Tube grooving device with flaring cup

Abstract

A pipe grooving apparatus has a flaring cup surrounding a pipe end stop. The cup and pipe end stop are mounted on a fixed pinion gear about which a carriage rotates. The carriage carries a geared cam which engages and rotates synchronously with the pinion gear as the carriage rotates relative to the pinion gear. The cam engages a pipe element received by the cup and forms a circumferential groove in the pipe element. The cup and pipe stop move axially along the pinion gear shaft independently of each other to actuate rotation of the carriage. The flaring cup accommodates pipe diameter dimensional tolerances and reduces pipe flaring and maintains pipe roundness during the grooving process.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is based upon and claims the benefit of priority to U.S. Provisional Application No. 62 / 889,671, filed on August 21, 2019, which is hereby incorporated herein by reference. Technical Field

[0003] The present invention relates to a machine for cold working tubular components using a cam. Background Art

[0004] Cold working of the pipe element (e.g., stamping a circumferential groove in the pipe element to accept a mechanical pipe coupling) is advantageously accomplished using a roller slotting machine having an inner roller that engages the inner surface of the pipe element and an outer roller that simultaneously engages the outer surface of the pipe element. As the pipe is rotated about its longitudinal axis, typically by driving the inner roller, the outer roller is gradually pushed toward the inner roller. The roller has a surface profile that is stamped onto the circumference of the pipe element as it rotates to form the circumferential groove.

[0005] This technology faces various challenges if the pipe element is to be cold worked to the necessary accuracy with the required tolerance. The most pressing is the difficulty associated with producing a groove of the desired radius (measured from the center of the pipe element hole to the bottom of the groove) within the desired tolerance range. In addition, stamping a circumferential groove near the end of the pipe element generally causes the end area of ​​the pipe element to expand in diameter, a phenomenon known as "flaring". Flaring and pipe element tolerances must be considered in the design of mechanical couplings and seals, and this complicates their design and manufacture. These considerations have led to complex prior art devices, which, for example, require an actuator to force the roller to engage the pipe element and require the operator to adjust the roller stroke to achieve the desired groove radius. In addition, the prior art roller groover applies significant torque to the pipe element and has a low productivity, typically requiring the pipe element to rotate many times to obtain a completed circumferential groove. It is clear that such a device is needed, which, for example, uses a cam to accurately cold work the pipe element, which is simple, but produces faster results and has less operator involvement. Summary of the invention

[0006] The present invention relates to a device for forming a circumferential groove in a tubular element. In an exemplary embodiment, the device includes a pinion that is fixed to prevent rotation about a pinion axis arranged coaxially with the pinion. A bracket surrounds the pinion. The bracket is rotatable about the pinion axis and defines an opening for receiving the tubular element arranged coaxially with the pinion axis. A cup is positioned near the pinion. The cup has a side wall arranged coaxially with the pinion axis and defining an interior. The side wall has an inner surface. The inner surface has a first diameter located away from the pinion and a second diameter located near the pinion. The first diameter is greater than the second diameter. In a specific exemplary embodiment, the side wall may have a tapered inner surface. In an exemplary embodiment, the tapered inner surface may define an angle from 11° to 16°.

[0007] The interior faces an opening for receiving a tube element. The cup is movable toward and away from the pinion along the pinion axis. A tube end stop is positioned within the interior between the first and second diameters. The tube end stop is movable toward and away from the pinion along the pinion axis relative to the cup. A cup spring may act between the cup and the pinion to bias the cup away from the pinion. A retaining spring may act on the tube end stop and bias the tube end stop away from the pinion. A plurality of gears are mounted on a bracket. Each gear is rotatable about a corresponding gear axis relative to the bracket. At least one of the gears is directly engaged with the pinion. In an example embodiment, each gear is directly engaged with the pinion. A plurality of cam bodies are mounted on respective ones of the gears. A plurality of first cam surfaces extend around respective ones of the cam bodies and are engageable with a tube element received within the opening. Each of the first cam surfaces includes an area of ​​increased radius. Each of the first cam surfaces includes a first discontinuity of the first cam surface.

[0008] An example device according to the present invention may also include a pinion shaft. The pinion is fixedly mounted on the pinion shaft. The bracket is rotatably mounted on the pinion shaft. In an example embodiment, the pinion shaft defines a hole coaxially aligned with the pinion axis. The cup shaft can be positioned in the hole. The cup shaft is movable in the hole along the pinion axis. The first end of the cup shaft extends from the hole. The cup is mounted near the first end of the cup shaft. In an example embodiment, the cup includes a hub that coaxially receives the cup shaft. The rear wall extends outward from the hub. The side wall is attached to the rear wall.

[0009] In an example device according to the present invention, the tube end stop includes a sleeve fixedly mounted on a cup shaft. A plate mounted on the sleeve extends outwardly from the sleeve. The plate defines a tube engaging surface facing the opening. For example, the plate may also include a reverse tapered surface positioned within the tube engaging surface.

[0010] In another example, the cup may include a hub that coaxially receives the sleeve. The rear wall extends outwardly from the hub. The side wall is attached to the rear wall. An example device may also include a base and a post mounted on the base. The pinion shaft may be fixedly mounted on the post. In an example embodiment, the cup spring includes a conical spring.

[0011] In addition, as an example, each gear has the same pitch diameter. Also as an example, each of the first cam surfaces may include an area with a constant radius positioned adjacent to a corresponding one of the first discontinuities. In a specific example embodiment, each of the second cam surfaces includes an area with a constant radius positioned adjacent to a corresponding one of the second discontinuities. In addition, as an example, each of the second cam surfaces may have a constant radius.

[0012] In example embodiments, at least one traction surface extends around one of the cam bodies. The at least one traction surface has a gap therein. The gap is axially aligned with a first discontinuity of a first cam surface around one of the cam bodies. In specific example embodiments, at least one traction surface includes a plurality of protrusions extending outwardly therefrom. As another example, at least one traction surface is positioned proximate to the first cam surface around one of the cam bodies.

[0013] In an example embodiment, the pinion gear has a pitch diameter equal to the outer diameter of the tubular element.In another example embodiment, at least one traction surface has a pitch diameter equal to the pitch diameter of one of the gears.

[0014] An example device according to the present invention may also include a plurality of traction surfaces. Each of the traction surfaces extends around a corresponding one of the cam bodies. Each of the traction surfaces has a gap therein. Each gap is axially aligned with a corresponding one of the discontinuities of the first cam surface on each of the cam bodies. Each of the traction surfaces has a pitch diameter equal to the pitch diameter of the gear. In an example embodiment, at least one traction surface extends around one of the cam bodies. The at least one traction surface has a gap therein. The gap is axially aligned with a first discontinuity of the first cam surface around one of the cam bodies. Example embodiments may have a first cam surface positioned between at least one traction surface and a second cam surface around one of the cam bodies. Further, by way of example, the first and second cam surfaces may be positioned between at least one traction surface and a gear on which one of the cam bodies is mounted.

