ASSEMBLY FOR USE IN A BELTTONG

Abstract: An assembly for use in a tong (2) having a housing (3) and a rotary element (16) rotatably mounted in said housing (3), comprises: (a) a belt anchor assembly (21), (b) a belt carrier assembly (31) which can be mounted on said rotary element (16), (c) a belt (32) extending between the belt anchor assembly (21) and the belt carrier assembly (31), and (d) at least one jaw (30) for facilitating gripping a pipe (8).

Description: Assembly for use in a belttong This invention relates to an assembly for use in a tong, a belt holder and a belt anchor assembly provided with such a belt holder. Gripping elements or jaws used in conventional tongs are designed to operate with very high load variations between leading and trailing dies. Jaw guiding slides or linkages are used to control die contact and force delivery. Jaw guides absorb energy and detract from torque delivery. Uneven die loading causes marring or damage to the tubular surface. In some designs die loading becomes increasingly asymmetrical as pipe size is reduced, substantially increasing die wear and the probability of damage. A power tong should preferably be able to cover a range of pipe sizes without difficulty, and if a further pipe size change is needed, it should be effected with only an interchange of parts. Maintenance and life problems can have an economic significance far in excess of the cost of the dies or even the pipe involved, because the down time that results when replacements or repair must be made involves not only material costs, but also drilling rig and crew costs and the continuing charges for other specialized tools and equipment present at the drilling rig. Thus a power tong system which required frequent replacement of dies or other elements or which causes undue damage to sections in a pipe string would be far less desirable than a power tong system which operates steadily and uniformly. Both jaw/die tongs and belt/chain tongs can be used with relatively hard and rigid metal tubulars such as casing and tubing. When these tongs are used with thin tubulars or tubulars made from relatively "softer" metals or from premium metals such as high alloy steels or low carbon steels or tubulars made from non-metal materials such as fibreglass, they often severely damage the tubular. When working with fibreglass reinforced pipe, serrated or toothed dies (or jaws with such dies) can easily cause marking or damage to tubulars. Such damage results in destruction of reinforcing filaments in the tubular and can considerably reduce the tubular's strength. When the outside surfaces of the fibreglass pipe are irregular or outside diameters of individual joints vary, either inadequate or extreme die penetration is achieved. Our US Patent 4,774,860, which forms the basis of the precharacterizing portion of Claim 1, addresses these problems and teaches a new tong which can and has been successfully used with softer tubulars such as fibreglass pipe. One aspect of the present invention, at least in its preferred embodiments, improves this tong. According to this aspect of the present invention there is provided an assembly for use in a tong having a housing and a rotary element rotably mounted in said housing, said assembly comprising: a) a belt anchor assembly which comprises a body; b) a belt carrier assembly which can be mounted on said rotary element; and c) a belt extending between said belt anchor assembly and said belt carrier assembly; characterized in that: said assembly further comprises at least one jaw for facilitating gripping a pipe. Preferably, said jaw is mounted on said belt anchor assembly. Advantageously, said body of said belt anchor assembly is provided with a cam surface and said belt carrier .assembly is provided with a cam follower, the arrangement being such that, in use, rotation of said rotary element carries said belt around a pipe in said 5 tong until said cam follower engages and moves along said cam surface, whereafter said belt anchor assembly, said belt carrier assembly, said belt and said rotary element rotate with said pipe. Preferably, the cam surface on the belt anchor 0 assembly includes a cam nesting surface for receiving said cam follower. Advantageously, the cam nesting surface prevents said cam follower from proceeding past said cam nesting surface. 