Based on the anti-deviation positioning device for thin-walled workpieces of CNC machine tools

Abstract

This invention relates to the field of positioning technology for thin-walled workpieces, and discloses a positioning device for preventing offset of thin-walled workpieces based on CNC machine tools. It aims to solve the technical problems of easy deformation during positioning of thin-walled workpieces and poor adaptability of traditional clamping blocks. The device includes a CNC machine tool body, a rotating chuck, an adjustment drive assembly, a push rod assembly, and a tensioning positioning assembly. A frustum-shaped push block converts rotational motion into linear motion via a screw and nut mechanism. This, in conjunction with a limiting assembly, drives the push rod assembly to synchronously and uniformly extend and retract radially, causing a spring steel sheet with a pre-positioned section to achieve curvature self-adaptation. The pre-positioned section is a sliding compensation arc surface section, adapting to thin-walled pipes of different diameters while maintaining surface contact. The device has two sets of staggered tensioning positioning rings, forming a full-circumferential, gapless support for the inner wall of the pipe. This device avoids stress concentration problems caused by line contact, effectively preventing deformation of thin-walled pipes, balancing positioning firmness and deformation prevention requirements, and significantly improving the processing qualification rate and production efficiency of thin-walled pipes.

Description

Technical Field

[0001] This invention relates to the field of positioning technology for thin-walled workpieces, and more particularly to a positioning device for preventing offset of thin-walled workpieces based on CNC machine tools. Background Technology

[0002] The thin-walled positioning device for CNC machine tools is a specialized component and functional accessory adapted to various CNC machine tool processing scenarios. It is a core supporting positioning component when CNC machine tools process thin-walled tubes. It is specifically designed to solve the processing pain point of thin-walled tubes, which are prone to plastic deformation due to uneven force during positioning due to their thin wall thickness and low structural rigidity. The key points of its design and use always revolve around the uniform distribution of support force. As an important supporting accessory for CNC machine tools, it needs to avoid the processing deformation problem of thin-walled tubes from the positioning stage. It is a key supporting component to ensure the processing accuracy of thin-walled tubes on CNC machine tools and improve the workpiece qualification rate.

[0003] In existing technologies, when using internal expansion to support and position pipe fittings, multiple arc-shaped clamps extend radially outward to press against the inner wall of the fitting to achieve expansion and positioning. While this design attempts to adapt the curved surface structure of the arc-shaped clamps to the curved inner wall of the fitting to achieve uniform surface contact support, it is limited by the fixed curvature of the arc-shaped clamps. It cannot adaptively adjust to the actual curvature of the inner wall of fittings with different diameters. Therefore, when positioning fittings of different diameters, it is difficult to achieve an ideal, complete fit between the arc-shaped clamps and the inner wall of the fitting. The contact between the clamping block and the inner wall eventually becomes a line contact, which prevents the tightening force from being evenly distributed across the pipe wall. Instead, it concentrates at the contact line between the clamping block and the inner wall. Thin-walled pipes, due to their thin wall thickness and low structural rigidity, have a weak ability to resist local stress. This stress concentration caused by line contact makes thin-walled pipes prone to local elastic deformation or even plastic deformation during the tightening and positioning stage. This not only damages the original shape and position accuracy of the pipe but also further amplifies the deformation error during subsequent processing, seriously affecting the processing accuracy of the pipe and even causing the workpiece to be scrapped. Summary of the Invention

[0004] The technical problem to be solved by the present invention is that when the existing technology uses the internal expansion method to support and position the pipe fittings, the curvature of the arc-shaped clamp is fixed. When adapting to pipe fittings of different diameters, it cannot achieve full fit with the inner wall, only forming line contact and causing stress concentration. This can easily lead to deformation of thin-walled pipe fittings, thereby damaging their shape and position accuracy, affecting processing accuracy, or even causing the workpiece to be scrapped. To this end, we propose a thin-walled workpiece anti-offset positioning device based on CNC machine tools.

