Forming equipment and method for hollow half shaft

Abstract

The invention discloses a hollow half shaft forming device and method, and belongs to the field of automobile part manufacturing, the hollow half shaft forming device comprises a graded hole shrinkage device, and the graded hole shrinkage device is used for carrying out gradual hole shrinkage on a hollow half shaft blank; the spline cold extrusion device is used for extruding an internal spline on the hollow half shaft blank; the grading hole shrinkage device comprises a first hole shrinkage die, a second hole shrinkage die and a third hole shrinkage die, wherein the first hole shrinkage die is used for extruding the shape of a hollow half shaft on a hollow half shaft blank; the second reducing die is used for reducing and forming the hollow half shaft blank output by the first reducing die to a target diameter; the first reducing die, the second reducing die and the cold extrusion spline device are matched, the cold-rolled steel pipe is used as a hollow half shaft blank for multiple times of reducing forming of the hollow half shaft, material consumption can be reduced, and meanwhile the undesirable phenomena of center hole eccentricity, uneven wall thickness and the like when a special-shaped deep hole is machined in a charge bar can be avoided.

Description

Technical Field

[0001] The present invention relates to the field of automotive parts manufacturing, and more particularly, to a forming device and method for a hollow half shaft. Background Art

[0002] The half shaft of an automobile, also known as the drive shaft, is the shaft that connects the differential to the drive wheels; as a part for transmitting torque in an automobile, there are mandatory requirements for its own torsional strength. In the industry, half shafts are generally made by forging solid shafts and are generally relatively heavy; however, at present, the country advocates energy conservation, emission reduction, and reducing the body weight is the development trend. Solid half shafts obviously can no longer meet the industry development; therefore, the hollowing process of half shafts naturally becomes a cutting-edge technology discussed in the industry.

[0003] The processing steps of a hollow half shaft in related technologies include: receiving bar stock -> rough turning -> deep hole machining -> semi-finish turning -> finish turning; since hollow half shafts are mostly special-shaped pipes with unequal inner diameters, in order to meet the use requirements, it is often necessary to drill special-shaped deep holes with variable hole diameters in the bar stock obtained after rough turning; when using the existing method to process a solid bar stock into a hollow half shaft, due to the large volume of the bar stock blank, the amount of consumables required for forming is large, the raw material utilization rate is low, and the deep hole machining equipment is expensive and the cost is high. The processing of special-shaped deep holes on the bar stock is difficult, and not only are there problems such as central hole eccentricity and uneven wall thickness, but also there are technical problems such as difficult inner hole calibration, ultimately affecting the strength of the half shaft. Summary of the Invention

[0004] The purpose of the present invention is to solve the technical problems of large consumption of consumables and poor forming quality of the central hole when processing and forming a hollow half shaft in the prior art, and to propose a forming device and method for a hollow half shaft.

[0005] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0006] The present invention provides a hollow half shaft forming device in a first aspect, including:

[0007] A stepped necking device, which is used to gradually neck and form a hollow half shaft blank;

[0008] A cold extrusion spline device, which is used to extrude internal splines on the hollow half shaft blank;

[0009] Among them, the stepped necking device includes:

[0010] A first necking die, which is used to extrude the outer shape of the hollow half shaft on the hollow half shaft blank;

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

[0012] Furthermore, the first reducing 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 the first diameter reduction, including:

[0013] A first upper cushion block, which is connected to an external pressurizing device;

[0014] A first upper punch outer sleeve, which is detachably connected below the first upper cushion block, and an accommodation space is arranged inside the first upper punch outer sleeve;

[0015] An upper positioning pad, which is connected inside the first upper punch outer sleeve, and the upper positioning pad and the first upper punch outer sleeve cooperate to form a mandrel clamping groove;

[0016] The first lower die includes:

[0017] A first reducing die main body, on which a reducing through - hole is arranged, and the aperture of the reducing through - hole on the first reducing die main body gradually decreases from one end face of the first reducing die main body to the other end face;

[0018] A first guiding cover, which is in a cylindrical structure, and the first guiding cover is connected above the first reducing die main body, and is used to align the hollow half - shaft blank and limit the outward expansion of the hollow half - shaft blank;

[0019] A first upper pressing ring, which is connected above the first guiding cover, and is used to limit the outward expansion of the first guiding cover;

[0020] A first lower die pulling ring, the first reducing die main body and the first guiding cover are arranged inside the first lower die pulling ring; the first lower die pulling ring is attached to and pressed above the first upper pressing ring;

[0021] A first lower die cavity, which is connected directly below the first lower die pulling ring, and an accommodation space is arranged inside the first lower die cavity;

[0022] A first straightening sleeve, which is arranged inside the first lower die cavity and is located below the first reducing die main body, and the first straightening sleeve corresponds to the position of the reducing through - hole on the first reducing die main body, and is used to correct and straighten the hollow half - shaft blank output by the first reducing die main body;

[0023] A first lower die guiding sleeve, which is sleeved outside the first straightening sleeve, and is used to limit the deformation of the first straightening sleeve;

[0024] The first lower spacer block assembly is arranged inside the first lower die cavity and is used to fix the first straight guide sleeve and the first lower die guide sleeve in the first lower die cavity;

[0025] The first lower pressing ring is sleeved outside the first lower die cavity and the first lower die pulling ring, and presses the first lower die pulling ring above the first lower die cavity;

[0026] The mandrel is limited and clamped in the mandrel card slot, so that the hollow half shaft blank is positioned at the lower end of the first upper pressing head outer sleeve, and a support is formed inside the hollow half shaft blank.

[0027] Further, the mandrel includes:

[0028] A positioning end, the shape and size of which match those of the mandrel card slot;

[0029] A support end, the support end is a multi-segment columnar structure, and its diameter gradually decreases from one end close to the positioning end to the other end;

[0030] Wherein, a positioning ring is arranged 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] Further, the second reducing 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 by the first reducing die into the second lower die for the second reduction, and includes:

[0032] A second upper spacer block, which is connected to an external pressurizing device;

[0033] A second upper pressing head outer sleeve, which is detachably connected below the second upper spacer block, and a fixing space is arranged at the lower end of the second upper pressing head outer sleeve;

[0034] An upper pressing head, the upper end of which is detachably connected in the fixing space of the second upper pressing head outer sleeve, the lower end of which is located below the second upper pressing head outer sleeve, and a card slot adapted to the hollow half shaft blank is arranged on the lower surface of the upper pressing head;

[0035] The second lower die includes:

[0036] A second reducing die main body, on which a reducing through hole is arranged; the aperture of the reducing through hole on the second reducing die main body gradually decreases from one side end face of the second reducing die main body to the other side end face;

[0037] The second guiding cover is provided with a through hole for the hollow half shaft blank to pass through. The second guiding cover is connected above the second reducing die body, and a centering component is arranged above the second guiding cover for keeping the hollow half shaft blank in the second guiding cover vertical.

[0038] The second upper pressing ring is connected above the second guiding cover and is used for restricting the outward expansion of the second guiding cover.

