Forming apparatus and method for a hollow axle half

Abstract

The application discloses a kind of forming equipment and method of hollow half shaft, belong to automobile parts manufacturing field, it includes hierarchical reducing device, the hierarchical reducing device is used to carry out successive reducing on hollow half shaft blank;Cold extrusion spline device, the cold extrusion spline device is used to extrude inner spline on hollow half shaft blank;The hierarchical reducing device includes: first reducing die, the first reducing die is used to extrude the outline of hollow half shaft on hollow half shaft blank;Second reducing die, the second reducing die is used to reduce the hollow half shaft blank of the first reducing die output to target diameter;First reducing die, second reducing die and cold extrusion spline device are cooperated in the application, utilize cold-rolled steel tube as hollow half shaft blank multiple reducing forming hollow half shaft, can reduce material consumption, can avoid the adverse phenomena such as eccentricity of center hole, uneven wall thickness when machining special-shaped deep hole on material rod simultaneously.

Description

Technical Field

[0001] This invention relates to the field of automotive parts manufacturing, and more specifically, to a forming device and method for hollow half-shafts. Background Technology

[0002] The half-shaft of a car, also known as the drive shaft, is the shaft that connects the differential to the drive wheels. As a part that transmits torque in a car, the half-shaft has mandatory requirements for its torsional strength. In the industry, half-shafts are generally made by solid shaft forging, which results in relatively high weight. However, with the current national advocacy for energy conservation and emission reduction, reducing vehicle weight is a development trend, and solid half-shafts can no longer meet the needs of industry development. Therefore, the hollowing process of half-shafts has naturally become a cutting-edge technology discussed in the industry.

[0003] The machining steps for hollow half-shafts in related technologies include: lead bar stock -> rough turning -> deep hole machining -> semi-finish turning -> finish turning. Since hollow half-shafts are mostly special-shaped tubes with varying inner diameters, in order to meet the usage requirements, it is often necessary to machine and drill irregular deep holes with varying diameters inside the stock obtained after rough turning. When using existing methods to process hollow half-shafts from solid stock, the large volume of the stock blank results in a large amount of material consumption, low material utilization, and expensive deep hole machining equipment. Machining irregular deep holes on the stock is difficult, which not only easily leads to defects such as center hole eccentricity and uneven wall thickness, but also presents technical problems such as difficulty in calibrating the inner hole, ultimately affecting the strength of the half-shaft. Summary of the Invention

[0004] The purpose of this invention is to solve the technical problems of high material consumption and poor center hole forming quality when processing hollow half shafts in the prior art, and to propose a hollow half shaft forming equipment and method.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] The first aspect of this invention provides a hollow half-shaft forming device, comprising:

[0007] A graded diameter reduction device is used to gradually reduce the diameter of a hollow half-shaft blank.

[0008] A cold extrusion spline device, used for extruding internal splines on a hollow half-shaft blank;

[0009] The graded diameter reduction device includes:

[0010] The first diameter reduction die is used to extrude the shape of the hollow half shaft onto the hollow half shaft blank.

[0011] The second diameter reduction die is used to reduce the diameter of the hollow half-shaft blank output by the first diameter reduction die to the target diameter.

[0012] Furthermore, the first diameter reduction die includes: a first upper die, a first lower die located directly below the first upper die, and a mandrel; wherein, the first upper die is used to press the hollow half-shaft blank into the first lower die for initial diameter reduction, including:

[0013] The first upper pad is connected to an external pressurizing device;

[0014] The first upper pressure head cover is detachably connected to the lower part of the first upper pad block, and the first upper pressure head cover has an accommodating space inside;

[0015] The upper positioning pad is connected to the inside of the first upper pressure head outer sleeve, and the upper positioning pad and the first upper pressure head outer sleeve cooperate to form a mandrel groove;

[0016] The first lower mold includes:

[0017] The first diameter reduction die body has a diameter reduction through hole provided on it, and the diameter of the diameter reduction through hole on the first diameter reduction die body gradually decreases from one end face of the first diameter reduction die body to the other end face.

[0018] The first guide cover has a cylindrical structure and is connected above the first diameter reduction die body. It is used to guide the hollow half-shaft blank and restrict the outward expansion of the hollow half-shaft blank.

[0019] The first upper pressure ring is connected above the first guide cover and is used to limit the outward expansion of the first guide cover;

[0020] The first lower die pull ring, the first diameter reduction die body, and the first guide cover are disposed inside the first lower die pull ring; the first lower die pull ring is attached to and pressed against the first upper pressure ring above the first upper pressure ring;

[0021] The first lower mold cavity is connected directly below the first lower mold pull ring, and an accommodating space is provided inside the first lower mold cavity;

[0022] The first guide sleeve is disposed inside the first lower mold cavity and located below the first diameter reduction mold body. The position of the first guide sleeve corresponds to the diameter reduction through hole on the first diameter reduction mold body, and is used to correct and straighten the hollow half shaft blank output by the first diameter reduction mold body.

[0023] The first lower die guide sleeve is sleeved on the outside of the first straight guide sleeve to limit the deformation of the first straight guide sleeve;

[0024] The first lower pad assembly is disposed inside the first lower mold cavity and is used to fix the first guide sleeve and the first lower mold guide sleeve inside the first lower mold cavity;

[0025] The first pressing ring is sleeved on the outside of the first lower mold cavity and the first lower mold pull ring, and presses the first lower mold pull ring tightly above the first lower mold cavity;

[0026] The mandrel limiting clamp is engaged in the mandrel slot, so that the hollow half-shaft blank is positioned at the lower end of the first upper pressure head outer sleeve, and a support is formed inside the hollow half-shaft blank.

[0027] Furthermore, the mandrel includes:

[0028] The positioning end is matched in shape and size to the mandrel slot.

[0029] The support end is a multi-segment columnar structure, the diameter of which gradually decreases from one end near the positioning end to the other end.

[0030] A positioning ring is provided at the connection between the positioning end and the support end, and the positioning ring is used to mark the axial position of the mandrel in the hollow half-shaft blank.

[0031] Furthermore, the second diameter reduction die includes: a second upper die and a second lower die located directly below the second upper die; wherein, the second upper die is used to press the hollow half-shaft blank output from the first diameter reduction die into the second lower die for a second diameter reduction, including:

[0032] The second upper pad is connected to the external pressurization device;

[0033] The second upper pressure head cover is detachably connected to the lower part of the second upper pad block, and a fixing space is provided at the lower end of the second upper pressure head cover;

[0034] The upper pressure head has its upper end detachably connected to the fixed space of the second upper pressure head sleeve, and its lower end located below the second upper pressure head sleeve. The lower surface of the upper pressure head is provided with a groove that is adapted to the hollow half-shaft blank.

[0035] The second lower mold includes:

[0036] The second diameter reduction die body has a diameter reduction through hole provided on it; the diameter of the diameter reduction through hole on the second diameter reduction die body gradually decreases from one end face of the second diameter reduction die body to the other end face.

[0037] The second guide cover has a through hole for the hollow half-shaft blank to pass through. The second guide cover is connected to the upper part of the second diameter reduction die body. A straightening component is provided above the second guide cover to keep the hollow half-shaft blank in the second guide cover vertical.

[0038] The second upper pressure ring is connected above the second guide cover and is used to limit the outward expansion of the second guide cover;

[0039] The second lower die pull ring, the second diameter reduction die body, and the second guide cover are disposed inside the second lower die pull ring; the second lower die pull ring is attached to and pressed against the second upper pressure ring above the second upper pressure ring;

[0040] The second lower mold cavity is connected directly below the second lower mold pull ring, and an accommodating space is provided inside the second lower mold cavity;

[0041] The second guide sleeve is disposed inside the second lower mold cavity and located below the second diameter reduction mold body. The position of the second guide sleeve corresponds to the diameter reduction through hole on the second diameter reduction mold body, and is used to correct and straighten the hollow half shaft blank output by the second diameter reduction mold body.

