Spin forming method and device

0001(Citation of related application) This application claims the benefit of priority on the basis of US Provisional Patent Application No. 61 / 530,771 (filed September 2, 2011). The application is hereby incorporated by reference in its entirety.

0002(Field of invention) The present invention relates to a method of spin-forming a pipe element to create shoulders, grooves, and beads in close proximity to its ends.

0003Various challenges are encountered when designing pipe elements that are joined by mechanical pipe couplers. Such couplers include two or more coupler compartments that are joined in an end-to-end relationship by threaded fasteners, examples of which are disclosed and referenced herein by reference. Be incorporated. The compartment surrounds the central space that receives the pipe elements. Each compartment has a pair of arched surfaces known as "keys" that engage the outer surfaces of the pipe element, which are often received in the circumferential groove of the pipe element and added to the joint. Provides beneficial mechanical engagement for bending and axial loads. Each compartment also defines a channel between its pair of arched surfaces that receives the ring-shaped gasket. Gaskets are typically compressed between the compartment and the pipe element, resulting in a liquidtight bond.

0004Circumferential grooves are advantageously formed by cold working the side walls of the pipe element. This is because, unlike cutting grooves, the material is not removed from the pipe sidewalls, and therefore thinner walled pipe elements can be grooved by the cold working process. For high pressure and / or high load applications, it is advantageous to use thinner wall pipe elements to save weight and cost. However, prior art cold working methods and pipe designs have coupler and pipe element engagement features that are suitable for high loads and pressures that can withstand the equivalent cutting groove system used for thicker wall pipe elements. Does not bring. The thin wall grooved pipe element is joined by a mechanical coupler and brought about through improvements to the design and manufacture of the thin wall grooved pipe element by cold working, which allows it to be used in high pressure / heavy load applications. There are clear advantages.

<p num="0005"><patcit num="1"><text>U.S. Pat. No. 7,712,796</text></patcit></p>

<p num="0006"> The present invention relates to a method of forming a groove on the outer surface of a pipe element. In one exemplary embodiment, the method Capturing the ends of the pipe elements in a die with first and second circumferential recesses that are spaced apart from each other. By inserting the mandrel into the pipe element, the mandrel is a first circular rib aligned with the first circumferential recess and a second circle aligned with the second circumferential recess. Having a circumferential rib, Rotating the mandrel in a trajectory centered on the longitudinal axis of the die, Increasing the diameter of the orbit while rotating the mandrel so that it pushes the mandrel against the inner surface of the pipe element, Tightening the pipe element between the first circumferential rib and the first circumferential recess, thereby rotating between the first and second circumferential recesses, rotating the mandrel in an orbit of increasing diameter. To part of the pipe element in the radial direction away from the die, thereby forming a groove The groove has an outer diameter smaller than the outer diameter of the rest of the pipe element.</p><p num="0007"> In this exemplary embodiment, the first circumferential recess is located on the first side surface, which is located close to the second circumferential recess, and distal to the second circumferential recess. It has a second side that is The floor extends between the first and second sides. An exemplary method may further include tightening the pipe element between the first circumferential rib and the first side surface.</p><p num="0008"> The first side surface can be oriented at the first orientation angle and the second side surface can be oriented at the second orientation angle. The first orientation angle can be less than the second orientation angle when measured with respect to a reference line extending perpendicular to the longitudinal axis of the die.</p><p num="0009"> In certain exemplary embodiments, the first circumferential rib comprises first and second flanks located on either side of the rib. The first flank faces the first flank and the second flank faces the second flank. In this exemplary embodiment, the pipe element is fastened between the first flank and the first side surface. At least the first flank can be angularly oriented with respect to a reference line extending perpendicular to the longitudinal axis of the die.</p><p num="0010"> In an exemplary embodiment, the second circumferential recess comprises a side surface located close to the first circumferential recess and a floor surface continuous with the side surface of the second circumferential recess. obtain. An exemplary method may further include tightening the pipe element between the second circumferential rib and the side surface of the second circumferential recess. The sides of the second circumferential recess can be substantially oriented perpendicular to the longitudinal axis of the die.</p><p num="0011"> In another exemplary embodiment, the second circumferential rib may include a flank facing the side of the second circumferential recess. In this exemplary embodiment, the method further comprises tightening the pipe element between the flank of the second circumferential rib and the side surface of the second circumferential recess. The flank of the second circumferential rib can be angularly oriented with respect to a reference line extending perpendicular to the longitudinal axis of the die.</p><p num="0012"> The method according to the invention may further include, by way of example, forming a shoulder at the end of the pipe element by pushing the second circumferential rib towards the second circumferential recess. In addition, the method may further include forming a bead within the pipe element adjacent to the groove by pushing the first circumferential rib towards the first circumferential recess.</p><p num="0013"> In another exemplary embodiment, the method comprises forming beads, grooves, and shoulders on the outer surface of the pipe element. In one exemplary embodiment, the method Capturing the ends of the pipe elements in a die with first and second circumferential recesses that are spaced apart from each other. By inserting the mandrel into the pipe element, the mandrel is a first circular rib aligned with the first circumferential recess and a second circle aligned with the second circumferential recess. Having a circumferential rib, Rotating the mandrel in a trajectory centered on the longitudinal axis of the die, Increasing the diameter of the orbit while rotating the mandrel so that it pushes the mandrel against the inner surface of the pipe element, Forming a bead by pushing the first circumferential rib toward the first circumferential recess, By pushing the second circumferential rib toward the second circumferential recess, the shoulder is formed and Tightening the pipe element between the first circumferential rib and the first circumferential recess, thereby rotating between the first and second circumferential recesses, rotating the mandrel in an orbit of increasing diameter. A groove is formed between the bead and the shoulder by moving a part of the pipe element in the radial direction away from the die, thereby forming a groove. The groove has an outer diameter smaller than the outer diameter of the rest of the pipe element.</p>