[0039] The second lower die pulling ring, the second reducing die body and the second guiding cover are arranged in the second lower die pulling ring; the second lower die pulling ring is in contact with and pressed above the second upper pressing ring.

[0040] The second lower die cavity is connected directly below the second lower die pulling ring, and an accommodating space is arranged inside the second lower die cavity.

[0041] The second straight guiding sleeve is arranged inside the second lower die cavity and is located below the second reducing die body. The second straight guiding sleeve corresponds to the position of the reducing through hole on the second reducing die body and is used for correcting and guiding the hollow half shaft blank output by the second reducing die body.

[0042] The second lower die guiding sleeve is sleeved outside the second straight guiding sleeve and is used for restricting the deformation of the second straight guiding sleeve.

[0043] The second lower cushion block assembly is arranged inside the second lower die cavity and is used for fixing the second straight guiding sleeve and the second lower die guiding sleeve in the second lower die cavity.

[0044] The second lower pressing ring is sleeved outside the second lower die cavity and the second lower die pulling ring, so that the second lower die pulling ring and the second lower die cavity are connected to form an integral body.

[0045] Further, 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 cushion block is connected to an external pressurizing device.

[0047] The third upper press head outer sleeve is detachably connected below the third upper cushion block, and a fixing space is arranged on the third upper press head outer sleeve.

[0048] The press head core shaft is vertically connected in the fixing space of the third upper press head outer sleeve, and a screw hole is arranged at the lower end of the press head core shaft.

[0049] A tooth mold, the tooth mold has an annular structure, is arranged at the lower end of the upper punch mandrel, and moves synchronously with the upper punch mandrel;

[0050] A locking bolt, the locking bolt passes through the tooth mold and is threadedly connected to the threaded hole of the upper punch mandrel to limit and lock the tooth mold at the lower end of the upper punch mandrel;

[0051] The third lower die includes:

[0052] A third lower die cavity, the third lower die cavity has an overall cylindrical structure, and an accommodating space is arranged inside it;

[0053] A female die, the female die is arranged in the third lower die cavity, and a through hole matching the diameter of the hollow half shaft blank is arranged on the female die for guiding and correcting the hollow half shaft blank entering the female die; the female die is located directly below the upper punch mandrel, and the axis of the through hole on the female die is on the same axis as the upper punch mandrel;

[0054] A female die outer sleeve, the female die outer sleeve is sleeved on the outside of the female die and abuts against the inner wall of the third lower die cavity for fixing the female die to prevent the female die from cracking;

[0055] A ejector rod, the ejector rod is arranged at the lower end of the third lower die cavity and is located directly below the female die for providing support below the hollow half shaft blank;

[0056] A third lower cushion block assembly, the third lower cushion block assembly is arranged inside the third lower die cavity and abuts against the lower surfaces of the female die and the female die outer sleeve. The third lower cushion block assembly is used to fill the gap between the hollow half shaft blank, the ejector rod and the third lower die cavity, and fix the hollow half shaft blank and the ejector rod in the third lower die cavity;

[0057] A third lower pressing ring, the third lower pressing ring is sleeved on the outside of the third lower die cavity for restricting the outward expansion of the third lower die cavity.

[0058] Furthermore, an adjustment gap is provided horizontally between the third upper punch outer sleeve and the third upper cushion block. A through first centering screw hole is provided on the side surface of the third upper cushion block, and a second centering screw hole corresponding to the position of the first centering screw hole is provided on the side surface of the third upper punch outer sleeve. A centering bolt is threadedly connected in the first centering screw hole and the second centering screw hole; the centering bolt is used to adjust the relative position between the third upper punch outer sleeve and the third upper cushion block.

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

[0060] Inner die, the diameter-reducing through hole on the main body of the first diameter-reducing die is opened at the center of the end face of the inner die;

[0061] Outer die, the outer die is sleeved on the outside of the inner die, and the outer die and the inner die are clamped by heat sealing. The outer die is used to provide inward prestress to the inner die.

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

[0063] The 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, including the following steps:

[0064] S1: Cut a cold-rolled steel pipe with a diameter of Φ50×Φ30 as the hollow half-shaft blank;

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

[0066] S3: Shot peening the surface of the hollow half-shaft blank, the shot peening frequency is 30Hz, and the shot peening time is 30Min;

[0067] S4: After the hollow half-shaft blank is fully preheated, lift it into the first lubricant pool and soak it for 5S to 10S; lift the hollow half-shaft blank and air-dry it for 10Min, and then naturally dry it for 24h to ensure that a lubricating film layer with a thickness of 20 to 80μm is obtained on the surface of the hollow half-shaft blank;

[0068] S5: Place the hollow half-shaft blank in the first diameter-reducing die for the first diameter reduction;

[0069] S6: Place the hollow half-shaft blank after the first diameter reduction in the second diameter-reducing die for the second diameter reduction;

[0070] S7: Stress relief annealing of the hollow half-shaft blank;

[0071] S8: Precision turn the part of the hollow half-shaft blank to be extruded with internal splines to the preset required size;

[0072] S9: After the hollow half-shaft blank is fully preheated, lift it into the second lubricant pool and soak it for 5S to 10S; lift the hollow half-shaft blank and air-dry it for 10Min, and then naturally dry it for 24h to ensure that a lubricating film layer with a thickness of 20 to 80μm is obtained on the surface of the hollow half-shaft blank;

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

[0074] S11: Precision turn the outer diameter of the hollow half shaft blank to the preset required size, and machine the size of the hobbing position on the hollow half shaft blank to the center line of the spline major diameter size;

[0075] S12: Double-top the center hole of the hollow half shaft blank and hob the spline;

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

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

[0078] The beneficial effects of the present invention are as follows: A hollow half shaft forming device provided by the present application uses a first reducing die, a second reducing die, and a cold extrusion spline device in cooperation, and directly uses a cold-rolled steel pipe to form the hollow half shaft by multiple reductions, optimizing the steps of deep hole machining of the rod in the related art, that is, it can reduce material consumption, and at the same time can avoid adverse phenomena such as eccentric center holes and uneven wall thickness when machining special-shaped deep holes on the rod. Description of the Drawings

[0079] Figure 1 It is a schematic diagram of the internal structure of the first reducing die in the embodiment of the present invention;

[0080] Figure 2 It is a schematic diagram of the main structure of the first reducing die in the embodiment of the present invention;

[0081] Figure 3 It is a schematic diagram of the internal structure of the second reducing die in the embodiment of the present invention;

[0082] Figure 4 It is a schematic diagram of the structure of the centering component in the embodiment of the present invention;

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

[0084] The markings in the figure are shown as follows:

[0085] 11. First diameter-reducing die; 111. First upper die; 1111. First upper cushion block; 1112. First upper punch outer sleeve; 11121. Core shaft card slot; 1113. Upper positioning pad; 112. First lower die; 1121. First diameter-reducing die body; 11211. Inner die; 11212. Outer die; 1122. First guide cover; 1123. First upper pressure ring; 1124. First lower die pull ring; 1125. First lower die cavity; 1126. First straight guide sleeve; 1127. First lower die guide sleeve; 1128. First lower cushion block assembly; 11281. First lower cushion block; 11282. Second lower cushion block; 11283. Third lower cushion block; 1129. First lower pressure ring; 113. Core shaft; 1131. Positioning end; 1132. Support end;