[0042] The second lower die guide sleeve is sleeved on the outside of the second guide sleeve and is used to limit the deformation of the second guide sleeve;

[0043] The second lower pad assembly is disposed inside the second lower mold cavity and is used to fix the second guide sleeve and the second lower mold guide sleeve inside the second lower mold cavity;

[0044] The second lower pressure ring is sleeved on the outside of the second lower mold cavity and the second lower mold pull ring, so that the second lower mold pull ring and the second lower mold cavity are connected to form a whole.

[0045] Furthermore, the cold extrusion spline device includes: a third upper die and a third lower die located directly below the third upper die; wherein the third upper die includes:

[0046] The third upper pad is connected to an external pressurizing device;

[0047] The third upper pressure head cover is detachably connected to the lower part of the third upper pad block, and a fixing space is provided on the third upper pressure head cover;

[0048] The upper pressure head spindle is vertically connected to the fixed space of the third upper pressure head sleeve, and a screw hole is provided at the lower end of the upper pressure head spindle;

[0049] The tooth mold has a ring structure and is disposed at the lower end of the upper pressure head mandrel, and moves synchronously with the upper pressure head mandrel;

[0050] A locking bolt passes through the toothed mold and is threaded into the threaded hole of the upper pressure head spindle, thereby limiting and locking the toothed mold to the lower end of the upper pressure head spindle;

[0051] The third lower mold includes:

[0052] The third lower mold cavity is cylindrical in shape and has an internal accommodating space.

[0053] A die is provided in the third lower die cavity. The die has a through hole that matches the diameter of the hollow half-shaft blank, which is used to guide the hollow half-shaft blank into the die. The die is located directly below the upper pressure head mandrel, and the axis of the through hole on the die is on the same axis as the upper pressure head mandrel.

[0054] A die sleeve is fitted over the outside of the die and abuts against the inner wall of the third lower die cavity to fix the die and prevent it from cracking.

[0055] A push rod is disposed at the lower end of the third lower mold cavity and located directly below the die cavity, for providing support below the hollow half-shaft blank;

[0056] The third lower pad assembly is disposed inside the third lower mold cavity and abuts against the lower surface of the die cavity and the die cavity outer sleeve. The third lower pad assembly is used to fill the gap between the hollow half-shaft blank, the ejector rod and the third lower mold cavity, and to fix the hollow half-shaft blank and the ejector rod in the third lower mold cavity.

[0057] The third pressure ring is sleeved on the outside of the third lower mold cavity to limit the outward expansion of the third lower mold cavity.

[0058] Furthermore, an adjustment slot is provided horizontally between the third upper pressure head sleeve and the third upper pad block. A first self-aligning screw hole is provided through the side of the third upper pad block, and a second self-aligning screw hole corresponding to the position of the first self-aligning screw hole is provided on the side of the third upper pressure head sleeve. A self-aligning bolt is internally threaded into the first self-aligning screw hole and the second self-aligning screw hole. The self-aligning bolt is used to adjust the relative position of the third upper pressure head sleeve and the third upper pad block.

[0059] Furthermore, the first diameter reduction die body adopts a double-layer structure of inner and outer molds, including:

[0060] The inner mold has a reduced diameter through hole on the first reduced diameter mold body located at the center of the end face of the inner mold.

[0061] An outer mold is fitted over the outer side of the inner mold. The outer mold and the inner mold are joined by heat sealing. The outer mold is used to provide inward prestress to the inner mold.

[0062] Furthermore, the large end diameter of the through hole on the first diameter reduction die body matches the diameter of the hollow half-shaft blank, and the small end diameter of the through hole on the first diameter reduction die body is 70% to 85% of its large end diameter.

[0063] A second aspect of the present invention provides a method for forming a hollow half-shaft, using the hollow half-shaft forming equipment described in the first aspect, comprising the following steps:

[0064] S1: Cold-rolled steel pipes with a blanking diameter of Φ50×Φ30 are used as blanks for hollow half shafts;

[0065] S2: Place the pre-cut hollow half-shaft blank into a continuous furnace for normalizing treatment;

[0066] S3: Shot blasting of hollow half-shaft blank surface, shot blasting frequency 30Hz, shot blasting time 30min;

[0067] S4: After the hollow half-shaft blank is fully preheated, it is hoisted into the first lubricant tank and soaked for 5 to 10 seconds; then the hollow half-shaft blank is hoisted up and air-dried for 10 minutes, and then naturally air-dried for 24 hours to ensure that the surface of the hollow half-shaft blank is covered with a lubricating film layer with a thickness of 20 to 80 μm.

[0068] S5: Place the hollow half-shaft blank into the first diameter reduction mold for the first diameter reduction;

[0069] S6: Place the hollow half-shaft blank after the first diameter reduction into the second diameter reduction mold for the second diameter reduction;

[0070] S7: Stress-relief tempering of hollow half-shaft blanks;

[0071] S8: Finish machine the part of the hollow half-shaft blank to be extruded internal spline to the preset required size;

[0072] S9: After the hollow half-shaft blank is fully preheated, it is hoisted into the second lubricant tank and soaked for 5 to 10 seconds; then the hollow half-shaft blank is hoisted up and air-dried for 10 minutes, and then naturally air-dried for 24 hours to ensure that the surface of the hollow half-shaft blank is covered with a lubricating film layer with a thickness of 20 to 80 μm.

[0073] S10: Place the hollow half-shaft blank into the cold extrusion spline device to extrude the internal spline;

[0074] S11: The hollow half-shaft blank is precision machined to the preset required size, and the hobbing position size on the hollow half-shaft blank is machined to the center line of the spline major diameter;

[0075] S12: Center hole of double-top hollow half-shaft blank, spline machined by gear hobbing;

[0076] S13: The surface of the hollow half-shaft blank is quenched by medium frequency heating. The medium frequency quenching frequency is 6KHZ to 10KHZ, the current is 82A, and the workpiece rotation speed is 30r / min.

[0077] S14: Grind the bearing position on the hollow half-shaft blank to the preset required size.

[0078] The beneficial effects of the present invention are as follows: The hollow half-shaft forming equipment provided in this application adopts a first diameter reduction mold, a second diameter reduction mold and a cold extrusion spline device in combination, and directly uses cold rolled steel pipe to form hollow half-shafts through multiple diameter reductions. This optimizes the steps of deep hole processing of material bars in related technologies, which can reduce material consumption and avoid adverse phenomena such as center hole eccentricity and uneven wall thickness when processing irregular deep holes on material bars. Attached Figure Description

[0079] Figure 1 This is a schematic diagram of the internal structure of the first diameter reduction mold in an embodiment of the present invention;

[0080] Figure 2 This is a schematic diagram of the main structure of the first diameter reduction die in an embodiment of the present invention;

[0081] Figure 3 This is a schematic diagram of the internal structure of the second diameter reduction mold in an embodiment of the present invention;

[0082] Figure 4 This is a schematic diagram of the straightening component structure in an embodiment of the present invention;

[0083] Figure 5 This is a schematic diagram of the internal structure of the cold extrusion spline device in an embodiment of the present invention.

