Dustproof ball return integrated ball screw pair and ball return channel design method thereof

Abstract

The application discloses a dustproof and ball-return integrated ball screw pair and a ball-return channel design method thereof. The ball screw pair comprises a screw rod, a first helical raceway is arranged on the outer circumferential surface of the screw rod; a nut, a ball-return part and a second helical raceway are arranged on the nut, the second helical raceway is arranged on the inner side wall of the nut and corresponds to the first helical raceway, and the two form a complete helical raceway, the ball-return part is arranged in the base wall of the nut and comprises a ball-return axial channel and two first half ball-return channels located at two ends of the ball-return axial channel; dustproof and ball-return integrated devices are respectively assembled at two ends of the nut, a dustproof tongue and a second half ball-return channel are arranged on the dustproof and ball-return integrated devices, the dustproof tongue is located at the middle position of the first helical raceway and is in clearance fit with the first helical raceway, the second half ball-return channel corresponds to the first half ball-return channel, and the two form a complete rotary channel; the rotary channel is in smooth communication with the ball-return axial channel and the helical raceway, so that a complete ball-return channel is formed; and a steel ball is rollingly assembled in the ball-return channel.

Description

Technical Field

[0001] This application relates to the field of ball screw pair technology, and in particular discloses a dustproof ball screw pair with integrated ball return and its ball return channel design method. Background Technology

[0002] Ball screw pairs are widely used in CNC machine tools, automated equipment, and other applications requiring precise linear transmission. They mainly consist of a screw, a nut, steel balls, and a circulation return device. To ensure the transmission accuracy and service life of the ball screw pair, dustproof devices are usually installed at both ends of the nut to prevent dust, chips, and other impurities from entering the raceway and causing wear. At the same time, a ball return device is also required to allow the steel balls to return from one end of the helical raceway to the other end, achieving continuous cyclic rolling.

[0003] In existing ball screw assembly designs, the dustproof device and the ball return device are usually two independent components, installed at opposite ends of the nut. This separate structure leads to the following technical problems: First, because the screw thread has a spiral rising structure, the dustproof tongue in the dustproof device needs to be precisely embedded in the thread raceway to effectively scrape off impurities. However, the spiral rising structure introduces phase accuracy requirements, that is, the dustproof tongue must maintain a specific circumferential phase relationship with the thread profile, otherwise it will lead to installation interference or dustproof failure. This greatly increases the difficulty of processing and assembling the dustproof device, and the assembly position is highly random, making it difficult to ensure the consistency of batch products. Secondly, traditional dustproof tongues typically use contact sealing with the thread raceway surface of the ball screw. When the ball screw pair is running at high speed and continuously, the sliding friction between the dustproof tongue and the raceway will generate a significant temperature rise, affecting transmission accuracy and product life. As the industry's requirements for the temperature rise of the ball screw pair during continuous operation become increasingly stringent, how to reduce the frictional temperature rise caused by the dustproof structure has become a technical problem that urgently needs to be solved. In addition, the dustproof device and the ball return device are designed and assembled separately, which results in complex structures at both ends of the nut, a large number of parts, and complicated assembly procedures. Furthermore, it is difficult to ensure the relative positional accuracy of the two in a coordinated manner, so improvements are needed. Summary of the Invention

[0004] The purpose of this application is to provide a dustproof ball screw assembly with integrated ball return mechanism.

[0005] Another objective of this application is to provide a method for designing the return ball channel of an integrated dustproof ball screw pair.

[0006] To achieve the above objectives, the technical solution adopted in this application is as follows: a dustproof ball screw assembly, comprising: a screw, wherein a first helical raceway is provided on the outer circumferential surface of the screw; a nut, wherein the nut is assembled on the screw and has a ball return portion and a second helical raceway, the second helical raceway being disposed on the inner wall of the nut and corresponding to the first helical raceway, the two forming a complete helical raceway, the ball return portion being disposed within the base wall of the nut, and comprising a ball return axial channel and two first half-ball return channels located at both ends of the ball return axial channel; and a dustproof ball return integrated device, wherein the dustproof ball return portion is disposed within the base wall of the nut and includes a ball return axial channel and two first half-ball return channels located at both ends of the ball return axial channel; and a dustproof ball return integrated device. The dust-proof ball return device is respectively assembled at both ends of the nut. The dust-proof ball return device is provided with a dust-proof tongue and a second half-ball return channel. The dust-proof tongue is located in the middle of the first helical raceway and the two are in clearance fit. The second half-ball return channel corresponds to the first half-ball return channel, and the two form a complete rotation channel. The rotation channel is smoothly connected to the ball return axial channel and the helical raceway, thereby forming a complete ball return channel. The steel ball is rolled and assembled in the ball return channel. When the nut moves relative to the lead screw, the steel ball is adapted to move along the ball return channel.

