Self-adaptive clamp for finish machining of outer circle of variable-cross-section thin-wall part

Abstract

The invention discloses a self-adaptive clamp for finish machining of an outer circle of a variable-cross-section thin-wall part. The self-adaptive clamp comprises a clamp body for installing a driving assembly, a self-adaptive positioning assembly and a clamping assembly. A third round sleeve is arranged at the right end of the clamp body; a plurality of mounting holes penetrate through the outer circumference and the inner circumference of the clamp body; an arc-shaped block of the self-adaptive positioning assembly is arranged in the mounting hole; the driving assembly comprises a center shaft, a conical protruding block is arranged at the position, corresponding to the inner supporting sliding block, of the center shaft, and when the center shaft moves leftwards, circumferential supporting positioning is provided for a workpiece to be machined. The clamping assembly comprises a first round sleeve rotationally installed at the near end of the clamp body and a second round sleeve slidably arranged at the other end of the clamp body, and the second round sleeve is located on the inner side of a third round sleeve and adjustably connected to the third round sleeve through a lead screw and a spring. And the second round sleeve applies axial clamping force to a to-be-machined workpiece clamped between the first round sleeve and the second round sleeve through the elastic force of the spring.

Description

Technical Field

[0001] This invention relates to the field of machining fixture technology, and specifically to an adaptive fixture for precision machining of the outer diameter of thin-walled parts with variable cross-section. Background Technology

[0002] Variable cross-section thin-walled components are widely used in high-end equipment fields such as aerospace, automobile manufacturing, and precision instruments due to their lightweight structure, high material utilization rate, and compliance with modern industrial demands for efficient and energy-saving parts. The core characteristics of these parts are thin wall thickness, continuous variation of cross-sectional profile along the axial direction, and extremely high requirements for dimensional accuracy and surface quality during the finishing of the outer circle.

[0003] However, the structural characteristics of variable cross-section thin-walled parts make them prone to clamping deformation and cutting vibration during machining. On the one hand, traditional fixtures (such as three-jaw chucks and elastic sleeves) mostly use rigid clamping methods, resulting in uneven clamping force distribution. This can easily lead to local elastic deformation or even irreversible plastic deformation of thin-walled parts. After machining, stress release can cause the parts to spring back, making it impossible to guarantee dimensional accuracy. In severe cases, elliptical or tapered deviations may occur. On the other hand, due to the continuous change of the inner diameter of the parts, traditional fixtures are difficult to achieve a complete fit with the inner hole of the parts, resulting in poor clamping stability. During the cutting process, they are easily affected by centrifugal force and intermittent cutting impact, which can cause chatter. This not only causes defects such as chatter marks and roughening on the surface, affecting surface quality, but may also lead to accelerated tool wear, chipping, or even resonance of the parts, resulting in scrap.

[0004] In existing technologies, clamping solutions for thin-walled parts are mostly concentrated on parts with uniform inner diameters, such as multi-jaw linkage clamps or flexible pad clamps. These solutions reduce damage by evenly distributing clamping force or adding buffers. However, such clamps have poor structural rigidity and limited adjustment capabilities. They cannot adjust the clamping angle and contact position in real time according to the curvature changes of the inner hole of parts with variable cross-sections. For thin-walled parts with complex contours or irregular cross-sections, it is still difficult to achieve uniform clamping around the entire circumference. The clamping stability is insufficient, and micro-displacement or low-frequency vibration is prone to occur during finishing. The clamping fit is low and the self-adaptive ability is poor. Summary of the Invention

