Heavy truck axle housing with integral axle head and body and method of manufacturing

Abstract

The axle head and the body of the heavy truck axle housing are integrally formed, the axle housing is composed of an axle cover, a rectangular straight pipe, a cylindrical straight pipe and an integral axle head, is integrally formed by a seamless steel pipe and has no welding seam, first, the middle part of the steel pipe is hot upset thickened to obtain a variable wall thickness pipe blank, the two sides are first hot extruded to realize the reducing of the rectangular straight pipe and the cylindrical straight pipe, and the end part is second hot extruded to form an axle head pipe blank; then, the upset thickened part of the pipe blank is hydraulically expanded to obtain a single drum pipe blank, the heavy truck axle housing pipe is obtained by multi-directional pressing after the inner cavity is filled with liquid, and the heavy truck axle housing is obtained by cutting an additional front cover and machining the axle head pipe blank. The application completely eliminates the defects existing in the split forming and welding of the body and the axle head of the heavy truck axle housing, has high strength, rigidity and fatigue life, the wall thickness of each part of the product is designed according to the bearing, the bending resistance is close to the equal strength, the weight is light, the manufacturing process is less, the efficiency is high, and the application is suitable for batch production.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of automobile manufacturing, and particularly relates to a heavy truck axle housing with an axle head and a body integrally formed and a manufacturing method thereof. BACKGROUND

[0002] The axle housing of the automobile drive axle is one of the main load-bearing components on the automobile, has a relatively complex geometric shape, is an assembly base of the main reducer, the differential, and the half shaft, mainly functions to support the automobile weight, bear the road surface reaction force and reaction torque transmitted by the wheels, and transmit the suspension to the vehicle frame or vehicle body. The performance directly affects the safety and reliability of the transport vehicle, should have sufficient strength and rigidity, and requires that the mass be reduced as much as possible to improve the smoothness of the automobile driving. The axle housing is an important load-bearing and force-transmitting component on the rear-drive vehicle, generally consists of an axle housing body (including a middle axle cover, two rectangular axle pipes, and a cylindrical straight pipe) and an axle head (also called a half shaft sleeve pipe). The axle head mainly supports the hub rotation while bearing the dynamic vertical load and bending moment, and requires higher fatigue strength relative to the axle housing body. Traditionally, the axle head is formed by die forging, upsetting, hot extrusion, or roll forging, and then is welded with the axle housing body to be integrated.

[0003] The heavy truck axle housing has large load bearing, complex shape, and large size, the maximum cross-sectional height of the axle cover can reach 560 mm, and the ratio of the axle cover to the diameter of the cylindrical straight pipe at both ends can be up to 4, which is difficult to manufacture.

[0004] The heavy truck axle housing body is mainly manufactured by stamping and welding, and is composed of an upper axle housing sheet body, a lower axle housing sheet body, four triangular gaskets, a rear cover, and a reinforcing ring (see FIG. 1), wherein the upper and lower axle housing sheet bodies are formed by stamping using steel plates with equal wall thickness, and the rear cover is formed by stamping using a steel plate with a thickness thinner than that of the upper and lower axle housing sheet bodies. The heavy truck axle housing manufactured by the stamping and welding method has long welds, and the welds at the rear cover and the triangular gaskets are prone to oil leakage. Meanwhile, the wall thickness of the connection between the rear cover and the upper and lower axle housing sheet bodies is thin, the rigidity is low, welding stress exists, the load capacity is weak, and the rear cover is prone to failure under heavy load. Figure 1

[0005] ​In recent years, the steel tube bulging forming process has emerged, which uses seamless steel tube to integrally form the axle housing body containing the rear cover, can greatly improve the strength and stiffness and fatigue life of the axle housing body, and is gradually entering the axle housing market. The overall forming method of a heavy truck axle housing without welding seam disclosed in Chinese patent (CN103252404A) selects a seamless steel pipe, performs push compression on both ends with a mandrel, performs hydraulic bulging on the middle part of the pipe blank, and then performs end diameter reduction to obtain a pre-bulging pipe blank in the shape of an approximate axisymmetric solid of revolution. After medium frequency annealing, the pipe blank is filled with liquid and pressed into an automobile axle housing pipe by using a mold. According to the method disclosed in Chinese patent (CN103252404A), the initial seamless steel pipe needs to be subjected to multi-pass large deformation cold push compression on both ends, and the wall thickness of both ends of the pipe blank after diameter reduction is increased by more than 50% compared with the middle part, which results in that the weight of the axle housing pipe after integral forming is large, limiting the lightweight of the product, and the strength of both sides of the axle pipe is relatively large, which is higher than the strength of the middle axle cover.

