Method and apparatus for forming piping element connections having multiple outward steps

• US 5,450,738 A
• Filed: 08/31/1993
• Issued: 09/19/1995
• Est. Priority Date: 08/31/1993
• Status: Expired due to Term

• Current Assignee: Mueller International LLC (Mueller Water Products Incorporated)
• Original Assignee: Grinnell Corporation (Johnson Controls International plc)
• Inventors: Chatterley, Charles N., Horgan, Michael W.
• Primary Examiner(s): Larson, Lowell A.
• Application Number:
  US08/114,662
• Time in Patent Office: 749 Days
• Field of Search: 72/105, 72/106, 72/117, 72/118
• US Class Current: 72/106
• CPC Class Codes: B21D 41/02 Enlarging
• CPC Class Codes: F16L 17/04 with longitudinally split or divided sleeve

Abstract

An apparatus for forming a piping element connection with multiple outward steps has first and second rollers, a driver for the second roller, and a positioning roller. The first roller rotates about a first axis, with first and second upper surfaces of rotation centered thereabout, the first surface mean diameter being less than that of the second surface. The first roller has an upper leading edge between the first and second upper surfaces. The second roller is mounted for rotation about a second axis parallel to the first axis, with first and second lower surfaces of rotation centered thereabout, the first surface mean diameter being greater than that of the second surface, and the second roller having a lower trailing edge between the first and second lower surfaces. The first and second rollers are mounted for movement together and apart in a plane of the first and second axes for engagement and forming of multiple outward steps in the piping element connection placed therebetween.

Claims

1. An apparatus for cold roll forming multiple, generally coaxial, outward steps in a circumferential wall of a piping element having a base circumference and a base wall thickness, said apparatus comprising

an outside roller die mounted for rotation about a first axis, and an inside roller die mounted for rotation about a second axis, parallel to said first axis,

said outside roller die defining a first outside roller surface of rotation extending axially and centered about said first axis, and at least a second outside roller surface of rotation extending axially and centered about said first axis said first outside roller surface having a mean diameter and said second outside roller surface having a mean diameter, the mean diameter of said first outside roller surface being less than the mean diameter of said second outside roller surface, and said outside roller die further defining an outside roller leading edge between said first outside roller surface and said second outside roller surface.

said inside roller die defining a first inside roller surface of rotation corresponding and opposed to said first outside roller surface, and extending axially and centered about said second axis, and at least a second inside roller surface of rotation corresponding and opposed to said second outside roller surface and extending axially and centered about said second axis, said first inside roller surface having a mean diameter and said second inside roller surface having a mean diameter, the mean diameter of said first inside roller surface being greater than the mean diameter of said second inside roller surface, and said inside roller die further defining an inside roller trailing edge between said first inside roller surface and said second inside roller surface,

said first outside roller surface and said second roller surface positioned for engagement with an outside surface of the wall of the piping element, and said first inside roller surface and said second inside roller surface positioned for engagement with an inside surface of the wall of the piping element,

said first outside roller surface and said second outside roller surface together with said first inside roller surface and said second inside roller surface defining a nip, said first axis, said second axis and said nip disposed in a common plane,

said outside roller die or said inside roller die defining a stop wall with a stop surface spaced from said outside roller leading edge or said inside roller trailing edge, respectively, and said second outside or inside roller surface being relatively more spaced from said stop surface than said first outside or inside roller surface, respectively, said stop surface positioned for engagement by an end surface of the piping element, and

said first inside roller surface further defining a tapering surface having a first diameter in a region of said inside roller trailing edge and a second diameter in a region of said stop surface, said first diameter being greater than said second diameter, and

means for driving at least said outside roller die or said inside roller die to rotate about its respective axis, and

means for urging together said outside roller die and said inside roller die, each being mounted for relative movement together and apart, in said plane of said first axis, said second axis and said nip, in a manner to engage the wall of a piping element disposed in said nip therebetween and applying sufficient compressive force for forming by cold rolling of multiple outward steps by reducing the thickness of the wall of the piping element connection disposed therebetween in said nip,

said first outside roller surface being disposed in substantial axial registration with said first inside roller surface, and said second outside roller surface being disposed in substantial axial registration with said second inside roller surface, and

said outside roller leading edge being offset axially from said inside roller trailing edge to provide a predetermined spacing dependent upon the base wall thickness of the piping element in which multiple outward steps are to be formed,

whereby, during rotation of said outside roller die and said inside roller die, the wall thickness of the piping element is reduced about at least a first circumferential region of limited axial extent and a second region of limited axial extent, to increase the circumference of the piping element in the first and second circumferential regions by conservation of wall material, the degree of reduction of wall thickness, and the resulting circumference, in the first region between corresponding, opposed said first outside and inside roller surfaces being greater than the degree of reduction of wall thickness, and resulting circumference, in the second region between corresponding opposed said second outside and inside roller surfaces relatively more spaced from said stop surface, thereby to form by cold rolling multiple outward steps in a piping element connection placed in said nip between said outside and inside roller dies, the resulting circumference in the first region and the resulting circumference in the second region being greater than the base circumference and the resulting wall thickness in the first region and the resulting wall thickness in the second region being less than the base wall thickness.

2. The apparatus of claim 1 wherein said taper has an angle of approximately 1°

to 3°

relative to said second axis.

3. The apparatus of claim 1 wherein said stop wall comprises an end inside roller surface of said inside roller die adjacent said first inside roller surface and spaced from said inside roller trailing edge, said end inside roller surface extending radially outwardly and generally perpendicular to said second axis.

