Machining method for improving precision of dimensional form and location tolerance of inner wall of hole of steel plate cylinder part

Abstract

The invention discloses a machining method for improving the dimensional form and location tolerance precision of the inner wall of a hole of a steel plate cylinder part, and relates to the technical field of motors, and the machining method comprises the following machining steps: S1, carrying out radial plastic deformation expansion shaping on a steel plate cylinder through a bulging machine with staggered teeth on a bulging mould petal, the plastic deformation radial expansion amount calculation formula is delta d = 1.2 d delta t / E; s2, after relevant parts are welded to the outer wall of the steel plate cylinder, the steel plate cylinder is fixed to a vibration aging platform through a pneumatic clamping jaw to be subjected to vibration aging treatment, and internal stress of the steel plate cylinder is removed; s3, the steel plate cylinder is subjected to radial elastic deformation expansion shaping through a bulging machine without staggered teeth on the bulging mould petals; and S4, shot blasting treatment is conducted on the surface of the steel plate cylinder, and surface dirt and an oxide layer are removed. When the machining method is used for manufacturing the steel plate cylinder part for the motor, machine tool cutting machining is avoided, materials, labor and time are saved, and operation is fast and convenient.

Description

Technical Field

[0001] The invention relates to the technical field of motors, and in particular to a processing method for improving the shape and position tolerance accuracy of the inner wall size of a steel plate cylindrical part hole. Background Art

[0002] At present, both seamless steel pipes and welded steel pipes have large inner diameter tolerances, and large roundness and cylindricity tolerances. In order to obtain high-precision dimensions of the inner wall of round pipe parts, the inner wall of steel pipe cylinder parts is generally turned, bored, machined or extruded (spherical or hemispherical) by core tire.

[0003] If machine tool cutting is used to improve the dimensional tolerance and geometric tolerance of the inner wall hole, the following problems will arise:

[0004] 1. It is difficult to machine and clamp thin-walled round tubes, and they are prone to rebound and deformation after machining;

[0005] 2. When the length of the cylinder is long, the boring and cutting processing time is also long. The greater the inner diameter deviation of the original cylinder, the greater the cutting amount, resulting in waste materials and wasted time, and high manufacturing costs. If the inner wall of the cylinder is extruded and shaped by a core tire, (spherical, hemispherical) is squeezed from one end of the inner hole of the round tube to the other end of the round tube under external pressure;

[0006] like Figures 11 to 14 As mentioned above, when the core tire is extruded and shaped to improve the size accuracy of the inner wall hole of the cylinder, harmful force P3 is inevitable, and this stress state runs through the process of the core tire passing through the inner hole of the cylindrical part. Therefore, this is not a method suitable for the shaping of thin-walled cylindrical parts, which can easily cause the size tolerance of the inner hole of the workpiece after extrusion to be extremely unstable or to have greater deformation. Summary of the invention

[0007] The object of the present invention is to provide a processing method for improving the shape and position tolerance accuracy of the inner wall size of a steel plate cylindrical part hole, so as to solve the above-mentioned defects caused by the prior art.

[0008] A processing method for improving the shape and position tolerance accuracy of the inner wall size of a steel plate cylindrical part hole, comprising the following processing steps:

[0009] S1: The steel plate cylinder is subjected to radial plastic deformation expansion and shaping by a bulging machine with staggered teeth on the bulging die. The radial expansion amount of plastic deformation is calculated by the formula:

[0010] ▽d=1.2d δt / E;

[0011] in:

[0012] d: inner diameter of cylinder (mm);

[0013] ▽d: plastic deformation expansion (mm);

[0014] Δt: Internal stress of cylinder when internal pressure is applied (kg / cm 2 );

[0015] E: elastic modulus (kg / cm 2 );

[0016] S2: After the relevant parts are welded on the outer wall of the steel plate cylinder, the steel plate cylinder is fixed on the vibration aging platform with a pneumatic clamp to perform vibration aging treatment to remove the internal stress of the steel plate cylinder;

[0017] S3: radial elastic deformation expansion and shaping of the steel plate cylinder is performed by a bulging machine without staggered teeth on the bulging die;

[0018] S4: Shot peening is performed on the surface of the steel plate cylinder to remove surface dirt and oxide layer.