[0005] To achieve the above objectives, this application adopts the following technical solution: a CNC machine tool thin-walled workpiece anti-offset positioning device, comprising: a CNC machine tool body, a rotating chuck installed inside the CNC machine tool body, an adjustment drive assembly coaxially installed on the side of the rotating chuck, the adjustment drive assembly including a push block, the push block being shaped like a frustum, and the push block including a large end and a small end, a drive groove being formed on the outer wall of the push block, a push rod assembly being provided outside the push block, a tensioning positioning assembly being supported at the end of the push rod assembly away from the push block, the tensioning positioning assembly including a spring steel sheet, the spring steel sheet including an arc surface segment and preparatory segments integrally provided at both ends of the arc surface segment, and a thin-walled tube body being sleeved on the outside of the tensioning positioning assembly;

[0006] When the push block moves forward, its large end approaches the push rod assembly, which in turn pushes the expansion and positioning assembly outward to enlarge the diameter of the arc segment, allowing the outer wall of the arc segment to adhere to the inner wall of the thin-walled pipe body for expansion and positioning. When the push block moves backward, its small end approaches the push rod assembly, which in turn pulls the expansion and positioning assembly inward to reduce the diameter of the arc segment. By adjusting the diameter of the arc segment, the positioning device can adapt to positioning thin-walled pipe bodies with different diameters, while maintaining surface contact during positioning.

[0007] Preferably, the push block has a through hole coaxially formed inside, a drive rod passes through the through hole, and a drive motor is installed at the end of the drive rod. The drive motor is located inside the rotating chuck.

[0008] Preferably, the outer wall of the drive rod is provided with a lead screw section, and the lead screw section passes through a through hole. A ball nut is sleeved on the outside of the lead screw section, and the ball nut is fixedly connected to the inside of the push block.

[0009] Preferably, the driving grooves are arranged in a ring array about the outer wall of the push block.

[0010] Preferably, the push rod assembly includes a push rod, one end of which is fixedly connected to a first slider, and the first slider is slidably connected inside the drive groove, and the other end of the push rod is fixedly connected to a second slider.

[0011] Preferably, the push rod assembly further includes a pull-back rod and a positioning rod. One end of the pull-back rod is slidably connected to the drive inclined groove, and the other end of the pull-back rod is slidably connected to the preparatory section. The length of the pull-back rod is shorter than that of the push rod. One end of the positioning rod is slidably connected to the drive inclined groove, and the other end of the positioning rod is fixedly connected to the arc surface section.

[0012] Preferably, a pressure sensor is installed on the outer wall of the spring steel sheet, and a pulling groove is fixedly connected to the inner wall of the spring steel sheet, with the second slider slidably connected inside the pulling groove.

[0013] Preferably, the length of the pull slide is consistent with the length of the spring steel sheet, and the end of the pull slide is detachably connected to a sealing block by screws.

[0014] Preferably, two sets of the tensioning and positioning components are symmetrically arranged on both sides of the push rod assembly, and the two sets of tensioning and positioning components together form a tensioning and positioning ring, wherein the preparatory sections of the two sets of tensioning and positioning components are staggered along the circumferential direction.

[0015] Preferably, a limiting component is provided on the back of the push rod assembly. The limiting component includes a fixed plate, and the fixed plate is fixedly connected to the rotating chuck. The fixed plate is provided with a fixed rod in a circular array on its side, and a slide cylinder is fixedly connected to the end of the fixed rod.

[0016] The technical effects and advantages of this invention are as follows:

[0017] This invention replaces the traditional fixed-curvature arc-shaped clamping block with a spring steel sheet-type expansion and contraction structure. A frustum-shaped pusher block, in conjunction with a limiting component, drives the push rod assembly to achieve synchronous and uniform radial expansion and contraction. This causes the arc-shaped surface segment to complete adaptive curvature adjustment, and the pre-section can slide and compensate to the arc-shaped surface segment as the curvature changes. This allows for precise matching of the inner wall curvature of thin-walled pipe fittings of different diameters. It achieves comprehensive and tight surface contact expansion and contraction without replacing the clamping block, completely avoiding the localized stress concentration problem caused by traditional line contact. This effectively prevents thin-walled pipe fittings from developing elasticity or plasticity due to uneven stress. The device achieves deformation while simultaneously ensuring the robustness of the expansion and positioning and preventing deformation. It also incorporates two sets of staggered spring steel expansion and positioning rings, with the arc-shaped section of the latter set precisely corresponding to the gap area of ​​the former set. This creates a continuous, gapless, full-circumferential surface contact support for the inner wall of the pipe fitting, eliminating weak support areas in single-set structures. This significantly improves the centering accuracy and coaxiality of the pipe fitting, enhances the overall structural rigidity after positioning, effectively guarantees the dimensional and geometric tolerances of the thin-walled pipe fitting, and significantly improves the processing qualification rate and production efficiency of the thin-walled pipe fitting. Attached Figure Description