[0007] As a preferred embodiment, the integrated dustproof and ball return device includes a dustproof main ring, a ball return main body, a spiral ball deflector, and a ball return buffer. The ball return main body is fixedly disposed on one side of the dustproof main ring, the spiral ball deflector is fixedly disposed between the dustproof main ring and the ball return main body, and the ball return buffer is fixedly disposed on the ball return main body. The dustproof tongue is spirally protruding and is fixedly disposed on the inner sidewall of the dustproof main ring, and is adapted to the first spiral raceway.

[0008] Further preferably, the second half-return channel is formed on the return ball body and the return ball buffer. The second half-return channel includes a first half-return channel straight section, a half-return channel arc reversal section and a second half-return channel straight section connected in sequence. The first half-return channel straight section is located on the return ball body, and the half-return channel arc reversal section and the second half-return channel straight section are located on the return ball buffer.

[0009] Preferably, the centerline of the spiral ball deflector and the centerline of the dustproof tongue are located on the same spiral line.

[0010] As a preferred embodiment, the centerline of the return channel of the second half-return channel is composed of three continuous segments: a straight line segment AB, an arc segment BC, and a straight line segment CD. In the XOZ plane, the projected center lines A'B'C'D' of the return ball channel centerline satisfy the equation of a straight line: , in, Let z be the pitch circle diameter of the ball screw assembly. b is a constant, determined based on the nut's structural dimensions and the diameter of the steel ball.

[0011] Further preferably, in the YOZ plane, the projected center line A”B”C”D” of the return ball channel center line consists of three consecutive segments, namely the straight line segment A”B”, the circular arc segment B”C”, and the straight line segment C”D”. With A” as the origin, the line segment A”B” satisfies the following equation: z = -cot(α)·y Where α is the helix angle of the ball screw pair, which satisfies P h The lead of the ball screw assembly; Arc segment B”C” is an arc with radius r, and the center point of the arc is O”. The coordinates of O” are (y = r, r ... c” , z o” ), where z o” =br, then the arc segment B”C” satisfies the equation: (yy c” ) 2 +(zz o” ) 2 =r 2 ; Line segment C”D” satisfies the equation of the line: z=b.

[0012] Further optimization, the arc segment B”C” is divided into two segments, namely the arc segment B”G” and the arc segment GC”; Wherein, the coordinate of G is ( , z o” ) The circular arc segment B”G satisfies the equation: , The circular arc segment "GC" satisfies the following equation: .

[0013] As a preferred embodiment, the nut is provided with mounting grooves at both ends. A first assembly groove, a second assembly groove, and a first half-return ball channel are formed within the mounting grooves. The first half-return ball channel includes a first straight half-return ball channel, an arc-shaped half-return ball channel, and a second straight half-return ball channel connected sequentially. The first straight half-return ball channel is smoothly connected to the second helical raceway, and the second straight half-return ball channel is smoothly connected to the axial return ball channel. When the dustproof return ball integrated device is assembled with the nut, the return ball body is embedded in the first assembly groove, and the return ball buffer is embedded in the second assembly groove, so that the first straight half-return ball channel, the arc-shaped half-return ball channel, and the second straight half-return ball channel respectively cooperate with the straight portion of the first half-return ball channel, the arc-shaped reversing portion of the half-return ball channel, and the straight portion of the second half-return ball channel to form a complete rotation channel.

[0014] More preferably, the two mounting grooves at both ends of the nut are rotationally symmetrically distributed with respect to the axial mid-section of the ball return axial channel at 180°.

