A hollow commercial vehicle front axle and a method of manufacturing the same

Abstract

The application discloses a hollow commercial vehicle front axle and a manufacturing method thereof. The front axle is composed of an axle body and a steel plate spring seat. The axle body is a hollow structure obtained by reducing and upsetting an end portion of a seamless steel pipe, bending and pressing forming. The crossbeam and the bent neck of the axle body are thin-walled rectangular pipes with equal wall thickness and variable cross section. The fist part is a thick-walled rectangular cylinder with constant height and gradually narrowing width from the inside to the end portion. A strip-shaped hole is arranged on the outer end curved surface of the fist part and is welded and solidified by a welding plug. A concave limiting groove is arranged on the front side surface. The steel plate spring seat is composed of an upper cover and a lower support. The upper cover is clamped on the upper portion of the crossbeam, and the lower support is clamped on the middle portion of the crossbeam and covers the lower portion of the crossbeam. The hollow commercial vehicle front axle provided by the application can replace the existing forged, combined welded and punched and welded front axle, has light product weight, high bending and torsional strength, and is easy to match with the existing suspension system for vehicle mounting. The axle body has good forming quality, no defects such as folding and outer side cracks in the fist part inner cavity, and high shear performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of automobile parts, and particularly relates to a hollow commercial vehicle front axle and a manufacturing method thereof. BACKGROUND

[0002] The commercial vehicle front axle is one of important parts of a chassis. During vehicle driving, the front axle needs to bear loads generated due to uneven road surface, vehicle emergency braking and continuous turning, so the front axle is required to have high strength, rigidity and fatigue life. The front axle is generally composed of a cross beam, two side bends and a fist.

[0003] The vehicle front axle can be divided into an integral forging front axle, a steel pipe combined welding front axle and a steel plate stamping welding front axle according to manufacturing processes. The integral forging front axle is a mainstream commercial vehicle front axle manufacturing method on the market at present.

[0004] ATTACHMENT Figure 1 The integral forging front axle is formed integrally with a solid I-beam structure at a middle section of a cross beam and two side bends, and solid fist ends. The middle section of the cross beam is an I-shaped structure with approximately equal width of upper and lower parts, and the two sides of the cross beam are I-shaped with upper wide and lower narrow parts. The wide upper wing surface is directly used as a leaf spring seat, and forms a difference H0 with the middle section of the cross beam. The integral forging front axle manufacturing process is relatively mature, the leaf spring seat is integrally formed with the front axle to reduce welding influence, the material utilization rate reaches 80% to 85%, and the integral forging front axle has been widely applied to front axles with axle load of 3.5T to 7T. The forging front axle has large weight, the lower wing width of the cross beam two sides is narrow, the bending strength is not high, the I-shaped cross beam has low torsional strength, and the cross beam two sides are prone to failure under the condition of vehicle emergency braking. The forging forming process needs large forging equipment, the development cost of the die is high and it is not easy to change the type, and the flash is prone to appear in the forming process to reduce the service life of the front axle.

[0005] Figure 2 The steel pipe combined welding front axle has a circular pipe at the cross beam, the two side bends and the fist are integrally forged, and the leaf spring seat is welded at both sides of the middle section of the cross beam after the cross beam is welded with the integrally formed side bends. Compared with the forging front axle, the steel pipe combined welding front axle does not need large forging equipment, reduces the development cost of the die and the difficulty of changing the type, but the bending performance of the cross beam circular pipe is low, and the welding quality is required to be high at the cross beam ends and the leaf spring seat. At present, the steel pipe combined welding front axle is mainly applied to small front axles with axle load less than 3.5T, and is rarely used for large axle load front axles.

[0006] Figure 3The front axle is stamped and welded by upper plate, lower plate, front and rear side plates, and is welded at both ends. This structure is relatively simple, does not require large forging equipment, and has low mold development cost, but the manufacturing process is complex, there are many welding positions, some welds are long, the welding quality is high, the fatigue life is low, the impact resistance is poor, and it is mainly applied to engineering vehicles and special vehicles with axle load greater than 7T and low speed.