[0015] Example embodiments may also include a plurality of traction surfaces. Each of the traction surfaces extends around a corresponding one of the cam bodies. Each of the traction surfaces has a gap therein. Each gap is axially aligned with a corresponding one of the discontinuities of the first cam surface on each of the cam bodies. Each of the traction surfaces may have a pitch diameter equal to the pitch diameter of the gear. Further, as an example, each of the first cam surfaces may be positioned between a corresponding one of the traction surfaces and a corresponding one of the second cam surfaces on each cam body. In another example embodiment, each of the first and second cam surfaces may be positioned between a corresponding one of the traction surfaces and a corresponding one of the gears on each cam body. In a specific example, each of the first cam surfaces is positioned proximate to a corresponding one of the traction surfaces on each cam body. Example embodiments of the apparatus according to the present invention may include at least three gears or at least five gears. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a longitudinal cross-sectional view of an example apparatus for forming a circumferential groove in a tubular element;

[0017] Figure 1A yes Figure 1 a longitudinal cross-sectional view, on an enlarged scale, of a portion of the device shown;

[0018] Figure 2 It is a method of forming a circumferential groove in a pipe element. Figure 1 a longitudinal cross-sectional view of the device shown;

[0019] Figure 2A yes Figure 2 a longitudinal cross-sectional view, on an enlarged scale, of a portion of the device shown;

[0020] Figure 3 and Figure 3A yes Figure 1 an exploded isometric view of selected components of the illustrated device;

[0021] Figure 4 is Figure 1 An isometric view on an enlarged scale of an example cam used in the illustrated device;

[0022] Figure 5 is Figure 1 an end view, on an enlarged scale, of an example cam used in the illustrated apparatus;

[0023] Figure 6 is Figure 1 a side elevational view, on an enlarged scale, of an example cam used in the illustrated apparatus;

[0024] Figure 7 is Figure 1an isometric view of a gear reduction assembly used in the device shown;

[0025] Figure 8 is Figure 1 end views of selected components used in the illustrated apparatus;

[0026] Fig. 9 is a longitudinal cross-sectional view of an example apparatus for forming a circumferential groove in a tubular element;

[0027] Fig. 9A yes Fig. 9 a longitudinal cross-sectional view, on an enlarged scale, of a portion of the device shown;

[0028] Fig.10 It is a method of forming a circumferential groove in a pipe element. Fig. 9 a longitudinal cross-sectional view of the device shown;

[0029] Fig. 10A yes Fig.10 a longitudinal cross-sectional view, on an enlarged scale, of a portion of the device shown;

[0030] Fig.11 yes Fig. 9 an exploded isometric view of selected components of the illustrated device;

[0031] Fig.12 is Fig. 9 a side elevational view, on an enlarged scale, of an example cam used in the illustrated apparatus;

[0032] Fig.13 is Fig. 9 an end view, on an enlarged scale, of an example cam used in the illustrated apparatus;

[0033] Fig.14 is Fig. 9 end views of selected components used in the illustrated apparatus;

[0034] Fig.15 is an exploded isometric view of another exemplary embodiment of a portion of an apparatus for forming a circumferential groove in a tubular element according to the present invention;

[0035] Fig.16 yes Fig.15 a cross-sectional side view of the device shown;

[0036] Figures 17 to 19 yes Fig.15 a cross-sectional side view of the device shown, illustrating the operation of the device; and

[0037] Fig. 20 yes Fig.15 Front cross-sectional view of the device shown. DETAILED DESCRIPTION

[0038] Figure 1 and Figure 1A An example apparatus 10 for forming a circumferential groove in a tubular element is shown. The apparatus 10 is advantageous for grooving tubular elements having a nominal diameter of 1.25 inches or greater. The apparatus 10 includes a pinion 12 mounted on an intermediate shaft 14 (see also Figure 3 ). The pinion 12 and the intermediate shaft 14 are fixedly mounted to prevent rotation about a pinion axis 16 arranged coaxially with the pinion and the shaft. The rotational fixation of the pinion 12 is achieved by a key 18 between the pinion and the intermediate shaft 14 and by engaging a portion 14a of the intermediate shaft 14 with a fixed mount 20. The fixed mount 20 is fixedly mounted on a base 22. The portion 14a of the intermediate shaft 14 has a polygonal cross-section that engages an opening 24 extending through the fixed mount 20. The shape of the opening 24 matches the shape of the portion 14a of the intermediate shaft 14 and will therefore prevent the shaft from rotating about the pinion axis 16, but allow axial movement of the shaft. In this example embodiment, the portion 14a has a square cross-section and the opening 24 has a substantially matching square shape.

[0039] The carrier 26 surrounds the pinion 12. The carrier 26 is mounted on a flange 28 of an outer shaft 30. The outer shaft 30 is hollow, surrounds the intermediate shaft 14 and is coaxial with the intermediate shaft 14. A bearing 32 positioned between the outer shaft 30 and the intermediate shaft 14 allows the outer shaft and therefore the carrier 26 attached to the outer shaft to rotate relative to the intermediate shaft 14 about the pinion axis 16. The carrier 26 defines an opening 34 for receiving a tube element in which a groove is to be formed. The opening 34 is arranged coaxially with the pinion axis 16. A stop plate 36 is mounted on the intermediate shaft 14 via the pinion 12. The stop plate 36 is axially movable along the pinion axis 16 together with the intermediate shaft 14 and the pinion 12. The stop plate 36, the intermediate shaft 14 and the pinion 12 are biased toward the opening 34 by a spring 38 acting between the pinion and the outer shaft 30 via the shaft flange 28. Because the intermediate shaft 14 is rotationally fixed relative to the base 22, a thrust bearing 40 may be used between the pinion 12 and the spring 40 to protect the spring 38 which rotates with the flange 28 and the outer shaft 30 and to reduce friction between the pinion 12 and the flange 28. A stop plate 36 cooperates with the pinion 12 and the thrust bearing 40 to provide a positive locking stop which positions the tube element to achieve proper positioning of the groove.

[0040] A plurality of gears 42 are mounted on the bracket 26. Figure 1 , Figure 2 and Figure 3In the example embodiment shown, the carrier has four gears spaced at an angle of 90° from each other. Each gear 42 is rotatable about a respective gear axis 44. In a practical embodiment, each gear is mounted on a gear shaft 46, which is fixed between a front plate 48 and a rear plate 50 forming the carrier 26. Bearings 52 positioned between each gear 42 and its respective shaft 46 provide low friction rotation of the gear within the carrier 26. Each gear 42 engages with the pinion 12.

