Manufacturing method and clamp for weak-rigidity thin-wall long-cylinder parts

Abstract

This invention provides a manufacturing method for weakly rigid thin-walled cylindrical parts, aiming to solve the problems of these parts being unable to withstand axial clamping forces, prone to vibration and deformation during machining, and unable to guarantee dimensional and positional accuracy. This invention relates to the field of machining and employs an annular groove machining method in the manufacturing process of turning the right end inner hole annular groove in both directions, turning the machine back and precision turning the left end of the inner hole, turning the left end inner hole annular groove in both directions, turning the outer circle annular groove in both directions, and precision turning both end faces. This method effectively reduces the cutting force during annular groove machining, solves the problem of large deformation during turning of the inner and outer circles of weakly rigid thin-walled cylindrical parts, ultimately improves machining efficiency, ensures machining quality, and meets the more stringent precision requirements of high-precision weakly rigid thin-walled cylindrical parts.

Description

Technical Field

[0001] This invention relates to the field of machining, and in particular to a method for manufacturing thin-walled long cylindrical parts with weak rigidity and a fixture thereof. Background Technology

[0002] Thin-walled long cylindrical parts are widely used in high-end manufacturing fields such as power generation equipment and aerospace. Their thin walls give them significant advantages such as light weight and high material utilization, but also bring a series of processing challenges, including high machining difficulty, susceptibility to vibration, and easy deformation. In particular, ensuring the dimensional and positional accuracy of the parts becomes especially difficult under the combined effects of multiple factors such as cutting force, internal stress, clamping force, and cutting heat.

[0003] Currently, common methods for machining thin-walled parts include soft chuck clamping, mandrel clamping, and elastic expansion clamping. However, these methods are mostly suitable for short thin-walled parts with relatively low requirements for dimensional and positional accuracy. For high-precision, weakly rigid thin-walled cylindrical parts with intersecting annular grooves on their inner and outer circles, existing machining methods and corresponding tooling fixtures are insufficient to meet their stringent accuracy requirements. This is mainly because these parts have complex structures, cannot withstand axial clamping forces, have high dimensional and positional accuracy requirements, and are sensitive to cutting forces and vibrations. Therefore, new machining technologies and methods are needed to improve the machining accuracy and efficiency of these parts. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a manufacturing method and fixture for weakly rigid thin-walled long cylindrical parts. It mainly solves the problems that weakly rigid thin-walled long cylindrical parts cannot withstand axial clamping force, are prone to vibration and deformation during processing, and cannot guarantee the dimensional and positional accuracy of the parts. It improves processing efficiency and ensures processing quality, and can meet the more stringent precision requirements of high-precision weakly rigid thin-walled long cylindrical parts.