[0006] The punch-welded axle housing body needs to be welded with an axle head (half shaft sleeve), and the axle housing body manufactured by the bulging forming method (referred to as bulging forming axle housing or hydraulic bulging axle housing) still needs to be welded with an axle head. When the axle head is welded in a split manner, there are still hidden troubles such as virtual welding and incomplete welding, and an inner lining ring needs to be arranged. In the axle housing bench test and actual application, there is a phenomenon of welding seam cracking, which seriously affects the performance of the axle housing.

[0007] Chinese patent (CN111558665A) discloses a hydraulic bulging drive axle housing axle head forming process and mold. The hydraulic bulging axle housing (i.e. bulging forming axle housing) body is first manufactured, and then the axle pipes at both ends of the body are subjected to four times of cold diameter reduction and three times of warm push pressing of the axle end to form the axle head, and the mold structure for cold diameter reduction and warm push pressing of the axle end is disclosed. By using the process disclosed in Chinese patent (CN111558665A), an integral automobile axle housing is manufactured, the axle housing is realized without welding seam, and the fatigue strength of the axle housing is improved, but it is difficult to be used for mass production, mainly because: ①the wall thickness distribution of the axle head formed on the hydraulic bulging axle housing body is unreasonable, especially the wall thickness of the axle shoulder part which bears a large load is small, which is difficult to bear heavy load; ②the axle head diameter reduction forming process is multiple, which needs to be subjected to four times of cold diameter reduction, and when the single-pass diameter reduction deformation is large, the middle part of the already formed axle housing body may be deformed again and fail; the axle shoulder forming process is multiple, which needs to be subjected to three times of push pressing (i.e. pushing and extruding) forming; ③two times of heating annealing are performed during cold diameter reduction of the axle head, three times of heating are performed during push pressing of the axle shoulder, and in addition, heating is performed during the forming process of the axle housing body, the heating times are large, decarburization is serious, and the hardness of the axle head is seriously affected. SUMMARY

[0008] 1. Technical problem to be solved

[0009] The application provides a heavy truck axle housing with an integral axle head and body, the wall thickness of the middle axle housing, the two side rectangular straight pipes, the cylindrical straight pipe and the axle head at both ends is designed according to the bearing, the wall thickness distribution is reasonable, the bending resistance is close to the equal strength, the defects existing in the split forming and welding of the body and the axle head of the heavy truck axle housing are solved completely, the strength and rigidity of the axle housing are greatly improved, the fatigue life is greatly improved, the product is light in weight, the manufacturing process is less, the efficiency is high, and the product is suitable for mass production.

[0010] 2. Technical solution

[0011] The application provides a heavy truck axle housing (2) with an integral axle head and body, which is composed of a middle axle housing (2a), two side rectangular straight pipes (2b) of the axle housing, a cylindrical straight pipe (2c) outside the rectangular straight pipe, and an integral axle head (2d) at the outer end of the cylindrical straight pipe.

[0012] The axle housing (2a) is in the shape of a pipa, has a main reducer mounting hole (2f) on the front plane (2e) and a spherical crown-shaped integral rear cover (2g) on the rear side, the height of the maximum cross section in the middle is h1, the width of the upper and lower edge beams (2h) is b1, the wall thickness is t1, the height h1, the integral rear cover (2g), the distance from the crown top to the width center line of the upper and lower edge beams is b 11 , the wall thickness at the crown top is t 11 , t 11 =(0.90-0.95)t1; the integral rear cover (2g) and the rear plane (2i) of the axle housing are transitioned by a curved surface, the radius of the circular arc at the transition is R1, the wall thickness is t 12 , and t 12 =(0.95-1.0)t1, so that the rear cover side has high bending and torsional rigidity.

[0013] The height of the rectangular straight pipe (2b) is h2, the width is b2, and the wall thickness is t2, the width b2 is less than the width b1 of the upper and lower edge beams (2h) of the axle housing, and b2=(0.90-0.95)b1 is satisfied; the height h2 is greater than the width b2, and h2=(1.05-1.15)b2 is satisfied; the wall thickness t2 is greater than the wall thickness of the upper and lower edge beams (2h) of the axle housing (2a), and t2=(1.30-1.40)t1 is satisfied.

[0014] The cylindrical straight pipe (2c) has an outer diameter d1 and a wall thickness t3. The value of d1 is greater than the width b2 of the rectangular straight pipe (2b) and less than the height h2 of the rectangular straight pipe (2b); t3 is greater than the wall thickness t2 of the rectangular straight pipe (2b), and t3=(1.10-1.20)t2 is satisfied.