[0015] A method for designing the return ball channel of an integrated dustproof ball screw pair includes the following steps: Step A: Determine the lead P of the ball screw assembly. h and pitch circle diameter D pw Calculate the helix angle ; Step B: Design the projection center line A”B”C”D of the return ball channel center line in the YOZ plane, so that it is composed of the straight line segment A”B”, the arc segment B”C” and the straight line segment C”D connected in sequence; Step C: Set the equation of line segment A”B” as z=-cot(α)·y, set the equation of line segment C”D” as z=b, set the radius of arc segment B”C” as r, the center of the circle as O”, and its coordinates as (y c” , z o” ); Step D: Based on the structural dimensions of the nut and the diameter of the steel ball, design the specific values ​​of b and r, and make them satisfy the geometric constraint relationship that the arc segment B”C” is tangent to both the straight line segment A”B” and the straight line segment C”D”.

[0016] Compared with the prior art, the beneficial effects of this application are as follows: (1) This application integrates the dustproof tongue and part of the return ball channel into the same dustproof and return ball integrated device. The device is respectively installed on both ends of the nut, and simultaneously realizes the two major functions of dustproof and steel ball reversal and return. Compared with the prior art, where the dustproof device and the return ball device are independent and installed separately, this application greatly reduces the number of parts, simplifies the structure of the nut end, and reduces the assembly difficulty and manufacturing cost.

[0017] (2) This application sets the dustproof tongue and part of the return ball channel on the same device. The phase relationship between the two is guaranteed by one machining process. The phase accuracy requirements of the original dustproof device are transferred to the return ball device. This allows one component to guarantee the phase accuracy of the original return ball device and dustproof device. Moreover, the positional accuracy of the dustproof tongue and return ball channel is guaranteed by one clamping process. This avoids the phase deviation caused by random assembly of the dustproof device in the traditional solution and significantly improves the accuracy consistency and stability of batch products. In addition, since the integrated dustproof and return ball device is fixed at both ends of the nut and the relative position between the dustproof tongue and the return ball channel is directly guaranteed by the machining accuracy, during assembly, the dustproof tongue will automatically be in the precise middle position of the screw thread raceway when the device is installed normally. There is no need to repeatedly adjust or randomly align the dustproof structure as in the prior art, which greatly improves the assembly efficiency and reliability.

[0018] (3) The dustproof tongue of this application is located in the middle of the first spiral raceway of the ball screw, and is fitted with a clearance rather than a traditional contact seal. When the ball screw pair is running at high speed and continuously, the dustproof tongue does not slide and rub against the surface of the ball screw raceway, thereby fundamentally avoiding the temperature rise caused by friction, meeting the industry's increasingly high requirements for the temperature rise of the ball screw pair during continuous operation, while extending the product life and improving the transmission accuracy.

[0019] (4) The second half of the ball return channel in this application corresponds to the first half of the ball return channel in the nut base wall. The two are combined to form a complete rotation channel. The rotation channel is smoothly connected to the ball return axial channel and the spiral raceway to form a complete ball return channel. When the steel ball rolls in the ball return channel, it runs smoothly, effectively reducing noise and vibration and improving transmission efficiency.

[0020] (5) The design method of this application decomposes the center line of the ball return channel into three segments, directly determines the slope of the inlet straight segment by using the helix angle α, and makes the values ​​of b and r satisfy the constraint condition that the arc segment and the two straight segments are tangent at the same time, thereby ensuring that the ball return channel is smooth and without sharp points, the steel ball moves smoothly, and realizes the rapid parametric design of ball screw pairs of different specifications. Attached Figure Description

[0021] Figure 1 This is a three-dimensional structural schematic diagram of the present invention, wherein the nut is in partial cross-sectional form to show its internal state.

[0022] Figure 2 This is an exploded view of the three-dimensional structure of the present invention.

[0023] Figure 3 This is a cross-sectional view of the present invention.

[0024] Figure 4 This is a three-dimensional structural diagram of the connection state of the nut and dustproof ball return integrated device of the present invention.

[0025] Figure 5 This is a cross-sectional view of the connection state of the nut and dustproof ball return integrated device of the present invention.

[0026] Figure 6 This is a three-dimensional structural diagram of the dustproof ball return integrated device of the present invention.

[0027] Figure 7 This is a three-dimensional structural diagram of the integrated dustproof ball return device from another perspective of the present invention.

[0028] Figure 8 This is a front view of the dustproof ball return integrated device of the present invention.

