Composite raceway ball screw pair

Abstract

The invention discloses a composite raceway ball screw pair. The composite raceway ball screw pair comprises a ball screw, a ball nut, a plurality of first steel balls, a plurality of second steel balls, a first ball return pipe and a second ball return pipe. A spiral pipeline is formed between the ball screw and the ball nut and comprises a top-layer double-arc spiral raceway and a bottom-layer double-arc spiral raceway; the top-layer double-arc spiral pipeline is suitable for rolling of a first steel ball, the bottom-layer double-arc spiral raceway is suitable for rolling of a second steel ball, and the diameter of the first steel ball is larger than that of the second steel ball; the first ball return pipe is used for rolling backflow of the first steel balls, and the second ball return pipe is used for rolling backflow of the second steel balls. According to the invention, the threaded raceway between the ball screw and the ball nut is designed into a double-layer double-arc form, and the contact stress between the steel ball and the ball screw raceway is dispersed to the double-layer spiral raceway during loading operation, so that the fatigue wear of the steel ball to the raceway is greatly reduced, and the service life of the ball screw pair is prolonged.

Description

Technical Field

[0001] This invention belongs to the field of precision transmission technology, and particularly relates to a composite raceway ball screw pair. Background Technology

[0002] A ball screw assembly consists of a ball screw, a ball nut, a ball return device, and multiple steel balls.

[0003] In existing technologies, ball screws are much longer than ball nuts. Improving the raceway hardness of ball screws through carburizing and quenching is extremely difficult and costly. Furthermore, carburizing and quenching results in severe bending deformation of the ball screw, making subsequent helical raceway grinding impossible. Therefore, the surface hardness of ball screw raceways is often improved through induction hardening. Ball nuts, being shorter, can have their raceway surface hardness improved through carburizing and quenching. Under the same hardness conditions, the wear resistance of helical raceways processed by carburizing and quenching is significantly better than that of helical raceways processed by induction hardening. This leads to fatigue failure of the ball screw pair during use, causing the ball screw raceway to fail before the ball nut raceway, resulting in functional failure of the ball screw pair. For various servo presses, servo injection molding machines, and other equipment using ball screw pairs, the lifespan of the ball screw pair, as the core component for achieving transmission functions, determines the lifespan of the equipment. Therefore, given that the existing heat treatment method for the helical raceway surface of ball screws cannot be changed, it is necessary to design a new type of ball screw pair to improve the service life of the ball screw pair in order to meet the current demand for long service life of various equipment. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a composite raceway ball screw assembly that addresses the shortcomings of the prior art, including a ball screw, a ball nut, a plurality of first steel balls, a plurality of second steel balls, a first return ball tube, a second return ball tube, and a return ball tube pressure plate.

[0005] The return ball pressure plate fixes the first and second return ball tubes onto the ball nut.

[0006] A spiral channel is formed between the ball screw and the ball nut. The spiral channel includes a top double-circular-arc spiral raceway and a bottom double-circular-arc spiral raceway.

[0007] The top-layer double-arc spiral pipe is suitable for the rolling of the first steel ball, and the bottom-layer double-arc spiral raceway is suitable for the rolling of the second steel ball. The diameter of the first steel ball is larger than the diameter of the second steel ball, and the pitch circle diameter of the rolling operation of the first steel ball is larger than the pitch circle diameter of the rolling operation of the second steel ball.

[0008] The first return bead tube is connected to the top double-arc spiral pipe in a loop. The first return bead tube is used for the cyclic rolling return of the first steel ball. The second return bead tube is connected to the bottom double-arc spiral pipe in a loop. The second return bead tube is used for the cyclic rolling return of the second steel ball.

[0009] In one possible implementation, the spiral pipe further includes a double-layer raceway transition zone, which is located between the top double-arc spiral raceway and the bottom double-arc spiral raceway. The double-layer raceway transition zone separates the top double-arc spiral raceway from the bottom double-arc spiral raceway, and neither the first steel ball nor the second steel ball comes into contact with the double-layer raceway transition zone during rolling.

[0010] In one possible implementation, the spiral pipe also includes a lubricating oil groove, which is formed on the bottom double-arc spiral raceway and is used to store lubricating oil.

