JPH02122155A - Electric hot water heater - Google Patents

Abstract

PURPOSE:To make a drum satisfactory in weld quality and strength at negative pressure by radially expanding a shell plate at either or both of the upper and lower ends and by fitting the radially expanded parts on the respective rims of the upper and lower end plates and joining them by welding. CONSTITUTION:An electric heater for hot water has a drum 13 formed of an upper end plate 14, a lower end plate 15, and a shell plate 16 with the end plates fitted in the shell plate at the upper and lower ends. The upper end of the shell plate 16 is formed of a first tapering part 23, a second tapering part 24, and a radially expanded part 25. The outer circumferential surface 26 at the rim of the upper end plate 14 is inserted and fitted down the upper end part (the second tapering part 24 and the radially expanded part 25) of the shell plate 16 with the edge 27 of the end plate 14 pressed against the inner surface of the first tapering part 23 and their joint 28 welded from within the drum. The lower end of the shell plate 16 is formed of a tapering part 29 and a radially expanded part 30. The edge 31 of the radially expanded part 30 is pressed against the outer surface 32 of a tapering part of the lower end plate 15 and the joint 33 is welded from the outside of the drum. Even if drum parts show a lack of uniformity in the accuracy of forming, dimensional accuracy and circularity are secured for the brims of the upper and the lower end plates so that improvements can be achieved in weld quality and in strength at negative pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an electric water heater constructed of thin plate stainless steel, and more particularly to a can body thereof.

[Conventional technology]

In a conventional electric water heater using stainless steel, as shown in FIG. 6, a can body 4 is constructed by fitting a lower end plate 1, a lower end plate 2, and a body plate 8 at both upper and lower ends. Cold water is led into the can body 4 from the water supply pipe seat 5 attached to the lower head plate 2, heated by the electric heater 7 attached to the heater attachment port 6 arranged near the lower end of the body plate 8, and then transferred to the lower head plate l. Hot water flows out from the installed hot water pipe seat 8. 9 is a can leg mounting seat attached to the lower part of the body plate 8 using a d-joint or the like;
O is fixed with screws 11, etc. FIG. 7 is a detailed view of the fitting part between the upper end plate 1 and the body plate 3 in FIG. They are fitted so that the outer surfaces 8a of the wall portions abut against each other, and the abutting portions 3b are welded from the inside. FIG. 3 shows another conventional can body structure, which is similar in construction to that shown in FIG. 5, but the handling portion between the upper end plate 1' and the body plate 8' is different as shown in FIG. 9. That is, in FIG. 9, the peripheral end 1a/ of the upper mirror plate 1' is drawn in the centripetal direction, and the inner surface 3a/ of the upper end of the body plate 8' abuts against the outer end surface lb'. Butt part 8b'
Welded from the outside.

Each component of the above-mentioned can bodies Φ and 4' is made of stainless steel thin plates, and high dimensional accuracy is required in welding the thin plates. Generally, the head plate is formed by press working, which results in relatively high dimensional accuracy, but the body plate is made by bending a flat plate into a cylindrical shape and welding the joints, and it is usually around 1 m long. Because it is a thin plate, there will be variations in processing accuracy, the roundness including local deformation will be low, and dimensional accuracy will not be obtained.71. do not have. This gives rise to two problems. 1st
Furthermore, since it is difficult to ensure the fitting precision between the body plate and the end plate, there is a problem in that welding quality deteriorates due to variations in the blade P# fart when welded. Second, in general, in electric water heaters, negative pressure may occur inside the can due to a water outage or the like during use. In general, the buckling strength of a segmented shell against negative pressure is
It is said that if both ends (for electric water heaters, the fitting part between the upper and F side plates and the body plate) are strong enough to firmly maintain a perfect circle, but if there is some deformation, the resistance will decrease rapidly. There's a problem.

In addition, in the case of FA< Figures 8 and 9, the body plate 8' and the limit plate l'
is t-f) +T at the outer side 3b', so the inner side 8a
A gap] 2.12' is formed in the vicinity, which has the disadvantage of causing crevice corrosion. Gap 12 where special VC high temperature water always accumulates
It is easy to rot and grow.

[Problem to be solved by the invention]

The invention is intended to solve the above-mentioned problems, and its purpose is to provide a can structure that improves welding quality b) and 6) improves negative pressure strength.