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

[0087] 2. Cold extrusion spline device; 211. Third upper die; 2111. Third upper cushion block; 2112. Third upper punch outer sleeve; 2113. Upper punch core shaft; 2114. Tooth die; 2115. Locking bolt; 2116. Centering bolt; 212. Third lower die; 2121. Third lower die cavity; 2122. Die; 2123. Die outer sleeve; 2124. Ejector rod; 2125. Third lower cushion block assembly; 2126. Third lower pressure ring. Specific embodiments

[0088] In this embodiment, the hollow half shaft blank is made of pre-treated cold-rolled steel pipe; please refer to Figures 1 to 5 The embodiment of the present application provides a hollow half shaft forming device, which is used to change the overall shape and inner hole diameter of the cold-rolled steel pipe in actual application, so that the cold-rolled steel pipe blank is formed into a hollow half shaft with uniform wall thickness, reducing the weight of the half shaft without reducing the performance, thereby achieving the purpose of energy conservation and emission reduction.

[0089] The hollow half shaft forming device includes: a stepped diameter-reducing device and a cold extrusion spline device 2; the stepped diameter-reducing 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, and the internal splines are engaged with the external splines of the wheel hub to transmit the torque output by the gearbox to the driving wheel.

[0090] Due to the limitation of the material deformation amount, the cold-rolled steel pipe cannot be reduced in diameter to the required size in one step, and the technical solution of successive diameter reduction is adopted in this application; the stepped diameter reduction device includes: a first diameter reduction die 11 and a second diameter reduction die 12; the first diameter reduction die 11 is used to extrude the overall shape of the hollow half shaft on the cold-rolled steel pipe, and the second diameter reduction die is used to reduce the diameter of the cold-rolled steel pipe output by the first diameter reduction die 11 to the target diameter.

[0091] More specifically, please refer to Figure 1 , the first diameter reduction die 11 includes: a first upper die 111, a first lower die 112 and a mandrel 113; wherein, the first upper die 111 includes: a first upper cushion block 1111, a first upper punch outer sleeve 1112 and an upper positioning pad 1113; the first upper cushion block 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 punch outer sleeve 1112 is the main load-bearing component in the first upper die 111, and the first upper punch outer sleeve 1112 is detachably connected below the first upper cushion block 1111. A space for accommodating the upper positioning pad 1113 and the mandrel 113 is provided inside the first upper punch outer sleeve 1112; the upper positioning pad 1113 is connected to the inside of the first upper punch outer sleeve 1112 and forms a mandrel card slot 11121 at the lower end of the first upper punch outer sleeve 1112, the shape and size of which are adapted to the end of the mandrel 113. The upper positioning pad 1113 is used to define the relative position between the mandrel 113 and the first upper punch outer sleeve 1112; the first upper punch outer sleeve 1112 and the upper positioning pad 1113 cooperate to realize the limit fixation of the mandrel 113 on the first upper die 111.

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

[0093] The first lower die 112 is located directly below the first upper die 111 and includes: a first reducing die body 1121, a first guiding cover 1122, a first upper pressing ring 1123, a first lower die pulling ring 1124, a first lower die cavity 1125, a first straight guiding sleeve 1126, a first lower die guiding sleeve 1127, a first lower cushion block assembly 1128, and a first lower pressing ring 1129; the first reducing die body 1121 is integrally in a ring structure, with a reducing through-hole provided in the middle thereof, and the aperture of the reducing through-hole gradually decreases from one end face of the first reducing die body 1121 to the other end face. The large-end diameter of the reducing through-hole on the first reducing die body 1121 matches the cold-rolled steel pipe, and its small-end diameter is 70% to 85% of the large-end diameter. The end face on one side of the first reducing die body 1121 where the large end of the reducing through-hole is located is arranged upward, close to the first upper die 111; the first reducing die body 1121 is the main component for achieving the first reduction effect of the cold-rolled steel pipe. During the process of the reducing part of the cold-rolled steel pipe passing through the reducing through-hole, the outer diameter gradually decreases until the reducing part completely passes through the small end of the reducing through-hole, and the first reduction is completed.

[0094] The first guiding cover 1122 is in a cylindrical structure, with a through-hole provided in the middle thereof through which the cold-rolled steel pipe can pass. The diameter of the through-hole on the first guiding cover 1122 matches the large-end diameter of the reducing through-hole. Annular clamping grooves are respectively arranged at the edges of the two end faces of the first guiding cover 1122. The first reducing die body 1121 is clamped and fixed inside the annular clamping groove on the lower end face of the first guiding cover 1122, and the axis of the reducing through-hole is aligned with the axis of the through-hole on the first guiding cover 1122. The first guiding cover 1122 plays a role in guiding and straightening during the reducing movement of the cold-rolled steel pipe, and at the same time restricts the outward expansion of the cold-rolled steel pipe.

[0095] The first upper pressing ring 1123 is adapted to the shape and size of the annular clamping groove on the upper end face of the first guiding cover 1122 and is clamped and fixed outside the annular clamping groove on the upper end face of the first guiding cover 1122 to further restrict the outward expansion of the first guiding cover 1122 caused by the extrusion of the cold-rolled steel pipe.

[0096] The inner diameter of the first lower die pulling ring 1124 matches the outer diameter of the first upper pressing ring 1123. Raised structures are respectively arranged on the inner wall of the upper end and the outer wall of the lower end of the first lower die pulling ring 1124. The first reducing die body 1121, the first guiding cover 1122, and the first upper pressing ring 1123 are connected inside the first lower die pulling ring 1124, and the first upper pressing ring 1123 is in contact with the inner wall of the first lower die pulling ring 1124. The first lower die pulling ring 1124 is pressed above the first upper pressing ring 1123 through the raised structure on its inner wall.

[0097] The first lower die cavity 1125 is integrally in a tubular structure, and the space inside it is for accommodating the first straight guide sleeve 1126, the first lower die guide sleeve 1127, and the first lower cushion block assembly 1128. One end of the first lower die cavity 1125 is detachably connected to the workbench surface of the press, and the other end is connected directly below the first lower die pull ring 1124, which plays a role in limiting the components in the internal space of the first lower die cavity 1125.

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

[0099] The first lower die guide sleeve 1127 is sleeved outside the first straight guide sleeve 1126 and is used to limit the deformation of the first straight guide sleeve 1126. The first lower cushion block assembly 1128 is arranged inside the first lower die cavity 1125, and it plays a supporting role between the first straight guide sleeve 1126, the press work platform, and the first lower die cavity 1125, making the positions of the first straight guide sleeve 1126 and the first lower die guide sleeve 1127 fixed in the first lower die cavity 1125. By filling the gap inside the first lower die cavity 1125 with the first lower cushion block 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 the damage of the first straight guide sleeve 1126 caused by stress imbalance.

