GB2371253A

GB2371253A - Improvements in pipe shaping

Info

Publication number: GB2371253A
Application number: GB0019532A
Authority: GB
Inventors: Richard Frederick Evans
Original assignee: MECHATRONIC PRODUCTION SYSTEMS
Current assignee: MECHATRONIC PRODUCTION SYSTEMS
Priority date: 2000-08-10
Filing date: 2000-08-10
Publication date: 2002-07-24
Anticipated expiration: 2020-08-10
Also published as: GB2371253B; GB0019532D0

Abstract

A tool 3 for altering the shape or configuration of an open-end portion of a pipe or tube 1 comprises at least one means for applying pressure to deform the pipe or tube 1 and a means for transmitting pressure to the pipe or tube 1. The pressure transmitting means controls the alteration of the shape or configuration of the pipe or tube 1. The pressure transmitting means is provided with an annular recess 4 in its lower face 5 to guide the deformation of the open-end portion of the pipe or tube 1. The pressure applying means can be activated hydraulically, pneumatically or mechanically.

Description

IMPROVEMENTS IN PIPE SHAPING

The present invention relates to a method of altering the shape and configuration of pipes and tubes and to a tool for use in the method. The method and tool are particularly useful in the production of hollow rivets.

Riveting is a process used to secure at least one material to another.

Rivets are formed by the introduction of a tube, usually with a head on one end, through the materials to be secured together followed by the deformation of one or both ends of the tube to hold the materials together.

Hollow rivets are formed by the application of pressure to the open end of a tube of metallic material, which causes the open end to flare out and roll over thereby fixing, for example, layers of material together. The pressure can be applied to the tube by a stationary or rotating tool.

When flaring out the open end of the tube of metallic material, it often tears unless other mechanical methods are used in conjunction with the flaring tool to shape and roll the tube. The use of additional mechanical methods increases the cost and number of processing steps.

When force is applied to a tube of metallic material to form a rivet the tube is in position, for example, holding two pieces of material together and the force applied is often considerable. The application of force to the tube of metallic material can result in distortion of the pieces of material being held together by the rivet and have a detrimental effect on the performance of the final assembly made up of the material held together by the rivets.

The force applied to form a hollow rivet is often a rotational downward force provided by a driven rotating rivet spindle. The rotating rivet spindles are costly and it is not always easy to monitor the quality and consistency of the rivets formed. Furthermore the distance between the centres of the rivets is limited by the working space needed for the riveting spindle.

The aim of the present invention is therefore to create a method and tool for the formation of hollow rivets addressing the problems of tears in the rivets and damage to the materials being riveted together. The method and tool should not impose any limitations on the rivet centre spacing allowing the rivets to be as close as desired.

Accordingly the present invention provides a tool for altering the shape or configuration of an open-end portion of a pipe or tube, the tool comprising at least one means for applying pressure to deform the pipe or tube, means for transmitting pressure to the pipe or tube wherein the pressure transmitting means controls the alteration of the shape or configuration of the pipe or tube.

From another aspect the present invention provides a method of altering the shape or configuration of an open-end of a pipe or tube, the method comprising transmitting pressure from at least one pressure applying means to the pipe or tube wherein the alteration of the shape or configuration of the pipe or tube is controlled by the transmission of pressure.

The pressure transmitting means preferably transmits pressure along the longitudinal axis of the pipe or tube from the open-end portion thereof.

The pressure transmitting means is preferably provided with an annular recess to guide the deformation of the open-end portion during the application. The recess is preferably semi-circular in profile.

The outer circumference of the annular recess is preferably sized to contact the outer surface of the open-end portion of the pipe or tube. The application of pressure causes the outer surface of the open end portion to follow the profile of the annular recess giving rise to the desired alteration of shape or configuration.

The combination of the pressure and pressure transmitting means preferably give rise to inward closure of the open-end of the pipe or tube and outward buckling of the pipe or tube between the open-end portion.

This use of pressure and pressure transmission allows alteration of the shape or configuration of the open-end of the pipe or tube without tearing of the pipe or tube or damage to other material surrounding the pipe or tube during the alteration.

