Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS2117599 A
Publication typeGrant
Publication dateMay 17, 1938
Filing dateAug 26, 1936
Priority dateAug 26, 1936
Publication numberUS 2117599 A, US 2117599A, US-A-2117599, US2117599 A, US2117599A
InventorsBowen George W
Original AssigneeS R Bowen Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Inside casing cutter
US 2117599 A
Abstract  available in
Images(2)
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

May 17, 1938. G. w. BOWEN INSIDE CASING CUTTER Filed Aug. 26, 1936 2 Sheets-Sheet 1 HA 1 emu 134 May 17, 1938. G. w. BOWEN INSIDE CASING CUTTER Filed Aug. 26, 1936 2 Sheets-Sheet 2 Patented May 17, 1938 r 2,117,599

UNITED STATES PATENT OFFECE INSIDE CASING CUTTER George W. Bowen, Houston, Tex., assignor to S. R. Bowen 00., Huntington Beach, Calif., a corporation of California Application August 26, 1936, Serial No. 97,911

12 Claims. (Cl. 164--0.4)

This invention relates to devices for cutting VII, VIII--VIII, IX-IX, X-X, and XI-XI, off pipes within wells and more particularly to respectively, of Fig. 2. What are known as inside pipe cutters or casing Referring first to Fig. 1, there is shown a pipe cutters in which the tool is lowered on a drill l within which is mounted a cutter in accordance pipe down the well and into the pipe to be out with the invention shown'suspended on the lower and there actuated to sever the pipe in response end of a string of drill pipe 2. Thus the lower to predetermined actuating movements of the end of the drill pipe 2 (referring to Fig. 2) is drill pipe from the surface. threaded into the upper end of a coupling mem- An object of the invention is to provide an inher 3 which in turn is connected by tapered screw side casing cutter particularly adapted to enter threads 4 to the upper end of an upper arbor 5. 10 and sever a pipe the upper end of which is This upper arbor 5 extends downwardly for a located a substantial distance below the upper substantial distance and is connected at its lower end of the well, and to give an indication at the end by thr ads 6 to the upper end of a. lower rf w h pp r end f h p p i reached arbor 1, the latter extending clear to the lower and entered. extremity of the device where it terminates in a 1.)