[0005] To achieve the purpose of this invention, the technical solution adopted is as follows: A method for manufacturing weakly rigid thin-walled long cylindrical parts, such as Figure 2 , 3 As shown in 7.13, the specific processing flow is as follows: (1) Cutting according to the outer circle of the process reference: The outer circle of the process reference includes the middle outer circle and the outer circles of the two steps of the process part 202. The thickness of the step is set to 1.5~2mm. The outer circle of the step is 1mm larger than the outer circle of the part. This design avoids the flexible solid part of the part and provides an axial rigid clamping part, which effectively avoids the part clamping deformation. (2) Drilling; (3) Rough turn the outer circle according to the process reference: leave a 3mm allowance for the inner and outer circles and the total length; (4) Natural aging: After rough machining, the parts are left to stand naturally for 48 to 72 hours to remove the internal stress generated by rough machining; (5) According to the process reference, the outer circle is semi-finished: leave a 0.5mm allowance on the outer circle, a 1.5mm allowance on the inner hole, and a 0.5mm allowance on the total length; (6) Natural aging: Place the semi-finished parts naturally for 48 to 72 hours to remove the internal stress generated by the semi-finishing process; (7) Finish turning the outer circle of the process reference: The two transition centers 201 are used to clamp the inner conical surfaces of the two ends of the process part 202 respectively. The outer circle of the process reference in the middle is finished. The two-step process reference outer circle is machined in both directions to effectively ensure that the three process reference outer circles are coaxial, avoid deformation of the process reference outer circle, and ensure that the process part 202 is smoothly loaded into the inner hole turning fixture. (8) Use an internal turning fixture to finish turn the right end of the internal hole: use long soft jaws to hold the outer surface of the left end of the mounting base 4, and the center support supports the W position of the right end of the mounting base 4 so that the mounting base 4 bears the clamping force, effectively reducing the deformation of the part affected by the clamping force, and making the clamping of the part more reliable. (9) Turning the inner hole annular groove in both directions: Using two inner hole turning tools with a tool tip angle of 35°, the inner hole annular groove is turned by point contact in the forward and reverse feed method, which effectively reduces the cutting force and solves the problem of large cutting force when the inner hole grooving tool cuts the inner hole annular groove, which leads to deformation of weak rigid thin-walled long cylindrical parts. (10) Turning around and precision turning the left end of the inner hole: Turning around and clamping the outer surface of the right end of the mounting base 4, the center frame supports the W position of the left end of the mounting base 4, and precision turning the left end of the inner hole. By turning around and aligning the left and right ends with the inner hole, the problem of not being able to process ultra-long, weakly rigid, thin-walled cylindrical parts due to the limitations of tool length and machine tool processing range is solved. (11) Turning the inner hole annular groove in both directions: Using two inner hole turning tools with a tool tip angle of 35°, the inner hole annular groove is turned by point contact in the forward and reverse feed method, which effectively reduces the cutting force and solves the problem of large cutting force when the inner hole grooving tool cuts the inner hole annular groove, which leads to deformation of weak rigid thin-walled long cylindrical parts. (12) Use an external turning fixture to finish turning the outer diameter: Use double center clamping to finish turning the outer diameter, which effectively ensures the coaxiality of the inner and outer diameters of the part; (13) Turning the outer annular groove in both directions: The innovative use of the left and right lateral cutting tools with a tool tip angle of 35° to turn the outer annular groove by point contact in both directions effectively reduces the cutting force and solves the problem of large cutting force when the outer grooving tool cuts the outer annular groove, which leads to deformation of weak rigid thin-walled long cylindrical parts. (14) Finishing both ends: Using a double-center clamping method, the left and right ends are finished by using an outer circle left and right offset cutter with a cutter tip angle of 35°, which effectively ensures the end face runout requirements.

[0006] As a preferred option, the internal turning fixture for realizing the manufacturing method of weakly rigid thin-walled long cylindrical parts is: (1) such as Figure 3 , 4 As shown in Figures 5 and 6, the mounting base 4 of the internal turning fixture is designed as a cylindrical shape with a thickness of 25-30mm to ensure that the mounting base 4 has high rigidity and effectively prevent the clamping force from being transmitted to the part and causing clamping deformation. The mounting base 4 has external threads 10 at both ends, which cooperate with the internal threads 31 of the locking nut 1 to press the stepped surface of the process part 202 with the surface 32, so that the part bearing the clamping force is offset from the flexible solid part of the part, forming an axial rigid clamping and preventing the part from being deformed by the clamping force. (2) Multiple symmetrical screw holes 11 for mounting damping pins 3 are evenly distributed on the outer circle 13 of the mounting base 4, providing multiple symmetrical and uniform damping support points within the length of the part, forming a circumferential point contact damping clamping structure, which effectively eliminates the internal hole cutting vibration. (3) Multiple annular grooves 12 corresponding to screw holes 11 are provided in the inner hole 16 of the mounting base 4 to avoid burrs at the hole opening that prevent the parts from being installed and to ensure the fit accuracy of the parts in the inner hole of the mounting base 4; W parts for center support are provided at the left and right ends, which is conducive to turning the left and right ends to the inner hole of the car and solving the problem that the ultra-long weak rigid thin-walled long cylindrical parts cannot be processed due to the limitation of tool length and machine tool processing range. (4) The outer circle 13 of the mounting base 4 is coaxial with the inner hole 16 and perpendicular to the two end faces 14, which helps to improve the accuracy of the part turning and correction and ensure the shape accuracy of the inner hole of the part to the rear of the vehicle; the left and right ends of the inner hole 16 are provided with guide cone surfaces 15 to ensure smooth loading and unloading of the parts and avoid deformation of the parts during installation. (5) The right end of the vibration damping pin 3 is made of steel, with an internal hexagonal head 23 on the end face and external threads 22 that mate with the mounting base screw hole 11. A T-head 21 is provided in the middle to effectively prevent the support vibration damping head 20 from falling off after tightening and loosening. The support vibration damping head 20 at the left end of the vibration damping pin 3 is made of polyurethane material and is integrally cast, making the joint tighter and effectively preventing damage to the surface of the parts. It has a significant effect in absorbing cutting vibration. (6) The process part 202 is installed in the inner hole turning fixture. Its two ends extend 0.5-1mm beyond the end face of the locking nut 1, which facilitates the semi-finishing turning of the two ends of the part and leaves an accurate allowance for the total length of the finish turning, which helps to ensure the accurate position of the inner hole groove of the part.