The pressure applying means may be hydraulically activated, pneumatically activated or mechanically activated. Hydraulic and pneumatic pressure may be applied using an appropriate cylinder. Mechanical pressure may be applied using a ballscrew, toggle, flywheel or levers.

The pipe or tube is preferably made from a metallic material, for example steel, brass or aluminium. the pipe or tube is preferably a hollow rivet spindle for alteration of shape or configuration to form a hollow rivet. The tool may be made from tool steel, tungsten carbide, carbon steel or stellite (a trade mark of Deloro Stellite Ltd (Swindon, tek)).

The present invention also provides a hollow rivet formed using the tool and/or the method of the present invention.

The present invention will now be further described with reference to the accompanying figures and examples.

Figure 1 shows the sequence of steps associated with the hollow riveting method of the present invention looking at a cross section through the hollow cylinder and showing the associated tool; and Figure 2 shows the initial deformation step associated with the hollow rivet forming method of the present invention in more detail looking at a cross section of half the hollow cylinder.

Figure 1 shows the sequence of steps undergone to form a rivet by the method of the present invention. The figure shows a cross section through a tube 1 of malleable metallic material such as steel The tube 1 of material is subjected to simultaneous linear compressive force. The tube 1 is held in a locator 2 while the linear force is applied.

The tool 3 of the present invention provides the linear compressive force.

The tool 3 is made from tool steel and is cylindrical in shape having an annular recess 4 in its lower face 5. The recess 4 is of a suitable size to receive an open-end portion la of the tube 1 and is semi-circular in profile.

The tool 3 exerts a load of 1.5kn on the tube 1 which has a diameter of 15mm and a wall thickness of 0.5mm.

To form a hollow rivet according to the process of the present invention a load of 1.5kn is applied through the tool 3 onto the open-end portion la

of the tube 1. The form of the tool is such that the open-end portion la contacts the outer circumference 6 of the recess 4 and inward closure of the open-end portion la occurs followed by outward buckling of the tube below the end portion la (this step is shown in the first two drawings of figure 1 and in more detail in figure 2).

Application of further load through the tool 3 onto the open-end portion la causes further outward buckling of the tube 1 to give enhanced outward form.

EXAMPLE Tests have been carried out to compare the tensile force to failure of rivets formed by the method and tool of the present invention with rivets formed by flaring a tube of metallic material with the application of a load to a 16mm diameter steel ball.

The diameter of the tubes used to prepare the rivets are shown in tables 1 and 2, in each case the wall thickness of the tube was 0.5mm. The tubes were made from Carbon steel EN32 and the force applied was 1.5kn. The force was applied mechanically.

The results of the tests are set out in Tables 1 and 2 below.

Table 1-Rivet of the present invention

RIVET DIAMETER OF RIVET HEAD TENSILE FORCE TO NUMBER (mm) FAILURE (N) 1 10. 84 12066 2 10.80 11538

3 10. 80 13777 4 11. 10 13693

Table 2-Rivet made using 16mm steel ball

RIVET DIAMETER OF RIVET HEAD TENSILE FORCE TO NUMBER (mm) FAILURE (N) 5 11. 30 8293 6 11. 20 8376 7 11. ou7197 8 11. 3 8398

It can be clearly seen from the results of the tests that the rivets of the present invention have improved performance over known rivets.

Claims

1. A tool for altering the shape or configuration of an open-end portion of a pipe or tube, the tool comprising at least one means for applying pressure to deform the pipe or tube, means for transmitting pressure to the pipe or tube wherein the pressure transmitting means controls the alteration of the shape or configuration of the pipe or tube.

2. A tool according to claim 1 wherein the pressure transmitting means transmits pressure along the longitudinal axis of the pipe or tube from the open-end portion thereof.

3. A tool according to claim 1 or claim 2 wherein the pressure transmitting means is provided with an annular recess to guide the deformation of the open-end portion during the application.