[0029] Figure 9 This is a cross-sectional view of the dustproof ball return integrated device of the present invention.

[0030] Figure 10 This is a schematic diagram of the center line of the ball return channel in the three-dimensional state of the present invention.

[0031] Figure 11 This is a schematic diagram of the center line of the ball return channel in the XOZ plane of this invention.

[0032] Figure 12 This is a schematic diagram of the center line of the overall return ball channel under the YOZ plane of this invention.

[0033] Figure 13 This is a partially enlarged schematic diagram of the center line of the return ball channel in the YOZ plane of this invention.

[0034] Figure 14 This is a three-dimensional structural diagram of the nut of the present invention.

[0035] Figure 15 This is a schematic diagram of the three-dimensional structure of the nut from another perspective of the present invention.

[0036] Figure 16 This is a cross-sectional view of the nut of the present invention.

[0037] In the diagram: 1. Lead screw; 11. First spiral raceway; 2. Nut; 21. Ball return section; 211. Mounting groove; 2111. First straight half-ball return channel; 2112. Arc half-ball return channel; 2113. Second straight half-ball return channel; 2114. First assembly groove; 2115. Second assembly groove; 212. Ball return axial channel; 22. Second spiral raceway; 3. Dustproof ball return integrated device; 31. Dustproof tongue; 32. Spiral ball stopper; 33. Straight section of the first half-ball return channel; 34. Arc reversing section of the half-ball return channel; 35. Ball return buffer section; 36. Ball return main body; 37. Dustproof main body ring; 38. Straight section of the second half-ball return channel; 4. Steel ball; 5. Center line of the ball return channel. Detailed Implementation

[0038] The present application will be further described below with reference to specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0039] In the description of this application, it should be noted that the terms "center", "lateral", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., which indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and should not be construed as limiting the specific protection scope of this application.

[0040] It should be noted that the terms "first," "second," etc., in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0041] The terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or device.

[0042] A preferred embodiment of this application, such as Figures 1 to 16 As shown, a dustproof ball screw assembly includes: The lead screw 1, as the core transmission component of the ball screw pair, has a first helical raceway 11 on its outer circumference and has a helix angle α.

[0043] Nut 2, Nut 2 is assembled on lead screw 1, such as Figures 14 to 16 As shown, it is provided with a ball return section 21 and a second spiral raceway 22. The second spiral raceway 22 is provided on the inner side wall of the nut 2 and corresponds to the first spiral raceway 11. The two form a complete spiral raceway. The ball return section 21 is provided in the base wall of the nut 2. It includes a ball return axial channel 212 and two first half ball return channels located at both ends of the ball return axial channel 212.

[0044] Nut 2 is fitted onto lead screw 1, and the second helical raceway 22 on its inner sidewall aligns with the first helical raceway 11 of lead screw 1 to form a complete helical raceway. The ball return section 21 is located inside the base wall of nut 2, including a ball return axial channel 212 and two first half-ball return channels at both ends, which are used to guide the steel ball 4 from the helical raceway into the return channel to realize the cyclic movement of the steel ball 4. In this embodiment, a part of the ball return channel is integrated into the base of nut 2 by machining, which has high precision and good rigidity, avoiding the loosening risk of traditional tube-type or external ball return devices. At the same time, the low surface roughness of the machined surface is conducive to the smooth operation of the steel ball 4.

[0045] To ensure that the second half-return ball channel of the dustproof ball return integrated device 3 is aligned with the first half-return ball channel on the nut 2, in this embodiment, as follows: Figures 15 to 16 As shown, the nut 2 has mounting grooves 211 at both ends. The mounting grooves 211 are formed with a first assembly groove 2114, a second assembly groove 2115, and a first half-return ball channel. The first half-return ball channel includes a first straight half-return ball channel 2111, an arc half-return ball channel 2112, and a second straight half-return ball channel 2113 connected in sequence. The first straight half-return ball channel 2111 is smoothly connected to the second spiral raceway 22, and the second straight half-return ball channel 2113 is smoothly connected to the return ball axial channel 212. When the dustproof return ball integrated device 3 is assembled with the nut 2, the return ball body part 36 is embedded in the first assembly groove 2114, and the return ball buffer part 35 is embedded in the second assembly groove 2115, so that the first straight half-return ball channel 2111, the arc half-return ball channel 2112, and the second straight half-return ball channel 2113 cooperate with the straight part 33 of the first half-return ball channel, the arc reversing part 34 of the half-return ball channel, and the straight part 38 of the second half-return ball channel to form a complete rotation channel.