[0019] Preferably, the bulging machine comprises a mold template, a support frame, a bulging mold flap, a bulging mold core, a lifting plate and a hydraulic cylinder, the mold template is horizontally mounted on the upper side of the support frame, and is evenly connected to a plurality of supporting legs on the lower side of the support frame, a circular mounting groove is centrally provided on the upper surface of the mold template, and a circular through hole is centrally provided at the bottom of the mounting groove, a circular mounting plate is coaxially connected in the mounting groove, and a plurality of sliding plates in a circular array are slidably connected to the upper side of the mounting plate, the bulging mold flap is provided with a plurality of correspondingly connected Connected to the upper side of each sliding plate, the inner wall surface of the expansion mold flap is a beveled surface, the expansion mold core is coaxially inserted in the through hole, the outer wall surface of the expansion mold core is an inclined conical surface, and the inclined conical surface of the expansion mold core is in sliding contact with the beveled surface of the expansion mold flap, the tire mold template is connected to an inverted L-shaped mounting block on the outer side of each sliding plate, the inner side of the mounting block is horizontally connected to a mounting plate, and the lower surface of the mounting plate is in sliding contact with the upper surface of the sliding plate, and the hydraulic cylinder is arranged below the tire mold template and drives the expansion mold core to rise and fall.

[0020] Preferably, two pairs of guide pillars are symmetrically connected to the lower side of the tire mold template, each guide pillar is slidably connected to a guide sleeve, the lifting plate is horizontally connected between all the guide sleeves, the lower end of the tire expansion mold core is fixed to the center of the lifting plate by a pair of locking nuts, the hydraulic cylinder is vertically installed upward at the lower ends of all the guide pillars, and a connecting plate is coaxially connected to the end of its piston rod by a pair of locking nuts, and a number of connecting rods in a circular array are connected between the connecting plate and the lifting plate.

[0021] Preferably, a pair of mounting holes are symmetrically provided at the lower portion of the mounting block, and a compression spring is slidably connected in the mounting holes, and the inner end of the compression spring abuts against the side of the sliding plate, and the mounting block is connected to a blocking plate at the outer end of the pair of mounting holes.

[0022] Preferably, the upper surface of the mounting plate is evenly distributed with oil grooves 1, the upper surface of the sliding plate is distributed with oil grooves 2, and the upper surface of the mounting block is provided with oil holes 2 communicating with the oil grooves 2.

[0023] Preferably, the oblique conical surface of the tire expanding mold core is evenly distributed with three oil grooves, the upper end surface of the tire expanding mold core is centrally provided with a circular oil storage groove, and a dust cover is detachably connected to the upper side of the oil storage groove.

[0024] Preferably, a limiting sleeve is sleeved on the piston rod of the hydraulic cylinder between the connecting plate and the cylinder barrel.

[0025] Preferably, the number of the inflation mold halves is eight, and the outer wall surface of the inflation mold core is an oblique cone surface divided into eight equal parts.

[0026] Preferably, two rows of staggered teeth are symmetrically provided on both sides of the tire expanding mold halves, and a staggered opening is formed between two adjacent staggered teeth, and the staggered teeth on the tire expanding mold halves are correspondingly inserted into the staggered openings of adjacent tire expanding mold halves.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] 1. The present invention avoids machine tool cutting when manufacturing steel plate cylindrical parts for motors, thus saving materials, labor and time, and being quick to operate;

[0029] 2. When manufacturing the steel plate cylindrical part for the motor, the inner diameter dimensional accuracy of the steel plate cylindrical part reaches H8-H9, and the inner wall cylindricity of the steel plate cylindrical part is less than 0.06 mm;

[0030] 3. When the fan-shaped expansion mold with staggered teeth of the present invention radially expands the inner wall of the steel plate cylindrical part, the external force P applied by the hydraulic cylinder to the expansion mold core acts on the outer wall surface of the eight expansion mold pieces through the conical inclined surface, and the inner wall of the steel plate cylindrical part is uniformly expanded radially through the eight expansion mold pieces. The expansion force stretches the steel plate to exceed the yield point of the steel plate itself, causing the steel plate cylindrical part to undergo permanent plastic deformation to ensure the geometric shape stability of the steel plate cylindrical part. After considering the material rebound factor, the expansion amount that stretches the material beyond the yield point can ensure the inner diameter dimensional accuracy of the steel plate cylindrical part. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the overall three-dimensional structure of the present invention.

[0032] Figure 2 It is a schematic structural diagram of the overall front view of the present invention.

[0033] Figure 3 It is a structural schematic diagram of a local three-dimensional first viewing angle of the present invention.

[0034] Figure 4 It is a structural schematic diagram of a local three-dimensional second viewing angle of the present invention.

