Method and apparatus for manufacturing a pipe element having shoulder, groove and bead

Field of the Invention

This invention relates to an apparatus for making pipe elements joined together by mechanical couplings and methods for making such pipe elements with that apparatus.

Background

Various challenges are encountered when designing pipe elements to be joined by mechanical pipe couplings. Such couplings comprise two or more coupling segments joined in end to end relation by threaded fasteners. The segments surround a central space which receives the pipe elements. Each segment has a pair of arcuate projections known as "keys" which engage the outer surfaces of the pipe elements. The keys are often received in circumferential grooves in the pipe elements which provide a positive mechanical engagement against bending and axial loads applied to the joint. Each segment also defines a channel between its pair of arcuate projections which receives a ring-shaped gasket. The gasket is typically compressed between the segments and the pipe elements to effect a fluid tight joint.

Circumferential grooves are advantageously formed by cold working the sidewall of the pipe element because, unlike cut grooves, material is not removed from the pipe sidewall and thus thinner walled pipe elements may be grooved by the cold working process. It is advantageous to use thinner walled pipe elements for weight and cost savings in high pressure and /or high load applications. However, prior art cold working methods and pipe designs do not produce coupling and pipe element engagement features adequate for high loads and pressures sustainable by comparable cut groove systems used on thicker walled pipe elements. There are clear advantages to be had through improvements to the design and manufacture of thin walled grooved pipe elements by cold working which will allow thin walled grooved pipe elements to be joined by mechanical couplings and used in high pressure/high load applications.

<patcit id="pcit0001" dnum="US6196039B1"><text>US 6 196 039 B1</text></patcit> discloses groove rollers, an outside roller with a peripheral surface that includes a first protrusion configured to form the groove, and a second protrusion, an inside roller has a peripheral surface that includes a notch configured to receive the first protrusion, and has a second notch configured to receive the second protrusion.

Summary

The present invention is directed to device for forming the ends of a pipe element according to claim 1. The device comprising a first roller and second roller (80) for imparting a shape to a sidewall of a pipe element, wherein said first roller rotates about an axis. The first roller comprises a first segment having a first outer diameter and a second segment positioned contiguous with the first segment. The second segment has a second outer diameter smaller than the first outer diameter. A third segment is positioned contiguous with the second segment and has a third outer diameter larger than the second outer diameter. An eighth segment is positioned contiguous with the third segment and has an eighth outer diameter smaller than the second outer diameter. A ninth segment is positioned contiguous with the eighth segment and has an eighth outer diameter approximately equal to the second outer diameter.

The second roller comprises a fourth segment having a fourth outer diameter and a fifth segment positioned contiguous with said fourth segment and having a fifth outer diameter greater than the fourth outer diameter. A sixth segment is positioned contiguous with said fifth segment and has an sixth outer diameter less than the fifth outer diameter. A seventh segment is positioned contiguous with said sixth segment and has a seventh outer diameter approximately equal to the fifth outer diameter.

The fifth segment comprises a first annular surface positioned adjacent to the fourth segment and oriented substantially perpendicularly to the second axis, and a second annular surface positioned adjacent to the sixth segment and oriented angularly with respect to the second axis.

The device comprises a support frame. The first roller is mounted on the support frame and is rotatable about a first axis. The first roller is adapted to engage an inner surface of the pipe element. Means for rotating the first roller about the first axis are also provided. The second roller is mounted on the support frame and is rotatable about a second axis oriented substantially parallel to the first axis. The second roller is movable toward and away from the first roller and is adapted to engage an outer surface of the pipe element. Means for moving the second roller relatively to the first roller for compressing the sidewall while the rollers rotate are also provided. The rollers are arranged relatively to one another on the support frame such that: the fourth segment is aligned with the first segment; the fifth segment is aligned with the second segment; the sixth segment is aligned with the third segment.

The rotating means may comprise an electric motor or a hydraulic motor operated by a pump, and the moving means may comprise a hydraulic actuator or a jackscrew by way of example.