[0046] The mounting groove 211 and the corresponding structure on the dustproof ball return integrated device 3 form an embedded fit, which can ensure the docking accuracy of the ball return channel without additional adjustment. At the same time, the machining accuracy of the mounting groove 211 is higher than the forming accuracy of the mold, ensuring the consistency of batch products.

[0047] It should be noted that the two mounting slots 211 at both ends of the nut 2 are 180° rotationally symmetrical with respect to the axial mid-section of the return ball axial channel 212. This design ensures that the phase of the return ball channel is consistent when the dustproof return ball integrated device 3 is installed at both ends of the nut 2. Moreover, during processing, only one set of processing programs is needed to complete the manufacturing of the mounting slots 211 at both ends. During assembly, the devices at both ends can be interchanged, reducing the types of parts. More importantly, during operation, the steel ball 4 is subjected to symmetrical forces when returning at both ends, avoiding additional bending moments.

[0048] The dustproof ball return integrated device 3 is respectively assembled at both ends of the nut 2. In this embodiment, the two are fixed by screws. The number of screws is determined according to the installation and load conditions. In this embodiment, both ends of the nut 2 are fixed to the dustproof ball return integrated device 3 by four screws. The dustproof ball return integrated device 3 is provided with a dustproof tongue 31 and a second half-ball return channel, such as... Figure 3 As shown, the dustproof tongue 31 is located in the middle of the first spiral raceway 11 and the two are fitted with a clearance, as... Figures 4 to 5 As shown, the second half of the ball return channel corresponds to the first half of the ball return channel, and the two form a complete ball return channel. The ball return axial channel 212 and the spiral raceway are all smoothly connected, thus forming a complete ball return channel.

[0049] This embodiment integrates the dustproof tongue 31 and a portion of the ball return channel into a single integrated dustproof and ball return device 3. This device is mounted on both ends of the nut 2, simultaneously achieving the two functions of dust prevention and ball return reversal. Compared to the prior art where the dustproof device and ball return device are independent and installed separately, this application significantly reduces the number of parts, simplifies the structure at the end of the nut 2, and reduces assembly difficulty and manufacturing costs. Furthermore, the phase relationship between the two is ensured by a single machining process, transferring the phase accuracy requirements of the original dustproof device to the ball return device. This allows one component to guarantee the phase accuracy of both the original ball return device and dustproof device, and a single clamping and machining process simultaneously ensures the phase accuracy of both the dustproof tongue 31 and the ball return device. The precise positioning of the channel avoids the phase deviation caused by random assembly of dustproof devices in traditional solutions, significantly improving the accuracy consistency and stability of batch products. Furthermore, since the integrated dustproof ball return device 3 is fixed at both ends of the nut 2, and the relative position between the dustproof tongue 31 and the ball return channel is directly guaranteed by machining precision, during assembly, simply installing the device normally will automatically place the dustproof tongue 31 in the precise middle position of the thread raceway of the lead screw 1. Unlike existing technologies, there is no need for repeated adjustments or random alignment of the dustproof structure, greatly improving assembly efficiency and reliability. Simultaneously, the integrated dustproof ball return device 3 is fixed to the nut 2 with screws, making disassembly and assembly convenient, facilitating maintenance and replacement. The number of screws can be adjusted according to the actual load, providing good adaptability.

[0050] Specifically, such as Figures 6 to 7 As shown, the integrated dustproof and ball return device 3 includes a dustproof main ring 37, a ball return main body 36, a spiral ball deflector 32, and a ball return buffer 35. The ball return main body 36 is fixedly disposed on one side of the dustproof main ring 37, the spiral ball deflector 32 is fixedly disposed between the dustproof main ring 37 and the ball return main body 36, and the ball return buffer 35 is fixedly disposed on the ball return main body 36. The dustproof tongue 31 is spirally protruding and is fixedly disposed on the inner side wall of the dustproof main ring 37 and is adapted to the first spiral raceway 11.

