JP2987006B2 - Bending method of painted steel plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for bending a coated steel plate such as a reflector for lighting equipment.

[0002]

2. Description of the Related Art FIG. 4 shows an example of the appearance of a reflector 10 for a fluorescent lamp. The reflecting plate 10 is formed by bending a long coated steel plate along a bending line position with a predetermined outside radius R.

FIG. 5 shows a state (partial cross-sectional view) at the time of bending by the bending punch 1. Although there are several types of products with different plate thicknesses, they are conventionally processed with the same bending mold. For example, in the case of varieties workpiece 3 ', bending clearance processed was adjusted to t _B, when switching to the varieties of the work 3, as bending clearance is t _A,
Processing is performed after adjusting to the state shown by the broken line.

[0004]

Therefore, it is necessary to adjust the bending die every time the type is changed, and it takes time to set up. Japanese Patent Application Laid-Open No. 54-145741 is a conventional example. However, this conventional example cannot cope with a case in which the thickness of a work is different, and has a problem that a protective sheet is disposable. The present invention has been made to solve the above-described problem, and an object of the present invention is to make it possible to use the same bending mold for workpieces having different plate thicknesses and reduce costs. To provide a method for bending a coated steel sheet.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention superimposes a work and a protective sheet on each other, performs bending processing so that the total thickness of the work and the protective sheet is substantially the same, and adjusts the bending line of the work. On the other hand, the protective sheet is supplied and wound from a right angle direction. In this case, the surface pressure at the time of bending is measured, and the bending is performed at a pressure not exceeding the surface pressure of the protective sheet or the coating film. Further, the present invention is characterized in that a protective sheet is overlapped on the outer surface of the work and bent.

[0006]

With this structure, according to the present invention, (1) one or a plurality of protective sheets having different thicknesses are supplied into a bending mold so that the total thickness when superimposed is always substantially the same. Therefore, the workpiece is bent simultaneously with the workpiece. (2) The protective sheet is supplied or wound from a direction perpendicular to the bending line of the work. (3) The working pressure during bending is measured, and the upper limit is set so as not to exceed the facing pressure of the protective sheet or the withstand pressure of the coating film, and the bending is performed at a pressure lower than that. (4) The protective sheet is superposed on the external surface of the work and bent to prevent processing scratches on the coating film surface.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a partial cross-sectional view of a workpiece in a bending state. In this embodiment, a work 3 is arranged between a bending punch 1 and a die 2, a protective sheet 4 is superimposed on the work 3, and the clearance of the bending mold is reduced by the thickness t _{A of the} work 3.
And the thickness t _x of the protective sheet 4 (t _x + t _A ). As the protective sheet 4, for example, plastic (PET or the like) is used.

FIG. 2 shows a bending die 7 for bending the work 3.
And the supply and winding states of the protection sheets 4 and 5 are shown. The protection sheets 4 and 5 are supplied and wound from a direction substantially perpendicular to the bending line of the work 3. Thereby, the elongation of the protective sheets 4 and 5 generated during the bending can be absorbed as much as possible. Although the protective sheets 4 and 5 are slightly stretched at the bending corners, they can be used repeatedly by shifting the supply position when reusing after winding.

FIG. 3 shows a state in which a work 3 'having a thickness smaller than that of the work 3 is processed. The total thickness of the work 3' and the protection sheets 4, 5 is substantially the same as the total thickness in the above embodiment. I am trying to be. That is, the thickness t _Y of the protective sheet 5 is (t _x + t _A ) = (t
_x + t _Y + t _B) to as to be, t _Y = and has a (t _A -t _B).

Further, as shown in FIGS. 1 and 3, a pressure sensor 6 is provided on the bending punch 1 so that the surface pressure during processing is actually measured. And, so that the surface pressure during bending does not exceed the surface pressure of the protective sheet and the coating film,
The upper limit has been set. If the surface pressure exceeds the withstand pressure due to a change in the thickness of the coating film or the like, an abnormal state is displayed (not shown).

Further, as shown in FIGS. 1 to 3, the protective sheets 4 and 5 are overlapped on the outer surfaces of the works 3 and 3 'to prevent scratches on the outer surfaces due to bending.

[0012]

As described above, according to the present invention, a work and a protection sheet are overlapped, and the work and the protection sheet are bent so that the total thickness of the work and the protection sheet are substantially the same. By processing and supplying a protective sheet from a direction perpendicular to the bending line of the work, the surface pressure during bending can be measured to further protect the protective sheet and coating film. By performing the bending at a pressure not exceeding the surface pressure, the protective sheet can be used repeatedly, and the cost can be reduced. Furthermore, by forming a protective sheet on the external surface of the work and bending the protective sheet, it is possible to prevent scratches and cracks on the painted surface of the work and to obtain a high-quality bent product.

[0013]

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a state in which a work is processed by stacking one protective sheet.

FIG. 2 is a diagram showing a state in which a bending mold for bending a workpiece and a protective sheet are supplied and wound.

FIG. 3 is a diagram illustrating a state in which a plurality of protective sheets are stacked to process a workpiece.

FIG. 4 is a view showing the appearance of a reflector for a fluorescent lamp.

FIG. 5 is a diagram showing a conventional example when bending a workpiece.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bending punch 3, 3 'Work 4, 5 Protective sheet 6 Pressure sensor

Claims (3)

(57) [Claims] 1. A work and a protection sheet are superposed, bent so that the total thickness of the work and the protection sheet is substantially the same, and the protection sheet is supplied and wound from a direction perpendicular to a bending line of the work. Characteristic method of bending coated steel sheet. 2. The method for bending a coated steel sheet according to claim 1, wherein the surface pressure during the bending is measured, and the bending is performed at a pressure not exceeding the withstand pressure of the protective sheet or the coating film. Bending method for painted steel plate. 3. The method for bending a coated steel sheet according to claim 1, wherein a protective sheet is overlapped and bent on an outer surface of the work.