The invention further encompasses a method of imparting a shape to the sidewall of a pipe element having an inner surface and an outer surface according to claim 8 by using the device according to the invention. The method comprises: contacting the inner surface of the pipe element at a first point on the first segment of the first roller; contacting the outer surface of the pipe element at a third point on the fifth segment of the second roller; rotating one of the first and second rollers thereby causing the other of the first and second rollers and the pipe element to rotate, the first roller circumferentially traverses the inner surface of the pipe element, and the second roller circumferentially traverses the outer surface of the pipe element; moving one of the first and second rollers toward the other of the first and second rollers and deforming the sidewall of the pipe element through contact between the inner surface of the pipe element and the first and third segments of the first roller, and contact between the outer surface of the pipe element and the fifth and seventh segments of the second roller; continue moving one of the first and second rollers toward the other of the first and second rollers and compressing the sidewall of the pipe element between the first segment of the first roller and the fourth segment of the second roller; continue moving one of the first and second rollers toward the other of the first and second rollers and compressing the sidewall of the pipe element between the second segment of the first roller and the fifth segment of the second roller; and continue moving one of the first and second rollers toward the other of the first and second rollers and compressing the sidewall of the pipe element between the third segment of the first roller and the fifth and seventh segments of the second roller.

Brief Description of the Drawings

<ul id="ul0001" list-style="none" compact="compact"><li><figref idref="f0001">Figures 1</figref> and <figref idref="f0002">1A</figref> are longitudinal sectional views of example pipe elements not according to the invention;</li><li><figref idref="f0003">Figure 2</figref> is an isometric view of a valve including an example pipe element elements not according to the invention;</li><li><figref idref="f0004">Figure 3</figref> is an exploded isometric view of a combination of pipe elements and a pipe coupling elements not according to the invention;</li><li><figref idref="f0005">Figures 3A and 3B</figref> are elevational views of pipe coupling embodiments elements not according to the invention;</li><li><figref idref="f0006 f0007">Figures 4-6</figref> are longitudinal sectional views of a combination of pipe elements and a pipe coupling elements not according to the invention;</li><li><figref idref="f0008">Figure 7</figref> is an isometric view of an example roll forming machine according to the invention for manufacturing pipe elements using a roll forming method;</li><li><figref idref="f0009">Figure 8</figref> is an elevational view of an example combination of rollers used to roll form pipe elements according to the invention;</li><li><figref idref="f0010 f0011 f0012">Figures 9-11</figref> are longitudinal sectional views illustrating an example method of roll forming pipe elements according to the invention;</li></ul>

[Detailed Description

The invention concerns methods and devices for cold working pipe elements to receive couplings and form a fluid tight joint. Throughout this document the term "pipe element" means any tubular structure, including, for example, pipe stock 10 as shown in <figref idref="f0001">Figure 1</figref>, as well as the tubular portion 12 of a fluid handling or control component such as the valve 14 shown in <figref idref="f0003">Figure 2</figref>. Other components, such as pumps and strainers, as well as fittings such as tees, elbows, bends and reducers are also included as having or comprising "pipe elements" as defined herein.

As shown in <figref idref="f0001">Figure 1</figref>, pipe element 10 has an outer diameter 16 which passes through a point on a longitudinal axis 18 at the pipe element's center of curvature. At least one end 20 of pipe element 10 is configured to receive a key of a mechanical coupling (not shown), the configuration comprising a shoulder 22 positioned at the end 20, a groove 24 positioned adjacent to the shoulder 22, and a bead 26 positioned contiguous with the groove 24.

As illustrated in detail in <figref idref="f0001">Figure 1</figref>, shoulder 22 extends circumferentially around the pipe element and has an outwardly facing surface 28. Surface 28 has an outer diameter 30 that is greater than the outer diameter 16 of the pipe element 10 excluding the shoulder. Shoulder 30 also has an outwardly facing curved surface 32. Curved surface 32 also extends circumferentially around the pipe element and has a center of curvature on an axis 34 oriented perpendicular to the longitudinal axis 18 of the pipe element 10. In <figref idref="f0001">Figure 1</figref>, axis 34 is shown perpendicular to the viewing plane and is therefore seen end on.