[0007] Chinese patent

CN102092236A

[0008] Chinese patent

CN113714743A

[0009] Chinese patent

CN115194419A

[0010] 1. Technical problem to be solved

[0011] The present application provides a variable cross-section and variable wall thickness hollow commercial vehicle front axle formed by seamless steel pipe, which can replace the existing forged front axle, combined welded front axle and punch-welded front axle to meet the existing suspension system installation conditions, completely solve the hidden dangers caused by the fist part body welding, eliminate the fatal defects such as folding and cracking existing in the overall forming of the fist part of the front axle, and greatly improve the bending and torsional resistance under the premise of reducing the weight of the product.

[0012] 2. Technical solution

[0013] In order to achieve the above purpose, the present application provides a hollow commercial vehicle front axle and a manufacturing method thereof. The hollow commercial vehicle front axle is composed of an axle body and a leaf spring seat. The axle body includes a beam (3), bent necks (2) on both sides of the beam, and a fist part (1) connected to the bent necks. The overall structure is a variable cross-section and variable wall thickness hollow rectangular section structure, which is formed by seamless steel pipe.

[0014] The crossbeam (3) is divided into a middle section (3a) and left and right sections (3b, 3c). The height h1, width b1 and wall thickness t1 of the middle section (3a) are determined according to the bending strength, and are used as the design reference for the geometric parameters of the rectangular cross section of the other sections. The left and right sections (3b, 3c) have the same rectangular cross section as the middle section (3a), with slightly increased height and slightly decreased width, to ensure high bending and torsion resistance. The height h2 of the left and right sections (3b, 3c) is h1+(5-15mm), and the width b2 is b1-(5-15mm). The cross section is raised upward, and the bottom is raised by H1=(5-15mm) compared with the middle section (3a), to meet the minimum ground clearance after installation of the steel plate spring.

[0015] The inner side of the bent neck (2) is connected to the crossbeam (3), and is bent upward to form a curved corner (2a) with an excessive corner radius R1. The angle between the axis of the bent neck (2) and the horizontal line is θ1. The wall thickness of the bent neck (2) is the same as that of the middle section (3a), the width is increased and the height is decreased to enhance the torsion resistance, with the width b3=b1+(5-20mm) and the height h3=h1-(5-20mm).

[0016] The outer side of the bent neck (2) is connected to the fist part (1), which is a thick-walled rectangular tube (1b) with constant height and gradually narrowing width from the inner side to the end. The fist part (1) is provided with a king pin hole (1a) for installing the king pin, with a hole diameter of φd1. The inner cavity of the thick-walled rectangular tube (1b) is composed of four upper and lower and front and rear concave surfaces, with a top corner between adjacent surfaces. The cross section passing through the axis of the king pin hole (1a) has a height h4=(0.80-0.90)h1, a width b4=(0.90-1.0)b1 and a wall thickness t4=(1.40-1.60)t1, to ensure sufficient bending and torsion resistance.

[0017] The outer end of the fist part (1) is composed of three curved surfaces, with a width direction middle section cylindrical curved surface (1c) having a curvature radius R2 and a central angle θ4, and front and rear side curved surfaces having a curvature radius R3. A strip hole (1d) is provided at the middle part of the height of the cylindrical curved surface (1c), with a height h5=(0.25-0.40)d1 and a width b5=(0.10-0.25)d1, to ensure high bending and shearing resistance of the fist part. The strip hole (1d) is welded with a plug (4).

[0018] The inner recessed rectangular limiting slot (1e) is arranged on the front side of the fist part (1) at the position deviated inward and downward from the king pin hole axis (1a), and is used to limit the rotation angle of the steering knuckle installed on the front axle; the lock pin hole (1f) is arranged at the position deviated upward from the king pin hole axis (1a), and the hole diameter is φd2, and the distance between the axis of the lock pin hole (1f) and the axis of the king pin hole (1a) is c1.