[0084] The markings in the diagram are as follows:

[0085] 11. First diameter reduction mold; 111. First upper mold; 1111. First upper pad block; 1112. First upper pressure head sleeve; 11121. Mandrel slot; 1113. Upper positioning pad; 112. First lower mold; 1121. First diameter reduction mold body; 11211. Inner mold; 11212. Outer mold; 1122. First guide cover; 1123. First upper pressure ring; 1124. First lower mold pull ring; 1125. First lower mold cavity; 1126. First guide sleeve; 1127. First lower mold guide sleeve; 1128. First lower pad block assembly; 11281. First lower pad block; 11282. Second lower pad block; 11283. Third lower pad block; 1129. First lower pressure ring; 113. Mandrel; 1131. Positioning end; 1132. Support end;

[0086] 12. Second reducing die; 121. Second upper die; 1211. Second upper pad block; 1212. Second upper pressure head sleeve; 1213. Upper pressure head; 122. Second lower die; 1221. Second reducing die body; 1222. Second guide cover; 12221. Pressure plate; 12222. Slider; 12223. Spring clamp; 1223. Second upper pressure ring; 1224. Second lower die pull ring; 1225. Second lower die cavity; 1226. Second guide sleeve; 1227. Second lower die guide sleeve; 1228. Second lower pad block assembly; 1229. Second lower pressure ring;

[0087] 2. Cold extrusion spline device; 211. Third upper die; 2111. Third upper pad block; 2112. Third upper pressure head outer sleeve; 2113. Upper pressure head mandrel; 2114. Gear die; 2115. Locking bolt; 2116. Self-aligning bolt; 212. Third lower die; 2121. Third lower die cavity; 2122. Die cavity; 2123. Die cavity outer sleeve; 2124. Ejector rod; 2125. Third lower pad block assembly; 2126. Third lower pressure ring. Detailed Implementation

[0088] In this embodiment, the hollow half-shaft blank is made of pretreated cold-rolled steel pipe; please refer to [link / reference]. Figures 1 to 5 The embodiment of this application shown provides a hollow half-shaft forming equipment. In practical applications, the hollow half-shaft forming equipment is used to change the overall shape and inner diameter of the cold-rolled steel pipe, so that the cold-rolled steel pipe blank is formed into a hollow half-shaft with uniform wall thickness. The weight of the half-shaft is reduced without reducing performance, thereby achieving the purpose of energy saving and emission reduction.

[0089] The hollow half-shaft forming equipment includes: a graded diameter reduction device and a cold extrusion spline device 2; the graded diameter reduction device is used to gradually reduce the diameter of the cold-rolled steel pipe, and the cold extrusion spline device 2 is used to extrude internal splines on the cold-rolled steel pipe, which mesh with the external splines of the wheel hub to transmit the torque output by the gearbox to the drive wheel.

[0090] Due to the limitation of material deformation, cold-rolled steel pipes cannot be reduced to the target diameter in one step. This application adopts a step-by-step reduction technology. The step-by-step reduction device includes a first reduction die 11 and a second reduction die 12. The first reduction die 11 is used to extrude the overall shape of the hollow half shaft on the cold-rolled steel pipe, and the second reduction die is used to reduce the diameter of the cold-rolled steel pipe output from the first reduction die 11 to the target diameter.

[0091] For more details, please see Figure 1 The first diameter reduction mold 11 includes: a first upper mold 111, a first lower mold 112, and a mandrel 113; wherein, the first upper mold 111 includes: a first upper pad 1111, a first upper pressure head sleeve 1112, and an upper positioning pad 1113; the first upper pad 1111 is connected to an external pressurizing device and is used to transmit the pressure applied by the external pressurizing device. In this embodiment, the external pressurizing device is a press; the first upper pressure head sleeve 1112 is the main load-bearing component in the first upper mold 111, and the first upper pressure head sleeve 1112 is detachably connected to the lower part of the first upper pad 1111. The first upper pressure head sleeve 1112 has a space inside for accommodating the upper positioning pad 1113 and the mandrel 113. The upper positioning pad 1113 is connected to the inside of the first upper pressure head sleeve 1112 and forms a mandrel groove 11121 at the lower end of the first upper pressure head sleeve 1112 that is adapted to the shape and size of the end of the mandrel 113. The upper positioning pad 1113 is used to limit the relative position between the mandrel 113 and the first upper pressure head sleeve 1112. The first upper pressure head sleeve 1112 and the upper positioning pad 1113 cooperate to realize the limiting and fixing of the mandrel 113 on the first upper mold 111.

[0092] In this embodiment, the first upper pad 1111 is made of Cr12MoV material with a heat treatment hardness of 58 to 62 HRC; the first upper pressure head outer sleeve 1112 is made of Cr12MoV material with a heat treatment hardness of 58 to 62 HRC; and the upper positioning pad 1113 is made of 40Cr material with a modulated hardness of 28 to 32 HRC.

[0093] The first lower die 112 is located directly below the first upper die 111, and includes: a first diameter-reducing die body 1121, a first guide cover 1122, a first upper pressure ring 1123, a first lower die pull ring 1124, a first lower die cavity 1125, a first guide sleeve 1126, a first lower die guide sleeve 1127, a first lower pad assembly 1128, and a first lower pressure ring 1129; the first diameter-reducing die body 1121 is generally annular in structure, with a diameter-reducing through hole in its middle, and the diameter of the diameter-reducing through hole extends from one end of the first diameter-reducing die body 1121 to the other end. The diameter of the large end of the through hole on the first diameter reduction die body 1121 is matched with that of the cold-rolled steel pipe, and the diameter of the small end is 70% to 85% of the diameter of the large end. The side end face where the large end of the through hole on the first diameter reduction die body 1121 is located is set upward and close to the first upper die 111. The first diameter reduction die body 1121 is the main component for realizing the first diameter reduction effect of the cold-rolled steel pipe. The outer diameter of the diameter reduction part of the cold-rolled steel pipe gradually decreases as it passes through the diameter reduction through hole until the diameter reduction part completely passes through the small end of the diameter reduction through hole, and the first diameter reduction is completed.

[0094] The first guide cover 1122 has a cylindrical structure with a through hole in its middle that allows the cold-rolled steel pipe to pass through. The diameter of the through hole on the first guide cover 1122 matches the large end diameter of the diameter reduction through hole. Annular grooves are provided on the edges of both sides of the first guide cover 1122. The first diameter reduction die body 1121 is snapped and fixed inside the annular groove on the lower end face of the first guide cover 1122, ensuring that the axis of the diameter reduction through hole and the through hole on the first guide cover 1122 are aligned. The first guide cover 1122 plays a guiding role during the diameter reduction movement of the cold-rolled steel pipe and simultaneously restricts the outward expansion of the cold-rolled steel pipe.

[0095] The shape and size of the first upper pressure ring 1123 are matched with the annular groove on the upper end face of the first guide cover 1122, and it is locked and fixed to the outside of the annular groove on the upper end face of the first guide cover 1122, further restricting the first guide cover 1122 from expanding outward due to the compression of the cold-rolled steel pipe.

[0096] The inner diameter of the first lower die pull ring 1124 matches the outer diameter of the first upper pressure ring 1123. The inner wall at the upper end and the outer wall at the lower end of the first lower die pull ring 1124 are respectively provided with protruding structures. The first diameter reduction die body 1121, the first guide cover 1122, and the first upper pressure ring 1123 are connected to the inside of the first lower die pull ring 1124, and the first upper pressure ring 1123 is in contact with the inner wall of the first lower die pull ring 1124. The first lower die pull ring 1124 is pressed against the first upper pressure ring 1123 through the protruding structure on its inner wall.

[0097] The first lower mold cavity 1125 is generally tubular in shape. Its interior is a space for accommodating the first guide sleeve 1126, the first lower mold guide sleeve 1127, and the first lower pad assembly 1128. One end of the first lower mold cavity 1125 is detachably connected to the worktable of the press, and the other end is connected directly below the first lower mold pull ring 1124, which serves to limit the movement of the components in the internal space of the first lower mold cavity 1125.

