An integral axle head forming die for a drive axle housing with an axle head and a forming method thereof

Abstract

The present invention discloses a shaft head forming die and a forming method for an integral drive axle housing with a shaft head; it includes: a mandrel assembly, a die, and a clamping die; the clamping die is used to fix the axle housing; the die is provided in two groups; the two groups of the die cooperate with the mandrel assembly to upset and thicken the shaft head parts at both ends of the axle housing after hydro-pneumatic forming; the manufacturing method includes the following steps: Step 1) Locally heat the shaft head part at the end of the axle housing to an appropriate temperature and locally upset and thicken it through the die; Step 2) Reheat the shaft head at the end of the axle housing locally to an appropriate temperature and reduce the diameter of the shaft head part of the axle housing and form a shaft shoulder through spinning; the present invention solves the problems of local thickening of the shaft head part of the axle housing and instability and outward bulging of the axle housing during thickening when manufacturing the shaft head of the drive axle housing, and can accurately form the inner fillet size of the shaft head. The shaft head diameter reduction and the shaft shoulder forming are carried out on the same spinning machine, with high production efficiency and low cost.

Description

Technical Field

[0001] The present invention relates to the field of bridge housing manufacturing, and particularly to a shaft head forming die and a forming method for an integral drive bridge housing with shaft heads. Background Art

[0002] Axles with shaft heads are commonly found in load-bearing axles and expanding forming drive axles. Since the original tube diameter is small and the selected tube material can reach the hardness requirements of the shaft head after heat treatment, the shaft head can be manufactured by upsetting. During upsetting, no instability phenomenon will occur because the diameter difference between the shaft head and the original tube diameter is small. For the drive bridge housing formed by hydroforming, due to the relatively large equivalent diameter in the middle of the bridge housing, the wall thickness in the middle is relatively thin to meet the lightweight requirement, the diameter of the shaft head part is small, and the wall thickness is relatively thick to ensure the strength requirement. For such a drive bridge housing with an integral shaft head, first, to meet the requirements of hydroforming, a relatively large diameter original tube blank needs to be selected, and the tube material should have a large elongation rate. However, tubes with a large elongation rate cannot obtain a shaft head that meets the hardness requirements of the surface of the shaft head part through heat treatment. Second, the diameter of the shaft head is small, and the difference from the original tube diameter is relatively large, so instability is likely to occur in the transition area between the large diameter and the small diameter of the drive axle when forming the shaft head. Third, the inner wall fillet size in the transition area between the shaft head and the drive bridge housing body needs to be precisely controlled to ensure no stress concentration occurs;

[0003] Patent Publication No. CN111558665B discloses "a hydraulic bulging drive axle housing shaft head forming process and die". Its process requires four times of shaft end necking and three times of shaft end warm push pressing. The process steps are many and the production efficiency is low. Instability is likely to occur during necking and warm push pressing. The inner fillet of the bridge housing shaft head cannot be precisely controlled, and it is easy to produce a relatively small fillet or even crack. Seven sets of dies are required, and the cost is high. The selected tube material has a low elongation rate, which is not conducive to hydroforming; The present invention avoids instability and outward bulging when manufacturing the shaft head, and can ensure the inner fillet size of the shaft head to avoid the problem of stress concentration caused by the formation of relatively small fillets and cracks. The process steps are few and the production efficiency is high. Summary of the Invention

[0004] The technical solution adopted by the present invention is: a shaft head forming die for an integral drive bridge housing with shaft heads, including: a mandrel assembly, a die, and a clamping die; the clamping die is used to fix the bridge housing; the die is provided in two groups; the two groups of the die cooperate with the mandrel assembly to upset and thicken the shaft head parts at both ends of the hydroformed bridge housing.

[0005] Further, the mandrel assembly includes: a support ring; the support ring is composed of two semi-circular rings, and a connecting rod is fixedly installed on each semi-circular ring; a support shaft I and a support shaft II are fixedly installed between the semi-circular ring and the connecting rod in sequence, and each support shaft I is located on the side close to the support ring; all the support shafts I, support shafts II and connecting rods are coaxial; one end diameter of the support shaft II gradually increases step by step in the direction towards the support shaft I.