[0005] This invention proposes an adaptive fixture for the finishing of the outer diameter of thin-walled parts with variable cross-section. It can adaptively adjust the clamping state according to the inner hole contour of the thin-walled parts with variable cross-section, achieve uniform distribution of clamping force, effectively suppress clamping deformation and cutting vibration, and realize high-precision outer diameter machining.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: An adaptive fixture for finishing the outer diameter of a thin-walled part with variable cross-section includes: The clamping body assembly includes at least a clamping body with a hollow cylindrical structure for mounting the drive assembly, the adaptive positioning assembly, and the clamping assembly; a third circular sleeve is provided at the right end of the clamping body. Several sets of mounting slots are spaced apart along the length of the clamp body; each set of mounting slots includes several mounting holes arranged along the periphery of the clamp body to penetrate the outer and inner periphery of the clamp body. An adaptive positioning component is fitted into a mounting slot and moves closer to or further away from the central axis of the clamping body when the drive component moves; it includes an inner support slider, an arc-shaped block fixed on the inner support slider, and a flexible wear-resistant layer fixed on the arc-shaped block; The drive assembly includes at least a rotatable central shaft located at the center of the clamping body. The central shaft has a conical protrusion at a position corresponding to the inner support slider. When the central shaft moves to the left, the conical protrusion on the central shaft acts on the inner support slider, so that the inner support slider, the arc block and the flexible wear-resistant layer provide circumferential support and positioning to the workpiece to be processed. The clamping assembly includes at least a first circular sleeve mounted on the left end of the clamping body and a second circular sleeve slidably disposed on the right end of the clamping body. The left side of the first circular sleeve contacts the end face of the three-jaw chuck. The second circular sleeve is located inside the third circular sleeve and is adjustablely connected to the third circular sleeve by a screw and a spring. The second circular sleeve applies an axial clamping force to the workpiece to be processed, which is clamped between the first circular sleeve and the second circular sleeve, by the elastic force of the spring. The left end face of the workpiece to be processed contacts the right end face of the first circular sleeve, and the right end face contacts the left end face of the second circular sleeve.

[0007] As an improvement to the above technical solution, the left end of the fixture body is provided with a connecting end so that the fixture body is clamped and connected to the three-jaw chuck of the lathe through the connecting end. The connecting end and the third circular sleeve are respectively threaded to the left and right ends of the fixture body. The third circular sleeve is provided with an internal thread so that the central shaft can be placed on the third circular sleeve.

[0008] As an improvement to the above technical solution, the mounting slots are in three groups, each group of mounting slots is provided with three mounting holes, and the three mounting holes in one group are evenly spaced along the periphery of the clamp body; the corresponding adaptive clamping components are in nine groups, which are respectively installed in the nine mounting holes.

[0009] As an improvement to the above technical solution, a keyway is provided at one end of the inner support slider and the arc block so that the inner support slider and the arc block are connected by a keyway with interference fit. A flexible wear-resistant layer is provided on the outer periphery of the arc block so that the arc block contacts the inner periphery of the workpiece to be processed through the flexible wear-resistant layer.

[0010] As an improvement to the above technical solution, threaded holes are machined in the arc-shaped block and the flexible wear-resistant layer, so that the arc-shaped block and the flexible wear-resistant layer are fixed by screws.

[0011] As an improvement to the above technical solution, the flexible wear-resistant layer is made of polyurethane material with a thickness of 2-5mm, and the surface of the flexible wear-resistant layer is provided with anti-slip texture.

[0012] As an improvement to the above technical solution, there are three screws, which are fixedly connected to the second circular sleeve respectively. The third circular sleeve is provided with a through hole so that the screw can be adjusted and connected to the third circular sleeve through the through hole. The screw is connected to the third circular sleeve with double nuts. A spring is sleeved on the outer circumference of the screw so that one end of the spring abuts against the second circular sleeve and the other end abuts against the third circular sleeve.

[0013] As an improvement to the above technical solution, the inner support slider is provided with a spring mounting groove, and a spring is provided between the inner support slider and the arc block to ensure that the inner support slider, the arc block and the central axis always maintain close contact when the central axis moves to the left or right.

[0014] As an improvement to the above technical solution, the adaptive fixture includes a displacement measuring component, which includes a display and a capacitive grid connected to the display. A slot is provided at the right end of the central shaft so that the capacitive grid can be installed therein. The display is magnetically mounted on the outside of the third circular sleeve.

[0015] As an improvement to the above technical solution, a boss is machined on the upper end of the inner support slider to facilitate the setting of the zero point for displacement measurement.

[0016] Compared with the prior art, the advantages and positive effects of this invention are: The adaptive fixture of the present invention for finishing the outer diameter of thin-walled parts with variable cross-section can adaptively adjust the clamping state according to the inner hole contour of the thin-walled parts with variable cross-section, so as to achieve uniform distribution of clamping force, effectively suppress clamping deformation and cutting vibration, and thus achieve high-precision finishing of the outer diameter. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a cross-sectional view of the overall structure of an embodiment of the present invention; Figure 2 This is a cross-sectional view of the adaptive clamping component structure according to an embodiment of the present invention; Figure 3 This is a cross-sectional view of the overall structure of an embodiment of the present invention.