[0098] The first guide sleeve 1126 is a tubular structure, and its inner diameter matches the small end diameter of the diameter reduction through hole on the first diameter reduction die body 1121. The first guide sleeve 1126 is set inside the first lower die cavity 1125 and is located below the first diameter reduction die body 1121. The position of the first guide sleeve 1126 and the diameter reduction through hole on the first diameter reduction die body 1121 are corresponding, so that the axis of the first guide sleeve 1126 and the axis of the diameter reduction through hole are on the same straight line. After the diameter reduction part on the cold-rolled steel pipe is completed, it leaves the first diameter reduction die body 1121 and is further inserted into the first guide sleeve 1126, continuing to move along the inner wall of the first guide sleeve 1126. The first guide sleeve 1126 plays a corrective and guiding role, avoiding excessive bending of the pipe wall after the diameter reduction of the cold-rolled steel pipe.

[0099] The first lower die guide sleeve 1127 is fitted onto the outside of the first guide sleeve 1126 to limit the deformation of the first guide sleeve 1126. The first lower pad assembly 1128 is disposed inside the first lower die cavity 1125, and it plays a supporting role between the first guide sleeve 1126, the press working platform, and the first lower die cavity 1125, so that the positions of the first guide sleeve 1126 and the first lower die guide sleeve 1127 are fixed in the first lower die cavity 1125. By filling the gap in the first lower die cavity 1125 with the first lower pad assembly 1128, the overall stability of the first lower die 112 is improved, and its impact resistance and fatigue resistance are stronger, which can avoid damage to the first guide sleeve 1126 caused by stress imbalance.

[0100] The inner diameter of the first lower pressure ring 1129 matches the outer diameter of the first lower mold cavity 1125. The inner wall of the first lower pressure ring 1129 is provided with a protruding structure that cooperates with the first lower mold pull ring 1124. The first lower pressure ring 1129 is sleeved on the outside of the first lower mold cavity 1125 and the first lower mold pull ring 1124, and the protruding structure on the inner wall of the first lower pressure ring 1129 abuts against the protruding structure on the outer wall of the first lower mold pull ring 1124, thereby pressing the first lower mold pull ring 1124 above the first lower mold cavity 1125, so that the first lower mold pull ring 1124 and the first lower mold cavity 1125 are connected to form a whole.

[0101] In the above technical solution, the first lower pad assembly 1128 is made of 40Cr material with a hardness of 28 to 32 HRC, and includes: a first lower pad 11281, a second lower pad 11282, and a third lower pad 11283; the first lower pad 11281, the second lower pad 11282, and the third lower pad 11283 are all cylindrical structures, and their outer diameters match the inner diameter of the first lower mold cavity 1125; wherein, the first lower pad 11281 is located at the bottom of the first lower mold cavity 1125, used to adjust the height of the first guide sleeve 1126 and bear the pressure transmitted by the upper component; the second lower pad 11282 is placed above the first lower pad 11281 and below the first lower mold guide sleeve 1127, and the second lower pad 11282 is positioned above the first lower pad 11281. A limiting groove for engaging the first guide sleeve 1126 is provided at the center of the end face. The first guide sleeve 1126 is fixed between the second lower pad 11282 and the first diameter reduction mold body 1121. The second lower pad 11282 restricts the position of the first guide sleeve 1126 in the first lower mold cavity 1125. The middle part of the third lower pad 11283 is provided with a through hole that matches the outer diameter of the first guide sleeve 1126. The third lower pad 11283 is sleeved on the outside of the first guide sleeve 1126. The upper end of the third lower pad 11283 abuts against the lower surface of the first diameter reduction mold body 1121, and its lower end abuts against the upper surface of the first lower mold guide sleeve 1127. It cooperates with the second lower pad 11282 to press and fix the first lower mold guide sleeve 1127.

[0102] For a preferred embodiment of this application, please refer to Figure 2 The first diameter reduction die body 1121 adopts a double-layer structure of inner and outer dies, including: inner die 11211 and outer die 11212; the inner die 11211 is made of hard alloy material, and the diameter reduction through hole is opened at the center of the end face of the inner die 11211. The inner surface of the diameter reduction through hole is polished and the roughness Ra is within 0.2; the outer die 11212 is sleeved on the outside of the inner die 11211, and is made of 40Cr material with a hardness of 28 to 32 HRC. The outer die 11212 and the inner die 11211 are joined by heat sealing, and the contour junction is smoothly transitioned; the outer die 11212 provides inward prestress to the inner die 11211 to ensure that the inner die 11211 can apply sufficient clamping force to the cold-rolled steel pipe and avoid the inner die 11211 being cracked by the cold-rolled steel pipe during the diameter reduction process.

[0103] The mandrel 113 is made of 40Cr material with a tempered hardness of 28 to 32 HRC. A DLC coating is applied to the surface of the mandrel 113 to improve hardness and reduce the coefficient of friction. More specifically, the mandrel 113 includes a positioning end 1131 and a support end 1132. The length and diameter of the positioning end 1131 match the mandrel slot 11121 on the first upper pressure head sleeve 1112. The positioning end 1131 is connected to the mandrel slot 11121, thus limiting and engaging the mandrel 113 at the lower end of the first upper pressure head sleeve 1112. The support end 1132 has a multi-segment columnar structure, and its diameter gradually decreases from one end near the positioning end 1131 to the other end. In this embodiment, the support end 1132 of the mandrel 113 is configured as two segments, wherein the segment near the positioning end 1131... The diameter of the section matches the diameter of the cold-rolled steel pipe. The diameter of the section away from the positioning end 1131 is the target inner diameter of the cold-rolled steel pipe after the first reduction in diameter. The two sections of the support end 1132 have a smooth transition. The support end 1132 is used to provide support inside the cold-rolled steel pipe, so that the supported area of ​​the cold-rolled steel pipe is squeezed and extended during the first reduction in diameter. The inner diameter of the cold-rolled steel pipe is reduced to the target size, while the wall thickness of the squeezed and extended part of the cold-rolled steel pipe remains uniform. A positioning ring is set at the connection between the positioning end 1131 and the support end 1132 of the mandrel 113. The positioning ring is used to mark the axial position of the mandrel 113 in the cold-rolled steel pipe. When the mandrel 113 is inserted into the cold-rolled steel pipe until the positioning ring is flush with the pipe opening, it indicates that the mandrel 113 is in the correct position inside the cold-rolled steel pipe, and the positioning between the mandrel 113 and the cold-rolled steel pipe is completed.

[0104] In one embodiment of this application, the hollow half-shaft blank is a cold-rolled steel pipe with a diameter of Φ50×Φ30mm and a length of 330mm, made of 40Cr. The positioning end 1131 of the mandrel 113 has a diameter of 30mm, and the support end 1132 has a diameter of 24mm. The large end diameter of the diameter reduction through hole on the main body 1121 of the first diameter reduction die is 50mm, and the small end diameter is 41.5mm. When the cold-rolled steel pipe is reduced in diameter for the first time, the mandrel 113 is first inserted and positioned from the upper end of the cold-rolled steel pipe, and the lower end of the cold-rolled steel pipe is inserted into the first guide cover 1122. The cold-rolled steel pipe is straightened by the first guide cover 1122. At this time, the external pressure equipment is started, and the first upper die 111 is brought close to the mandrel 113, and the positioning end 1131 of the mandrel 113 is limited and fixed to the mandrel. Inside the shaft groove 11121, the cold-rolled steel pipe abuts against the lower surface of the outer sleeve 1112 of the first upper pressure head; the external pressure equipment continues to apply pressure, pressing the reduced diameter part of the cold-rolled steel pipe into the first reduced diameter die body 1121, passing through the first reduced diameter die body 1121 and entering the reduced diameter part of the first guide sleeve 1126 to complete the first reduced diameter, and the external pressure equipment presses down until the cold-rolled steel pipe is completely pressed into the first lower die 112; the outer diameter of the reduced diameter part of the cold-rolled steel pipe after the first reduced diameter is 41.5mm, the inner diameter is 24mm, and the wall thickness is 8.75mm; the design purpose of the first reduced diameter die 11 is to perform preliminary reduced diameter at a designated part on the cold-rolled steel pipe, so that the cold-rolled steel pipe can form the shape of a hollow half shaft, so that the subsequent second reduced diameter die 12 can reduce the diameter of the cold-rolled steel pipe to the target size on this basis.