[0019] The steel plate spring seat of the hollow commercial vehicle front axle is composed of an upper cover (5) and a lower support (6), the upper cover (5) is in the shape of a bench and is composed of an upper plate (5a) and upper cover vertical walls (5b) on the front and back sides, the upper plate (5a) is the installation base of the steel plate spring, the height H2 of the upper surface of the upper plate (5a) and the height of the king pin hole (1a) of the fist part is the first level difference of the front axle, the axial width of the upper plate (5a) is c2, the front and back direction length is c3, and a cylindrical hole (5c) with a diameter of φd3 is arranged at the center; the upper cover vertical walls (5b) are clamped on the upper parts of the left section (3b) and the right section (3c) of the cross beam and are welded together. The lower support (6) is in the shape of a U-shaped structure with a triangle hollow, is composed of a base plate (6a), front and back base plate vertical walls (6b) above the base plate, and three rib plates (6c) below the base plate, a rib (6d) is arranged between the base plate (6a) and the base plate vertical walls (6b); the base plate vertical walls (6b) are clamped on the middle parts of the left section (3b) and the right section (3c) of the cross beam and are welded together. The three rib plates (6c) below the base plate cover the lower parts of the left section (3b) and the right section (3c) of the cross beam. Four horse bolt holes (6e) with a hole diameter of φd4 are symmetrically arranged on the base plate (6a), the left and right hole distance of the horse bolt holes (6e) is c4, the front and back hole distance is c5, and the installation conditions of the front axle and the suspension are ensured, that is, c5=b2+(45-55mm). The horse bolt of the suspension effectively assembles the cross beam (3), the upper cover (5) and the lower support (6) by using the steel plate spring seat, the stress state of the cross beam is good, the service life is long, and the lightweight is convenient.

[0020] The application also provides a manufacturing method of the hollow commercial vehicle front axle, a seamless steel pipe with an initial outer diameter D0 and a wall thickness t0 is selected, the hollow rectangular front axle pipe (8) is obtained by two-end diameter reduction-upsetting, bending and overall pressing forming, and finally machining, welding and other steps are performed, and the method is characterized in that:

[0021] (1) the end part of the seamless steel pipe is subjected to hot-state diameter reduction-upsetting, the end part of the pipe blank is subjected to hot-state diameter reduction-upsetting to obtain a diameter reduction-upsetting pipe blank (7), the end part diameter D1 is reduced to (0.85-0.95) times of the initial pipe blank outer diameter D0, the wall thickness t 01 is increased to (2.2-2.5) times of the initial wall thickness t0, and the wall thickness of the diameter reduction-upsetting part of the pipe blank and the inner side undeformed area gradually changes, and the inner cavity transition fillet radius R4 is not less than 20mm.

[0022] (2) The reduced diameter-upset tube blank (7) is bent and then integrally press formed into a hollow rectangular front axle pipe (8). The middle part of the reduced diameter-upset tube blank (7) is formed into a thin-walled rectangular cross-section beam (3) and two side bends (2), the wall thickness is basically unchanged, the height of the middle section (3a) of the beam becomes h1, the face width becomes b1, the height of the left section (3b) and the right section (3c) of the beam becomes h2, the face width becomes b2, and the height of the bend (2) becomes h3, the face width becomes b3.

[0023] The end part of the reduced diameter-upset tube blank (7) becomes a front axle pipe fist (8a) and an outer square end (8b). The front axle pipe fist (8a) is a thick-walled cylinder with a constant height and gradually narrowing width from the inside to the end. On the section of the front axle pipe fist (8a) where the kingpin hole is to be machined, the height h4=(0.80-0.90)h1, the width b4=(0.90-1.0)b1, and the wall thickness t5=(2.40-2.70)t1. The inner cavity is composed of an inner concave upper curved surface (8c), a lower curved surface (8d), a front curved surface (8e), and a rear curved surface (8f). There is a top corner (8g) between adjacent curved surfaces. The fillet radius R5 at the top corner (8g) is not less than 5mm, and folding and cracking defects are not allowed. The height h6=(0.45-0.60)h1 and the width b6=(0.55-0.70)b1 of the square end (8b). The outer side of the square end (8b) is a solid structure, and there is a strip hole (1d) on the section where the square end (8b) intersects with the front axle pipe fist (8a). The height h5=(0.25-0.40)d1 and the width b5=(0.10-0.25)d1 of the strip hole (1d) ensure that no folding and cracking defects occur during forming.

[0024] The inner concave rectangular limiting groove (1e) is arranged on the front side of the outer end surface (8h) of the front axle pipe fist (8a) at a position inwardly and downwardly deviated from the kingpin hole (1a) in the axial direction, to limit the turning angle of the knuckle installed on the front axle.

[0025] (3) Machining the outer end surface of the axle pipe fist (8a). The outer end surface (8h) of the front axle pipe fist (8a) is machined into three curved surfaces. The middle section in the width direction is a cylindrical curved surface (1c) with a curvature radius R2, and the curvature radius of the front and rear curved surfaces is R3.

