Inner supporting tool for trimming cylinder port

Abstract

According to the inner diameter size requirement of a machined cylindrical part, the reasonable conicity of a sliding section of a linkage sliding block and the reasonable outer diameter of a boss of an elastic shaft sleeve are designed, and forward and backward movement of a structure with the working face of the outer contour face of the linkage sliding block being a conical face is achieved through screwing and loosening of threads. And the elastic shaft sleeve which is tightly matched with the elastic shaft sleeve and is provided with an inner conical surface and an elastic batten is expanded and contracted, so that the cylindrical part with the wall thickness being less than or equal to 3.0 mm is supported to perform port trimming processing. Due to the fact that the tool is high in precision, effective supporting within the full-circumference size range of the inner molded surface of the cylindrical part can be achieved after one-time adjustment, operation is easy, the alignment precision of the cylindrical part is high, the machining efficiency of the cylindrical part is improved, the machining precision is high, and the consistency and reliability of the machining size of the cylindrical part are improved.

Description

Technical Field

[0001] This invention relates to the machinery manufacturing industry, specifically to an internal support fixture for turning the end of a cylindrical tube with a wall thickness ≤3mm and a diameter ≤φ200mm. Background Technology

[0002] A certain thin-walled cylindrical component is used in welding assembly with other parts. At the same time, there are strict requirements for the welding quality of the thin-walled cylindrical component. The machining accuracy of the welding bevel at the end of the cylindrical component has a significant impact on the welding quality.

[0003] This cylindrical part is formed by spinning. The inner diameter of the cylinder is φ130mm, the wall thickness is 2.5mm, and the total length of the cylinder is 1550mm. The design drawings require that welding bevels be machined at both ends of the cylinder, with a bevel angle of 45° and a bevel blunt edge dimension of 1mm.

[0004] A common method for clamping thin-walled cylindrical parts using internal supports involves manually adjusting several screws on a ring-shaped steel forging to achieve clamping and alignment before machining. However, this method is extremely inconvenient for thin-walled cylinders with a diameter less than φ200mm, as the manual adjustment space of the internal support is too small. Furthermore, the adjustment of each nut is not equidistant, resulting in non-uniform elastic deformation of the cylinder's inner wall. Consequently, the amount of material removed at the cylinder's end during machining is uneven, and the resulting bevel edge does not adequately meet design requirements.

[0005] Patent CN106271354B discloses an automatic centering internal support, a multi-block automatic centering adjustable structure. A retractable screw structure is installed in a guide groove on the circumferential surface of a guide ring. During operation, the movement of the screw simultaneously extends and retracts all the supporting blocks, ensuring the positioning center remains constant and achieving automatic centering, guaranteeing that the cylinder or shell becomes rounded while being supported. However, this invention contains 17 different parts, nearly 50 in total, including various transmission methods such as sliding, worm gear transmission, gear transmission, and bearing transmission, which are prone to transmission failure. The support has high production and maintenance costs and is unsuitable for small-batch, multi-variety production. This invention, however, also has an automatic centering function, contains only 5 parts, and has lower production and maintenance costs.

[0006] The invention disclosed in CN107984278A is a mandrel support device for cylindrical workpieces. The radial movement of the mandrel support device's top rod and top block assembly is achieved through the length adjustment of multiple length-adjusting rods. Support is achieved when the top block assembly abuts against the inner wall of the cylindrical workpiece. This invention is suitable for large-sized cylindrical workpieces and improves the adaptability of the mandrel support device. However, this invention still requires manual adjustment of the lengths of each adjusting rod to achieve good support, and the lengths of the adjusting rods are not adjusted at equal intervals, resulting in low adjustment efficiency and low cutting accuracy at the cylindrical end.