[0006] Further, each set of the molds includes: a base, and a protective ring is slidably installed on the base; the protective ring is sleeved outside the two shaft heads of the bridge shell after hydro-bulge forming; each base is in sliding fit contact with the corresponding connecting rod.

[0007] Further, the mold further includes: a screw; the screw rod of the screw passes through the protective ring and is threadedly connected to the base; the base and the protective ring are also elastically connected by a spring.

[0008] Further, the clamping mold includes: an upper clamping mold and a lower clamping mold; the lower clamping mold is placed on the hydraulic press platform and is used for placing the bridge shell after hydro-bulge forming; the upper clamping mold is fixedly connected to the upper slider of the hydraulic press; the upper clamping mold and the lower clamping mold cooperate with each other to fix the bridge shell after hydro-bulge forming through the hydraulic press.

[0009] A method for forming the shaft head of an integral drive axle housing with shaft heads, the overall process route is local thickening of the shaft head - spinning and reducing the diameter of the shaft head and forming the shaft shoulder, and the manufacturing method of the bridge shell shaft head includes the following steps:

[0010] Step 1) Forming of the locally thickened bridge shell:

[0011] Install the mandrel assembly into the bridge shell after hydro-bulge forming, heat the part of the end shaft head of the bridge shell after hydro-bulge forming that needs to be thickened to an appropriate temperature, and locally upset and extrude the end shaft head of the bridge shell after hydro-bulge forming through the mold, so as to obtain a locally thickened bridge shell with an unchanged outer diameter and a reduced inner diameter at the end shaft head.

[0012] Step 2) Forming of the stepped shaft head:

[0013] Heat the local part of the end shaft head of the locally thickened bridge shell to an appropriate temperature, reduce the diameter of the shaft head part of the locally thickened bridge shell by spinning with a reducing roller to obtain an end-reduced bridge shell, and obtain a stepped shaft head by spinning with a forming shaft shoulder roller.

[0014] Further: the bridge shell after liquid expansion and pressure forming in step 1) is a bridge shell that has been formed by liquid expansion and pressure forming, the cross-section of the middle and the plate support position has reached the required size, the reinforcing ring lute hole has been cut out in the middle, the cross-section of the bridge shell plate support position after liquid expansion and pressure forming is a rectangular tube, and the end cross-section is a circular ring, the mandrel assembly is composed of a support ring, a support shaft I, a support shaft II and a connecting rod, the support ring is composed of two semicircular rings, and the gap between the outer wall of the support ring and the inner wall of the middle part of the bridge shell after liquid expansion and pressure forming is 0.5 ~1mm, the gap between the large diameter outer circular wall of support shaft II and the inner wall of the circular end of the bridge housing after liquid expansion and pressure molding is 0.3~0.5mm, the outer diameter of the outer end of support shaft II is 20~22mm smaller than the inner diameter of the bridge housing tube end after liquid expansion and pressure molding, the support ring and support shaft I and support shaft II are connected together by connecting rods and nuts, the inner diameter of the guard ring in the mold is 0.2~0.4mm larger than the outer diameter of the end of the bridge housing after liquid expansion and pressure molding, the guard ring can slide in the base and be reset by a spring and limited by a screw.

[0015] Further: the step 1) is performed by upsetting and thickening on a three-way hydraulic press, the lower clamping die is fixed on the press workbench, the upper clamping die is fixed on the press main slide and moves up and down with the hydraulic press main slide, the hydraulic press slide moves downward to drive the upper clamping die to press the hydraulic press formed bridge shell, the left and right bases are respectively fixed on the press horizontal sliding template, the press horizontal sliding template drives the left and right bases and the guard ring to move toward the center, the guard ring first reaches the part of the bridge shell to be thickened after the liquid expansion and pressing, the end of the connecting rod is inserted into the smaller inner hole of the base to play a positioning and guiding role, the base performs upsetting and thickening on the end of the bridge shell after the liquid expansion and pressing, the inner hole wall of the guard ring prevents the end of the bridge shell after the liquid expansion and pressing from bulging outward during upsetting and thickening, the outer wall of the end of the support shaft II limits the thickening amount of the end of the bridge shell after the liquid expansion and pressing, and the support ring supports the inner wall of the middle part of the bridge shell after the liquid expansion and pressing to prevent local instability.