[0041] like Figure 4 As shown, a cam body 54 is mounted on each gear 42. A first cam surface 56 extends around each cam body 54. The first cam surface 56 can engage with a pipe element received through the opening 34. Figure 5 As shown, the first cam surfaces 56 include an area 58 of increased radius and a discontinuity 60 in the cam surface. The discontinuity 60 is a location where the cam surface 56 does not contact the cam body 54 of the tubular element. It is further advantageous to include as part of each first cam surface 56 an area 62 of constant radius located adjacent the discontinuity 60. At least one traction surface 64 may extend around one of the cam bodies 54. Figure 3 In the example shown, a corresponding traction surface 64 extends around each cam body 54. The traction surfaces 64 may also engage with a tubular element received within the bracket 26, but each traction surface has a gap 66 that is axially aligned (i.e., in a direction along the gear axis 44) with the discontinuity 60 in the first cam surface 56 on each cam body 54. Figure 4 As shown, the traction surface 64 may include a plurality of protrusions 68 extending outwardly therefrom. The protrusions provide grip between the tubular element and the traction surface 64 during operation of the device, and may be formed, for example, by embossing the traction surface. The traction surface has a pitch circle with a diameter 128. When the protrusions 68 are present on the traction surface 64, the pitch circle diameter 128 of the traction surface will be determined by the interaction of the protrusions 68 with the tubular element 79 (including the embossing performed by the protrusions 68 on the tubular element 79). If the protrusions 68 are not present, the pitch circle diameter 127 of the traction surface 64 will be equal to the pitch circle diameter of the traction surface. Figure 4 As further shown, the first cam surface 56 is positioned between the gear 42 and the traction surface 64 in spaced relationship from the traction surface but closer to the traction surface than the gear.

[0042] like Figure 1 and Figure 4As shown, the second cam surface 70 is also positioned on the cam body 54 and extends around it. The second cam surface 70 is a controlled flaring surface. Flaring is the radial expansion of the end of the pipe element that tends to occur when a circumferential groove is formed near the end. The second cam surface 70 (controlled flaring surface) is positioned near the gear 42 so that it contacts the pipe element near its end where flaring will be most significant due to the groove formation. Figure 4 and Figure 6 As shown, the second cam surface 70 has a constant radius 72 except for its discontinuity 70a, which is sized to engage with the tubular element to control flaring and, for example, to maintain its end at the original nominal diameter of the tubular element during and after groove formation. The discontinuity 70a is aligned with the discontinuity 60 in the first cam surface 56 and is a location on the cam body 54 where the cam surface 70 does not contact the tubular element. In alternative embodiments, the second cam surface 70 can have an area of ​​increased radius and a finish area of ​​constant radius, or the second cam surface 70 can have an increased radius over its entire arc length.

[0043] like Figure 1 , Figure 3 and Figure 3A As shown, the device 10 also includes an expansion die 74 positioned adjacent the pinion 12. In this example, the die 74 includes four segments 76 that are radially slidably mounted on the pinion 12 and coupled to an actuator. In this example, the actuator includes a pull rod 78 that extends through a hollow bore 80 of the intermediate shaft 14. The pull rod 78 has a tapered faceted end 82 that engages a mating faceted surface 84 on each die segment 76. The pull rod 78 is axially movable within the bore 80 relative to the intermediate shaft 14, and the die segments 76 are radially movable toward and away from the pinion axis 16 relative to the pinion 12. The radial movement of the die segments 76 is achieved by the axial movement of the pull rod 78. Figure 1 and Figure 1A The tie rod 78 and mold segment 76 are shown in a retracted position, and Figure 2 and Figure 2A The tie rod and mold segments are shown in an expanded position. When the tie rod 78 is extended toward the opening 34 of the bracket 26 ( Figure 1 , Figure 1A ), the mold section 76 is positioned on the smaller portion of the tapered end 82 of the tie rod 78, and the mold section is in its retracted position. The mold 74 also includes a circular spring 86 (see Figure 3 a), which surrounds the mold section 76 and biases it to the retracted position. When the tie rod 78 is pulled away from the opening 34 of the bracket 26 ( Figure 2 , Figure 2A), the die segments 76 axially fixed to the pinion 12 are urged radially outward by the interaction between the faceted surfaces 84 on each segment 76 and the conical faceted ends 82 of the tie rods 78. When the tie rods 78 return toward the opening 34 of the carriage 26, the die segments 76 travel radially inward under the influence of the circular springs 86 and return to the retracted position.

[0044] like Figure 1A and Figure 3A As further shown in FIG. 1 , each mold segment 76 has a mold face 88 that faces radially away from the pinion axis 16 so as to engage the inner surface of the tubular element received in the carrier 26. The mold face 88 has a contour shape that coordinates with the shape of the first cam surface 56 on the cam body 54. As described below, the first cam surface 56 and the mold face 88 cooperate to form a circumferential groove of a desired shape in the tubular element (see FIG. 1 ). Figure 2 , Figure 2A For tubular components having a nominal diameter of 1.25 inches or greater, it may be advantageous to use die 74 in conjunction with first cam surface 56 to more precisely control the final groove shape and size of the tubular component. Use of die 74 is expected to produce a better defined circumferential groove than is possible using the cam surface alone. Note that die face 88 has tapered surface 88a ( Figure 1A , Figure 2A and Figure 3A ), when the pipe element is larger than the nominal diameter, the tapered surface 88a provides free space for the second (controlled flare) cam surface 70 to form the end of the pipe element. When the controlled flare surface 70 is used to reduce the outer diameter of the pipe element, the surface 88a is also useful.

[0045] like Figure 1 and Figure 2As shown, the actuator that axially moves the tie rod 78 to expand and retract the mold 74 also includes a cylinder and piston 90. In this exemplary embodiment, the cylinder and piston 90 include a double-acting pneumatic cylinder 92 having a piston 94 coupled to the tie rod 78. The pneumatic cylinder 92 is mounted on a frame 96, which is attached to the intermediate shaft 14 and can move relative to the base 22. Therefore, the pneumatic cylinder 92 moves axially with the intermediate shaft 14, but its piston 94 can move the tie rod 78 relative to the intermediate shaft 14. A position sensor 98 is used to detect the position of the assembly including the tie rod 78, the mold 74, the pinion 12, the intermediate shaft 14, and the pneumatic cylinder 92 and its frame 96. The position sensor 98 can include, for example, a proximity sensor or a micro switch. A pressure sensor 100 is used to detect the pressure state of the pneumatic cylinder 92. Both the position sensor 98 and the pressure sensor 100 communicate with a controller 102, which can include, for example, a programmable logic controller or other microprocessor. Controller 102 uses information from position sensor 98 and pressure sensor 100 to control the operation of device 10 as described below.

[0046] like Figure 1 and Figure 7 As shown, the reduction gear train 104 is used to rotate the outer shaft 30 about the pinion axis 16. In this example embodiment, the reduction gear train 104 includes a worm 106 driven by a servomotor (not shown) controlled by the controller 102. The servomotor acts as an indexing drive and has an encoder that provides precise information about the position of the motor shaft, thereby allowing the rotation of the worm 106 to be precisely controlled.

[0047] The worm 106 meshes with the worm wheel 108. Figure 1 and Figure 7 As shown, the worm wheel 108 is mounted on an output shaft 110, which is supported on a bearing 112 between the output shaft 110 and a gear box 114 for rotation about the pinion axis 16, and the gear box 114 is fixed to the base 22. The output shaft 110 is coupled to the outer shaft 30 by a key 116, thereby ensuring the rotation of the outer shaft 30 when the output shaft 110 is rotated by the worm 106 and the worm wheel 108.

