A clamping tool for machining a thin-walled cylinder and a machining process

Abstract

This invention discloses a clamping fixture and processing technology for machining thin-walled cylindrical parts, relating to the field of aerospace component manufacturing. The invention includes a clamping assembly that holds one end of the thin-walled cylindrical part to be machined and a hydraulic center frame at the other end. The clamping assembly includes a chuck, a clamping cylinder, and a locking ring. The clamping cylinder and locking ring are both sleeved on the outer wall of the thin-walled cylindrical part and are located on both sides of an axial positioning protrusion ring. The side of the clamping cylinder facing the axial positioning protrusion ring has a first inner oblique cone surface adapted to and pressed against a first outer oblique cone surface. The side of the locking ring facing the axial positioning protrusion ring has a second inner oblique cone surface adapted to and pressed against a second outer oblique cone surface. The cooperation of the two sets of oblique cone surfaces allows the clamping cylinder and locking ring to be axially pressed against the outer wall of the thin-walled cylindrical part from both sides, and the connection and locking are achieved through a first and second joint structure. This avoids the deformation of the cylindrical part caused by the difficulty in controlling the clamping force when the chuck directly clamps radially against the outer wall of the thin-walled cylindrical part.

Description

Technical Field

[0001] This invention relates to the field of aerospace component manufacturing, specifically to the processing technology of aluminum alloy thin-walled outer cylinders in flight control systems, and more specifically to a clamping fixture and processing technology for processing thin-walled cylinders. Background Technology

[0002] In flight control systems, actuators are the core actuators that enable precise control surface maneuvering, often referred to as the "muscles" of the flight control system. Their outer cylinders, as typical thin-walled long cylindrical key components, not only bear the core functions of structural load-bearing and transmitting hydraulic or pneumatic pressure, but also directly determine the actuation accuracy and overall system reliability.

[0003] To achieve lightweight design, the outer cylinder is generally made of high-strength aluminum alloys (such as heat-treatable Al-Cu and Al-Zn alloys). Although these materials possess excellent specific strength, their thin-walled components are highly susceptible to deformation during machining, making morphological and dimensional accuracy control the primary challenge in the manufacturing process. Machining deformation is mainly affected by two major factors: internal and external.

[0004] External deformation mainly refers to the deformation of thin-walled cylindrical parts during machining, where improper clamping force can directly lead to deformation of the outer cylinder. Some solutions use floating three-jaw chucks to clamp the workpiece, adding a floating mechanism, such as a spring, to allow the jaws a certain amount of floating allowance in the radial direction, thus adjusting their clamping force automatically. However, this type of floating chuck, affected by the floating mechanism, has insufficient rigidity and may still vibrate during machining, affecting machining accuracy. Furthermore, it is costly, complex in design and manufacturing, and requires a long clamping preparation time; adjustment and alignment are more time-consuming than with ordinary rigid chucks.

[0005] Intrinsic deformation mainly refers to deformation caused by a significant increase in internal stress during processing due to the removal of large amounts of material, as well as deformation caused by residual stress or instability in the material's microstructure after processing, leading to changes in the outer cylinder's dimensions and deformation in the later stages of processing or after a period of time. Current processes often utilize stress-relieving heat treatment and multiple precision machining corrections to improve material stability and reduce the possibility of later deformation; however, these methods have long processing cycles, are time-consuming and costly, and result in inconsistent product quality.