[0019] Reference numerals: 1. Connecting end; 2. First circular sleeve; 3. Fixture body; 4. Flexible wear-resistant layer; 5. Arc-shaped steel plate; 6. First spring; 7. First set of inner support sliders; 8. Second spring; 9. Second set of inner support sliders; 10. Third spring; 11. Third set of inner support sliders; 12. Key; 13. Second circular sleeve; 14. Fourth spring; 15. Third circular sleeve; 16. Display; 17. Capacitor grid; 18. Central shaft; 19. Screw; 20. Locking nut; 21. Fastening nut; 22. Workpiece; 23. Third set of mounting slots; 24. Second set of mounting slots; 25. First set of mounting slots; 26. Three-jaw chuck; 27. Set screw. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art to all other embodiments obtained without creative effort should be included within the protection scope of the present invention.

[0021] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments disclosed in this invention without creative effort are within the scope of protection of this invention.

[0022] In the description of this invention, it should be noted that the orientations or positional relationships indicated by terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" are all based on the orientations or positional relationships shown in the accompanying drawings. These descriptions are for the purpose of facilitating the explanation of the invention and simplifying the description, and do not imply or require that the referred device or element must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention. Furthermore, the terms "first," "second," and "third," etc., are used only for distinguishing purposes in the description and should not be interpreted as indicating or implying relative importance.

[0023] In the description of this invention, it should be further noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they may refer to a fixed connection, a detachable connection, or an integrally formed connection; they may be a mechanical connection or an electrical connection; they may be a direct connection or an indirect connection via an intermediate medium; they may also refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0024] Unless the context clearly indicates otherwise, the singular form is intended to include the plural form. The terms “comprising,” “including,” and “having” are used to enumerate the presence of the stated features, quantities, operations, components, elements, and / or combinations thereof, but do not preclude the presence or addition of one or more other features, quantities, operations, components, elements, and / or combinations thereof.

[0025] Due to manufacturing techniques and / or tolerances, the shapes shown in the figures may vary. Therefore, the examples described herein are not limited to the specific shapes shown in the figures, but should cover shape variations that may occur during the manufacturing process.

[0026] The exemplary embodiments will now be described in more detail with reference to the accompanying drawings.

[0027] Reference Figure 1 and Figure 3 The present invention provides an adaptive fixture for finishing the outer circle of a thin-walled part with variable cross-section, which mainly includes five parts: a fixture body assembly, a drive assembly, an adaptive positioning assembly, a clamping assembly, and a displacement measurement system.

[0028] Reference Figure 1 and Figure 3 The fixture assembly consists of a connecting end 1, a third circular sleeve 15, and a fixture body 3. The fixture body 3 is a hollow cylindrical structure with a threaded end on its left side. The outer circle of the left end of the connecting end 1 is fixed to the lathe by a three-jaw chuck 26. The left end of the fixture body 3 is threadedly connected to the right end of the connecting end 1, thus fixing the fixture body 3. The right end of the fixture body 3 is threadedly connected to the left end of the third circular sleeve 15, thus fixing the fixture body 3. The fixture body is a hollow cylindrical structure with three sets of mounting slots: the first set of mounting slots 25, the second set of mounting slots 24, and the third set of mounting slots 23. The mounting slots extend along the axial direction of the fixture body and are located at the midpoint of the different inner diameter axial dimensions of the workpiece to be processed. Each set of mounting slots has three mounting holes, which are evenly distributed on the same circumference of the fixture body 3, i.e., the mounting holes on the same set of mounting slots are spaced 120° apart. The third circular sleeve 15 has a central hole and through holes on its edge to facilitate the passage of the lead screw.

[0029] Reference Figure 1 and Figure 3 The drive assembly includes a drive component and a central shaft 18. The right end of the drive component is fixed to the tailstock tip of the lathe, and the left end of the drive component is fixedly connected to the right end of the central shaft 18. When the tailstock moves to the left, the drive component can drive the central shaft 18 to move to the left along the axial direction at the same time. Three conical bosses are machined on the central shaft 18. The spacing between the bosses is the same as the spacing between each set of mounting slots. A slot is machined on the rightmost shaft section to facilitate the installation of the retaining grid 17.