[0048] The operation of the device 10 begins as follows Figure 8 The cam bodies 54 are shown positioned with the discontinuities 60 and 70a in their respective first cam surfaces 56 and second cam surfaces 70 (not visible) facing the pinion axis 16, and the gaps 66 in their respective traction surfaces 64 (when present) also facing the pinion axis 16. This orientation of the cam bodies 54 is established when the gear 42 is assembled with the pinion 12 in the carrier 26 and is determined by the controller 102 ( Figure 1) and a servo motor (not shown) acting through the worm 106 and worm gear 108 is set to the starting position. The mold section 76 is in its retracted position ( Figure 1A ).

[0049] like Figure 1 and Figure 1A As shown, with the cam body 54 in the starting position and the die segment 76 retracted, the pipe element 118 to be slotted is inserted through the opening 34 in the bracket 26 and abuts the stop plate 36. The alignment of the gap 66 in the traction surface 64 (when present) with the corresponding discontinuities 60, 70a in the first cam surface 56 and the second cam surface 70 and the retracted position of the die segment 76 provides clearance for the pipe to be inserted. The pipe element 118 is further pressed against the stop plate 36, compressing the spring 38 and causing the assembly including the die 74, the pinion 12, the pull rod 78, the thrust bearing 40 and the pneumatic cylinder 92 to move axially relative to the base 22 and the fixed mount 20 attached to the base 22, thereby reaching a positive locking stop state when the thrust bearing 40 abuts the flange 28. The position of the assembly is sensed by the position sensor 98, which sends a signal indicating the position of the assembly to the controller 102. Upon receiving the position signal, the controller 102 commands the pneumatic cylinder 92 to pull the tie rod 78 away from the opening 34 of the bracket 26. This causes the mold segments 76 to move radially outward to the expanded position ( Figure 2 , Figure 2A ), thereby engaging the mold face 88 with the inner surface 120 of the tubular element 118. The expanded position of the mold segment 76 will vary depending on the inner diameter of the tubular element. The pneumatic cylinder 92 maintains a force on the pull rod 78, thereby locking the mold 76 against the inner surface of the tubular element. When the pressure sensor 100 senses a threshold lower pressure on the retract side of the pneumatic cylinder 92 indicating that the pull rod 78 has been pulled, it sends a signal to the controller 102 indicating that the mold segment 76 is in the expanded state. Upon receiving the mold state signal from the pressure sensor 100, the controller 102 commands the servo motor to rotate the worm 106, which rotates the worm gear 108. In this example, the rotation of the worm gear 108 causes the output shaft 110 to rotate counterclockwise (when in Figure 8 ) rotates, which causes its bond (key 116, see Figure 2A)'s outer shaft 30 rotates. Rotation of the outer shaft 30 causes the carrier 26 to rotate counterclockwise about the pinion axis 16. (The direction of rotation of the carrier 26 is predetermined by the arrangement of the first cam surface 56 on the cam body 54.) This causes the gears 42 and their associated cam bodies 54 to revolve about the pinion axis 16. However, because the intermediate shaft 14 is locked to the fixed mount 20 by interaction between the intermediate shaft portion 14a and the opening 24 of the fixed mount, the pinion 12 is fixed against rotation. Because the gear 42 engages (fixes) the pinion 12, the relative rotation of the carrier 26 about the pinion axis 16 causes the gears 42 and their associated cam bodies 54 to rotate about their respective gear axes 44 (see Figure 2 , Figure 2A and Figure 8 ). Rotation of the cam body 54 brings the traction surface 64 and the first cam surface 56 into contact with the outer surface 124 of the tubular element 118. As the increased radius region 58 and the constant radius region 62 of each first cam surface 56 traverse the tubular element 118, the traction surface 64 grips the tubular element while the first cam surface 56 embosses a groove into the tubular element outer surface 124. The die segment 76 engages and supports the inner surface 120 of the tubular element 118, and the die face 88 cooperates with the first cam surface 56 to form a circumferential groove.

[0050] The positions of the first cam surface 56 and the second (controlled flare) cam surface 70 on the cam body 54 are coordinated with the position of the tubular element 118 received in the bracket 26 so that the groove is formed at a desired distance from the end of the tubular element 118 and the flare at the end of the tubular element is controlled, i.e., limited or reduced to about its nominal diameter or less. The controller 102 rotates the bracket 26 through the necessary number of revolutions (depending on the gear ratio between the gear 42 and the pinion 12) to form a circumferential groove having a substantially constant depth for a tubular element having a uniform wall thickness. In this example embodiment, only one rotation of the bracket is required to form a complete circumferential groove of constant depth. When the groove formation is completed, the controller 102, through the action of the servo motor and gear train 104, returns the bracket 26 to a position where the gap 66 in the traction surface 64 and the discontinuity 60 in the first cam surface 56 and the discontinuity 70a in the second cam surface 70 are again facing the pinion axis 16 ( Figure 8 ). The controller 102 then commands the pneumatic cylinder 92 to move the tie rod 78 toward the opening 34 and allow the mold segments 76 to move radially inwardly to their retracted positions and disengage from the tube element 118 under the biasing force of the circular spring 86 ( Figure 1 and Figure 3A). This position of the cam body 54 and the die 74 allows the tubular element 118 to be withdrawn from the bracket 26. When the tubular element 118 is withdrawn, the spring 38 pushes the assembly including the pull rod 78, the pinion 12, the thrust bearing 40, the intermediate shaft 14, the pneumatic cylinder 92 and the die 74 back to its initial position, and the device 10 is again ready to groove another tubular element.

[0051] Significant advantages are achieved using the apparatus 10 because it applies minimal torque to the pipe element during the grooving process while forming the grooves to a fixed diameter. Figure 8 and Figure 5 As shown, this condition is achieved when: 1) the pitch diameter 126 of the pinion 12 is substantially equal to the outer diameter of the pipe element ( Figure 8 ); and 2) the pitch diameter 128 of the traction surface 64 is substantially equal to the pitch diameter 130 of the gear 42 ( Figure 5 ). When these two conditions are met, the traction surface 64 is constrained to traverse the outer surface of the tubular element with little or no tendency to cause the tube to rotate, and therefore only minimal torque is applied to the tubular element. The terms "equal" and "substantially equal" as used herein to refer to the relationship between the pitch diameters of the pinion, gear, and traction surface and the outer diameter of the tubular element mean that the pitch diameter of the pinion is close enough to the outer diameter of the tubular element, and the pitch diameter of the traction surface is close enough to the pitch diameter of the gear so that minimal torque is applied to the tubular element. For practical purposes, the pitch diameter of the pinion can be considered "equal" or "substantially equal" to the outer diameter of the tubular element if the difference between these values ​​is on the order of one hundredth of an inch. Because actual tubes have significant diameter tolerances relative to nominal values, it is expected that the relationship between the pitch diameter of the traction surface and the outer diameter of the tubular element may be affected by deviations in the tube diameter such that torque will be applied to the tubular element, making the use of an external fixture advantageous in these circumstances. In the apparatus 10, the die 74 can act as a fixture when it is mounted on the rotationally fixed pinion 12.