[0006] Therefore, how to improve the above-mentioned clamping deformation and the workpiece deformation caused by stress and material instability is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] In view of this, the present invention aims to provide a clamping fixture and processing technology for machining thin-walled cylindrical parts to at least partially solve the problems of workpiece deformation caused by improper clamping force and workpiece deformation caused by stress and material instability during the machining process in the prior art.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A clamping fixture for machining thin-walled cylindrical parts includes an axial positioning protrusion formed on the outer wall surface of the thin-walled cylindrical part to be machined. The two ends of the axial positioning protrusion are arranged along the axial direction of the thin-walled cylindrical part and are connected to the outer wall surface by a first external oblique cone surface and a second external oblique cone surface, respectively. The fixture includes a clamping assembly that clamps one end of the thin-walled cylindrical part to be machined and a hydraulic center frame at the other end. The clamping assembly includes a chuck, a clamping cylinder, and a locking ring. The clamping cylinder and the locking ring are both sleeved on the outer wall of the thin-walled cylinder and are respectively located on both sides of the axial positioning protrusion. The side of the clamping cylinder facing the axial positioning protrusion is provided with a first inner oblique cone surface that is adapted to and pressed against the first outer oblique cone surface. The side of the locking ring facing the axial positioning protrusion is provided with a second inner oblique cone surface that is adapted to and pressed against the second outer oblique cone surface. The opposite sides of the clamping cylinder and the locking ring are respectively provided with a first engagement structure and a second engagement structure that can be adapted to engage and lock the two. The clamping cylinder can be clamped at the clamping end of the chuck.

[0010] The beneficial effects achievable by this invention are as follows: By utilizing the cooperation of two sets of inclined conical surfaces, the clamping cylinder and the locking ring are axially pressed against the outer wall surface of the axial positioning convex ring from both sides of the thin-walled cylinder, and are connected and locked through the first and second joint structures. This avoids the cylinder deformation caused by the difficulty in controlling the clamping force when the chuck is directly radially clamped on the outer wall of the thin-walled cylinder. Furthermore, the clamping cylinder and the locking ring are arranged coaxially with the cylinder, making it easy to center and ensuring the machining accuracy of the cylinder.

[0011] Preferably, the locking ring comprises: An adjusting washer is coaxially and slidably sleeved on the outer wall of the thin-walled cylindrical component, and a second inner inclined cone surface is provided on its inner side wall; A locking collar, comprising a coupling sleeve and a washer pressure ring, wherein the coupling sleeve is coaxially slidably sleeved on the outer periphery of the adjusting washer, and the second coupling structure is disposed on the side of the coupling sleeve near the clamping cylinder; the washer pressure ring is fixed to the inner wall surface of the coupling sleeve away from the clamping cylinder, and can press the adjusting washer onto the second outer inclined cone surface.

[0012] Preferably, a guide cylinder is coaxially fixed at the end of the clamping cylinder near the connecting sleeve; a positioning cylinder is coaxially fixed at the end of the adjusting washer near the clamping cylinder; the positioning cylinder is placed in the inner cavity of the connecting sleeve and can be axially slidably sleeved on the outer wall of the guide cylinder.

[0013] Preferably, the adjusting washer is formed by circumferentially splicing multiple arc-shaped parts.

[0014] Preferably, the first engagement structure is an external thread, and the second engagement structure is an internal thread that is threadedly connected to the external thread.

[0015] A thin-walled cylindrical component processing technology includes the following steps: S10. Rough turning of inner and outer cavities: The blank is clamped with a general-purpose chuck, and the inner and outer cavities are turned to remove the blank allowance. S11. Stabilization heat treatment: Using an air furnace, the temperature is heated to 90℃~120℃, held for 12h~14h, and then air-cooled with the furnace to achieve dimensional stabilization treatment, reducing workpiece deformation and stress corrosion tendency. S12. Semi-finish turning of inner and outer cavities: When machining the outer cavity, use a two-center clamping fixture to clamp the workpiece, and leave a finishing allowance of 0.1 mm to 0.15 mm on the surface and the outer diameter of the thread during machining; when machining the inner cavity, use the aforementioned clamping fixture for machining thin-walled cylindrical parts to clamp the workpiece, and leave a finishing allowance of 0.15 mm to 0.2 mm during machining. S13. Cyclic stabilization treatment: The workpiece is subjected to cyclic cold and heat treatment to stabilize gradient and stress changes, accelerate the metal recovery process, and form a more stable dislocation structure, thereby achieving long-term stability of part dimensions. S14. Precision machining of inner and outer cavities: The workpiece is clamped using the clamping method in S12, and both the inner and outer cavities of the workpiece are machined to the dimensions shown in the drawing.