[0016] Furthermore: in the steps 1) and 2), the radius of the fillets Ra and Rb of the large diameter end of the support shaft II is 18mm~22mm, the reducing wheel is a discus-shaped wheel, the radius of the fillet Rc of the discus edge is 10mm~15mm, the shoulder wheel is a cylindrical wheel, and the fillet Rd between the cylindrical surface and the bottom surface is 4mm~6mm.

[0017] Further: When performing rotary swaging for reducing diameter and forming the shoulder in step 2), one end of the locally thickened axle housing loaded into the mandrel assembly is placed into the main shaft hole of the rotary swaging machine, clamped, and rotated by the main shaft. The rotary swaging machine drives the diameter-reducing rotary roller and the shoulder rotary roller to move axially from the head end side of the locally thickened axle housing to the other side. The diameter-reducing rotary roller is in the front and the shoulder rotary roller is in the rear. When the diameter-reducing rotary roller performs rotary swaging to reduce the diameter of the head end of the locally thickened axle housing, the rotary swaging machine drives the shoulder rotary roller to move radially so that it contacts the locally thickened axle housing to balance the force generated by the diameter-reducing rotary roller. When the shoulder rotary roller performs rotary swaging to form the shoulder of the locally thickened axle housing, the rotary swaging machine drives the diameter-reducing rotary roller to move radially so that it remains in contact with the locally thickened axle housing to balance the force generated by the shoulder rotary roller. The fillets Ra and Rb at the end of the support shaft II control the forming dimensions of the fillets Rf and Re on the inner wall of the stepped head.

[0018] The beneficial effects of the present invention are as follows: For the axle head of the hydro-pneumatic drive axle housing manufactured by the present invention, when forming the axle head, the wall thickness of the thickened axle head is increased without instability, and the fillet dimensions on the inner wall of the transition zone between the axle head and the drive axle body are accurately guaranteed, thereby avoiding stress concentration. Description of the Drawings

[0019] Figure 1 It is a schematic diagram of the tube blank after hydro-pneumatic forming in step 1) of the present invention.

[0020] Figure 2 It is a schematic diagram of upsetting and extruding the drive axle housing axle head in step 1) of the present invention.

[0021] Figure 3 For the present invention Figure 2 The enlarged schematic diagram of the structure at A.

[0022] Figure 4 It is a schematic sectional view of the overall structure of the present invention.

[0023] Figure 5 It is a schematic diagram of the mandrel assembly in step 1) of the present invention.

[0024] Figure 6 It is a schematic diagram of rotary swaging for reducing the diameter of the drive axle housing axle head in step 2) of the present invention.

[0025] Figure 7 It is a schematic diagram of rotary swaging for forming the shoulder in step 2) of the present invention.

[0026] Figure 8 It is a schematic diagram of the diameter-reducing rotary roller in step 2) of the present invention.

[0027] Figure 9 It is a schematic diagram of the shoulder rotary roller in step 2) of the present invention.

[0028] Figure 10 It is a schematic diagram after the axle head is formed in step 2) of the present invention.

[0029] Reference numerals: 1. axle housing after hydroforming; 2. axle housing with local thickening; 3. axle housing with end diameter reduction; 4. stepped axle head; 5. mandrel assembly; 5-1. support ring; 5-2. support shaft I; 5-3. support shaft II; 5-4. connecting rod; 6. die; 6-1. base; 6-2. return spring; 6-3. limit screw; 6-4. retaining ring; 7. diameter reduction roller; 8. shoulder roller; 9. clamping die; 91. upper clamping die; 92. lower clamping die. Detailed implementation mode