[0007] The invention disclosed in application number 201920098704.5 is an internal support fixture for circumferential welding of cylindrical components. It achieves multi-point internal support for the circumferential seam of the cylindrical component by sliding and extending a long support rod at a slotted position on the outer side of an arc plate, facilitating welding. This type of multi-block self-centering adjustable structural support fixture uses a similar telescopic screw structure to radially adjust multiple circumferentially distributed blocks, enabling pre-tightening and alignment of the internal support. However, the adjustment of this type of fixture is time-consuming and labor-intensive, and the adjustment of each block is relatively independent, resulting in poor consistency. Excessive or insufficient gaps between the blocks affect the adjustment accuracy. Furthermore, because the layout of this screw structure requires a certain amount of space, this type of self-centering adjustable structural support fixture is generally unsuitable for machining edges of cylindrical parts with a diameter ≤ φ200mm. Summary of the Invention

[0008] To overcome the shortcomings of low processing accuracy and low efficiency in the existing technology, this invention proposes an inner support for cutting the end of a cylinder.

[0009] This invention includes a mandrel, a pull ring nut, a linkage slider, and an elastic bushing. The pull ring nut is fitted onto the external thread of the mandrel near its center; the linkage slider is fitted onto the mandrel and axially linked with the pull ring nut via a snap plate on the pull ring nut, and the inner hole of the linkage slider is clearance-fitted with the mandrel; the large end face of the elastic bushing is fitted onto the linkage slider through a tapered hole, and the other end is fixed to the mandrel.

[0010] The mandrel is a two-stage stepped shaft. The small-diameter section at one end of the mandrel is a mounting section that mates with the lathe chuck. The large-diameter section is divided into an external thread section and a smooth section. The length of the external thread section is L1, and there is a through hole in the middle of the smooth section.

[0011] The linkage slider is divided into three sections: a flange section, a middle section, and a sliding section. The inner hole of the linkage slider is a through hole that slides with the large-diameter section of the mandrel. The flange structure of the flange section forms a clearance fit with the two snap plates of the pull ring nut. The linkage slider and the pull ring nut are connected through the flange structure and the snap plates to achieve axial synchronous forward or backward movement of the linkage slider and the pull ring nut. The middle section of the linkage slider is a cylindrical section with a wall thickness of t = 5 mm. The middle section is provided with symmetrical pin relief grooves with a length of L2, where L2 = δ2 / tanθ + k. The outer surface of the sliding section of the linkage slider is a conical surface with a taper of θ = 10 to 15° and an axial length of L3 = 25 to 30 mm.

[0012] The elastic bushing is divided into an elastic section and a fixed section. The elastic section is divided into multiple evenly distributed elastic strips along the axial direction. The axial length of the elastic strips is determined according to the length that the cylindrical part needs to support. The elastic section of the bushing is composed of the strips. The fixed section has a through hole with a diameter of φ1 = 10 mm.

[0013] The width of the elastic strip is b = 6 mm.

[0014] The inner surface of the pull ring nut is a threaded surface that mates with the external threaded section of the mandrel. The length of the threaded surface of the pull ring nut is L4 = 30-35mm. Two retaining plates are symmetrically distributed on the end face of the large diameter end. A U-shaped retaining groove is formed between the retaining plates and the end face.

[0015] The outer end of the elastic segment has radially and circumferentially protruding bosses. When the elastic segment of the sleeve is divided into multiple elastic strips, the bosses form workpiece support blocks at the outer ends of each elastic strip.

[0016] The outer diameter D1 of the boss is slightly smaller than the inner diameter D of the cylindrical part, so that a gap δ is formed between the two, δ=D / 200mm; the distance between the side surfaces of two adjacent bosses is d, d=2~5mm; the inner surface of the boss is an inward conical surface, the taper is the same as the taper of the sliding section of the linkage slider, and the axial length of the conical surface is L5=35~40mm.

[0017] The outer diameter of the boss is D1 = D - 2δ mm.

[0018] The tail of the pin is a hemispherical head, and there is an annular elastic retaining groove on the circumference of one end of the head; the distance from the axial width symmetrical plane of the elastic retaining groove to the end face is 3mm.