[0016] The beneficial effects achievable by this invention are as follows: After rough turning, stress is relieved by stabilizing heat treatment to achieve initial dimensional stabilization of the workpiece. Subsequently, after semi-finish turning, cyclic cold and heat treatment is used to further stabilize the gradient and stress changes within the material, accelerate the material recovery process, and form a relatively stable dislocation structure. This achieves long-term dimensional stability of the part and avoids deformation of the workpiece caused by changes in the internal components of the material over time during subsequent processing or after the workpiece is formed, which would affect the assembly accuracy and sealing performance of other parts.

[0017] Preferably, in S12, the step of clamping the workpiece using a clamping fixture for thin-walled cylindrical parts as described above includes the following steps: S121. Install the clamping cylinder: Clamp the clamping cylinder onto the chuck and align the axis runout; S122. Install the workpiece: Place the thin-walled cylindrical part to be processed on one side corresponding to its first end into the inner cavity of the clamping cylinder, ensuring that the first outer oblique cone surface on the thin-walled cylindrical part fits against the first inner oblique cone surface on the clamping cylinder. S123. Install the locking ring: Install the locking ring on the thin-walled cylindrical part so that its second inner oblique cone surface fits against the second outer oblique cone surface of the thin-walled cylindrical part to be processed; S124. Locking ring locking: A hydraulic center frame is set at the second end of the thin-walled cylinder and clamped on the outer wall surface of the thin-walled cylinder corresponding to its second end. After aligning the axis, the second engagement structure of the locking ring engages and locks with the first engagement structure on the clamping cylinder to complete the clamping work.

[0018] Preferably, in S13, the cyclic cold and heat treatment of the workpiece specifically includes: S131. Clean the dirt, residual metal shavings and oil stains on the surface of the parts with a cleaning agent and let them air dry. S132. Reduce the workpiece temperature to -170℃~-195℃, hold for 1 hour, and then air cool with the furnace. S133. After the frost on the surface of the parts melts, heat it to 90℃~120℃ and hold it for 1h~2h, then air cool it with the furnace. S134. Repeat steps S132-S133 to perform multiple cold and hot cycle treatments.

[0019] Preferably, it also includes S15, surface treatment: oxidizing the surface of the finished workpiece.

[0020] Preferably, it also includes S16, grinding the inner cavity: manually grinding the inner cavity of the workpiece to improve the morphological quality of the inner cavity, thereby further improving its wear resistance and sealing performance.

[0021] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a clamping fixture and processing technology for processing thin-walled cylindrical parts. The clamping fixture can be used in conjunction with existing chucks, improving the flexibility of use; the clamping fixture achieves axial clamping by engaging the corresponding conical surfaces of the clamping cylinder, locking ring, and axial limiting structure on the outer wall of the cylindrical part, avoiding deformation caused by radial clamping of the workpiece; the adjusting washer is formed by circumferentially splicing multiple arc-shaped parts, which is convenient for installation and avoids the influence of other structures on the outer surface of the workpiece; the pressing mating surface is a conical surface, which, combined with the threaded locking between the clamping cylinder and the locking ring, can... The invention achieves stepless adjustment, enhancing the clamping force between each component and the thin-walled cylindrical part. The machining process involves stress relief through preliminary heat treatment after rough turning, followed by stabilization through cyclic cold and hot cycles after semi-finish turning, enhancing material stability and preventing deformation caused by residual stress or changes in the microstructure within the cylindrical part material. During machining, the workpiece is clamped using the clamping fixture of this invention, employing multi-stage progressive centering to ensure the installation accuracy of each structure, laying the foundation for improving the machining accuracy of the thin-walled cylindrical part. Furthermore, the workpiece is held at one end by a clamping device and supported at the other end by a hydraulic center frame, ensuring stability during machining. Attached Figure Description

[0022] 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 embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the structure of a clamping fixture for processing thin-walled cylindrical parts provided by the present invention, used to clamp the thin-walled cylindrical parts to be processed.

[0024] Figure 2 This is a cross-sectional structural diagram of a clamping fixture for machining thin-walled cylindrical parts provided by the present invention, used to clamp the thin-walled cylindrical parts to be machined.

[0025] Figure 3 for Figure 2 A magnified structural diagram of part A in the diagram.

[0026] Figure 4 This is a schematic diagram of a half-section of the clamping cylinder provided by the present invention.