[0011] Compared with the prior art, the present invention has the following advantages: The present invention provides a composite raceway ball screw assembly, including a ball screw, a ball nut, multiple first steel balls, multiple second steel balls, a first return ball tube, and a second return ball tube; a spiral channel is formed between the ball screw and the ball nut, the spiral channel including a top double-arc spiral raceway and a bottom double-arc spiral raceway; the top double-arc spiral raceway is suitable for the rolling of the first steel balls, and the bottom double-arc spiral raceway is suitable for the rolling of the second steel balls, the diameter of the first steel balls is larger than the diameter of the second steel balls; the first return ball tube is used for rolling back the first steel balls, and the second return ball tube is used for rolling back the second steel balls. The present invention designs the threaded raceway between the ball screw and the ball nut as a double-layer double-arc form, the top double-arc raceway is designed to accommodate the running of the larger-sized first steel balls, and the bottom double-arc raceway is designed to accommodate the running of the slightly smaller-sized second steel balls. Compared to ordinary single double-circular-arc ball screws, this invention disperses the contact stress between the steel ball and the ball screw raceway to a double-layer helical raceway during loaded operation, significantly reducing fatigue wear of the steel ball on the raceway and thus improving the service life of the ball screw pair.

[0012] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of a composite raceway ball screw pair according to the present invention; Figure 2 This is a schematic diagram of the operation of the first steel ball 03 of a composite raceway ball screw pair of the present invention on the top double circular arc spiral raceway 08. Figure 3 This is a schematic diagram of the operation of the second steel ball 04 of a composite raceway ball screw pair of the present invention on the bottom double circular arc spiral raceway 09. Figure 4This is a schematic diagram of the normal section of the double-layer helical raceway of a composite raceway ball screw pair according to the present invention.

[0014] Explanation of reference numerals in the attached figures: . Detailed Implementation

[0015] To address the problem of short service life in ball screw assemblies, embodiments of the present invention provide a composite raceway ball screw assembly, such as... Figure 1 As shown, the composite raceway ball screw assembly may include a ball screw 01, a ball nut 02, multiple first steel balls 03, multiple second steel balls 04, a first return ball tube 05, a second return ball tube 06, and a return ball tube pressure plate 07. The return ball tube pressure plate 07 fixes the first return ball tube 05 and the second return ball tube 06 to the ball nut 02.

[0016] Among them, a spiral channel is formed between the ball screw 01 and the ball nut 02, and the spiral channel includes a top double circular arc spiral raceway 08 and a bottom double circular arc spiral raceway 09.

[0017] The top-layer double-arc spiral pipe 08 is suitable for the rolling of the first steel ball 03, and the bottom-layer double-arc spiral raceway 09 is suitable for the rolling of the second steel ball 04. The diameter of the first steel ball 03 is larger than the diameter of the second steel ball 04, and the pitch circle diameter of the first steel ball 03 is larger than the pitch circle diameter of the second steel ball 04. For ease of understanding, let's use... Figure 2 , Figure 3 For example, among which, Figure 2 This is a schematic diagram showing the movement of the first steel ball 03 on the top double-arc spiral raceway 08. Figure 3 This is a schematic diagram of the movement of the second steel ball 04 on the bottom double circular arc spiral raceway 09.

[0018] The first return bead pipe 05 is circulatedly connected to the top double-arc spiral pipe 08. The first return bead pipe 05 is used for circulated rolling back of the first steel ball 03. The second return bead pipe 06 is circulatedly connected to the bottom double-arc spiral pipe 09. The second return bead pipe 06 is used for circulated rolling back of the second steel ball 04.

[0019] In this embodiment of the invention, the threaded raceway between the ball screw 01 and the ball nut 02 is designed as a double-layer, double-arc type. The top double-arc spiral raceway 08 is designed to accommodate the operation of the larger first steel ball 03, while the bottom double-arc spiral raceway 09 is designed to accommodate the operation of the slightly smaller second steel ball 04. Compared to a conventional single double-arc raceway ball screw, this embodiment of the invention distributes the contact stress between the steel ball and the ball screw raceway to the double-layer spiral raceway during loaded operation, significantly reducing fatigue wear of the steel ball on the raceway and thus improving the service life of the ball screw pair. Furthermore, in this embodiment of the invention, after the service life of the composite raceway ball screw pair expires, by replacing the ball screw with a new one, the first return ball tube and the second return ball tube are swapped in the installation position of the ball nut, and a new second steel ball 04 and a new first steel ball 03 are reinstalled. The original ball nut 02 can be reused, achieving the same effect as a new ball nut without replacing it, thereby significantly reducing the overall manufacturing cost of the ball screw pair. Therefore, the composite raceway ball screw pair in this embodiment of the invention also has the advantage of low operating cost.

[0020] In one possible implementation, such as Figure 4 As shown, the spiral pipe also includes a double-layer raceway transition zone 10, which is located between the top double-arc spiral raceway 08 and the bottom double-arc spiral raceway 09. The double-layer raceway transition zone 10 separates the top double-arc spiral raceway 08 and the bottom double-arc spiral raceway 09. The first steel ball 03 and the second steel ball 04 do not contact the double-layer raceway transition zone 10 when rolling.