Another j t of the v nt on s 170 PrOVide guide cap 8, the latter being threaded onto the a cutter wh h m y e w re into a p p to e lower end of the lower arbor and secured in place actuated to sever P p and h be autoby a set screw 9. The arbors 5 and 1 function matically rendered inoperative in response to an as a single unit in operation. the device and upw d D11 w e y e 13001 y he S q y are made in two sections only for convenience in 20 raised, lowered or turned without again actuatmanufacture and assembly ing the Cutter- Adjacent its upper end the upper arbor 5 is Another j t of the inVentiOn is t0 provide enlarged so that its outer surface is substantially a positive and fool-proof releasing mechanism for cylindrical and flu h t the outer surface f release of the cutters when the levelin the well the lower portion f the couphhg 3 and is pros 25 i5 reached at Which the pipe is to he Severedvided with vertical radially extending slots H Another Object to Provide a Simple, and in which are mounted knives [2. Each. knife l2 fectwe mounting for the knives cutters in a is dimensioned to fit freely within its slot and is inside pipe cutting tool and to provide an eifecprovided with a circumferentially expanded head tive spring mechanism for normally retracting |3 at the upper end, which fits into a recess the knivesvided therefor in the arbor, thereby preventing Another object is to provide a construction in the knif from dropping downwardly out f postwhich the anchoring slips may be actuated to tion A bearing bushing M is provided in the anchor the device at a desired point in the pipe upper e of each Slot f r supporting the knives by merely lowering the device a drill string against upward movement, these bushings havto the desired level and then rotating the drill ing substantially semicylindrical bearing surfaces string in one direction while maintaining it at which engage the upper ends f the knives a wnsiant height a Each knife has a bit [5 thereon at the lower Various other objects and specific features of end which is adapted to cut through a pipe in the invention W become a a from the response to movement of the lower end of the 40 tailed description which follows and it is to be k ife outWaI-Ouy in swinging movement about the understood that the scope of the invention is to upper end as a pivot To n retain the be limited only in accordance with the claimslower ends of the knives within the slots out of Referring to the drawings! cutting position, a straight spring member E6 is 1 is a "ertical elevation View Showing an secured to the upper end of each knife and pro- 45 inside pipe cutter in accordance with the invenjects therefrom through an aperture il in the tion position within a pipe, the latter being shown associated bushing It and into a recess 18 proin section; vided in the arbor 5. These recesses l8 are com- Fig. 2 is a detailed View partly in section shoW- pletely enclosed by the coup-ling member 3. The ing the upper portion of the cutter structure upper end of each of the spring members 18 rests 50 which is disclosed in full in Fig. 1; against the arbor 5, thereby resiliently urging the Fig. 3 is a detailed view partly in section showlower ends of the knives inwardly. ing the lower end of the mechanism; and Positioned immediately below the knives l2 and Figs. 4, 5, 6, 7, 8, 9, 10 and 11 are section views slidably mounted on the arbor 5 is an expander taken in the planes l'V-IV, V-Y, VI-VI, VII- head l9 having a plurality of knife seats 20 there- 55 on and a plurality of recesses 2| therein. The recesses 2| are positioned between the knife seats 20 and alongside thereof for a purpose to be described later. The expander head I9 is provided with a threaded shank 22 on the lower end thereof, which is adapted to be screwed into a connecting member 23. The connecting member 23 is slidable vertically on the arbor 5 but is capable only of limited rotary movement with respect thereto. Thus the connecting member 23 is provided with splines 24 (Fig. 5) which normally engage against splines 25 on the arbor so that in response to counterclockwise rotation (with respect to Fig. 5) of the arbor 5 the connecting member 23 and the expander head !9 are forced to rotate with the arbor. In this position, in which the splines 24 and 25 engage as shown in Fig. 5, the knife seats 20 on the expander head l9 are in alignment with the knives l2 so that in response to downward movement of the arbor 5 and the knives with respect to the expander head I9, the lower ends of the knives 12 will ride down on the knife seats 20 thereby forcing the bits l5 outwardly into engagement with a pipe to be out. However, after the knives have been fully expanded to force the bits I5 completely through a pipe, it is desirable to be able to quickly retract the knives; and in accordance with the present invention this is done by permitting the arbor 5 and the knives [2 to rotate with respect to the expander head IS in response to sufiicient .upward movement of the expander head l9 to fully expand the knives. This result is obtained by so positioning the upper ends of the splines 25 on the arbor with respect to the lower ends of the splines 24 on the connecting member 23 that these splines disengage in response to a predetermined downward movement of the arbor with respect to the connecting member 23.

As previously mentioned, the head H] is attached to the member 23 by the threaded shank 22. The cooperating threads on the shank and head are dimensioned to fit tightly so that the parts remain in whatever relative positions they may be set. This makes possible the vertical adjustment of head i 9 relative to member 23 to vary the extent to which the knives will have been opened at the time the splines 25 and 24 disengage.

Of course, in order to effect downward motion of the arbor 5 relative to the expander head I9 and connecting member 23, it is necessary to anchor the latter element against downward movement. To this end, there is positioned surrounding the arbor 5 below the connecting member 23 a spear head 26 which is freely rotatable on the arbor 5 and is provided with slip seats 21 on which are mounted pipe engaging slips 28. Downward movement of the connecting member 23 with respect to the spear head 25 is prevented by bearing rings 29 interposed therebetween and relative rotation between the spear head 25 and the connecting member 23 is impeded by friction shoes 30 which bear against the surface of an annular groove in the connecting member 23 and are mounted on spring strip members 3| which are secured at their lower ends to the spear heads 26 as by screws 32. The slip seats 21 are inclined upwardly and outwardly so that when the slips 28 are moved upwardly along the seats they are forced outwardly into engagement with the pipe I, thereby firmly locking the spear head 25 against either downward or rotary movement with respect to the pipe. It will be obvious that when the spear head 26 is anchored to the pipe,

the previously mentioned knife expanding movement of the arbor 5 with respect to the expander head l9 may be obtained by merely lowering the arbor on the drill pipe 2.