[A way to solve the problem]

The present invention is constructed by expanding the diameter of one or both of the upper and lower ends of the body plate of the can body outward, and fitting and welding them to the circumferential ends of the upper and lower head plates to form a can body. do. Further, one or both of the heater attachment port and the can leg attachment seat are disposed on the body plate close to the enlarged diameter portion at the lower part of the body plate.

[Effect]

In the can body, the outer surface of the peripheral end of the upper end plate abuts against the inner end surface of the upper end of the body plate whose diameter has expanded outward.

Therefore, by expanding the diameter of the upper end of the body plate, the dimensions, cleanliness and roundness of the upper end can be ensured, and the processing accuracy is originally high.
By fitting with the peripheral edge of the upper mirror plate, dimensional accuracy during welding is improved and welding quality is improved. Furthermore, by improving the strong acidity of the i joint and ensuring roundness, the buckling strength during negative pressure can be improved.

The above-mentioned effect is exactly the same when the lower end of the steel plate is expanded and fitted and fitted with the peripheral end of the upper plate 'F.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail based on the drawings.

Figure g1 is a longitudinal sectional view of a can body 18 for an electric water heater according to an embodiment of the present invention, and the can body 18 is composed of a lower end plate 14, a lower end plate 15, and a body plate 16, which are fitted at both upper and lower ends. Cold water enters from a water supply pipe seat 17, is heated by a drowsiness heater 19 attached to a heater attachment port 18 disposed on one side of the body plate 16, and is turned into hot water and flows from a hot water supply pipe seat 20. Reference numeral 21 denotes a mounting seat for the can leg 22, which is attached to the lower part of the body plate by welding or the like.

In this embodiment, the body plate 18 is made of material with a thickness of 0.8 mm.
It is manufactured by roll bending a stainless steel plate of ~1.5 ff into a cylindrical shape and welding the joints by PIG welding or the like. After the body plate is made into a cylinder, the diameter of the upper and lower ends expands outward, and the diameter of the body plate is 14.15 mm.
The outer circumferential surface of the circumferential end is in a shape that abuts against each other.

On the other hand, the upper tax plate 14+ is formed by press-forming the same stainless steel plate as the plate 16 into a bowl shape, and the peripheral edge is cut off without any edges.

On the other hand, the sharp edge plate 15 is formed using the same material and processing method as the upper ruler plate 14, and has an inner diameter of 7″L1 at its circumferential end so as to abut against the inner surface of the lower end of the body plate 16.

Figure 2 shows the details of the fitting part for the above component numbers.
It is shown in Figure 3.

FIG. 2 shows a fitting portion between the lower mirror plate 14 and the body plate 16, and the upper end portion of the body plate 16 is formed by a first tapered portion 23, a second tapered portion 24, and an enlarged diameter portion 25. Upper mirror plate 1
The outer periphery 26 of the peripheral end of the body plate 16 is
．． 25, align the tip 27 with the inner surface of the first tapered part 28, and butt i! Weld l1SZ8 from inside the can. In this case, since the upper end of the body plate 16 is outwardly expanded in diameter, the upper end of the body plate 16, which is the fitting part with the upper end plate 14, has dimensional accuracy even if there are variations in processing accuracy. Since it is possible to ensure roundness and roundness, the fitting accuracy is good and the welding quality is improved.

FIG. 3 shows the fitting part between the upper mirror plate 15 and the body plate 16, and the lower end of the am plate 16 is formed with a tapered part 29 and an outwardly expanding diameter part 80. , the tip 4 of the enlarged diameter portion 80
81 is protruded from the outer surface 82 of the tapered part of the upper end plate 15;
Weld from the outside of the can body using abutment fJ33. The actions and effects regarding welding quality are the same as in the case of FIG. 2 described above.

