JPH07214319A - Welding method for sheet metal small hole - Google Patents

Abstract

(57) [Summary] [Structure] Welding torch 7 and triaxial insert roller 1
By installing the device equipped with 4 in the small diameter hole of the welded part, the joint accuracy before welding and the target position of the arc point are secured and automatic welding is performed. [Effect] It is possible to sufficiently improve the quality, performance, and economical efficiency of the plate heat exchanger that is permanently joined.

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 large-sized plate-type heat exchanger permanently welded and joined.

[0002]

2. Description of the Related Art A plate-type heat exchanger is configured such that a plurality of corrugated heat transfer plates are stacked and the heat exchange medium liquid is passed through a liquid passage hole from an inlet / outlet port of an introduction pipe provided on an outer heat transfer plate. By causing the heat transfer plates to flow so as to face each other, heat is exchanged between the two media.

Conventionally, the heat transfer plates are connected to each other by JP-A-56-8779.
As disclosed in Japanese Patent Laid-Open No. 7-71894 and Japanese Patent Laid-Open No. 60-71894, the outer peripheral portion of the heat transfer plate and the liquid passage hole portion are joined to each other by welding, brazing, and gaskets and bolts. Various methods such as tightening are adopted.

[0004]

Among the various plate type heat exchangers, permanent ones are of the welding and brazing type. Of these, the welding type is one of the plate type heat exchangers. The inner peripheral portion is joined. Further, this work is a work in which stacking and welding are alternately repeated for each sheet, and particularly in the latter welding of the inner peripheral portion of the liquid passage hole, it is a narrowing work in which the space of the stacking portion is small and the inner diameter of the hole is small. For this reason, we were forced to weld in a state where no measures were taken,
From the viewpoint of welding quality, heat deformation occurs due to welding heat input, and melting and burnout frequently occur. The quality deteriorates, and when repair work is impossible, the heat exchanger is also scrapped.

It is an object of the present invention to provide a welding method and welding apparatus for welding a liquid passage hole portion to obtain sufficiently good welding quality even in a narrow space of a thin plate structure.

[0006]

In order to achieve the above object, the present invention is based on the inner peripheral end of the liquid passage hole (that is, the line to be welded) with two thin plates superposed on each other, and the welding heat input is applied. Even if this happens, the overlapped portion is always brought into close contact with each other to form a combined joint portion, which enables welding work. At the same time, the welding method and welding equipment for small-diameter small-diameter holes are constructed so that the welding torch can be positioned and the welding work can be performed while the arc point always matches the welding line.

[0007]

The center of the liquid passage hole is positioned by arranging and rotating a supporting device having three sets of pinching rollers at the same interval at the inner peripheral end of the liquid passage hole. Further, when the tapered inner groove provided on the outer peripheral portion of each sandwiching roller is attached by slightly pressing the inner peripheral end of the liquid passage hole formed of two thin plates,
Due to the wedge action of the inner groove, the same thin plates are overlapped with each other and good adhesion is obtained, so that welding defects such as melting and melting do not occur.

In this state, by positioning and holding the welding torch integrated with the supporting device, the arc point can always be accurately aimed at the line to be welded. Further, the sandwiching roller not only corrects the welding heat deformation, but also absorbs the welding heat and contributes to the prevention of the burn-through at the inner peripheral end portion.

[0009]

An embodiment of the present invention will be described below with reference to the drawings. First, FIG. 3 is a top view of the plate heat exchanger,
A heat transfer plate 1 formed by press molding into a corrugated shape is composed of a liquid passage hole 2 as a passage port for a heat exchange medium liquid and a liquid introduction pipe 3 as a medium liquid inlet / outlet port. FIG. 4 shows the image of FIG.
A cross-sectional view of the central part of the heat exchanger viewed from the a'-side is shown, in which a plurality of heat transfer plates 1 are laminated, and an outer peripheral part 5 is welded all around with a spacer 4 sandwiched between each laminated part and a container for heat exchange. Is formed.
Then, in the container, heat exchange is performed by the medium liquids A and B, which are different from each other on the front surface side and the back surface side of the heat transfer plate 1, flowing opposite to each other. FIG. 5 is a sectional view of the liquid passage hole 2 and the liquid introducing pipe 3 viewed from the surface of FIG.
The inner peripheral end portion 6 of the liquid passage hole 2 forms an inflow passage for the A liquid and the B liquid, so that the heat transfer plates 1b and 2a (A liquid passage), 2
a and 2b (B liquid passage) and thereafter 2b and 3a (A liquid passage), 3
The inner peripheral end portion 6 is welded by overlapping with a and 3b (liquid passage B).