[0052] In an actual example design, an apparatus 10 suitable for grooving a tubular element having a nominal tube size of 2.5 inches uses four gears 42 and a cam body 54 as shown. The outer diameter of a 2.5 inch nominal tube is 2.875 inches. The pinion gear 12 having 36 teeth and a pitch diameter of 72 mm (2.835 inches) is close enough (with a difference of 0.040 inches) that the minimum torque is applied when the pitch diameter of the gear and the pitch diameter of the traction surface are also substantially equal to each other. This example embodiment uses a gear 42 having 36 teeth with a pitch diameter of 72 mm (2.835 inches). When embossed or otherwise prepared, the traction surface 64, while not a gear, has a substantially equivalent pitch diameter (i.e., the diameter of a cylinder that provides the same motion as an actual gear) that is impressed into the tube as it is passed by the traction surface. A difference of the order of one hundredth of an inch between the pitch diameter of the traction surface and the pitch diameter of the gear meets this definition of "equal" or "identical" in practical applications. Considering that the gear ratios between the pinion 12 and the gear 42 are equal in this example, it is obvious that the carrier 26 will rotate one revolution to form a complete circumferential groove around the tubular element.

[0053] In another example design suitable for a 4 inch nominal size tube having an outer diameter of 4.5 inches, a pinion with 72 teeth and a pitch diameter of 4.5 inches is feasible. This design uses 4 gears, each with 72 teeth and a pitch diameter of 4.5 inches. A 1:1 ratio between the pinion and the gear indicates that a single rotation of the carrier is required to form a complete groove. Other ratios between the pinion and the gear will result in multiple or partial rotations of the carrier to form a complete groove.

[0054] The device 10 is designed so that the carrier 26 and its associated gear 42, cam body 54, pinion 12, outer shaft 30, intermediate shaft 14 and die 74 together with other related components constitute an assembly 132 that is interchangeable with the gear train 104 to allow the device to be easily adapted to groove a range of tubes having different diameters and wall thicknesses. Interchangeability is provided by using a removable clip 134 to secure the outer shaft 30 to the gear box 114 and a key 116 between the outer shaft 30 and the output shaft 110 of the worm gear 108, and by attaching the intermediate shaft to the frame 96 of the pneumatic cylinder 92 by engaging the frame with a slot 136 in the intermediate shaft 14 and also attaching the piston 94 to the pull rod 78 using interengaging slots and shoulders 138. The assembly 132 can be removed by lifting the pneumatic cylinder 92, disengaging the frame 96 from the intermediate shaft 14 and the piston 94 from the pull rod 78, and then removing the retaining clip 34 (thereby allowing the outer shaft 30 to be disengaged from the worm gear 108) and sliding the assembly along the pinion axis 16. A different bracket assembly suitable for grooving a different pipe element can then be substituted.

[0055] Apparatus 10 according to the present invention are expected to improve the efficiency of pipe grooving operations because they will operate quickly and accurately over a wide range of pipe element sizes and schedules without the need for brackets to support the pipe elements and accommodate their rotation and ensure alignment. Apparatus 10 will also allow grooving of curved pipe elements and pipe assemblies having elbow joints without involving rotational movement of lateral pipe elements.

[0056] Fig. 9 Another device 11 for forming a circumferential groove in a tubular element is shown. The device 11 comprises a pinion 13 which is fixedly mounted against rotation about a pinion axis 15 arranged coaxially with the pinion. The rotational fixation of the pinion 13 is achieved by mounting it on one end 17 of a pinion shaft 19, the opposite end 21 of which is fixed to a post 23 by a key 25. The post is mounted on a base 27.

[0057] The bracket 29 surrounds the pinion 13. The bracket 29 is mounted on a flange 31 of a drive shaft 33. The drive shaft 33 is hollow, surrounds the pinion shaft 19 and is coaxial with the pinion shaft 19. A bearing 35 positioned between the drive shaft 33 and the pinion shaft 19 allows the drive shaft and therefore the bracket 29 attached to the drive shaft to rotate about the pinion axis 15. The bracket 29 defines an opening 37 for receiving a tube element in which a groove will be formed. The opening 37 is arranged coaxially with the pinion axis 15. As shown in FIG. Fig. 9 and Fig.11 As shown, a cup 39 is mounted coaxially with the pinion 13. A tube element abuts the cup 39 and is mounted in this example on a cup shaft 41 which extends coaxially through a hole 43 in the hollow pinion shaft 19. The cup shaft 41 is movable axially along the pinion axis 15 and is biased toward the opening 37 by a spring 45 acting between the pinion shaft 19 and the cup 39. The end 47 of the cup shaft 41 opposite the cup 39 is used in conjunction with a switch 49 mounted near the post 23 to activate the device, as described below. In this example embodiment, the switch comprises a proximity sensor, but could also be a contact switch such as a micro switch.

[0058] A plurality of gears 51 are mounted on the bracket 29. Fig. 9 and Fig.11 In the exemplary embodiment shown, the carrier has three gears 51 spaced 120° apart from each other. Each gear 51 is rotatable about a respective gear axis 53. In a practical embodiment, each gear is mounted on a gear shaft 55, which is fixed between a front plate 57 and a rear plate 59 constituting the carrier 29. Bearings 61 positioned between each gear 51 and its respective shaft 55 provide low-friction rotation of the gear within the carrier 29. Each gear 51 engages with a pinion 13.

[0059] like Fig.12As shown, a corresponding cam body 63 is mounted on each gear 51. A corresponding cam surface 65 extends around each cam body 63. The cam surface 65 can engage with a tube element received through the opening 37 and abutting the cup 39. Fig.13 As shown, each cam surface 65 includes an area 67 of increased radius of the cam surface and a discontinuity 69. The discontinuity 69 is a location where the cam surface 65 does not contact the cam body 63 of the tubular element. It is further advantageous to include as part of each cam surface 65 an area 71 of constant radius located adjacent the discontinuity 69. The traction surface 73 (see Fig.12 ) extends around at least one of the cam bodies 63. Fig.11 In the example shown, a corresponding traction surface 73 extends around each cam body 63. The traction surfaces 73 may also engage with a tubular element received within the bracket 29, but each traction surface has a gap 75 that is axially aligned (i.e., in a direction along the gear axis 53) with the discontinuity 69 in the cam surface 65 on each cam body 63. Fig.12 As shown, the traction surface 73 may include a plurality of protrusions 77 extending outwardly therefrom. The protrusions provide additional grip between the tubular element and the traction surface 73 during operation of the device, and may be formed, for example, by embossing the traction surface. The traction surface has a pitch diameter 87. When the protrusions 68 are present on the traction surface 64, the pitch diameter 87 of the traction surface will be determined by the interaction of the protrusions 87 with the tubular element 79 (including the embossing performed by the protrusions 87 on the tubular element 79). If the protrusions 68 are not present, the pitch diameter 87 of the traction surface 64 will be equal to the pitch diameter of the traction surface. Fig.12 As further shown, cam surface 65 is positioned between gear 51 and traction surface 73 in spaced relation to the traction surface but closer to the traction surface than the gear.