[0105] To further reduce the diameter of the cold-rolled steel tube output from the first diameter reduction die 11 to the required size, please refer to... Figure 3 The second diameter reduction mold 12 includes a second upper mold 121 and a second lower mold 122; wherein, the second upper mold 121 includes a second upper pad 1211, a second upper pressure head sleeve 1212, and an upper pressure head 1213; the second upper pad 1211 is connected to an external pressurizing device for transmitting the pressure applied by the external pressurizing device. In this embodiment, the external pressurizing device connected to the first upper pad 1111 and the external pressurizing device connected to the second upper pad 1211 are independently provided; the second upper pressure head sleeve 1212 is detachably connected to the lower part of the second upper pad 1211, and the lower end of the second upper pressure head sleeve 1212 is provided with A space is provided for fixing the upper pressure head 1213; the upper pressure head 1213 is the main load-bearing component in the second upper die 121, and its cross-section is T-shaped. The upper pressure head 1213 is made of Cr12MoV material and has a heat treatment hardness of 58 to 62 HRC. The upper end of the upper pressure head 1213 is detachably connected to the inner side of the second upper pressure head outer sleeve 1212 by bolts, and its lower end is located below the second upper pressure head outer sleeve 1212. The lower surface of the upper pressure head 1213 is provided with a groove that matches the shape of the end of the cold-rolled steel pipe. The cold-rolled steel pipe is fixed to the upper pressure head 1213 by being clamped in the groove on the lower surface of the upper pressure head 1213.

[0106] The second lower mold 122 includes: a second diameter-reducing mold body 1221, a second guide cover 1222, a second upper pressure ring 1223, a second lower mold pull ring 1224, a second lower mold cavity 1225, a second guide sleeve 1226, a second lower mold guide sleeve 1227, a second lower pad assembly 1228, and a second lower pressure ring 1229; a diameter-reducing through hole is provided in the middle of the second diameter-reducing mold body 1221, and the diameter of the diameter-reducing through hole on the second diameter-reducing mold body 1221 gradually decreases from one end face of the second diameter-reducing mold body 1221 to the other end face, wherein the diameter-reducing through hole on the second diameter-reducing mold body 1221... The large end diameter matches the diameter of the unreduced portion of the cold-rolled steel pipe; the second reducing die body 1221 is the main component for achieving the second reducing effect of the cold-rolled steel pipe. When the reducing portion of the cold-rolled steel pipe moves within the reducing through hole of the second reducing die body 1221, the outer diameter is reduced again until the reducing portion of the cold-rolled steel pipe completely passes through the small end of the reducing through hole, and the second reducing is completed; at this time, the diameter of the cold-rolled steel pipe matches the target diameter of the hollow half shaft; based on the structure of the first reducing die body 1121, it can be understood that the second reducing die body 1221 also adopts a double-layer structure of inner and outer molds.

[0107] The second guide cover 1222 has a through hole in its center, allowing the cold-rolled steel pipe to pass through. The diameter of the through hole on the second guide cover 1222 matches the large end diameter of the through hole on the second diameter reduction die body 1221. The second guide cover 1222 is connected above the second diameter reduction die body 1221. The cold-rolled steel pipe passes through the second guide cover 1222 and enters the second diameter reduction die body 1221 for diameter reduction. Since the cold-rolled steel pipe obtained after the first diameter reduction is a shaped pipe with a changing outer diameter, when the cold-rolled steel pipe moves in the through hole on the second guide cover 1222, there is a gap between its diameter reduction portion and the second guide cover 1222. This causes the cold-rolled steel pipe to pass through the second guide cover 1222 at an angle and insert into the second diameter reduction die body 1221, ultimately affecting the quality of the second diameter reduction forming of the cold-rolled steel pipe. In the above technical solution, a straightening component is provided above the second guide cover 1222. The straightening component is used to maintain the correct axial position of the cold-rolled steel pipe in the second guide cover 1222. Please refer to [link to technical solution]. Figure 4The straightening assembly includes: a pressure plate 12221, a slider 12222, and a spring clamp 12223; the longitudinal section of the pressure plate 12221 is U-shaped, and the pressure plate 12221 is detachably connected to the upper surface of the second guide cover 1222 by bolts, forming a track between the pressure plate 12221 and the second guide cover 1222 to accommodate the slider 12222; a through hole corresponding to the position of the second guide cover 1222 is provided in the middle of the pressure plate 12221, through which a cold-rolled steel pipe can pass; the slider 12222 is located between the pressure plate 12221 and the second guide cover 1222, and is a three-lobed slider. 12222 is circumferentially arranged along the edge of the through hole of the second guide cover 1222; the spring clamp 12223 abuts against the outside of the three-lobed slider 12222, causing the three-lobed slider 12222 to move along the track and approach each other; with the design of the straightening component, during the movement of the cold-rolled steel pipe inside the second guide cover 1222, the slider 12222 can be radially scaled and moved to change the distance between the three-lobed slider 12222, thereby adapting to the diameter change of the cold-rolled steel pipe. The cold-rolled steel pipe is subjected to an inward radial clamping force and always maintains the correct axial position during the movement.

[0108] The second upper pressure ring 1223 is connected above the second guide cover 1222 and is used to limit the second guide cover 1222 from expanding outward due to the compression of the cold-rolled steel pipe.

[0109] The second diameter reduction die body 1221, the second guide cover 1222, and the second upper pressure ring 1223 are connected inside the second lower die pull ring 1224. The inner wall of the second lower die pull ring 1224 is in contact with the second upper pressure ring 1223, and the second lower die pull ring 1224 is pressed against the upper part of the second upper pressure ring 1223.

[0110] The interior of the second lower mold cavity 1225 is a space for accommodating the second guide sleeve 1226, the second lower mold guide sleeve 1227, and the second lower pad assembly 1228. The upper end of the second lower mold cavity 1225 is connected to the lower part of the second lower mold pull ring 1224. The second lower mold cavity 1225 and the second lower mold pull ring 1224 cooperate to limit the components inside the second lower mold 122.

[0111] The inner diameter of the second guide sleeve 1226 matches the small end diameter of the diameter reduction through hole on the second diameter reduction die body 1221. The second guide sleeve 1226 is located inside the second lower die cavity 1225 and below the second diameter reduction die body 1221. After the second diameter reduction is completed, the diameter reduction part on the cold-rolled steel pipe leaves the second diameter reduction die body 1221 and is inserted into the second guide sleeve 1226 for straightening.

[0112] The second lower mold guide sleeve 1227 is sleeved on the outside of the second guide sleeve 1226 to limit the deformation of the second guide sleeve 1226. The second lower pad assembly 1228 is disposed inside the second lower mold cavity 1225 to support and fix the second guide sleeve 1226 and the second lower mold guide sleeve 1227 in the second lower mold cavity 1225.

[0113] The inner diameter of the second lower pressure ring 1229 matches the outer diameter of the second lower mold cavity 1225. The second lower pressure ring 1229 is sleeved on the outside of the second lower mold cavity 1225 and the second lower mold pull ring 1224, and is located at the junction of the second lower mold cavity 1225 and the second lower mold pull ring 1224, so that the second lower mold pull ring 1224 and the second lower mold cavity 1225 are connected to form a whole, which plays a role in preventing misalignment between them.

