Excel shaft for automobile and its manufacturing

Abstract

The present invention relates to a method for manufacturing an axle shaft of an automobile and an axle shaft manufactured by such method, and is characterized in that it is manufactured using tubes rather than round bars, and two tubes of different materials are combined and then integrated using extrusion to create the required external shape. The gist of the method is characterized by preparing a large-diameter material (1) and a small-diameter material (1') having a small outer diameter of different materials, inserting the small-diameter material (1') into the interior of the large-diameter material (1), and simultaneously performing an extrusion process one or more times while the small-diameter material (1') is inserted into the interior of the large-diameter material (1) so that the small-diameter material (1') is in close contact with the inner surface of the large-diameter material (1) and becomes an integral, thereby reducing the diameter, and by contracting the other side in the same way as the above process to make it an integral, and forming a diameter reduction part (3) and a spline part (4) to form a spline (2) at both ends, and forming a spline (2) through rolling or cutting on the spline part (4) and processing a ring groove (5).

Description

Technology Field

[0001] The present invention relates to a method for manufacturing an axle shaft that transmits driving force generated from an engine in an automobile to a wheel through a transmission, and to an axle shaft manufactured by such method. In particular, it is characterized by manufacturing using a tube rather than a round bar, and by combining two tubes of different materials and then integrating them using extrusion to create the required external shape. Background Technology

[0002] Typically, in automobiles, rotational force generated by the engine is shifted through a transmission and then transmitted to the wheels via an axle shaft to enable driving; the axle shaft transmits rotational power through splines formed on both ends. Conventionally, these axle shafts were made by turning round bar materials. However, during driving, vibration noise caused by body shaking and engine output was directly transmitted to the axle shaft, resulting in critical defects in braking and drive quality. Consequently, there was a disadvantage in that additional noise-reducing pads had to be attached. Furthermore, while some vehicle models constructed axle shafts by welding round bars to both ends of tubes, this method was time-consuming and complicated, and suffered from frequent defects at the welded joints. Additionally, although a method of manufacturing axle shafts using tubes was devised, there was a need for further cost reduction and a greater demand for noise and vibration reduction, leading to a need for improved solutions. The problem to be solved

[0003] The present invention, devised in consideration of the aforementioned problems, aims to provide an axle shaft in which strength is significantly increased and noise and vibration are further reduced at a lower cost by inserting a small-diameter tube into the interior of a large-diameter tube, forming the required outer shape by extruding both ends (reducing the diameter), and forming splines and other shapes on the compressed portion. Effects of the invention

[0005] As described above, the present invention provides a tube-type axle shaft by using two tubular materials of different diameters and materials through a relatively simple extrusion method, which is a useful invention that further improves the quality of the axle shaft by reducing manufacturing costs, reducing weight, and further improving durability, and very effectively preventing the occurrence of noise and vibration. Brief explanation of the drawing

[0006] FIG. 1 is a cross-sectional view of the process steps illustrating the extrusion process according to the present invention. FIG. 2 is a partial cross-sectional view showing another embodiment of the present invention. Specific details for implementing the invention

[0007] The present invention is characterized by preparing tubular large-diameter and small-diameter materials having appropriate length and strength, inserting the small-diameter tube into the large-diameter tube, and simultaneously performing tube compression, and manufacturing splines and other necessary shapes on the compressed portions. The present invention will be examined in detail below with reference to the attached drawings. FIG. 1 is a flowchart explaining the manufacturing process of the present invention in sequence, and FIG. 2 shows another embodiment of the present invention.

[0008] Process 1: Material Preparation

[0009] The present invention prepares tubular materials (1) and (1') made of two materials having a desired strength as an axle shaft, wherein a large-diameter material (1) having a final outer diameter when completed as an axle shaft and a small-diameter material (1') having an outer diameter 45 to 50% smaller than that are prepared, and the following extrusion process is performed simultaneously with the small-diameter material (1') inserted into the large-diameter material (1). The lengths of the large-diameter material (1) and the small-diameter material (1') can be designed considering the elongation rate, etc., in consideration of the length of the final completed product. When the large-diameter material (1) is manufactured and used as an axle shaft, an excellent material is used that has no problems with appearance, surface treatment, strength, etc., and the small-diameter material (1') is used that is relatively inexpensive yet has excellent strength-maintaining properties such as bending and twisting, thereby allowing for overall material cost reduction while maintaining excellent performance.