[0026] (4) The end strip hole (1d) is welded with a plug (4).

[0027] (5) Machining the kingpin hole (1a) and the lock pin hole (1e).

[0028] (6) Welding the steel plate spring seat.

[0029] 3. Beneficial effects

[0030] Compared with the prior art, the hollow commercial vehicle front axle and the manufacturing method thereof have the beneficial effects that:

[0031] The hollow commercial vehicle front axle provided by the application is a hollow rectangular structure with variable cross section and wall thickness, can replace the existing forged front axle, combined welded front axle and punch-welded front axle, has light product weight, high bending and torsional strength, and is easy to match with the existing suspension system for vehicle mounting; the seamless steel pipe is selected, the hollow front axle body is formed by overall pressing after two-end diameter reduction-upsetting and bending blanking, hidden troubles caused by previous fist part body welding are completely eliminated, and the forming quality is good, and defects such as fist inner cavity folding and outer end crack are completely eliminated. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a structure schematic diagram of a forged front axle of a certain axle load 5T;

[0033] Figure 2 is a structure schematic diagram of a steel pipe combined welded front axle;

[0034] Figure 3 is a structure schematic diagram of a steel plate punch-welded front axle;

[0035] Figure 4 is a front view of the hollow commercial vehicle front axle of the application;

[0036] Figure 5 is a top view of the hollow commercial vehicle front axle of the application;

[0037] Figure 6 is each cross-sectional view of the hollow commercial vehicle front axle of the application;

[0038] Figure 7 is an H-direction view of the hollow commercial vehicle front axle of the application;

[0039] Figure 8 is a fist part schematic diagram of the hollow commercial vehicle front axle of the application;

[0040] Figure 9 is a fist part G-G cross-sectional view of the hollow commercial vehicle front axle of the application;

[0041] Figure 10 is a pipe blank schematic diagram after diameter reduction-upsetting of the hollow commercial vehicle front axle of the application;

[0042] Figure 11 is a front axle pipe main view after pressing of the hollow commercial vehicle front axle of the application;

[0043] Figure 12 is each cross-sectional view of the front and rear pipe after pressing of the hollow commercial vehicle front axle of the application;

[0044] Figure 13is the front axle tube of the hollow commercial vehicle front axle after pressing;

[0045] Figure 14 is the square end M5-M5 cross-sectional view of the front axle tube of the hollow commercial vehicle front axle after pressing.

[0046] In the above figure, 1. fist, 1a. king pin hole, 1b. thick-walled rectangular cylinder, 1c. cylindrical curved surface, 1d. strip-shaped hole, 1e. limiting groove, 1f. lock pin hole, 2. bent neck, 2a. bent round corner, 3. cross beam, 3a. middle section of cross beam, 3b. left section of cross beam, 3c. right section of cross beam, 4. welding plug, 5. upper cover, 5a. upper plate, 5b. vertical wall of upper cover, 5c. cylindrical hole, 6. lower support, 6a. base plate of lower support, 6b. vertical wall of lower support, 6c. rib plate of lower support, 6d. bar of lower support, 6e. motorcycle bolt hole, 7. reduced-diameter-upset pipe blank, 8. front axle tube, 8a. fist of front axle tube, 8b. square end, 8c. upper curved surface, 8d. lower curved surface, 8e. front curved surface, 8f. rear curved surface, 8g. top corner, 8h. outer end face of fist of front axle tube. DETAILED DESCRIPTION

[0047] Hereinafter, specific embodiments of the hollow commercial vehicle front axle and the manufacturing method thereof according to the present application will be described in detail with reference to the accompanying drawings, and those skilled in the art can clearly understand the present application and implement the present application according to these detailed descriptions.

[0048] Reference Figures 4 to 14 The present application provides a hollow commercial vehicle front axle, which is composed of an axle body and a leaf spring seat, the axle body includes a cross beam (3), bent necks (2) on both sides of the cross beam, and a fist (1) connected with the bent necks, and has a variable cross-section and variable wall thickness hollow rectangular structure as a whole, and is formed by a seamless steel pipe.