[0018] The disclosure of this invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention. In the drawings, the same reference numerals are used to refer to the same parts:

[0019] Figure 1 This is a three-dimensional structural diagram of the entire invention;

[0020] Figure 2This is a three-dimensional structural diagram of the positioning state of the thin-walled tube body according to the present invention;

[0021] Figure 3 This is a three-dimensional structural diagram of the pushing block and the expansion positioning component of the present invention;

[0022] Figure 4 This is a three-dimensional structural diagram of the expansion and positioning component of the present invention;

[0023] Figure 5 This is a three-dimensional structural diagram of the push rod assembly and the pull slide section of the present invention;

[0024] Figure 6 This is a three-dimensional structural diagram of the limiting component and push rod component of the present invention;

[0025] Figure 7 This is a three-dimensional structural diagram of the push rod assembly of the present invention;

[0026] Figure 8 This is a schematic diagram of the structure of the drive component part of the present invention, showing the split state of the push block.

[0027] Legend: 1. CNC machine tool body; 2. Rotating chuck; 3. Adjustment drive assembly; 4. Push rod assembly; 5. Expansion and positioning assembly; 6. Limiting assembly; 7. Thin-walled pipe body; 301. Drive motor; 302. Drive rod; 303. Lead screw section; 304. Push block; 305. Through hole; 306. Ball nut; 307. Drive slant groove; 401. Push rod; 402. First slider; 403. Second slider; 404. Pull-back rod; 405. Positioning rod; 501. Arc surface section; 502. Preparatory section; 503. Pulling sluice; 504. Sealing block; 505. Pressure sensor; 601. Fixed plate; 602. Fixed rod; 603. Slide cylinder. Detailed Implementation

[0028] It is readily understood that, based on the technical solution of this invention, those skilled in the art can propose various interchangeable structural methods and implementations without altering the essential spirit of the invention. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative examples of the technical solution of this invention and should not be considered as the entirety of the invention or as limitations or restrictions on the technical solution of this invention.

[0029] Reference Figure 2 As shown, the present invention provides a technical solution: a positioning device for preventing offset of thin-walled workpieces based on CNC machine tools, comprising: a CNC machine tool body 1, a rotating chuck 2 installed inside the CNC machine tool body 1, the rotating chuck 2 being used to drive the positioning device and the workpiece to rotate and complete the machining.

[0030] Thin-walled pipes, due to their thin walls, low overall structural rigidity, and inherently weak resistance to local stress and deformation, face a critical technical challenge in controlling clamping force during the support and positioning stage of processing. The clamping force is crucial for ensuring the pipe's fixed position during machining. Insufficient clamping force cannot provide stable positioning constraints, making the pipe prone to shifting or deviating during subsequent cutting and milling processes. This can even lead to vibration and chatter, compromising positioning accuracy, causing dimensional deviations and exceeding form and position tolerances, and affecting surface quality. Conversely, increasing the clamping force to ensure positioning stability can create localized stress concentrations at the pipe's contact points, exceeding the thin-walled pipe's deformation resistance threshold. This can easily trigger elastic or even plastic deformation, compromising its original form and position accuracy. Furthermore, errors caused by such deformation are amplified during subsequent processing, ultimately resulting in substandard workpiece machining accuracy and, in severe cases, scrapping the entire workpiece.