[0027] Figure 5 This is a schematic diagram of the adjusting washer structure provided by the present invention.

[0028] Figure 6 This is a schematic diagram of the cross-sectional structure of the adjusting washer provided by the present invention.

[0029] Figure 7This is a schematic diagram of the cross-sectional structure of the locking collar provided by the present invention.

[0030] Figure 8 A process flow diagram for processing thin-walled cylindrical parts provided by the present invention.

[0031] In the picture: 1. Clamping assembly; 11. Clamping cylinder; 111. First inner oblique conical surface; 112. First engagement structure; 113. Large diameter section; 114. Small diameter section; 113. Limiting ring; 12. Locking ring; 121. Adjusting washer; 1211. Second inner oblique conical surface; 122. Locking collar; 1221. Engaging sleeve; 12211. Second engagement structure; 1222. Washer pressure ring; 13. Guide cylinder; 14. Positioning cylinder; 2. Hydraulic center frame; 3. Thin-walled cylinder; 31. First outer oblique conical surface; 32. Second outer oblique conical surface; 33. First end; 34. Second end. Detailed Implementation

[0032] 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, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention 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. Therefore, they should not be construed as limitations on this invention.

[0034] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction 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.

[0035] Example 1: Please see Figures 1-7In order to improve the clamping deformation of the thin-walled cylindrical part 3, this embodiment discloses a clamping fixture for processing thin-walled cylindrical parts. An axial positioning protrusion ring is provided on the outer wall surface of the thin-walled cylindrical part 3 to be processed. The two ends of the axial positioning protrusion ring arranged along the axial direction of the thin-walled cylindrical part 3 are connected to its outer wall surface through a first outer oblique cone surface 31 and a second outer oblique cone surface 32, respectively. The clamping fixture includes a clamping assembly 1 clamping the thin-walled cylindrical part 3 at the first end 33 to be processed and a hydraulic center frame 2 arranged opposite to the second end 34. The clamping assembly 1 includes a chuck, a clamping cylinder 11 and a locking ring 12. The chuck is a general chuck in the prior art, usually a multi-jaw chuck.

[0036] The clamping cylinder 11 and the locking ring 12 are both sleeved on the outer wall of the thin-walled cylinder 3 and are located on both sides of the axial positioning protrusion ring respectively; the clamping cylinder 11 is provided with a first inner oblique cone surface 111 that is adapted to and pressed against the first outer oblique cone surface 31 on the side facing the axial positioning protrusion ring; the locking ring 12 is provided with a second inner oblique cone surface 1211 that is adapted to and pressed against the second outer oblique cone surface 32 on the side facing the axial positioning protrusion ring; the clamping cylinder 11 and the locking ring 12 are respectively provided with a first engagement structure 112 and a second engagement structure 12211 that can be adapted to engage and lock the two; the clamping cylinder 11 can be clamped at the clamping end of the chuck. Therefore, by utilizing the cooperation between the first inner oblique cone surface 111 on the clamping cylinder 11 and the first outer oblique cone surface 31 on the thin-walled cylinder 3, and the second inner oblique cone surface 1211 on the locking ring 12 and the second outer oblique cone surface 32 on the thin-walled cylinder 3, the clamping cylinder 11 and the locking ring 12 are axially pressed from both sides of the thin-walled cylinder 3 and locked through the first joint structure 112 and the second joint structure 12211, thereby avoiding the deformation caused by the chuck's claws directly and radially clamping the outer wall of the cylinder.

[0037] In one specific implementation, the axial positioning protrusion is a protrusion integrally formed on the outer wall of the thin-walled cylinder 3. In some other implementations, the axial positioning protrusion can be a positioning protrusion attached to the outer wall of the thin-walled cylinder 3 by means of mechanical connection.

[0038] In one specific implementation, there is a 0.1 mm gap between the inner cylindrical surface of the clamping cylinder 11 and the outer wall surface of the thin-walled cylinder 3, so as to ensure that the clamping cylinder 11 can be slidably sleeved on the outside of the thin-walled cylinder 3.