[0100] The inner diameter of the first lower pressing ring 1129 matches the outer diameter of the first lower die cavity 1125. The inner wall of the first lower pressing ring 1129 is provided with a convex structure that cooperates with the first lower die pull ring 1124. The first lower pressing ring 1129 is sleeved outside the first lower die cavity 1125 and the first lower die pull ring 1124, and the convex structure on the inner wall of the first lower pressing ring 1129 abuts against the convex structure on the outer wall of the first lower die pull ring 1124, thereby pressing the first lower die pull ring 1124 tightly above the first lower die cavity 1125 and connecting the first lower die pull ring 1124 and the first lower die cavity 1125 to form an integral body.

[0101] In the above technical solution, the first lower spacer block assembly 1128 is made of 40Cr material with a hardness of 28 to 32 HRC, and it includes: a first lower spacer block 11281, a second lower spacer block 11282, and a third lower spacer block 11283; the first lower spacer block 11281, the second lower spacer block 11282, and the third lower spacer block 11283 are all of cylindrical structures, and the outer diameters match the inner diameter of the first lower die cavity 1125; among them, the first lower spacer block 11281 is located at the bottom of the first lower die cavity 1125, and is used to adjust the height of the first straightening sleeve 1126 and bear the pressure transmitted by the upper components; the second lower spacer block 11282 is placed above the first lower spacer block 11281 and below the first lower die guiding sleeve 1127. A limiting groove for clamping the first straightening sleeve 1126 is provided at the central position of the upper end face of the second lower spacer block 11282. The first straightening sleeve 1126 is limited and fixed between the second lower spacer block 11282 and the first reducing die main body 1121. The function of the second lower spacer block 11282 is to limit the position of the first straightening sleeve 1126 in the first lower die cavity 1125; a through hole matching the outer diameter of the first straightening sleeve 1126 is provided in the middle of the third lower spacer block 11283. The third lower spacer block 11283 is sleeved outside the first straightening sleeve 1126. The upper end of the third lower spacer block 11283 abuts against the lower surface of the first reducing die main body 1121, and its lower end abuts against the upper surface of the first lower die guiding sleeve 1127, and cooperates with the second lower spacer block 11282 to press and fix the first lower die guiding sleeve 1127.

[0102] As a preferred embodiment of the present application, please refer to Figure 2 , the first reducing die main body 1121 adopts a double-layer structure of inner and outer dies, including: an inner die 11211 and an outer die 11212; the inner die 11211 is made of cemented carbide material, and a reducing through hole is opened at the central position of the end face of the inner die 11211. The inner surface of the reducing through hole is polished with a roughness Ra within 0.2; the outer die 11212 is sleeved outside the inner die 11211, made of 40Cr material with a hardness of 28 to 32 HRC. The outer die 11212 and the inner die 11211 are combined by a hot bonding method, and the contour joints are smoothly transitioned; the outer die 11212 provides an inward prestress for the inner die 11211 to ensure that the inner die 11211 can apply sufficient clamping force to the cold-rolled steel pipe and prevent the inner die 11211 from being cracked by the cold-rolled steel pipe during the reducing process.

[0103] The mandrel 113 is made of 40Cr material with a quenched and tempered hardness of 28 to 32 HRC. A DLC coating is provided on the surface of the mandrel 113 to increase hardness and reduce the friction coefficient. More specifically, the mandrel 113 includes a positioning end 1131 and a supporting end 1132. The length and diameter of the positioning end 1131 of the mandrel 113 match the mandrel slot 11121 on the first upper press head outer sleeve 1112. The mandrel 113 is limited and clamped to the lower end of the first upper press head outer sleeve 1112 by connecting the positioning end 1131 to the mandrel slot 11121. The supporting end 1132 is a multi-segment columnar structure, and its diameter gradually decreases from one end close to the positioning end 1131 to the other end. In this embodiment, the supporting end 1132 of the mandrel 113 is provided with two segments. Among them, the diameter of one segment close to the positioning end 1131 matches the diameter of the cold-rolled steel pipe, and the diameter of the other segment far from the positioning end 1131 is the target inner diameter of the cold-rolled steel pipe after the first diameter reduction. The two segments of the supporting end 1132 are smoothly transitioned. The supporting end 1132 is used to provide support inside the cold-rolled steel pipe, so that the area of the cold-rolled steel pipe under support is extruded and extended during the first diameter reduction process, the inner diameter of the cold-rolled steel pipe is reduced to the target size, and the wall thickness of the extruded and extended part of the cold-rolled steel pipe remains uniform. A positioning ring is provided at the connection between the positioning end 1131 and the supporting 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 orifice of the cold-rolled steel pipe, it means 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] As an implementation mode of the present application, the hollow half-shaft blank is a cold-rolled steel pipe with a diameter of Φ50×Φ30mm and a length of 330mm, and the material is 40Cr. The diameter of the positioning end 1131 of the mandrel 113 is 30mm, and the diameter of the supporting end 1132 is 24mm. The large end diameter of the reducing through hole on the main body 1121 of the first reducing die is 50mm, and the small end diameter is 41.5mm; when the cold-rolled steel pipe is first reduced in diameter, first insert the mandrel 113 from the upper end of the cold-rolled steel pipe and position it, insert the lower end of the cold-rolled steel pipe into the first guiding cover 1122, and straighten the cold-rolled steel pipe through the first guiding cover 1122. At this time, start the external pressurizing device. The first upper die 111 moves closer to the mandrel 113 as a whole, and the positioning end 1131 of the mandrel 113 is limited and fixed in the mandrel card slot 11121, and the cold-rolled steel pipe abuts against the lower surface of the first upper pressure head outer sleeve 1112; the external pressurizing device continues to apply pressure, presses the reduced-diameter part of the cold-rolled steel pipe into the main body 1121 of the first reducing die, passes through the main body 1121 of the first reducing die and enters the reduced-diameter part of the first straightening sleeve 1126 to complete the first reduction in diameter. The external pressurizing device presses down until the cold-rolled steel pipe is completely pressed into the first lower die 112; the outer diameter of the cold-rolled steel pipe after the first reduction in diameter at the reduced-diameter part is 41.5mm, the inner diameter is 24mm, and the wall thickness is 8.75mm; the design purpose of the first reducing die 11 is to perform preliminary reduction in diameter at a specified part of the cold-rolled steel pipe to form the shape of the hollow half-shaft of the cold-rolled steel pipe, so that the subsequent second reducing die 12 can reduce the cold-rolled steel pipe to the target size on this basis.