[0019] The length of the external thread of the mandrel is L1 = L4 + δ / tanθ + k, where k is the safety distance, k = 10 mm; δ is the gap between the outer diameter D1 of the boss and the inner diameter D of the cylindrical part; θ is the taper of the outer surface of the sliding section of the linkage slider; and L4 is the length of the threaded surface of the pull ring nut.

[0020] The length of the pin clearance groove is L2 = δ / tanθ + k.

[0021] During operation, rotating the pull ring nut causes it and the linkage slider to move forward together on the shaft, making the outer surface of the tapered section of the linkage slider fit tightly against the inner tapered surface of the elastic bushing. As it continues to move forward, the sliding of the fitting tapered surface opens up the multiple elastic protrusions evenly distributed on the sleeve, causing each elastic protrusion to open outward synchronously and uniformly, so that the outer surface of each elastic protrusion fits against the inner surface of the cylindrical part to be machined and trimmed, thereby achieving effective support for the inner wall of the cylindrical part.

[0022] After the machining of the cylindrical part is completed, the pull ring nut is turned to move backward, causing the inner surface of the elastic bushing to separate from the outer conical surface of the pull ring nut, and causing each of the elastic bosses to contract, thereby causing the outer surface of the elastic bosses to separate from the inner wall of the machined cylindrical part, thus achieving unloading.

[0023] Based on the required inner diameter of the processed cylindrical part, this invention designs a reasonable taper of the sliding section of the linkage slider and the outer diameter of the elastic bushing boss. In use, the outer surface of the elastic bushing boss in its initial free state has a certain gap δ with the inner wall of the cylindrical part. By applying torque to the blind hole or groove on the outer circumferential surface of the pull ring nut, the pull ring nut and the linkage slider move forward on the mandrel, approaching the elastic bushing. At this time, the outer surface of the linkage slider and the inner surface of the elastic bushing are tightly fitted through the tapered surface. When the forward movement continues, the sliding of the fitted tapered surface opens up the multiple evenly distributed elastic strips on the elastic bushing. The multiple evenly distributed elastic strips open outwards uniformly and synchronously. The boss on its outer surface effectively supports the inner wall of the cylindrical part; the cylindrical part is machined and trimmed according to size and precision requirements; after machining, a reverse torque is applied to the pull ring nut, and the pull ring nut and the linkage slider move backward on the mandrel. The conical surface on the outer surface of the linkage slider disengages from the conical surface on the inner surface of the elastic bushing, and the multiple elastic strips evenly distributed on the elastic bushing contract. The boss on the outer surface of the elastic bushing disengages from the inner wall of the machined cylindrical part, thus achieving unloading; disassemble the cylinder; disassemble the tooling, and apply anti-rust oil for protection and maintenance.

[0024] This invention achieves forward and backward movement of the structure with a conical working surface on the outer contour of the linkage slider by tightening and loosening the threads. This movement, in turn, is facilitated by the opening and closing of the elastic bushing with an inner conical surface and elastic strip that closely cooperate with the slider, thus supporting the end-edge cutting of cylindrical parts with a wall thickness ≤3.0mm. Due to the high precision of this fixture, effective support can be achieved across the entire circumference of the cylindrical part's inner surface after a single adjustment. The operation is simple, and the high alignment accuracy of the cylindrical part improves machining efficiency and ensures high processing precision.

[0025] This invention combines the advantages of a multi-top block automatic centering adjustable structure and a circumferentially segmented adjustable internal support structure. For cylindrical parts with a diameter ≤ φ200mm, it features simple operation and high processing accuracy, improving the consistency and reliability of the machining dimensions of cylindrical parts.

[0026] This invention enables efficient machining and trimming of cylindrical parts on CNC lathes. After a single adjustment, it provides effective support for the entire circumferential dimensions of the cylindrical part's inner surface. The operation is simple, quick, and offers high alignment accuracy. It achieves high efficiency and precision in machining and trimming cylindrical parts, and is characterized by its simple structure, convenient operation, and high efficiency.