4. A tool according to claim 3 wherein the recess is semi-circular in profile.

5. A tool according to claim 3 or claim 4 wherein the outer circumference of the annular recess is sized to contact the outer surface of the open-end portion of the pipe or tube.

6. A tool according to any proceeding claim where the pressure applying means is hydraulically activated, pneumatically activated or mechanically activated.

7. A tool according to any claim 6 wherein the pressure applying means is hydraulically activated and hydraulic pressure is applied using an appropriate cylinder.

8. A tool according to claim 6 wherein the pressure applying means is mechanically applied and mechanical pressure is applied using a ballscrew, toggle, flywheel or levers.

9. A tool according to claim 6 wherein the pressure applying means is pneumatically activated and pneumatic pressure is applied using an appropriate cylinder.

10. A method of altering the shape or configuration of an open-end of a pipe or tube, the method comprising transmitting pressure from at least one pressure applying means to the pipe or tube wherein the alteration of the shape or configuration of the pipe or tube is controlled by the transmission of pressure.

11. A method according to claim 10 wherein the combination of the pressure and pressure transmitting means gives rise to inward closure of the open-end of the pipe or tube and outward buckling of the pipe or tube below the open-end portion.

12. A hollow rivet substantially as described herein and with reference to the drawings.

12. The method according to claim 10 or claim 11 wherein the pipe or tube is a hollow rivet spindle for alteration of shape or configuration to form a hollow rivet.

13. A hollow rivet formed using the tool according to claim 1 or the method according to claim 10.

14. A tool for altering the shape or configuration of an open-ended pipe or tube substantially as described herein and with reference to the drawings. 15. A method of altering the configuration of an open-end of a pipe or tube substantially as described herein and with reference to the drawings.

16. A hollow rivet substantially as described herein and with reference to the drawings. Amendments to the claims have been Hied as follows

1. A tool for altering the shape or configuration of an open-end portion of a pipe or tube, the tool comprising at least one means for applying pressure to deform the pipe or tube and means for transmitting pressure to the pipe or tube wherein the pressure transmitting means controls the alteration of the shape or configuration of the pipe or tube and is provided with an annular recess to guide the deformation of the open-end portion during the application, which recess is semi-circular in profile and has an outer circumference sized to contact the outer surface of the open-end portion of the pipe or tube and wherein the combination of the pressure and pressure transmitting means gives rise to inward closure of the open-end of the pipe or tube and outward buckling of the pipe or tube below the open-end portion.

3. A tool according to Claim 1 or Claim 2 where the pressure applying means is hydraulically activated, pneumatically activated or mechanically activated.

4. A tool according to Claim 3 wherein the pressure applying means is hydraulically activated and hydraulic pressure is applied using an appropriate cylinder.

5. A tool according to Claim 3 wherein the pressure applying means is mechanically applied and mechanical pressure is applied using a ballscrew, toggle, flywheel or levers.

6. A tool according to Claim 3 wherein the pressure applying means is pneumatically activated and pneumatic pressure is applied using an appropriate cylinder.

7. A method of altering the shape or configuration of an open-end of a pipe or tube, the method comprising transmitting pressure through a pressure transmitting means from at least one pressure applying means to the pipe or tube wherein the alteration of the shape or configuration of the pipe or tube is controlled by the transmission of pressure and the combination of the pressure and pressure transmitting means gives rise to inward closure of the open-end of the pipe or tube and outward buckling

of the pipe or tube below the open-end portion, and wherein the pressure r transmitting means is provided with an annular recess to guide the deformation of the open-end portion during the application, which recess is semi-circular in profile and has an outer circumference sized to contact the outer surface of the open-end portion of the pipe or tube.

8. The method according to Claim 7 wherein the pipe or tube is a hollow rivet spindle for alteration of shape or configuration to form a hollow rivet.

9. A hollow rivet formed using the tool according to Claim 1 or the method according to Claim 7.

10. A tool for altering the shape or configuration of an open-ended pipe or tube substantially as described herein and with reference to the drawings.

11. A method of altering the configuration of an open-end of a pipe or tube substantially as described herein and with reference to the drawings.