[0031] In existing technologies, when using internal expansion to support and position pipe fittings, the mainstream approach involves multiple sets of arc-shaped clamps extending radially outward to press against the inner wall of the pipe fitting for expansion and fixation. The initial intention of this design was to rely on the curved surface structure of the arc-shaped clamps to adapt to the curved inner wall of the pipe fitting, thereby achieving surface contact expansion support and evenly distributing the expansion force across the pipe wall. However, in practical applications, the curvature of these arc-shaped clamps is fixed and cannot be adaptively adjusted according to the actual curvature of the inner wall of pipe fittings of different diameters. Replacing arc-shaped clamps with corresponding curvatures one by one to accommodate different pipe sizes is not only cumbersome but also increases equipment changeover time, reduces overall production efficiency, and frequent replacements can easily lead to… Assembly errors affect the coaxiality and tension consistency of the clamping blocks. If the clamping blocks are not replaced to simplify operation, when the curvature of the inner wall of the pipe fitting does not match the curvature of the arc-shaped clamping block, the two cannot achieve ideal surface contact and can only form line contact. This causes the tensioning force to be concentrated at the contact line between the clamping block and the inner wall, making it impossible to achieve uniform force distribution. For pipe fittings with thin walls and low structural rigidity, this stress concentration problem caused by line contact can easily lead to local deformation of the pipe fitting, destroying its original shape and position accuracy and creating potential accuracy hazards for subsequent processing. In order to solve the above technical problems and achieve effective surface contact fixation of the tensioning positioning mechanism for thin-walled pipe fittings of different diameters, this application makes the following improvements:

[0032] Please see Figure 1 and Figure 8As shown, an adjustment drive assembly 3 is coaxially mounted on the side of the rotating chuck 2. The adjustment drive assembly 3 includes a push block 304, which is shaped like a frustum and includes a large end and a small end. A through hole 305 is coaxially opened inside the push block 304. A drive rod 302 passes through the through hole 305, and a drive motor 301 is installed at the end of the drive rod 302. The drive motor 301 is located inside the rotating chuck 2. A lead screw section 303 is opened on the outer wall of the drive rod 302 and passes through the through hole 305. A ball nut 306 is sleeved on the outside of the lead screw section 303 and is fixedly connected to the inside of the push block 304. A drive groove 307 is opened on the outside of the push block 304 and is arranged in a ring array about the outer wall of the push block 304.

[0033] The drive motor 301 drives the drive rod 302 and the lead screw section 303 to rotate. While the lead screw section 303 is rotating, the rotational motion is converted into the linear motion of the push block 304 through the ball nut 306, thereby causing the push block 304 to move forward or backward.

[0034] Please see Figure 3 and Figure 7 As shown, a push rod assembly 4 is provided on the outside of the push block 304. The push rod assembly 4 includes a push rod 401. One end of the push rod 401 is fixedly connected to a first slider 402. The bottom surface of the first slider 402 is inclined, and the first slider 402 is slidably connected to the inside of the drive inclined groove 307.

[0035] Please see Figure 5 As shown, the push rod assembly 4 also includes a pull-back rod 404 and a positioning rod 405. One end of the pull-back rod 404 is slidably connected to the drive inclined groove 307, and the other end of the pull-back rod 404 is slidably connected to the preparatory section 502. The length of the pull-back rod 404 is shorter than that of the push rod 401, and the lengths of the pull-back rods 404 corresponding to the preparatory sections 502 in the expansion positioning assemblies 5 on both sides of the push block 304 are also inconsistent, so that the preparatory sections 502 in the expansion positioning assemblies 5 on both sides can be staggered. One end of the positioning rod 405 is slidably connected to the drive inclined groove 307, and the other end of the positioning rod 405 is fixedly connected to the arc surface section 501.

[0036] Please see Figure 6As shown, a limiting component 6 is provided on the back of the push rod assembly 4. The limiting component 6 includes a fixed plate 601, and the fixed plate 601 is fixedly connected to the rotating chuck 2. Fixed rods 602 are arranged in a ring array on the side of the fixed plate 601, and a slide cylinder 603 is fixedly connected to the end of the fixed rod 602. The limiting component 6 is used to limit the push rod assembly 4, so that the push rod assembly 4 cannot move back and forth. However, each set of slide cylinders 603 is slidably connected to the outside of the push rod 401, the pull-back rod 404 and the positioning rod 405, so that the push rod assembly 4 can slide radially inward and outward.

[0037] When the push block 304 is pushed forward, the push rod assembly 4 cannot move forward together due to the restriction of the limit assembly 6. The large end of the push block 304 gradually approaches and radially supports the push rod assembly 4, pushing the push rod assembly 4 outward. When the drive motor 301 reverses and the push block 304 moves backward, the small end of the push block 304 approaches the push rod assembly 4 and pulls the push rod assembly 4 inward.