[0007] As a preferred external turning fixture for realizing the manufacturing method of weakly rigid thin-walled long cylindrical parts: (1) such as Figure 7 , 8 As shown in Figures 9, 10, 11, and 12, the structural elements at both ends of the mandrel 43 are symmetrically distributed. A symmetrical conical surface 53 is set along the center of symmetry 52, which cooperates with the inner conical surface 64 of the elastic expansion sleeve 45. The inner conical surface 64, in turn, cooperates with the conical surface 71 of the tapered pressure block 42. The contact area of ​​the conical surfaces is more than 80%. By tightening the locking nuts 47 installed on the external threads 55 at both ends of the mandrel, the tapered pressure block 42 is driven to move axially on the reference outer circle 54 of the mandrel. The bidirectional conical surface cooperation opens the elastic expansion sleeve 45, thereby tightening the part. This ensures full contact tightening of the inner surface of the weak rigid thin-walled long cylindrical part, and the tightening force is more uniform, effectively improving the dimensional and positional accuracy of the part. (2) The left and right ends of the mandrel 43 are provided with reference center holes 40, whose axis is coaxial with the outer circle axis 50 and 54 and coaxial with the axis of the conical surface 53, which effectively ensures the positional accuracy of the parts and the repeatability of the positioning accuracy during batch processing; (3) Eight symmetrical slits 60 are evenly distributed on the elastic expansion sleeve 45, and the length of the unslit end is 25-35mm, so that the elastic expansion sleeve has sufficient elasticity, ensuring the expansion amount and elastic recovery of the elastic expansion sleeve, and making the tightening of the parts more powerful. (4) The axis of the inner conical surface 64 at both ends of the elastic expansion sleeve 45 is coaxial with the axis of the outer circle 61 and the axis of the inner hole 63, which effectively ensures the positional accuracy of the parts; (5) The outer circle 61 of the elastic expansion sleeve 45 is clearance fit with the inner hole of the part, with a clearance of 0.05 to 0.1 mm; the inner hole 63 is clearance fit with the outer circle 54 of the mandrel 43, with a clearance of 0.01 to 0.02 mm; this helps to ensure the coaxiality and end face runout requirements of the parts. (6) The right end of the tapered block 42 is provided with a groove 76 and an outer circle 74 that mates with the inner hole step 82 of the left end of the semi-open transmission body 41, so as to ensure that the semi-open transmission body 41 can be inserted into the right end of the tapered block 42; the hexagonal screw 46 is used to connect the threaded hole 81 of the semi-open transmission body 41 through the six countersunk holes 92 of the locking nut 47 to lock the semi-open transmission body 41; when the locking nut is rotated forward, it drives the semi-open transmission body to push the surface 73 of the tapered block 42, so that the tapered block moves forward axially; when the locking nut is rotated backward, it drives the semi-open transmission body to pull the surface 75 of the tapered block 42, so that the tapered block moves backward axially; this facilitates the smooth and quick installation and disassembly of parts, and avoids deformation of weak rigid thin-walled long cylindrical parts during installation and disassembly. (7) The outer circle 72 of the tapered pressure block 42 is clearance fit with the inner hole of the part, and the inner hole 77 is clearance fit with the outer circle 54 of the spindle 43. The clearance is 0.01 to 0.02 mm, which provides precision fit support for the left and right ends of the part, and further ensures the coaxiality and end face runout requirements of the part. (8) The semi-open transmission body 41 is set in two halves, which is conducive to the semi-open transmission body 41 being inserted into the right end of the tapered pressure block 42. (9) When the inner hole of the part is precision machined and installed in the external turning fixture, its two end faces extend 0.5 to 1 mm beyond the end face of the locking nut 42, which facilitates the precision machining of the two end faces to ensure the total length and helps to ensure the positional accuracy of the end face of the part. (10) The maximum outer diameter of the locking nut 47 is equal to the maximum outer diameter of the semi-open transmission body 41, and is 1-2 mm smaller than the inner hole of the part. This provides a retraction position for precision turning of the end face, which helps to ensure the integrity of both end faces of the part and avoids interference between the tool and the fixture.