[0039] In one specific embodiment, the outer diameter of the clamping cylinder 11 decreases in a stepped manner from the direction away from the locking ring 12 to form a stepped cylindrical structure. Its large-diameter section 113 is clamped at the clamping end of the chuck, and a first engaging structure 112 is provided on the outer wall surface of the small-diameter section 114 to engage and lock with the locking ring 12. Thus, the portion of the clamping cylinder 11 clamped by the chuck claws has a thicker wall, improving its resistance to deformation and preventing deformation from being transmitted to the thin-walled cylindrical component 3. Furthermore, the clamping cylinder 11 can also be made of a hard, rigid material, such as stainless steel, to further enhance its resistance to deformation.

[0040] In one specific implementation, a limit ring 115 is provided on the outer wall surface of the large-diameter section 113 of the clamping cylinder 11, corresponding to the side near the locking ring 12, to limit the axial movement of the chuck and prevent the chuck from sliding to the small-diameter section 114 due to insecure clamping, or even damaging the thin-walled cylinder 3.

[0041] In one specific implementation, the locking ring 12 includes: Adjusting washer 121 is fitted onto the outer wall of thin-walled cylindrical part 3, and a second inner inclined cone surface 1211 is provided on its inner side wall; The locking collar 122 includes a connecting sleeve 1221 and a washer pressure ring 1222. The connecting sleeve 1221 is sleeved on the outer periphery of the adjusting washer 121. The second connecting structure 12211 is disposed on the side of the connecting sleeve 1221 near the clamping cylinder 11. The washer pressure ring 1222 is fixed to the inner wall surface of the connecting sleeve 1221 away from the clamping cylinder 11, and it can abut against the adjusting washer 121 to press it onto the second outer inclined cone surface 32.

[0042] In one specific embodiment, a guide cylinder 13 is coaxially fixed to the end of the clamping cylinder 11 near the engaging sleeve 1221; a positioning cylinder 14 is coaxially fixed to the end of the adjusting washer 121 near the clamping cylinder 11; the positioning cylinder 14 is placed in the inner cavity of the engaging sleeve 1221 and can be axially slidably sleeved on the outer wall of the guide cylinder 13. The sleeved connection between the guide cylinder 13 and the positioning cylinder 14 serves an orientation function, enhances the constraint force between the adjusting washer 121 and the clamping cylinder 11, and improves coaxiality.

[0043] In a specific implementation, such as Figure 5 As shown, the adjusting washer 121 is formed by circumferentially splicing multiple arc-shaped parts. This facilitates the fitting of the adjusting washer 121 onto the thin-walled cylindrical member 3, eliminating the need to insert it from the end of the longer thin-walled cylindrical member 3 and preventing obstruction from other structures on the outer wall of the thin-walled cylindrical member 3. Preferably, two arc-shaped parts are provided, each with a semi-circular structure. When interlocked, they form a complete circular adjusting washer 121, avoiding problems such as inconvenience in installation and impact on installation accuracy caused by an excessive number of arc-shaped parts.

[0044] In one specific implementation, the first engagement structure 112 is an external thread, and the second engagement structure 12211 is an internal thread that is threaded to the external thread. The locking collar 122 and the clamping cylinder 11 are connected by threads, which is convenient to process, has a reliable connection, and can realize stepless adjustment of the position of the locking collar 122, ensuring that the clamping cylinder 11 and the adjusting washer 121 are axially pressed against the corresponding inclined cone surface of the thin-walled cylinder 3.

[0045] Example 2: See Figure 8This embodiment provides a thin-walled cylindrical component processing technology to mitigate the impact of stress and material instability during the processing of the thin-walled cylindrical component 3, including the following steps: S10. Rough turning of inner and outer cavities: The blank is clamped with a universal chuck (i.e., the existing multi-jaw rigid chuck) and the inner and outer cavities are turned to remove the blank allowance, so that the material stress generated during the cutting process can be fully released.