Groove 24 is defined by a first side surface 36 which is positioned contiguous with the curved surface 32 of the shoulder 30. Side surface 36 may be oriented angularly. The orientation angle 41 may range from about 80° to about 85° with respect to the longitudinal axis 18. In another embodiment, the side surface 36 maybe oriented substantially perpendicularly to longitudinal axis 18. "Substantially perpendicularly" as used herein refers to an angular orientation which may not be exactly perpendicular, but is established as close as practicable in view of manufacturing practices and tolerances. Perpendicular orientation of the first side surface 36 stiffens the pipe element radially and helps it maintain its roundness.

A second side surface 38 further defines the groove 24. Second side surface 38 is positioned in spaced apart relation to the first side surface 36 and is oriented angularly with respect to the longitudinal axis 18. Side surface 38 may have an orientation angle 40 from about 40° to about 70° or about 45° to about 65°. In the particular embodiment shown in <figref idref="f0001">Figure 1</figref>, orientation angle 40 is about 55° which is considered advantageous when the groove receives keys of a mechanical coupling as shown in <figref idref="f0004 f0005 f0006 f0007">Figures 3-6</figref>.

A floor surface 42 extends between the first side surface 36 and the second side surface 38 of groove 24. In the example embodiment shown, the floor surface 42 is substantially parallel to the longitudinal axis 18 and has an outer diameter 44 which is less than the outer diameter 16 of the pipe element excluding the groove. The groove 24 also has an inner diameter 17 which, in the embodiment shown in <figref idref="f0001">Figure 1</figref>, is approximately equal to the inner diameter 19 of the pipe element 10.

Bead 26 is positioned contiguous with the second side surface 38 of the groove 24 and also extends circumferentially around the pipe element. The bead 26 projects outwardly away from axis 18 and has an apex 46 with an outer diameter 48 greater than the outer diameter 16 of the pipe element excluding the bead. In the example embodiment shown in <figref idref="f0001">Figure 1</figref>, the diameter 48 of the apex 46 is less than the outer diameter 30 of shoulder 22. Bead 26 increases the radial stiffness of the pipe element and thereby helps maintain its roundness.

As shown in <figref idref="f0002">Figure 1A</figref>, a beadless pipe element embodiment 10a is also feasible. Similar to the embodiment 10 shown in <figref idref="f0001">Figure 1</figref>, for the embodiment 10a in <figref idref="f0002">Figure 1A</figref> the floor surface 42 is substantially parallel to the longitudinal axis 18 and has an outer diameter 44 which is less than the outer diameter 16 of the pipe element excluding the groove. The groove 24 also has an inner diameter 17 which is approximately equal to the inner diameter 19 of the pipe element 10a.

For pipe stock, the configuration of the end of the pipe element 10 (shoulder 22, groove 24 and bead 26) is the same at both ends (not shown for clarity), but other configurations are also feasible wherein the ends may be dissimilar. Furthermore, the pipe elements 50 at opposite ends of valve 14 also have the above-described end configurations which allow the valve, or any other fluid control component or fitting, to be joined to other pipe elements using mechanical couplings, examples of which are shown in <figref idref="f0004">Figures 3</figref>, <figref idref="f0005">3A and 3B</figref>. Alternately, valves and other fluid control components and fittings may also have dissimilar end configurations.

In one embodiment, illustrated in <figref idref="f0004">Figure 3</figref>, mechanical coupling 52 comprises two or more segments 54 attached to one another in end to end relation, in this example by threaded fasteners 56. The segments 54 surround a central space 58 which receives the pipe elements 10 to join them in a fluid tight joint. An elastomeric gasket 60 is captured between the segments 54 and has inwardly facing sealing surfaces 62 which engage the outwardly facing surfaces 28 of shoulders 24 to ensure fluid tightness. Each segment has a pair of arcuate surfaces or keys 64 which project inwardly toward the central space and are received within the grooves 24 of the pipe elements 10.