4. The apparatus of claim 1 wherein said apparatus comprises:

a first positioning roller mounted for rotation about a third axis parallel to said first axis and offset to a first side of said plane of said first axis, said second axis and said nip, and

a second positioning roller mounted for rotation about a fourth axis parallel to said first axis and offset to a second side, opposite said first side, from said plane of said first axis, said second axis and said nip and having a surface positioned for engagement with an outside surface of the piping element.

5. The apparatus of claim 4 wherein said third axis is spaced from said plane by a first positioning distance and said fourth axis is spaced from said plane by a second positioning distance different from said first positioning distance.

6. The apparatus of claim 1, wherein said apparatus further comprises at least one positioning roller mounted for rotation about a third axis parallel to said first axis and offset from said plane of said first and second axes and having a surface positioned for engagement with a surface of the piping element to hold the piping element with its axis at a predetermined offset angle.

7. The apparatus of claim 6 wherein said offset angle is approximately 0.5°

to 2°

.

8. The apparatus of claim 6, wherein said at least one positioning roller is positioned for engagement with an outside surface of the piping element.

9. The apparatus of claim 8 wherein said offset angle is approximately 0.5°

to 2°

.

10. The apparatus of claim 1, wherein the multiple outward steps formed by said apparatus are generally parallel to a centerline of a piping element in which said steps are formed by cold rolling.

11. A method for cold rolling a piping element having a base circumference and a base wall thickness to form multiple, generally coaxial, outward steps in a circumferential wall of the piping element, said method comprising the steps of:

a. providing a cold rolling apparatus comprising an outside roller die mounted for rotation about a first axis, and an inside roller die mounted for rotation about a second axis, parallel to said first axis, said outside roller die defining a first outside roller surface of rotation extending axially and centered about said first axis, and at least a second outside roller surface of rotation extending axially and centered about said first axis, said first outside roller surface having a mean diameter and said second outside roller surface having a mean diameter, the mean diameter of said first outside roller surface being less than the mean diameter of said second outside roller surface, and said outside roller die further defining an outside roller leading edge between said first outside roller surface and said second outside roller surface, said inside roller die defining a first inside roller surface of rotation corresponding and opposed to said first outside roller surface, and extending axially and centered about said second axis, and at least a second inside roller surface of rotation corresponding and opposed to said second outside roller surface and extending axially and centered about said second axis, said first inside roller surface having a mean diameter and said second inside roller surface having a mean diameter, the mean diameter of said first inside roller surface being greater than the mean diameter of said second inside roller surface, and said inside roller die further defining an inside roller trailing edge between said first inside roller surface and said second inside roller surface, the first outside roller surface and said second outside roller surface positioned for engagement with an outside surface of the wall of the piping element, and said first inside roller surface and said second inside roller surface positioned for engagement with an inside surface of the wall of the piping element, said first outside roller surface and said second outside roller surface together with said first inside roller surface and said second inside roller surface defining a nip, said first axis, said second axis and said nip disposed in a common plane, said outside roller die or said inside roller die defining a stop wall with a stop surface spaced from said outside roller leading edge or said inside roller trailing edge, respectively, and said second outside or inside roller surface being relatively more spaced from said stop surface than said first outside or inside roller surface, respectively, said stop surface positioned for engagement by an end surface of the piping element, and said first inside roller surface further defining tapering surface having a first diameter in a region of said inside roller trailing edge and a second diameter in a region of said stop surface, said first diameter being greater than said second diameter, and means for driving at least said outside roller die or said inside roller die to rotate about its respective axis, and means for urging together said outside roller die and said inside roller die, each being mounted for relative movement together and apart, in said plane of said first axis, said second axis and said nip, in a manner to engage the wall of a piping element disposed in said nip therebetween and applying sufficient compressive force for forming by cold rolling of multiple outward steps by reducing the base thickness of the wall of the piping element connection disposed therebetween in said nip, said first outside roller surface being disposed in substantial axial registration with said first inside roller surface, and said second outside roller surface being disposed in substantial axial registration with said second inside roller surface, and said outside roller leading edge being offset axially from said inside roller trailing edge to provide a predetermined spacing dependent upon the base wall thickness of the piping element in which multiple outward steps are to be formed;

b. positioning an end of a piping element connection to be formed with multiple, outward steps by cold rolling in the nip, with an end surface of the piping element engaged with said stop surface, with the piping element angularly offset away from the first and second axes;

c. while supporting the piping element at a point spaced from the end engaged in the nip, engaging the first and second outside roller surfaces of the outside roller die upon the outside wall surface of the piping element and engaging the first and second inside roller surfaces of the inside roller die upon the inside wall surface of the piping element;

d. driving the inside roller die while engaging the outside roller leading edge upon the outside wall surface of the piping element in manner to apply a torque to urge the piping element toward the stop surface; and

e. during rotation of the outside and inside roller dies, applying force to urge the outside roller surface of the outside roller die and the inside roller surface of the inside roller die together, reducing the base wall thickness of the wall of the piping element about at least a first circumferential region of limited axial extent, corresponding generally to the opposed first outside and inside roller surfaces, and a second region of limited axial extent, corresponding generally to the opposed second outside and inside roller surfaces relatively more spaced from the stop surface, to increase the circumference of the piping element in the first and second circumferential regions by conservation of wall material, with the degree of reduction of wall thickness, and the resulting circumference, in the first region being greater than the degree of reduction of wall thickness, and resulting circumference, in the second region, thereby to form by cold rolling multiple outward steps in a piping element connection placed in the nip between the outside and inside roller dies, the resulting circumference in the first region and the resulting circumference in the second region being greater than the base circumference and the resulting wall thickness in the first region and the resulting wall thickness in the second region being less than the base wall thickness.