However, before the spear head 26 can be anchored the slips 28 must be moved upwardly along their seats and to this end each slip 28' is connected by a slip rein 33 to a housing member 34 which is slidably mounted upon the lower arbor l. The upper ends of the reins 33 are con nected to their associated slips by bending the upper ends of the reins outwardly into recesses 35 provided therefor in the rear faces of the slips. The lower ends of the reins 33 are rigidly secured to the housing 34 by screws 35.

To normally retain the slips in retracted position (as shown in Fig. 2) the lower arbor l is provided with downwardly deflected ratchet threads 31 within the housing 34 and several split nut sections 38 having ratchet threads adapted to cooperate with the threads 31 are mounted in pockets 38a in the housing 34. Each pocket 38a has sufiicient depth radially to permit movement of the split nut section therein completely out of engagement with the ratchet threads 31 but is constantly urged inwardly toward the threads 3! by a straight spring member 39, the upper ends of these various spring members 39 being rigidly secured to the housing by bolts 48. The tension of the spring members 39 urges the split nut sections 38 inwardly toward the lower arbor l but permits the nuts to move outwardly and slip past the threads on the arbor in response to upward movement of the arbor. The lower face 34b of each pocket 38 is inclined inwardly and downwardly at an angle of 30 and the lower face of each nut section is similarly inclined. The inclined bottom faces on the nut sections and the inclined bottom walls on the recesses cooperate to insure positive engagement of the ratchet threads on the nuts with the ratchet threads on the arbor to prevent downward movement of the arbor with respect to the housing while permitting disengagement of the threads in response to upward movement of the arbor with respect to the housing.

To impart upward force to the housing 34 to set the slips 28, the housing 34 is connected by a helical spring 4| surrounding the lower arbor 1 to a sleeve 42 which is slidably mounted on the arbor 1 therebelow. Sleeve 42 is provided with pipe engaging bow springs 43, these springs being rigidly attached to the sleeve 42 at their lower ends but having their upper ends free to permit radial expansion and contraction of the center portions of the bow springs. The bow springs 43 are provided with notches 44 thereon to increase the resistance of entry of the springs into the upper end of a pipe.

For a purpose to be described, later, the arbor 1 is reduced in diameter adjacent its lower end to provide a shoulder 45 and the sleeve 42 has mounted thereon intermediate the springs 43 a plurality of springs 46 which are anchored to the sleeve 42 at their upper ends by screws 41. These springs 45 are relatively short, being only about half the length of the springs 43, and have their lower ends inturned and fitted into recesses or openings 48 in sleeve 42. The lower wall of each recess 48 is extended outwardly to form an outwardly and upwardly extending lip 49 which engages the lower end of the associated spring 45 and limits outward movement of the spring. The tension of each spring 46 normally maintains its lower end against the lip 4%, in which position the extreme inner end of the spring is clear of the shoulder 45.

The device is operated as follows: Assuming that the cutter is secured to the lower end of a drill string 2, it is first lowered into the well with all of the parts shown in the positions indicated in Figs. 1, 2 and 3. It will be observed that the split nut sections 38 are engaging the threads of the screws 37 on arbor 1 adjacent the lower end of the latter, thereby maintaining the housing 34, reins 33 and slips 28 in lowermost position in which the slips are retracted so that they do not project beyond the outer periphery of the spear head 26. Furthermore, the slips 28 engage against the lower end of the spear body 2i holding the latter in lower position and the spear body in turn acting through the springs 3!, the friction elements 3i] and the connecting member 23 hold the expander head IS in lower position in which the knife seats 25 on the expander head are below the knives l2, under which conditions the knives are fully retracted.

