second region remote from the bias space; and is

Each bearing end surface comprises:

a first section for the first zone to bear against; and

and the second section is used for bearing the second zone, and the length of one end edge of the first section is greater than that of one end edge of the second section.

4. The ball screw structure of claim 1,

the first combining member further includes:

the outer embedding groove is arranged on the first pipe body, is positioned on the outer side of the first side groove and faces the second pipe body; and

the inner embedding groove is arranged on the first pipe body, is positioned on the inner side of the first side groove and faces the second pipe body; and is

The second combination member further comprises:

the outer flange is arranged on the second pipe body, is positioned on the outer side of the second side groove and corresponds to the outer embedding concave, and is embedded with the outer embedding concave; and

the inner flange is arranged on the second pipe body, is positioned on the inner side of the second side groove and corresponds to the inner embedding concave, and is embedded with the inner embedding concave.

5. The ball screw structure according to claim 4, wherein the outer fitting recess and the outer flange are joined integrally by ultrasonic welding, and the inner fitting recess and the inner flange are joined integrally by ultrasonic welding.

6. The ball screw structure of claim 1,

the first combining member further includes:

the hole penetrates through the first pipe body and is positioned outside the first side groove; and is

The second combination member further comprises:

a trip, the protruding locate the second body, the trip is located second side slot outside and position correspond the hole, the trip contains:

the protruding section protrudes towards the first pipe body and is provided with a D-shaped section; and

a convex circle connected with the convex section;

wherein the tenon passes through the hole, and the convex circle is limited to enable the first pipe body and the second pipe body to be combined.

7. The ball screw structure of claim 6, wherein the cross-section of the hole is D-shaped.

8. A ball screw structure comprising:

a screw rod comprising an external thread groove;

the screw cap is sleeved on the screw rod and is provided with an axial direction, the screw cap comprises two mounting holes and an internal thread groove, and the internal thread groove corresponds to the external thread groove to form a load channel;

A plurality of balls rolling in the load channels; and

a two-piece return tube disposed in said nut and in communication with said load path to allow each of said balls to enter said two-piece return tube, said two-piece return tube comprising:

a first combination member; and

a second combination member combined with the first combination member and including two leg portions for being inserted into each of the mounting holes, respectively, each of the leg portions including:

a columnar body; and

the cylindrical channel penetrates through the cylindrical body, each ball can enter the cylindrical channel, and an offset space is formed in the cylindrical channel, so that each ball can enter the cylindrical channel along a motion tangential direction;

each ball has a ball diameter value, each cylindrical body has a central axis, each cylindrical passage has a central axis and a passage diameter value, a difference value is equal to the passage diameter value minus the ball diameter value, wherein a connection line of the two central axes intersects a connection line of the two central axes, and the central axis of the same foot is closer to the offset space than the central axis and has a distance from the central axis less than or equal to the difference value.

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