[0030] Example, as Figure 1-8 shown, a method for forming the axle head of an integral axle housing with an axle head drive, the overall process route is local thickening of the axle head - spinning and diameter reduction of the axle head and forming the shoulder, and the manufacturing method of the axle housing axle head includes the following steps:

[0031] Step 1) Forming the axle housing 2 with local thickening:

[0032] After the hydraulic expansion forming, the outer diameter ɸD1 of the end of the bridge housing 1 is ɸ160mm, and the wall thickness t1 is 14mm. The bridge housing 1 after the hydraulic expansion forming is installed into the core shaft assembly 5 to form an assembly. The specific installation is as follows: first, the half support ring 5-1 is installed from the lute hole of the bridge housing 1 after the hydraulic expansion forming into the middle part of the bridge housing 1 after the hydraulic expansion forming to form a complete ring, and the hole on the support ring 5-1 is roughly coaxial with the bridge housing 1 after the hydraulic expansion forming. The support shaft I and the support shaft II are penetrated by the connecting rod 5-4 and then inserted from the end of the bridge housing 1 after the hydraulic expansion forming, so that the threaded end of the connecting rod is inserted The support ring 5-1 is locked with a nut. The inner diameter of the guard ring 6-4 in the mold 6 is ɸ160.3mm. The guard ring 6-4 can slide in the base 6-1. The upsetting and thickening is carried out on a three-way hydraulic press. The lower clamping die 92 of the clamping die 9 is fixed on the workbench of the hydraulic press, and the upper clamping die 91 is fixed on the main slide of the hydraulic press. The left and right bases 6-1 are respectively fixed on the horizontal slides of the hydraulic press. The bridge housing 1 assembly after liquid expansion and pressing is placed in the lower clamping die, and the part of the end shaft head of the bridge housing 1 to be thickened after liquid expansion and pressing is heated to 900℃ by a medium frequency annealing device. ~1000℃, the main slider of the hydraulic press moves down to drive the upper clamping die 91 to press the bridge housing 1 after liquid expansion and pressure forming, and the horizontal slider of the hydraulic press drives the base 6-1 and the guard ring 6-4 to move synchronously toward the center. During this process, the end of the connecting rod 5-4 in the mandrel assembly 5 is inserted into the hole of the base 6-1 for guidance, and the guard ring 6-4 first reaches the part to be thickened, and the left and right bases 6-1 upset the end shaft head of the bridge housing 1 after liquid expansion and pressure forming. During upsetting, the inner hole wall of the guard ring 6-4 contacts and rubs with the outer wall of the end of the bridge housing 1 after liquid expansion and pressure forming and no longer moves, so as to prevent the bridge housing 1 after liquid expansion and pressure forming from being damaged. The end of the shell 1 bulges outward, and the outer wall of the end of the support shaft II 5-3 limits the thickening amount of the end of the bridge shell 1 after liquid expansion and pressure forming. The support ring 5-1 supports the inner wall of the middle part of the bridge shell 1 after liquid expansion and pressure forming to prevent local instability. At the end of upsetting, the horizontal slider of the hydraulic press drives the left and right bases 6-1 to move outward at the same time. The base 6-1 drives the guard ring 6-4 to move outward and away from the bridge shell 1 after liquid expansion and pressure forming through the screw 6-3. The main slider of the hydraulic press drives the upper clamping die 91 to move upward, and finally a locally thickened bridge shell 2 with an unchanged outer diameter of the end shaft head and a reduced inner diameter is obtained. The core shaft assembly 5 is not disassembled, and step 2 is executed);

[0033] Step 2) Forming of the stepped shaft head 4:

