US2384324A

US2384324A - Method of making hot-water tanks

Info

Publication number: US2384324A
Application number: US431042A
Authority: US
Inventors: Wesley G Martin
Original assignee: AO Smith Corp
Current assignee: AO Smith Corp
Priority date: 1942-02-16
Filing date: 1942-02-16
Publication date: 1945-09-04
Anticipated expiration: 1962-09-04

Description

Sept. 4, 1945.

W. G. MARTIN METHOD OF MAKING HOT WATER TANKS Filed Feb. 16, 1942 ATTORNEY.

atente Sept. 4, M45

T PATENT QFFICE METHOD OF MAKING HOT-WATER TANKS Application February 16, 1942, Serial No. 431,042

Claims.

This invention relates to a method of making a hot water storage tank and more particularly to the method of making a hot water storage tank which is lined with fused ceramic enamel or other corrosion resistant protective material, such as galvanizing, to protect the tank from injury by corrosion while in use.

One object of the present invention is to provide a method of making a tight fitting joint between the head and shell of a hot water storage tank.

Another object is to provide a method of constructing a lined hot water tank in which the joints between the heads and shell are strong and durable, and not subject to undesirable deflection stresses in service.

Other objects of the invention will appar in the following description of an embodiment of the invention illustrated in the accompanying drawing.

In the drawing:

Figure 1 is a longitudinal section of the completed hot water tank constructed according to the method of the invention;

Fig. 2 is a longitudinal section of a shell and a punch and die applied thereto for sizing the shell;

Fig. 3 is a perspective view of a head of a hot water tank, showing the supporting member on which the head rests during the fusing of the ceramic lining to the head;

Fig. 4 is a. longitudinal sectional view of a head and shell of a hot water tank showing their position with respect to each other just prior to assembly and also showing in similar section the jigs for holding and sizing the head and shell during their assembly; and

Fig. 5 is an enlarged longitudinal section through a completed joint.

In constructing a hot water tank in accordance with the invention, the shell I is first fabricated by rolling or otherwise forming a suitable metal blank into a cylinder and then welding the cylinder along its longitudinally extending seam.

The metal blank employed is of a steel that has substantially uniform residual stresses to thereby eliminate extensive warping when heated. The longitudinal welding of the seam of the cylinder is performed with considerable care to obtain an accurately'dimensioned circumference for the shell.

Upon completion of the shell I as described, the end sections 2 of the shell are subjected to a sizing operation in a. device such as the punch and die 3, to true-up the ends of the shell into a substantially cylindrical shape. This sizing operation should leave th respective ends of the shell with their circumference and diameter dimensionally accurate in order to properly receive the heads l and 5.

Th heads 4 .and 5 are fabricated in accurate dies from blanks of metal of a relatively heavier gauge than that employed in making the shell I. Any residual stresses therein are substantially uniformly distributed so that ther is less tendency for warping when heated to fuse the lining thereon.

The heads are made from the blanks described, by forming them preferably with convex crowns 6 and vertically flanged skirts I. In the forming operation the skirts l are fabricated with an outside diameter only sufilciently less than that of the inside diameter of the shell to permit insertion of the heads within the respective ends of the shell I, having regard to the thickness of the enamel. To obtain a tight fit between these members the dimensional tolerance limits of the heads and shell are maintained at a minimum.

After the construction of the shell I and the

heads

4 and 5 has been completed as described, ceramic enameling material is applied to their respective interior surfaces, including the surfaces of the flanged skirts I of the heads, and fused in place to form the lining 8. The lining 8 protects the interior surfaces of the heads and shell from corrosion by fluid contained in the tank in service.

The fusing of the ceramic enamel lining 8 to the interior of the shell I is accomplished by subjecting the shell to a heating operation in which the lining and shell are heated to about 1600 F. In this operation the shell is placed upright in a heating furnace. Th only portion of the furnace engaged by the shell is the floor or support contacted by the supporting end of the shell. This endwise vertical placement prevents any substantial sagging of the shell by the heat to which it-is subjected.

