Roller for roll forming

Abstract

A roller for engaging an outer surface of a pipe element during roll forming has a perimeter region defined by three faces. A channel is positioned in one of the faces. The channel extends circumferentially around the perimeter region and provides a void space that reduces the contact area between the face and the side surface of a circumferential groove formed in the pipe element during roll forming. The reduced contact area reduces frictional heating of the pipe and roller as well as the tendency of the roller to slip relative to the floor surface of the groove due to axial force engendered when an asymmetrical groove is formed.

Claims

1. An apparatus for roll forming a pipe element, said apparatus comprising: an outer roller engageable with an outer surface of said pipe element, said outer roller comprising: a body rotatable about a first axis of rotation, said body having a perimeter region positioned radially distal to and surrounding said first axis, said perimeter region comprising: a first face oriented transversely to said first axis; a second face, contiguous with said first face; a third face, contiguous with said second face and oriented transversely to said first axis; a channel positioned in said third face and extending around said perimeter region; said apparatus further comprising: an inner roller engageable with an inner surface of said pipe element, said inner roller being rotatable about a second axis of rotation oriented substantially parallel to said first axis; an actuator for moving said inner and outer rollers toward and away from one another; and a motor for rotating one of said inner and outer rollers.

2. The apparatus according to claim 1, wherein said body has a cylindrical cross section.

3. The apparatus according to claim 2, wherein said first axis is coaxial with said cylindrical cross section.

4. The apparatus according to claim 1, wherein said first face is angularly oriented with respect to said first axis.

5. The apparatus according to claim 4, wherein said third face is oriented substantially perpendicularly to said first axis.

6. The apparatus according to claim 5, wherein said second face is oriented substantially parallel to said first axis.

7. The apparatus according to claim 4, wherein said first face has an orientation angle from 30 to 70 with respect to said first axis.

8. The apparatus according to claim 4, wherein said first face has an orientation angle of 50 with respect to said first axis.

9. The apparatus according to claim 1, wherein said third face is oriented substantially perpendicularly to said first axis.

10. The apparatus according to claim 1, wherein said second face is oriented substantially parallel to said first axis.

11. The apparatus according to claim 1, wherein said inner roller comprises a circumferential trough receiving said perimeter region when said inner and outer rollers are moved toward one another, said trough defined by a first shoulder and a second shoulder positioned in spaced relation from said first shoulder, said first shoulder being positioned adjacent to but not underlying said first face of said perimeter region.

12. An apparatus for roll forming a pipe element, said apparatus comprising: an outer roller engageable with an outer surface of said pipe element and rotatable about a first axis of rotation, said outer roller comprising: a body having an outer surface surrounding said first axis, said outer surface comprising a raised surface portion extending around said body and projecting outwardly from said first axis, said raised surface portion comprising: a first face oriented transversely to said first axis; a second face, contiguous with said first face; a third face, contiguous with said second face and oriented transversely to said first axis; a channel positioned in said third face and extending around said body; said apparatus further comprising: an inner roller engageable with an inner surface of said pipe element, said inner roller being rotatable about a second axis of rotation oriented substantially parallel to said first axis; an actuator for moving said inner and outer rollers toward and away from one another; and a motor for rotating one of said inner and outer rollers.

13. The apparatus according to claim 12, wherein said body has a cylindrical cross section.

14. The apparatus according to claim 13, wherein said first axis is coaxial with said cylindrical cross section.

15. The apparatus according to claim 12, wherein said first face is angularly oriented with respect to said first axis.

16. The apparatus according to claim 15, wherein said third face is oriented substantially perpendicularly to said first axis.

17. The apparatus according to claim 16, wherein said second face is oriented substantially parallel to said first axis.

18. The apparatus according to claim 15, wherein said first face has an orientation angle from 30 to 70 with respect to said first axis.

19. The apparatus according to claim 15, wherein said first face has an orientation angle of 50 with respect to said first axis.

20. The apparatus according to claim 12, wherein said third face is oriented substantially perpendicularly to said first axis.

21. The apparatus according to claim 12, wherein said second face is oriented substantially parallel to said first axis.

22. The apparatus according to claim 12, wherein said inner roller comprises a circumferential trough receiving said raised surface portion when said inner and outer rollers are moved toward one another, said trough defined by a first shoulder and a second shoulder positioned in spaced relation from said first shoulder, said first shoulder being positioned adjacent to but not underlying said first face of said raised surface portion.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a partial longitudinal sectional view of a roller set according to the prior art for roll forming circumferential grooves in pipe elements;

(2) FIG. 1A is a longitudinal sectional view taken at circle 1A of FIG. 1 and shown on an enlarged scale;

(3) FIG. 2 is an isometric view of an apparatus for roll forming pipe elements;

(4) FIGS. 3-5 are partial longitudinal sectional views of a portion of the apparatus shown in FIG. 2 illustrating use of an example outer roller according to the invention; and

(5) FIG. 3A is a longitudinal sectional view taken at circle 3A of FIG. 3 and shown on an enlarged scale.

