JP5417349B2 - Thin plate member welding method and can manufacturing method using the welding method - Google Patents

Description

  The present invention relates to a method for welding thin plate members and a method for manufacturing a can body using the welding method.

When welding metal plates, the quality of the welded portion depends on conditions such as the method of holding the welded portion, the positional relationship between the welding members and the heating torch, and the amount of heat input to the welded portion. This condition becomes more strict as the thickness of the metal to be welded becomes thinner.
For example, a hot water storage water heater that has been popular in recent years is equipped with a large-capacity metal hot water storage tank to store boiling water, but the structure of the can body of the hot water storage tank is generally In this case, a can body is formed by welding a bowl-shaped part called an end plate on the top and bottom of a cylindrical part called a body. As for the circumferential welded portion, various types of joints and welding methods have been studied so far (for example, Patent Document 1).
However, in these methods, a gap is generated in the circumferential welded portion, stress concentration occurs, and depending on the liquid to be stored, a gap corrosion occurs. For this reason, in order to prolong the life of the can body, it is desirable to use a butt joint having no gap. In general, butt welding of thin plates provides a good butt joint if the gap between the joints and the displacement in the thickness direction (difference, that is, displacement in the thickness direction of the two plates) are not strictly controlled. I can't. Therefore, the vicinity of the weld is restrained from both sides with a jig or the like to realize a butt joint (for example, Patent Document 2), or the shape of the joint is devised to obtain a bead shape equivalent to butt welding (for example, Patent Document 3). ).

JP 2007-009290 A JP 2002-263835 A Japanese Patent No. 2593233

  However, the warm water container shown in Patent Document 1 has a barrel and two mirrors, and adopts a structure in which the ends of both mirrors are inserted into the barrel and welded from the outside. A welding gap is formed. If water containing chlorine ions enters the weld gap, there is a problem that crevice corrosion occurs due to the local battery action, shortening the service life, and stress tends to concentrate on the tip of the gap. There is also a problem that fatigue failure due to fluctuations in internal pressure of the body is likely to occur.

In order to solve the above problems, it is desirable to use a butt joint having no gap. The above-mentioned Patent Document 2 shows a can body in which butt welding is performed, and a cylindrical body and an end plate are butt welded from the inside over the entire circumference.
However, in this structure, it is necessary to minimize the above-described misunderstandings and gaps in the butt weld portion during welding work, and in order to maintain a constant positional relationship between the cylindrical body and the end face of the end plate, A restraining jig from both the inside and the outside is required. For this reason, it is necessary to provide a large opening on the top of the can that is not necessary for the function, and because welding is performed from the inside, a large dedicated tool is required for holding and rotating the torch, resulting in workability. However, there is a problem that the manufacturing cost is high.

  Patent Document 3 discloses a technique in which a cover plate having a tapered portion is pressed against a body and welding is performed so that the tapered portion is melted. However, in this method, the relative position between the body and the lid is maintained only by the friction at the contact portion between the tapered portion and the edge of the body, and the mechanism for managing the gap of the welded portion and the restraint in the plate thickness direction. There is no. For this reason, if the lid deforms radially outside or the fuselage inward due to local dimensional variations in the fuselage or lid and thermal deformation during welding, the welded joint does not come into contact with the gap, resulting in a gap. There is a problem that welding becomes difficult.

  The present invention has been made to solve the above-described problems, and is formed by welding thin plates, for example, in a can body of a hot water storage type hot water heater, a thin plate of a body portion and an end plate portion constituting the can body The purpose of this invention is to obtain a weld bead shape having no stress concentration portion equivalent to butt welding by preventing the occurrence of gaps and misunderstandings in the welded portion without requiring a restraining jig with a dedicated tool for welding.

  1st invention is a welding method of the 1st thin plate member and the 2nd thin plate member, Comprising: The L-shaped end part is provided in the end of the said 1st thin plate member, The 2nd thin plate member An L-shaped end portion having an eaves portion is provided at one end of each of the first and second thin plate members. The eaves portion of the second thin plate member provided is extended in the direction in which the contact surface exists, the contact surfaces of the first and second thin plate members are in contact, and the eave portion is the first thin plate member. After the butt portion is formed so as to cover the top of the L-shaped end with a predetermined gap, the butt portion is melted by heating.

