US1844378A - Well-pipe clamping apparatus - Google Patents

Description

Feb. 9, 1932.

s. LJCAMPBELL.

WELL PIPE CLAMPING APPARATUS Filed March 12, 1927 2 Sheets-Sheet 1 Feb. 9, 1932.. 5.. L. CAMPBELL 4, 7

WELL PIPE CLAMPING APPARATUS Filed March 12. 1927 2 Sheets-Shunt 2 $.92 .51; if 74/ WA #6 i298. fi 2,,

latented Feb. 9, 1932 UNITED STATES PATENT OFFICE STEW'ART L. CAMPBELL, F BERKELEY, CALIFORNIA, ASSIGNOR TO JOHN GRANT, OF

LOS ANGELES,

CALIFORNIA Application filed March 12,

This invention has to do generally with devices For clamping about and supporting ver- 'lrally iiltending worlc, and is more particularly concerned with means for supporting well-pipe such as isinp drill stem or tubing in a manner to suspend such work from the annual surface.

"this device, as is typical of all devices of the heel nature described above, includes a p all I oil? wedge slips arranged to be nizu illtl) l out of clamping engagement will th worn, the slips in turn being suppi rl ed. when in worh engaging position, in a manner to hold the work in suspension. 1 As is well known to those skilled in the art,

in the operation of usual clamping devices it i 1 necessary actually to raise the work-load in order to role the slips from clamping lent with the work. In contradistinciiill' 1e upper end of the. string, being suphy an elevator and l'ioisting tackle. 1 won the clevatmhoisted to raise the whole on until the load is taken oil the slips. The slips are then lifted out of place by hand and the entire string lowered until its upper just above the clamping means, wherethe slips are reinserted about the pipe the string lowered in a manner to wedge the slips into clamping engagement thereo; eral'ions thw equire actual raising ch time the slips are released and ividual movement oil the sllps each 1927. Serial No. 174,775.

time they are to be drawn clear or reinserted. "the above operations are not only laborious andtime and energy consuming, but also neccssitate extreme care in order to prevent accident. For instance, in lowering the slips about the pipe, it is necessary that there be at least two men to handle the. slips, and they must drop the slips simultaneously in order to check the descent of the string at the proper time, improper dropping of the slip often resulting disastrously both to the equipment and workers, as is well understood by those skilled in the art.

My provision for releasing the load without 'aising it eliminates many of the steps men tioned above and generally increases the efficiency of clamping devices to a marked degree and with obvious advantage.

So far as I am aware clamping devices having this characteristicof load-release Without load-lift, have been provided in but one other instance, such a device being the subject-matter of a patent issued to John Grant, April 6, 1926, No. 1,580,099 on releasable spider. The following difference, however, exists between the device shown in the patent and the device now under consideration. In the patent, the slips are allowed to move away from the work without lifting the latter, by virtue of drop ping the slip-supporting ring away from the slips, while holding the slips up, so that the slips are free to move radially outward and clear of the pipe; there is involved a momentary transfer of the load thrust from the sup porting ring to the slips themselves by virtue ol the lowering of said supporting means. In the present device, the sllps are allowed movement away from the pipe without such load transfer by virtue of the slip-supporting means being mounted for movement radially outward from the pipe, or, in other words, by being backed ol'l' horizontally from the pipe. To allow for this, the slip-supportin means is made up of units movable individua ly with respect to the main or body member support of the device. he slips and the slip supporting means may each be considered as a radially expansible and contractible ring of elements about the work, and I provide means for moving them positively toward the work,

said means being releasable in order that the rings may be allowed free movement radially away from the work, at the will of the operator.

An important feature of such slip movement resides in the fact that the slips may be swung or moved over the body support in a manner fully to clear the work-taking bore, it following that the slips do not haveto be lifted out or reinserted manually, as is true of usual clamping devices, thus reducing the labor and time of each clamping and unclamping actuation to a minimum, and eliminating the danger of loose slips; about the ring. This danger is a real one, as it is a matter of somewhat common occurrence for loose slips to be accidentally'kicked into the well bore, thus entailing costly fishing jobs.