DETAILED DESCRIPTION

(6) FIG. 2 shows an apparatus 38 for roll forming pipe elements. Apparatus 38 comprises a housing 40 on which an inner roller 42 and an outer roller 44 according to the invention are rotatably mounted. Inner roller 42 rotates about rotation axis 46, in this example driven by electrical motor 48. Outer roller 44 is an idler and is mounted on a yoke 50 for rotation about an axis 52, preferably oriented substantially parallel (in both the horizontal and vertical planes) to axis 46 of the inner roller 42. Yoke 50 is movable toward and away from inner roller 42 as illustrated by arrow 54, in this example by a hydraulic actuator 56.

(7) As shown in FIGS. 3 and 3A, an example outer roller 44 according to the invention comprises a body 58 with axis of rotation 52. Body 58 has a perimeter region 60 positioned radially distal to axis 52. Perimeter region 60 surrounds axis 52 and comprises a first face 62 oriented transversely to axis 52, a second face 64 contiguous with the first face 62, and a third face 66, contiguous with the second face 64 and oriented transversely to axis 52. As shown in detail in FIG. 3A, a channel 68 is positioned in the third face 66. Channel 68 extends around the perimeter region 60. Outer roller 44 may also comprise an outer surface 70 that surrounds axis of rotation 52. In this example embodiment the perimeter region 60 may be described as a raised surface portion extending around the body 58 and projecting outwardly from the outer surface 70 and axis 52.

(8) In the particular example embodiment of outer roller 44 shown in FIGS. 3 and 3A the body 58 has a cylindrical cross section, with the axis of rotation 52 being coaxial therewith. Outer roller 44 is designed to form an asymmetrical circumferential groove in a pipe element, with first face 62 angularly oriented with respect to axis 52, second face 64 being substantially parallel to axis 52, and the third face 66 being oriented substantially perpendicular to axis 52. In a practical example of an outer roller 44, the first face 62 may have an orientation angle 72 relative to axis 52 from about 30 to about 70, with an orientation angle 72 of about 50 being thought advantageous.

(9) In operation, as shown in FIGS. 4 and 5, the inner surface 12 of pipe element 14 is engaged with the inner roller 42, the end of the pipe element preferably engaging the inner roller's flange 74. Hydraulic actuator 56 (see also FIG. 2) moves the outer roller 44 into engagement with the outer surface 18 of pipe element 14. Motor 48 rotates the inner roller 42 about axis 46 while the actuator 56 forces the outer roller 44 against the outer surface 18 of the pipe element 14, thereby roll forming a circumferential groove 76 in the pipe element, the outer roller 44 rotating about its axis 52 as an idler and the pipe element 14 rotating about its longitudinal axis 22.

(10) Due to the asymmetrical shape of the perimeter region 60 that forms the circumferential groove 76 in the pipe element 14, there will be an axially oriented component load between the third face 66 of outer roller 44 and the side surface 78 of groove 76 as illustrated by arrow 80 in FIGS. 3A and 5. In prior art outer rollers 16 lacking a channel 68 in the face 34 opposite to the angled face 28 (see FIG. 1A) the axial load 32 increases the friction between the face 34 and the side surface 36 of the circumferential groove 24 in the pipe element. However, when channel 68 is present, as in the example outer roller embodiment 44 according to the invention as shown in FIGS. 3A, 4 and 5, the channel 68 provides a void space that reduces the contact area between third face 66 and groove side surface 78. It is thought that third face 66 cannot gain purchase against the side surface 78 due to the reduced contact area afforded by the void space provided by channel 68, and, consistent with observation, there is significantly less slippage between second surface 64 of roller 44 and the floor surface 82 of groove 76.

(11) As illustrated in FIG. 3A, it is found that the axially oriented component load 80 itself can be reduced by controlling the width 84 of the trough 86 in the inner roller 42 which receives the deformed portion of the pipe element 14 comprising the groove 76. The trough 86 is defined by first and second shoulders 88 and 90 positioned in spaced relation. To reduce the axially oriented component load 80, width 84 is controlled by the position of shoulder 88 relative to the first face 62 of perimeter region 60. As shown in FIG. 3A, the reduction of the axially oriented component load 80 is advantageously effected by positioning the shoulder 88 of the trough 86 adjacent to but not underlying the first face 62 of the perimeter region 60. This relation between trough shoulder 88 and first face 62 is believed to reduce the pinching of the pipe element 14 between the rollers 42 and 44, thereby reducing the axially oriented component load 80. This force reduction reduces slipping between the second face 64 and groove floor 82, consequently friction between the rollers and the pipe element is reduced and the groove is formed with less vibration, less applied force and less heating.