[0008] The above technical solution has the following beneficial effects: 1. Manufacturing Method for Weakly Rigid Thin-Walled Long Cylindrical Parts: Based on the structural and precision requirements of weakly rigid thin-walled long cylindrical parts, the proposed process flow is as follows: blanking, drilling, rough turning, natural aging, semi-finish turning, natural aging, finish turning the outer diameter of the process datum, finish turning the right end of the inner hole, turning the annular groove of the right end inner hole in both directions, turning the inner hole to the left end in both directions, turning the outer diameter to the left end, turning the outer diameter annular groove in both directions, and finish turning both end faces. In this manufacturing process, a novel process arrangement and machining method for the annular groove are proposed, effectively reducing the cutting force during annular groove machining, solving the problem of large deformation of the inner and outer diameters during turning of weakly rigid thin-walled long cylindrical parts, and effectively ensuring part quality.

[0009] 2. Internal Hole Turning Fixture: The innovative design of the circumferential point contact vibration damping clamping structure provides multiple symmetrical and uniform vibration damping support points within the length range of the part, effectively eliminating internal hole cutting vibration; combined with the outer circle of the process datum, it staggers the flexible solid parts of the part, forming axial rigid clamping, effectively reducing internal hole machining deformation, and ensuring the dimensional and shape accuracy of the internal hole of the weak rigid thin-walled long cylindrical part.

[0010] 3. External Cylindrical Turning Fixture: An innovative bidirectional symmetrical mandrel expansion structure is designed. The structural elements at both ends of the mandrel are symmetrically distributed. Tightening the locking nuts at both ends moves the tapered pressure blocks, utilizing the bidirectional tapered surface to expand the elastic sleeve, thereby expanding the part. This ensures full contact expansion of the inner surface of weakly rigid, thin-walled, long cylindrical parts, resulting in more uniform expansion force and effectively improving the dimensional and positional accuracy of the parts. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of a weakly rigid, thin-walled, long cylindrical component. Figure 2 Flowchart for machining weakly rigid thin-walled long cylindrical parts; Figure 3 This is a schematic diagram of the overall structure of an internal turning fixture; Figure 4This is a schematic diagram of the installation base structure; Figure 5 This is a half-section diagram of the lock nut; Figure 6 This is a schematic diagram of a vibration damping pin structure; Figure 7 This is a schematic diagram of the overall structure of the external turning fixture; Figure 8 This is a schematic diagram of the mandrel structure; Figure 9 This is a schematic diagram of an elastic expansion sleeve structure; Figure 10 This is a schematic diagram of the tapered pressure block structure; Figure 11 Schematic diagram of a semi-open transmission body; Figure 12 Schematic diagram of the locking nut structure; Figure 13 Schematic diagram of the finishing of the outer circle of the process datum; In the diagram: 1-Locking nut, 2-Semi-finished part, 3-Vibration damping pin, 4-Mounting base, 41-Semi-open transmission body, 42-Tapered pressure block, 43-Mandrel, 45-Elastic expansion sleeve, 46-Screw, 47-Locking nut, 10-External thread, 11-Symmetrical threaded hole, 12-Annular groove, 13-Outer circle, 14-Two end faces, 15-Guide cone surface, 16-Inner hole, 20-Vibration damping head, 21-T-head, 22-Thread, 23-Internal hexagon, 30, 31-Internal thread 32-Surface, 40-Reference center hole, 50-Outer circle axis, 52-Symmetry center, 53-Conical surface, 54-Outer circle, 55-External thread, 60-Symmetrical slit, 61-Outer circle, 63-Inner hole, 64-Inner hole conical surface, 71-Conical surface, 72-Outer circle, 73-Surface, 74-Outer circle, 75-Surface, 76-Groove, 77-Inner hole, 81-Threaded hole, 82-Inner hole step, 92-Counterhead, 201-Transition center, 202-Process part. Detailed Implementation