[0038] Please see Figure 4 and Figure 5 As shown, the end of the push rod assembly 4 furthest from the push block 304 is supported by a tensioning and positioning assembly 5. Two sets of tensioning and positioning assemblies 5 are symmetrically arranged on both sides of the push rod assembly 4, and the two sets together form a tensioning and positioning ring. The preparatory sections 502 in the two sets of tensioning and positioning assemblies 5 are staggered circumferentially. Each tensioning and positioning assembly 5 includes a spring steel sheet, which includes an arc-shaped section 501 and preparatory sections 502 integrally disposed at both ends of the arc-shaped section 501. A pulling groove 503 is fixedly connected to the inner wall of the spring steel sheet. The length of the pulling groove 503 is consistent with the length of the spring steel sheet, and the pulling groove 503 can bend and deform together with the spring steel sheet. The other end of the push rod 401 is fixedly connected to the second slider 403, which is slidably connected inside the pull groove 503. The push rods 401 and the positioning rods 405 are of the same length, supporting the spring steel sheet into an arc shape to form an arc surface segment 501. The pull-back rod 404 is slightly shorter and pulls the spring steel sheets at both ends inward to form a preparatory segment 502. The lengths of the arc surface segment 501 and the preparatory segment 502 are not fixed. The preparatory segment 502 is a reserve part of the arc surface segment 501. When the curvature of the arc surface segment 501 expands, part of the preparatory segment 502 slides to the push rod 401, which can supplement the arc-shaped structure formed by the arc surface segment 501.

[0039] Please see Figure 4 As shown, a sealing block 504 is detachably connected to the end of the pull slide 503 by screws. When the spring steel sheet or the pull slide 503 is unable to be molded smoothly due to material fatigue and wear after repeated operation, the sealing block 504 can be removed to allow the second slider 403 to slide out from the end of the pull slide 503, and then the spring steel sheet and the pull slide 503 can be removed and replaced.

[0040] When the push block 304 moves forward, the large end of the push block 304 approaches the push rod assembly 4, and the push rod assembly 4 pushes the expansion positioning assembly 5 outward to expand the diameter of the arc surface section 501, so that the outer wall of the arc surface section 501 is in contact with the inner wall of the thin-walled pipe body 7, and the thin-walled pipe body 7 is expanded and positioned. When the push block 304 moves backward, the small end of the push block 304 approaches the push rod assembly 4, and the push rod assembly 4 pulls the expansion positioning assembly 5 inward to reduce the diameter of the arc surface section 501. The expansion positioning assembly 5 is fitted with the thin-walled pipe body 7. By adjusting the diameter of the arc surface section 501, the positioning device can adapt to positioning thin-walled pipe bodies 7 with different diameters, and always maintains surface contact during positioning.

[0041] Please see Figure 3 As shown, a pressure sensor 505 is installed on the outer wall of the spring steel sheet, and the outer walls of the spring steel sheet and the pressure sensor 505 are wrapped together with a layer of anti-slip silicone pad to increase the friction between the spring steel sheet and the inner wall of the thin-walled pipe body 7, and to ensure the stability of its positioning support.

[0042] By replacing the traditional fixed-curvature arc-shaped clamp with a spring steel sheet capable of plastic deformation, and adjusting the drive assembly 3 to drive the push rod assembly 4 to perform radial contraction or expansion, the external spring steel sheet achieves adaptive curvature adjustment. This design fundamentally solves the core technical pain point of traditional internal expansion positioning structures. The spring steel sheet can flexibly change its curvature with the radial movement of the push rod assembly 4, accurately matching the actual inner wall curvature of thin-walled pipe fittings of different diameters. This eliminates the need to replace the internal expansion clamp for each different pipe size, completely standardizing the design. It avoids the problems of cumbersome parts replacement and time-consuming model changeover in traditional solutions, and greatly improves the production changeover efficiency and positioning consistency of the equipment. At the same time, the spring steel sheet with adaptive curvature adjustment can achieve close and comprehensive surface contact with the inner wall of thin-walled pipe fittings of different diameters, replacing the line contact form of the traditional solution. This allows the tensioning force to be distributed more evenly on the inner wall of the thin-walled pipe fitting body 7, fundamentally eliminating the problem of local stress concentration, effectively avoiding elastic or plastic deformation of thin-walled pipe fittings caused by uneven force, and ensuring the original positioning accuracy of the pipe fittings.