0014<figref num="1">FIG. 1 is a vertical cross-sectional view of an exemplary pipe element formed by the spin forming process according to the present invention.</figref><figref num="2">FIG. 2 is an isometric view of a valve, including exemplary pipe elements, formed by the spin forming process according to the invention.</figref><figref num="3">FIG. 3 is an exploded isometric view of the combination of pipe elements and pipe couplers.</figref><figref num="3A">3A and 3B are elevation views of the pipe coupler embodiment.</figref><figref num="3B">3A and 3B are elevation views of the pipe coupler embodiment.</figref><figref num="4">Figure 4-6 is a vertical cross-sectional view of the combination of pipe elements and pipe couplers.</figref><figref num="5">Figure 4-6 is a vertical cross-sectional view of the combination of pipe elements and pipe couplers.</figref><figref num="6">Figure 4-6 is a vertical cross-sectional view of the combination of pipe elements and pipe couplers.</figref><figref num="7">FIG. 7 is a schematic diagram of an exemplary spin forming machine for manufacturing pipe elements using the spin forming method.</figref><figref num="8">FIG. 8 is a schematic end-view of the spin forming machine shown in FIG.</figref><figref num="9">FIG. 9-11 is a vertical cross-sectional view illustrating an exemplary method of spin forming a pipe element.</figref><figref num="10">FIG. 9-11 is a vertical cross-sectional view illustrating an exemplary method of spin forming a pipe element.</figref><figref num="11">FIG. 9-11 is a vertical cross-sectional view illustrating an exemplary method of spin forming a pipe element.</figref><figref num="12">FIG. 12-15 is a vertical cross-sectional view illustrating in detail an exemplary method of spin formation.</figref><figref num="13">FIG. 12-15 is a vertical cross-sectional view illustrating in detail an exemplary method of spin formation.</figref><figref num="14">FIG. 12-15 is a vertical cross-sectional view illustrating in detail an exemplary method of spin formation.</figref><figref num="15">FIG. 12-15 is a vertical cross-sectional view illustrating in detail an exemplary method of spin formation.</figref>

0015The present invention relates to pipe elements, combinations of pipe elements and couplers, and methods and devices for cold working pipe elements to receive couplers and form liquidtight couplings. Throughout this book, the term "pipe element" refers to, for example, the pipe stock 10 as shown in FIG. 1 and the tubular portion 12 of a fluid handling or control component such as the valve 14 shown in FIG. Means any tubular structure, including. Other components such as pumps and filters, as well as fittings such as T-tubes, L-shaped fittings, curved pipes, and different diameter fittings, also have "pipe elements" as defined herein. Or included as a provision.