[0012] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0013] Example 1 A method for manufacturing weakly rigid thin-walled long cylindrical parts, such as Figure 2 , 3 As shown in 7.13, the specific processing flow is as follows: (1) Cutting according to the outer circle of the process reference: The outer circle of the process reference includes the middle outer circle and the outer circles of the two steps of the process part 202. The thickness of the step is set to 1.5~2mm. The outer circle of the step is 1mm larger than the outer circle of the part. This design avoids the flexible solid part of the part and provides an axial rigid clamping part, which effectively avoids the part clamping deformation. (2) Drilling; (3) Rough turn the outer circle according to the process reference: leave a 3mm allowance for the inner and outer circles and the total length; (4) Natural aging: After rough machining, the parts are left to stand naturally for 48 to 72 hours to remove the internal stress generated by rough machining; (5) According to the process reference, the outer circle is semi-finished: leave a 0.5mm allowance on the outer circle, a 1.5mm allowance on the inner hole, and a 0.5mm allowance on the total length; (6) Natural aging: Place the semi-finished parts naturally for 48 to 72 hours to remove the internal stress generated by the semi-finishing process; (7) Finish turning the outer circle of the process reference: The two transition centers 201 are used to clamp the inner conical surfaces of the two ends of the process part 202 respectively. The outer circle of the process reference in the middle is finished. The two-step process reference outer circle is machined in both directions to effectively ensure that the three process reference outer circles are coaxial, avoid deformation of the process reference outer circle, and ensure that the process part 202 is smoothly loaded into the inner hole turning fixture. (8) Use an internal turning fixture to finish turn the right end of the internal hole: use long soft jaws to hold the outer surface of the left end of the mounting base 4, and the center support supports the W position of the right end of the mounting base 4 so that the mounting base 4 bears the clamping force, effectively reducing the deformation of the part affected by the clamping force, and making the clamping of the part more reliable. (9) Turning the inner hole annular groove in both directions: Using two inner hole turning tools with a tool tip angle of 35°, the inner hole annular groove is turned by point contact in the forward and reverse feed method, which effectively reduces the cutting force and solves the problem of large cutting force when the inner hole grooving tool cuts the inner hole annular groove, which leads to deformation of weak rigid thin-walled long cylindrical parts. (10) Turning around and precision turning the left end of the inner hole: Turning around and clamping the outer surface of the right end of the mounting base 4, the center frame supports the W position of the left end of the mounting base 4, and precision turning the left end of the inner hole. By turning around and aligning the left and right ends with the inner hole, the problem of not being able to process ultra-long, weakly rigid, thin-walled cylindrical parts due to the limitations of tool length and machine tool processing range is solved. (11) Turning the inner hole annular groove in both directions: Using two inner hole turning tools with a tool tip angle of 35°, the inner hole annular groove is turned by point contact in the forward and reverse feed method, which effectively reduces the cutting force and solves the problem of large cutting force when the inner hole grooving tool cuts the inner hole annular groove, which leads to deformation of weak rigid thin-walled long cylindrical parts. (12) Use an external turning fixture to finish turning the outer diameter: Use double center clamping to finish turning the outer diameter, which effectively ensures the coaxiality of the inner and outer diameters of the part; (13) Turning the outer annular groove in both directions: The innovative use of the left and right lateral cutting tools with a tool tip angle of 35° to turn the outer annular groove by point contact in both directions effectively reduces the cutting force and solves the problem of large cutting force when the outer grooving tool cuts the outer annular groove, which leads to deformation of weak rigid thin-walled long cylindrical parts. (14) Finishing both ends: Using a double-center clamping method, the left and right ends are finished by using an outer circle left and right offset cutter with a cutter tip angle of 35°, which effectively ensures the end face runout requirements.

[0014] Example 2 An internal turning fixture for manufacturing weakly rigid thin-walled long cylindrical parts: (1) such as Figure 3 , 4 As shown in Figures 5 and 6, the mounting base 4 of the internal turning fixture is designed as a cylindrical shape with a thickness of 25-30mm to ensure that the mounting base 4 has high rigidity and effectively prevent the clamping force from being transmitted to the part and causing clamping deformation. The mounting base 4 has external threads 10 at both ends, which cooperate with the internal threads 31 of the locking nut 1 to press the stepped surface of the process part 202 with the surface 32, so that the part bearing the clamping force is offset from the flexible solid part of the part, forming an axial rigid clamping and preventing the part from being deformed by the clamping force. (2) Multiple symmetrical screw holes 11 for mounting damping pins 3 are evenly distributed on the outer circle 13 of the mounting base 4, providing multiple symmetrical and uniform damping support points within the length of the part, forming a circumferential point contact damping clamping structure, which effectively eliminates the internal hole cutting vibration. (3) Multiple annular grooves 12 corresponding to screw holes 11 are provided in the inner hole 16 of the mounting base 4 to avoid burrs at the hole opening that prevent the parts from being installed and to ensure the fit accuracy of the parts in the inner hole of the mounting base 4; W parts for center support are provided at the left and right ends, which is conducive to turning the left and right ends to the inner hole of the car and solving the problem that the ultra-long weak rigid thin-walled long cylindrical parts cannot be processed due to the limitation of tool length and machine tool processing range. (4) The outer circle 13 of the mounting base 4 is coaxial with the inner hole 16 and perpendicular to the two end faces 14, which helps to improve the accuracy of the part turning and correction and ensure the shape accuracy of the inner hole of the part to the rear of the vehicle; the left and right ends of the inner hole 16 are provided with guide cone surfaces 15 to ensure smooth loading and unloading of the parts and avoid deformation of the parts during installation. (5) The right end of the vibration damping pin 3 is made of steel, with an internal hexagonal head 23 on the end face and external threads 22 that mate with the mounting base screw hole 11. A T-head 21 is provided in the middle to effectively prevent the support vibration damping head 20 from falling off after tightening and loosening. The support vibration damping head 20 at the left end of the vibration damping pin 3 is made of polyurethane material and is integrally cast, making the joint tighter and effectively preventing damage to the surface of the parts. It has a significant effect in absorbing cutting vibration. (6) The process part 202 is installed in the inner hole turning fixture. Its two ends extend 0.5-1mm beyond the end face of the locking nut 1, which facilitates the semi-finishing turning of the two ends of the part and leaves an accurate allowance for the total length of the finish turning, which helps to ensure the accurate position of the inner hole groove of the part.