As the device is lowered into the well, it will finally reach and enter the upper end of the pipe to be out, being guided into the pipe by the guide member 8 on the lower end of the arbor l. The guide member 8 is dimensioned to enter freely within the pipe to be cut but the bow springs 43 project outwardly substantially beyond the edge of the pipe so that they catch on the upper edge of the pipe and the notched portions 44 bind on the edge of the pipe and set up considerable opposition to the entry of the springs into the pipe. This informs i the operator at the surface that the pipe has been reached. Having this information; the operator then forces the tool into the pipe by applying more weight to it and continues to lower the tool until the point is reached at which it is desired to sever the pipe. During this downward movement of the tool through the pipe the bow springs 433 are expanded tightly against the inside surface of the pipe and offer substantial frictional resistance to downward movement, thereby compressing the coil spring 4! to a substantial degree. It will be observed that at this stage the compression of the spring 4! is produced without producing any upward movement of the housing 34 because the split nut sections 38 are engaging the threads 3'! on arbor l. However, as a result of the frictional resistance of the bows 43 upon initial entry of the springs into the upper end of the pipe, the sleeve 62 is forced upwardly along the arbor carrying the lower ends of the springs 45 above the shoulder 15 so that although, upon entry of the springs it into the pipe, they are bent inwardly the lower ends of these springs 46 cannot prevent upward movement of the housing 42 with respect to the arbor because of the fact that the ends of the springs 4t are above the shoulder 45 resting against the smooth portion of the arbor E thereabove.

When the operator has lowered the tool to the point in the pipe where he wishesto sever the latter, he stops downward motion of the drill.

string but does not retract the drill string. Therefore, the tool is stopped'with the spring 4! compressed. The operator then rotates the drill string to the right. This rotates the arbors and "i and the rotation of the threaded portion (ill of arbor 1 with respect to the split nut sections 38 (the latter being restrained from rotation by its connection through spring 4| to the housing 34 to be slowly moved upwardly along the arbor T by the spring 4!, thereby carrying the slips 28 upwardly along their seats 21 on the spear head into engagement with the pipe. If this motion is not sumcient to disengage the nuts 38 from the threads 3? the continued rotation of the arbors merely causes the split nut sections 38 to slip over the ratchet threads 31. Rotation of the drill string is preferably continued until the spring ii is fully expanded, which usually results in the nuts 38 being completely released from the threaded section 31 of the arbor, after which the drill string is lowered to force the knives l2 downwardly onto the knife seats 26 on the expander head E9 to expand the knives against the casing. During all this time the string maybe rotated and by applying suificient weight to the arbors 5 and I the knives will be gradually forced outwardly by the knife seats 2E5 to force the bits l5 into and finally through the pipe, severing the latter. During this stage of the operation the expander head I 9 rotates with the arbor 5 and the knives l2 by virtue of the fact that the splines 25 on the arbor are in engagement with the splines 24 in the connecting member 23 on which the expander head it is mounted. However, when the expander head i9 has been moved upwardly a sufficient distance to fully expand the knives l5, the splines 2a and 25 disengage as hereinbefore described, whereupon the rotation of the connecting member 23 and expander head l9 ceases by virtue of the fact that these members are restrained from rotation by the friction shoes 30. Therefore the arbor and the knives I2 rotate with respect to the expander head I9 until the lower ends of the knives l2 ride oiT of the knife seats 20 into the recesses 25, whereupon the springs I6 immediately retract the knives.