[0027] This invention is applicable to the machining and trimming of cylindrical parts with a diameter ≤ φ200mm. It effectively supports the inner wall of the cylindrical part through the contraction and expansion of elastic strips. Compared with existing technologies, the beneficial effects of this invention are:

[0028] 1. This invention can achieve effective support within the entire circumferential dimension of the inner surface of the cylindrical part after a single adjustment. It is a semi-automatic operation that is simple, fast, and efficient, effectively reducing the labor intensity of workers.

[0029] 2. During alignment, this invention only requires minor adjustments by turning the structure to achieve effective support of the tooling for the inner surface of the cylindrical part, and ensures the alignment accuracy of the cylindrical part. Due to the better effective support of the inner surface of the cylindrical part and the increased alignment accuracy of the tooling and the cylindrical part, the cylindrical part experiences less vibration and no tool chatter during machining, resulting in higher machining efficiency. After edge trimming, the perpendicularity of the cylindrical part's end face and the dimensional accuracy of multiple quadrants are also higher, with smaller deviations.

[0030] Taking a cylinder with an outer diameter of φ180±0.5mm, a wall thickness of 2.5±0.1mm, and a length of 1300±0.5mm after end trimming as an example, using the tooling of this invention, the processing time is 9min15s-9min45s, with an average processing time of 9min32s. However, using the multi-block automatic centering tooling, the processing time is 12min35s-13min30s, with an average processing time of 13min, resulting in an improvement in processing efficiency of approximately 26.7%. Statistical analysis of the four-quadrant lengths of products processed by the two types of internal supports shows that the tooling used in this invention exhibits smaller deviations in four-quadrant lengths and higher end face perpendicularity.

[0031] Table 1. Statistics on machining time for a cylinder of a certain size.

[0032]

[0033]

[0034] Table 2. Statistics on processing time for a cylinder of a certain size.

[0035] Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the structure of the present invention.

[0037] Figure 2 This is an isometric view of the present invention.

[0038] Figure 3 This is a schematic diagram of the mandrel structure.

[0039] Figure 4 This is a structural schematic diagram of a pull ring nut; where: 4a is the front view, 4b is the AA section view of 4a, and 4c is the right view of the pull ring nut.

[0040] Figure 5 This is a schematic diagram of the linkage slider; where 5a is the main view and 5b is the sectional view of 5a.

[0041] Figure 6 This is a structural schematic diagram of the elastic bushing; where: 6a is the front view, 6b is the right view, and 6c is the CC section view of 6b.

[0042] Figure 7 This is a schematic diagram of the pin structure of the present invention.

[0043] In the diagram: 1. Mandrel; 2. Pull ring nut; 3. Linkage slider; 4. Elastic bushing; 5. Pin. Detailed Implementation

[0044] This embodiment is an internal support for machining and trimming cylindrical parts with a wall thickness ≤3mm.

[0045] The elastic bushing 4 is made of spring steel, specifically 65Mn in this embodiment. The spindle 1, pull ring nut 2, linkage slider 3, and pin 5 are made of 45# steel.

[0046] The mandrel 1 is a two-stage stepped shaft. The small-diameter section at one end of the mandrel is the mounting section that mates with the lathe chuck. The large-diameter section is divided into an external thread section and a smooth section. The external thread section is threadedly engaged with the pull ring nut 2. The length of the external thread of the mandrel is L1. The smooth section is clearance-fitted with the linkage slider 3. The middle part of the smooth section contains a through hole for a fixing pin 5.

[0047] The pull ring nut 2 is fitted onto the external thread near the center of the mandrel; the linkage slider 3 is fitted onto the mandrel 1, and the pull ring nut and the linkage slider are axially linked through a snap plate on the pull ring nut, and the inner hole of the linkage slider is clearance-fitted with the mandrel. The large end face of the elastic bushing 4 is fitted onto the linkage slider through a tapered hole, and the other end is fixed to the mandrel by a pin; tool holes and tool slots are evenly distributed on the outer circumferential surface of the pull ring nut for easy mounting. By applying torque to the tool hole or tool slot with a tool, the pull ring nut is rotated, so that the pull ring nut and the linkage slider move forward or backward together along the mandrel.