[0021] like Figure 4 As shown, in the top-layer double-arc spiral raceway 08, the first steel ball 03 has a running contact angle of α, and the radius of the top-layer double-arc spiral raceway 08 is R1. The first steel ball 03 runs in the top-layer double-arc spiral raceway 08 and has a gap with the bottom-layer double-arc spiral raceway 09, without making contact at all. In the bottom-layer double-arc spiral raceway 09, the second steel ball 04 has a running contact angle of β, and the radius of the bottom-layer double-arc spiral raceway 09 is R2. The second steel ball 04 runs in the bottom-layer double-arc spiral raceway 09 and has a gap with the top-layer double-arc spiral raceway 08, without making contact at all. The diameter of the first steel ball 03 is slightly larger than the diameter of the second steel ball 04, and the pitch circle diameter of the first steel ball 03 is also slightly larger than the pitch circle diameter of the second steel ball 04.

[0022] In one possible implementation, the spiral pipe also includes a lubricating oil groove 11, which is formed on the bottom double circular arc spiral raceway 09 and is used to store lubricating oil.

[0023] To facilitate understanding of the invention, the working principle of the invention will be further explained below.

[0024] Combination Figures 1-4 The return ball tube pressure plate 07 fixes the first return ball tube 05 and the second return ball tube 06 onto the ball nut 02.

[0025] When the composite raceway ball screw pair of the present invention is running, the first steel ball 03 reciprocates in the circulation channel formed by the top double circular arc spiral raceway 08 and the first return ball tube 05 between the ball screw 01 and the ball nut 02; the second steel ball 04 reciprocates in the circulation channel formed by the bottom double circular arc spiral raceway 09 and the second return ball tube 06 between the ball screw 01 and the ball nut 02.

[0026] A double-layer raceway transition zone 10 is provided between the top-layer double-arc spiral raceway 08 and the bottom-layer double-arc spiral raceway 09, which separates the top-layer double-arc spiral raceway 08 and the bottom-layer double-arc spiral raceway 09. The first steel ball 03 and the second steel ball 04 never come into contact with the double-layer raceway transition zone 10 at any time. When the first steel ball 03 is running on the top-layer double-arc spiral raceway 08 between the ball screw 01 and the ball nut 02, there is a large gap between it and the bottom-layer double-arc spiral raceway 09, and it does not come into contact with the bottom-layer double-arc spiral raceway 09; similarly, when the second steel ball 04 is running on the bottom-layer double-arc spiral raceway 09 between the ball screw 01 and the ball nut 02, there is a large gap between it and the top-layer double-arc spiral raceway 08, and it does not come into contact with the top-layer double-arc spiral raceway 08.

[0027] Under the same load, the composite raceway ball screw pair of the present invention disperses the contact stress between the first steel ball 03, the second steel ball 04 and the helical raceway of the ball screw 01 into two layers, which greatly reduces the fatigue wear of the steel balls on the helical raceway of the ball screw 01, extends the service life of the ball screw, and thus extends the service life of the ball screw pair.

[0028] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A composite raceway ball screw pair, characterized in that, It includes a ball screw, ball nuts, multiple first steel balls, multiple second steel balls, a first return ball tube, a second return ball tube, and a return ball tube pressure plate. The return ball pressure plate fixes the first and second return ball tubes onto the ball nut. A spiral channel is formed between the ball screw and the ball nut, and the spiral channel includes a top double-arc spiral raceway and a bottom double-arc spiral raceway. The top-layer double-arc spiral pipe is suitable for the first steel ball to roll, and the bottom-layer double-arc spiral raceway is suitable for the second steel ball to roll. The diameter of the first steel ball is larger than the diameter of the second steel ball, and the pitch circle diameter of the first steel ball rolling is larger than the pitch circle diameter of the second steel ball rolling. The first return bead tube is circulatedly connected to the top double-arc spiral pipe, and the first return bead tube is used for circulated rolling return of the first steel ball. The second return bead tube is circulatedly connected to the bottom double-arc spiral pipe, and the second return bead tube is used for circulated rolling return of the second steel ball.

2. The composite raceway ball screw assembly according to claim 1, characterized in that, The spiral pipe also includes a double-layer raceway transition zone, which is located between the top double-arc spiral raceway and the bottom double-arc spiral raceway. The double-layer raceway transition zone separates the top double-arc spiral raceway from the bottom double-arc spiral raceway, and neither the first steel ball nor the second steel ball comes into contact with the double-layer raceway transition zone when rolling.

3. The composite raceway ball screw pair according to claim 1 or 2, characterized in that, The spiral pipe also includes a lubricating oil groove, which is formed on the bottom double-arc spiral raceway and is used to store lubricating oil.

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