[0114] In one embodiment of this application, the large end diameter of the reducing through hole on the second reducing die body 1221 is 50mm, and the small end diameter is 34mm. After the initial reducing of the cold-rolled steel pipe, the reduced portion of the cold-rolled steel pipe is inserted into the second guide cover 1222. The cold-rolled steel pipe is held and straightened by the straightening component, and the second upper die 121 is controlled to approach the second lower die 122. The upper end of the cold-rolled steel pipe is limited to abutting against the groove on the lower surface of the upper pressure head 1213. The second upper die 121 continues to approach the second lower die 122 to press the reduced portion of the cold-rolled steel pipe into place. The second diameter reduction die body 1221 passes through the second diameter reduction die body 1221 and enters the diameter reduction part of the second guide sleeve 1226 to complete the second diameter reduction. The second upper die 121 moves to the upper pressure head 1213 to completely press the cold-rolled steel pipe into the second lower die 122. The outer diameter of the diameter reduction part of the cold-rolled steel pipe after the second diameter reduction is 24mm. After the gradual diameter reduction, the diameter of the cold-rolled steel pipe can reach the target size. Moreover, the above scheme optimizes the deep hole processing steps in the traditional process and effectively avoids the occurrence of adverse phenomena such as center hole eccentricity and uneven wall thickness.

[0115] To continue extruding internal splines within cold-rolled steel tubes for engagement with the external splines of the wheel hub, please refer to... Figure 5In the above technical solution, the cold extrusion spline device 2 includes: a third upper die 211 and a third lower die 212; wherein, the third upper die 211 includes: a third upper pad 2111, a third upper pressure head sleeve 2112, an upper pressure head spindle 2113, a gear die 2114, and a locking bolt 2115; the third upper pad 2111 has a concave structure and is connected to an external pressurizing device to transmit the pressure applied by the external pressurizing device. In this embodiment, the external pressurizing devices connected to the first upper pad 1111, the second upper pad 1211, and the third upper pad 2111 are respectively independently set; the third upper pressure head sleeve 2112 is detachably connected to the lower part of the third upper pad 2111, and a space is provided on the third upper pressure head sleeve 2112 for fixing the upper pressure head spindle 2113; the upper pressure head spindle 2113 has a columnar structure and is made of Cr12MoV material with a quenching hardness of 58 to 62 HRC. The upper pressure head mandrel 2113 is vertically connected to the outer sleeve 2112 of the third upper pressure head, and a threaded hole is opened at the lower end of the upper pressure head mandrel 2113. The toothed mold 2114 has a ring structure and is made of cemented carbide material with a quenching hardness of 70 HRC. The toothed mold 2114 is set at the lower end of the upper pressure head mandrel 2113 and is used to move synchronously with the upper pressure head mandrel 2113 into the cold-rolled steel pipe and extrude internal splines at the target position on the inner wall of the cold-rolled steel pipe. The locking bolt 2115 is an M14 bolt. The locking bolt 2115 passes through the toothed mold 2114 and is threaded into the threaded hole of the upper pressure head mandrel 2113, thereby limiting and locking the toothed mold 2114 at the lower end of the upper pressure head mandrel 2113.

[0116] In a preferred embodiment of this application, an adjustment gap is provided in the horizontal direction between the third upper pressure head sleeve 2112 and the third upper pad 2111, and a first self-aligning screw hole is provided through the side of the third upper pad 2111. A second self-aligning screw hole is provided on the side of the third upper pressure head sleeve 2112, corresponding to the position of the first self-aligning screw hole. A self-aligning bolt 2116 is internally threaded to the first self-aligning screw hole and the second self-aligning screw hole. By turning the self-aligning bolt 2116, the third upper pressure head sleeve 2112 can be moved horizontally relative to the third upper pad 2111, thereby driving the upper pressure head spindle 2113 to move synchronously, achieving the technical effect of finely adjusting the concentricity between the upper pressure head spindle 2113 and the cold-rolled steel pipe.

[0117] The third lower mold 212 includes: a third lower mold cavity 2121, a die 2122, a die outer sleeve 2123, an ejector pin 2124, a third lower pad assembly 2125, and a third lower pressure ring 2126; the third lower mold cavity 2121 is generally cylindrical in shape, and its interior is a space for accommodating the die 2122, the die outer sleeve 2123, the ejector pin 2124, and the third lower pad assembly 2125.

[0118] The die 2122 is located inside the third lower die cavity 2121. The die 2122 has a cylindrical structure and a through hole in its middle that matches the diameter of the cold-rolled steel pipe. The die 2122 is located directly below the upper pressure head mandrel 2113, and the axis of the through hole on the die 2122 is on the same axis as the upper pressure head mandrel 2113. Before extruding the internal spline on the cold-rolled steel pipe, the cold-rolled steel pipe with reduced diameter is placed inside the die 2122. The part of the cold-rolled steel pipe that has not been reduced in diameter is attached to the inner wall of the die 2122. The die 2122 guides the cold-rolled steel pipe so that it is in a vertical position in the third lower die cavity 2121. At the same time, the center hole of the cold-rolled steel pipe is aligned with the upper pressure head mandrel 2113.

[0119] The outer sleeve of the die cavity 2123 is made of 40Cr steel with a tempered hardness of 28 to 32 HRC. The outer sleeve of the die cavity 2123 is fitted on the outside of the die cavity 2122 and abuts against the inner wall of the third lower mold cavity 2121. The outer sleeve of the die cavity 2123 not only serves to fix the die cavity 2122, but also prevents the die cavity 2122 from cracking.

[0120] The ejector pin 2124 is made of Cr12MoV material and has a quenching hardness of 55 to 58 HRC. The ejector pin 2124 is located at the lower end of the third lower die cavity 2121 and is located directly below the die cavity 2122. The lower end of the cold-rolled steel tube inside the die cavity 2122 abuts against the upper surface of the ejector pin 2124. During the process of the toothed die 2114 being pressed into the third lower die 212, the ejector pin 2124 provides support below the cold-rolled steel tube.

[0121] The third lower pad assembly 2125 is disposed inside the third lower die cavity 2121 and abuts against the lower surface of the die cavity 2122 and the die outer sleeve 2123. The third lower pad assembly 2125 includes several annular pads, which are arranged vertically inside the third lower die cavity 2121. The inner diameter of the annular pads matches the outer diameter of the cold-rolled steel pipe and the ejector pin 2124 at the corresponding positions. They are used to fill the gap between the cold-rolled steel pipe, the ejector pin 2124 and the inner wall of the third lower die cavity 2121, thereby fixing the position of the cold-rolled steel pipe and the ejector pin 2124 in the third lower die cavity 2121, thereby improving the overall stability of the third lower die 212 and effectively preventing the cold-rolled steel pipe from shifting laterally during the extrusion of the internal spline.

[0122] The inner diameter of the third lower pressure ring 2126 matches the outer diameter of the third lower mold cavity 2121. The third lower pressure ring 2126 is sleeved on the outside of the third lower mold cavity 2121 to limit the outward expansion of the third lower mold cavity 2121.

[0123] The hollow half-shaft forming equipment provided in this application uses a first diameter reduction mold 11, a second diameter reduction mold 12 and a cold extrusion spline device 2 in combination to directly form a hollow half-shaft by multiple diameter reductions of cold-rolled steel pipes. This optimizes the steps of deep hole processing of the material bar in related technologies, which can reduce material consumption and avoid adverse phenomena such as center hole eccentricity and uneven wall thickness when processing irregular deep holes on the material bar.

[0124] This invention also provides a hollow half-shaft forming method in this embodiment. The forming method uses the hollow half-shaft forming equipment described in the above embodiment. Specifically, the forming method includes the following steps:

[0125] S1: Cold-rolled steel pipes with a blanking diameter of Φ50×Φ30 are used as blanks for hollow half shafts.