5 Preferably, the belt anchor assembly includes a belt holder which comprises: a) a belt anchor shaft having a top flange and a bottom flange, said top flange and said bottom flange each having a keyway therein, said ke ways being 0 substantially aligned so that, in use, a key can pass through both said keyways and a loop at one end of said belt. Advantageously, the belt anchor shaft is rotatable with respect to said belt anchor assembly so 5 that, after positioning of said key in said keyways, said belt anchor shaft can be rotated to tighten the belt and secure the key in place. The present invention also provides a tong provided with an assembly in accordance with the 0 invention. Preferably, said tong comprises drive means for rotating the rotary element. Advantageously, said belt anchor assembly is secured to at least one brake plate which is inhibited 5 against movement by a brake. The belt may be made, for example, from metal, plastic, ^ nylon, woven material, delrin, or aramid fibre materials such as KEVLAR (Registered Trademark) material. The present invention also provides a belt a belt holder for use in a tong having a belt anchor assembly characterized in that said belt holder comprises a belt anchor shaft having a top flange and a bottom flange, and a keyway in each of said top flanges and said bottom flange, said keyways being substantially aligned so that, in use, a key can pass through both said keyways and a loop at one end of said belt. There is also provided a belt anchor assembly provided with a belt holder in accordance with the invention. Preferably, the belt anchor assembly shaft is rotatably mounted in said belt anchor assembly. For a better understanding of the invention, reference will now be made, by way of example, to the accompanying drawings, in which:- Fig. 1 is a top plan view, partially cut away, of a tong according to the present invention with its top mount plate removed and its housing and drive gears shown in outline; Fig. 2 is a side view of the tong of Fig. 1 partially in cross-section; Figs. 3-6 are top plan views showing operative portions of the tong of Fig. 1 during various stages of rotation about a tubular; Fig. 7 is a top plan view of a belt holding apparatus (also shown in Figs. 1 and 2) according to the present invention; and Fig. 8 is a side view, in cross-section, of the mounting of the jaw in the tong of Fig. 1. Referring to Fig. 1, a tong 2 has a housing 3 (shown in outline) and a drive train including idler gears 4, an intermediate gear 5, and a drive gear 6. An opening 7 in the housing 3 is provided for receiving a pipe 8 to be rotated. The pipe 8 is shown centered in . the tong 2. The idler gears 4 mesh with and turn a rotary element 16. Conventional drive means, not shown, drive gear 6. A gate 13 is pivotably mounted across the opening 7 to close it off during use. A belt anchor assembly 21, a belt 32 and a belt carrier assembly 31 are disposed within the tong 2. As better shown in Fig. 2, the belt anchor assembly 21 is bolted to bottom and top brake plates 18, 20 which in turn are acted upon by braking apparatus such as conventional band brakes 77, 79. It is this braking force which the rotary element 16 must overcome to move the belt anchor assembly 21. Once this force is overcome the rotary element 16, belt 32, belt carrier assembly 31, and belt anchor assembly 21 will move in unison and cause the pipe 8 to rotate. The rotary element 16 comprises a top rotary guide 55, a rotary element 17, and a bottom rotary guide 57, which are bolted together in a conventional manner. The bottom and top brake plates 18, 20 move relative to the top and bottom rotary guides 55, 57 and carry with them the belt anchor assembly 21. A top anchor assembly plate 22 is bolted to the top brake plate 20. A bottom anchor assembly plate 24 is bolted to the bottom brake plate 18. A jaw 30 with a portion 29 for the belt 32 is bolted with bolts 90 to spacer bolt 58 which pass through holes 66 in the top and bottom anchor assembly plates 22 and 24. A recess 84 (Fig. 3) receives a rear housing 35 of a jaw 30. A piece, pieces, or a coating of rubber, plastic, granular or other high friction material 64 may be applied to the interior of jaw 30 for better holding of the pipe 8. The belt carrier assembly 31 has top 34 and bottom 36 pivot arms which are movably connected to the rotary element 16 with the pivot pin 38 through a hole 74 and are spaced apart so that the belt 32 can pass between them. Cam rollers 40 are rotatably mounted at the ends of a pin 42 which is mounted through the top and bottom pivot arms 34, 36. A belt shaft assembly 44 is mounted through the top and bottom anchor assembly plates 22, 24 and includes a belt anchor shaft 46 having upper 50 and lower 48 flanges between which the belt 32 can pass and which serve to correctly position the belt 32. Each flange 50, 48 has a keyway therein 54, 52 respectively for receiving a key 56 for holding a loop of the belt 32. An idler shaft 62 makes it possible for more of the belt to contact the pipe 8. The belt shaft assembly 44 serves to hold and tighten the belt 32. As shown in Fig. 7, retention of a loop of the belt 32 in the anchor assembly is accomplished by the keyways 54, 52 into which the key 56 is inserted. The belt shaft assembly 44 sits in an opening 53 in the belt anchor assembly 21. Quick removal and replacement