In another embodiment, shown in <figref idref="f0005">Figure 3A</figref>, the coupling 53 comprises a single segment formed of a unitary body 55 having ends 57 and 59 in spaced apart, facing relation. Bolt pads 61 extend from the ends 57 and 59 and a fastener 63 extends between the bolt pads for drawing them together upon tightening of the fastener. The unitary body surrounds a central space 65 which receives the pipe elements to form a joint. Keys 67 in spaced relation on either side of the coupling 53 extend circumferentially along the unitary body 55 and project radially inwardly. A gasket 60 similar to that as described above is positioned between the keys. Tightening of the fastener 63 draws the keys 67 into engagement with grooves in the pipe elements and compresses the gasket 60 between the unitary body 55 and the pipe elements.

<figref idref="f0005">Figure 3B</figref> shows another coupling embodiment 69, formed of two segments 71 and 73 joined at one end by a hinge 75. The opposite ends 77 and 79 of the segments are in spaced apart facing relation and connected by a fastener 81. Segments 71 and 73 also have circumferential keys 83 in spaced relation and a gasket 60 is positioned between them. The segments surround a central space 65 which receives the pipe elements to form a joint. Tightening of the fastener 81 draws the keys 83 into engagement with grooves in the pipe elements and compresses the gasket 60 between the segments and the pipe elements.

A joint may be formed between two pipe elements 10 by first disassembling the coupling 52 (see <figref idref="f0004">Figure 3</figref>) and slipping the gasket 60 over an end of one of the pipe elements. The end of the other pipe element is then aligned in proximity with the end of the first pipe element, and the gasket is positioned so as to bridge the small gap between the two pipe element ends, with the sealing surfaces 62 of the gasket engaging respective outer surfaces 28 of the shoulders 24 of each pipe element. Next the coupling segments 54 are positioned surrounding the gasket 60 and the ends of the pipe elements with the keys 64 aligned with respective grooves 24 in each pipe element. Fasteners 56 are then applied and tightened so as to draw the segments toward one another, engage the keys 64 within respective grooves 24 and compress the gasket 60 against the pipe elements so as to form a fluid tight joint.

In an alternate embodiment, <figref idref="f0006 f0007">Figures 4-6</figref> show in detail the engagement of the pipe elements 10 with an installation ready type coupling 52 wherein the segments 54 are pre-assembled and held in spaced relation from one another by fasteners 56, the segments being supported on the gasket 60. The segments are sufficiently far apart that the pipe elements 10 may be inserted into the central space 58 without disassembling the coupling as shown in <figref idref="f0006">Figures 4 and 5</figref>. Note that the outwardly facing surfaces 28 of shoulders 22 engage the sealing surfaces 62 of the gasket 60 and the keys 64 align with the grooves 24 in each of the pipe elements. As shown in <figref idref="f0007">Figure 6</figref>, the fasteners 56 (see also <figref idref="f0001">Figure 1</figref>) joining the segments 54 to one another are tightened, drawing the segments toward one another. This compresses the gasket 60 against the pipe elements to effect a seal and forces the keys 64 into the grooves 24 to effect a positive mechanical connection between the coupling and the pipe elements 10 to effect the joint. In one embodiment, shown in detail in <figref idref="f0007">Figure 6</figref>, the keys 64 have a cross sectional shape that is compatible with the grooves, and the keys are dimensioned such that a first lateral key surface 66 engages the groove first side surface 36, and a second lateral key surface 68 engages the angularly oriented second side surface 38 of the groove. It is advantageous that the surfaces 68 and 38 have complementary orientation angles to maximize surface to surface contact. Orientation angles for lateral key surface 68 measured with respect to the pipe element longitudinal axis 18 (see also <figref idref="f0001">Figure 1</figref>) from about 40° to about 70°, or from about 45° to about 65°, or about 55° are contemplated. It is also advantageous that surfaces 66 and 36 have complementary orientation angles. Orientation angles for lateral key surface 66 measured with respect to the pipe element longitudinal axis 18 (see also <figref idref="f0001">Figure 1</figref>) from about 80° to about 85° are contemplated.

