JPH0751749A - Method for bending thick metallic material - Google Patents

Abstract

PURPOSE:To enable the bending work of a metallic material without requiring a large pressure by applying a pressure at a heated place with a die for bending while locally heating a place to be bent of a thick metallic material by heating electrically, thereby performing a bending work. CONSTITUTION:A material W to be worked which is a thick metallic material such as a thick billet is inserted between a punch 1 and a die 2, and pressurized by an air cylinder 4 while the punch 1 is pushed downward by applying a pressure so that the paired electrodes 3 are made into contact with the material W to be worked. On the other hand, when the electrodes 3 come into contact with the lower surface of the material W to be worked, a large amount of current is made to flow through the electrodes 3. Then, a part of the material W to be worked is locally heated by electrical heating, and since a locally heated part Wh is softened when it reaches near a melting point, a bending work can be performed almost without applying a pressure. Therefore, it follows that the bending work is performed to only a part other than the locally heated part Wh.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a method of bending a thick plate metal material such as a steel plate material.

[0002]

2. Description of the Related Art Many machines, including machine tools, are formed into complicated shapes, but the major structural material used in them is thick steel plates, which are simply fused and cut. It is a flat plate material. Thus, in order to make one machine, many constituent members having different sizes, thicknesses, etc. are required, and conventionally, those constituent members were joined by welding. Since it was a manual work that required skill and was backed by the experience and intuition of a person, the work cost was high, which was one of the causes of the high cost of the machine.

Therefore, as one method of reducing the cost of the machine, it is conceivable to reduce the number of parts and reduce the welding work. For example, there is a method of reducing welding work by bending.

However, in a conventional bending machine such as a press brake, when a thick plate is used, a large pressing force is required. Therefore, the strength of the frame supporting it and the strength of the die must be increased. As a result, the bending of thick plates is rarely performed.

Therefore, attempts have been made to hot-bend the plate by placing it in an electric furnace to heat it or heat it with a flame burner and then bend it, or cold-bend it with a press. However, the hot bending method is hardly used because it takes time to heat, and the cold bending method is possible if a large pressing force can be generated by a press machine. Since it is difficult to predict the amount of deformation due to springback after removal, it is currently not used for bending thick plates.

[0006]

SUMMARY OF THE INVENTION In view of the above-mentioned conventional techniques, the present invention provides a metal plate material such as a thick steel plate,
It is an object of the present invention to provide a method capable of bending without requiring a large pressing force.

[0007]

SUMMARY OF THE INVENTION The present invention has been made for the purpose of solving the above-mentioned problems, and the structure thereof is such that a portion of a thick metal plate to be bent is locally heated by electric heating. A bending die is used to apply a pressing force to the heated portion to perform bending.

That is, the inventor of the present invention has conducted extensive research in order to solve the above-mentioned problems. As a result, the portion of the thick plate metal material to be bent is locally heated by electric heating and is bent. It is known that the problem of the prior art can be solved by locally applying hot bending by applying a large pressing force to the mold for press without causing deformation such as springback after pressurization. Then, the present invention has been completed.

[0009]

According to the present invention, when a large current is applied to a portion of a thick plate metal material to be bent, the portion generates heat due to the resistance of the metal material and reaches a temperature near the melting temperature.
A desired bending process can be performed with a small pressing force, and the deformation of the spring back or the like after removing the pressing force is extremely small.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an example of implementing the present invention will be described with reference to the drawings. FIG. 1 is a schematic explanatory diagram before starting the bending process according to the present invention, and FIG. 2 is a schematic explanatory diagram at the end of the bending process.

The bending method of the present invention, as shown in FIG.
A work material W, which is a thick metal material such as a thick steel plate, is inserted between the punch 1 and the die 2 and a pressing force is applied to push down the punch 1 at the same time.
While pressing the paired electrodes 3 so as to contact the workpiece W, while the electrode 3 contacts the lower surface of the workpiece W, when a large current is passed between the electrodes 3 and 3, the workpiece 3 is heated by energization heating. Material W
Since a part of the local heating part Wh is locally heated and the local heating part Wh reaches the melting temperature and softens, it can be bent with almost no pressing force, and therefore only the part excluding the local heating part Wh is folded. It suffices to perform bending work, and it is possible to perform bending work with an extremely small pressing force. .

FIG. 2 shows a state when the machining is completed. In this state, the energization of the electrodes 3 and 3 is stopped, but the electrodes 3 and 3 are separated from the workpiece W by the air cylinder 4. Since the contact is maintained, it is possible to pass an electric current whenever necessary and the heating can be maintained.

[0013]

EFFECTS OF THE INVENTION The present invention is as described above, and a portion of a thick plate metal material to be bent is locally heated by electric heating while a pressure is applied to the portion to be bent. Since the thick metal plate can be bent with a small pressing force, it can be bent by a bending machine such as a press brake which has been impossible in the past.

Further, in the present invention, since the bending process is carried out in a heated state, the residual stress is small and the deformation such as the spring back is also small, so that the processing accuracy becomes extremely good.

Further, according to the present invention, as compared with the method of heating with an electric furnace or the method of heating with a burner, the current is directly and locally applied to perform heating, so that not only the energy efficiency is high, but also the heating time is high. Also, because the cooling time can be shortened, it is easy to maintain quality. In addition, the heating pattern is always the same, and the variation in heating when repeated heating is small, so that the processing accuracy is almost the same for the same workpiece, and therefore uniform bending is always possible. .

[Brief description of drawings]

FIG. 1 is a schematic explanatory view before starting a bending process according to the present invention.

FIG. 2 is a schematic explanatory view at the end of bending according to the present invention.

[Explanation of symbols]

 1 punch 2 die 3 electrode W work material Wh local heating part of work material

Claims (1)

[Claims] 1. A bending process is performed by locally heating a portion of a thick plate metal material to be bent by electric heating while applying a pressure to the heating portion with a bending die. Bending method for thick metal plate.