[0105] In order to further reduce the diameter of the cold-rolled steel pipe output by the first reducing die 11 to the required size, please refer to Figure 3 , the second reducing die 12 includes: a second upper die 121 and a second lower die 122; among them, the second upper die 121 includes: a second upper cushion block 1211, a second upper pressure head outer sleeve 1212 and an upper pressure head 1213; the second upper cushion block 1211 is connected to the external pressurizing device and is used to transmit the pressure applied by the external pressurizing device. In this embodiment, the external pressurizing device connected to the first upper cushion block 1111 and the external pressurizing device connected to the second upper cushion block 1211 are independently arranged respectively; the second upper pressure head outer sleeve 1212 is detachably connected to the lower part of the second upper cushion block 1211, and a space for fixing the upper pressure head 1213 is arranged at the lower end of the second upper pressure head outer sleeve 1212; the upper pressure head 1213 is the main load-bearing component in the second upper die 121, and its cross-section is a T-shaped structure. The upper pressure head 1213 is made of Cr12MoV material, and the heat treatment hardness is 58 to 62HRC; the upper end of the upper pressure head 1213 is detachably connected to the inside 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. A card slot adapted to the shape of the end of the cold-rolled steel pipe is provided on the lower surface of the upper pressure head 1213; the cold-rolled steel pipe is limited and fixed to the upper pressure head 1213 by being clamped in the card slot on the lower surface of the upper pressure head 1213.

[0106] The second lower die 122 includes: a second reducing die body 1221, a second guiding cover 1222, a second upper pressing ring 1223, a second lower die pulling ring 1224, a second lower die cavity 1225, a second straight guiding sleeve 1226, a second lower die guiding sleeve 1227, a second lower cushion block assembly 1228, and a second lower pressing ring 1229; a reducing through hole is arranged in the middle of the second reducing die body 1221, and the aperture of the reducing through hole on the second reducing die body 1221 gradually decreases from one end face of the second reducing die body 1221 to the other end face, wherein the large end diameter of the reducing through hole on the second reducing die body 1221 matches the diameter of the non-reduced part of the cold-rolled steel pipe; the second reducing die body 1221 is the main component for realizing the second reducing effect of the cold-rolled steel pipe. When the reduced part of the cold-rolled steel pipe moves in the reducing through hole of the second reducing die body 1221, the outer diameter is reduced again until the reduced part of the cold-rolled steel pipe completely passes through the small end of the reducing through hole, and the second reduction is completed; at this time, the diameter of the cold-rolled steel pipe matches the target diameter of the hollow half shaft; it can be understood from the structure of the first reducing die body 1121 that the second reducing die body 1221 also adopts a double-layer structure of an inner die and an outer die.

[0107] A through hole through which the cold-rolled steel pipe can pass is arranged in the middle of the second guiding cover 1222, and the diameter of the through hole on the second guiding cover 1222 matches the large end diameter of the reducing through hole on the second reducing die body 1221. The second guiding cover 1222 is connected above the second reducing die body 1221, and the cold-rolled steel pipe passes through the second guiding cover 1222 and enters the second reducing die body 1221 for reducing; since the cold-rolled steel pipe obtained after the first reduction is a special-shaped pipe with a changing outer diameter, when the cold-rolled steel pipe moves in the through hole of the second guiding cover 1222, there is a gap between its reduced part and the second guiding cover 1222, which will cause the cold-rolled steel pipe to pass through the second guiding cover 1222 in an inclined posture and insert into the second reducing die body 1221, ultimately affecting the quality of the second reduction forming of the cold-rolled steel pipe; in the above technical solution, a straightening component is arranged above the second guiding cover 1222, and the straightening component is used to keep the cold-rolled steel pipe in the correct axial position in the second guiding cover 1222; please refer to Figure 4, the alignment component includes: a pressure plate 12221, a slider 12222, and a spring clamp 12223; the longitudinal section of the pressure plate 12221 is in a U-shaped structure, the pressure plate 12221 is detachably connected to the upper surface of the second guide cover 1222 by bolts, and a track for accommodating the slider 12222 is formed between the pressure plate 12221 and the second guide cover 1222. A through hole corresponding to the position of the second guide cover 1222 and large enough for a cold-rolled steel pipe to pass through is provided in the middle of the pressure plate 12221; the slider 12222 is located between the pressure plate 12221 and the second guide cover 1222, and the three-piece 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-piece slider 12222, causing the three-piece slider 12222 to move along the track and approach each other; with the design of the alignment component, during the movement of the cold-rolled steel pipe within the second guide cover 1222, the slider 12222 can move radially in a scaling manner, changing the distance between the three-piece sliders 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 remains in 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 outward expansion of the second guide cover 1222 caused by the extrusion of the cold-rolled steel pipe.

[0109] The second diameter-reducing 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 fits with the second upper pressure ring 1223, and the second lower die pull ring 1224 presses above the second upper pressure ring 1223.

[0110] The inside of the second lower die cavity 1225 is a space for accommodating the second straightening sleeve 1226, the second lower die guide sleeve 1227, and the second lower cushion block assembly 1228. The upper end of the second lower die cavity 1225 is connected directly below the second lower die pull ring 1224. The second lower die cavity 1225 and the second lower die pull ring 1224 cooperate to limit the components within the second lower die 122.

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

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

[0113] The inner diameter of the second lower pressure ring 1229 matches the outer diameter of the second lower die cavity 1225. The second lower pressure ring 1229 is sleeved on the outside of the second lower die cavity 1225 and the second lower die pull ring 1224, and is located at the connecting position of the second lower die cavity 1225 and the second lower die pull ring 1224, so that the second lower die pull ring 1224 is connected to the second lower die cavity 1225 to form a whole, thereby preventing them from being misaligned with each other.

[0114] As an implementation mode of the present application, the large end diameter of the reduction hole on the second reduction die main body 1221 is 50 mm, and the small end diameter is 34 mm; after the first reduction of the cold-rolled steel pipe is completed, the reduced diameter portion of the cold-rolled steel pipe is inserted into the second guide cover 1222, and the cold-rolled steel pipe is clamped and straightened by the straightening assembly, and the second upper die 121 is controlled to approach the second lower die 122, and the upper end of the cold-rolled steel pipe is limited to abut against the groove on the lower surface of the upper pressure head 1213, and the second upper die 121 continues to approach the second lower die 122 to press the reduced diameter portion of the cold-rolled steel pipe into The second reducing die body 1221 passes through the second reducing die body 1221 and enters the reducing part of the second guide sleeve 1226 to complete the second reducing. 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 reducing part of the cold-rolled steel pipe after the second reducing is 24 mm. After the step-by-step reducing, the diameter of the cold-rolled steel pipe can reach the target size, and the above scheme optimizes the deep hole processing steps in the traditional process, effectively avoiding the occurrence of undesirable phenomena such as eccentricity of the center hole and uneven wall thickness.