[0043] Furthermore, the linear pushing method of the frustum-shaped pusher block 304 can achieve the synchronicity and uniformity of the radial expansion or contraction of the pusher assembly 4, thereby ensuring the coaxiality and fit of the overall expansion of the spring steel sheet. This makes the internal expansion and positioning of the thin-walled pipe more stable, providing sufficient expansion support force to prevent the pipe from shifting or deviating during processing. It also achieves flexible force distribution through the plastic fit of the steel sheet, adapting to the low stiffness and easily deformable material characteristics of thin-walled pipes, and taking into account both the firmness of positioning and the need for anti-deformation. In addition, the overall operation of this structure is simple. The forward and backward pushing of the pusher block 304 can be easily and precisely controlled through the lead screw section 303 and the ball nut 306. The expansion force can be flexibly adjusted according to the thin-walled pipes with different wall thicknesses and diameters. The equipment has strong versatility and can also reduce the inventory and maintenance costs of special clamping blocks, adapting to the needs of large-scale, multi-specification thin-walled pipe processing and production.

[0044] Since the radial adjustment of the arc section 501 is required, a certain reserve section 502 needs to be reserved to prevent the expansion and positioning assembly 5 from forming a complete annular structure to provide expansion and support to the inner wall of the thin-walled pipe body 7. To solve the above problems, this application makes the following improvements:

[0045] Please see Figure 1 As shown, the expansion positioning rings composed of the expansion positioning assembly 5 are arranged in two sets around the outside of the adjustment drive assembly 3. The arc support surface formed by the arc segment 501 in the latter expansion positioning ring precisely corresponds to the gap area of ​​the former set. The two sets of mechanisms work together to form a continuous, gapless surface contact support for the inner wall of the thin-walled pipe body 7 in the entire circumference, allowing the expansion force to evenly cover every area of ​​the pipe wall in the circumference, completely eliminating the force gap and weak support problem at the gap of a single set of mechanisms, and avoiding the micro-deformation of the thin-walled pipe due to local lack of support during expansion or processing; at the same time, the continuous surface contact in the entire circumference... This significantly improves the centering accuracy and coaxiality of the pipe fittings, allowing thin-walled pipe fittings to form an integrated support constraint after positioning. This enhances the structural rigidity of the pipe fittings after positioning, effectively reducing swaying, movement, and processing vibration caused by the lack of local support during processing, and ensuring the stability of positioning. For thin-walled pipe fittings with weak deformation resistance, the uniform continuous surface contact in the entire circumference can also minimize the possibility of local stress concentration. From the perspective of support layout, this further ensures the original shape and position accuracy of the pipe fittings, making it easier to control the dimensional and shape and position tolerances in subsequent processing, and effectively improving the processing qualification rate of thin-walled pipe fittings.

[0046] Working principle: The thin-walled tube body 7 to be processed is placed on the outside of the expansion and positioning assembly 5. Then, the drive motor 301 is started. The output end of the drive motor 301 drives the drive rod 302 and the lead screw section 303 to rotate. While the lead screw section 303 is rotating, the ball nut 306 pushes the push block 304 forward. The push rod assembly 4 is restrained by the limiting assembly 6 and cannot move forward or backward. When the push block 304 moves forward, the large end of the push block 304 gradually pushes against the bottom end of the push rod assembly 4. Each group of first sliders 402 gradually slides along the drive inclined groove 307 towards the large end of the push block 304. As the radius of the push block 304 corresponding to the push rod assembly 4 gradually increases, the push rod assembly 4 is gradually pushed outward, and the outward extension is consistent.

[0047] As the push rod assembly 4 gradually pushes outward, its outer end also pushes the expansion and positioning assembly 5 outward, expanding the expansion and positioning assembly 5. Since the push rod 401 and the positioning rod 405 are of the same length, they correspond to the arc section 501 of the spring steel sheet, shaping the arc section 501 into an arc shape. The pull-back rods 404 at both ends of the expansion and positioning assembly 5 are slightly shorter, stretching the preparatory section 502 inward to prevent it from tilting outward. As the push rod assembly 4 gradually extends outward, part of the preparatory section 502 can slide to compensate to the end of the push rod 401, compensating for the arc-shaped support piece formed by the arc section 501, until the outer wall of the arc section 501 contacts the inner wall of the thin-walled pipe body 7 and expands and positions the thin-walled pipe body 7. After the pressure value identified by the pressure sensor 505 reaches the specified threshold, the drive motor 301 stops rotating; then the chuck 2 rotates to drive the entire positioning device and the expanded and positioned thin-walled pipe body 7 to rotate together for machining.