The fusing of the ceramic enamel to the

heads

4 and 5 is performed as in the case of the shell I, by subjecting the heads to a heating operation. The heads are specially supported in the heating furnace by a support member 9 that preferably contacts each respective head at four distinct points. The support member is formed generally in the shape of an X and each respective head is placed on an X support 9 in such a manner that the ceramic lining 8 faces upwardly and the ends of the flanges I engage the support member 9 at four circumferentially spaced points as illustrated in Fig. 3. In this position the crowns 6, constituting the bodies of the heads are suspended and held away from the supporting member 9 during the heating of the heads to fusing temperatures. This mode of supporting the heads prevents any substantial warping or deformation of them by the heat that is required to fuse the ceramic enamel lining 8 to their interior surfaces.

After the fusing operations for one or more coatings of enamel ar completed, the shell I and heads 4 and are inspected for possible defects in the lining 8. Since the assembly of the head 4 with the shell I .is preferably similar to that of the head 5 therewith, it is suflicient hereafter to limit the description to the assembly of the head 4 'with the shell I.

In assembling the members of the tank, the shell I is first placed within the jig III which preferably consists of two complementary members having semi-cylindrical openings to fit the shell, a illustrated in Fig. 4, and any quick operating mechanism, not shown, to close the members around the shell. The jig l0 holds the shell I circular and in alignment'with the head 4 as they are assembled together.

The head 4 is preferably held by the jig II, as illustrated in Fig. 4, the latter having means secured in a spud Or other suitable opening in the head for supporting and moving the head. The jig axially aligns the head 4 with the shell I and maintains this alignment during the assembly of the two members.

As the shell i and the head 4 are held in the jigs i0 and II respectively, as described, the head 4 is inserted in the end of the shell and subjected to axial pressure to obtain a tight fit between the flanged skirt 1 of the head and the end section 2 of the shell with the lining 8 of each member concentrically overlapping one another for a substantial distance and the edges of the shell and skirt flush. While the head and shell are held in this position the seam extending circumferentially around the edges of the shell and the skirt of the head is welded in any suitable manner, preferably by the electric arc method in which the metal of the respective edges of the ,members is melted and fused together.

It is preferred that the end of the head be disposed flush with the end of the shell as illustrated by Figs. 1 and 5. However, an angular seam may be provided between the head and shell by disposing'the head so that the end projects slightly outwardly from the end of the shell.

A close control of the dimensional tolerances of the head 4 and the shell I and the sizing and assembly of these members in the manner described provides a tight fit in the joint between the shell and head without requiring the use of a gasket. In the event that any liquid contained in the tank contacts exposed metal at th joint between the head and shell, the products of corrosion will quickly fill any space that may exist between the linings 8eof the skirt 1 of the head and the end section 2 of the shell to effectively prevent any further access of fluid to the Joint.

A similar function may also be performed by a thin corrosion resistant pliable material disposed in the joint between the overlapping parts of the head and shell.

The tanks made in accordance with the invention have strong and durable joints and the invention may readily be applied to the joining together of numerous kinds of liquid or fluid containers.

Various embodiments of the invention may be employed within the scope of the accompanying claims.

I claim:

1. In the manufacture and assembly of a hot water storage tank having a generally cylindrical shell and a head to close one end of said shell, the steps comprising sizing said shell to provide the same with an accurately determined internal circumference, lining the interior surface of the shell and head with a corrosion resistant material to protect the same from corrosion, thereafter applying a jig to the end of said shell to bring it into substantially circular section and holding it therein while inserting the head into the end of the shell with the end section of the head tightly fitting concentrically within and overlapping the end of the shell for a substantial distance, and circumferentially sealing the tank by welding the joint between the head and shell.