[0015] The integrated shaft head (2d) is a three-section stepped shaft tube. The first step (2j) on the inner side of the shaft head is used to install the brake flange, the second step (2k) in the middle of the shaft head, and the third step (2m) on the outer end of the shaft head are used to install tapered roller bearings, respectively. The first step (2j) of the shaft head transitions conically to the cylindrical straight tube (2c), with a semi-cone angle of θ1. The outer diameter of the first step (2j) of the shaft head is d2, satisfying d2 = (0.75~0.85)d1. There is a vertical shaft head shoulder (2n) between the second step (2k) of the shaft head and the first step (2j) of the shaft head. The outer diameter of the second step (2k) of the shaft head is d3, satisfying d3 = (0.75~0.85)d2. The wall thickness at the root of the shaft head shoulder (2n) is t4 = (1.15~1.25)t3. The outer diameter of the third step (2m) of the shaft head is d4, satisfying d4 = (0.85~0.95)d3. The wall thickness at the end is t5 = (0.55~0.65)t4. Moreover, the wall thickness of the inner cavity gradually increases from the outer end to the inner side.

[0016] This application provides a method for manufacturing a heavy-duty truck axle housing with the axle head and body integrally formed, and the process steps are as follows:

[0017] (1) Select a seamless steel pipe with an outer diameter d0 = (0.60~0.65)h1 and a wall thickness t1 based on the height h1 of the maximum cross section in the middle of the bridge bag (2a). The wall thickness t0 = (0.75~0.85)t1 and the length of the seamless steel pipe is L1.

[0018] (2) The seamless steel pipe is thickened by hot upsetting in the middle. The length L of the middle part of the pipe blank is increased. 10 The section is heated using three sets of medium-frequency furnaces with different frequencies, the middle length L 11 Partially heated to T1 = 950℃~1050℃, with length L on both sides. 12 L 13 Partially heated to T2 = 750℃~800℃; on a three-way hydraulic press, the heated tube blank is placed in the semi-cylindrical cavity of the upsetting and thickening lower die (3b), the upsetting and thickening upper die (3a) falls down, forming a closed cylindrical cavity with the upsetting and thickening lower die (3b), the inner diameter of the cavity being 2~3mm larger than the outer diameter d0 of the tube blank; the upsetting and thickening left die (3c) and the upsetting and thickening right die (3d) are pushed inward from both ends of the tube blank, with the middle length L 11 Part of the length becomes L 20 Wall thickness increase t 01 = (1.35~1.45)t0, the wall thickness on both sides is t 01 The linear length is reduced to t0. The length of the upset thickened tube blank (3) is reduced to L2.

[0019] (3) The upset thickened tube blank (3) is subjected to a first hot extrusion at both ends. After the upset thickened tube blank (3) is cooled to room temperature, the lengths L at both ends are... 21 L22 The part of the first extruded pipe blank (4) heated to T3=850-950℃; the middle part of the pipe blank is clamped by the first extrusion upper die (4a) and the first extrusion lower die (4b) and the left and right parts of the pipe blank are extruded by the first extrusion left die (4c) and the first extrusion right die (4d) to form the first stepped circular pipe (4e) and the second stepped circular pipe (4f). The outer diameter of the first stepped circular pipe (4e) is reduced to d 01 The wall thickness of the second stepped circular pipe (4f) reaches the wall thickness t2 of the rectangular straight pipe (2b) of the axle housing, i.e. t2=(1.35-1.45)t1; d 01 The outer diameter and the wall thickness of the second stepped circular pipe (4f) reach the outer diameter d1 and the wall thickness t3 of the cylindrical straight pipe (2c) of the axle housing, i.e. t3=(1.10-1.20)t2; the second stepped circular pipe (4f) is conically transitioned to the first stepped circular pipe (4e) with a half-cone angle θ2. The first heat extrusion is performed on a hydraulic machine and 2-3 working steps can be arranged. The length of the first extruded pipe blank (4) is increased to L3.

[0020] (4) The first extruded pipe blank (4) is subjected to the second heat extrusion to form the shaft head pipe blank. The second stepped circular pipe (4f) of the first extruded pipe blank (4) is heated to T4=850-950℃ at the length L 31 , L 32 The part of the first extruded pipe blank (4) heated to T3=850-950℃; the middle part of the pipe blank is clamped by the first extrusion upper die (4a) and the first extrusion lower die (4b) and the left and right parts of the pipe blank are extruded by the first extrusion left die (4c) and the first extrusion right die (4d) to form the first stepped circular pipe (4e) and the second stepped circular pipe (4f). The outer diameter of the first stepped circular pipe (4e) is reduced to d 21 The outer diameter of the first stepped circular pipe (4e) is reduced to d 31 The outer diameter of the first stepped circular pipe (4e) is reduced to d 41 The outer diameter of the first stepped circular pipe (4e) is reduced to d

[0021] (5) The second extruded pipe blank (5) is subjected to one hydraulic bulging. The middle part of the second extruded pipe blank (5) is heated to T5=850-950℃ at the length L 30The part of the diameter after the expansion becomes a single drum shape (6a), the outer diameter of the maximum cross section in the middle is d4, and the wall thickness is t5, satisfying d4=(0.92-0.95)h1 and t5=(1.02-1.06)t1; the length of the middle part is L 30 The parts of the two sides after the extrusion forming are not deformed. The length of the hydraulic bulging pipe blank (6) becomes L5.