[0034] The reduction of the diameter of the end shaft head and the forming of the shoulder of the locally thickened axle housing 2 are carried out on a spinning machine. The radii of the fillets Ra and Rb at the large-diameter end of the support shaft II 5-3 are 20 mm. The fillet radius Rc of the reducing roller 7 is 12 mm, and the fillet radius Rd of the shoulder roller 8 is 5 mm. One end of the assembly of the locally thickened axle housing 2 is placed in the main shaft hole of the spinning machine and clamped. The end shaft head part of the locally thickened axle housing 2 is heated to 950 °C - 1050 °C by intermediate-frequency annealing. The main shaft of the spinning machine drives the locally thickened axle housing 2 to rotate. The spinning machine drives the reducing roller 7 and the shoulder roller 8 to move axially from one side of the end shaft head of the locally thickened axle housing 2 to the other side. The reducing roller 7 is in the front and the shoulder roller 8 is in the back, with a spacing of 30 mm. When the reducing roller 7 spins and reduces the diameter of the end of the locally thickened axle housing 2, the spinning machine drives the shoulder roller 8 to move radially to make it contact with the locally thickened axle housing 2 to balance the force generated by the reducing roller 7. When the shoulder roller 8 spins and forms the shoulder of the locally thickened axle housing 2, the spinning machine drives the reducing roller 7 to move radially to keep it in contact with the locally thickened axle housing 2 to balance the force generated by the shoulder roller 8. The fillets at the end of the support shaft II 5-3 control the forming size of the inner fillets at the end of the locally thickened axle housing 2. The diameter of the end shaft head part of the tube blank is reduced by spinning with the reducing roller 7 to obtain the end-reduced axle housing 3. The stepped shaft head 4 is obtained by spinning with the forming shoulder roller 8. Its main dimensions are that the outer diameter ɸD2 of the shaft head is ɸ98 mm, the wall thickness t2 is 20 mm, the fillet of the shoulder Re is R5 mm, the inner fillet of the shaft head Rf is R20 mm, and Rg is R20 mm. Heat is supplemented with a gas torch during the spinning process as required.

[0035] The process of the present invention is simple and efficient. During upsetting and extrusion thickening, it can effectively prevent the tube blank from losing stability and bulging outwards. When spinning and reducing the diameter and forming the shoulder, it ensures the precise size of the inner fillet of the shaft head, and manufactures the shaft head of the integral drive axle housing.

[0036] The above-mentioned embodiments are not restrictive embodiments of the present invention. Any modification or equivalent deformation made by those skilled in the art on the basis of the substantial content of the present invention is within the technical scope required to be protected by the present invention.

Claims

1. A method for forming a hub of an integral axle housing with a hub head, the overall process route being local thickening of the hub - spin - reducing the hub and forming a shoulder, characterized in that: The forming method of the axle head of the axle housing comprises the following steps: Step 1) Forming of the locally thickened axle housing (2): Install the mandrel assembly (5) into the axle housing (1) after hydro-bulging forming. Heat the part of the end axle head of the axle housing (1) after hydro-bulging forming that needs to be thickened to an appropriate temperature, and upset and extrude the local part of the end axle head of the axle housing (1) after hydro-bulging forming through the die (6), so as to obtain the locally thickened axle housing (2) with an unchanged outer diameter and a reduced inner diameter at the end axle head; Step 2) Forming of the stepped axle head (4): Heat the local part of the end axle head of the locally thickened axle housing (2) to an appropriate temperature, reduce the diameter of the axle head part of the locally thickened axle housing (2) by spinning through the reducing roller (7) to obtain the end-reduced axle housing (3), and obtain the stepped axle head (4) by spinning through the forming shoulder roller (8); The axle housing (1) after hydro-bulging forming in the said Step 1) is the axle housing that has been formed by hydro-bulging. The cross-sections at its middle part and the plate support position have reached the required dimensions. Reinforcing ring pipa holes have been cut out at the middle part. The cross-section of the plate support part of the axle housing (1) after hydro-bulging forming is a rectangular tube, and the end cross-section is an annular shape. The said mandrel assembly (5) is composed of a support ring (5-1), a support shaft I (5-2), a support shaft II (5-3) and a connecting rod (5-4). The support ring (5-1) is composed of two semi-circular rings. The gap between the outer wall of the support ring (5-1) and the inner wall of the middle part of the axle housing (1) after hydro-bulging forming is 0.5 - 1 mm. The gap between the outer wall of the large diameter of the support shaft II (5-3) and the inner wall of the round end of the axle housing (1) after hydro-bulging forming is 0.3 - 0.5 mm. The outer diameter of the outer end of the support shaft II is 20 - 22 mm smaller than the inner diameter of the tube end of the axle housing (1) after hydro-bulging forming. The support ring (5-1), the support shaft I (5-2) and the support shaft II (5-3) are connected together through the connecting rod (5-4) and nuts. The inner diameter of the protective ring (6-4) in the said die (6) is 0.2 - 0.4 mm larger than the outer diameter of the end of the axle housing (1) after hydro-bulging forming. The protective ring (6-4) slides in the base (6-1), and is reset by the spring (6-2) and limited by the screw (6-3); The base (6-1) upsets and thickens the two end axle head parts of the axle housing (1) after hydro-bulging forming.