[0126] In this step, the cold-rolled steel pipe is made of 40Cr material, which conforms to the standard GB / T3077-2015, and the cutting length is 330 (+0.3 / 0).

[0127] S2: The pre-cut cold-rolled steel pipes are placed in a continuous furnace for normalizing treatment to improve the toughness of the cold-rolled steel pipes.

[0128] In this step, the continuous furnace is heated to 550°C in empty state. The cold-rolled steel pipe is placed into the continuous furnace and heated to 870±5°C. It is then held at this temperature for 2 hours and subsequently removed from the furnace and air-cooled. During this period, the grain size of the normalized structure is grade 5 to 8, and the non-metallic inclusions of types A, B, C, and D are all controlled to be grade 0.5 to 3.

[0129] S3: Shot blasting of cold-rolled steel pipe surface, shot blasting frequency 30Hz, shot blasting time 30min, to passivate the surface of cold-rolled steel pipe and make it honeycomb-like.

[0130] S4: Heat the water tank to 80℃ to 100℃, immerse the cold-rolled steel pipe in the water tank for 10 to 15 minutes until the cold-rolled steel pipe is fully preheated, then hoist it into the first lubricant tank and soak it for 5 to 10 seconds; then hoist the cold-rolled steel pipe and air dry it for 10 minutes, and then let it air dry naturally for 24 hours to ensure that the surface of the cold-rolled steel pipe has a lubricating film layer with a thickness of 20 to 80 μm.

[0131] S5: Place the cold-rolled steel pipe into the first diameter reduction mold for the first diameter reduction.

[0132] In this step, the mandrel 113 is first placed into the cold-rolled steel pipe. The mandrel 113 is positioned axially in the cold-rolled steel pipe by the positioning ring. Then, the mandrel 113 and the cold-rolled steel pipe are placed into the through hole of the first guide cover 1122, and the external pressurization equipment is started to perform the first diameter reduction.

[0133] S6: Place the cold-rolled steel pipe after the first diameter reduction into the second diameter reduction mold for the second diameter reduction.

[0134] In this step, the mandrel 113 is first removed from the cold-rolled steel pipe, and then the cold-rolled steel pipe is placed into the through hole of the second guide cover 1222. The cold-rolled steel pipe is kept in the vertical direction by the straightening component, and the external pressure equipment is started to perform the second diameter reduction.

[0135] S7: Stress-relief tempering of cold-rolled steel pipes; to eliminate the internal stress generated by the two diameter reductions of cold-rolled steel pipes and prevent deformation of cold-rolled steel pipes in subsequent processes due to the release of internal stress.

[0136] In this step, after the cold-rolled steel pipe is placed in the tempering furnace, it is heated to 460℃ and held for 1 hour. After the holding period ends, it is heated to 520℃ and held for 3 hours. After the holding period ends, it is cooled to 400℃±10℃ and then removed from the furnace for air cooling.

[0137] S8: Precision machine the part of the cold-rolled steel pipe to be extruded with internal splines to the preset required dimensions.

[0138] In this step, the cold-rolled steel pipe after stress relief and tempering is precision machined, and the part to be extruded internal spline is precision machined to the size before extrusion. Since the radial extrusion amount S2: the tooth groove area S1≤30%, the internal spline tooth top is filled more fully. Therefore, in this embodiment, the inner diameter of the part to be extruded internal spline on the cold-rolled steel pipe is designed to be Φ31.6.

[0139] S9: Heat the water tank to 80℃ to 100℃, immerse the cold-rolled steel pipe in the water tank for 10 to 15 minutes until the cold-rolled steel pipe is fully preheated, then hoist it into the second lubricant tank and soak it for 5 to 10 seconds; then hoist the cold-rolled steel pipe and air dry it for 10 minutes, and then let it air dry naturally for 24 hours to ensure that the surface of the cold-rolled steel pipe has a lubricating film layer with a thickness of 20 to 80 μm; the second lubricant tank contains a polymer lubricant, the main component of which is graphite.

[0140] S10: Place the cold-rolled steel pipe into the cold extrusion spline device to extrude the internal spline.

[0141] S11: The outer diameter of the cold-rolled steel pipe is precision machined to the preset required size, and the hobbing position of the cold-rolled steel pipe is machined to the center line of the major diameter of the spline.

[0142] S12: Center hole of double-top cold-rolled steel pipe, spline machined by gear hobbing.

[0143] S13: The surface of the cold-rolled steel pipe is quenched by medium-frequency heating to improve the surface hardness and increase the torsional strength; the medium-frequency quenching frequency is 6KHZ to 10KHZ, the current is 82A, and the workpiece speed is 30r / min.

[0144] S14: Grind the outer diameter of the bearing seat on the cold-rolled steel pipe to the preset required size.

[0145] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A hollow half-shaft forming device, characterized in that, include: A graded diameter reduction device is used to gradually reduce the diameter of a hollow half-shaft blank. A cold extrusion spline device, used for extruding internal splines on a hollow half-shaft blank; The graded diameter reduction device includes: The first diameter reduction die is used to extrude the shape of the hollow half shaft onto the hollow half shaft blank. The second diameter reduction die is used to reduce the diameter of the hollow half-shaft blank output by the first diameter reduction die to the target diameter; The first diameter reduction die includes: a first upper die, a first lower die located directly below the first upper die, and a mandrel; wherein, the first upper die is used to press the hollow half-shaft blank into the first lower die for initial diameter reduction, including: The first upper pad is connected to an external pressurizing device; The first upper pressure head cover is detachably connected to the lower part of the first upper pad block, and the first upper pressure head cover has an accommodating space inside; The upper positioning pad is connected to the inside of the first upper pressure head outer sleeve, and the upper positioning pad and the first upper pressure head outer sleeve cooperate to form a mandrel groove; The first lower mold includes: The first diameter reduction die body has a diameter reduction through hole provided on it, and the diameter of the diameter reduction through hole on the first diameter reduction die body gradually decreases from one end face of the first diameter reduction die body to the other end face. The first guide cover has a cylindrical structure and is connected above the first diameter reduction die body. It is used to guide the hollow half-shaft blank and restrict the outward expansion of the hollow half-shaft blank. The first upper pressure ring is connected above the first guide cover and is used to limit the outward expansion of the first guide cover; The first lower die pull ring, the first diameter reduction die body, and the first guide cover are disposed inside the first lower die pull ring; the first lower die pull ring is attached to and pressed against the first upper pressure ring above the first upper pressure ring; The first lower mold cavity is connected directly below the first lower mold pull ring, and an accommodating space is provided inside the first lower mold cavity; The first guide sleeve is disposed inside the first lower mold cavity and located below the first diameter reduction mold body. The position of the first guide sleeve corresponds to the diameter reduction through hole on the first diameter reduction mold body, and is used to correct and straighten the hollow half shaft blank output by the first diameter reduction mold body. The first lower die guide sleeve is sleeved on the outside of the first straight guide sleeve to limit the deformation of the first straight guide sleeve; The first lower pad assembly is disposed inside the first lower mold cavity and is used to fix the first guide sleeve and the first lower mold guide sleeve inside the first lower mold cavity; The first pressing ring is sleeved on the outside of the first lower mold cavity and the first lower mold pull ring, and presses the first lower mold pull ring tightly above the first lower mold cavity; The mandrel limiting clamp is engaged in the mandrel slot, so that the hollow half-shaft blank is positioned at the lower end of the first upper pressure head outer sleeve, and a support is formed inside the hollow half-shaft blank.

2. The hollow half-shaft forming equipment according to claim 1, characterized in that, The mandrel includes: The positioning end is matched in shape and size to the mandrel slot. The support end is a multi-segment columnar structure, the diameter of which gradually decreases from one end near the positioning end to the other end. A positioning ring is provided at the connection between the positioning end and the support end, and the positioning ring is used to mark the axial position of the mandrel in the hollow half-shaft blank.