[0035] Figure 5 It is a structural schematic diagram of the mold template and the mounting plate in the present invention.

[0036] Figure 6 It is a schematic structural diagram of the tire expansion mold halves with staggered teeth in the present invention.

[0037] Figure 7 It is a structural schematic diagram of the sliding plate and the mounting block in the present invention.

[0038] Figure 8 It is a schematic structural diagram of the tire expansion mold core and the dust cover in the present invention.

[0039] Fig. 9 It is a schematic diagram of the structure of the shaping device including the tire expansion mold half without staggered teeth.

[0040] Fig.10 for Fig. 9 Schematic diagram of the structure of the tire expansion mold half without staggered teeth.

[0041] Fig.11 It is a schematic diagram of the structure of a steel plate cylinder that is extruded and shaped using a conical core.

[0042] Fig.12 It is a schematic diagram of the force applied to a steel plate cylinder when extruded and shaped using a conical core.

[0043] Fig.13 It is a schematic diagram of the structure of a steel plate cylinder that is extruded and shaped using a spherical core.

[0044] Fig.14 This is a schematic diagram of the forces acting on a steel plate cylinder extruded and shaped using a spherical core.

[0045] in:

[0046] 101-tire mold template; 101a-installation groove; 101b-through hole; 102-support frame; 103-support foot; 104-installation plate; 104a-oil groove 1; 105-sliding plate; 105a-oil groove 2; 106-tire expansion mold flap; 1061-staggered teeth; 106a-staggered mouth; 107-tire expansion mold core; 107a-oil groove 3; 107b-oil storage tank; 107c- Oil hole one; 108-dust cover; 109-mounting block; 109a-mounting hole; 109b-oil hole two; 110-mounting plate; 111-compression spring; 112-blocking plate; 113-guide column; 114-guide sleeve; 115-lifting plate; 116-locking nut one; 117-hydraulic cylinder; 118-locking nut two; 119-connecting plate; 120-connecting rod; 121-limiting sleeve. DETAILED DESCRIPTION

[0047] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0048] like Figures 1 to 14 As shown, a processing method for improving the shape and position tolerance accuracy of the inner wall of the hole of a steel plate cylindrical part includes the following processing steps:

[0049] S1: The steel plate cylinder is subjected to radial plastic deformation expansion and shaping by a bulging machine with staggered teeth 1061 on the bulging die 106, wherein the radial expansion amount of the plastic deformation is calculated by the formula:

[0050] ▽d=1.2d δt / E;

[0051] in:

[0052] d: inner diameter of cylinder (mm);

[0053] ▽d: plastic deformation expansion (mm);

[0054] Δt: Internal stress of cylinder when internal pressure is applied (kg / cm 2 );

[0055] E: elastic modulus (kg / cm 2 );

[0056] S2: After the relevant parts are welded on the outer wall of the steel plate cylinder, the steel plate cylinder is fixed on the vibration aging platform with a pneumatic clamp to perform vibration aging treatment to remove the internal stress of the steel plate cylinder;

[0057] S3: radially elastically deforming and expanding the steel plate cylinder by using a bulging machine without staggered teeth 1061 on the bulging mold 106;

[0058] S4: Shot peening is performed on the surface of the steel plate cylinder to remove surface dirt and oxide layer.

[0059] In this embodiment, the bulging machine includes a tire mold template 101, a support frame 102, a bulging mold flap 106, a bulging mold core 107, a lifting plate 115 and a hydraulic cylinder 117. The tire mold template 101 is horizontally installed on the upper side of the support frame 102, and a plurality of supporting legs 103 are evenly connected to the lower side of the support frame 102. A circular mounting groove 101a is centrally provided on the upper surface of the tire mold template 101, and a circular through hole 101b is centrally provided at the bottom of the mounting groove 101a. A circular mounting plate 104 is coaxially connected in the mounting groove 101a, and a plurality of sliding plates 105 in a circular array are slidably connected to the upper side of the mounting plate 104. The bulging mold flap 106 is provided with a plurality of supporting legs 103. The tire mold template 101 is connected to the upper side of each sliding plate 105, and the inner wall surface of the tire expansion mold flap 106 is a beveled surface. The tire expansion mold core 107 is coaxially inserted in the through hole 101b. The outer wall surface of the tire expansion mold core 107 is an inclined conical surface, and the inclined conical surface of the tire expansion mold core 107 is in sliding contact with the beveled surface of the tire expansion mold flap 106. The tire mold template 101 is connected to an inverted L-shaped mounting block 109 on the outer side of each sliding plate 105, and the inner side of the mounting block 109 is horizontally connected to a mounting plate 110, and the lower surface of the mounting plate 110 is in sliding contact with the upper surface of the sliding plate 105. The hydraulic cylinder 117 is arranged below the tire mold template 101 and drives the tire expansion mold core 107 to rise and fall.