[0022] (6) The middle part of the hydraulic bulging pipe blank (6) is subjected to the medium frequency annealing, the two ends are sealed, the inner cavity is filled with the low pressure liquid, and then the multi-directional pressing forming is carried out by using the upper and lower molds and the front and back molds, so as to obtain the heavy truck axle housing pipe fitting (7) with the integral forming of the axle head and the body. The first step (5e) of the axle head pipe blank, the second step (5f) of the axle head pipe blank and the cylindrical straight pipe (2c) are not deformed. The first step circular pipe (4e) becomes the rectangular straight pipe (2b) of the axle housing with the height h2 and the width b2. The single drum shape (6a) in the middle part becomes the axle housing (2a). The front flat surface (2e) is provided with the additional front cover (7a), and the rear flat surface (2i) is provided with the integral rear cover (2g). The distance between the crown top and the width center line of the upper and lower side beams is b 11 , and the wall thickness at the crown top is t 11 . The integral rear cover (2g) and the rear flat surface (2i) of the axle housing are transitioned by the curved surface, the radius R1 of the transition is the wall thickness t 12 . The height of the maximum cross section in the middle part of the axle housing (2a) is h1, the width of the upper and lower side beams (2h) is b1, and the wall thickness is t1. The length of the pressing formed axle housing pipe fitting (7) becomes L6.

[0023] (7) The additional front cover (7a) of the axle housing pipe fitting (7) is cut off, so as to obtain the main reducer mounting hole (2f).

[0024] (8) The first step (5e) of the axle head pipe blank is machined to obtain the first step (2j) of the axle head. The second step (5f) of the axle head pipe blank is machined to obtain the second step (2k), the third step (2m) of the axle head and the axle shoulder (2n).

[0025] The present application has the following advantages:

[0026] (1) The wall thickness of the middle part of the axle housing, the two side rectangular straight pipes, the cylindrical straight pipe and the two end axle heads of the integral forming of the axle head and the body is designed according to the bearing, the wall thickness distribution is reasonable, and the bending strength is close to the equal strength.

[0027] (2) The defects existing in the split forming and welding of the body and the axle head of the heavy truck axle housing are completely solved, and the strength and stiffness and the fatigue life of the axle housing are greatly improved.

[0028] (3) The product is light in weight, 10%-15% lighter than the punch-welding axle housing, and 5%-8% lighter than the axle housing manufactured by the bulging and pressing forming method. The manufacturing process is less and the efficiency is high, which is suitable for mass production. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 Front view of the stamping and welding axle housing of the heavy truck.

[0030] Figure 2 Front view of the stamping and welding axle housing of the heavy truck.

[0031] Figure 3 Front view of the stamping and welding axle housing of the heavy truck.

[0032] Figure 4 Front view of the stamping and welding axle housing of the heavy truck.

[0033] Figure 5 Front view of the stamping and welding axle housing of the heavy truck.

[0034] Figure 6 Temperature distribution diagram of the initial pipe blank in the middle part.

[0035] Figure 7 Schematic diagram of the upsetting and thickening process of the initial pipe blank in the middle part.

[0036] Figure 8 Upsetting and thickening pipe blank in the middle part of the initial pipe blank.

[0037] Figure 9 Schematic diagram of the first extrusion process.

[0038] Figure 10 First extrusion pipe blank.

[0039] Figure 11 Schematic diagram of the second extrusion process.

[0040] Figure 12 Second extrusion pipe blank.

[0041] Figure 13 Hydraulic bulging pipe blank.

[0042] Figure 14 Front view of the press-formed axle housing pipe.

[0043] Figure 15 Front view of the press-formed axle housing pipe.

[0044] In the above figures: 1. punch-welded bridge housing, 1a. split axle head, 1b. upper bridge housing piece, 1c. lower bridge housing piece, 1d. triangular gusset, 1e. rear cover, 1f. reinforcing ring, 1g. inner lining ring, 2. integrally formed heavy truck bridge housing, 2a. bridge package, 2b. rectangular straight pipe, 2c. cylindrical straight pipe, 2d. integral axle head, 2e. front flat surface, 2f. main reducer mounting hole, 2g. integral rear cover, 2h. side beam, 2j. axle head first step, 2k. axle head second step, 2m. axle head third step, 2n. axle head shoulder, 3. upset thick pipe blank, 3a. upset thick upper die, 3b. upset thick lower die, 3c. upset thick left die, 3d. upset thick right die, 4. first extruded pipe blank, 4a. first extruded upper die, 4b. first extruded lower die, 4c. first extruded left die, 4d. first extruded right die, 4e. first step round pipe, 4f. second step round pipe, 5. second extruded pipe blank, 5a. second extruded upper die, 5b. second extruded lower die, 5c. second extruded left die, 5d. second extruded right die, 5e. axle head pipe blank first step, 5f. axle head pipe blank second step, 5g. pipe blank shoulder, 6. hydraulic bulging pipe blank, 6a. single drum shape, 7. bridge housing pipe, 7a. additional front cover. DETAILED DESCRIPTION