[0060] like Fig. 9 and Figure 7 As shown, the reduction gear train 104 is used to rotate the drive shaft 33 about the pinion axis 15. In this exemplary embodiment, the reduction gear train 104 includes a worm 106 driven by a servo motor (not shown) controlled by a microprocessor such as a programmable logic controller (not shown). The servo motor acts as an indexing drive and has an encoder that provides precise information about the position of the motor shaft, thereby allowing precise control of the rotation of the worm 106.

[0061] The worm 106 meshes with a worm wheel 108. The worm wheel 108 is mounted on a hollow output shaft 110, which is supported on a bearing 112 between the output shaft 110 and a gear box 114 to rotate about the pinion axis 15. The output shaft 110 is coupled to the drive shaft 33 by a key 95, thereby ensuring the rotation of the drive shaft 33 when the output shaft 110 is rotated by the worm 106 and the worm wheel 108.

[0062] The operation of the device 11 begins as follows Fig.14 The cam bodies 63 are shown positioned with the discontinuities 69 in their respective cam surfaces 65 facing the pinion axis 15 and with the gaps 75 in their respective traction surfaces 73 (see FIG. Fig.11 ) also faces the pinion axis 15. This orientation of the cam body 63 is established when the gear 51 is assembled with the pinion 13 in the bracket 29 and is set to a starting position by the control system and a servomotor (not shown) acting through the worm 106 and the worm wheel 108.

[0063] When the cam body 63 is in Fig.14 In the starting position shown, the slotted pipe element 79 is inserted through the opening 37 in the bracket 29 and abuts the cup 39 (see Fig. 9 ). The alignment of the gap 75 in the traction surface 73 with the discontinuity 69 in the cam surface 63 (see Fig.11 ) provides clearance for tube insertion. The tube element is further pressed against the cup 39, compressing the spring 45 and moving the cup 39 against the positive locking stop (in this example, the face of the pinion shaft 19), so that the end 47 of the cup shaft 41 interacts with the switch 49 (in this example, a proximity switch). Closing the switch 49 sends a signal to the control system, which commands the servomotor to rotate the worm 106, which rotates the worm gear 108. In this example, the rotation of the worm gear 108 causes the output shaft 110 to rotate counterclockwise (when in Fig.1495). The rotation of the drive shaft 33 causes the carrier 29 to rotate counterclockwise about the pinion axis 15. (The direction of rotation of the carrier 29 is determined by the arrangement of the cam surfaces 65 on the cam bodies 63.) This causes the gears 51 and their associated cam bodies 63 to revolve about the pinion axis 15. However, because the pinion shaft 19 is keyed to the post 23 by the key 25, the pinion 13 is fixed against rotation. Because the gear 51 engages the pinion 13, the relative rotation of the carrier 29 about the pinion axis 15 causes the gears 51 and their associated cam bodies 63 to rotate about their respective gear axes 53. The rotation of the cam bodies 63 brings the traction surfaces 73 and cam surfaces 65 into contact with the outer surface 83 of the tube element 79. As the increased radius region 67 and constant radius region 71 of each cam surface 65 traverse the tube element, the traction surfaces 73 grip the tube element 79, while the cam surfaces 65 emboss grooves into its outer surface 83. When the tubular element is inserted far enough to reach the positive locking stop and trigger the switch 49, the position of the cam surface 65 on the cam body 63 is coordinated with the position of the tubular element so that a groove is formed at the desired distance from the end of the tubular element. The controller rotates the bracket 29 through the necessary number of revolutions (depending on the transmission ratio between the gear 51 and the pinion 13) to form a circumferential groove of substantially constant depth in the tubular element. When the groove formation is completed, the controller returns the bracket 29 to a position in which the gap 75 in the traction surface 73 and the discontinuity 69 in the cam surface 65 are again facing the pinion axis 15 (see Fig.14 ). This position of the cam body 63 allows the tubular element 79 to be withdrawn from the bracket 29 and the device 11 is ready to groove another tubular element.

[0064] Significant advantages are achieved using the apparatus 11 because it applies minimal torque to the pipe element during the grooving process while forming the groove to a fixed diameter. This condition is achieved when: 1) the pitch diameter of the pinion 13 is 85 ( Fig.11 ) is equal to the outer diameter of the tube element 79; and 2) the pitch diameter 87 of the traction surface 73 is equal to the pitch diameter 89 of the gear 51 ( Fig.12). When these two conditions are met, the traction surface 73 is constrained to traverse the outer surface of the tubular element with little or no tendency to cause the tube to rotate, and therefore only minimal torque is applied to the tubular element. The term "equal" as used herein to refer to the relationship between the pitch diameter of the pinion and the outer diameter of the tube means that the pitch diameter is close enough to the outer diameter so that minimal torque is applied to the tubular element. A difference between the pitch diameter and the outer diameter of the tubular element of the order of one hundredth of an inch satisfies this qualification of "equal" in practical applications. Because actual tubular elements have significant diameter tolerances relative to nominal values, it is expected that the relationship between the pitch diameter of the traction surface and the outer diameter of the tubular element may be affected by deviations in the tube diameter such that torque will be applied to the tubular element, and it is advantageous to use an external clamp 99 in these cases (see Fig. 9 ).

[0065] In a practical example design, an apparatus 11 adapted for grooving a 1 inch nominal diameter pipe uses three gears 51 and a cam body 63 as shown. The outer diameter of a 1 inch nominal pipe is 1.315 inches. The pinion 13 having 21 teeth and a pitch diameter of 1 5 / 16 inches (1.3125 inches) is close enough (with a difference of 0.0025 inches) that minimal torque is applied when the pitch diameters of the gear and traction surface are also equal to each other. This example embodiment uses a 42-tooth gear 51 with a pitch diameter of 2 5 / 8 inches. When embossed or otherwise prepared, the traction surface 73, while not a gear, has an equivalent pitch diameter (i.e., the diameter of a cylinder that provides the same motion as an actual gear) that is impressed into the pipe as it is passed by the traction surface. A difference of the order of one hundredth of an inch between the pitch diameter of the traction surface and the pitch diameter of the gear satisfies this definition of "equal" or "equivalent" in practical applications. Considering the transmission ratio between the pinion 13 and the gear 51 in this example, it is clear that the carrier 29 will make two revolutions to form a complete circumferential groove around the tubular element.

[0066] In another example design suitable for a 2 inch nominal tube having an outer diameter of 2 3 / 8 inches (2.375 inches), a pinion with 30 teeth with a pitch diameter of 2.362 inches is feasible (with a difference of 0.013 inches). This design uses 5 gears, each with 30 teeth and a pitch diameter of 2.362 inches. The 1:1 ratio between the pinions and gears indicates that a single rotation of the carrier is required to form a complete groove. Designs with more than three gears are advantageous when thin-walled or larger diameter tubular elements are being grooved because such tubes have a tendency to elastically bulge over the areas between the cams when compressed between three cam surfaces spaced 120° apart from each other. This elastic behavior causes a greater rebound of the tubular element toward its nominal shape and inhibits groove formation. However, more gears means more cams exerting force at more points around the tubular element to better support the tubular element, and a half turn thus significantly reduces elastic bulging. More constraints at closer spacing around the pipe element force the deformation largely into the plastic zone where springback is reduced and compensated.