[0015] Example 3 An external turning fixture for manufacturing weakly rigid thin-walled long cylindrical parts: (1) such as Figure 7 , 8 As shown in Figures 9, 10, 11, and 12, the structural elements at both ends of the mandrel 43 are symmetrically distributed. A symmetrical conical surface 53 is set along the center of symmetry 52, which cooperates with the inner conical surface 64 of the elastic expansion sleeve 45. The inner conical surface 64, in turn, cooperates with the conical surface 71 of the tapered pressure block 42. The contact area of ​​the conical surfaces is more than 80%. By tightening the locking nuts 47 installed on the external threads 55 at both ends of the mandrel, the tapered pressure block 42 is driven to move axially on the reference outer circle 54 of the mandrel. The bidirectional conical surface cooperation opens the elastic expansion sleeve 45, thereby tightening the part. This ensures full contact tightening of the inner surface of the weak rigid thin-walled long cylindrical part, and the tightening force is more uniform, effectively improving the dimensional and positional accuracy of the part. (2) The left and right ends of the mandrel 43 are provided with reference center holes 40, whose axis is coaxial with the outer circle axis 50 and 54 and coaxial with the axis of the conical surface 53, which effectively ensures the positional accuracy of the parts and the repeatability of the positioning accuracy during batch processing; (3) Eight symmetrical slits 60 are evenly distributed on the elastic expansion sleeve 45, and the length of the unslit end is 25-35mm, so that the elastic expansion sleeve has sufficient elasticity, ensuring the expansion amount and elastic recovery of the elastic expansion sleeve, and making the tightening of the parts more powerful. (4) The axis of the inner conical surface 64 at both ends of the elastic expansion sleeve 45 is coaxial with the axis of the outer circle 61 and the axis of the inner hole 63, which effectively ensures the positional accuracy of the parts; (5) The outer circle 61 of the elastic expansion sleeve 45 is clearance fit with the inner hole of the part, with a clearance of 0.05 to 0.1 mm; the inner hole 63 is clearance fit with the outer circle 54 of the mandrel 43, with a clearance of 0.01 to 0.02 mm; this helps to ensure the coaxiality and end face runout requirements of the parts. (6) The right end of the tapered block 42 is provided with a groove 76 and an outer circle 74 that mates with the inner hole step 82 of the left end of the semi-open transmission body 41, so as to ensure that the semi-open transmission body 41 can be inserted into the right end of the tapered block 42; the hexagonal screw 46 is used to connect the threaded hole 81 of the semi-open transmission body 41 through the six countersunk holes 92 of the locking nut 47 to lock the semi-open transmission body 41; when the locking nut is rotated forward, it drives the semi-open transmission body to push the surface 73 of the tapered block 42, so that the tapered block moves forward axially; when the locking nut is rotated backward, it drives the semi-open transmission body to pull the surface 75 of the tapered block 42, so that the tapered block moves backward axially; this facilitates the smooth and quick installation and disassembly of parts, and avoids deformation of weak rigid thin-walled long cylindrical parts during installation and disassembly. (7) The outer circle 72 of the tapered pressure block 42 is clearance fit with the inner hole of the part, and the inner hole 77 is clearance fit with the outer circle 54 of the spindle 43. The clearance is 0.01 to 0.02 mm, which provides precision fit support for the left and right ends of the part, and further ensures the coaxiality and end face runout requirements of the part. (8) The semi-open transmission body 41 is set in two halves, which is conducive to the semi-open transmission body 41 being inserted into the right end of the tapered pressure block 42. (9) When the inner hole of the part is precision machined and installed in the external turning fixture, its two end faces extend 0.5 to 1 mm beyond the end face of the locking nut 42, which facilitates the precision machining of the two end faces to ensure the total length and helps to ensure the positional accuracy of the end face of the part. (10) The maximum outer diameter of the locking nut 47 is equal to the maximum outer diameter of the semi-open transmission body 41, and is 1-2 mm smaller than the inner hole of the part. This provides a retraction position for precision turning of the end face, which helps to ensure the integrity of both end faces of the part and avoids interference between the tool and the fixture.