of the belt 32 is facilitated by rotating the rotary element 16 so that the opening 82 in the rotary element 16 reveals the key 56 and the belt 32. The belt 32 is then unwound off the belt anchor shaft 46, and the belt anchor shaft 46 is rotated so that the keyways 52, 54 face the opening 82. The belt end and key 56 are then removed. A new belt 32 is added by placing the key 56 in a loop in the end of the belt 32, then sliding the key 56 (with belt attached) into the keyways 52, 54 and rotating the belt anchor shaft 46 so that the key 56 is retained circumferentially by the keyways 52, 54 and radially by the opening 53. The opposite end of the belt 32 is disengaged from the belt carrier assembly 31 by removing pivot pin 38 which allows removal of the belt carrier assembly 31 and thereby easy removal and replacement of the belt 32. Various stages in the operation of the tong 2 will now be described. As shown in Fig. 3, the belt 32 is relatively loose and limp. Fig. 4 illustrates the location of the belt after a slight clockwise rotation of the rotary element 16. The belt anchor assembly 21 remains stationary under the control of the band brakes 77, 79. However, belt carrier assembly 31 has rotated clockwise. The belt 32 is not yet in contact with the exterior surface of the pipe 8. Referring now to Fig. 5, the rotary element 16 has moved further in a clockwise direction but the belt 32 has not yet contacted the pipe 8. The cam rollers 40 have contacted and started to follow cam surfaces 26 of the top and bottom anchor assembly plates 22, 24. As shown in Fig. 6, upon further clockwise rotation of the rotary element 16, the cam rollers 40 have been received in, stopped in, and are being held by cam nesting surfaces 78. The belt 32 is tightly wrapped around the pipe 8 and the top and bottom pivot arms 34, 36 have pivoted as the belt 32 has tightened. The rotary element 16 cannot move further unless it moves the belt carrier assembly 31 and the belt anchor assembly 21 with it, thereby rotating the pipe 8 around which the belt 32 is wrapped. As shown in Figs. 3 to 6 the belt carrier assembly 31 is so configured and so positioned in the housing that its end 96 contacts the housing 3 to prevent inward movement of the end of the belt carrier assembly 31 having the cam bearings 42. Tightening of the belt 32 serves to lock the key 56 in place between the keyways 52, 54. Once the tong 3 has achieved the configuration shown in Fig. 6, a bolt or shaft can be inserted through a hole 68 which extends through the rotary element 16 and into corresponding holes (not shown) in the bottom and top brake plates 18, 20 thereby permitting reversal of the tongs to rotate the pipe 8 in a direction opposite to that in which it was previously rotated. This is more efficient than removing the belt carrier assembly 31 from its mounting with pivot pin 38 through hole 74 and then emplacing it over hole 68 and inserting the pin 38 therein (although this mode is viable). It will be appreciated that adjustment of the brake bands 77, 79 and adjustment of the length of the belt 32 can affect the point at which the tong 3 first begins to rotate the pipe 8, i.e., depending on these adjustments pipe rotation can be effected, for example, when the cam rollers 40 contact any desired portion of the cam surfaces 26; when the belt carrier assembly 31 reached any desired point in its rotation about the pipe 8; or when the cam rollers 40 have nested in the cam nesting surfaces 78. It should also be noted that entry of the cam rollers 40 into the cam nesting surfaces 78 does not result in a loosening of the belt 32 since the belt 32 is being further tightened around the pipe 8 and the spacer bolts 58 when the cam rollers 40 enter the cam nesting surfaces 78. The jaw 30 may be mounted directly on the belt anchor assembly 21 as shown. Alternatively, it may be mounted on the top brake plate 20 extending upwardly and/or downwardly therefrom. Alternatively, or in addition, it may be mounted on the bottom brake plate 18 extending upwardly or downwardly therefrom. The belt 32 may conveniently be made from aramid fibre or KEVLAR (Registered Trade Mark) which are useful with premium tubulars, softer metals, and softer materials such as fibreglass. However, belts made from metal chain links may be used with, for example, hard metal pipes or casings. If desired, the high friction material 64 may extend outwardly from the jaw 30 to encompass more of the pipe 8. In such a configuration the high friction material may be disposed between the pipe 8 and the belt 32 when the belt 32 wraps around the pipe 8. Furthermore, as shown in Fig. 6, the belt 32 does not wrap completely around the pipe 8, but with suitable disposition of idler shafts, e.g., shaft 62, more (or less) of the belt 32 can be disposed to contact the pipe 8 (or an intermediate friction member).

