WO2009006671A1

WO2009006671A1 - Method of forming a tank

Info

Publication number: WO2009006671A1
Application number: PCT/AU2008/000749
Authority: WO
Inventors: Richard James Aimers; Evan Albert Smith
Original assignee: Dux Manufacturing Limited
Priority date: 2007-07-11
Filing date: 2008-05-28
Publication date: 2009-01-15
Also published as: AU2008274879A1

Abstract

A method of forming a tank (30). The method comprising the steps of: providing a cylinder (24) having a cylinder wall (26) and a first end (28), providing a first end cap (10) having a peripheral edge portion (16), and forming the edge portion (16) of the end cap (10) to create a shoulder (20) and a peripheral skirt (22). The skirt (22) depends from the shoulder (20) and has a smaller outer diameter than the inside diameter of the cylinder wall (26). The method also includes arranging the skirt (22) of the end cap (10) within the cylinder (24) such that the shoulder (20) of the end cap (10) sits on the first end (28) of the cylinder (24) and the skirt (22) extends axially within the cylinder (24) and welding the skirt (22) to the cylinder (24).

Description

Method of Forming a Tank

Technical Field

The present invention relates to a method of forming a tank and in particular to a method of welding a dome end cap to an end of a cylinder of a tank.

Background of the Invention

In existing methods, hot water heater tanks are formed by enlarging the cylinder end sufficient to allow the dome to fit inside and using a fillet weld joint to join the dome to the cylinder end.

Using such existing methods, it is difficult to obtain a welded joint that passes fatigue testing to Australian Standard 1056. Tanks formed by such methods often suffer from failure at the weld joint during fatigue testing.

Object of the Invention

It is the object of the present invention to substantially overcome or at least ameliorate one or more of the disadvantages of the prior art, or to provide a useful alternative.

Summary of the Invention

Accordingly, in a first aspect, the present invention provides a method of forming a tank, said method comprising the steps of: providing a cylinder having a cylinder wall and a first end; providing a first end cap having a peripheral edge portion; forming the edge portion of the end cap to create a shoulder and a peripheral skirt, the skirt depending from the shoulder and having a smaller outer diameter than the inside diameter of the cylinder wall; arranging the skirt of the end cap within the cylinder such that the shoulder of the end cap sits on the first end of the cylinder and the skirt extends axially within the cylinder; and welding the skirt to the cylinder.

The steps of arranging the skirt in the cylinder and welding the skirt to the cylinder are preferably performed robotically. The step of forming the edge portion of the end cap is preferably performed by rolling. The step of welding the skirt to the cylinder is preferably performed by butt welding. Optionally, the method further comprises repeating each of the steps in respect of a second end of the cylinder and a respective second end cap. The method is preferably a method of forming a hot water heater tank.

In a second aspect, the present invention provides a tank comprising: a cylinder having a cylinder wall and a first end; and a first end cap having an edge portion, the edge portion having a shoulder and a peripheral skirt, depending from the shoulder, the skirt having a smaller outer diameter than the inside diameter of the cylinder wall, wherein the skirt is arranged within the cylinder such that the shoulder of the end cap sits on the first end of the cylinder and the skirt extends axially within and is welded to the cylinder.

The end cap is preferably substantially dome shaped. The tank preferably further comprises a second end and a second end cap, similar to the first end cap, the second end cap being arranged within and welded to the cylinder in the same way as the first end cap. The tank is preferably a hot water heater tank.

Brief Description of the Drawings

A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings wherein:

Fig. 1 depicts an end cap of a tank mounted in a rolling machine;

Fig. 2 depicts the end cap of Fig. 1 after being rolled;

Fig. 3 depicts the end cap of Fig. 2;

Fig. 4 depicts a cylinder of a tank and the end cap of Fig. 3; and

Fig. 5 depicts the cylinder and end cap of Fig. 4 assembled.

Detailed Description of the Preferred Embodiments

Referring to the drawings, Figs. 1 and 2 depict a process of rolling a dome shaped end cap 10 in a rolling machine 12. The end cap 10 is mounted in a clamp 14 and an edge portion 16 of the end cap 10 is rolled using rolling wheels 18 of the rolling machine 12. As depicted in Figs. 2 and 3, this process forms the edge portion 16 to have a shoulder 20 and a peripheral skirt 22 depending from the shoulder 20.

Turning to Fig. 4, a cylinder 24 is provided having a cylinder wall 26 with an inside diameter that is greater than the outer diameter of the peripheral skirt 22 of the end cap 10. As shown in Fig. 5, the skirt 22 is arranged within the cylinder 24 such that the shoulder 20 of the end cap 10 sits on an end 28 of the cylinder 24 and the skirt 22 extends axially within the cylinder 24. The skirt 22 is then butt welded to the cylinder 24 to form a tank 30 for a hot water heater.

Advantageously, the processes of arranging the skirt 22 in the cylinder 24 and welding the skirt 22 to the cylinder 24 can be performed robotically. This simplifies manufacture and reduces manufacturing costs. Further advantageously, the welded joint is suitable for meeting fatigue testing to Australian Standard 1056 as the arrangement of the end cap and cylinder allows a stronger welded joint, such as a butt welded joint, to be performed. This provides a joint that is capable of withstanding the forces applied during fatigue testing.

Although the invention has been described with reference to a specific example, it will be appreciated by those skilled in the art that the invention may be embodied in other forms.

Claims

Claims:

1. A method of forming a tank, said method comprising the steps of: providing a cylinder having a cylinder wall and a first end; providing a first end cap having a peripheral edge portion; forming the edge portion of the end cap to create a shoulder and a peripheral skirt, the skirt depending from the shoulder and having a smaller outer diameter than the inside diameter of the cylinder wall; arranging the skirt of the end cap within the cylinder such that the shoulder of the end cap sits on the first end of the cylinder and the skirt extends axially within the cylinder; and welding the skirt to the cylinder.

2. The method as claimed in claim 1, wherein the steps of arranging the skirt in the cylinder and welding the skirt to the cylinder are performed robotically.

3. The method as claimed in claim 1 or 2, wherein the step of forming the edge portion of the end cap is performed by rolling.

4. The method as claimed in claim 1, 2 or 3, wherein the step of welding the skirt to the cylinder is performed by butt welding.

5. The method as claimed in any one of the preceding claims, wherein the method further comprises repeating each of the steps in respect of a second end of the cylinder and a respective second end cap.

6. The method as claimed in any one of the preceding claims, thereby forming a hot water heater tank.

7. A tank comprising: a cylinder having a cylinder wall and a first end; and a first end cap having an edge portion, the edge portion having a shoulder and a peripheral skirt, depending from the shoulder, the skirt having a smaller outer diameter than the inside diameter of the cylinder wall, wherein the skirt is arranged within the cylinder such that the shoulder of the end cap sits on the first end of the cylinder and the skirt extends axially within and is welded to the cylinder.

8. The tank as claimed in claim 7, wherein the end cap is substantially dome shaped.

9. The tank as claimed in claim 7 or 8, wherein the tank further comprises a second end and a second end cap, similar to the first end cap, the second end cap being arranged within and welded to the cylinder in the same way as the first end cap.

10. The tank as claimed in claim 7, 8 or 9, wherein the tank is a hot water heater tank.

11. A method of forming a tank substantially as described herein with reference to the accompanying drawings.

12. A tank substantially as described herein with reference to the accompanying drawings.