[0045] Reference Figures 1-14 The present application provides a heavy truck bridge housing (2) with an integrally formed axle head and body, which is composed of a middle bridge package (2a), rectangular straight pipes (2b) on both sides of the bridge package, cylindrical straight pipes (2c) outside the rectangular straight pipes, and an integral axle head (2d) at the outer ends of the cylindrical straight pipes.

[0046] The bridge package (2a) is in the shape of a pipa, with a main reducer mounting hole (2f) on the front flat surface (2e) and a spherical cap-shaped integral rear cover (2g) on the rear side. The height of the largest cross section in the middle is h1=510mm, the width at the upper and lower side beams (2h) is b1=158mm, and the wall thickness is t1=9.8mm. The height h1 and the width b1 are determined according to the size of the main reducer's large gear, and t1 is determined according to the bending and torsional strength of the bridge package, and serves as the reference for the design of the wall thickness of other parts. The integral rear cover (2g) has a distance of b2=233mm from the width center line of the upper and lower side beams at the crown top, and a wall thickness of t3=9.0mm at the crown top, which satisfies t3=(0.90-0.95)t1. The integral rear cover (2g) and the rear flat surface (2i) of the bridge package are transitioned by a curved surface, with a circular arc radius R1=15mm at the transition and a wall thickness of t4=9.5mm, which satisfies t4=(0.95-1.0)t1, so that the side of the rear cover has high bending and torsional rigidity. 11 11 11 12 12

[0047] ​​​​​The height of the rectangular straight pipe (2b) is h2=158mm, the width is b2=145mm, the wall thickness is t2=13.2mm, the width b2 is less than the width b1 at the upper and lower edge beams (2h) of the bridge package, and satisfies b2=(0.90-0.95)b1; the height h2 is greater than the width b2, and satisfies h2=(1.05-1.15)b2; the wall thickness t2 is greater than the wall thickness at the upper and lower edge beams (2h) of the bridge package (2a), and satisfies t2=(1.30-1.40)t1.

[0048] The outer diameter of the cylindrical straight pipe (2c) is d1=φ150mm, the wall thickness is t3=15mm, t3 is greater than the wall thickness t2 of the rectangular straight pipe (2b), and satisfies t3=(1.10-1.20)t2.

[0049] The integral shaft head (2d) is a three-section stepped shaft pipe, the inner shaft head first step (2j) is used for installing the brake flange, the middle shaft head second step (2k) and the outer end shaft head third step (2m) are used for installing the tapered roller bearing respectively. The shaft head first step (2j) is tapered with the cylindrical straight pipe (2c), the half taper angle is θ1=60°, the outer diameter of the shaft head first step (2j) is d2=φ120mm, and satisfies d2=(0.75-0.85)d1; there is a vertical shaft shoulder (2n) between the shaft head second step (2k) and the shaft head first step (2j), the outer diameter of the shaft head second step (2k) is d3=φ95mm, and satisfies d3=(0.75-0.85)d2, the wall thickness t4=18mm at the root of the shaft head shoulder (2n), and satisfies t4=(1.15-1.25)t3; the outer diameter of the shaft head third step (2m) is d4=φ82.5mm, the wall thickness t5=11mm at the end, and satisfies t5=(0.55-0.65)t4, and the wall thickness of the inner cavity gradually increases from the outer end to the inner side.

[0050] The application provides a heavy truck axle housing manufacturing method with an integral shaft head and body, and the process steps are as follows:

[0051] (1) According to the height h1 of the maximum section in the middle of the bridge package (2a) and the wall thickness t1, a seamless steel pipe is selected, the outer diameter d0=φ325mm, the wall thickness t0=8mm, and satisfies d0=(0.60-0.65)h1, t0=(0.75-0.85)t1, and the length L1 of the seamless steel pipe is 2160mm.