[0046] S11. Stabilization heat treatment: After rough machining, the cylindrical part is placed in an air furnace and heated to 90℃~120℃. After holding at this temperature for 12h~14h, it is air cooled with the furnace to achieve dimensional stabilization treatment and reduce workpiece deformation and stress corrosion tendency. S12. Semi-finish turning of inner and outer cavities: This involves completing the allowance again to reduce deformation caused by cutting. Specifically, when machining the outer cavity, a two-center clamping fixture is used to axially clamp the workpiece from both ends, leaving a finishing allowance of 0.1 mm to 0.15 mm on the surface and thread outer diameter; when machining the inner cavity, a clamping fixture for thin-walled cylindrical parts as described in Example 1 is used to clamp the workpiece, leaving a finishing allowance of 0.15 mm to 0.2 mm. S13. Cyclic stabilization treatment: The workpiece is subjected to cyclic cold and heat treatment to stabilize gradient and stress changes, accelerate the metal recovery process, and form a more stable dislocation structure, thereby achieving long-term stability of part dimensions.

[0047] S14. Finish machining of inner and outer cavities: Clamp the workpiece again using the clamping method in S12, and machine both the inner and outer cavities of the workpiece to the dimensions shown in the drawing.

[0048] In S12, the two-center clamping fixture is existing technology and will not be described in detail here. However, using the clamping fixture for machining thin-walled cylindrical parts as described in Example 1 to clamp the workpiece includes the following steps: S121. Install the clamping cylinder 11: Clamp the clamping cylinder 11 onto the chuck and align the axis runout. The specific operation method for aligning the axis runout is existing technology and will not be described in detail here.

[0049] S122. Install the workpiece: Place the first end 33 of the thin-walled cylindrical part 3 to be processed into the inner cavity of the clamping cylinder 11, ensuring that the first outer oblique cone surface 31 on the thin-walled cylindrical part 3 fits against the first inner oblique cone surface 111 on the clamping cylinder 11.

[0050] S123. Install the locking ring 12: Install the locking ring 12 on the thin-walled cylindrical part 3, so that its second inner oblique cone surface 1211 fits against the second outer oblique cone surface 32 of the thin-walled cylindrical part 3 to be processed; during installation, first install the adjusting washer 121, so that the second inner oblique cone surface 1211 on the adjusting washer 121 fits against the second outer oblique cone surface 32 on the thin-walled cylindrical part 3, and the positioning cylinder 14 and guide cylinder 13 at the end of the adjusting washer 121 are sleeved together; then the locking sleeve 122 is sleeved on the outer periphery of the adjusting washer 121, so that the inner cylindrical surface of the engaging sleeve 1221 fits against the outer wall surface of the adjusting washer 121.

[0051] S124, Locking Ring 12 Locking: A hydraulic center frame 2 is set at the second end 34 of the thin-walled cylindrical part 3 and the hydraulic center frame 2 is clamped on the outer wall surface of the thin-walled cylindrical part 3 corresponding to its second end 34. The thin-walled cylindrical part 3 is rotated and the axial runout of the thin-walled cylindrical part 3 is adjusted to no more than 0.02 mm using a dial indicator. The locking ring 122 is screwed on to lock it with the clamping cylinder 11 thread, so as to press the adjusting washer 121 on the second outer inclined cone surface 32 and complete the clamping work.

[0052] In one specific implementation, S13 involves cyclically performing cold and heat treatments on the workpiece, specifically including: S131. Clean the dirt, residual metal shavings and oil stains on the surface of the cylinder with a cleaning agent and dry it. Compressed air can be used to blow it dry to improve the drying efficiency.

[0053] S132. First, perform cold treatment. Place the cylinder in a cryogenic chamber to lower the temperature to -170℃~-195℃ and keep it warm for 1 hour. Then, air cool it with the furnace.

[0054] S133. After the frost on the surface of the parts melts, place the parts stably in the heating furnace, and heat them to 90℃~120℃. Hold them at that temperature for 1h~2h, and then air cool them with the furnace. During this period, the interval between the end of the cold treatment and the start of the heat treatment shall not exceed 2h.

[0055] S134. Repeat steps S132-S133 to perform cold and hot cycle treatment. One cold treatment plus one hot treatment constitutes one cycle, and the number of cycles shall not be less than 2.

[0056] In a specific implementation, in S14, the finishing process parameters for the outer diameter are as follows: VCGX 11 03 02 FN-25P is used, with a layered feed method, feed rate f=0.04 mm / r, depth of cut ap=0.1 mm, spindle speed v=1000 r / min, and sufficient cooling.