  According to a second aspect of the present invention, the first thin plate member is either a body part or a body part, and the second thin plate member is either a body part or a body part, and the can according to the first invention is used. It is a manufacturing method.

  Since the first invention employs the welding method as described above, even if there is a mistake in the first and second thin plate members, the top of the L-shaped end of the first thin plate member and the second It is possible to adjust the installation position along the contact surface by the dimension of the predetermined gap with the eaves of the thin plate member, and to correct the mistake, and no special dedicated tool is required, reducing the manufacturing cost. Peeled off. Further, by appropriately setting the dimensions of the L-shaped end portion and the eave portion, a weld bead shape equivalent to butt welding can be obtained, and there is an effect that there is no risk of stress concentration.

It is a figure which shows the joint structure of the welding part by Embodiment 1. FIG. It is a figure which shows the welding result by Embodiment 1. FIG. FIG. 6 is a diagram illustrating a method for manufacturing a hot water storage tank can according to a second embodiment.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to the drawings.
FIG. 1 is a cross-sectional view showing a first thin plate member 1 and a butted portion 20 of a second thin plate member 2 in the thin plate member welding method according to the first embodiment. The first end of the thin plate member 1, L-shaped end portion 1a is formed in the bending angle theta ₁ rising to a height H1. The rising bending angle theta ₁ is obtuse. With L-shaped end portion 2a is formed on the rising bending angle theta ₂ having a height H2 for the second end of the thin plate member 2, the contact surface 2c, which will be described later with integrated from the L-shaped end portion 2a The eaves part 2b extended | stretched in the direction where this exists is provided. The length of the eaves portion 2b is L, and the rising bending angle theta ₂ is an acute angle. The height H2 of the L-shaped end portion 2a of the second thin plate member 2 is between the top portion 1b of the L-shaped end portion 1a of the first thin plate member 1 and the eaves portion 2b of the second thin plate member 2. Is set to have a gap G.

The material of the first thin plate member 1 and the second thin plate member 2 is ferritic stainless steel, but may be austenitic stainless steel or general mild steel, and is not particularly limited.
The plate thickness t of the first and second thin plate members 1 and 2 is 0.5 mm to 2 mm, and the height H1 of the L-shaped end 1a of the first thin plate member 1 is 2 to 5 times the plate thickness t. The length L of the eaves portion 2b of the second thin plate member 2 is about 2 to 4 times the plate thickness t. Further, the gap G is provided as about 0.2 mm.

The contact surface 1c of the L-shaped end portion 1a of the first thin plate member 1 and the contact surface 2c of the L-shaped end portion 2a of the second thin plate member 2 are pressed against each other to be in contact with each other. Form. In this state, the torch 4 is heated to melt the entire butt 20. TIG welding is used for heating, but is not limited to this. In such welded joints where the configuration according to the first embodiment, the first L-shaped end portion 1a of the thin plate member 1 rises at an obtuse bending angle theta ₁ with the second L-shaped end of the thin plate member 2 since part 2a is formed on the rising bending angle theta ₂ at an acute angle, first, as a set slightly eye difference when the second sheet metal members 1 and 2 occurs, the contact surfaces 1c, 2c and the contact state One or both of the thin plate members can be slid and moved while maintaining the position, and an adjustment function is provided so as to reduce misunderstandings.

  After TIG welding is performed, a bead 7 equivalent to butt welding is obtained as shown in FIG. The bead wall thickness W is substantially the same as the thickness t of the first and second thin plate members 1 and 2, and a complete penetration shape is formed with less possibility of stress concentration at the bead base 7a. In order to obtain such a bead thickness W and its length WL, the heights H1 and H2 of the L-shaped end portions 1a and 2a shown in FIG. 1 and the length L of the eaves portion 2b are appropriately selected. Is achieved.

Further, even when the thin plate members 1 and 2 are distorted by heat input during welding, the thin plate members 1 and 2 are restrained by the L-shaped end portions 1a and 2a as long as both members are pressed by a tool or the like. The relative positional relationship of is not changed.
As described above, according to the first embodiment, it is possible to prevent the occurrence of a gap between the contact surfaces 1c and 2c of the abutting portion 20 of the thin plate members 1 and 2 during welding, and to reduce mistakes. It does not require parts or special dedicated tools, is inexpensive, can perform stable welding with improved heat input effect, and can obtain a beat shape equivalent to butt welding.