Following completion of a cut in the manner described, the tool may be withdrawn from the well or it may be left in the well during subsequent operations. Thus. for instance, a pipe puller may be mounted on the same string with the pipe cutter to engage and remove the severed portion of the pipe after the cutting operation has been completed in the manner described. In such instances it is often desirable to lock the cutter against subsequent operation so that it can be moved upwardly or downwardly at random through the pipe without setting the slips. The present cutter may be locked against further operation by merely withdrawing the tool upwardly a short distance through the pipe after completion of the operations described. This upward movement immediately disengages the slips 23 from the pipe permits them to fall into retracted position as shown in Fig. 2. During this operation the split nut sections 38 slip down over the ratchet threads on the screw 31' on arbor 1 and by virtue of the frictional resistance of the spring bows 53 against the pipe the sleeve 42 is retracted into full lowermost position on the arbor I, in which position the shoulder 45 is positioned above the lower ends of the springs 46 and the latter are forced inwardly by the pipe to engage against the shoulder 15 and prevent any upward movement of the sleeve 32 on the arbor in response to subsequent downward movement of the arbor 1'. Therefore, following the completion of a cut as described and the upward movement of the tool through the pipe for a short distance, the sleeve 32 is positively locked in lowermost position as long as the tool remains within the sleeve t2) permits the nut sections 38 and the pipe so that the tool can be raised or lowered or rotated to any desired extent without any possibility of again setting the slips and actuating the cutting mechanism. However, if it is desired to produce another cut, the cutter may be immediately restored to its original normal position by withdrawing it from the pipe and again lowering it into the pipe. Upon withdrawal of the tool from the pipe the springs it are released so that their lower ends move outwardly, thereby disengaging the shoulder 65 on the arbor I. This places the entire tool in the closed position shown in Figs. 2 and 3 and by then again lowering the tool into the pipe the operation described may be repeated to make another out.

To simplify the explanation of the invention, it has been explained by describing in detail a particular form of cutter. Obviously many variations may be made in the particular construction described while still employing features of the invention. The invention is therefore to be limited only as to the extent set forth and defined in the appended claims.

I claim:

1. An inside pipe cutter comprising a cutter head adapted to be secured to a drill pipe, a cutter mounted on said head for movement outwardly into active position and inwardly into retracted or inactive position, means normally tending to move said cutter into inactive position, cutter-actuating means including anchoring means associated with said head for moving said cutter into active position in response to downward movement of said head with respect to said cutter-actuating means, and means responsive to upward movement of the device through a pipe for locking the head against subsequent downward movement with respect to said cutter-actuating means while the device remains within said pipe.

2. A casing cutter comprising an arbor adapted to be secured to the lower end of a drill pipe, a spear head slidable on said arbor, an expansible knife on said arbor, means for expanding said knife in response to downward movement of said arbor with respect to said spear head, slips on said spear head mounted for upward and outward movement thereon into pipe engaging position, a sleeve slidably mounted on said arbor below said spear head, means connecting said sleeve to said slips, a shoulder on said arbor, and spring latch means on said sleeve adapted to normally lie out of engagement with said shoulder, said spring latch means being so positioned as to contact and be deformed by a pipe when the device is inserted in said pipe whereby it engages said shoulder on said arbor to prevent downward movement of the arbor with respect to the sleeve, and bow springs on said sleeve for frictionally engaging a pipe and tending to carry the sleeve upwardly on the arbor when the latter is lowered through the pipe.

3. A device as described in claim 2 in which said means for connecting said sleeve to said slips includes a connecting member positively connected to said slips and yieldably connected to said sleeve, with means for releasably locking said connecting member against upward movement relative to said arbor, said yieldable connection between said connecting member and sleeve permitting sufficient upward movement of said sleeve with respect to said arbor and connecting member to carry said shoulder on the arbor below said spring latch means during downward entry of said sleeve into a pipe and maintain the shoulder below said latch means during subsequent downward movement of the sleeve into the pipe.

4. A casing cutter comprising an arbor adapted to be secured to the lower end of a drill pipe, anchor means on said arbor adapted to be anchored within a casing or pipe, a cutter head on said arbor containing a vertical slot for a cutter, a cylindrical upper bearing member having an aperture extending therethrough in the upper end of said slot, a cutter bar mounted in said slot having a cylindrical upper end adapted to bear against said bearing member, a spring bar secured to and extending from the upper end of said cutter bar through said aperture in said bearing member, said arbor having a recess therein into which said spring bar projects, the upper end of the bar engaging the arbor to urge the lower end of the knife bar inwardly into said slot, and knife expander means comprising a wedge member connected to said anchoring means, said wedge member and anchoring means being slidable on said arbor whereby downward movement of the arbor and cutter head with respect to the anchor means forces the lower end of the knife outwardly from the arbor.