In general for this embodiment there will be a gap 70 between the groove floor surface 42 and a radially facing surface 72 of the key 64. This is due to tolerance variations in both the pipe element and the coupling. Some gap between surfaces 42 and 72 is advantageous to ensure that the keys engage the groove with a wedging action that provides rigidity to the joint and maintains the pipe elements in spaced relation to one another under axial compression and tension loads. Formation of the joint using coupling embodiments 53 and 69 shown in <figref idref="f0005">Figures 3A and 3B</figref> proceeds similarly as described above for the installation ready embodiment. Other embodiments are also feasible, for example, wherein only the vertical key surface 66 is in contact with the groove first side surface 36, or only the angularly oriented key surface 68 is in contact with the second side surface 38 of the groove 24. It is also possible that the coupling segments float on the gasket 60, wherein none of the key surfaces are in contact with the groove surfaces, at least initially until the joint is subjected to load.

Roll Forming

<figref idref="f0008">Figure 7</figref> shows a device 74 for roll forming the ends of a pipe element and imparting a shape to its sidewalk Device 74 comprises a support frame 76 on which is mounted a first or inner roller 78, and a second or outer roller 80. Inner roller 78 is mounted for rotation about an axis 82 and is adapted to engage and support an inner surface of a pipe element during the cold working process disclosed herein. Means 84 for rotating the inner roller are provided with device 74. Such means may include, for example an electric motor, or a hydraulic motor operated by a pump. Outer roller 80 is mounted on a yoke 86 and is free to rotate about an axis 88 which is substantially parallel to the axis of rotation 82 of the inner roller 78. Yoke 86 allows the outer roller 80 to move toward and away from the inner roller 78 so that it may engage an outer surface of the pipe element during roll forming. Means 90 are provided to move the outer roller 80 on yoke 86, and such means may comprise, for example, a hydraulic actuator or a jackscrew.

An example roller combination 92 of inner and outer rollers 78 and 80 according to the invention is shown in detail in <figref idref="f0009">Figure 8</figref>. Inner roller 78 is formed of a plurality of segments having different outer diameters which cooperate with various segments comprising the outer roller 80 (which are also distinguishable from one another by their respective outer diameters) to impart a desired shape to the pipe element sidewall as described herein. Inner roller 78 is comprised of a first segment 94 having an outer diameter 94a, a second segment 96 positioned contiguous with the first segment and having an outer diameter 96a smaller than outer diameter 94a, a third segment 98 positioned contiguous with the second segment and having an outer diameter 98a larger than outer diameter 96a, a eighth segment 100 positioned contiguous with the third segment and having an outer diameter 100a smaller than outer diameter 96a, and a ninth segment 102 positioned contiguous with the eighth segment (100) and having an outer diameter 102a approximately equal to outer diameter 96a. Similarly, outer roller 80 is comprised of a fourth segment 104 having an outer diameter 104a, a fifth segment 106 positioned contiguous with the fourth segment 104 and having an outer diameter 106a greater than outer diameter 104a, a sixth segment 108 positioned contiguous with the fifth segment 106 and having outer diameter 108a less than outer diameter 106a, and a seventh segment 110 positioned contiguous with the sixth segment 108 and having an outer diameter 110a approximately equal to outer diameter 106a.

When the roller combination shown in <figref idref="f0009">Figure 8</figref> is mounted on device 74 for cold working the sidewall of a pipe element, the rollers are aligned so as to cooperate with one another and impart the desired sidewall shape. In the example shown in <figref idref="f0009 f0010 f0011 f0012">Figures 8-11</figref>, the segment 94 on the inner roller 78 is aligned with segment 104 on the outer roller 80; segment 96 on the inner roller is aligned with segment 106 on the outer roller; segment 98 on the inner roller is aligned with segment 108 on the outer roller, and segments 100 and 102 on the inner roller are aligned with segment 110 on the outer roller.