Embodiment 2. FIG.
Next, the manufacturing method of the can body by Embodiment 2 is demonstrated based on figures.
FIG. 3 is a cross-sectional view showing a method for manufacturing a metal hot water storage tank of a hot water storage type water heater that is a can 30 according to the second embodiment. A body portion 8 having an L-shaped end portion 8a similar to the second thin plate member 2 of the first embodiment described above on both end faces of the cylinder, and an eaves portion 8b extending to the end portion 8a. End plates 9 are provided at both ends. An L-shaped end portion 9 a similar to the first thin plate member 1 of the first embodiment described above is formed at a portion of the end plate portion 9 that is coupled to the body portion 8.
After the eaves portion 8b of the body portion 8 is combined so as to cover the top portion 9b of the L-shaped end portion 9a of the end plate portion 9, the contact surface 8c of the L-shaped end portion 8a, as in the first embodiment, The abutting portion 20 is formed so that the contact surface 9c of the L-shaped end portion 9a contacts each other, and the contact surfaces 8c and 9c are in close contact with each other using the jig 10 from the outside of the end plate portion 9. Then, TIG welding is performed from above the butt portion 20 as in the first embodiment.

  Since the can 30 is manufactured by such a method, the heat input by the torch 4 can be achieved, and the butt portion 20 can be melted more completely. In addition, a hot water storage tank having high dimensional accuracy with little variation in the overall length of the hot water storage tank, which is the completed can body 30, can be manufactured at low cost through a simple production process. Further, since the welded portion is formed by complete penetration, crevice corrosion and stress of the welded portion in a product such as a hot water storage tank which is the can body 30 where the temperature cycle is applied or a repeated stress is generated. Durability without concentration is improved, and a long-life can 30 can be manufactured.

The can 30 of the second embodiment has an inner diameter of 200 mm to 700 mm, a total length of 1 m to 2 m, and a plate thickness of about 1 mm. Moreover, although this can 30 showed the example applied to a hot water storage tank, it is not limited to hot water, What is necessary is just various liquids.
Furthermore, when the method of applying pressure from the outside of the end plate portion 9 described in the second embodiment is also applied so as to press from both ends of the thin plate members 1 and 2 in the first embodiment, a better quality welded portion can be obtained.
Moreover, although the edge part of the trunk | drum 8 shall have the eaves part 8b, you may mutually replace the end part structure of the end plate part 9 and the trunk | drum 8. FIG.

1 1st thin plate member, 1a L-shaped end part, 1b top part, 1c contact surface,
2 second thin plate member, 2a L-shaped end, 2b eaves part, 2c contact surface, 8 body part,
8a L-shaped end, 8b eaves, 8c contact surface, 9 end plate, 9a L-shaped end,
9b top part, 9c contact surface, 20 butting parts, 30 can body,
θ ₁ , θ ₂ rising bending angle.

Claims (4)

A welding method for a first thin plate member and a second thin plate member, wherein an L-shaped end is provided at one end of the first thin plate member, and an eaves is provided at one end of the second thin plate member. An L-shaped end having a portion is provided,
Each of the L-shaped end portions of the first and second thin plate members is provided with a contact surface where the L-shaped end portions contact each other, and the eaves portion of the second thin plate member is the contact surface. The contact surfaces of the first and second thin plate members are in contact with each other, and the eaves portion is in contact with the top of the L-shaped end portion of the first thin plate member. A method of welding a thin plate member, wherein the butted portion is melted by heating after the butted portion is formed so as to cover the gap. The L-shaped end portion of the first thin plate member is formed to be raised at an obtuse angle, and the L-shaped end portion of the second thin plate member is formed to be raised at an acute angle. The thin plate member welding method according to claim 1. The contact surface of the L-shaped end portion of the first and second thin plate members is pressed and melted so as to be in close contact with each other. Thin plate member welding method. A can body manufacturing method for manufacturing a can body by welding end portions of a body portion and an end plate portion, wherein the first thin plate member is either the body portion or the end plate portion, and the second The manufacturing method of the can characterized by using the thin plate welding method of any one of the said Claims 1-3 which made the thin plate member either the said end plate part or the said trunk | drum part.

Images