JPH07236970A - Production of metallic bathtub - Google Patents

Abstract

PURPOSE:To reduce the processing cost by improving a welding method of a drum part and a bottom part of a metallic bathtub. CONSTITUTION:In welding of a drum part 2 and a bottom part 3 of a metallic bathtub, a stepped part 2c which bends outside and projects is installed on a lower periphery of the cylinder tube like drum part 2. A standing periphery 3a of outer circumference of the bottom part 3 formed with pressing is inserted inside this stepped part 2c, and welding is executed from a corner surface 2d of this stepped part 2c. In such a way, exact welding can be easily executed without need for improving the machining precision.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a metal bathtub such as a stainless steel bathtub, and more particularly to improving a method for welding a body portion and a bottom portion of a bathtub.

[0002]

5 and 6 show an example of a conventional method for manufacturing a metal bath. In the figure, 1 is a flange part of a bathtub, 2 is a body part, 3 is a bottom part, 4 is an inner jig, and 5 and 6 are shown.
Is an outer jig, and 7 is a welding torch. In the conventional manufacturing method, a metal plate is pressed to form the flange portion 1 and the bottom surface portion 3, and the separately formed body portion 2 is joined by seam welding, argon arc welding or the like to form a bath. .

[0003]

However, in the conventional manufacturing method, when the lower edge 2a of the body portion 2 and the rising edge 3a of the outer periphery of the bottom surface portion 3 are butted and welded to each other, the difference in the circumferential length between the two causes If a step α as shown in 5 or a gap β is formed between the abutting end faces, there is a problem that cracks, pores, welding defects such as poor penetration are likely to occur after welding.

Further, due to welding heat generated when the lower edge 2a of the body portion 2 and the rising edge 3a of the bottom surface portion 3 are welded to each other, the rising edge 3a of the bottom surface portion 3 is released from permanent strain due to press working, and goes outward. As a result of the thermal strain that spreads, there is a problem that a step and a gap with the lower edge 2a of the body portion 2 are further increased.

Further, since the above-mentioned welding is butt welding, a high accuracy of the welding track is required to ensure this welding. Further, in order to stabilize the welding trajectory and further eliminate the steps and gaps, the lower edge 2a of the body portion 2 and the rising edge 3a of the bottom surface portion 3 must be processed by precision grinding or the like. There was a problem in that the cost would increase accordingly.

[0006]

In order to solve the above-mentioned problems, in the present invention, when welding the body and the bottom of a metal bath, the outer edge of the cylindrical body is bent to the outside. A protruding step portion is provided, and a rising edge of the press-molded outer periphery of the bottom surface portion is inserted inside the step portion and welded from the corner surface of the step portion.

Further, an inner jig having a concave portion at a position facing the welded portion is applied to the inside of the lower edge of the body portion, and a bottom surface is provided between the inner jig and the step portion of the lower edge of the body portion. Insert the rising edge of the outer periphery of the part, apply outer jigs to the upper and lower outer sides of the welded part, respectively, to supply the inert gas into the concave part of the inner jig, and from the corner surface of the step part. Argon arc welding.

[0008]

As described above, in the present invention, the step portion is provided at the lower edge of the body portion, and the rising edge of the outer periphery of the bottom surface portion is inserted inside the step portion to weld from the corner surface of the step portion. As a result, the accuracy required to eliminate the gaps required in the past and the accuracy of the circumference of the weld are no longer required, and the accuracy of the welding track can be lower than before, which reduces the processing cost. To be

Further, due to the influence of heat due to welding, the step portion of the body portion causes thermal strain to the inside, and the rising edge of the bottom portion causes thermal strain to the outside. Therefore, the thermal strain of the both causes the step portion and the rising edge. Will strongly press-bond each other, which will have a favorable effect on welding. Therefore, according to the present invention, it is possible to obtain an effect that the tightening force of the inner and outer jigs can be reduced and a jig having a lower rigidity than the conventional jig can be used.

[0010]

Embodiments of the present invention will be described below with reference to FIGS. In the figure, the same symbols as the above-mentioned symbols indicate the same items. That is, in the figure, 1 is a flange portion of a bathtub, 2 is a body portion, 2b is a bent edge portion at an upper edge, and the flange portion 1 is superposed on the bent edge portion 2b and fixed by welding. There is. 3 is a bottom portion formed by press working, 3a
Is the rising edge of its outer circumference.