[0051] In this embodiment, the dustproof tongue 31 is located in the middle of the first helical raceway 11 of the lead screw 1, and a clearance fit is used between it and the first helical raceway 11, rather than a traditional contact seal. When the ball screw pair is running at high speed continuously, the dustproof tongue 31 does not slide and rub against the raceway surface of the lead screw 1, thereby fundamentally avoiding the temperature rise caused by friction. This meets the industry's increasingly high requirements for the temperature rise of the ball screw pair during continuous operation, while extending the product life and improving the transmission accuracy. It is especially suitable for high-speed operation.

[0052] Furthermore, the second half-return channel is formed on the return body 36 and the return buffer 35. The second half-return channel includes a first half-return channel straight section 33, a half-return channel arc reversing section 34, and a second half-return channel straight section 38 connected in sequence. The first half-return channel straight section 33 is located on the return body 36, and the half-return channel arc reversing section 34 and the second half-return channel straight section 38 are located on the return buffer 35.

[0053] It should be noted that the center line of the spiral ball deflector 32 and the center line of the dustproof tongue 31 are located on the same spiral line, and there is a phase relationship between the two.

[0054] In this embodiment, as Figures 8 to 9 As shown, the phase angle between the two is 180°, and the axial distance is... Of course, in other embodiments, the phase angle can be designed to other degrees, such as greater than 180°, which can be adjusted by those skilled in the art according to the actual parameters of the product.

[0055] By integrating the phase relationship between the dustproof tongue 31 and the spiral ball stopper 32 into the same device, the phase accuracy requirements of the original dustproof device are transferred to the ball return device. The relative positions of the two can be guaranteed in one processing, so that one component can guarantee the phase accuracy of the original ball return device and dustproof device. At the same time, the processing difficulty and cost are greatly reduced, the batch products have good accuracy consistency, and no adjustment is required during assembly.

[0056] like Figure 10 As shown, the center line 5 of the return channel of the second half of the ball return channel consists of three consecutive segments: a straight line segment AB, an arc segment BC, and a straight line segment CD.

[0057] like Figure 11 As shown, in the XOZ plane, the projected center lines A'B'C'D' of the return ball channel center line 5 satisfy the equation of a straight line: , in, Let z be the pitch circle diameter of the ball screw assembly. b is a constant, determined based on the structural dimensions of nut 2 and the diameter of steel ball 4.

[0058] like Figure 12 and Figure 13 As shown, in the YOZ plane, the projection center line A”B”C”D” of the return ball channel center line 5 is composed of three consecutive segments, namely the straight line segment A”B”, the circular arc segment B”C”, and the straight line segment C”D”. With A” as the origin, the line segment A”B” satisfies the following equation: z = -cot(α)·y Where α is the helix angle of the ball screw pair, which satisfies P h This is the lead of the ball screw pair; the straight line is consistent with the direction in which the steel ball 4 enters tangentially from the helical raceway, ensuring that the steel ball 4 smoothly enters the rotation channel with the same helix angle, avoiding impact and sudden acceleration at the connection, and reducing noise and wear.

[0059] Arc segment B”C” is an arc with radius r, and the center point of the arc is O”. The coordinates of O” are (y = r, r ... c” , z o” ), where z o” =br, then the arc segment B”C” satisfies the equation: (yy c” ) 2 +(zz o” ) 2 =r 2 ; The arc segment B”C” is the key part of the rotary channel to realize the direction change. It changes the movement of steel ball 4 from oblique to horizontal so that steel ball 4 can enter the return ball axial channel 212. The arc curve is smooth and the curvature is constant. The centripetal force on steel ball 4 during the direction change is stable, which is conducive to high-speed operation. By selecting an appropriate value of r, steel ball 4 can smoothly climb over the thread crest of lead screw 1. Usually, r is greater than 2 to 3 times the radius of steel ball 4 to avoid jamming.

[0060] Line segment C”D” satisfies the equation of the line: z=b; This segment connects with the return ball axial channel 212 of nut 2, guiding the steel ball 4 to return horizontally. The horizontal segment ensures that the steel ball 4 moves smoothly in the axial direction at the end of the second half of the return ball channel, and smoothly connects with the return ball axial channel 212 on nut 2.