[0060] In this embodiment, two pairs of guide posts 113 are symmetrically connected to the lower side of the mold template 101, and a guide sleeve 114 is slidably connected to each guide post 113. The lifting plate 115 is horizontally connected between all the guide sleeves 114. The lower end of the bulging mold core 107 is fixed to the center of the lifting plate 115 through a pair of locking nuts 116. The hydraulic cylinder 117 is vertically installed on the lower ends of all the guide posts 113, and a connecting plate 119 is coaxially connected to the end of its piston rod through a pair of locking nuts 2 118, and a plurality of connecting rods 120 in a circular array are connected between the connecting plate 119 and the lifting plate 115. The piston rod of the hydraulic cylinder 117 contracts and pulls the bulging mold core 107 downward, and the surrounding eight-petal bulging mold petals 106 are synchronously radially expanded under the radial component force P2 of the oblique extrusion force P of the bulging mold core 107, and the inner wall of the steel plate cylindrical part is bulged and precisely shaped.

[0061] In this embodiment, a pair of mounting holes 109a are symmetrically provided at the lower part of the mounting block 109, and a compression spring 111 is slidably connected in the mounting hole 109a, and the inner end of the compression spring 111 abuts against the side of the sliding plate 105, and the mounting block 109 is connected to a blocking sheet 112 at the outer end of the pair of mounting holes 109a. The piston rod of the hydraulic cylinder 117 is extended and pushes the expansion mold core 107 to move upward, and the surrounding eight-petal expansion mold 106 is synchronously radially contracted under the radial force generated by the corresponding compression spring 111, so as to facilitate the loading and unloading of the steel plate cylindrical part.

[0062] In this embodiment, the upper surface of the mounting plate 104 is evenly distributed with oil grooves 104a, the upper surface of the sliding plate 105 is evenly distributed with oil grooves 105a, and the upper surface of the mounting block 109 is provided with oil holes 109b connected with the oil grooves 105a. When the lubricating oil flows into the oil grooves 104a, the friction and wear between the sliding plate 105 and the wear-resistant mounting plate 104 can be reduced. The lubricating oil flows into the oil grooves 105a through the oil holes 109b to reduce the friction and wear between the sliding plate 105 and the wear-resistant mounting sheet 110.

[0063] In this embodiment, the oblique conical surface of the bulging mold core 107 is evenly distributed with oil grooves 107a, and a circular oil storage groove 107b is centrally provided on the upper end surface of the bulging mold core 107, and a dust cover 108 is detachably connected to the upper side of the oil storage groove 107b. A certain amount of lubricating oil can be temporarily stored in the oil storage groove 107b, and the lubricating oil in the oil storage groove 107b can flow into the oil groove 107a through the oil hole 107c to reduce the friction and wear between the bulging mold core 107 and the bulging mold 106.

[0064] In this embodiment, the piston rod of the hydraulic cylinder 117 is sleeved with a limiting sleeve 121 between the connecting plate 119 and its cylinder barrel. The limiting sleeve 121 can limit the contraction length of the hydraulic cylinder 117, thereby limiting the downward stroke of the tire expansion mold core 107.

[0065] In this embodiment, the number of the bulging mold halves 106 is eight, and the outer wall surface of the bulging mold core 107 is an oblique cone surface divided into eight equal parts. From the perspective of shaping, the more bulging mold halves 106 the better, but considering that the manufacturing cost will increase accordingly, eight bulging mold halves 106 are selected, which is conducive to the gaps between the fan-shaped bulging mold halves 106 being distributed as evenly as possible on the circumference.