0016As shown in FIG. 1, the pipe element 10 has an outer diameter 16 that passes through a point on the longitudinal axis 18 at the center of curvature of the pipe element. At least one end 20 of the pipe element 10 is configured to receive a key (not shown) for the mechanical coupler, which configuration is adjacent to the shoulder 22 located at the end 20 and adjacent to the shoulder 22. It is provided with a groove 24 that is positioned in the groove 24 and a bead 26 that is positioned continuously with the groove 24.

0017As illustrated in detail in FIG. 1, the shoulder portion 22 has a surface 28 that extends circumferentially around the pipe element and faces outward. The surface 28 has an outer diameter 30 that is larger than the outer diameter 16 of the pipe element 10, excluding the shoulders. The shoulder 30 also has an outwardly facing curved surface 32. The 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 FIG. 1, the axis 34 is shown perpendicular to the visual plane so that the ends are visible forward.

0018The groove 24 is defined by a first side surface 36 that is positioned contiguously with the curved surface 32 of the shoulder 30. The side surface 36 is substantially oriented perpendicular to the longitudinal axis 18 in this exemplary embodiment, but can also be angularly oriented in other embodiments. "Substantially vertical", as used herein, may not be exactly vertical, but is established as close as practicable in terms of manufacturing practice and tolerance. Refers to angular orientation. The vertical orientation of the first side surface 36 helps to stiffen the pipe element in the radial direction and maintain its roundness.

0019The second side surface 38 further defines the groove 24. The second side surface 38 is positioned in a separated relationship from the first side surface 36 and is angularly oriented with respect to the longitudinal axis 18. The side surface 38 can have an orientation angle 40 of about 40 ° to about 70 ° or about 45 ° to about 65 °. In the particular embodiment shown in FIG. 1, the orientation angle 40 is about 55 ° and is considered advantageous if the groove receives the key of the mechanical coupler, as shown in FIG. 3-6. Be done.

0020The floor surface 42 extends between the first side surface 36 and the second side surface 38 of the groove 24. In the exemplary embodiment shown, the floor surface 42 is substantially parallel to the longitudinal axis 18 and has an outer diameter 44 smaller than the outer diameter 16 of the pipe element excluding the groove. The groove 24 also has an inner diameter 17 that is approximately equal to the inner diameter 19 of the pipe element 10 in the embodiment shown in FIG.

0021The bead 26 is positioned continuously with the second side surface 38 of the groove 24 and extends circumferentially around the pipe element. The bead 26 projects outwardly away from the shaft 18 and has a vertex 46 with an outer diameter 48 greater than the outer diameter 16 of the pipe element excluding the bead. In the exemplary embodiment shown in FIG. 1, the diameter 48 of the apex 46 is smaller than the outer diameter 30 of the shoulder 22. The bead 26 increases the radial stiffness of the pipe element, thereby helping to maintain its roundness.

0022For pipe stock, the configuration of the ends of pipe element 10 (shoulder 22, groove 24, and bead 26) is the same at both ends (not shown for clarity), but other ends may differ. Configuration is also possible. In addition, the pipe element 50 at the opposite end of the valve 14 also has the end configuration described above, with the valve or any other fluid control component or fitting using a mechanical coupler to make other pipes. Allowed to be joined to the element, examples of which are shown in Figures 3, 3A, and 3B. Alternatively, valves and other fluid control components and fittings may also have different end configurations.

0023In one embodiment illustrated in FIG. 3, the mechanical coupler 52 comprises, in this embodiment, two or more compartments 54 attached to each other in an end-to-end relationship by a threaded fastener 56. The compartment 54 encloses a central space 58 that receives the pipe elements 10 and joins them in a liquidtight junction. The elastomer gasket 60 is captured between the compartments 54 and engages the outward facing surface 28 of the shoulder portion 24, the elastomer gasket 60 having an inward facing sealed surface 62 that ensures liquid tightness. Each compartment has a pair of arched surfaces or keys 64 that project inward towards the central space and are received within the groove 24 of the pipe element 10.

0024In another embodiment shown in FIG. 3A, the coupler 53 comprises a single compartment formed from an integrated body 55 having ends 57 and 59 in distant opposition. Bolt pads 61 extend from the ends 57 and 59, and fasteners 63 extend between the bolt pads to pull them together as the fasteners are tightened. The integrated body surrounds the central space 65 that receives the pipe elements and forms the joint. The keys 67, which are separated from each other on both sides of the coupler 53, extend in the circumferential direction along the integrated main body 55 and project inward in the radial direction. A gasket 60 similar to the one described above is positioned between the keys. Tightening the fastener 63 pulls the key 67 into engagement with the groove in the pipe element and compresses the gasket 60 between the integrated body 55 and the pipe element.