[0030] Reference Figure 1 , Figure 2 and Figure 3 The adaptive positioning component mainly consists of a first set of inner support sliders 7, a second set of inner support sliders 9, a third set of inner support sliders 11, a first spring 6, a second spring 8, a third spring 10, a flexible wear-resistant layer 4, an arc-shaped steel plate 5, a key 12, and a set screw 27. First, the central axis is moved to the left until the position of the truncated cone corresponds to the position of the mounting hole. The first set of inner support sliders 7 is then installed into the mounting hole of the first set of mounting slots 25. The first set of inner support sliders 7 is fixed on the same circumference by the first spring 6. For ease of installation, a double-hook spring is selected for the first spring 6. The arc-shaped steel plate 5 and the flexible wear-resistant layer 4 are similar in size, and through holes are machined at corresponding positions on both. They are connected as one unit by the set screw 27. Keyways are machined on the upper right side of the first set of inner support sliders 7 and the right side of the arc-shaped steel plate 5. The two are connected as one unit by a key, which is a small interference fit. The second set of inner support sliders 9 and the third set of inner support sliders 11 use the same installation method. After the adaptive positioning assembly is installed, the three sets of inner support sliders retract towards the central axis 18 due to the elastic force of the three springs. Retraction stops when the upper boss of the inner support slider is in close contact with the outer surface of the fixture body, at which point the workpiece is installed. The upper surface of the inner support slider is configured as an arc-shaped contact surface adapted to the inner bore contour of the variable cross-section thin-walled part. The lower surface of the inner support slider near the central axis is configured as an inclined surface, and the central axis is in contact with its inclined surface. When the central axis moves to the left, the inclined surface can push the inner support slider to move radially outward to position and support the workpiece.

[0031] Reference Figure 1 and Figure 3 The clamping assembly includes a first circular sleeve 2, a second circular sleeve 13, a third circular sleeve 15, a screw 19, a fourth spring 14, a fastening nut 20, and a locking nut 21. The left end face of the first circular sleeve 2 is pressed against the three-jaw chuck 26, and the right end face of the first circular sleeve 2 is pressed against the left end face of the workpiece 22. The right end face of the workpiece 22 is pressed against the left end face of the second circular sleeve 13. The second circular sleeve 13 can slide on the clamping body 3. The third sleeve 15 is threadedly connected to the clamping body 3 and remains fixed. The fourth spring 14 is placed between the second circular sleeve 13 and the third circular sleeve 15, and the fourth spring 14 is kept in a compressed state, applying pressure to the left to press the workpiece 22 to the left. After the workpiece 22 is pressed, the screw 19 passes through the fourth spring 14 and the third circular sleeve 15, and is threadedly connected to the right end face of the second circular sleeve 13. Starting from the right end of screw 19, tighten the fastening nut 20, controlling the fourth spring 14 to apply the same axial clamping force to the workpiece. After the fastening nut 20 is tightened to the correct position, add the locking nut 21. This double-nut anti-loosening structure ensures the workpiece is always clamped and subjected to uniform axial force. To ensure more uniform force distribution during the tightening process to the left, the screw is configured with three sets.

[0032] Reference Figure 1 and Figure 3 The displacement measurement component mainly consists of a display 16 and a capacitive grid 17. The capacitive grid 17 is installed in a groove machined in the rightmost section of the central shaft 18. The display 16 has a built-in magnetic attraction device and a fixed grid sensor. The display 16 is attached to the right end face of the third circular sleeve 15 by the built-in magnetic attraction device. When the bosses on the upper ends of the inner support sliders 7, 9, and 11 are close to the outer circular surface of the clamping body under the clamping force of the springs 6, 8, and 10, the lower arc surface of the inner support sliders 7, 9, and 11 is in contact with the inclined surface of the conical boss on the central shaft 18. This is the zero point measured by the display. When the central shaft 18 moves to the left under the action of the driving component, it drives the capacitive grid 17 to move to the left, while the display remains stationary. The built-in fixed grid sensor converts the displacement generated by the two into an electrical signal, causing a change in the display. The radial displacement of the inner support sliders 7, 9, and 11 can be determined by the digital measurement of the display, thereby controlling the displacement of the flexible wear-resistant layer 4. Considering the influence of the error in the inner diameter of each component of the fixture and the workpiece to be processed, after the flexible wear-resistant layer 4 comes into contact with the inner circumference of the workpiece to be processed, the central axis continues to move to the left. According to the actual processing situation, the flexible wear-resistant layer 4 moves radially by several micrometers to achieve complete positioning support of the inner circumference of the workpiece to be processed.

[0033] Of course, to accommodate the diameter changes at different axial positions of the inner hole of the variable cross-section thin-walled component, the inner support sliders at different axial positions are set to different heights to adapt to the variable cross-section thin-walled component. Simultaneously, for ease of installation, the first spring 6, the second spring 8, and the third spring 10 are double-hook springs. In this invention, the flexible wear-resistant layer 4 and the fourth spring 14 also serve to absorb energy and reduce vibration.