[0052] (2) The middle part of the seamless steel pipe is thickened by hot upsetting. The part with a length L 10 =1000mm in the middle of the pipe blank is heated by three groups of medium-frequency heating with different frequencies, the part with a length L 11 =600mm in the middle is heated to T1=950-1050℃, the parts with lengths L 12 =200mm on the left and right sides are heated to T2=950-1050℃, and the part with a length L13 The portion of tube blank with a diameter of 200mm is heated to T2 = 750℃~800℃; on a three-way hydraulic press, the heated tube blank is placed on the semi-cylindrical cavity of the upsetting and thickening lower die (3b), and the upsetting and thickening upper die (3a) falls down, forming a closed cylindrical cavity with the upsetting and thickening lower die (3b). The inner diameter of the cavity is 2~3mm larger than the outer diameter d0 of the tube blank; the upsetting and thickening left die (3c) and the upsetting and thickening right die (3d) are pushed inward from both ends of the tube blank, with the middle length L 11 Part of the length becomes L 20 =460mm, wall thickness increased to t 01 =11.2mm, satisfying t 01 = (1.35~1.45)t0, the wall thickness on both sides is determined by t 01 The linear length is reduced to t0. The length of the upset thickened tube blank (3) is reduced to L2 = 1970 mm.

[0053] (3) The upset thickened tube blank (3) is subjected to a first hot extrusion at both ends. After the upset thickened tube blank (3) is cooled to room temperature, the lengths L at both ends are... 21 =580mm, L 22 The 660mm section is heated to T3 = 850℃~950℃; on a three-way hydraulic press, the middle of the tube blank is held by the first extrusion upper die (4a) and the first extrusion lower die (4b), and the diameter is reduced by the first extrusion left die (4c) and the first extrusion right die (4d), forming the first stepped round tube (4e) and the second stepped round tube (4f). The outer diameter of the first stepped round tube (4e) is reduced to d. 01 =φ179mm, wall thickness reaches the wall thickness t2 = 13.2mm of the rectangular straight tube (2b) of the bridge shell, that is, t2 = (1.30~1.40)t1; d 01 The outer diameter and wall thickness of the second-step circular tube (4f) are determined based on the perimeter of the rectangular straight tube (2b) of the bridge shell. The outer diameter d1 = φ150mm and wall thickness t3 = 15mm of the cylindrical straight tube (2c) of the bridge shell, respectively, i.e., t3 = (1.10~1.20)t2; the second-step circular tube (4f) and the first-step circular tube (4e) are conically transitioned, with a half-cone angle of θ2 = 20°. The first extrusion is carried out on a hydraulic press, and 2 to 3 steps can be arranged. The length of the tube blank (4) after the first extrusion is increased to L3 = 2195mm.

[0054] (4) The first extruded tube blank (4) is subjected to a second hot extrusion to form a shaft-end tube blank. The length L of the second stepped round tube (4f) of the first extruded tube blank (4) is taken from both ends. 31 =240mm, L 32= 240 mm is heated to T4 = 850-950℃, and the middle part of the pipe blank is clamped by the second extrusion upper die (5a), the second extrusion lower die (5b), the second extrusion left die (5c) and the second extrusion right die (5d) on a three-way hydraulic machine, and extrusion is performed to form the first step (5e) and the second step (5f) of the shaft head pipe blank; the first step (5e) of the shaft head pipe blank is tapered to the cylindrical straight pipe (2c) with a half-cone angle θ1 = 60°, and the second step (5f) of the shaft head pipe blank forms a shoulder (5g) with the first step (5e) of the shaft head pipe blank; the outer diameter d 21 of the first step (5e) of the shaft head pipe blank is φ124 mm, which is 4 mm larger than the outer diameter d2 of the first step (2j) of the shaft head; the outer diameter d 31 of the second step (5f) of the shaft head pipe blank is φ99 mm, which is 4 mm larger than the outer diameter d3 of the second step (2k) of the shaft head; the wall thickness t 41 at the root of the shoulder (5g) of the shaft head pipe blank is 20 mm, which is 2 mm larger than the wall thickness t4 at the root of the shoulder (2n) of the shaft head; the second extrusion forming is performed on another hydraulic machine, and 2-3 steps can be arranged; the length of the second extrusion pipe blank (5) is changed to L4 = 2150 mm.

[0055] (5) The second extrusion pipe blank (5) is subjected to one-time hydraulic bulging, and the middle part with a length L 30 = 460 mm is expanded in diameter to become a single drum (6a) with an outer diameter d4 = φ470 mm and a wall thickness t5 = 10 mm at the maximum cross section in the middle, which satisfies d4 = (0.92-0.95)h1 and t5 = (1.02-1.06)t1; the two sides of the pipe blank are not deformed. The length of the hydraulic bulging pipe blank (6) is changed to L5 = 1995 mm. 30