[0057] Precision machining parameters for the inner cavity: VCGX 11 03 02 FN-25P spindle, layered feed method, feed rate f=0.03 mm / r, depth of cut ap=0.05 mm, spindle speed v=800 r / min, and inner cavity cooling.

[0058] In one specific implementation, it also includes S15, surface treatment: electrochemical oxidation treatment of the surface of the finished workpiece. Specifically, electrochemical oxidation treatment refers to hard anodizing the inner cavity of the workpiece to increase its surface hardness, corrosion resistance, and insulation, achieving the goal of "rigid outside and flexible inside" and improving the service life of the cylinder. Ordinary anodizing is simultaneously performed on the remaining surfaces to provide corrosion protection.

[0059] In one specific implementation, it also includes S16, grinding the inner cavity: manually grinding the inner cavity of the workpiece to improve the morphological quality of the inner cavity, thereby further improving its wear resistance and sealing performance.

[0060] The processing technology in this embodiment realizes the entire process of thin-walled cylindrical part 3 from raw bar stock to final product. Through technical solutions such as inter-process allowance control, process parameter optimization, deformation prevention control, and improved clamping methods, it effectively solves technical problems such as cutting deformation, clamping deformation, and unstable morphology quality caused by unstable morphology materials, thereby improving morphology quality and shortening the processing cycle. This invention is highly operable, has broad application prospects, and has significant economic and social value.

[0061] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0062] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A clamping fixture for machining thin-walled cylindrical parts, wherein an axial positioning protrusion is provided on the outer wall surface of the thin-walled cylindrical part (3) to be machined, and the two ends of the axial positioning protrusion arranged along the axial direction of the thin-walled cylindrical part (3) are respectively connected to its outer wall surface by a first external oblique cone surface (31) and a second external oblique cone surface (32); characterized in that, It includes a clamping assembly (1) clamping one end of the thin-walled cylindrical part (3) to be processed and a hydraulic center frame (2) at the other end. The clamping assembly (1) includes a chuck, a clamping cylinder (11) and a locking ring (12). The clamping cylinder (11) and the locking ring (12) are both sleeved on the outer wall of the thin-walled cylinder (3) and are respectively located on both sides of the axial positioning protrusion. The clamping cylinder (11) is provided with a first inner oblique cone (111) that is adapted to and pressed against the first outer oblique cone (31) on the side facing the axial positioning protrusion. The locking ring (12) is provided with a second inner oblique cone (1211) that is adapted to and pressed against the second outer oblique cone (32) on the side facing the axial positioning protrusion. The clamping cylinder (11) and the locking ring (12) are respectively provided with a first engagement structure (112) and a second engagement structure (12211) that can be adapted to engage and lock the two. The clamping cylinder (11) can be clamped at the clamping end of the chuck.

2. The clamping fixture for machining thin-walled cylindrical parts according to claim 1, characterized in that, The locking ring (12) includes: Adjusting washer (121), the adjusting washer (121) is coaxially slidably sleeved on the outer wall of the thin-walled cylindrical part (3), and the second inner inclined cone surface (1211) is provided on its inner side wall. The locking collar (122) includes a connecting sleeve (1221) and a washer pressure ring (1222). The connecting sleeve (1221) is coaxially slidably sleeved on the outer periphery of the adjusting washer (121). The second connecting structure (12211) is disposed on the side of the connecting sleeve (1221) close to the clamping cylinder (11). The washer pressure ring (1222) is fixed to the inner wall surface of the connecting sleeve (1221) away from the clamping cylinder (11), and it can press the adjusting washer (121) onto the second outer inclined cone surface (32).

3. The clamping fixture for machining thin-walled cylindrical parts according to claim 2, characterized in that, The clamping cylinder (11) is coaxially fixed with a guide cylinder (13) at the end near the connecting sleeve (1221); the adjusting washer (121) is coaxially fixed with a positioning cylinder (14) at the end near the clamping cylinder (11); the positioning cylinder (14) is placed in the inner cavity of the connecting sleeve (1221) and can be axially slidably sleeved on the outer wall of the guide cylinder (13).