Furthermore, the means for radially contracting the rings is such that all the slip elements may be moved either inwardly or outwardly simultaneously, it thus being assured that downward movement of the pipe may be checked at the proper instant and that the individual slip elements are rendered fully releasable at the same instant.

l/Vhile my invention is applicable to any type of body support such as usual spiders mounted stationarily over the well bore, it may be used to particular advantage in connection with rotary tables. This advantage is gained both by reason of the fact that the slips and the slip-supporting means may be used alternately with the usual driving bushing without hampering the efliciency of either and because the power normally at hand for rotating the table during boring operations may be applied most effectively to the means for alternately moving the slips to the work and allowing them freedom of movement away from the work. However, this point may be discussed more fully and to better advantage in the following detailed specification, wherein further objects and novel features will be made apparent.

Reference will be had to the accompanying drawings in which: i

Fig. 1 is an elevation of a device embodying my invention shown in connection withrconventionally illustrated hoisting means for the work; r r

Fig. 2'is an. enlarged plan section on line 22 of Fig. 1; r

. Fig. 3 is a section on line 33 of Fig. 2;

Fig. 4 is a section on line 4:4: of Fig. 2; 1 Fig. 5 is a view similar to Fig. 2 butshowing the slips in clamping position;

Fig.6 is a section on line 6-6 of Fig. 5;

Fig. 7 is a fragmentary sectionon line 77 I of Fig. 5;

Fig. 8 is a fragmentary section on line 8-8 of Fig. 5;

Fig.- 9 is a fragmentary view showing a variational form of slip-support;

Fig 10 is a section on line 10l0 of Fig. 9;

nation, it is not a limitation on certain aspects of the invention, for it may as well be adapted to apparatus utilized solely for supporting work, for instance, a spider.

In the drawings I have shown a supporting body generally indicated at 10 and including a ring-shaped base 11 mounted on sills l2 and supporting a rotary table 14 for rotation about a vertical axis. The table is adapted to be revolved in the usual manner from power shaft 15 through bevel gears 16, 17,

the latterbeing provided on the underside of the overhanging rim 17a of the table. Preferably, though not necessarily, at the upper end of sleeve portion 18 of the table, which portion preferably has peripheral hearing at 19 in base 11, there is provided a bushing 20 having an annular'flange 21 at its upper end. This bushing has tight fit within the table and the upper face of its flangeis substantially flush with table-topQQ; consequently,'the bushing rotates with, and may be broadly considered as a part of, the table and the upper face of flange 21 may be con sidered as a partof the table face.

The table has a vertically extendin axial bore 23 adapted to take work W. In Figs. '1, 2 and 3, wherein the slips are shown free of the work or in inoperative position, work W is in the form of a well-pipe supported from above by elevator E in engagement with the pipe collar C. The elevator, in turn, is suspended by bails B from a hoisting hook H, usual tackle (not shown) being utilized for hoisting or lowering away the elevator in the usual manner.

Mounted for substantially horizontal movement on top the table are provided a plurality of slip-supporting members or carriers 24, said carriers being movable substantially radially with respect to the axis of bore 23 over the table-top. I have shown and will describe the particular type of and mounting for the carriers, and will also describe a particular method of applying wedge slips to saidcarriers. However, it is to be distinctly understood that the invention, considered in its broader aspects, is in no way limited to the particularities set forth, for they are specified merely that a thorough understanding may be had of a preferred construction, from which may be gained knowledge of the prin-- ciples of the broadly considered invention. For instance, broadly considered, the invention contemplates the movement of the slipsupporting means as movable substantially radially with respect to the work axis into and out of engagement with the work. The means for guiding the members through the predetermined path of movement may be of any suitable nature and still lie within the scope of the invention, though I have here shown a mounting wherein the carriers are adapted to be pivotally connected to the table for oscillatory movement towards and away from said axis. Nhile, in following their paths of oscillatory movement, the carriers do not travel exactly along radii extended from the work axis or the axis of the work-taking bore, they substantially follow such radii and, therefore, for the purposes of description and of the claims, they may be considered as moving substantially thercalong. This view will be taken throughout the remainder of the description as well as in the accompanying claims.