[0049] The cross beam (3) is divided into a middle section (3a) and left and right sections (3b) and (3c) on both sides, the height h1 of the rectangular cross section of the middle section (3a) is 115 mm, the face width b1 is 93 mm, and the wall thickness t1 is 13 mm, which is determined according to the bending strength and serves as a design reference for the geometric parameters of the rectangular cross section of other parts. The rectangular cross sections of the left and right sections (3b) and (3c) are the same as that of the middle section (3a), with slightly increased height and slightly decreased width, so as to ensure high bending and torsional strength. The height h2 of the left and right sections (3b) and (3c) is 123 mm, the width b2 is 80 mm, and the cross section is lifted upward, with the bottom surface lifted by H1=10 mm higher than that of the middle section (3a), so as to meet the minimum ground clearance after the installation of the leaf spring.

[0050] The inner side of the bent neck (2) is connected with the cross beam (3), and is bent upward to form a bent round corner (2a) with a radius R1=120mm, and the angle between the axis of the bent neck (2) and the horizontal line is θ1=50°. The width of the bent neck (2) at the position of the cross beam (3) is increased and the height is reduced to enhance the torsional strength, and the width b3=100mm and the height h3=98mm.

[0051] The outer side of the bent neck (2) is connected with the fist part (1), and the fist part (1) is a thick-walled rectangular cylinder (1b) with a gradually narrowed width from the inner side to the end part, and the fist part (1) is provided with a king pin hole (1a) for mounting the king pin, and the hole diameter is d1=φ47mm; the inner cavity of the thick-walled rectangular cylinder (1b) is composed of four upper and lower and front and rear inner concave surfaces, and there is a top corner between adjacent surfaces, and the top corner is not allowed to have a folding defect; the cross section passing through the axis of the king pin hole (1a) has a height h4=98mm, a width b4=88mm, and a wall thickness t4=20.5mm, which ensures sufficient bending and torsional strength. The outer end of the fist part (1) is composed of three curved surfaces, and the middle section in the width direction is a cylindrical curved surface (1c) with a curvature radius R2=40.5mm, and the central angle of the cylindrical curved surface (1c) is θ2=90°, and the curvature radius of the front and rear curved surfaces is R3=50mm; the cylindrical curved surface (1c) is provided with a strip-shaped hole (1d) at the middle part of the height, and the height h5=12.3mm and the width b5=6mm, which ensures that the fist part has high bending and shearing performance; the strip-shaped hole (1d) is welded with a plug (4). The front side of the fist part (1) is provided with an inner concave rectangular limiting groove (1e) at a position inwardly and downwardly deviated from the axis of the king pin hole (1a), which is used to limit the rotation angle of the steering knuckle mounted on the front axle. The inner side of the king pin hole (1a) is provided with a lock pin hole (1f) with a hole diameter d2=φ18mm, and the distance between the axis of the lock pin hole (1f) and the axis of the king pin hole (1a) is c1=26mm.

[0052] The steel plate spring seat of the hollow commercial vehicle front axle is composed of an upper cover (5) and a lower support (6), the upper cover (5) is in the shape of a bench and is composed of an upper plate (5a) and upper cover vertical walls (5b) on the front and back sides, the upper plate (5a) is the installation base of the steel plate spring, the upper plate (5a) is provided with a fist hole (1a) with a height H2=167.2 mm, which is the first level difference of the front axle, the axial width of the upper plate (5a) is c2=88 mm, the front-to-back length is c3=160 mm, and a cylindrical hole (5c) with a diameter d3=φ20.5 mm is arranged at the center; the upper cover vertical walls (5b) are clamped on the upper parts of the left section (3b) and the right section (3c) of the cross beam and are welded together. The lower support (6) is in the shape of a U-shaped structure with a triangular hollow, is composed of a base plate (6a), front and back base plate vertical walls (6b) above the base plate and three rib plates (6c) below the base plate, and is provided with a rib (6d) between the base plate (6a) and the base plate vertical walls (6b); the base plate vertical walls (6b) are clamped on the middle parts of the left section (3b) and the right section (3c) of the cross beam and are welded together. The three rib plates (6c) below the base plate wrap the lower parts of the left section (3b) and the right section (3c) of the cross beam. Four horse bolt holes (6e) with a hole diameter d4=φ21 mm are symmetrically arranged on the base plate (6a), the left and right hole distance of the horse bolt holes (6e) is c4=112 mm, the front and back hole distance is c5=130 mm, and the installation conditions of the front axle and the suspension are ensured, that is, c5=130 mm. The horse bolt of the suspension effectively assembles the cross beam (3), the upper cover (5) and the lower support (6) together, the stress state of the cross beam (3) is good, the service life is long, and the lightweight is facilitated.