In this embodiment, a step portion 2c is formed at the lower edge of the body portion 2 so as to be bent outward and protrude outward by about the thickness of the plate. Inside the step portion 2c, a press-molded bottom portion is formed. The rising edge 3a of the outer periphery of 3 is inserted, and welding is performed by the welding torch 7 from the corner surface 2d of the stepped portion 2c.

More specifically, a frame-shaped inner jig 4 having a recess 4c at a position facing the welded portion is applied to the inner side of the lower edge of the body 2 having the step 2c. ,
Between the inner jig 4 and the inside of the step 2c at the lower edge of the body 2,
The rising edge 3a on the outer periphery of the bottom surface portion 3 is inserted, and frame-shaped outer jigs 5 and 6 are applied to the upper and lower outer sides of the welded portion, respectively. An inert gas is supplied, and argon arc welding is performed by the welding torch 7 from the corner surface 2d of the stepped portion 2c.

When welded as described above, the circle A in FIG.
Since the inside is almost molten, the gap a as shown in FIG.
Even if there are gaps or gaps b, these gaps are filled with the molten metal.

Further, when the fitting portion between the step portion 2c and the rising edge 3a is welded, the step portion 2c is distorted inward and the rising edge 3a is distorted outward due to the heat effect thereof. As a result, the step portion is distorted. The 2c and the rising edge 3a are pressure-bonded to each other, which has a favorable effect on welding.

[0015]

As described above, in the present invention, the body portion 2
Since a step portion 2c is provided on the lower edge of the step portion, and a rising edge 3a on the outer periphery of the bottom surface portion 3 is inserted inside the step portion 2c to weld from the corner surface 2d of the step portion, this is conventionally required. Since the accuracy for eliminating the gap and the accuracy of the circumferential length of the welded portion are not required, and the accuracy of the welding track may be lower than the conventional one, the present invention has an effect of reducing the processing cost.

Further, due to the influence of heat generated by welding, the body 2
Since the stepped portion 2c causes thermal strain to the inside and the rising edge 3a of the bottom surface portion 3 causes thermal strain to the outside, the stepped portion 2c and the rising edge 3a should be strongly pressure-bonded to each other due to the thermal strain of both. It will have a positive effect on welding. Therefore, according to the present invention, it is possible to obtain an effect that the tightening force of the inner and outer jigs can be reduced and a jig having a lower rigidity than the conventional jig can be used.

[Brief description of drawings]

FIG. 1 is a perspective view showing a metal bathtub before connection according to the present invention.

FIG. 2 is an elevational view showing a partial cross-section of a method of welding a body portion and a bottom portion.

FIG. 3 is a vertical sectional view of a welded portion.

FIG. 4 is an explanatory view of the action of a welded portion.

FIG. 5 is a vertical sectional view showing a state of a conventional metal bath before welding.

FIG. 6 is a partial cross-sectional view showing a conventional welding method.

[Explanation of symbols]

 1 Flange part of bathtub 2 Body part 2a Lower edge 2b Bending edge part 2c Step part 2d Corner face 3 Bottom part 3a Rising edge 4 Inner jig 4a Recess 5,6 Outer jig 7 Welding torch

Claims (2)

[Claims] 1. In welding of a body and a bottom of a metal bathtub, a step portion is provided at a lower edge of a cylindrical body portion so as to be bent outward, and a step is formed inside the step portion. A method for manufacturing a metal bath, wherein a rising edge on the outer periphery of the bottom surface portion is inserted and welding is performed from the corner surface of the step portion. 2. An inner jig having a recess provided at a position facing the welded portion is applied to the inner side of the lower edge of the body portion according to claim 1, and the inner jig and the inner side of the step portion of the lower edge of the body portion. In between, the rising edges of the outer periphery of the bottom surface portion are inserted, and outer jigs are applied to the upper and lower outer sides of the welded portion, respectively, to supply an inert gas into the concave portion of the inner jig, A method for manufacturing a metal bathtub, characterized in that argon arc welding is performed from the corner surface.