Since the individual supporting members or carriers 2% may be identical with one another and since their mounting may be the same, I will describe but a single carrier and its mounting in detail. A given carrier 24 may be considered as an arm or lever pivoted on the table for horizontal oscillatory movement thereover mat a pivot pin 25, said pins prcterably bein naked in sockets 26 whereby they may be easily removed from assembly with the table. As will be hereinafter made apparent, pins also serve as driving connections between the table and the slip carriers. the carriers, through their pivots 25, mounted directly on bushing flange 21, which is considered as a part of the table.

The given arm 24, thus pivotally connected at 525 for horizontal oscillatory movement, has at opposite sides of its free end 28, or, ex-

r pressed otherwise, at a point along its axis spaced from its point of pivotal connection, a cam nose 29 with an arcuate cam face 30 which is substantially concentric with bore 23 or the axis of rotation of work V, and a downwardly and in ardly inclining wedge '0. 211 which is substantially arcuate, as wed in plan. Pin 25 is so located and arm Ell is of such effective length, that oscillatory movement of the arm moves its free end substan i: lly radially with respect to axis A of bore 2? and work W.

Mounted on carrier 2% is segmental wedgeslip 32, the outer arcuate wedge face 33 there of inclinii'ig inwardly and downwardly and being substantially complementary to carrier face 31; while the opposite, substantially vertical face 34 is preferably serrated or toothed at in the usual manner in order to present a proper pipe engaging or gripping st are. tillip segment has an outwardly extending horizontal flange 86 which overlies and is normally vertically spaced from the top face 37 of carrier 24, a bolt 38 extending with loose fit at 39 through the flange and into connection at 40 with the carrier. A

compression spring 41 encircles bolt 40 be tween the underside of the flange and face 37, tending yieldably to hold the slip at its upper limit of travel along the bolt, which limit is established by the downwardly facing shoulder presented by the head of the belt. a

It will be seen that due to the engagement of wedge fa es 231 and 33, downward movement of the slip with relation to the carrier is adapted to move the slip radially with respect to the carrier toward axis A, the loose lit between the bolt and slip-flange allowing such movement.

The several pivot pins 25, or centers of oscillation of the individual arms, are arranged in a circle about axis A and are spaced angularly from one another. Therefore, with the slips movable simultaneously and radially inwardly or outwardly toward or from axis A, the several carriers taken together as a group and the several slips taken together as a group may be considered as rings of elements arranged about axis A and capable of substantially radial contraction and expansion, the ri' gs being radially contracted to bring the slips into engagement with the work and then being capable of radial expansion away from the work.

lit is thus apparent that the individual slips and their carriers are movable horizontall y toward and away from the work without vertical movement. This is in direct c011- tradistinction to foregoing devices wherein the slips are movable radially from the Work only by virtue of prior relative vertical movement between the slips and their supporting members.

lVhile any suitable means may be provided. for radially contracting the ring of slips and then allowing its radial expansion, 1 have shown a particular means which is preferable due to its simplicity and general effectiveness, 21 single member being adapted to cause equal and simultaneous inward movement of the slips and to release all. of said slips simultaneously to allow them to have outward radial movement. For this purpose, I provide a cam ring 42 which mounted on the table top so as to be capable of relative rotation with respect thereto. \Vhile the manner of supporting this ring and holding it "from lateral displacement is not controlling on the invention, I have here shown the ring position-ed horizontally by the upturned marginal, annular flange -ll on table 14-, which flange takes the ring with sliding fit within its bore. l Vhile it is not essential, I also preferably provide releasable means for holding the ring against upward vertical displacement, said means being formed conveniently by passing bolts ll through flange 48 into the annular groove provided about the periphery of the ring. The bolts, of course, have loose fit with the ring so they-do not tend to bind same andinterfere with its free rotation.