[0066] In this embodiment, two rows of staggered teeth 1061 are symmetrically arranged on both sides of the bulging mold 106, and a staggered opening 106a is formed between two adjacent staggered teeth 1061, and the staggered teeth 1061 on the bulging mold 106 are correspondingly inserted into the staggered opening 106a of the adjacent bulging mold 106. When the multiple bulging molds 106 with staggered teeth 1061 expand the inner wall of the steel plate cylindrical part at the same time, the inner wall surface of the steel plate cylindrical part is evenly expanded due to its specially designed bulging structure, and there is no obvious parting surface caused by the gap generated by the expansion of the bulging, which affects the dimensional accuracy of the inner circle and inner diameter, eliminating the influence of the multiple bulging molds 106 without staggered teeth 1061 on the shaping accuracy of the inner wall of the steel plate cylindrical part when the inner wall of the steel plate cylindrical part is expanded at the same time.

[0067] The working principle of this steel plate cylindrical inner wall precision shaping equipment:

[0068] The piston rod of the hydraulic cylinder 117 contracts and pulls the expansion mold core 107 downward, and the surrounding eight-petal expansion mold 106 simultaneously expands radially under the action of the radial component force P2 of the oblique extrusion force P of the expansion mold core 107, and expands and precisely shapes the inner wall of the steel plate cylindrical part.

[0069] The piston rod of the hydraulic cylinder 117 is extended and pushes the expansion mold core 107 to move upward, and the surrounding eight-petal expansion mold 106 is radially contracted synchronously under the radial force generated by the corresponding compression springs 111, so as to facilitate the loading and unloading of the steel plate cylindrical parts.

[0070] For steel plate cylindrical parts made of plates from different steel mills and metal plates of different materials, in order to achieve the required dimensional accuracy during the shaping process, fine adjustments are made by rotating the locking nut 116 connected to the tire expansion mold core 107 and / or rotating the locking nut 2 118 connected to the piston rod of the hydraulic cylinder 117 to adapt to the differences in steel plates of different materials and from different steel mills.

[0071] Based on our company's test data over the years, the diameters of steel plate cylindrical parts and the differences in material properties have led to the calculation formula for the corresponding radial expansion amount of plastic deformation, as described above.

[0072] It is worth noting that if other parts (such as junction boxes and heat sinks) are welded to the outer wall of steel plate cylinders, the internal stress of welding will cause changes in the dimensional accuracy of the inner wall. In order to effectively eliminate the internal stress of steel plate cylinders, several workpieces are fixed on the vibration aging platform with pneumatic clamps for vibration aging treatment. After the vibration aging treatment, the workpieces are placed on another shaping equipment for elastic deformation and shaping treatment to further eliminate the internal stress of the workpiece and ensure the accuracy of the inner wall size of the steel plate cylinder.

[0073] After the steel plate cylindrical parts undergo radial expansion and bulging, and the cylinder is welded with other parts, there are internal stress and welding internal stress caused by the dislocation deformation of the organizational grains and the change of substructure in the cylinder pipe. Through vibration aging treatment, when the vector of the residual stress and additional vibration stress inside the workpiece exceeds the yield strength of the material, the workpiece material undergoes a slight plastic deformation, thereby relaxing and reducing the internal stress inside the material, and finally achieving the requirements of stable workpiece size and geometric accuracy.

[0074] Therefore, the embodiments disclosed above are only illustrative in all aspects and are not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are included in the present invention.

Claims

1. A processing method for improving the shape and position tolerance accuracy of the inner wall of a steel plate cylindrical part hole, characterized in that: The processing steps include: S1: A bulging machine with staggered teeth (1061) on a bulging die (106) is used to perform radial plastic deformation expansion and shaping on a steel plate cylinder, wherein the plastic deformation radial expansion amount is calculated by the formula: ▽d=1.2d δt / AND; in: d: inner diameter of cylinder (mm); ▽d: plastic deformation expansion (mm); Δt: Internal stress of cylinder when internal pressure is applied (kg / cm 2 ); E: elastic modulus (kg / cm 2 ); S2: After the relevant parts are welded on the outer wall of the steel plate cylinder, the steel plate cylinder is fixed on the vibration aging platform with a pneumatic clamp to perform vibration aging treatment to remove the internal stress of the steel plate cylinder; S3: radially elastically deforming and expanding the steel plate cylinder by using a bulging machine without staggered teeth (1061) on the bulging mold halves (106); S4: Shot peening is performed on the surface of the steel plate cylinder to remove surface dirt and oxide layer.