[0034] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A self-adapting fixture for external cylindrical finishing of a variable cross-section thin-walled part, characterized in that: The utility model relates to a chuck body and a chuck body assembly, and belongs to the field of machine tool. The chuck body comprises a hollow cylindrical structure, and is provided with a third cylindrical sleeve at the right end of the chuck body. A plurality of groups of mounting grooves are arranged at intervals along the length direction of the chuck body. The adaptive positioning assembly is clamped in the mounting groove and moves closer to or further away from the central axis of the chuck body when the driving assembly is in operation. The driving assembly comprises a central shaft arranged at the center of the chuck body and rotatable. The central shaft is provided with a conical protrusion at the corresponding position of the inner support slider.

2. The self-adapting fixture for finish machining of the external circle of the thin-walled part with variable cross-section according to claim 1, characterized in that: When the central shaft moves to the left, the conical protrusion on the central shaft acts on the inner support slider, so that the inner support slider, the arc-shaped block and the flexible wear-resistant layer provide circumferential support positioning for the workpiece to be machined.

3. The self-adapting fixture for finish machining of the external circle of the thin-walled part with variable cross-section according to claim 1, characterized in that: The chucking assembly comprises a first cylindrical sleeve arranged at the left end of the chuck body and a second cylindrical sleeve arranged at the right end of the chuck body and slidable.

4. The self-adapting fixture for finish machining of the external circle of the thin-walled part with variable cross-section according to claim 1, characterized in that: The first cylindrical sleeve is in contact with the end face of the three-jaw chuck.

5. The self-adapting fixture for finish machining of the external circle of the thin-walled part with variable cross-section according to claim 1, characterized in that: The second cylindrical sleeve is located inside the third cylindrical sleeve and is adjustably connected to the third cylindrical sleeve through a screw and a spring.

6. The self adaptive fixture for finish machining of the external cylindrical surface of the thin-walled workpiece with variable cross-section as claimed in claim 1 wherein: The second cylindrical sleeve exerts axial clamping force on the workpiece to be machined clamped between the first cylindrical sleeve and the second cylindrical sleeve by the elastic force of the spring.

7. The self adaptive fixture for finish machining of the external cylindrical surface of the thin-walled workpiece with variable cross-section as claimed in claim 4 wherein: The left end of the chuck body is provided with a connecting end to enable the chuck body to be clamped and connected to the three-jaw chuck of the lathe through the connecting end.

8. The self adaptive fixture for finish machining of the external cylindrical surface of the thin-walled workpiece with variable cross-section as claimed in claim 4 wherein: The connecting end and the third cylindrical sleeve are respectively threadedly connected to the left end and the right end of the chuck body. The third cylindrical sleeve is provided with internal threads to enable the central shaft to be placed through the third cylindrical sleeve. The mounting grooves are arranged in three groups, and each group of mounting grooves is provided with three mounting holes arranged at intervals along the periphery of the chuck body. The adaptive clamping assembly is correspondingly arranged in nine groups and is respectively arranged in the nine mounting holes. One end of the inner support slider and the arc-shaped block is provided with a key groove to enable the inner support slider and the arc-shaped block to be connected through the key. The arc-shaped block is an arc-shaped steel plate, and the arc-shaped steel plate is provided with a threaded hole to enable the arc-shaped steel plate to be fixed to the flexible wear-resistant layer through a screw. The flexible wear-resistant layer is made of polyurethane material and has a thickness of 2-5 mm. The surface of the flexible wear-resistant layer is provided with anti-skid lines. The third cylindrical sleeve is provided with a through hole corresponding to the screw to enable the screw to be adjustably connected to the third cylindrical sleeve through the through hole. The inner support slider is provided with a spring mounting groove, and a spring is arranged between the inner support slider and the arc-shaped block to ensure that the inner support slider, the arc-shaped block and the central shaft are in close contact when the central shaft moves to the left or to the right.

9. The self adaptive fixture for finish machining of the external cylindrical surface of the thin-walled workpiece with variable cross-section as claimed in claim 4 wherein: The self-adapting clamp comprises a displacement measuring assembly, which comprises a display and a capacitive gate connected with the display, and a groove is arranged at the right end of the central shaft so that the capacitive gate is installed in the groove, and the display is installed outside the third circular sleeve through magnetic attraction.

10. The self-adapting fixture for finish machining of the external circle of the thin-walled part with variable cross-section according to claim 9, characterized in that: The upper end of the inner support sliding block is processed as a boss to facilitate setting of a displacement measuring zero point.

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