Ring 42 is provided with inwardly-extend ing cams 46, there being one cam for each carrier 24, and the several cams being spaced apart angularly and equally thus providing relieved portions or recesses 47 between each cam'and the next one on each side thereof. The major extents 48 of the inwardly presented cam faces are arcuate, as viewed in plan, and, complementary to nose faces 30. Preferably, though not necessarily, faces 48 are substantially concentric with bore 23 or with the axis of rotation of work W and are of appreciable angular extent and extending from the defining faces of recesses 47 to faces 48 are the inclined cam faces 49, though the drop-off. ends of the cams which will be at one side or the other thereof depending upon the direction of rotation of the table may be relatively abrupt, as indicated at 50.

Cams 46 and recesses 47 are so arranged that when the carriers are in the positions of Fig. 2, slips 32 are well clear of or backed away from work w l while, when the ring and table are relatively rotated to the positionof Fig. 5, cam noses 48 have ridden up inclines 49 in a manner to force the carriers radially inward to bring the slips into engagement with the work, and as long as faces or noses 29 are in engagement with cam faces 48, the supports and slips are held from outward radial movement from such operative position and the slip carriers and cam ring may be considered as self locked in operative positions.

As a convenient means for setting uprelative rotation between the cam ring and table I provide a stationarily supported post 51 on one of the sills 12, and a radially extending lug 52 on ring 42. Either, or both the pin and lug (which form, in effect, coacting shoulders on the sill and ring) may be moved from operative position when occasion arises for using the table without the slips. It will be seen that with lug 52 in engagement with till post 51, the ring is held against rotation in a clockwise direction, as viewed in Figs. 2 and 5, when the table and hence the supporting members and slips are moved in said directlon by virtue of rotation of drive shaft 15, pins 25 providing a drive connection between the table and carriers 24 whereby the latter are drawn circumferentially about axis A during the described movement of the table. It follows, that step by step rotation of the table through angles of predetermined extent, alternately causes the carriers to move radially inward to bring the slips into engagement with work of given diameter and to hold them against outward-radial movement and then to remove the backing (cams 46) from behind the carriers so they are free to move the slips'radially outward from engagement with the work. It will be obvious that it requires only a partial revolution of the table to move the carriers completely and simultaneously inward or to release said carriers simultaneously so they may be backed horizontally away from the work. 1

Before describing the releasable means preferably provided for limiting the angular extent of table movement during certain phases of operation, I will set forth a typical operative cycle of the device.

First assume that the elements be in the position indicated in Figs. 1, 2 and 3, and that the load of pipe W be taken entirely by elevator E. In this condition, the slip carriers are backed away sufficiently to hold the slips out of operative engagement with the work, it following that springs 41 are holding the slips in their uppermost position (Fig. 3). If it now be desired to clamp the work to relieve the load from the elevator, the table 14 is rotated to bring carriers 24 into the position of Fig. 5. The inward radial movement ofthe carriers forces the slips radially inward into engagement with pipe W. The elevator E is then lowered away and the pipe, by virtue of its frictional engagement with the slips, augmented by the serrated faces 34 of the latter, serves to carry the slips clownwardly toward or inwardly into the position of Fig. 6, this movement wedging the slips tightly between the carriers and pipe by virtue of the coaction between wedge faces 31 and 33. This wedge action contracts the ring of segmental slips closely about and into clamping relation with the pipe so the pipe load is thereafter taken by the supporting member and table through the slips, whereupon the elevator may be-freed from the work. Of course, springs 41, due to their interposition between faces 37 and flanges 36, in their compressed state limit the downward movement of the slips with relation to their supporting members. i

When occasion arises for releasing the slips from the pipe, at which time the pipe load is adapted again to be supported by an elevator, table 14 is rotated in a manner to bring noses29 into radial alinement with recesses 47, or, expressed otherwise, oif cams 46. The backing behind carriers 24' then being removed, the carriers are free to move radially outward away from the-work; The clamping assembly, considered as a whole, has been put under such strains of radial compression in being clamped to the pipe, that as soon as said compression strains are relieved by reason of the carriers clearing cams 46,the clamping units move radially to expanded position, and springs 41 return the slip elements to raised position.