[0048] The linkage slider 3 is divided into three sections: a flange section, a middle section, and a mushroom-shaped sliding section. The inner hole of the linkage slider is a through hole that slides with the large-diameter section of the mandrel. The flange structure of the flange section forms a clearance fit with the two snap plates of the pull ring nut. The linkage slider and the pull ring nut are connected through the flange structure and the snap plates to achieve axial synchronous forward or backward movement of the linkage slider and the pull ring nut. The middle section of the linkage slider is a cylindrical section with a wall thickness of t = 5 mm. The middle section is provided with symmetrical pin avoidance grooves. The function of the grooves is to avoid interference between the linkage slider and the pin passing through the mandrel when it moves forward or backward on the mandrel. The length of the groove is L2 and the width is b1 = 11 mm. The outer surface of the sliding section of the linkage slider is a conical surface with a taper of θ = 10~15° and an axial length of L3 = 25~30 mm.

[0049] The middle section of the linkage slider is a cylindrical section with a wall thickness of t = 5 mm. The middle section is provided with symmetrical pin clearance grooves with a length of L2. The outer surface of the sliding section of the linkage slider is a conical surface with a taper of θ = 10 to 15° and an axial length of L3 = 25 to 30 mm.

[0050] The inner surface of the pull ring nut is a threaded surface that mates with the mandrel, and the length of the threaded surface is L4 = 30-35mm. The outer circumferential surface of the pull ring nut has four tool holes and tool slots evenly distributed. Torque is applied to these tool holes and tool slots using a tool to rotate the pull ring nut, allowing it to move forward or backward around the mandrel. Near the large-diameter end of the pull ring nut on the mandrel, there are two retaining plates. These two retaining plates and the flange section of the linkage slider are clearance-fitted, with a clearance value of δ1 = 0.2mm. This clearance fit ensures that when the pull ring nut rotates forward or backward around the mandrel, the linkage slider only moves forward or backward without rotating.

[0051] The elastic bushing is divided into an elastic section and a fixed section. The elastic section is axially divided into six evenly distributed elastic strips, each with a width of b = 6 mm. The axial length of each elastic strip is determined based on the length the cylindrical component needs to support. These strips form the elastic section of the bushing. The outer end of each elastic section has radially and circumferentially protruding bosses. When the elastic section of the bushing is divided into multiple elastic strips, the bosses form workpiece support blocks at the outer ends of each elastic strip. The outer diameter D1 of these bosses is slightly smaller than the inner diameter D of the cylindrical component, forming a gap δ, where δ = D / 200 mm. The distance between the side surfaces of two adjacent bosses is d, where d = 2–5 mm. The inner surface of these bosses is an inwardly tapered surface with the same taper as the sliding surface of the linkage slider. The axial length of the tapered surface is L5 = 35–40 mm. The outer diameter D1 of the boss is determined using the formula D1 = D - 2δ mm.

[0052] The fixed section has a through hole with a diameter of φ1 = 10 mm.

[0053] The pin has a diameter of φ2 = 10 mm, a hemispherical head with a diameter of φ3 = 14 mm at the tail, and a groove with a depth of 1 mm at a distance of 3 mm from the end face at the head. The pin passes through the elastic sleeve and the mandrel, and is secured by an elastic baffle at the groove, thus fixing the elastic sleeve to the mandrel.

[0054] In this invention, the gap δ between the boss and the cylindrical part is determined based on the inner diameter D of the processed cylindrical part, and the outer diameter D1 of the boss is determined based on the gap δ, the length L4 of the threaded surface of the pull ring nut, and the taper θ of the outer surface of the sliding section of the linkage slider.

