DESC:PISTON ROD FOR SHOCK ABSORBER AND METHOD FOR FABRICATING THEREOF

Field of the invention

The present invention relates to a suspension system of an automobile, and more particularly, the present invention relates to a piston rod for a shock absorber and a method for fabricating thereof.

Background of the invention

Existing piston rods are made from solid steel rods. The ends of these rods are machined to get a desired shape. However, weight of each solid piston rod is around a kilogram hence the raw material cost can be higher. Also, the bending strength of the solid piston rods is comparatively lower.

Accordingly, there exist a need to provide a piston rod for a shock absorber and a method for fabricating the piston rod that overcomes the above mentioned drawbacks of the prior art.

Objects of the invention

An object of the present invention is to provide a piston rod with good bending and tensile strength.

Another object of the present invention is to reduce weight and cost of the piston rod used in a shock absorber.

Summary of the invention

The present invention provides a piston rod for a shock absorber. The piston rod comprises of a hollow tube having solid ends joined on each end of the hollow tube, thus configuring the hollow tube therebetween. In another aspect, the present invention discloses a method for fabricating the piston rod. The piston rod is formed by friction welding of the hollow tube and the solid ends. Particularly, the hollow tube and the solid ends are made up of low carbon steel thereby fabricating the light weight piston rod. Further, the piston rod fabricated by the method has good bending and tensile strength properties.

Brief description of the drawings

The objectives and advantages of the present invention will become apparent from the following description read in accordance with the accompanying drawings wherein,

Figure 1 shows a piston rod for a shock absorber, in accordance with the present invention;

Figure 2 shows an exploded view of the piston rod of figure 1; and

Figure 3 shows a flowchart for a method for fabricating the piston rod, in accordance with the present invention.

Detailed description of the invention

The foregoing objects of the invention are accomplished and the problems and shortcomings associated with the prior art techniques and approaches are overcome by the present invention as described below in the preferred embodiment.

The present invention provides a piston rod for a shock absorber and a method for fabricating thereof. The piston rod is formed by friction welding of a hollow tube and solid ends, applicable for shock absorber strut rods. The piston rod has good bending and tensile strength and has a weight 50% lesser as compared to the piston rod of the prior art.

The present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the various figures. These reference numbers are shown in bracket in the following description.

Referring now to figure 1 and 2, in an aspect, there is shown a piston rod (100) for a shock absorber (not shown) in accordance with the present invention. In an embodiment, the piston rod (100) is made of low carbon steel hollow tube (hereinafter referred to as ‘the hollow tube (20)’). The hollow tube (20) reduces weight and mass of the piston rod (100). Further, ends of the hollow tube (20) are machined to get a desired shape. In a preferred embodiment, solid ends (40), made of low carbon steel, are joined together to the ends of the hollow tube (20) by friction welding. However, it may be evident to those skilled in the art that other processes known in the art to join the solid ends (40) to the ends of the hollow tube (20) may be used.

Referring now to figure 3, a method (hereinafter referred to as ‘the method (200)’) for fabricating the piston rod (100) in accordance with the present invention is shown.
The method (200) starts at step (10).

At step (20), the method (200) includes holding the hollow tube (20) and the solid end (40) in a fixture (not shown) at a position to configure the hollow tube (20) there between the solid end (40), and rotating any one solid end (40). The solid end (40) under rotation is referred to as a rotating solid end.

At step (30), the method (200) includes applying force on the hollow tube (20) and bringing it in contact with the rotating solid end wherein both the ends at contact will turn red hot because of friction generated between surfaces of the end of the hollow tube (20) and said rotating solid end (40) thereof due to their relative motion.

At step (40), the method (200) further includes giving a forging blow when the desired temperature is achieved at the joining ends thereby completing the process of joining to form the piston rod (100). Thereafter, the excess material is machined to get the right size. The method (200) ends at step (50).

The above said process is repeated for the other end of the piston rod.

Advantages of the invention

• The piston rod (100) fabricated by the method (200) has higher tensile strength than the existing steel rod fabricated by conventional welding process.
• The method (200) helps in achieving uniform welding of the hollow tube (20) and the solid end (40) to fabricate the piston rod (100).
• The molecular structure is homogenous at the weld joint.
• No filler material is used while fabricating the piston rod (100) using the method (200).

The foregoing objects of the invention are accomplished and the problems and shortcomings associated with prior art techniques and approaches are overcome by the present invention described in the present embodiment. Detailed descriptions of the preferred embodiment are provided herein; however, it is to be understood that the present invention may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims and as a representative basis for teaching one skilled in the art to employ the present invention in virtually any appropriately detailed system, structure, or matter. The embodiments of the invention as described above and the methods disclosed herein will suggest further modification and alterations to those skilled in the art. Such further modifications and alterations may be made without departing from the spirit and scope of the invention.

,CLAIMS:We claim:

1. A piston rod (100) for a shock absorber, the piston rod (100) comprising of
a) a hollow tube (20) selected from low carbon steel; and
b) solid end (40) capable of joining on each ends of the hollow tube (20) to configure the hollow tube (20) therebetween;
wherein, the hollow tube (20) and the solid end (40) are joined together by friction welding thereby fabricating a light weight piston rod (100) having good bending and tensile strength.

2. A method (200) for fabricating a piston rod (100), the method (200) comprising the steps of:
a) holding the hollow tube (20) and the solid end (40) in a fixture at a position to configure the hollow tube (20) therebetween said solid end (40) and rotating any one of the solid end (40), wherein the hollow tube (20) and solid end (40) being selected from a low carbon steel;
b) forcing the hollow tube (20) towards the rotating solid end (40) such that the friction generated between the surfaces of the end of the hollow tube (20) and the rotating solid end (40) forms a joint therebetween;
c) forging blow finishes the joints connecting the hollow tube (20) and said solid end (40) together;
d) repeating the steps a-c for joining together other end of the hollow tube (20) and the other solid end (40) to fabricate a piston rod (100); and
e) machining the excess of material to get a desired size at the joint.