The can body 18 manufactured as described above can provide a can body of excellent quality with improved processing accuracy of the welded portion, and at the same time, the negative pressure strength of the can body 18 is improved. In other words, when the magnetic water heater cannot be supplied with d1 water or frozen water, the # sprue (
If the hot water faucet (normally a hot water supply faucet) is lower than the installation position of the water heater, a negative pressure of around 0.51 g/cm will occur inside the can body 18, but the stainless steel can made of a thin plate of about 1 mm Securing the negative pressure strength is a major issue. In order to ensure negative pressure strength, it is necessary to maintain the roundness of the can body 18. An example of testing and pasting is 1.
The height is approximately 1500ag, and the body plate diameter is approximately 590mm, which is constructed by welding the upper and lower mirror plates of the same thickness to the body plate that has been appropriately reinforced with 4 mm 11.
In the base body of M, 6 welding part 83.2 in Fig. 2 and Fig. 8
8 is held with a perfect circular reinforcing plate, 0.8 kti/
There was a negative pressure intensity of cm2. However, if the reinforcing plate is removed, the weight decreases to 0.85 kg/cm2. The cause of the decrease is the roundness drop V due to twisting of the welded part 28.28
The parts are thick.

The present invention manages the dimensions of the circumferential ends of the upper and lower springboards.9 On the other hand, the upper and lower ends of the trunk board, which have irregularities due to machining and are out of roundness, are controlled at 25.80% in Figures 2 and 3. Since the fitting structure has an enlarged diameter as shown in the figure, roundness can be easily ensured and a decrease in negative pressure strength can be prevented.

In addition, the results of the negative pressure strength test indicate that the origin of the destruction of the body plate during negative pressure is due to the welding of the heater mounting port 18 and the can body GL mounting seat 21, which are required due to the construction of the electric water heater can body. It often occurs at sites where local deformation occurs due to deformation.

In the present invention, as shown in the detailed drawings of FIGS. 4 and 5, the above-mentioned portion where local deformation is likely to occur is disposed as close as possible to the enlarged diameter portion 80 at the lower end of the body plate 16. This can reduce local deformation.

Further, since the welding cap 28 in FIG. 2 is welded with a can-shaped concave weld, crevice corrosion will not occur on the water-contacted surfaces of the abutting portions.

In the above embodiment, the case where the diameter of both ends of the body plate is expanded is shown, but a part of the effect may be achieved by reducing the diameter inwardly. Similarly, the diameter of the circumferential end of the t-section springboard may be reduced inward. Furthermore, the materials of the valley components are not limited to the embodiments.

〔Effect of the invention〕

In the present invention, in which the upper and lower springboards and the upper and lower ends of the body plate are butted and welded to form a can body, the upper and lower ends of the body plate are enlarged in diameter (7), which causes variations in processing accuracy on the body. Even though
Since dimensional accuracy and roundness can be ensured at the peripheral ends of the upper and lower head plates, welding quality is improved and negative pressure strength is improved.

In addition, the heater attachment port and can body leg attachment seat, which are locally deformed, are placed close to the enlarged diameter portion at one end of the body plate, reducing deformation and improving negative pressure strength. Deterioration can be prevented.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a can body showing an embodiment of the present invention, and FIGS. 2 and 3 are enlarged sectional views showing details of the IJ contact portion. FIG. 4 is an installation diagram of the heater attachment port, and FIG. 5 is an enlarged view of the main parts showing the installation of the can body leg attachment seat. Figures 6 and 3 are longitudinal cross-sectional views of conventional stainless steel cans for 4-temperature water heaters, and Figures 7 and 9 are enlarged cross-sections showing details of the -f: welded parts. It is a diagram. 18... Can body 14... Upper end plate 15...
Lower part 10 - Mirror plate 16...Body plate 18...Heater mounting port 22...Can body leg mounting seat. RishinmijinrokuDushi￥S宕ba

Claims (1)

[Scope of Claims] 1. An electric appliance in which the upper and lower ends of the upper and lower head plates and the upper and lower ends of the body plate are abutted and welded to form a can body, characterized in that at least one of the upper and lower ends of the body plate is enlarged in diameter. Water heater. 2. The product described in claim 1, characterized in that the circumferential end of the upper end plate is abutted against the inner surface of the upper end of the body plate whose diameter has expanded outward, and the abutted portion of the two is welded from the inside. Electric water heater. 3. In the product described in claim 1, the circumferential end of the lower end plate is abutted against the inner surface of the lower end of the body plate whose diameter has expanded outward, and the abutted portion of the two is welded from the outside. Features: Electric water heater. 4. In the product described in claim 3, either the heater attachment port or the can leg attachment seat is disposed close to the expanded diameter portion of the lower end of the body plate whose diameter expands outward. An electric water heater featuring