[0016] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for manufacturing a weakly rigid, thin-walled, long cylindrical part, characterized in that, Includes the following steps: (1) Cutting material according to the outer circle of the process reference: The outer circle of the process reference includes the middle outer circle and the outer circles of the two steps of the process part (202). The thickness of the step is set to 1.5~2mm, and the outer circle of the step is 1mm larger than the outer circle of the part. (2) Drilling; (3) Rough turn the outer circle according to the process reference: leave a 3mm allowance for the inner and outer circles and the total length; (4) Natural aging: After rough machining, the parts are left to stand naturally for 48 to 72 hours to remove the internal stress generated by rough machining; (5) According to the process reference, the outer circle is semi-finished: leave a 0.5mm allowance on the outer circle, a 1.5mm allowance on the inner hole, and a 0.5mm allowance on the total length; (6) Natural aging: Place the semi-finished parts naturally for 48 to 72 hours to remove the internal stress generated by the semi-finishing process; (7) Finish turning the outer circle of the process reference: Using two transition centers (201) to hold the inner conical surfaces of the two ends of the process part (202) respectively, finish turning the outer circle of the process reference in the middle, and turning the two-step outer circle of the process reference in both directions to make the three outer circles of the process reference coaxial. (8) Use an internal turning fixture to finish turn the right end of the internal hole: The mounting base (4) of the internal turning fixture is set in the shape of a cylindrical body. The left and right ends of the mounting base (4) are provided with external threads (10) to cooperate with the internal threads (31) of the locking nut (1) to press the stepped surface of the process part (202) with the surface (32); the outer circle (13) of the mounting base (4) is evenly distributed with symmetrical screw holes (11), and the vibration damping pins (3) are installed in the symmetrical screw holes (11); the vibration damping head (20) of one end of the vibration damping pin (3) is made of polyurethane material and is integrally cast; through the circumferential point contact vibration damping clamping structure, multiple symmetrical and uniform vibration damping support points are provided within the length range of the part; the left end outer surface of the mounting base (4) is clamped by long soft claws, and the center frame supports the W position of the right end of the mounting base (4); (9) Turning the inner hole annular groove on the right end in both directions: Use two inner hole turning tools with a tool tip angle of 35° to turn the inner hole annular groove by point contact in both directions. (10) Turn around and finish the left end of the inner hole: Turn around and clamp the outer surface of the right end of the mounting base (4), the center frame supports the W position of the left end of the mounting base (4), and finish the left end of the inner hole; (11) Turn the annular groove of the inner hole on the left end in both directions; use two internal turning tools with a tool tip angle of 35° to turn the annular groove of the inner hole by point contact in both directions. (12) Use an external turning fixture to finish turning the outer circle: Use double center clamping to finish turning the outer circle; the structural elements of the mandrel (43) of the external turning fixture are symmetrically distributed at both ends, and a symmetrical conical surface (53) is set along the center of symmetry (52), which cooperates with the inner conical surface (64) of one end of the elastic expansion sleeve (45). The inner conical surface (64) of the other end of the elastic expansion sleeve (45) cooperates with the conical surface (71) of the tapered pressure block (42). By tightening the locking nuts (47) installed on the external threads (55) at both ends of the mandrel (43) in opposite directions, the tapered pressure block (42) is driven to move axially on the reference outer circle (54) of the mandrel (43). The bidirectional conical surface cooperation is used to open the elastic expansion sleeve (45) and tighten the part. (13) Turning the outer annular groove in both directions: Use a left and right eccentric tool with a tool tip angle of 35° to turn the outer annular groove by point contact in both directions. (14) Finish turning of both ends: Using a double-center clamping method, finish turning the left and right ends with an outer circle left and right offset cutter with a cutter tip angle of 35°.