[0061] like Figure 13 As shown, with A” as the origin and the coordinates of A” being (0, 0), the coordinates of all other points are: The coordinate of B is ( , ), The coordinate of C is ( b) The coordinate of D is ( b), of which , The coordinate of O is ( ,br) The H coordinate is ( , ), The coordinate of G is ( ,br).

[0062] Reference Figure 13 As shown, the arc segment B”C” is divided into two segments, namely the arc segment B”G” and the arc segment GC”; The circular arc segment B”G satisfies the equation: , The circular arc segment "GC" satisfies the following equation: ; Line segment A”B” satisfies the equation: .

[0063] By using the coordinates of the aforementioned feature points and the piecewise equations of the arc segments, the geometry of the centerline 5 of the return ball channel is accurately described, providing a direct mathematical basis for CNC machining. Engineers can input these equations into the software to automatically generate toolpaths and machine a return ball channel that conforms to the design. The piecewise expression of the arc segment equations avoids ambiguity at point G of the arc curve and ensures the single-valuedness of the curve.

[0064] Steel ball 4 is rolled and assembled in the return ball channel; when nut 2 moves relative to lead screw 1, steel ball 4 is adapted to move along the return ball channel.

[0065] This application also provides a method for designing the return channel of an integrated dustproof ball screw pair, comprising the following steps: Step A: Determine the lead P of the ball screw assembly. h and pitch circle diameter D pw Calculate the helix angle ; Step B: Design the projection center line A”B”C”D of the return ball channel center line 5 in the YOZ plane, so that it is composed of the straight line segment A”B”, the arc segment B”C and the straight line segment C”D connected in sequence; Step C: Set the equation of line segment A”B” as z=-cot(α)·y, set the equation of line segment C”D” as z=b, set the radius of arc segment B”C” as r, the center of the circle as O”, and its coordinates as (y c” , z o” ); Step D: Based on the structural dimensions of nut 2 and the diameter of steel ball 4, design the specific values ​​of b and r, and make them satisfy the geometric constraint relationship that the arc segment B”C” is tangent to both the straight line segment A”B” and the straight line segment C”D”.

[0066] It should be noted that in a purely geometric model, when there are only two infinitely long intersecting straight lines, there are indeed infinitely many circles tangent to both. However, in the actual engineering design of this application, the following additional constraints exist: First, the length of segment A”B” is fixed, which is determined by the length of the first straight half-return ball channel 2111 on nut 2, so point B” is a fixed point; second, the tangency condition: the arc must be tangent to segment A”B” at point B and tangent to C”D” simultaneously; finally, the value of b is a constant, determined according to the structural dimensions of nut 2 and the diameter of steel ball 4. In actual design, engineers usually first select b based on engineering constraints such as the end wall thickness of nut 2 and the climbing height of steel ball 4, and then calculate the corresponding r through the tangency condition. Of course, in other cases, engineers will determine b and r simultaneously through numerical optimization.

[0067] The basic principles, main features, and advantages of this application have been described above. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely the principles of this application. Various changes and modifications can be made to this application without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection claimed by this application is defined by the appended claims and their equivalents.