[0053] The application also provides a manufacturing method of the hollow commercial vehicle front axle, a seamless steel pipe with an initial outer diameter D0=φ121 mm and a wall thickness t0=13 mm is selected, the hollow rectangular front axle pipe (8) is obtained by two-end diameter reduction-upsetting, bending and overall pressing forming, and finally machining, welding and other steps are performed, and the method is characterized in that:

[0054] (1) the end part of the seamless steel pipe is hot-diameter-reduced-upset to obtain a diameter-reduced-upset pipe blank (7), the end part diameter D1=φ112 mm is reduced to 0.92 times of the initial pipe blank outer diameter D0=φ121 mm, the wall thickness t 01 =31.5 mm is increased to 2.38 times of the initial wall thickness t0=13 mm, and the diameter-reduced-upset part and the undeformed area inside the pipe blank gradually change in wall thickness, and the inner cavity transition fillet radius R4=30 mm.

[0055] (2) The reduced diameter-upset tube blank (7) is bent and then integrally press formed into a hollow rectangular front axle pipe (8). The middle part of the reduced diameter-upset tube blank (7) is formed into a thin-walled rectangular cross-section beam (3) and two side bends (2), the wall thickness is basically unchanged, the height of the middle section (3a) of the beam becomes h1=115 mm, the surface width is b1=93 mm, the height of the left section (3b) and the right section (3c) of the beam becomes h2=123 mm, the surface width is b2=80 mm, and the height of the bend (2) becomes h3=98 mm, the surface width is b3=100 mm.

[0056] The end part of the reduced diameter-upset tube blank (7) becomes a front axle pipe fist (8a) and an outer side square end head (8b). The front axle pipe fist (8a) is a thick-walled cylinder with a constant height and gradually narrowing width from the inside to the end. The cross-section of the front axle pipe fist (8a) in the middle part where the king pin hole is to be machined has a height h4=97 mm, a width b4=b4=88 mm, and a wall thickness t5=34 mm. The inner cavity is composed of an inner concave upper curved surface (8c), a lower curved surface (8d), a front curved surface (8e), and a rear curved surface (8f). There is a top corner (8g) between adjacent curved surfaces, and the fillet radius at the top corner (8g) is R5=7 mm, which is not allowed to have folding and cracking defects. The square end head (8b) has a height h6=50 mm and a width b6=58 mm. The outer side of the square end head (8b) is a solid structure, and there is a strip hole (1d) in the cross-section where the square end head (8b) intersects with the front axle pipe fist (8a), which has a height h5=12.3 mm and a width b5=6 mm, ensuring that no folding and cracking defects occur during forming.

[0057] The outer end surface (8h) of the front axle pipe fist (8a) has an inner concave rectangular limiting groove (1e) on the front side surface at a position axially inward and downward of the king pin hole (1a) to limit the turning angle of the knuckle installed on the front axle.

[0058] (3) Machining the outer end curved surface of the front axle pipe fist (8a). The outer end surface (8h) of the front axle pipe fist (8a) is processed into three curved surfaces. The middle section in the width direction is a cylindrical curved surface (1c) with a curvature radius R2=40.5 mm, and the curvature radius of the front and rear curved surfaces is R3=50 mm.

[0059] (4) The end strip hole (1d) is welded with a plug (4).

[0060] (5) Machining the king pin hole (1a) and the lock pin hole (1e).

[0061] (6) Welding the steel plate spring seat.

[0062] While the application has been described above with reference to particular embodiments, it is to be understood that the application is not limited to the disclosed configurations and details, and that numerous modifications can be made within the scope of the application. The application is defined by the appended claims, and the scope of the application is intended to encompass all modifications within the scope of the claims, and any equivalents thereof.