0025FIG. 3B shows another coupler embodiment 69 formed from two compartments 71 and 73 joined at one end by a hinge 75. The opposite ends 77 and 79 of the compartment are spaced apart and opposed and connected by a fastener 81. The compartments 71 and 73 also have a circumferential key 83 that is spaced apart, with the gasket 60 positioned between them. The compartment surrounds the central space 65, which receives the pipe elements and forms a junction. Tightening the fastener 81 pulls the key 83 into engagement with the groove in the pipe element and compresses the gasket 60 between the compartment and the pipe element.

0026The joint can be formed between the two pipe elements 10 by first disassembling the coupler 52 (see FIG. 3) and sliding the gasket 60 over one end of the pipe element. The ends of the other pipe elements are then aligned close to the ends of the first pipe element, the gasket is positioned to close the gap between the ends of the two pipe elements, and the sealing surface of the gasket. 62 engages the respective outer surface 28 of the shoulder 24 of each pipe element. The coupler compartment 54 is then positioned around the gasket 60 and the ends of the pipe elements, and the key 64 is aligned with the respective groove 24 of each pipe element. Fasteners 56 then apply to compress the gasket 60 against the pipe element to pull the compartments towards each other, engage the keys 64 into their respective grooves 24, and form a liquidtight bond. And tightened.

0027In an alternative embodiment, FIG. 4-6 details the engagement of the pipe element 10 with a coupler 52 of the type that is easy to install, the compartments 54 are pre-assembled and by fasteners 56 each other. Retained in a spaced relationship, the compartment is supported on the gasket 60. The compartments are sufficiently spaced so that the pipe elements 10 can be inserted into the central space 58 without disassembling the coupler, as shown in FIGS. 4 and 5. Note that the outward facing surface 28 of the shoulder 22 engages the sealing surface 62 of the gasket 60 and the key 64 is aligned with each groove 24 of the pipe element. As shown in FIG. 6, fasteners 56 (see FIG. 1) that join the compartments 54 to each other are tightened and pull the compartments towards each other. This compresses the gasket 60 against the pipe element, providing a seal, pushing the key 64 into the groove 24, providing a beneficial mechanical connection between the coupler and the pipe element 10, resulting in a joint. In one embodiment detailed in FIG. 6, the key 64 has a cross-sectional shape that is compatible with the groove, and the key has a substantially vertical key surface 66 that engages the first side surface 36 of the groove. The mated, angle-oriented key surface 68 has dimensions for engaging the angle-oriented second side surface 38 of the groove. The surfaces 68 and 38 have complementary orientation angles, which is advantageous for maximizing surface-to-surface contact. In general, for this embodiment, there will be a gap 70 between the groove floor surface 42 and the radially facing surface 72 of the key 64. This is due to tolerance fluctuations in both the pipe element and the coupler. Some clearance between the surfaces 42 and 72 is advantageous to ensure that the key engages the groove by wedge action, which provides rigidity to the joint, axial compression and tension. Keep the pipe elements separated from each other under load. The formation of the joint using coupler embodiments 53 and 69 shown in FIGS. 3A and 3B proceeds in the same manner as described above for the easy-to-install embodiment. For example, only the vertical key surface 66 touches the first side surface 36 of the groove, or only the key surface 68 that is angle oriented is the groove 24. Other embodiments in contact with the second side surface 38 are also possible. It is also possible for the coupler compartment to float on the gasket 60, and none of the key surfaces will come into contact with the groove surface, at least initially, until the junction is loaded.

0028It is advantageous to use spin forming techniques to form circumferential shoulders, grooves, and beads. Spin formation uses a fixed outer die and a roller tool or "mandrel" that rotates in orbit within the die. The pipe element is held in the die between the die and the mandrel, and the mandrel orbits around the longitudinal axis of the die. The mandrel trajectory is increased in diameter and the mandrel is pushed against the inner surface of the pipe element. As the mandrel rotates, it pushes the ends of the pipe elements to match the shape to the mandrel and die shapes.