Generally, the release movement may be described as movement of the carriers and slips substantially radially outward from axis A, or as a horizontal backing. away of the slip supporting means from the work. 'It will be noted that the slips and slip supports are movable to radially expanded position without the necessity of relative vertical movement between them and the table, or of relative vertical. movement between the slips and slip-carriers.

It is desirable. though not necessary, that mean. he provided .o prevent accidental or inadvertent over-rotation oi the table when it is intended to clamp the slips to the work. In other words, as the table rotated to carry nlembers 2i from the position 0t Fig. 2 to that of Fig. 5, it is desirable that releasable means be employed for preventingthe table from being rotated accidentally to an extent carrying members 24.- past cams a6 and thereby allowing; the slips to loosen their hold on the work before such release is intended.

its a convenient, releasable means for limiting the extent 0t ai'lgular movement o1 the table in being; l'fiijtllfitl from slip release position to gripping position, I provide a pawl or detent on one of the rotatable elements, tor instance, on one ot' the carriers. This pawl is mounted on the v1rrier-supported shaft 56 t'or movement about a horizontal axis, and is adapted to extend radially from said carrier in a manner to overlie the top of ring 42. np ularl and equally spaced about ring 42 are inns 57 which present shoulders 58 facing in a direction opposite that of table-rotation, there being one shoulder to each carrier member. The shoulders are so positioned that pawl is in engagement with one of them (Figs. and 8) when the supporting members are in full contact with cams lG. It follows that the table cannot be rotated beyond this position to bring the carriers into alinement with rcce t'i' until pawl 55 has been swung upwardly clear of the cam shoulder this action requiringwillitul effort on the part of the operator. The pawl is adapted to drop back to the position of Fig. 7 as soon as it released by the operator so it is in position to engage the succeeding stop shoulder 58 when the ible is rotated to bring the slips next into work-gripping relation. To forestall efforts on the part of the operator to avoid the safety feature of pawl by rotating it about hull-i all to a position from which it will not drop into operative association with. shoulders 58, I provide a heel member 59 on the pawl which projects rearwardly or inwardly from shall: 56 and is adapted to enthe upper 'lace oil' the carrier in a manit the ctlective end of the pawl 'ungr to vertical or beyond ver to i never on. 9, l0 and, ll 1 have shown a slight red type of slip and carrier assembly. arrier 2hr generally similar to carrier 24 l k and is mounted on the tatile-carried post 25 in the same manner thereon. in this variation, however, slip 3964 has on its rearward inchucd taco 33a a central longitudinally EX- tending lug or guide 84a which is arcuate, as viewed in horizontal cross-section and of greater angular extent than 180. This lug mounted for longitudinal sliding movement through the complementary bore a in carrier Ella. the lug and way inclining at the same angle as do the faces 86a. and 33a of the carrier and slip, respectively. The slip is thus mounted for longitudinal movement with respect to the carrier and has wedge-face engagement therewith in a manner similar to that described in connection with faces 31 and 33. The com plementary arcuate character stics ot lugs 34 and way 35a hold the slip :t'rom horizontal displacement with respect to the carrier. l

There provided a spring 37a anchored at one end 38:: to member 24a and engaging at its free end a downwardly facing shoulder 89o provided on lug 340:. This spring serves normally and yieldably to hold the slip in its uppermost position, downward movement of the slip being definitely limited by engagement oi? the underside of horizontal flange lilo with the upper face of member 24a. It will be apparent that the slip and its car 'ier function in precisely the same manner as do the slips and carriers heretofore described.

In order to produce roller engagement between carriers 2% and cams 46, with the obvious object of reducing frictional resist ance, I may provide for each carrier a roller which is mounted on carrier shaft 61 for rotation about a vertical axis. However, for the sake of simplicity, I have shown but one carrier so equipped. This roller is so positioned that it adapted to take the thrust of cams it when the carrier is moved into alincment therewith and has rolling contact with cam face 48 during, operation of the device (it eours this feature of rolling contact may be embodied in the slips previously described.