[0055] In this example, the inner diameter D of the cylindrical part is φ200mm, the length L4 of the threaded surface of the pull ring nut is 30mm, and the outer surface taper θ of the sliding section of the linkage slider is 10°. The tooling is designed and manufactured.

[0056] δ = D / 1000 = 200 / 200 = 1;

[0057] The gap δ between the boss and the cylindrical part is 1mm;

[0058] D1=D-2δ=200-2×1=198;

[0059] The outer diameter D1 of the elastic bushing boss is 198mm;

[0060] L1=L4+δ / tanθ+k=30+1 / tan10°+10≈45.7;

[0061] The length L1 of the external thread on the mandrel is 45.7 mm;

[0062] L2=δ / tanθ+k=1 / tan10°+10≈15.7;

[0063] The length L2 of the pin clearance groove is 15.7mm.

[0064] During installation, the assembled inner support is mounted on the lathe chuck of the CNC lathe via a shaft, and the runout of the working surface of the inner support is aligned to be no more than 0.05mm. The cylindrical part with an inner diameter of φ200mm to be machined is then fitted onto the inner support, and the installation position of the cylindrical part is adjusted to ensure that the cutting edge does not interfere with the inner support during machining, thus avoiding damage to the inner support.

[0065] In use, in the initial free state, there is a gap δ between the outer protrusion of the elastic bushing and the inner wall of the cylindrical part. In this embodiment, the gap is 1mm. Rotating the pull ring nut causes the pull ring nut and the linkage slider to move forward on the shaft together, so that the outer surface of the tapered section of the linkage slider is in close contact with the inner tapered surface of the elastic bushing. When moving forward, the sliding of the contacting tapered surface opens up the multiple elastic protrusions evenly distributed on the sleeve, so that each elastic protrusion opens outward synchronously and evenly, and the outer surface of each elastic protrusion is in contact with the inner surface of the cylindrical part to be machined and trimmed, thereby achieving effective support for the inner wall of the cylindrical part.

[0066] After the machining of the cylindrical part is completed, the pull ring nut is turned to move backward, causing the inner surface of the elastic bushing to separate from the outer conical surface of the pull ring nut, and causing each of the elastic bosses to contract, thereby causing the outer surface of the elastic bosses to separate from the inner wall of the machined cylindrical part, thus achieving unloading.

Claims

1. An internal support for machining and trimming cylindrical parts with a wall thickness ≤ 3mm, characterized in that, It includes a mandrel, a pull ring nut, a linkage slider, and an elastic bushing; the pull ring nut is fitted onto the external thread of the mandrel near the middle part; the linkage slider is fitted onto the mandrel and the pull ring nut and the linkage slider are axially linked through a buckle plate on the pull ring nut, and the inner hole of the linkage slider is clearance-fitted with the mandrel; the large end face of the elastic bushing is fitted onto the linkage slider through a tapered hole, and the other end is fixed to the mandrel.

2. The internal support for machining and trimming cylindrical parts with a wall thickness ≤ 3mm as described in claim 1, characterized in that, The mandrel is a two-stage stepped shaft. The small-diameter section at one end of the mandrel is a mounting section that mates with the lathe chuck. The large-diameter section is divided into an external thread section and a smooth section. The length of the external thread section is L1, and there is a through hole in the middle of the smooth section.

3. The internal support for machining and trimming cylindrical parts with a wall thickness ≤ 3mm as described in claim 1, characterized in that, The linkage slider is divided into three sections: a flange section, a middle section, and a sliding section. The inner hole of the linkage slider is a through hole that slides with the large-diameter section of the mandrel. The flange structure of the flange section forms a clearance fit with the two snap plates of the pull ring nut. The linkage slider and the pull ring nut are connected through the flange structure and the snap plates to achieve axial synchronous forward or backward movement of the linkage slider and the pull ring nut. The middle section of the linkage slider is a cylindrical section with a wall thickness of t = 5 mm. The middle section is provided with symmetrical pin relief grooves. The length of the pin relief grooves is L2, where L2 = δ2 / tanθ + k. The outer surface of the sliding section of the linkage slider is a conical surface with a taper of θ = 10 to 15° and an axial length of L3 = 25 to 30 mm.