[0048] The technical scope of this invention is not limited to the content described above. Those skilled in the art can make various modifications and variations to the above embodiments without departing from the technical concept of this invention, and all such modifications and variations should fall within the protection scope of this invention.

Claims

1. A positioning device for preventing offset of thin-walled workpieces on CNC machine tools, characterized in that, The system includes a CNC machine tool body, inside which a rotary chuck is installed. An adjustment drive assembly is coaxially mounted on the side of the rotary chuck. The adjustment drive assembly includes a push block, which is shaped like a frustum and includes a large end and a small end. A drive groove is formed on the outer wall of the push block. A push rod assembly is provided on the outside of the push block. A tensioning and positioning assembly is supported at the end of the push rod assembly away from the push block. The tensioning and positioning assembly includes a spring steel sheet, which includes an arc-shaped section and pre-sections integrally set at both ends of the arc-shaped section. A thin-walled tubular body is sleeved on the outside of the tensioning and positioning assembly. When the push block moves forward, its large end approaches the push rod assembly, which in turn pushes the expansion and positioning assembly outward to widen the arc section's diameter, allowing the outer wall of the arc section to contact the inner wall of the thin-walled pipe body for expansion and positioning. When the push block moves backward, its small end approaches the push rod assembly, which in turn pulls the expansion and positioning assembly inward to narrow the arc section's diameter. By adjusting the arc section's diameter, the positioning device can adapt to positioning thin-walled pipe bodies with different diameters, while maintaining surface contact during positioning. The push rod assembly includes a push rod, one end of which is fixedly connected to a first slider, and the first slider is slidably connected to the inside of the drive groove; the other end of the push rod is fixedly connected to a second slider. The push rod assembly also includes a pull-back rod and a positioning rod. One end of the pull-back rod is slidably connected to the drive inclined groove, and the other end of the pull-back rod is slidably connected to the preparatory section. The length of the pull-back rod is shorter than that of the push rod. One end of the positioning rod is slidably connected to the drive inclined groove, and the other end of the positioning rod is fixedly connected to the arc surface section. A pressure sensor is installed on the outer wall of the spring steel sheet, and a pull groove is fixedly connected to the inner wall of the spring steel sheet. The second slider is slidably connected inside the pull groove.

2. The anti-deviation positioning device for thin-walled workpieces based on CNC machine tools according to claim 1, characterized in that: The push block has a through hole coaxially inside, and a drive rod passes through the through hole. A drive motor is installed at the end of the drive rod, and the drive motor is located inside the rotating chuck.

3. The anti-deviation positioning device for thin-walled workpieces based on CNC machine tools according to claim 2, characterized in that: The outer wall of the drive rod is provided with a lead screw section, and the lead screw section passes through a through hole. A ball nut is sleeved on the outside of the lead screw section, and the ball nut is fixedly connected to the inside of the push block.

4. The anti-deviation positioning device for thin-walled workpieces on CNC machine tools according to claim 1, characterized in that: The drive spurs are arranged in a ring array about the outer wall of the push block.

5. The anti-deviation positioning device for thin-walled workpieces on CNC machine tools according to claim 1, characterized in that: The length of the pull slide is the same as the length of the spring steel sheet, and the end of the pull slide is detachably connected to a sealing block by screws.

6. The anti-deviation positioning device for thin-walled workpieces based on CNC machine tools according to claim 1, characterized in that: The tensioning and positioning components are arranged symmetrically on both sides of the push rod assembly in two sets, and the two sets of tensioning and positioning components together form a tensioning and positioning ring, wherein the preparatory sections of the two sets of tensioning and positioning components are staggered along the circumferential direction.

7. The anti-deviation positioning device for thin-walled workpieces based on CNC machine tools according to claim 1, characterized in that: The back of the push rod assembly is provided with a limiting component, which includes a fixed plate and is fixedly connected to a rotating chuck. The fixed plate is provided with a fixed rod in a circular array on its side, and a slide cylinder is fixedly connected to the end of the fixed rod.

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