2. In the manufacture and assembly of a hot water storage tank having a generally cylindrical shell and a flanged head to close an end of sad shell, the steps comprising lining said shell and head with ceramic enameling material, heating the shell while supported on end to a fusing temperature for the enamel to bond the same to the wall of the shell, supporting said head on the end of its flange and heating the same to a fusing temperature for the enamel to bond the same to the wall of the head, thereafter applying a jig to the end of the shell to bring the same into more accurate circular shape for receiving the head, circumferentially aligning the shell and head while inserting the head into the end of the shell with the flange of the head tightly fltting concentrically within and overlapping the end of the shell for a substantial distance, and circumferentially sealing the tank by welding the .1 oint between the head and shell.

3. The method of making and assembling a hot water tank or like container, comprising forming a cylindrical shell from a sheet metal blank, welding the longitudinal meeting edges of the shell, subjecting the end portion of the shell to a cylindrical sizing operation to accurately determine the internal circumference thereof, forming an end head between accurately dimensioned dies to provide an end closure for said shell, said head having a substantially cylindrical circumferential flange with an outside circumference slightly less than the inside circumference of the end of said shell, lining said shell and said head with ceramic enameling material, heating the cylindrical shell while supported on end to a high temperature effecting fusing of the enameling material'and bond ng of the same to the wall of the shell, supporting said head on the edge of said flange and heating the same to a high temperature effecting fusion of the enameling material and bonding of the same to the head, applying a jig to the end of said shell to bring it into substantially circular section and holding it therein while inserting the head into the end of the shell with the flange on the head tightly fltting within the shell and having its edge extending in the direction of the end edge of the shell, the lining of the flange of the head overlapping the lining of the end of the shell in tight engagement for a substantial longitudinal distance, and circumferentially welding the edge portion of said flange and the end of the shell together to provide a joint withstanding the fluid pressure within the tank in service.

4. The method of making and assembling a hot water tank or like container, comprisng forming a cylindrical shell from a sheet metal blank, welding the longitudinal meeting edges of the shell, subjecting the end portion of the shell to a cylindrical sizing operation to accurately determine the circumference thereof, forming an end head between accurately dimensioned dies to provide an end closure for said shell, said head having a substantially cylindrical circumferential flange with an outside circumference slightly less than the inside circumference of the end of said shell, lining said shell and said head with ceramic enameling material, heating the cylindrical shell while supported on end to a high temperature eflecting fusing of the enameling material and bonding of the same to the wall of the shell, supporting said head on the edge of said flange and heating the same to a high temperature effecting fusion of the enameling material and bonding of the same to the head, applying a jig to the end of said shell to bring it into substantially circular section and holding it therein while inserting the head into the end of the shell with the flange on the head tightly fitting within the shell and having its edge extending in the direction of the end edge of the shell, the lining of the flange of the head overlapping the lining of the end of the shell in tight engagement for a substantial longitudinal distance, circumferentially welding the edge portion of said flan e and the end of the shell together to provide a joint withstanding the fluid pressure within the tank in service, and heating the end portion of the tank to fuse the enamel linings together adjacent the weld to protect the latter from corrosion.

5. The method of making and assembling a hot water tank or like container comprising forming acylindrical shell from a sheet metal blank, welding the longitudinal meeting edges of the .shell, subjecting the shell to a cylindrical sizing operation to accurately determine the circumference thereof, forming an end head between accurately dimensioned dies to provide an end closure for said shell, said head having a substantially cylindrical circumferential flange with an outside circumference slightly less than the inside circumference of the end of the shell, lining said shell and said head with ceramic enameling material, heating the cylindrical shell while supported on end to a high temperature effecting fusing of the enameling material and bonding of the same to the wall of the shell, supporting said head on the end of said flange and heating the same to a high temperature effecting fusion of the enameling material and bonding of the same to the head, circumferentially aligning the shell and head as the latter is inserted in one end or the shell with the enamel coatings in tight contact, and welding the adjacent edges together to provide a tightly fitting joint, the heat of the welding operation fusing together the linings of the head and shell adjacent the joint to protect the metal at the joint from corrosion.

WESLEY G. MARTIN.