[0010] Second process: One-sided shaft tube

[0011] By inserting a small-diameter material (1') into the interior of a large-diameter material (1) and simultaneously performing an extrusion process, the small-diameter material (1') is compressed into the inner surface of the large-diameter material (1) and becomes closely attached to one another, thereby reducing the diameter. At this time, the thickness of the large-diameter material is made thicker than its initial state. Depending on the degree of reduction, the performance of the machine, and the characteristics of the material, this extrusion process may achieve the desired dimensions in a single step, but the desired dimensions may also be achieved through multiple compression steps.

[0012] 3rd Process: Other side shaft tube

[0013] The other side is compressed in the same way as the above process to be integrated. Therefore, when the above second and third processes are carried out, the large diameter material (1) and the small diameter material (1') are integrated. At this time, since compression and extrusion were not performed on the central part, a space (s) is formed between the large diameter material (1) and the small diameter material (1').

[0014] Process 4: Reduction of diameter at both ends

[0015] To form splines (2) at both ends, a diameter reduction section (3) and a spline section (4) are formed. This processing is performed using a spline die or by cutting.

[0016] Fifth Process: Spline Formation

[0017] The spline (2) is formed on the spline section (4) through rolling or cutting, and the ring groove (5) is machined to complete the spline section.

[0018] Process 6: Finishing

[0019] The manufacturing process is completed by cleaning the surface of the finished product, applying rust prevention treatment, and then sorting out defects through inspection. The axle shaft (20) completed in the above manner is configured to be integrated with a small diameter material (1') inserted inside a large diameter material (1), and the central part is formed such that the large diameter material (1) and the small diameter material (1') retain their original diameters while maintaining a space (s) in the center, and both ends are integrated by the large diameter material (1) being simultaneously compressed and in close contact with the small diameter material (1'), and a spline (2) is formed on the outer surface of the end. In addition, as another embodiment of the present invention, a small diameter material (1") with a short length may be used to make only one side of the large diameter material (1) into a double tubular shape. In this case, the opposite side without the small diameter material (1") must be molded to have a thicker thickness of the large diameter material (1) during extrusion to maintain a sufficient thickness. According to the present invention, since the axle shaft is formed as a tube using a double tube overall, the interior becomes hollow, which reduces weight. Furthermore, since there are no welding connections and the density of the material is improved through plastic processing by extrusion, it is possible to obtain a strong resistance to torsional stress or rotational torque and high tensile strength. In particular, since the small-diameter material inside can be made of a low-cost material, conditions are created to reduce overall manufacturing costs. Additionally, since the small-diameter material inside (1') has a small degree of compression, a stronger material can be used, so it acts as a frame inside and can further improve strength. Moreover, the double tube reduces the generation of noise or vibration, and minimizes the transmission of such noise or vibration to the wheels or transmission. The ride comfort, braking, and driving quality are greatly improved to the extent that a separate configuration for noise suppression is not required. Explanation of the symbols

[0020] 1: Large diameter material 1': Small diameter material 2: Spline 3: Diameter reduction section 4: Spline section 5: Ring home 20: Axle shaft

Claims

Claim 1 A process of preparing tubular materials (1)(1') made of two different materials, wherein a large-diameter material (1) having a final outer diameter when completed as an axle shaft and a small-diameter material (1') having an outer diameter 45 to 50% smaller than that are prepared, and a process of preparing for extrusion by inserting the small-diameter material (1') into the interior of the large-diameter material (1); a process of performing an extrusion process one or more times on one end while the small-diameter material (1') is inserted into the interior of the large-diameter material (1) so that both the large-diameter material (1) and the small-diameter material (1') are compressed, and the small-diameter material (1') adheres to the inner surface of the large-diameter material (1) to form an integrated structure, thereby reducing the diameter, wherein the thickness of the large-diameter material becomes thicker than its initial state; and a process of compressing the other end in the same manner as the above process to form an integrated structure, so that at both ends, the large-diameter material (1) and A method for manufacturing an axle shaft for an automobile, characterized by comprising: a process in which a small diameter material (1') is compressed and integrated, while the central part is not compressed so that a space (s) is maintained between a large diameter material (1) and a small diameter material (1'); a process in which a diameter reduction part (3) and a spline part (4) are formed to form splines (2) at both ends; a process in which splines (2) are formed and ring grooves (5) are machined through rolling or cutting on the spline part (4); and a process in which the surface of the finished product is cleaned and rust-preventive treated, and then defects are sorted through inspection. Claim 2 An axle shaft for an automobile, characterized in that it is configured such that a small diameter material (1') is inserted into the interior of a large diameter material (1) and integrated by the method of claim 1, wherein the central part maintains a space (s) between the large diameter material (1) and the small diameter material (1'), and both ends are integrated by being tightly joined together with both the large diameter material (1) and the small diameter material (1'), and splines (2) are formed on the outer surfaces of both ends.

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