[0056] (6) The middle part of the hydraulic bulging pipe blank (6) is subjected to medium-frequency annealing, the two ends are sealed, the inner cavity is filled with liquid under low pressure, and multi-directional pressing is performed by using upper and lower dies and front and rear dies to obtain the heavy truck axle housing pipe fitting (7) with the shaft head and the body integrally formed; the first step (5e) and the second step (5f) of the shaft head pipe blank and the cylindrical straight pipe (2c) are not deformed, the first step circular pipe (4e) becomes the rectangular straight pipe (2b) of the axle housing, the single drum (6a) in the middle part becomes the axle housing (2a), the front flat surface (2e) is provided with an additional front cover (7a), and the rear flat surface (2i) is provided with an integral rear cover (2g); the distance between the crown top and the width center line of the upper and lower side beams is b 11 , and the wall thickness at the crown top is t 11 ; the integral rear cover (2g) and the rear flat surface (2i) of the axle housing are transitioned by a curved surface, and the radius R1 of the circular arc at the transition and the wall thickness t 12 ​The height of the maximum cross section in the middle of the bridge package (2a) is h1, the width of the upper and lower side beams (2h) is b1, and the wall thickness is t1. After pressing, the length of the bridge shell pipe (7) becomes L6=2000mm.

[0057] (7) Cut off the additional front cover (7a) of the bridge shell pipe (7) to obtain the main reducer mounting hole (2f).

[0058] (8) Machining the first step (5e) of the shaft head pipe blank to obtain the first step (2j) of the shaft head, machining the second step (5f) of the shaft head pipe blank to obtain the second step (2k) of the shaft head, the third step (2m) of the shaft head, and the shaft shoulder (2n).

Claims

1. A heavy truck axle housing manufacturing method of shaft head and body integrated forming, characterized in that: The heavy truck axle housing (2) of shaft head and body integrated forming is composed of axle housing (2a), rectangular straight pipe (2b) on both sides of axle housing, cylindrical straight pipe (2c) and integrated shaft head (2d). The axle housing (2a) is in the shape of a pipa, with an integrated rear cover (2g) on the rear side. The height of the largest cross section in the middle is h1, the width at the upper and lower beams (2h) is b1, and the wall thickness is t1. The height of the rectangular straight pipe (2b) is h2, the width is b2, and the wall thickness is t2, t2=(1.30-1.40)t1. The outer diameter of the cylindrical straight pipe (2c) is d1, and the wall thickness is t3, t3=(1.10-1.20)t2. The integrated shaft head (2d) is a three-step stepped shaft pipe. The wall thickness t4 at the root of the shaft shoulder (2n) is (1.15-1.25)t3, and the wall thickness t5 at the end is (0.55-0.65)t4. The wall thickness of the inner cavity gradually increases from the outer end to the inner side. The distance from the crown top to the width center line of the upper and lower side beams of the integrated rear cover (2g) is b 11 The wall thickness at the crown top is t 11 , and t 11 = (0.90-0.95) t1 is satisfied; the integrated rear cover (2g) and the bridge package rear plane (2i) are transitioned by a curved surface, the radius R1 of the arc at the transition is t 12 , the wall thickness is t 12 , and t 12 = (0.95-1.0) t1 is satisfied, so that the rear cover side has high bending and torsional rigidity; The integrated shaft head (2d) is a three-step stepped shaft pipe. The shaft head first step (2j) on the inner side is tapered with the cylindrical straight pipe (2c), with a half-cone angle of θ1. The outer diameter of the shaft head first step (2j) is d2, which satisfies d2=(0.75-0.85)d1. There is a vertical shaft shoulder (2n) between the shaft head second step (2k) in the middle and the shaft head first step (2j). The outer diameter of the shaft head second step (2k) is d3, which satisfies d3=(0.75-0.85)d2. The wall thickness t4 at the root of the shaft shoulder (2n) is (1.15-1.25)t3. The outer diameter of the shaft head third step (2m) at the end is d4, which satisfies d4=(0.85-0.95)d3. The wall thickness t5 at the end is (0.55-0.65)t4. Moreover, the wall thickness of the inner cavity gradually increases from the outer end to the inner side. The method comprises the following steps: 1) Select a seamless steel pipe according to the height h1 of the largest cross section in the middle of the axle housing (2a) and the wall thickness t1. The outer diameter d0=(0.60-0.65)h1, and the wall thickness t0=(0.75-0.85)t1. The length of the seamless steel pipe is L1. 2) The seamless steel pipe is thickened by hot upsetting in the middle, increasing the length L of the middle section of the billet. 10 The section is heated using three sets of medium-frequency furnaces with different frequencies, the middle length L 11 Partially heated to T1 = 950℃~1050℃, with length L on both sides. 12 L 13 Partially heated to T2 = 750℃~800℃; the heated tube blank is placed in the semi-cylindrical cavity of the upsetting and thickening lower die (3b) on a three-way hydraulic press, the upsetting and thickening upper die (3a) falls down, and the upsetting and thickening left die (3c) and upsetting and thickening right die (3d) are pushed inward from both ends of the tube blank, with the middle length L 11 Part of the length becomes L 20 Wall thickness increase t 01 =(1.35~1.45)t0, the wall thickness on both sides is determined by t 01 Linearly reduced to t0; 3) first hot extrusion, realizing the reducing of rectangular straight pipe and cylindrical straight pipe; upsetting thickening pipe blank (3) After cooling to room temperature, the left and right end length L 21 , L 22 part is heated to T3=850~950℃; on the three-way hydraulic machine, using the first extrusion upper die (4a), the first extrusion lower die (4b) to clamp the middle part of the pipe blank, using the first extrusion left die (4c), the first extrusion right die (4d) to extrude and reduce the diameter, forming the first step circular pipe (4e), the second step circular pipe (4f); the outer diameter of the first step circular pipe (4e) is reduced to d 01 , the wall thickness reaches the wall thickness t2 of the bridge housing rectangular straight pipe (2b); d 01 is determined according to the circumference of the bridge housing rectangular straight pipe (2b); the outer diameter and the wall thickness of the second step circular pipe (4f) respectively reach the outer diameter d1 and the wall thickness t3 of the bridge housing cylindrical straight pipe (2c); the second step circular pipe (4f) and the first step circular pipe (4e) are conical transition, and the half cone angle is θ2; 4) the second time hot extrusion forms the shaft head pipe blank; the length L of the second step circular pipe (4f) left and right ends of the first time extruded pipe blank (4) is heated to T4=850-950℃, the middle part of the pipe blank is clamped by the second time extrusion upper die (5a) and the second time extrusion lower die (5b) on the three-way hydraulic machine, the second time extrusion left die (5c) and the second time extrusion right die (5d) are extruded to form the shaft head pipe blank first step (5e) and the shaft head pipe blank second step (5f); the shaft head pipe blank first step (5e) is tapered with the cylindrical straight pipe (2c) with a half taper angle θ1, and the shaft head pipe blank second step (5f) forms the pipe blank shaft shoulder (5g) with the shaft head pipe blank first step (5e); 31 , 32 ​ 5) the second extruded tube blank (5) is subjected to one hydraulic bulging, the middle part of length L 30 is expanded in diameter and becomes a single drum (6a) with an outer diameter d4 and a wall thickness t5 at the maximum cross section, satisfying d4 = (0.92-0.95)h1 and t5 = (1.02-1.06)t1; the middle part of length L 30 is not deformed; 6) The middle of the hydraulic expansion pipe blank (6) is annealed in the middle frequency, both ends are sealed, and the inner cavity is filled with liquid. After that, the upper and lower molds and the front and rear molds are used for multi-directional pressing to form the heavy truck axle housing pipe fitting (7) of shaft head and body integrated forming. The shaft head pipe blank first step (5e), the shaft head pipe blank second step (5f) and the cylindrical straight pipe (2c) are not deformed. The first step circular pipe (4e) becomes the axle housing rectangular straight pipe (2b). The middle single drum (6a) becomes the axle housing (2a), the front plane (2e) has an additional front cover (7a), and the rear plane (2i) has an integrated rear cover (2g). 7) The additional front cover (7a) of the axle housing pipe fitting (7) is cut off to obtain the main reducer mounting hole (2f). 8) The shaft head first step (2j) is obtained by machining the shaft head pipe blank first step (5e), and the shaft head pipe blank second step (5f) is obtained by machining the shaft head second step (2k), the shaft head third step (2m) and the shaft shoulder (2n).