[0115] To continue extruding the internal splines in the cold rolled steel tube for engagement with the external splines of the wheel hub, please refer to Figure 5, in the above technical solution, the cold extrusion spline device 2 includes: a third upper die 211 and a third lower die 212; among them, the third upper die 211 includes: a third upper cushion block 2111, a third upper punch outer sleeve 2112, a punch core shaft 2113, a tooth die 2114, and a locking bolt 2115; the third upper cushion block 2111 has a concave structure and is connected to an external pressurizing device for transmitting the pressure applied by the external pressurizing device. In this embodiment, the external pressurizing devices corresponding to the first upper cushion block 1111, the second upper cushion block 1211, and the third upper cushion block 2111 are independently arranged; the third upper punch outer sleeve 2112 is detachably connected below the third upper cushion block 2111, and a space for fixing the punch core shaft 2113 is provided on the third upper punch outer sleeve 2112; the punch core shaft 2113 is integrally columnar, made of Cr12MoV material with a quenched hardness of 58 to 62 HRC. The punch core shaft 2113 is vertically connected in the third upper punch outer sleeve 2112, and a threaded hole is opened at the lower end of the punch core shaft 2113; the tooth die 2114 is integrally annular, made of cemented carbide material with a quenched hardness of 70 HRC. The tooth die 2114 is arranged at the lower end of the punch core shaft 2113 for synchronously moving with the punch core shaft 2113 into the cold-rolled steel pipe and extruding 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 tooth die 2114 and is threadedly connected to the threaded hole of the punch core shaft 2113, thereby limiting and locking the tooth die 2114 at the lower end of the punch core shaft 2113.

[0116] As a preferred embodiment of the present application, an adjustment gap is provided horizontally between the third upper punch outer sleeve 2112 and the third upper cushion block 2111. A through first centering screw hole is provided on the side of the third upper cushion block 2111, and a second centering screw hole corresponding to the position of the first centering screw hole is provided on the side of the third upper punch outer sleeve 2112. A centering bolt 2116 is threadedly connected in the first centering screw hole and the second centering screw hole; by screwing the centering bolt 2116, the third upper punch outer sleeve 2112 can be horizontally moved relative to the third upper cushion block 2111, thereby driving the punch core shaft 2113 to move synchronously, achieving the technical effect of fine-tuning the concentricity between the punch core shaft 2113 and the cold-rolled steel pipe.

[0117] The third lower die 212 includes: a third lower die cavity 2121, a female die 2122, a female die outer sleeve 2123, a push rod 2124, a third lower cushion block assembly 2125, and a third lower pressing ring 2126; the third lower die cavity 2121 is integrally cylindrical, and the space inside it is for accommodating the female die 2122, the female die outer sleeve 2123, the push rod 2124, and the third lower cushion block assembly 2125.

[0118] The female die 2122 is arranged in the third lower die cavity 2121. The female die 2122 is of a cylindrical structure, and a through hole matching the diameter of the cold-rolled steel pipe is provided in the middle thereof. The female die 2122 is located directly below the upper punch mandrel 2113, and the axis of the through hole on the female die 2122 is on the same axis as the upper punch mandrel 2113. Before internal spline extrusion of the cold-rolled steel pipe, the cold-rolled steel pipe with diameter reduction completed is placed in the female die 2122, and the non-diameter-reduced part of the cold-rolled steel pipe is attached to the inner wall of the female die 2122, so as to align the cold-rolled steel pipe through the female die 2122, make the cold-rolled steel pipe in a vertical state in the third lower die cavity 2121, and at the same time, the central hole of the cold-rolled steel pipe is aligned with the upper punch mandrel 2113.

[0119] The outer sleeve of the female die 2123 is made of 40Cr steel quenched and tempered material, and the quenched and tempered hardness is 28 to 32 HRC. The outer sleeve of the female die 2123 is sleeved on the outside of the female die 2122 and abuts against the inner wall of the third lower die cavity 2121. The outer sleeve of the female die 2123 not only plays a role in fixing the female die 2122, but also can prevent the female die 2122 from cracking.

[0120] The ejector rod 2124 is made of Cr12MoV material, and the quenched hardness is 55 to 58 HRC. The ejector rod 2124 is arranged at the lower end of the third lower die cavity 2121 and is located directly below the female die 2122. The lower end of the cold-rolled steel pipe in the female die 2122 abuts against the upper surface of the ejector rod 2124. During the process of pressing the tooth die 2114 into the third lower die 212, the ejector rod 2124 provides support below the cold-rolled steel pipe.

[0121] The third lower cushion block assembly 2125 is arranged inside the third lower die cavity 2121 and abuts against the lower surfaces of the female die 2122 and the outer sleeve of the female die 2123. The third lower cushion block assembly 2125 includes a number of annular cushion blocks. The number of annular cushion blocks is arranged vertically in the third lower die cavity 2121. The inner diameter of the annular cushion block matches the outer diameters of the cold-rolled steel pipe and the ejector rod 2124 at the corresponding positions, and is used to fill the gaps between the cold-rolled steel pipe, the ejector rod 2124 and the inner wall of the third lower die cavity 2121, so that the cold-rolled steel pipe and the ejector rod 2124 are fixed in position in the third lower die cavity 2121, thereby improving the overall stability of the third lower die 212 and effectively avoiding lateral offset of the cold-rolled steel pipe during the process of internal spline extrusion.

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

[0123] A hollow half - shaft forming device provided by the present application uses a first reducing die 11, a second reducing die 12 and a cold - extrusion spline device 2 in cooperation, directly forming a hollow half - shaft by reducing the diameter of a cold - rolled steel pipe multiple times, optimizing the steps of deep - hole machining of a material rod in the related technology, that is, it can reduce material consumption and avoid adverse phenomena such as center - hole eccentricity and uneven wall thickness when machining special - shaped deep holes on the material rod.

[0124] The present invention also provides a method for forming a hollow half - shaft in this embodiment. The forming method uses the hollow half - shaft forming device in the above - mentioned embodiment. Specifically, the steps of the forming method include:

[0125] S1: Cut a cold - rolled steel pipe with a diameter of Φ50×Φ30 as the blank of the hollow half - shaft.

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

[0127] S2: Put the cut cold - rolled steel pipe into a continuous furnace for normalizing treatment to improve the toughness of the cold - rolled steel pipe.

[0128] In this step, the continuous furnace is heated from an empty furnace to 550℃. After the cold - rolled steel pipe is put into the continuous furnace and heated to 870±5℃ with the furnace, it is kept warm for 2h, and then taken out of the furnace and air - cooled. During this period, the grain size of the normalized structure is from grade 5 to grade 8, and the non - metallic inclusions of types A, B, C, and D are all controlled between grade 0.5 and grade 3.

[0129] S3: Shot - blast the surface of the cold - rolled steel pipe. The shot - blasting frequency is 30Hz, and the shot - blasting time is 30Min, making the surface of the cold - rolled steel pipe passivated and in a honeycomb shape.

[0130] S4: Heat the water pool to 80℃ to 100℃. Immerse the cold - rolled steel pipe in the water pool for 10 to 15Min. After the cold - rolled steel pipe is fully pre - heated, lift it into the first lubricant pool and soak it for 5S to 10S; then lift the cold - rolled steel pipe and air - dry it for 10Min, and then let it dry naturally for 24h to ensure that a lubricating film layer with a thickness of 20 to 80μm is formed on the surface of the cold - rolled steel pipe.