When the outer peripheral portion 5 of the heat transfer plate and the inner peripheral portion 6 of the liquid passage hole are welded, assuming that all the heat transfer plates are laminated and then welded together, the former is possible, but the latter is It is almost impossible because the welding torch is inserted to the tip of the liquid passage hole for narrow welding. Therefore, it is necessary to perform welding each time the heat transfer plates are laminated, and it is extremely important to accurately adhere to the two heat transfer plates in the welded part and to accurately position the arc transfer point while maintaining this state.

Next, FIG. 1 is a main portion of the present invention, showing a small diameter hole welding apparatus for welding the inner peripheral end of the liquid passage hole 2, and a sectional view taken along the line ??? Shown when positioning <A> and when opening <B>.

As an example, a TIG welding torch 7 is installed on the inner peripheral end portion 6 of the liquid passage hole which becomes the welded line. The welding torch 7 is supported by a torch holder 10 from a column 8 via a slide base 9 for position adjustment. Also support 8
From the above, a support plate 12 is attached via an arm 11, and three sets of rotatable rollers 14 are arranged via a shaft 13 at positions where the circumference is divided into three at equal intervals. Further, the roller 14 is provided with a V-shaped inner groove at the center thereof over the entire circumference. Further, the shaft 1 is provided between the support plate 12 and the roller 14.
Clamp plate 15 is arranged through 3 and clamp plate 1
A clamp arm 16 for rotating operation is provided at the tip of 5. It should be noted that the clamp plate 15 and the support plate 12 through which the shaft 13 passes are provided with long grooves for sliding, respectively, so that the three sets of the pinching rollers 14 can simultaneously move in the inner peripheral end portion 6 direction.

Next, the operation will be described. First, the column 8 is positioned at a predetermined position of the inner peripheral end portion 6 which is the welded portion (the positioning mechanism is not shown). Clamp arm 16
(Fig. 2 <B>) with three open rollers 14
Has a slight distance from the inner peripheral end 6. Here, when the clamp arm 16 is rotated clockwise in the figure (FIG. 2A), the long groove of the clamp plate 15 causes the support plate 1 to move.
The shaft 13 in the long groove of 2 is pushed outward, that is, the pinching roller 14 provided on the shaft is abutted against the inner peripheral end portion 6, and as a result, two heat transfer plates 1b and 2a, 2a and 2b, etc. The central V-shaped groove of the sandwiching roller is bite-positioned at the inner peripheral end of the liquid passage hole constituted by, and a joint joint having no gap before welding can be prepared. Further, the aiming position of the welding torch 7 to the proper arc point can always be kept at the center position by the action of the three sets of the sandwiching rollers, and the welding work can be performed under proper conditions.

The welding method and welding apparatus of the present invention are not limited to the welding of the inner peripheral edge of a thin plate small diameter hole of a heat exchanger, and can be sufficiently used for welding joints of small diameter holes even in general welded structures. It is also possible to do so.

[0015]

Since the present invention is configured as described above, it has the following effects.

(1) When welding a small-diameter inner peripheral portion, the welding work can be performed while the welded portion is previously held in a close contact state.

(2) The welding operation can be performed while the center is always positioned by the action of the three pairs of pinching rollers.

(3) The pinching roller that comes into contact with the portion to be welded absorbs the heat input to the welding and thus helps prevent deformation of the welding.

(4) The welding method and welding apparatus of the present invention can be applied to welding of various small-diameter holes.

(5) Due to the actions of (1) to (5), it is easy to automate the welding of the inner peripheral portion of the small diameter hole, which is extremely difficult, and the quality of the welded portion is further improved. You can get a good product.

[Brief description of drawings]

FIG. 1 is a side view of a small diameter hole welding apparatus which is a main part of the present invention.

FIG. 2 is an explanatory diagram of an operation viewed from the side of the line of FIG.

FIG. 3 is a top view of a heat exchanger heat transfer plate.

FIG. 4 is a cross-sectional view taken along the line EE ′ of FIG.

FIG. 5 is a cross-sectional view as seen from the surface of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Heat transfer plate, 2 ... Liquid passage hole, 6 ... Inner peripheral end part, 7 ... Welding torch, 12 ... Support plate, 13 ... Shaft, 14 ... Crawler roller, 15 ... Clamp plate.

Claims (1)

[Claims] 1. A plate type heat exchanger comprising a plurality of heat transfer plates press-formed in a corrugated shape, which are joined to each other around the periphery and the liquid passage holes. In the welding of the small diameter hole portion for liquid passages composed of a thin plate heat transfer plate, it is possible to perform welding while accurately positioning the welding torch with respect to the welded line while always forming a united joint by closely adhering the overlapping portion. Welding method for small diameter holes in thin plates.