Claims

1. A hollow commercial vehicle front axle, the hollow commercial vehicle front axle consisting of an axle body and a leaf spring seat, the axle body including a crossbeam (3), necks (2) on both sides of the crossbeam, and a fist (1) connected to the necks, the overall hollow rectangular structure with variable cross-section and wall thickness, formed as a whole by a seamless steel pipe, characterized in that: The crossbeam (3) is divided into a crossbeam middle section (3a), a crossbeam left section (3b), and a crossbeam right section (3c). The height h1, the width b1, and the wall thickness t1 of the rectangular cross section of the crossbeam middle section (3a) are determined based on the bending strength and serve as the design basis for the geometric parameters of the rectangular cross sections of other parts; the rectangular cross sections of the crossbeam left section (3b) and the crossbeam right section (3c) are the same as those of the crossbeam middle section (3a), with the height increased and the width decreased, thereby ensuring high bending and torsional strength; the height of the crossbeam left section (3b) and the crossbeam right section (3c) are h2=h1+(5-15mm), and the width is b2=b1-(5-15mm), and the cross section is raised upward, and the bottom surface is raised H1=(5-15mm) higher than that of the crossbeam middle section (3a), thereby meeting the minimum ground clearance after the leaf spring is installed; The inner side of the bending neck (2) is connected to the crossbeam and is bent upward to form a curved fillet (2a). The radius of the transition fillet is R1, and the angle between the axis of the bending neck (2) and the horizontal line is θ1. The wall thickness of the bending neck (2) is the same as that of the middle section (3a) of the crossbeam. The width is increased and the height is reduced to enhance the torsional strength. The width b3 = b1 + (5 to 20 mm) and the height h3 = h1 - (5 to 20 mm). The outer side of the bent neck (2) is connected to the fist part (1), and the fist part (1) is generally a thick-walled rectangular tube (1b) with a constant height and gradually narrowing width from the inner side to the end. A main pin hole (1a) for installing a main pin is provided on the fist part (1), and its hole diameter is φd1; the inner cavity of the rectangular tube (1b) is composed of four concave curved surfaces, upper and lower, front and back, and there are vertex angles between adjacent curved surfaces, and there is no folding defect at the vertex angle; the cross section through the axis of the main pin hole (1a) has a height h4=(0.80~0.90)h1, a width b4=(0.90~1.0)b1, and a wall thickness t4=(1.40~1.60)t1, ensuring sufficient bending and torsional strength; The outer end of the fist part (1) is composed of three curved surfaces, the curvature radius of the cylindrical curved surface (1c) in the middle section in the width direction is R2, the central angle of the cylindrical curved surface is θ4, and the curvature radius of the curved surfaces on the front and rear sides is R3; a strip hole (1d) is provided in the middle portion of the height of the cylindrical curved surface (1c), the height h5 = (0.25-0.40) d1, and the width b5 = (0.10-0.25) d1, to ensure that the fist part has high bending and shear resistance; the strip hole (1d) is welded with a welding plug (4); On the front side of the fist portion (1), located slightly inward and downward of the main pin hole (1a), an inwardly concave rectangular limiting groove (1e) is provided for limiting the rotation angle of the steering knuckle mounted on the front axle; a locking pin hole (1f) is provided slightly inward and upward of the main pin hole (1a), the hole diameter of which is φd2, and the distance between the axis of the locking pin hole (1f) and the axis of the main pin hole (1a) is c1; The leaf spring seat is composed of an upper cover (5) and a lower support (6); the upper cover (5) is clamped on the upper part of the left section (3b) and the right section (3c) of the crossbeam and welded together; the lower support (6) is clamped on the middle part of the left section (3b) and the right section (3c) of the crossbeam and welded together; by using the leaf spring seat, the riding bolts of the suspension effectively assemble the crossbeam (3), the upper cover (5) and the lower support (6), the crossbeam (3) has a good stress state, a long service life, and is easy to lighten.