4. The internal support for machining and trimming cylindrical parts with a wall thickness ≤ 3mm as described in claim 1, characterized in that, The elastic bushing is divided into an elastic section and a fixed section. The elastic section is divided into multiple evenly distributed elastic strips along the axial direction. The axial length of the elastic strips is determined according to the length that the cylindrical part needs to support. The elastic section of the bushing is composed of the strips. The fixed section has a through hole with a diameter of φ1 = 10 mm.

5. The internal support for machining and trimming cylindrical parts with a wall thickness ≤ 3mm as described in claim 3, characterized in that, The width of the elastic strip is b = 6 mm.

6. The internal support for machining and trimming cylindrical parts with a wall thickness ≤ 3mm as described in claim 1, characterized in that, The inner surface of the pull ring nut is a threaded surface that mates with the external threaded section of the mandrel. The length of the threaded surface is L4 = 30-35mm. Two retaining plates are symmetrically distributed on the end face of the large diameter end. A U-shaped retaining groove is formed between the retaining plates and the end face.

7. The internal support for machining and trimming cylindrical parts with a wall thickness ≤ 3mm as described in claim 1, characterized in that, The outer end of the elastic segment has radially and circumferentially protruding bosses. When the elastic segment of the sleeve is divided into multiple elastic strips, the bosses form workpiece support blocks at the outer ends of each elastic strip. The outer diameter D1 of the boss is slightly smaller than the inner diameter D of the cylindrical part, so that a gap δ is formed between the two, δ = D / 200mm; the distance between the side surfaces of two adjacent bosses is d, d = 2~5mm; the inner surface of the boss is an inward conical surface, the taper of which is the same as the taper of the sliding section of the linkage slider, and the axial length of the conical surface is L5 = 35~40mm. The outer diameter of the boss is D1 = D - 2δ mm.

8. The internal support for machining and trimming cylindrical parts with a wall thickness ≤ 3mm as described in claim 1, characterized in that, The tail of the pin is a hemispherical head, and there is an annular elastic retaining groove on the circumference of one end of the head; the distance from the axial width symmetrical plane of the elastic retaining groove to the end face is 3mm.

9. The internal support for machining and trimming cylindrical parts with a wall thickness ≤ 3mm as described in claim 1, characterized in that, During operation, rotating the pull ring nut causes the pull ring nut and the linkage slider to move forward on the shaft together, making the outer surface of the tapered section of the linkage slider fit tightly against the inner tapered surface of the elastic bushing. As it continues to move forward, the sliding of the fitting tapered surface opens up the multiple elastic protrusions evenly distributed on the sleeve, causing each elastic protrusion to open outward synchronously and evenly, so that the outer surface of each elastic protrusion fits against the inner surface of the cylindrical part to be machined and trimmed, thereby achieving effective support for the inner wall of the cylindrical part. After the machining of the cylindrical part is completed, the pull ring nut is turned to move backward, causing the inner surface of the elastic bushing to separate from the outer conical surface of the pull ring nut, and causing each of the elastic bosses to contract, thereby causing the outer surface of the elastic bosses to separate from the inner wall of the machined cylindrical part, thus achieving unloading.

10. The internal support for machining and trimming cylindrical parts with a wall thickness ≤ 3mm as described in claim 1, characterized in that, The length of the external thread of the mandrel is L1 = L4 + δ / tanθ + k, where k is the safety distance, k = 10 mm; δ is the gap between the outer diameter D1 of the boss and the inner diameter D of the cylindrical part; θ is the taper of the outer surface of the sliding section of the linkage slider; and L4 is the length of the thread surface of the pull ring nut.

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