In order that the table fashioned in accordance with the above description may be utilized for drivingly supporting the nut or drive bushing whereby the usual drill stem (not shown) is rotated, Without calling for material re-adjustment of parts, carriers 24 are preferably readily detachable from the table. For instance, the driving connection may be such that the carriers may be merely lifted oil pins 25. Then when occasion arises tor using the table for boring purposes, the slip-supports and either or both post 51 and lug 52 are removed. Thereupon, the split drive nut or bushing generally indicated at 62 (Fig. 12) is installed in place of the slips. Ring 1-2 may or may not be removed for it does not interfere with the placement and operation of the drive bushin This drive bushing is preferably made up of two complementary parts 63 and 64, each part comprising a horizontal plate portion 65 from which extend wings 66, the latter being apertured at 67 to take drive pins 25.

The opposed faces 68 of parts 63, 64:, are cut out centrally to form a vertical passageway 69 which is polygonal, as viewed in plan, and proportioned to take a usual kelley or grief pipe whereby drive is adapted to be transmitted from the table to the drill stem (not shown). Plate portions are adapted to rest on top face 37 and they may have, considered together, a centering hub 7 0 adapted to fit within bore 23.

It will "be obvious that the drive nut may be lowered into or lifted from operative engagement with the table with ease and dispatch, the substitution of the slips for the drive bushingbeing made with equal facility. It follows that the apparatus may be adjusted quickly and easily for alternate use as a pipe supporting or pipe rotating means, pins 25, in both instances, serving as the drive connective means.

It will be understood the drawings and description are to be considered merely as illustrative of and not restrictive on the broader claims appended hereto, for various changes in design, structure and arrangement may be made without departing from the spirit and scope of said claims.

' I claim:

1. In a device of the character a rotatable supporting body having a vertical bore adapted totake work, a plurality of slips supported on the body for movement substantially radially towards and away from the axis of the bore, and means actuated by virtue of step-by-step rotation of the body in a given direction for alternately moving the slips substantially radially towards the bore axis into work engaging position and freeing them for movement substantially radially out of work engaging position.

2. In a device of the character described, a supporting body having a bore adapted to take work, a plurality of slips supported on the body for movement substantially radially towards and away from the axis of the bore, a member associated with the body for rotation with respect thereto, and means actuated by virtue of step-by-step relative rotation of the body and member in a given direction for alternately moving the slips sub stantially radially towards the bore axis into work engaging position and freeing them for movement substantially radially out of work engaging position.

3. In a device of the character described, a supporting body ring through which work may pass, slip carriers mounted on the body ring for substantially radial movement to and from the work, wedge slips on the carriers adapted to grip work by virtue of downward movement relative to thecarriers, a cam ring surrounding the carriers and having portions which extend radially inward and present cam faces concentric with the axis of the work, said cam ring having other cam described,

faces which extend outwardly from said concentric faces, all in a manner whereby the cam ring is adapted by virtue of relative rotation of the cam and body rings to move the carriers in toward the work when said other cam faces engage the carriers and to hold said carriers in while said concentric faces engage the carriers, and means for applying power to one of the rings to rotate it relative to the other ring.

4. In a device of the character described, a supporting; body ring through which work may pass, slip carriers pivotally mounted on the body ring for swinging movement to and from the work, wedge slips on the carriers adapted to grip work by virtue of downward movement relative to the carriers, a cam ring surrounding the carriers and having portions which extend radially inward and present cam faces concentric with the axis of the work, said cam ring having other cam faces which extend outwardly from said concentric faces, all in a manner whereby the cam ring is adapted by virtue of relative rotation of the cam and body rings to swing the carriers pivotally in toward the work when said other cam faces engage thecarriers and to hold said carriers in while said concentric faces engage the carriers, and means for applying power to one of the rings to rotate it relative to the other ring.