[0131] S5: Put the cold - rolled steel pipe into the first reducing die for the first diameter reduction.

[0132] In this step, first put the mandrel 113 into the cold - rolled steel pipe. The mandrel 113 positions its axial position in the cold - rolled steel pipe through a positioning ring. Then put the mandrel 113 and the cold - rolled steel pipe into the through - hole of the first guide cover 1122, and start the external pressurizing device for the first diameter reduction.

[0133] S6: Put the cold - rolled steel pipe after the first diameter reduction into the second reducing die for the second diameter reduction.

[0134] In this step, first, the mandrel 113 is withdrawn from the cold-rolled steel pipe, and then the cold-rolled steel pipe is placed into the through-hole of the second guiding cover 1222. The cold-rolled steel pipe is kept in the vertical direction by the centering component, and the external pressurizing device is started for the second diameter reduction.

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

[0136] In this step, after the cold-rolled steel pipe is placed in the tempering furnace, it is heated up to 460 °C with the furnace, held for 1 h, and after the holding is completed, it continues to be heated up to 520 °C with the furnace and held for 3 h. After the holding is completed, it is cooled with the furnace to 400 °C ± 10 °C and then taken out of the furnace for air cooling.

[0137] S8: Precision turning the part of the cold-rolled steel pipe where the internal splines are to be extruded to the preset required size.

[0138] In this step, the cold-rolled steel pipe after stress relief annealing is subjected to finish machining, and the part where the internal splines are to be extruded is precision turned to the size before extrusion; since when the radial extrusion amount S2: the tooth groove area S1 ≤ 30%, the filling of the internal spline tooth top is relatively full, so in this embodiment, the designed inner diameter size of the part of the cold-rolled steel pipe where the internal splines are to be extruded is Φ31.6.

[0139] S9: Heat the water pool to 80 °C to 100 °C, immerse the cold-rolled steel pipe in the water pool for 10 to 15 min. After the cold-rolled steel pipe is fully preheated, it is lifted into the second lubricant pool and soaked for 5 s to 10 s; then the cold-rolled steel pipe is lifted and air-dried for 10 min, and then naturally dried for 24 h to ensure that a lubricating film layer with a thickness of 20 to 80 μm is obtained on the surface of the cold-rolled steel pipe; the second lubricant pool contains a polymer lubricant, and the main component is graphite.

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

[0141] S11: Precision turning the outer circle of the cold-rolled steel pipe to the preset required size, and machining the size of the hobbing position on the cold-rolled steel pipe to the center line of the spline major diameter size.

[0142] S12: Double-top the center hole of the cold-rolled steel pipe and hob the splines.

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

[0144] S14: Grind the bearing position on the cold-rolled steel pipe and the outer circle to the preset required size.

[0145] The above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, making equivalent substitutions or changes should be covered within the protection scope of the present invention.

Claims

1. A hollow half-shaft forming device, characterized in that: include: A step-by-step shrinking device, which is used to shrink the hollow half-shaft blank in succession; A cold extrusion spline device, wherein the cold extrusion spline device is used to extrude internal splines on a hollow half-shaft blank; Wherein, the graded diameter reduction device comprises: A first diameter reduction die, wherein the first diameter reduction die is used to extrude the outer shape of the hollow half-axle on the hollow half-axle blank; The second reducing die is used to reduce the diameter of the hollow semi-axle blank output by the first reducing die to a target diameter.

2. A hollow half-shaft forming device according to claim 1, characterized in that: The first diameter reduction die comprises: 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 semi-axle blank into the first lower die for the first diameter reduction, and comprises: a first upper pad, the first upper pad being connected to an external pressurizing device; A first upper pressing head jacket, wherein the first upper pressing head jacket is detachably connected to the lower side of the first upper cushion block, and an accommodating space is provided inside the first upper pressing head jacket; An upper positioning pad, the upper positioning pad is connected to the interior of the first upper pressure head housing, and the upper positioning pad cooperates with the first upper pressure head housing to form a mandrel slot; The first lower mold comprises: A first diameter reduction die body, wherein a diameter reduction through hole is provided on the first diameter reduction die body, and the diameter of the diameter reduction through hole on the first diameter reduction die body gradually decreases from one end surface of the first diameter reduction die body to the other end surface; A first guide cover, which is a cylindrical structure and connected to the upper part of the first diameter reduction die body, and is used for guiding the hollow semi-axle blank and limiting the outward expansion of the hollow semi-axle blank; A first upper pressure ring, 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; A first lower die pull ring, the first diameter reducing die body and the first guide cover are arranged in the first lower die pull ring; the first lower die pull ring is attached to the first upper pressure ring and pressed tightly on the first upper pressure ring; A first lower die cavity, wherein the first lower die cavity is connected to the lower portion of the first lower die pull ring, and an accommodating space is provided inside the first lower die cavity; A first straightening sleeve, which is arranged inside the first lower die cavity and below the first diameter reduction die body, and corresponds to the position of the diameter reduction through hole on the first diameter reduction die body, and is used to correct and straighten the hollow semi-shaft blank output by the first diameter reduction die body; A first lower die guide sleeve, which is sleeved on the outer side of the first straight guide sleeve and is used to limit the deformation of the first straight guide sleeve; A first lower pad assembly, which is disposed inside the first lower die cavity and is used to fix the first straight guide sleeve and the first lower die guide sleeve in the first lower die cavity; A first lower pressure ring, wherein the first lower pressure ring is sleeved on the outer sides of the first lower die cavity and the first lower die pull ring, and presses the first lower die pull ring tightly on the upper side of the first lower die cavity; The mandrel limiter is clamped in the mandrel clamping groove, so that the hollow half-shaft blank is positioned at the lower end of the first upper pressure head sleeve and forms a support inside the hollow half-shaft blank.

3. A hollow half-shaft forming device according to claim 2, characterized in that: The mandrel comprises: A positioning end, the shape and size of which match the mandrel slot; A supporting end, wherein the supporting end is a multi-section columnar structure, and the diameter thereof decreases gradually from one end close to the positioning end to the other end; Wherein, a positioning ring is provided at the connection between the positioning end and the supporting end, and the positioning ring is used to mark the axial position of the core shaft in the hollow half-shaft blank.