Claims

1. A dustproof ball screw assembly with integrated ball return mechanism, characterized in that, include: The lead screw has a first helical raceway on its outer circumferential surface; The nut is assembled on the lead screw and has a ball return section and a second helical raceway. The second helical raceway is located on the inner wall of the nut and corresponds to the first helical raceway. The two form a complete helical raceway. The ball return section is located inside the base wall of the nut and includes a ball return axial channel and two first half ball return channels located at both ends of the ball return axial channel. The dustproof ball return integrated device is assembled on both ends of the nut. The dustproof ball return integrated device is provided with a dustproof tongue and a second half ball return channel. The dustproof tongue is located in the middle of the first helical raceway and the two are fitted with a clearance. The second half ball return channel corresponds to the first half ball return channel. The two form a complete rotation channel. The rotation channel is smoothly connected to the ball return axial channel and the helical raceway, thus forming a complete ball return channel. The steel ball is rolled within the return ball channel; when the nut moves relative to the lead screw, the steel ball is adapted to move along the return ball channel. The integrated dustproof ball return device includes a dustproof main ring, a ball return main body, a spiral ball stopper, and a ball return buffer. The ball return main body is fixedly installed on one side of the dustproof main ring, the spiral ball stopper is fixedly installed between the dustproof main ring and the ball return main body, and the ball return buffer is fixedly installed on the ball return main body. The dustproof tongue is spirally protruding and is fixedly installed on the inner wall of the dustproof main ring, located in the middle of the first spiral raceway on the lead screw, and is clearance-fitted with the first spiral raceway. The center line of the second half of the ball return channel consists of three consecutive segments: a straight line segment AB, an arc segment BC, and a straight line segment CD. In the XOZ plane, the projected center lines A'B'C'D' of the return ball channel centerline satisfy the equation of a straight line: ， in, Let z be the pitch circle diameter of the ball screw assembly. b is a constant, determined based on the nut's structural dimensions and the diameter of the steel ball; In the YOZ plane, the projected center line A”B”C”D” of the return ball channel center line consists of three consecutive segments: straight line segment A”B”, circular arc segment B”C”, and straight line segment C”D”. With A” as the origin, the line segment A”B” satisfies the following equation: z = -cot(α)·y Where α is the helix angle of the ball screw pair, which satisfies P h The lead of the ball screw assembly; Arc segment B”C” is an arc with radius r, and the center point of the arc is O”. The coordinates of O” are (y = r, r ... c” , z o” ), where z o” =br, then the arc segment B”C” satisfies the equation: (y-y c” ) 2 +(z-z o” ) 2 =r 2 ; Line segment C”D” satisfies the equation of the line: z=b; The arc segment B”C” is divided into two segments, namely the arc segment B”G” and the arc segment GC”; Wherein, the coordinate of G is ( , z o” ); The circular arc segment B”G satisfies the equation: ， The circular arc segment "GC" satisfies the following equation: 。 2. The dustproof ball screw assembly as described in claim 1, characterized in that, The second half-return channel is formed on the return ball body and the return ball buffer. The second half-return channel includes a straight section of the first half-return channel, a circular arc reversal section of the half-return channel, and a straight section of the second half-return channel that are connected in one step. The straight section of the first half-return channel is located on the return ball body, and the circular arc reversal section of the half-return channel and the straight section of the second half-return channel are located on the return ball buffer.

3. The dustproof ball screw assembly as described in claim 1, characterized in that, The centerline of the spiral ball stopper and the centerline of the dustproof tongue are on the same spiral line.

4. The dustproof ball screw assembly as described in claim 2, characterized in that, The nut has mounting grooves at both ends, and the mounting grooves contain a first assembly groove, a second assembly groove, and a first half-return ball channel. The first half-return ball channel includes a first straight half-return ball channel, an arc half-return ball channel, and a second straight half-return ball channel connected in sequence. The first straight half-return ball channel is smoothly connected to the second helical raceway, and the second straight half-return ball channel is smoothly connected to the axial return ball channel. When the dustproof return ball integrated device is assembled with the nut, the return ball body is embedded in the first assembly groove, and the return ball buffer is embedded in the second assembly groove, so that the first straight half-return ball channel, the arc half-return ball channel, and the second straight half-return ball channel cooperate with the straight part of the first half-return ball channel, the arc reversing part of the half-return ball channel, and the straight part of the second half-return ball channel to form a complete rotation channel.

5. The dustproof ball screw assembly as described in claim 4, characterized in that, The two mounting slots at both ends of the nut are symmetrically distributed at 180° relative to the axial mid-section of the return ball axial channel.

6. A method for designing the return ball channel of an integrated dustproof ball screw assembly as described in any one of claims 1 to 5, characterized in that, It includes the following steps: Step A: Determine the lead P of the ball screw assembly. h and pitch circle diameter D pw Calculate the helix angle ; Step B: Design the projection center line A”B”C”D of the return ball channel center line in the YOZ plane, so that it is composed of the straight line segment A”B”, the arc segment B”C” and the straight line segment C”D connected in sequence; Step C: Set the equation of line segment A”B” as z=-cot(α)·y, set the equation of line segment C”D” as z=b, set the radius of arc segment B”C” as r, the center of the circle as O”, and its coordinates as (y c” , z o” ); Step D: Based on the structural dimensions of the nut and the diameter of the steel ball, design the specific values ​​of b and r, and ensure that they satisfy the geometric constraint that the arc segment B”C” is tangent to both the straight segments A”B” and C”D”.

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