4. The clamping fixture for machining thin-walled cylindrical parts according to claim 2, characterized in that, The adjusting washer (121) is formed by circumferentially splicing multiple arc-shaped parts.

5. A clamping fixture for machining thin-walled cylindrical parts according to any one of claims 1-4, characterized in that, The first engagement structure (112) is an external thread, and the second engagement structure (12211) is an internal thread that is threadedly connected to the external thread.

6. A processing method for thin-walled cylindrical parts, comprising the following steps: S10. Rough turning of inner and outer cavities: The blank is clamped with a general-purpose chuck, and the inner and outer cavities are turned to remove the blank allowance. S11. Stabilization heat treatment: Using an air furnace, the temperature is heated to 90℃~120℃, held for 12h~14h, and then air-cooled with the furnace to achieve dimensional stabilization treatment, reducing workpiece deformation and stress corrosion tendency. S12. Semi-finish turning of inner and outer cavities: When machining the outer cavity, use a two-center clamping fixture to clamp the workpiece, and leave a finishing allowance of 0.1 mm to 0.15 mm on the surface and thread outer diameter; when machining the inner cavity, use a clamping fixture for machining thin-walled cylindrical parts as described in any one of claims 1-5 to clamp the workpiece, and leave a finishing allowance of 0.15 mm to 0.2 mm. S13. Cyclic stabilization treatment: The workpiece is subjected to cyclic cold and heat treatment to stabilize gradient and stress changes, accelerate the metal recovery process, and form a more stable dislocation structure, thereby achieving long-term stability of part dimensions. S14. Precision machining of inner and outer cavities: The workpiece is clamped using the clamping method in S12, and both the inner and outer cavities of the workpiece are machined to the dimensions shown in the drawing.

7. The thin-walled cylindrical component processing technology according to claim 6, characterized in that, In S12, the step of clamping the workpiece using a clamping fixture for machining thin-walled cylindrical parts as described in any one of claims 1-5 includes the following steps: S121. Install the clamping cylinder (11): Clamp the clamping cylinder (11) on the chuck and align the axis runout; S122. Install the workpiece: Place the thin-walled cylindrical part (3) to be processed on one side corresponding to its first end (33) into the inner cavity of the clamping cylinder (11) to ensure that the first outer oblique cone surface (31) on the thin-walled cylindrical part (3) fits against the first inner oblique cone surface (111) on the clamping cylinder (11). S123, Install the locking ring (12): Install the locking ring (12) on the thin-walled cylindrical part (3) so that its second inner inclined cone surface (1211) fits against the second outer inclined cone surface (32) of the thin-walled cylindrical part (3) to be processed; S124, Locking ring (12) locking: A hydraulic center frame (2) is set at the second end (34) of the thin-walled cylindrical part (3) and the hydraulic center frame (2) is clamped on the outer wall surface of the thin-walled cylindrical part (3) corresponding to its second end (34). After aligning the axis, the second engagement structure (12211) of the locking ring (122) is engaged and locked with the first engagement structure (112) on the clamping cylinder (11) to complete the clamping work.

8. The thin-walled cylindrical component processing technology according to claim 6, characterized in that, In S13, the cyclical cold and heat treatment of the workpiece includes: S131. Clean the dirt, residual metal shavings and oil stains on the surface of the parts with a cleaning agent and dry them; S132. Reduce the workpiece temperature to -170℃~-195℃, hold for 1 hour, and then air cool with the furnace. S133. After the frost on the surface of the parts melts, heat it to 90℃~120℃ and hold it for 1h~2h, then air cool it with the furnace. S134. Repeat steps S132-S133 to perform cold and hot cycle treatment, with no less than 2 cold and hot cycles.

9. A thin-walled cylindrical component processing technology according to any one of claims 6-8, characterized in that, It also includes S15, surface treatment: electrochemical oxidation treatment of the surface of the finished workpiece, wherein the inner cavity is hard anodized and the remaining surfaces are chromic acid anodized.

10. The thin-walled cylindrical component processing technology according to claim 9, characterized in that, It also includes S16, grinding the inner cavity: manually grinding the inner cavity of the workpiece to improve the morphological quality of the inner cavity.

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