2. A method for forming a hub of an integral axle housing with a hub head drive axle housing according to claim 1, characterized in that: In step 1), the upsetting and thickening is performed on a three-way hydraulic press. The lower clamping die (92) is fixed on the press workbench, and the upper clamping die (91) is fixed on the press main slide and moves up and down with the hydraulic press main slide. The bridge housing (1) after liquid expansion and pressing and loaded into the mandrel assembly (5) is placed in the lower clamping die (92). The hydraulic press slide moves downward to drive the upper clamping die (91) to press the bridge housing (1) after liquid expansion and pressing. The left and right bases (6-1) are respectively fixed on the press horizontal sliding template. The press horizontal sliding template drives the left and right bases (6-1) and the guard ring (6-4) to move toward the center. The center moves, the guard ring (6-4) first reaches the part of the bridge shell (1) to be thickened after liquid expansion and pressure forming, the end of the connecting rod (5-4) is inserted into the inner hole of the base (6-1) to play a positioning and guiding role, the base (6-1) performs upsetting and thickening on the end of the bridge shell (1) after liquid expansion and pressure forming, the inner hole wall of the guard ring (6-4) prevents the end of the bridge shell (1) after liquid expansion and pressure forming from bulging outward during upsetting and thickening, the outer wall of the end of the support shaft II (5-3) limits the thickening amount of the end of the bridge shell (1) after liquid expansion and pressure forming, and the support ring (5-1) supports the inner wall of the middle part of the bridge shell (1) after liquid expansion and pressure forming to prevent local instability.

3. The shaft head forming method of an integral drive axle housing with a shaft head according to claim 1, characterized in that: In the steps 1) and 2), the radius of the fillets Ra and Rb of the large diameter end of the support shaft II (5-3) is 18 mm to 22 mm, the reducing wheel (7) is discus-shaped, the radius of the fillet Rc of the disc edge is 10 mm to 15 mm, and the shoulder wheel (8) is cylindrical, and the fillet Rd between the cylindrical surface and the bottom surface is 4 mm to 6 mm.

4. A method for forming a hub of an integral axle housing with a hub head according to claim 1, characterized in that: In the step 2) of spinning to reduce the diameter and form the shoulder, one end of the partially thickened bridge housing (2) loaded into the mandrel assembly (5) is placed in the spindle hole of the spinning machine, clamped and driven to rotate by the spindle, and the spinning machine drives the reducing wheel (7) and the shoulder wheel (8) to move axially from the end of the shaft head of the partially thickened bridge housing (2) to the other side, with the reducing wheel (7) in front and the shoulder wheel (8) in the back. When the reducing wheel (7) spins the end of the partially thickened bridge housing (2) to reduce the diameter, the spinning machine drives the reducing wheel (7) to rotate the end of the partially thickened bridge housing (2). The movable shoulder wheel (8) moves radially to make it contact with the locally thickened bridge housing (2) to balance the force generated by the reducing wheel (7); when the shoulder wheel (8) spins the shoulder of the locally thickened bridge housing (2), the spinning machine drives the reducing wheel (7) to move radially to keep it in contact with the locally thickened bridge housing (2) to balance the force generated by the shoulder wheel (8), and the end radius Ra and Rb of the support shaft II (5-3) controls the forming dimensions of the inner wall radius Rf and Re of the stepped shaft head (4).

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