KR100658510B1 - Method of manufacturing tool for elimination of geometrical defect in tube bending - Google Patents

Abstract

A method of manufacturing a clamp for removing shape defects of a tube in tube bending is provided to prevent external appearance of the tube from being damaged even after a bending process, and increase an overall yield resultingly by performing the bending process smoothly, thereby reducing defects of a product remarkably even in a subsequent process. In a clamp of a bending machine, comprising a first clamp die(10) and a second clamp die(20) engaged with the first clamp die to bend the tube workpiece to a predetermined curvature by self-rotation of the tube workpiece before performing a process by interposing a tube workpiece between the first clamp die and the second clamp die, a method of manufacturing a clamp for removing shape defects of a tube in tube bending is characterized in that the clamp dies are formed in such a manner that one of the first clamp die or the second clamp die has a larger tube contact area than the other clamp die, wherein a front end(face)(11) with a larger tube contact area of the one clamp die(10) contacted with the tube is formed at a predetermined angle relative to a front end(face)(21) of the other clamp die(20) contacted with the tube.

Description

METHODS OF MANUFACTURING TOOL FOR ELIMINATION OF GEOMETRICAL DEFECT IN TUBE BENDING}

1 is a view showing a state in which a process tube is clamped to a bending clamp according to the prior art;

2 is a view showing the appearance of the tube immediately after bending by using the bending clamp according to the prior art,

3 shows a perspective view of a clamp for clamping a tube and a state in which the tube is clamped, according to the invention;

4 is a view showing the appearance of a tube immediately after bending by using the bending clamp according to the present invention; and

Figure 5 shows the appearance before and after the improvement of the tube bent by the clamp according to the prior art and the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tube bending device for bending a steel tube or a nonferrous metal tube material to a certain curvature applied to a hydroforming process, and more particularly, to improve the shape of a clamp for clamping a tube for bending, and then a tube after bending. The present invention relates to a clamp manufacturing method for removing a defect in the shape of the tube which is configured to prevent the defect formed in the exterior.

Typically, automotive parts use products that have undergone a hydroforming process. Exhaust system parts, engine cradle parts, chassis, etc. of the hydroformed products are used a lot of light and high strength products are applied.

Generally, the hydroforming process consists of a lower mold with a lower die and an upper mold with an upper die. The upper and lower molds are configured to be selectively closed with each other. At this time, the cavity profile corresponding to the appearance of the product is formed on the die surface in contact with each other of the upper and lower molds, and a predetermined blank material (for example, tubular material, plate material, etc.) is inserted into the cavity profile. After closing the mold, a predetermined liquid is loaded into the material, and a predetermined pressure is applied to expand the material to match the cavity profile of the die.

At this time, there is a limit to bending the material at a desired curvature and angle during the hydroforming process, and since the high pressure fluid is used, the material is preformed before the hydroforming process in a shape similar to the product. At this time, the material is molded into a curved shape by a predetermined bending device.

In order to bend the above-described material tube, a mold set for performing each function is required, and a bending machine for mounting these molds to make a straight line or a rotational motion required for the bending process is required. Since bending of metal tubes, especially steel pipes, requires a great force, hydraulic bending machines are common, and computerized numerical control (CNC) bending machines are becoming common for accurate and repeatable machining.

The bending die is determined by the shape of the final product and is largely determined by a bending die, a clamp die, a pressure die, a wiper die, a mandrel, and a clamping chuck. chuck). Among them, the clamp is a mold that performs a substantial bending process by rotating while strongly supporting the tip of the tube, and should be free from slipping with the tube during the rotation. When this slip occurs, not only scratches on the surface of the tube, but also a large wrinkle occurs because the tube does not flow smoothly into the mold. Therefore, in order to perform the function of the clamp, the length of the clamp is generally appropriate to twice the outer diameter of the tube and a minimum length of 1.5 times is required.

However, when a complicated shape is required, in particular in the case of automobile parts, a short distance between the bending points is often insufficient to secure a sufficient clamp length. In this case, the short clamp needs to be supplemented by providing roughness to the surface in contact with the tube so as to have sufficient frictional force. Another problem, however, is that the tip of the tube is pressed by a rotating clamp, creating a mark, as shown in Figure 2. This is unavoidable due to the short clamps and conventional shapes as shown in FIGS. 1 and 2, leading to larger defects in the molding process after bending as well as in appearance.