[0067] Another example design uses 4 gears and cams for tube elements having nominal diameters of 1.25 and 1.5 inches. Gear to pinion ratios of 1.5:1 and 1:1 are also possible with this design.

[0068] The device 11 is designed so that the bracket 29 and its associated gear 51, cam body 63, pinion 13, cup shaft 41, cup 39, spring 45, drive shaft 33 and pinion shaft 19 constitute an assembly 91 that is interchangeable with the gear train 104 to allow the device to be easily adapted to groove a range of tubes having different diameters and wall thicknesses. Interchangeability is imparted by the use of a key 25 between the pinion shaft 19 and the post 23 and a key 95 between the drive shaft 33 and the output shaft 110, coupled with a retaining nut 97 threadedly connected to the drive shaft 33 and acting against the output shaft 110. When the retaining nut 97 is disengaged from the threaded engagement with the drive shaft 33, the assembly 91 can be removed by sliding it along the pinion axis 15. A different bracket assembly suitable for grooving different tubular elements can then be substituted.

[0069] Apparatus 11 according to the present invention are expected to improve the efficiency of pipe grooving operations because they will operate quickly, accurately and safely over a wide range of pipe element sizes and schedules without the need for brackets to support the pipe elements and accommodate their rotation and ensure alignment. Apparatus 11 will also allow pipe assemblies having elbow joints to be grooved without involving rotational movement of the lateral pipe elements.

[0070] Figures 15 to 20 Another exemplary embodiment of a slotting device 140 according to the present invention is shown. Similar to the above-described device 11, the device 140 includes a plurality of gears 51, Fig.15 The embodiment 140 shown has five gears. Fig.12 and Fig.13 As shown, each gear 51 includes a cam body 63 that supports a cam surface 65 and an optional traction surface 73. Various features of the gears, cam surfaces, and traction surfaces are described above. Fig.15 As shown, gear 51 is rotatably mounted on carrier 29, which itself rotates about pinion axis 15, similar to device 11. As described above, carrier 29 includes front plate 57 and rear plate 59, with front plate 57 defining opening 37 for receiving a pipe element to be grooved. Fig.16 As shown, at least one of the gears 51 meshes (directly engages) with the pinion 13, which is coaxially mounted on the pinion shaft 19. (In the example embodiment shown, all gears directly engage the pinion 13.) Both the pinion 13 and the pinion shaft 19 are coaxially arranged relative to the pinion axis 15 (see Fig.16 ), and both are rotationally fixed relative to the bracket 29. For the operation of the slotting device 140, the bracket 29 can be installed instead of the device 11. Fig. 9 On drive shaft 33 shown, and as described above for device 11, when the carrier rotates about pinion axis 15, gears 51 rotate about their respective gear axes 53, with cam surfaces 65 forming circumferential grooves in the tube element.

[0071] like Fig.16 As shown, device 140 differs from device 11 in that it has a flared cup 142 positioned adjacent pinion 13 and surrounding a tube end stop 144. Tube end stop 144 includes a plate 146 defining a tube engaging surface 148. Plate 146 is mounted on and extends outwardly from sleeve 150, which is fixedly mounted on a cup shaft 152. Cup shaft 152 is received within a bore 154 of pinion shaft 19 coaxially aligned with pinion axis 15. A first end 159 of cup shaft 152 extends from bore 154, and both cup 142 and tube end stop 144 are mounted proximate the extended first end 159 of cup shaft 152. The cup shaft 152 is movable relative to the pinion shaft 19 in a direction along the pinion axis 15 and is biased toward the cam surface 65 of the cam body 63 by a retaining spring 156, which in this example is a coil spring coaxially arranged about the pinion axis 15 and acting between the pinion shaft 19 and a shoulder 158 of the sleeve 150. The cup shaft 152 is retained within the pinion shaft bore 154 against the biasing force of the spring 156 by engagement between the enlarged second end 160 of the cup shaft and an undercut 162 in the pinion shaft bore 154. In this example, a threaded nut 164 engages the first end 159 of the cup shaft 152 to retain the tube end stop 144 to the cup shaft.

[0072] The cup 142 includes a side wall 166 disposed coaxially with the pinion axis 15. The side wall 166 defines an interior 167 and surrounds the plate 146 of the tube end stop 144. A radially extending rear wall 168 connects the side wall 166 to an axially extending hub 170. The hub 170 receives the cup shaft 152 by engaging the sleeve 150 of the tube end stop 144 and is movable relative to the cup shaft 152 along the pinion axis 15. A cup spring 172 can act between the cup 142 and the pinion 13 to bias the cup 142 away from the pinion 13. In this example, the spring 172 is a conical spring that is compressed flatter than would be possible using a straight compression coil spring to allow a greater range of axial movement to the cup 142. Thus, the cup 142 "floats" (moves independently) relative to the tube end stop 144. The side wall 166 defines an inner surface 174 that engages a tube element as described below. The inner surface 174 has a first diameter 174a located away from the pinion 13 and a second diameter 174b located near the pinion. The first diameter 174a is greater than the second diameter 174b, resulting in a flared cup 142. The tube end stop 144 is positioned within the interior 167 between the first diameter 174a and the second diameter 174b. In an exemplary embodiment, the inner surface 174 is advantageously tapered. In a practical design, the inner surface 174 defines an included angle 176, which can range between about 11° (for a 1.25 inch diameter tube) to about 12° (for a 1.5 inch diameter tube) and up to about 16° (for a 2 inch diameter tube). The taper of the tapered surface 174 is designed so that the cup 142 engages the tube element before the tube end stop 144, as described below.