0029Spin formation is advantageous because it eliminates the process's sensitivity to changes in pipe element outer diameter tolerance. Techniques such as roll formation can be used to cold work the pipe element to produce the desired shoulder-bead-groove shape, but to an acceptable degree due to variations in the outer diameter of the pipe element. Establishing shoulder and groove outer diameters with reproducibility is difficult. However, by using spin formation with its fixed outer die, the dimensional variation of the pipe element outer diameter is due to the fact that the outer die reliably establishes the outer surface dimension of the pipe element, regardless of the initial diameter of the pipe element. unrelated.

0030Figures 7 and 8 graphically depict the exemplary spin forming machine 136. As shown in FIG. 8, machine 136 includes dies 138 formed in four compartments 140, 142, 144, and 146. The die compartments are mounted within bearings (not shown) and are slidably movable towards and away from each other using the respective actuators 148, 150, 152, and 154. In this embodiment, there are four die compartments consisting of offset pairs (140 and 142, 144, and 146), but dies with only two compartments are also possible. As shown in FIG. 7, the mandrel 156, which is a spin forming tool, is mounted in the housing 158. The housing 158 has a fixed rotating shaft 160 and is mounted on a carrier 162 that moves along a guide rod 164 toward and away from the die 138. Actuator 166 brings the movement of the carrier 162, and thus the mandrel 156, towards and away from the die. The housing 158 is similarly driven on the bearing 168 by an electric motor 170 mounted on the carrier in rotation about the shaft 160 with respect to the carrier 162. The axis of rotation 160 of the housing 158 is substantially parallel to the longitudinal axis 161 of the die, as best seen when the die compartments 140, 142, 144, and 146 are put together. However, the mandrel 156 can be moved relative to the housing 158 in a direction that offsets its longitudinal axis 172 from the rotation axis 160 of the housing. The offset movement of the mandrel 156 is via an actuator 174 mounted on the housing 158. The spring 176 provides a restoring force that returns the mandrel longitudinal axis 172 back to coaxial alignment with the housing rotation axis 160 when the force of the actuator 174 is relaxed.

0031As shown in FIG. 9, the die compartment (140 shown) has an inner surface 178 that is shaped to produce the desired final shape of the outer surface 134a of the pipe element 134 during spin formation. Further, the mandrel 156 wants the outer surface 134a of the pipe element 134 to be defined by the inner surface 178 of the die 138 when the outer surface 180 of the mandrel 156 is pushed against the inner surface 134b of the pipe element 134 during the spin forming process. In cooperation with the inner surface 178 of the die compartment to take shape, the material of the pipe element 134 has an outer surface 180 formed to allow it to deform and flow.

0032In operation, actuators 148 and 150 move the respective die compartments 140 and 142 away from each other, as illustrated in Figure 7-11. Similarly, actuators 152 and 154 move the respective die compartments 144 and 146 away from each other, thereby opening the die 138. The pipe element 134 can then be inserted into the die. As shown in FIG. 9, the die 138 then uses their respective actuators to bring the respective die compartments 140 and 142, 144, and 146 together to capture the end of the pipe element 134. Closed by. The actuator 166 then moves the carrier 162 toward the die 138, as shown in FIGS. 7 and 9. The mandrel 156 has its longitudinal axis 172 coaxially aligned with the rotation axis 160 of the housing 158 at this point, and thus also the longitudinal axis 161 defined by the die 138 and the longitudinal axis 182 of the pipe element 134. Both are coaxially aligned and positioned and moved towards die 138. The mandrel 156 is inserted into the pipe element 134 captured by the die. The housing 158 is then rotated by the motor 170 about its rotation axis 160, and the actuator 174 moves the longitudinal axis 172 of the mandrel 156 so that it is out of coaxial alignment with the longitudinal axis 160 of the housing. .. This configuration is shown in FIG. 10, where the mandrel 156 axis 172 is also offset from the longitudinal axis 182 and die axis 161 of the pipe element 134. This eccentric configuration rotates the mandrel 156 around the longitudinal axis 161 of the die 138 and the longitudinal axis of the pipe element 134 in a circular orbit in response to the rotation of the housing 158. The diameter of the orbit increases as the actuator 174 continuously moves the mandrel 156 further off the axis 160 of the housing 158. The continuous movement of the mandrel 156 with respect to the housing 158 while the housing is rotating pushes the mandrel against the inner surface 134b of the pipe element 134. I will. As shown in FIG. 11, the mandrel 156 travels around the inner surface of the pipe element in its orbit, cold-working the material, and substantially transforms the outer surface 134a of the pipe element 134 into the shape of the inner surface 178 of the die 138. Press to match. In this embodiment, shoulders 22, grooves 24, and beads 26 are formed. However, it is also possible to form only the shoulders and grooves, or only the beads and grooves, depending on the shape of the die and mandrel. Note that the mandrel is free to rotate about its longitudinal axis 172 in order to reduce friction between the mandrel 156 and the inner surface 134b of the pipe element 134. When the desired shoulder-bead-groove shape is achieved upon completion of the spin forming process, the rotation of the housing 158 is stopped and the longitudinal axis 172 of the mandrel 156 becomes the housing longitudinal axis 160 and Returned to alignment with the die shaft 161, the carrier 162 is moved away from the die 138, thereby removing the mandrel 156 from within the pipe element 134. The die 138 is then opened by moving the die compartments 140, 142, 144, and 146 apart, thereby allowing the formed pipe element to be removed from the die. Returned to alignment with, the carrier 162 is moved away from the die 138, thereby removing the mandrel 156 from within the pipe element 134. The die 138 is then opened by moving the die compartments 140, 142, 144, and 146 apart, thereby allowing the formed pipe element to be removed from the die. Returned to alignment with, the carrier 162 is moved away from the die 138, thereby removing the mandrel 156 from within the pipe element 134. The die 138 is then opened by moving the die compartments 140, 142, 144, and 146 apart, thereby allowing the formed pipe element to be removed from the die.