3. The hollow half-shaft forming equipment according to claim 1, characterized in that, The second diameter reduction die includes: a second upper die and a second lower die located directly below the second upper die; wherein, the second upper die is used to press the hollow half-shaft blank output from the first diameter reduction die into the second lower die for a second diameter reduction, including: The second upper pad is connected to the external pressurization device; The second upper pressure head cover is detachably connected to the lower part of the second upper pad block, and a fixing space is provided at the lower end of the second upper pressure head cover; The upper pressure head has its upper end detachably connected to the fixed space of the second upper pressure head sleeve, and its lower end located below the second upper pressure head sleeve. The lower surface of the upper pressure head is provided with a groove that is adapted to the hollow half-shaft blank. The second lower mold includes: The second diameter reduction die body has a diameter reduction through hole provided on it; the diameter of the diameter reduction through hole on the second diameter reduction die body gradually decreases from one end face of the second diameter reduction die body to the other end face. The second guide cover has a through hole for the hollow half-shaft blank to pass through. The second guide cover is connected to the upper part of the second diameter reduction die body. A straightening component is provided above the second guide cover to keep the hollow half-shaft blank in the second guide cover vertical. The second upper pressure ring is connected above the second guide cover and is used to limit the outward expansion of the second guide cover; The second lower die pull ring, the second diameter reduction die body, and the second guide cover are disposed inside the second lower die pull ring; the second lower die pull ring is attached to and pressed against the second upper pressure ring above the second upper pressure ring; The second lower mold cavity is connected directly below the second lower mold pull ring, and an accommodating space is provided inside the second lower mold cavity; The second guide sleeve is disposed inside the second lower mold cavity and located below the second diameter reduction mold body. The position of the second guide sleeve corresponds to the diameter reduction through hole on the second diameter reduction mold body, and is used to correct and straighten the hollow half shaft blank output by the second diameter reduction mold body. The second lower die guide sleeve is sleeved on the outside of the second guide sleeve and is used to limit the deformation of the second guide sleeve; The second lower pad assembly is disposed inside the second lower mold cavity and is used to fix the second guide sleeve and the second lower mold guide sleeve inside the second lower mold cavity; The second lower pressure ring is sleeved on the outside of the second lower mold cavity and the second lower mold pull ring, so that the second lower mold pull ring and the second lower mold cavity are connected to form a whole.

4. The hollow half-shaft forming equipment according to claim 1, characterized in that, The cold extrusion spline device includes: a third upper die and a third lower die located directly below the third upper die; wherein, the third upper die includes: The third upper pad is connected to an external pressurizing device; The third upper pressure head cover is detachably connected to the lower part of the third upper pad block, and a fixing space is provided on the third upper pressure head cover; The upper pressure head spindle is vertically connected to the fixed space of the third upper pressure head sleeve, and a screw hole is provided at the lower end of the upper pressure head spindle; The tooth mold has a ring structure and is disposed at the lower end of the upper pressure head mandrel, and moves synchronously with the upper pressure head mandrel; A locking bolt passes through the toothed mold and is threaded into the threaded hole of the upper pressure head spindle, thereby limiting and locking the toothed mold to the lower end of the upper pressure head spindle; The third lower mold includes: The third lower mold cavity is cylindrical in shape and has an internal accommodating space. A die is provided in the third lower die cavity. The die has a through hole that matches the diameter of the hollow half-shaft blank, which is used to guide the hollow half-shaft blank into the die. The die is located directly below the upper pressure head mandrel, and the axis of the through hole on the die is on the same axis as the upper pressure head mandrel. A die sleeve is fitted over the outside of the die and abuts against the inner wall of the third lower die cavity to fix the die and prevent it from cracking. A push rod is disposed at the lower end of the third lower mold cavity and located directly below the die cavity, for providing support below the hollow half-shaft blank; The third lower pad assembly is disposed inside the third lower mold cavity and abuts against the lower surface of the die cavity and the die cavity outer sleeve. The third lower pad assembly is used to fill the gap between the hollow half-shaft blank, the ejector rod and the third lower mold cavity, and to fix the hollow half-shaft blank and the ejector rod in the third lower mold cavity. The third pressure ring is sleeved on the outside of the third lower mold cavity to limit the outward expansion of the third lower mold cavity.

5. The hollow half-shaft forming equipment according to claim 4, characterized in that, An adjustment slot is provided horizontally between the third upper pressure head sleeve and the third upper pad. The side of the third upper pad is provided with a first self-aligning screw hole, and the side of the third upper pressure head sleeve is provided with a second self-aligning screw hole corresponding to the position of the first self-aligning screw hole. The first self-aligning screw hole and the second self-aligning screw hole are internally threaded with self-aligning bolts. The self-aligning bolts are used to adjust the relative position of the third upper pressure head sleeve and the third upper pad.

6. The hollow half-shaft forming equipment according to claim 1, characterized in that, The first diameter-reducing die body adopts a double-layer structure of inner and outer molds, including: The inner mold has a reduced diameter through hole on the first reduced diameter mold body located at the center of the end face of the inner mold. An outer mold is fitted over the outer side of the inner mold. The outer mold and the inner mold are joined by heat sealing. The outer mold is used to provide inward prestress to the inner mold.

7. The hollow half-shaft forming equipment according to claim 6, characterized in that, The large end diameter of the through hole on the first diameter reduction die body matches the diameter of the hollow half-shaft blank, and the small end diameter of the through hole on the first diameter reduction die body is 70% to 85% of its large end diameter.

8. A method for forming a hollow half-shaft, characterized in that, Using the hollow half-shaft forming equipment described in claim 1, Includes the following steps: S1: Cold-rolled steel pipes with a blanking diameter of Φ50×Φ30 are used as blanks for hollow half shafts; S2: Place the pre-cut hollow half-shaft blank into a continuous furnace for normalizing treatment; S3: Shot blasting of hollow half-shaft blank surface, shot blasting frequency 30Hz, shot blasting time 30min; S4: After the hollow half-shaft blank is fully preheated, it is hoisted into the first lubricant tank and soaked for 5 to 10 seconds; then the hollow half-shaft blank is hoisted up and air-dried for 10 minutes, and then naturally air-dried for 24 hours to ensure that the surface of the hollow half-shaft blank is covered with a lubricating film layer with a thickness of 20 to 80 μm. S5: Place the hollow half-shaft blank into the first diameter reduction mold for the first diameter reduction; S6: Place the hollow half-shaft blank after the first diameter reduction into the second diameter reduction mold for the second diameter reduction; S7: Stress-relief tempering of hollow half-shaft blanks; S8: Finish machine the part of the hollow half-shaft blank to be extruded internal spline to the preset required size; S9: After the hollow half-shaft blank is fully preheated, it is hoisted into the second lubricant tank and soaked for 5 to 10 seconds; then the hollow half-shaft blank is hoisted up and air-dried for 10 minutes, and then naturally air-dried for 24 hours to ensure that the surface of the hollow half-shaft blank is covered with a lubricating film layer with a thickness of 20 to 80 μm. S10: Place the hollow half-shaft blank into the cold extrusion spline device to extrude the internal spline; S11: The hollow half-shaft blank is precision machined to the preset required size, and the hobbing position size on the hollow half-shaft blank is machined to the center line of the spline major diameter; S12: Center hole of double-top hollow half-shaft blank, spline machined by gear hobbing; S13: The surface of the hollow half-shaft blank is quenched by medium frequency heating. The medium frequency quenching frequency is 6KHZ to 10KHZ, the current is 82A, and the workpiece rotation speed is 30r / min. S14: Grind the bearing position on the hollow half-shaft blank to the preset required size.

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