2. The method for manufacturing weakly rigid thin-walled long cylindrical parts according to claim 1, characterized in that: The mounting base of the inner hole turning fixture described in step (8) has a thickness of 25-30 mm; the inner hole (16) of the mounting base (4) is provided with an annular groove (12) corresponding to the screw hole (11); the left and right ends of the mounting base (4) are provided with W parts for center support; the outer circle (13) of the mounting base (4) is coaxial with the inner hole (16) and perpendicular to the two end faces (14); the left and right ends of the inner hole (16) are provided with guide cone surfaces (15); the process part (202) is installed in the inner hole turning fixture, and its two end faces extend 0.5-1 mm beyond the end face of the locking nut (1).

3. The method for manufacturing weakly rigid thin-walled long cylindrical parts according to claim 1, characterized in that: The other end of the vibration damping pin (3) is made of steel, with an internal hexagon (23) on the end face, and a thread (22) on the outside to cooperate with the mounting base screw hole (11). A T-head (21) is provided in the middle.

4. The method for manufacturing weakly rigid thin-walled long cylindrical parts according to claim 1, characterized in that: The mandrel (43) of the external turning fixture described in step (12) has reference center holes (40) at both ends, the axis of which is coaxial with the axis of the outer circle and with the axis of the conical surface (53); the elastic expansion sleeve (45) has 8 symmetrical slits (60) evenly distributed, and the length of the unslit end is 25-35mm; the axis of the conical surface (64) of the inner hole at both ends of the elastic expansion sleeve (45) is coaxial with the axis of the outer circle (61) and with the axis of the inner hole (63); the outer circle (61) of the elastic expansion sleeve (45) and the inner hole of the part are in clearance fit. The gap is 0.05-0.1mm; the inner hole (63) and the outer circle (54) of the mandrel (43) are in clearance fit, with a fit gap of 0.01-0.02mm; the right end of the tapered pressure block (42) is provided with a groove (76) and an outer circle (74) that mates with the inner hole step (82) of the left end of the semi-open transmission body (41), ensuring that the semi-open transmission body (41) can be inserted into the right end of the tapered pressure block (42); the screw of the semi-open transmission body (41) is connected by an internal hexagonal screw (46) through the six countersunk holes (92) of the locking nut (47). The hole (81) locks the half-open transmission body (41); when the locking nut (47) is turned forward, it drives the half-open transmission body (41) to push the surface (73) of the tapered pressure block (42), causing the tapered pressure block (42) to move forward axially; when the locking nut (47) is turned backward, it drives the half-open transmission body (41) to pull the surface (75) of the tapered pressure block (42), causing the tapered pressure block (42) to move backward axially; the outer circle (72) of the tapered pressure block (42) and the inner hole of the part are in clearance fit, and the inner hole (77) of the tapered pressure block (42) and the core The outer circle (54) of the shaft (43) is a clearance fit with a clearance of 0.01 to 0.02 mm. The semi-open transmission body (41) is set in two halves so that the semi-open transmission body (41) is inserted into the right end of the tapered pressure block (42). When the inner hole of the part is precision machined and installed in the outer diameter turning fixture, its two end faces extend 0.5 to 1 mm beyond the end face of the tapered pressure block (42). The maximum outer circle of the locking nut (47) is equal to the maximum outer circle of the semi-open transmission body (41) and is 1 to 2 mm smaller than the inner hole of the part, providing a retraction position for precision turning of the end face.

5. The method for manufacturing weakly rigid thin-walled long cylindrical parts according to claim 1, characterized in that: The internal turning tools mentioned in step (9) are two tools with a 35° tip angle, one in front and one in back.

6. The method for manufacturing weakly rigid thin-walled long cylindrical parts according to claim 1, characterized in that: The internal turning tools mentioned in step (11) are two tools with a 35° tip angle, one in front and one in back.

7. The method for manufacturing weakly rigid thin-walled long cylindrical parts according to claim 1, characterized in that: The tip angle of the outer circle left and right deflecting cutters mentioned in step (13) is 35°.

8. The method for manufacturing weakly rigid thin-walled long cylindrical parts according to claim 1, characterized in that: The tip angle of the outer circle left and right deflecting cutters mentioned in step (14) is 35°.

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