In order to solve the above problems, an object of the present invention is to provide a clamp manufacturing method for removing the shape defects when bending the tube is implemented so that the appearance of the tube is not damaged even after the bending process.

It is another object of the present invention to provide a clamp manufacturing method for removing a defect in the shape of the tube bending to perform a smooth bending process to significantly reduce the defective rate of the product in the subsequent process, as a result, the overall yield can be increased.

In order to solve the above object, the present invention is configured to be engaged with the first clamp die, the first clamp die, the intervening material tube between the first clamp die and the second clamp die in its own rotation. Wherein the clamp of one bending machine is configured to bend at a certain curvature prior to processing, wherein either the first clamp die or the second clamp die is formed so that the tube contact surface is wider than the other clamp die. .

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the case where it is determined that the gist of the present invention may be unnecessarily obscured, the detailed description thereof will be omitted.

Fig. 3 shows the design shape of the clamp die 10 according to the present invention, and the portion 1 shown in dark color is added to the clamp die having a rectangular parallelepiped shape. 3 shows the state in which the clamp die 10 manufactured as described above is mounted on the bending machine. At this time, the part 1 of the clamp die may be integrally formed when manufacturing the existing clamp. However, the present invention is not limited thereto, and may be additionally attached or secured to an existing clamp device. Thus, the clamp die 10 may have a contact surface with a wider tube as indicated by reference numeral 2 of FIG. 3.
As shown in the lower part of FIG. 3, a tube is interposed between two clamp dies 10 and 20, and the clamp die rotates in a predetermined direction to bend the tube.
In this case, the tube contact tip portion (surface) 11 of the clamp die 10 having the relatively wider tube contact surface and the tube contact tip portion (surface) 21 of the remaining clamp die 20 may be formed to have a predetermined angle. Can be. Preferably, the angle A formed between the tube tip (face) 11 of the one clamp die 10 and the tube tip (face) 21 of the other clamp die 20 may be formed at an obtuse angle. .

Referring to the operation principle of the present invention configured as described above in detail. The part 1 added to the clamp makes it possible to expand the area in contact with the tube. That is, in the conventional rectangular parallelepiped clamp, excessive stress is concentrated and pressed at the edge of the surface contacting the tube, but in the present invention, as shown in FIG. 4, shape defects occur while maintaining the length of the clamp. Increasing the contact area and length of the part can greatly prevent the occurrence of defects.

5 shows a shape of a tube bent by using a conventional clamp and a clamp according to the present invention, and the diameter and thickness measurement results are shown in Table 1 below. As shown in Table 1, it can be seen that the shape defect does not appear in the tube bent by the clamp mold according to the present invention.

Apparently, there are many ways to modify these embodiments while remaining within the scope of the claims. In other words, there may be many other ways in which the invention may be practiced without departing from the scope of the following claims.

The clamp device according to the present invention has the effect of significantly preventing the occurrence of defects by extending the contact area and the length of the portion where the shape defects of the tube occur while maintaining the length of the clamp for holding the tube.

Claims (3)

A clamp of a bending machine configured to be engaged with the first clamp die and the first clamp die, and to be bent to a certain curvature before the process by self-rotation by interposing a material tube between the first clamp die and the second clamp die. In Any one of the first clamp die or the second clamp die is formed so that the tube contact surface is wider than the other one of the clamp die, characterized in that the clamp manufacturing method for removing the shape defect during tube bending. The method of claim 1, Manufacture of clamps for removing shape defects during tube bending, characterized in that the tube contact tip (face) of the clamp die having the relatively wider tube contact surface and the tube contact tip (face) of the other clamp die are formed to have a predetermined angle. Way. The method of claim 2, The angle between the tube front end (surface) of the one clamp die and the tube front end (surface) of the other clamp die is formed at an obtuse angle, characterized in that the clamp manufacturing method for removing the shape defect during tube bending.

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