Claims: Claims : 1. . , An assembly for use in a tong (2) having a housing (3) and a rotary element (16) rotably mounted in said housing (3), said assembly comprising: a) a belt anchor assembly (21) which comprises a body; b) a belt carrier assembly (31) which can be mounted on said rotary element (16); and c) a belt (32) extending between said belt anchor assembly (21) and said belt carrier assembly (31); characterized in that: said assembly further comprises at least one jaw (30) for facilitating gripping a pipe (8). 2. An assembly as claimed in Claim 1, characterized in that said jaw (30) is mounted on said belt anchor assembly (21). 3. An assembly as claimed in Claim 1 or 2, characterized in that said body of said belt anchor assembly (21) is provided with a cam surface (26) and said belt carrier assembly (31) is provided with a cam follower (40), the arrangement being such that, in use, rotation of said rotary element (16) carries said belt (32) around a pipe (8) in said tong (2) until said cam follower (40) engages and moves along said cam surface (26), whereafter said belt anchor assembly (21), said belt carrier assembly (31), said belt (32) and said rotary element (16) rotate with said pipe (8). 4. An assembly as claimed in Claim 3, characterized in that the cam surface (26) on the belt anchor assembly (21) includes a cam nesting surface (78) for receiving said cam follower (40). 5. An assembly as claimed in Claim 4, characterized in that, in use, said cam nesting surface (78) prevents said cam follower (40) from proceeding 11 past said cam nesting surface (78). 6. _, An assembly as claimed in any preceding Claim, characterized in that said belt anchor assembly (21) includes a belt holder which comprises: a) a belt anchor shaft (46) having a top flange (50) and a bottom flange (48), said top flange (50) and said bottom flange (48) each having a keyway (54, 52) therein, said keyways (54, 52) being substantially aligned so that, in use, a key (56) can pass through both said keyways (54, 52) and a loop at one end of said belt (32). 7. An assembly as claimed in Claim 6, characterized in that said belt anchor shaft (46) is rotatable with respect to said belt anchor assembly (21) so that, after positioning of said key (56) in said keyways (52, 54), said belt anchor shaft (46) can be rotated to tighten the belt (32) and secure the key (56) in place. 8. A tong, characterized in that it is provided with an assembly as claimed in any preceding Claim. 9. A tong as claimed in Claim 8, characterized in that it comprises drive means (4, 5, 6) for rotating the rotary element (16). 10. A tong as claimed in Claim 8 or 9, characterized in that said belt anchor assembly (21) is secured to at least one brake plate (18, 20) which is inhibited against movement by a brake (77, 79). 11. A belt holder for use in a tong (2) having a belt anchor assembly (21) characterized in that said belt holder comprises a belt anchor shaft (56) having a top flange (50) and a bottom flange (48), and a keyway (54, 52) in each of said top flange (50) and said bottom flange (48), said keyways (54, 52) being substantially aligned so that, in use, a key (56) can pass through both said keyways (52, 54) and a loop at one end of said belt (32 ) . 12. A belt anchor assembly (21) provided with a belt holder as claimed in Claim 1. 13. A belt anchor assembly (21) as claimed in Claim 12, characterized in that said belt anchor shaft (56) is rotatably mounted in said belt anchor assembly (21).

Inventors: SCHULZE-BECKINGHAUSEN JOERG ER, SCHULZE-BECKINGHAUSEN, JOERG, ERICH
Applicants: LUCAS BRIAN RONALD, WEATHERFORD US INC, LUCAS, BRIAN, RONALD, WEATHERFORD U.S., INC.
Application year: 1989
Main classification: E21B19
IPC codes: E21B19