2. The hollow commercial vehicle front axle according to claim 1, characterized in that: The leaf spring seat is composed of an upper cover (5) and a lower support (6). The upper cover (5) is in the shape of a bench and is composed of an upper plate (5a) and upper cover vertical walls (5b) on both sides. The upper plate is the installation base of the leaf spring. The height H2 between the upper plane of the upper plate (5a) and the fist kingpin hole (1a) is the first level drop of the front axle. The axial width of the upper plate (5a) is c2, the length in the front-back direction is c3, and a cylindrical hole (5c) with a diameter of φd3 is set in the center. The upper cover vertical walls (5b) are clamped on the upper parts of the left section (3b) and the right section (3c) of the crossbeam and are welded together. The lower support (6) is generally in a U-shaped structure with a triangular hollow, and is composed of a base plate (6a), front and rear base plate vertical walls (6b) above the base plate, and three ribs (6c) below the base plate, and a rib (6d) is provided between the base plate (6a) and the base plate vertical wall (6b); the base plate vertical wall (6b) is clamped in the middle of the left section (3b) and the right section (3c) of the cross beam and welded together, and the three ribs (6c) below the base plate cover the lower part of the left section (3b) and the right section (3c) of the cross beam; four riding bolt holes (6e) are symmetrically provided on the base plate (6a), with a hole diameter of φd4, and the left and right hole spacing of the riding bolt holes (6e) is c4 and the front and rear hole spacing is c5, so as to ensure the installation conditions of the front axle and the suspension, that is, c5=b2+(45-50mm).

3. A method for manufacturing a hollow commercial vehicle front axle according to claim 1 or 2, comprising selecting a seamless steel tube with an initial outer diameter D0 and an initial wall thickness t0, reducing the diameter of the tube at both ends, upsetting the tube, and bending the tube to form a blank, followed by integral press forming to obtain a hollow rectangular front axle tube, and finally performing machining and welding steps, wherein: (1) The end of the seamless steel pipe is hot-reduced and upset to obtain a reduced-upset tube blank (7), the end diameter D1 is reduced to 0.85 to 0.95 times the initial outer diameter D0, and the wall thickness t 01 Increase to 2.2 to 2.5 times of the initial wall thickness t0, and the wall thickness of the tube blank shrinkage-upsetting part and the inner undeformed area gradually changes, and the inner cavity transition fillet radius R4 is not less than 20mm; (2) After the reduced-diameter-upsetting tube blank (7) is bent, the tube is integrally pressed to obtain a hollow rectangular front axle tube (8). The middle portion of the reduced-diameter-upsetting tube blank (7) is formed into a thin-walled rectangular cross-section beam (3) and necks (2) on both sides. The wall thickness remains basically unchanged. The height of the middle section (3a) of the crossbeam is changed to h1 and the width is b1. The height of the left section (3b) and the right section (3c) of the crossbeam are changed to h2 and the width is b2. The height of the neck (2) is changed to h3 and the width is b3. The end of the reduced-upsetting tube blank (7) becomes the front axle tube fist (8a) and the outer square end (8b); the front axle tube fist (8a) is generally a thick-walled tube with a constant height and gradually narrowing width from the inside to the end. On the cross-section of the middle part of the front axle tube fist (8a) where the kingpin hole is to be processed, the height h4=(0.80~0.90)h1, the width b4=(0.90~1.0)b1, the wall thickness t5=(2.40~2.70)t1, and the inner cavity is composed of the concave upper curved surface (8c), the lower curved surface (8d), the front curved surface (8e), and the rear curved surface (8f). There is a vertex angle (8g) between adjacent curved surfaces, the fillet radius R5 at the vertex angle (8g) is not less than 5mm, and there are no folding or crack defects; the square end (8b) has a height h6=(0.45~0.60)h1 and a width b6=(0.55~0.70)b1; the outer side of the square end (8b) is a solid structure, and there is a strip hole (1d) on the cross section intersecting with the fist part (8a) of the front axle pipe, with a height h5=(0.25~0.40)d1 and a width b5=(0.10~0.25)d1, to ensure that there are no folding or crack defects during forming; On the front side surface of the outer end face (8h) of the fist portion of the front axle pipe, located axially inward and slightly below the main pin hole (1a), an inwardly concave rectangular limiting groove (1e) is provided to limit the rotation angle of the steering knuckle installed on the front axle; (3) Machining the outer end surface of the fist portion (8a) of the front axle tube fitting, and processing the outer end surface (8h) of the fist portion (8a) of the front axle tube fitting into three curved surfaces, wherein the middle section in the width direction is a cylindrical curved surface (1c) with a curvature radius of R2, and the curvature radius of the curved surfaces on the front and rear sides is R3; (4) The end strip hole (1d) is welded firmly with welding plug (4); (5) Machine the kingpin hole (1a) and lock pin hole (1f); (6) Welding the leaf spring seat.

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