Annular surfaces on each of the rollers, formed when there are contiguous segments on the same roller having different outer diameters, also cooperate in pairs with one another to impart the desired shape to the pipe element sidewall. As further shown in <figref idref="f0009">Figure 8</figref>, an annular surface 112 positioned on inner roller 78 between segments 94 and 96 cooperates with an annular surface 114 positioned on outer roller 80 between segments 104 and 106 to form the first side surface 36 of the groove 24. Annular surface 114 can be considered part of segment 106 and, in this example, is oriented substantially perpendicularly to the axis of rotation 88 of the outer roller 80. Additionally, an annular surface 116 positioned on outer roller 80 between segments 106 and 108 cooperates with an annular surface 118 positioned on inner roller 78 between segments 96 and 98 to form the second side surface 38 of groove 24. Annular surface 116 may also be considered part of segment 106, and is angularly oriented with respect to axis 88. Orientation angles 120 may range from about 40° to about 70° or from about 45° to about 65° or may be at about 55°. In the example shown the annular surfaces on the inner roller 78 will have substantially the same orientation as the annular surface on the outer roller 80 with which they cooperate, however, other configurations are of course feasible. Proper alignment between the rollers 78 and 80 and their respective segments and annular surfaces is established and maintained by a flange 122, which, in this example, extends radially outwardly from the inner roller 78 and engages a groove 124 in the outer roller 80 when the outer roller 80 is moved towards the inner roller 78 to compress the pipe element between them during cold working.

<figref idref="f0010 f0011 f0012">Figures 9-11</figref> illustrate an example method of roll forming a pipe element 10 to impart the sidewall shape as shown in <figref idref="f0001">Figure 1</figref>. As shown in <figref idref="f0010">Figure 9</figref>, pipe element 10 is supported on inner roller 78 with its inner surface 126 contacting at least two of the segments 94, 98 and 102 at respective contact points 128, 129 and 130. For relatively short pipe elements, contact may be at 128, 129 and 130 or at any two of the three. For longer pipe elements contact will be at 128 and may be at 129 and 130. Outer roller 80 is moved toward the inner roller 78 and contacts the outer surface 132 of pipe element 10 with segment 106. Flange 122 on inner roller 78 acts as a stop to properly position the pipe element axially on the rollers. Once both the inner and outer rollers 78 and 80 are in contact with the pipe element 10 the inner roller is rotated about axis 82 by rotating means 84. This causes pipe element 10 to rotate in the same direction as the inner roller 78, and the outer roller 80 to rotate in the opposite direction about its axis 88. While it is advantageous to rotate the inner roller and move the outer roller toward it, it is understood that other combinations of rotating and moving the rollers are also feasible. It is further practical to hold the pipe element fixed and stationary and move the machine around the pipe element's longitudinal axis while compressing the pipe element sidewall between two rollers. In this case both of the rollers may be idlers, i.e. not powered in rotation, but rotate as a result of friction between the rollers and the pipe element.

As shown in <figref idref="f0011">Figure 10</figref>, outer roller 80 is moved toward the inner roller 78 to compress the pipe element between the rollers while the rollers are rotating. The pipe element sidewall 134 is thereby deformed through contact between the pipe element inner surface 126 and segments 94 and 98 of inner roller 78, and segments 106 and 110 of outer roller 80. This action begins to form the shoulder 22, the groove 24 and bead 26 in the sidewall 134. The rollers and pipe element continue to rotate, and, as shown in <figref idref="f0012">Figure 11</figref>, the outer roller 80 is moved further towards inner roller 78 to further compress the sidewall 134. Sidewall 134 is compressed between segments 94 and 104 to form the shoulder 22, the compressive force between the segments thinning the sidewall over the region of the shoulder 22 and enlarging its diameter to a desired final outer diameter 30 as shown in <figref idref="f0001">Figure 1</figref>. Sidewall 134 is also compressed between segments 96 and 106 to establish the final dimensions of the groove floor 42, including its outer diameter 44 shown in <figref idref="f0001">Figure 1</figref>. In certain embodiments, the sidewall 134 is also compressed between segments 96 and 106 to establish the inner diameter 17 of the portion of the pipe element 10 comprising the groove 24 to be approximately equal to the pipe inner diameter 19 (which is not compressed between the rollers) as shown in <figref idref="f0001">Figure 1</figref>. As further shown with respect to <figref idref="f0012">Figure 11</figref>, the sidewall 134 is compressed between annular surface 116 and the annular surface 118 to form the second side surface 38 of the groove 24 (the first side surface having been formed by cooperation between annular surfaces 112 and 114). Segment 110 also contacts the outer surface 132 of the pipe element 10 to assist in forming the bead 26.