4. The hollow half-shaft forming device according to claim 1, characterized in that: The second diameter reduction die comprises: 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 semi-axle blank outputted by the first diameter reduction die into the second lower die for a second diameter reduction, comprising: a second upper pad, the second upper pad being connected to an external pressurizing device; A second upper pressure head jacket, wherein the second upper pressure head jacket is detachably connected to the lower side of the second upper cushion block, and a fixed space is arranged at the lower end of the second upper pressure head jacket; An upper pressing head, wherein the upper end of the upper pressing head is detachably connected to the fixed space of the second upper pressing head housing, and the lower end of the upper pressing head is located below the second upper pressing head housing, and a slot adapted to the hollow half-axle blank is provided on the lower surface of the upper pressing head; The second lower mold comprises: A second diameter reduction die body, wherein a diameter reduction through hole is arranged on the second diameter reduction die body; the diameter of the diameter reduction through hole on the second diameter reduction die body gradually decreases from one end surface of the second diameter reduction die body to the other end surface; A second guide cover, wherein a through hole is provided on the second guide cover for allowing the hollow semi-axle blank to pass through, the second guide cover is connected to the upper part of the second diameter reduction die body, and a straightening assembly is provided above the second guide cover for keeping the hollow semi-axle blank in the second guide cover vertical; A second upper pressure ring, the second upper pressure ring is connected to the upper part of the second guide cover and is used to limit the outward expansion of the second guide cover; A second lower die pull ring, the second diameter reducing die body and the second guide cover are arranged in the second lower die pull ring; the second lower die pull ring is attached to the second upper pressure ring and pressed tightly on the second upper pressure ring; a second lower die cavity, wherein the second lower die cavity is connected to the lower portion of the second lower die pull ring, and a receiving space is provided inside the second lower die cavity; A second straightening sleeve, which is arranged inside the second lower die cavity and below the second diameter reduction die body, and corresponds to the position of the diameter reduction through hole on the second diameter reduction die body, and is used to correct and straighten the hollow semi-shaft blank output by the second diameter reduction die body; A second lower die guide sleeve, wherein the second lower die guide sleeve is sleeved on the outer side of the second straight guide sleeve and is used to limit the deformation of the second straight guide sleeve; A second lower pad assembly, the second lower pad assembly is disposed inside the second lower die cavity and is used to fix the second straight guide sleeve and the second lower die guide sleeve in the second lower die cavity; The second lower pressure ring is sleeved on the outer sides of the second lower die cavity and the second lower die pull ring, so that the second lower die pull ring is connected to the second lower die cavity to form a whole.

5. The hollow half-shaft forming device according to claim 1, characterized in that: The cold extrusion spline device comprises: a third upper die and a third lower die located directly below the third upper die; wherein the third upper die comprises: a third upper pad, the third upper pad being connected to an external pressurizing device; A third upper pressure head jacket, wherein the third upper pressure head jacket is detachably connected to the lower side of the third upper cushion block, and a fixed space is arranged on the third upper pressure head jacket; An upper press head core shaft, the upper press head core shaft is vertically connected to the fixed space of the third upper press head housing, and a screw hole is arranged at the lower end of the upper press head core shaft; The tooth mold is an annular structure, which is arranged at the lower end of the upper pressure head core shaft and moves synchronously with the upper pressure head core shaft; A locking bolt, which passes through the tooth die and is threadedly connected to a screw hole of the upper pressure head mandrel to limit and lock the tooth die to the lower end of the upper pressure head mandrel; The third lower mold comprises: A third lower mold cavity, the third lower mold cavity is an overall cylindrical structure, and a containing space is arranged inside the third lower mold cavity; A concave die, the concave die is arranged in the third lower die cavity, a through hole matching the diameter of the hollow semi-axle blank is arranged on the concave die, and used to guide the hollow semi-axle blank entering the concave die; the concave die is located directly below the core shaft of the upper ram, and the axis center of the through hole on the concave die is on the same axis as the core shaft of the upper ram; A female mold outer sleeve, which is sleeved on the outer side of the female mold and abuts against the inner wall of the third lower mold cavity, and is used to fix the female mold to prevent the female mold from cracking; A push rod, which is arranged at the lower end of the third lower die cavity and is located directly below the female die, and is used to provide support below the hollow semi-axle blank; A third lower pad assembly, which is disposed inside the third lower die cavity and abuts against the lower surfaces of the die and the die jacket, and is used to fill the gap between the hollow semi-axle blank, the ejector rod and the third lower die cavity, and fix the hollow semi-axle blank and the ejector rod in the third lower die cavity; A third lower pressure ring is sleeved on the outer side of the third lower die cavity and is used for limiting the outward expansion of the third lower die cavity.

6. The hollow half-shaft forming device according to claim 5, characterized in that: An adjustment gap is left in the horizontal direction between the third upper pressure head sleeve and the third upper pad, a first centering screw hole is provided through the side of the third upper pad, a second centering screw hole corresponding to the position of the first centering screw hole is provided on the side of the third upper pressure head sleeve, and the first centering screw hole and the second centering screw hole are internally threadedly connected with an centering bolt; the centering bolt is used to adjust the relative position of the third upper pressure head sleeve and the third upper pad.

7. The hollow half-shaft forming device according to claim 2, characterized in that: The first diameter reduction die body adopts an inner and outer die double-layer structure, including: Inner mold, the reducing through hole on the first reducing mold body is opened at the center position of the end surface of the inner mold; The outer mold is sleeved on the outer side of the inner mold, the outer mold and the inner mold are closed by heat sealing, and the outer mold is used to provide inward prestress to the inner mold.

8. The hollow semi-axle forming device according to claim 7, characterized in that: The large end diameter of the reduction hole on the first reduction die body matches the diameter of the hollow semi-shaft blank, and the small end diameter of the reduction hole on the first reduction die body is 70% to 85% of the large end diameter thereof.

9. A method for forming a hollow semi-axle, characterized in that: Using the hollow half-shaft forming equipment described in claim 1, The following steps are involved: S1: Cutting the cold-rolled steel tube with a diameter of Φ50×Φ30 as the hollow half-axle blank; S2: Put the cut hollow half-axle blank into a continuous furnace for normalizing treatment; S3: Shot blasting of the surface of the hollow semi-axle blank, 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 pool and soaked for 5S to 10S; the hollow half-shaft blank is hoisted to air-dry for 10Min, and then naturally dried for 24H to ensure that the surface of the hollow half-shaft blank has a lubricating film layer with a thickness of 20 to 80μm; S5: placing the hollow half-shaft blank into the first diameter reduction die for the first diameter reduction; S6: placing the hollow semi-axle blank after the first diameter reduction into the second diameter reduction die for the second diameter reduction; S7: stress relief tempering of hollow half-shaft blank; S8: Finish turning the portion of the hollow half-shaft blank where the internal spline is to be extruded to a preset required size; S9: After the hollow half-shaft blank is fully preheated, it is hoisted into the second lubricant pool and soaked for 5S to 10S; the hollow half-shaft blank is hoisted to air-dry for 10Min, and then naturally dried for 24H to ensure that the surface of the hollow half-shaft blank has a lubricating film layer with a thickness of 20 to 80μm; S10: placing the hollow half-shaft blank into a cold extrusion spline device to extrude internal splines; S11: The outer diameter of the hollow half-shaft blank is precision-turned to the preset required size, and the hobbing position size on the hollow half-shaft blank is processed to the center line of the spline major diameter size; S12: center hole of double-top hollow half-shaft blank, gear hobbing spline; S13: quenching the surface of the hollow semi-axle blank by medium frequency heating, the medium frequency quenching frequency is 6KHZ to 10KHZ, the current is 82A, and the workpiece speed is 30r / min; S14: Grind the outer diameter of the bearing seat on the hollow half-shaft blank to the preset required size.

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