0033FIG. 12-15 details an exemplary method for spin-forming the groove 24 and the shoulder 22 and bead 26 within the pipe element 134. As shown in FIG. 12, the mandrel 156, which travels its eccentric trajectory of increasing diameter around the die longitudinal axis 161 is shown in contact with the inner surface 134b of the pipe element 134. In this embodiment, the die 138 has first and second circumferential recesses 192 and 194 that are spaced apart from each other. The mandrel 156 has first and second circumferential ribs 196 and 198. Note that the first rib 196 is aligned with the first recess 192 and the second rib 198 is aligned with the second recess 194 as the mandrel 156 is inserted into the pipe element 134. I want to.

0034As shown in FIG. 13, the first recess 192 has a first side surface 200 located close to the second recess 194 and a second recess located distal to the second recess 194. Defined by a side surface 202 of the floor surface 204 extending between the first and second side surfaces 200 and 202. Note that in this example, the first and second sides are angularly oriented with respect to the respective reference lines 206 and 208 extending perpendicular to the die axis 161. In some embodiments, the orientation angle 210 of the first side surface is smaller than the orientation angle 212 of the second side surface 202 (as shown). The orientation angle 210 of the first side surface 200 can be in the range of about 20 ° to about 50 °, and the orientation angle 212 of the second side surface 202 can be in the range of about 20 ° to about 75 °.

0035The first rib 196 comprises first and second flanks 214, 216 located on either side of the rib. The first flank 214 faces the first side surface 200 of the first recess 192, and the second flank 216 faces the second side 202. The first and second flanks 214 and 216 are angularly oriented with respect to their respective reference lines 218 and 220 extending perpendicular to the die axis 161. The orientation angle 222 of the first flank 214 can range from about 10 ° to about 55 °, and the orientation angle 224 of the second flank 216 can range from about 10 ° to about 75 °.

0036In this exemplary embodiment, the second recess 194 is defined by a side surface 226 located close to the first recess 192 and a floor surface 228 continuous with the side surface 226. In this embodiment, the side surface 226 is substantially oriented perpendicular to the die axis 161 but can also be angularly oriented. Side 226 and floor 228 work together to define shoulder 22 (see Figures 13 and 14).

0037The second rib 198 includes a flank 230, which is positioned to face the side surface 226 of the second recess 194. The flank 230 can be angularly oriented with respect to a reference line 232 extending perpendicular to the die axis 161 as shown. The orientation angle 234 of the flank 230 can range from about 1 ° to about 45 °.