2. The method for manufacturing a heavy-duty truck axle housing with the axle head and body integrally formed as described in claim 1, characterized in that... When the middle part of the seamless steel pipe is thickened by hot upsetting, the upsetting thickening upper die (3a) and the upsetting thickening lower die (3b) form a closed cylindrical cavity, and the cavity inner diameter is 2-3mm larger than the pipe blank outer diameter d0.

3. The method for manufacturing a heavy-duty truck axle housing with the axle head and body integrally formed as described in claim 2, characterized in that... When the upsetting thickening pipe blank (3) is subjected to the first hot extrusion, 2-3 steps are arranged on a hydraulic press.

4. The method for manufacturing a heavy-duty truck axle housing with the axle head and body integrally formed as described in claim 3, characterized in that... When the first extruded tube blank (4) is subjected to a second hot extrusion forming, the outer diameter d of the first step (5e) of the shaft-end tube blank is... 21 The outer diameter d2 of the first step (2j) of the shaft head is 3-4 mm larger than that of the second step (5f) of the shaft head tube blank. 31 The outer diameter d3 of the second step (2k) of the tube blank is 3-4 mm larger than that of the second step (2k), and the wall thickness t at the root of the tube blank shoulder (5g) is also larger. 41 The wall thickness t4 at the root of the shaft head and shoulder (2n) is 1.5 to 2 mm greater than that of the shaft head and shoulder (2n); the second hot extrusion forming is carried out on another hydraulic press, with 2 to 3 steps.

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