[0073] Reference Figures 17 to 19 The operation of the flare cup 142 and the tube end stop 144 is described. Fig.17 As shown, with the cam surface 65 and the traction surface 73 oriented with their respective discontinuities 69 and gaps 75 facing the pinion axis 15, the tubular element 178 is inserted into the bracket 29 and received within the cup 142. As the tubular element is inserted, the outer circumference of the end of the tubular element 178 first engages the inner surface 174 (note the gap 180 between the tubular element and the tube engaging surface 148 of the tube end stop 144). The taper of the inner surface 174 is designed to accommodate dimensional tolerances on the tubular element diameter so that the gap 180 initially exists regardless of the actual diameter of the particular tubular element. Fig.17 In the example shown, the tube element 178 is at the smaller end of the diameter tolerance range, and the tube element engages relatively deeply into the cup interior 167. Fig.18As shown, the tube element 178 is further inserted into the bracket 29. In response, the cup 142 moves axially along the sleeve 150 relative to the tube end stop 144 and the cup shaft 152, compressing the cup spring 172 between the pinion 13 and the cup 142. The axial movement of the cup 142 continues independently of the tube end stop 144 until the gap 180 is closed and the end of the tube element 178 engages the tube engaging surface 148 of the plate 146. Fig.19 As shown, continued insertion of the tube element 178 causes the tube end stop 144 to move relative to the pinion 13, thereby compressing both the spring 172 and the coil spring 156. Axial movement of the tube element 178, the cup 142, and the tube end stop 144 is stopped when the sleeve 150 of the tube end stop engages the internal shoulder 181 within the bore 154 of the pinion shaft 19 (compare Fig.18 and Fig.19 ). Sleeve 150 and inner shoulder 181 are sized to achieve two effects: 1) position tubular element 178 relative to cam surface 65 so that the circumferential groove formed in the tubular element will be at a desired distance from the end of the tubular element when bracket 29 is rotated; and 2) position enlarged end 160 of cup shaft 152 to trigger a switch of activation device 140 to rotate bracket 29 when tubular element 178 is in the correct position to form the circumferential groove. Similar to device 11, the switch can be a proximity sensor 49, such as Fig.10 As shown. Fig.16 As shown, a threaded screw 182 may be positioned in the enlarged end 160 of the cup shaft 152 to provide adjustability of the apparent length of the cup shaft 152 for fine tuning the switch throw. Fig.16 and Fig. 20 As shown, in some cases, increased accuracy of the location of the circumferential groove on the pipe element 178 can be provided by using a reverse tapered surface 184 in the pipe engaging surface 148 of the plate 146. This feature is advantageous when the pipe element cut by a roller cutter is being grooved. The roller cutter does not work by removing material (kerf cutting), but rather by separating the material at the cutting plane using a wedge-shaped blade. Therefore, the cut end of the pipe element will have a tapered outer surface. The reverse tapered surface 184 is designed to accommodate this tapered outer surface and ensure that the circumferential groove is positioned at the desired distance from the end of the pipe element 178 measured from the point where the pipe element is at its full outer diameter, rather than at the end of the tapered surface. Reverse taper angles of up to about 5° can be used in practical designs of the reverse tapered surface 184.

[0074] Use of a floating cup 142 according to the present invention provides the following advantages: 1) the cup accommodates dimensional tolerances of the outer diameter of the tubular element; 2) the cup limits radial expansion of the end of the tubular element during grooving, and thus reduces flaring (permanent radial deformation); and 3) the cup limits localized outward bulging of the tubular element in the area between the cam surfaces 65 of the plurality of cam bodies 63, and thus helps prevent the end of the tubular element from being "out of round." It is expected that the example apparatus 140 according to the present invention will be able to groove tubular elements more quickly and more accurately than grooving apparatus according to the prior art.

Claims

1. A device for forming a circumferential groove in a pipe element, the device comprising: a pinion gear secured against rotation about a pinion gear axis disposed coaxially with said pinion gear; a carrier surrounding the pinion, the carrier being rotatable about the pinion axis and defining an opening disposed coaxially with the pinion axis for receiving the tube element; a cup positioned adjacent the pinion, the cup having a side wall disposed coaxially with the pinion axis and defining an interior, the side wall having an interior surface, the interior surface having a first diameter located distally from the pinion and a second diameter located proximate to the pinion, the first diameter being greater than the second diameter, the interior facing the opening for receiving the tube element, the cup being movable along the pinion axis toward and away from the pinion; a tube end stop positioned within the interior between the first and second diameters, the tube end stop being movable relative to the cup along the pinion axis toward and away from the pinion; a retaining spring acting on the tube end stop and biasing the tube end stop away from the pinion; a plurality of gears mounted on the carrier, each of the gears being rotatable relative to the carrier about a respective gear axis, at least one of the gears being directly engaged with the pinion; a plurality of cam bodies, each of the cam bodies being mounted on a corresponding one of the gears; A plurality of first cam surfaces, each of the first cam surfaces extending around a respective one of the cam bodies and engageable with the tubular element received within the opening, each of the first cam surfaces including a region of increased radius, each of the first cam surfaces including a first discontinuity in the first cam surface.

2. The device according to claim 1, wherein: Each of the gears is directly engaged with the pinion.

3. The device of claim 1 further comprising a cup spring acting between the cup and the pinion and biasing the cup away from the pinion.

4. The device according to claim 1, wherein: The side wall has a tapered inner surface.

5. The device according to claim 4, wherein: The tapered inner surface defines an included angle from 11° to 16°.

6. The device of claim 1, further comprising a pinion shaft, the pinion being fixedly mounted on the pinion shaft, and the carrier being rotatably mounted on the pinion shaft.

7. The device according to claim 6, wherein: The pinion shaft defines a bore coaxially aligned with the pinion axis.

8. The apparatus of claim 7 further comprising a cup shaft positioned within the bore, the cup shaft being movable within the bore along the pinion axis, the first end of the cup shaft extending from the bore, the cup being mounted proximate the first end of the cup shaft.

9. The device according to claim 8, wherein: The cup comprises: a hub coaxially receiving the cup axle; A rear wall extends outwardly from the hub, the side walls being attached to the rear wall.

10. The device according to claim 8, wherein: The tube end stop comprises: a sleeve fixedly mounted on the cup shaft; A plate is mounted on the sleeve and extends outwardly from the sleeve, the plate defining a tube engaging surface facing the opening.

11. The device according to claim 10, wherein: The plate also includes a reverse tapered surface positioned within the tube engaging surface.

12. The device according to claim 10, wherein: The cup comprises: a hub coaxially receiving the sleeve; A rear wall extends outwardly from the hub, the side walls being attached to the rear wall.

13. The apparatus according to claim 6, further comprising: base; A column is mounted on the base, and the pinion shaft is fixedly mounted on the column.

14. The device according to claim 3, wherein: The cup spring includes a conical spring.

15. The device according to claim 2, wherein: Each of the gears has the same pitch diameter.

16. The device according to claim 1, wherein Each of the first cam surfaces includes a region having a constant radius positioned adjacent a respective one of the first discontinuities.

17. The device of claim 1 further comprising at least one traction surface extending around one of the cam bodies, the at least one traction surface having a gap therein axially aligned with the first discontinuity of the first cam surface around the one cam body.

18. The device according to claim 17, wherein: The at least one traction surface includes a plurality of protrusions extending outwardly therefrom.

19. The device according to claim 17, wherein: The at least one traction surface is positioned proximate to the first cam surface surrounding the one cam body.

20. The device according to claim 17, wherein: The pitch diameter of the pinion gear is equal to the outer diameter of the tube element.

21. The device according to claim 20, wherein: The at least one traction surface has a pitch diameter equal to the pitch diameter of one of the gears.

22. The device of claim 20 further comprising a plurality of said traction surfaces, each of said traction surfaces extending around a respective one of said cam bodies, each of said traction surfaces having a gap therein, each of said gaps being axially aligned with a respective one of said discontinuities of said first cam surface on each of said cam bodies, each of said traction surfaces having a pitch diameter equal to said pitch diameter of said gear.

23. The device of claim 1, comprising at least three of said gears.

24. The device of claim 1, comprising at least five of said gears.

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