0038Referring to FIG. 14, as the mandrel 156 rotates in its orbit of increasing diameter, the pipe element 134 is of the first flank 214 of the first circumferential rib 196 and the first recess 192. Tightened to and from the first side surface 200. When this tightening is brought about, it is observed that the groove 24 is formed on the outer surface 134a of the pipe element 134, and the portion 134c of the pipe element is with the floor 42 and the die 138 of the groove 24, as shown in FIG. Move away from the die 138 inward in the radial direction, as evidenced by the gap 184 between them. Also, as shown in FIG. 14, further tightening of the pipe element 134 occurs between the flank 230 of the second circumferential rib 198 and the side surface 226 of the second recess 194, which is a die. It is believed that it contributes to the formation of the groove 24 by facilitating the movement of the radial inward portion 134c away from 138. As shown in FIG. 11, the groove 24 so formed within the pipe element 134 has an outer diameter 186 that is smaller than the outer diameter 188 of the rest of the pipe element. In this exemplary method, the shoulder 22 and bead 26 further have a second circumferential rib 198 towards the second circumferential recess 194 and a first, respectively, as shown in FIG. It is formed by pushing the circumferential rib 196 toward the first circumferential recess 192.

0039The radial inward movement of the region 134c of the pipe element 134 to form the gap 184 away from the die 138 is in contrast to the radial outward movement of the mandrel 156 and is therefore unexpected. The method allows the pipe element 134 to be formed (as shown in FIG. 11), the outer surface 134a of the groove 24 having a diameter 186 less than the diameter 188 of the outer surface of the rest of the pipe element. That is, the outer surface 134a of the pipe element is dedicated to the groove 24. Previously, such a configuration was thought to be possible only by the roller formation of the pipe element between the two rotating rollers, but the spin formation according to the invention is of a fixed die that captures the pipe element. The effect allows this configuration to be achieved while maintaining the precise and reproducible outer dimensions of the pipe element. This was because it was thought that spin formation could only extend the pipe element (ie, any part of the pipe element deformed by spin formation must have a diameter greater than its original dimensions). , Unexpected. Therefore, according to conventional wisdom, in the spin forming process, it is not possible to start with a pipe element having a first outer diameter and end with a part of a pipe element having a second outer diameter smaller than the first outer diameter. Although not possible, the applicant achieves this by using spin formation in the method according to the invention.

0040Pipe element configurations with shoulders, grooves, and beads, as well as methods and devices for creating configurations as illustrated and described herein, are thin-walled pipe elements joined by mechanical couplers. Allows for use in high pressure / heavy load applications previously considered unsuitable for thin wall pipe elements and grooved mechanical couplers. Various additional advantages over prior art pipe elements are also realized. For example, the outer diameter 186 of the groove bed 42 is known to be an important dimensional parameter for compatibility between the coupler and the pipe element in terms of pipe element diameter manufacturing tolerance. The spin forming method disclosed herein allows this parameter to be controlled so that a groove compatible with the coupler can be formed in both the maximum and minimum pipe diameter tolerances. In addition, a combination of an enlarged shoulder diameter of 190 (outward facing surface of the shoulder 22 larger than the pipe element outer diameter) and a reduced groove diameter (groove 42 outer diameter smaller than the pipe element outer diameter). Allows lighter couplers to be used without adverse performance conditions. Also, the tighter tolerance that groove and shoulder dimensions can be retained makes it easier to design the coupler. Practically, this leads to lower cost couplers in lighter and stronger joints that can withstand higher internal pressures. Gasket design is also simplified due to tighter tolerances allowed, through which the gasket can be extruded and expanded under high pressure, formed between coupler compartments, control of gap size. It's easier. Manufacturing advantages are also ensured as less thinning and less cold working of the pipe element is required, which means lower residual stress, higher elongation residuals, and stronger pipe element. To do. The addition of the bead 26 provides a stiffer, less bendable joint, allowing the key to fill the groove and advantageously employ a wedge action. Wedge action, for example, due to heat load or vertical pipe stacking, odors at a constant distance even under axial compression. And hold the pipe element in the coupler. This prevents the pipe element, if present, from tightening and damaging the gasket center leg. The enlarged shoulder also allows the groove to be relatively shallow and exhibit a thinner internal contour within the pipe element. The thinner contour groove at each junction results in less head loss and less turbulence in the fluid flowing through the pipe element. In addition, the groove is formed concentrically with the shoulder to achieve a more uniform engagement between the coupler and the pipe element, further reducing the possibility of leakage.