2. A processing method for improving the shape and position tolerance accuracy of the inner wall of a steel plate cylindrical part hole, characterized in that: The bulging machine comprises a tire mold template (101), a support frame (102), a tire expansion mold flap (106), a tire expansion mold core (107), a lifting plate (115) and a hydraulic cylinder (117); the tire mold template (101) is horizontally installed on the upper side of the support frame (102), and a plurality of supporting legs (103) are evenly connected to the lower side of the support frame (102); a circular mounting groove (101a) is centrally provided on the upper surface of the tire mold template (101), and a circular through hole (101b) is centrally provided at the bottom of the mounting groove (101a); a circular mounting plate (104) is coaxially connected in the mounting groove (101a), and a plurality of sliding plates (105) in a circular array are slidably connected to the upper side of the mounting plate (104); the tire expansion mold flap (106) is provided with a plurality of and are correspondingly connected to the upper side of each sliding plate (105); the inner wall surface of the bulging mold flap (106) is a beveled surface; the bulging mold core (107) is coaxially inserted at the through hole (101b); the outer wall surface of the bulging mold core (107) is an inclined conical surface, and the inclined conical surface of the bulging mold core (107) is in sliding contact with the beveled surface of the bulging mold flap (106); the tire mold template (101) is connected to an inverted L-shaped mounting block (109) on the outer side of each sliding plate (105); the inner side of the mounting block (109) is horizontally connected to a mounting plate (110), and the lower surface of the mounting plate (110) is in sliding contact with the upper surface of the sliding plate (105); the hydraulic cylinder (117) is arranged below the tire mold template (101) and drives the bulging mold core (107) to rise and fall.

3. A processing method for improving the shape and position tolerance accuracy of the inner wall of a steel plate cylindrical part hole according to claim 2, characterized in that: Two pairs of guide pillars (113) are symmetrically connected to the lower side of the tire mold template (101), and each guide pillar (113) is slidably connected to a guide sleeve (114). The lifting plate (115) is horizontally connected between all the guide sleeves (114). The lower end of the tire expansion mold core (107) is fixed to the center of the lifting plate (115) through a pair of locking nuts (116). The hydraulic cylinder (117) is vertically installed on the lower ends of all the guide pillars (113), and a connecting plate (119) is coaxially connected to the end of its piston rod through a pair of locking nuts (118). A plurality of connecting rods (120) in a circular array are connected between the connecting plate (119) and the lifting plate (115).

4. A processing method for improving the shape and position tolerance accuracy of the inner wall size of a steel plate cylindrical part hole according to claim 2, characterized in that: A pair of mounting holes (109a) are symmetrically provided at the lower part of the mounting block (109), and a compression spring (111) is slidably connected in the mounting holes (109a), and the inner end of the compression spring (111) abuts against the side of the sliding plate (105), and the mounting block (109) is connected to a blocking sheet (112) at the outer end of the pair of mounting holes (109a).

5. A processing method for improving the geometric tolerance accuracy of the inner wall of a steel plate cylindrical part hole according to claim 2, characterized in that: The upper surface of the mounting plate (104) is evenly distributed with oil grooves 1 (104a), the upper surface of the sliding plate (105) is distributed with oil grooves 2 (105a), and the upper surface of the mounting block (109) is provided with oil holes 2 (109b) communicating with the oil grooves 2 (105a).

6. A processing method for improving the shape and position tolerance accuracy of the inner wall of a hole of a steel plate cylindrical part according to claim 2, characterized in that: The oblique conical surface of the tire expansion mold core (107) is evenly distributed with oil grooves (107a), and a circular oil storage groove (107b) is centrally provided on the upper end surface of the tire expansion mold core (107), and a dust cover (108) is detachably connected to the upper side of the oil storage groove (107b).

7. A processing method for improving the geometric tolerance accuracy of the inner wall of a steel plate cylindrical part hole according to claim 2, characterized in that: The piston rod of the hydraulic oil cylinder (117) is sleeved with a limiting sleeve (121) between the connecting plate (119) and its cylinder barrel.

8. A processing method for improving the geometric tolerance accuracy of the inner wall of a steel plate cylindrical part hole according to claim 2, characterized in that: The number of the bulging mold halves (106) is eight, and the outer wall surface of the bulging mold core (107) is an oblique cone surface divided into eight equal parts.

9. A processing method for improving the geometric tolerance accuracy of the inner wall of a hole of a steel plate cylindrical part according to any one of claims 2 to 8, characterized in that: Two rows of staggered teeth (1061) are symmetrically arranged on both sides of the tire expanding mold halves (106), and a staggered opening (106a) is formed between two adjacent staggered teeth (1061), and the staggered teeth (1061) on the tire expanding mold halves (106) are correspondingly inserted into the staggered openings (106a) of adjacent tire expanding mold halves (106).

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