5. Ina device of the character described, a horizontal rotary table which is centrally apertured to take vertically extending work, slip carriers pivotally mounted 011 the table for horizontal swinging movement to and from the work, wedge slips on the carriers adapted to grip workby virtue of downward movement relative to the carriers, a cam ring surrounding the carriers and having portions which extend radially inward and present cam faces concentric with the work, said ring having other cam faces which extend outwardly from said concentric faces, all in a manner whereby the cam ring is adapted by virtue of relative rotation of the ring and table to swing; the carriers pivotally intoward the work when said other cam faces engage the carriers and to hold said carriers in while said concentric faces engage the carriers, and means for holding the ring against rotation while the table is rotating.

6. In a device of the character described, a rotatable supporting body having a vertical bore adapted to take work, a plurality of slips pivotally supported on the body for horizontal swingingmovement towards and away from the axis of the bore, means actuated by virtue of step-by-step rotation of the body in a given direction for alternately swinging the slips horizontally towards the bore into work engaging position and freeing them for movement radially out of work engaging position.

7. In a device of the character described,

lit]

a rotatable supporting body having a vertical bore adapted to take work, a plurality of sl' supported on the body for movement 5 ibstantially radially towards and away :l rom the axis of the bore, means actuated by virtue o't step-bvstep rotation of the body in a given direct n for alternately moving the slips substantially radially tom rds the bore into work engaging position and freeing them for nniveinent substantially radially out of work engaging position, and releasable means for holding the siuiporting body against rotation in said given direction.

in a device of the character described, a summrtin body ring tnrough which work may pass, work clamping members mounted on the body ring for substantially radial moven'ient to an d from the work, a cam ring :-:urr mnding ill members and having portitms which extend radially inward and present cam faces (ZOIlL'KDtI'lC with the axis of the work, said cam ring having other cam faces which extend outwardly from said concentric faces. all in a manner whereby the cam ring is adapted by virtue of relative rotation (Ill the cam and body rings to move said members in toward the work when said other cam tacos engage the members and to hold said members in while said concentric tacos engage the members and means for applying power to one of the rings to rotate it relative to the other ring.

9. in a device of the character described, a supporting body ring through which work may pass, work clamping members pivotally mounted on the body ring for swinging movement to and from the work, a cam ring surrounding the members and having portions which extend radially inward and present cam iaces concentric with the axis of the work, said cam ring having other cam faces which extend outwardly from said concentric Faces, all in a manner whereby the cam ring is adapted by virtue of relative rotation of the cam and body rings to swing said membore in toward the work when said other cam Faces engage the members and to hold said members in while said concentric faces enthe members, and means for applying power to one of the rings to rotate it relative to the other ring.

10. in a device of the character described, a supporting body rin through which work may pass, a cam ring associated substantially concentrically with the body ring, work clamping membr-a's within. the cam ring, pivotal connections between the body ring and nu'embers, said cam ring being adapted by rotation relative to the body ring to engage the members and thereby swing them at their giivotal connections in toward the work, and means for applying power to one of the rings to rotate it relative to the other ring.

ll. In a device of the character described, supporting body ring through which work may pass, a cam ring associated substantially concentrically with the body ring, work clamping members within the cam ring, pivotal connections between the body ring and members, said cam ring being adapted by rotation relative to the body ring to engage the members and thereby swing them at their pivotal connections in toward the work, said pivotal connections being circumferentially offset from the points of cam and ring engagement, and means for applying power to one of the rings to rotate it relative to the other ring.

12. In a device of the character described, a supporting body ring through which work may pass, a cam ring associated substantially concentrically with the body ring, a series of angularly spaced cam portions extending radially inward from the cam ring, work clamping members within the cam ring and movable substantially radially into engagement with and away from the work, means drivingly connecting said members to the body ring, and means for holding said cam ring stationary while the body ring is rotated, a given clamping member being engageable successively with the cam portions when the body ring is rotated in a given direction, and said cam portions each being adapted to engage and move said clamping member into engagement with the work.

In witness that I claim the foregoing I have hereunto subscribed by name.

STEWART L. CAMPBELL.

Images