5. A casing cutter comprising an arbor adapted to be secured to the lower end of a drill pipe, an expander head slidably mounted on said arbor, anchor means for anchoring said expander head within a pipe against downward movement with respect to the pipe while permitting rotation of said head, a knife on said arbor above said expander head, said knife being pivotally secured adjacent its upper end to said arbor, said expander head having an inclined knife seat thereon adapted to force the lower end of said knife outwardly in response to downward movement of the arbor and knife with respect to said expander head, said expander head having a recess therein spaced circumferentially from said knife seat for permitting collapse of said knife in response to rotation of said arbor and knife with respect to said expander head, cooperating splines on said expander head and arbor, respectively, for normally preventing rotation of said arbor relative to said head, said splines being so positioned relative to each other as to disengage when said expander head reaches a predetermined position relative to said knife to permit rotation of said knife 01f said seat and into said recess, thereby automatically retracting the knife.

6. A casing cutter comprising an arbor adapted to be secured to the lower end of a drill pipe, an expander head slidably mounted on said arbor, anchor means for anchoring said expander head within a pipe against downward movement with respect to the pipe while permitting rotation of said head, a knife on said arbor above said expander head, said knife being pivotally secured adjacent its upper end to said arbor, and said expander head having an inclined knife seat thereon adapted to force said knife outwardly in response to downward movement of said arbor and knife with respect to said expander head, means for releasing said knife from said knifeseat in response to predetermined downward movement of said arbor with respect to said anchor means, said expander head having a threaded extension on the lower end thereof adapted to screw into cooperating threads on said anchor means whereby the vertical position of the expander head with respect to the anchor means may be adjusted by turning the expander head, to vary the range of movement of said knife.

7. A casing cutter comprising an arbor adapted to be secured to the lower end of a drill pipe, anchor means slidably mounted on said arbor for engaging a pipe, a knife on said arbor above said anchor means, an expander head positioned below said knife and having an inclined knife seat thereon adapted to force said knife outwardly in response to downward movement of said arbor and knife with respect to said head, means for releasing said knife from said knife-seat in response to predetermined downward movement of said arbor with respect to said anchor means, and extensible means connecting said head to said anchor for varying the range of movement of said knife.

8. A device as described in claim 5 with frictional means for frictionally interengaging said anchor means and expander head for frictionally resisting rotation of said expander head with respect to said anchor means.

9. A casing cutter comprising an arbor adapted to be secured to the lower end of a drill pipe, a spear head slidable on said arbor, an expansible knife on said arbor, means for expanding said knife in response to downward movement of said arbor with respect to said spear head, slips on said spear head mounted for upward and outward movement thereon into pipe-engaging position, a sleeve slidably mounted on said arbor below said spear head, means connecting said sleeve to said slips, friction means associated with said sleeve for frictionally engaging a pipe within which said device is positioned, said arbor having downwardly directed ratchet screw threads thereon, a split nut attached to said sleeve having upwardly directed ratchet threads thereon adapted to engage said threads on said arbor, and spring means for urging the nut sections into contact with the arbor thread whereby the arbor is free to move upwardly with respect to the split nut and sleeve and is normally prevented from downward movement with respect to the sleeve except in response to rotation of the arbor in one direction with respect to the sleeve.

10. A device as described in claim 9, in which said sleeve includes a housing for enclosing the sections of said split nut and said spring means comprises spring members extending vertically from said nut sections to said housing andattached thereto at their upper ends for supporting said nut sections with respect to the housing.

11. A casing cutter comprising an arbor adapted to be secured to the lower end of a drill pipe,

may be varied.

a spear head slidable on said arbor, an expansible knife on said arbor, means for expanding said knife in response to downward movement of said arbor with respect to said spear head, slips on said spear head mounted for upward and outward movement thereon into pipe engaging position, a sleeve slidably mounted on said arbor below said spear head, means connecting said sleeve to said slips, friction means associated with said sleeve for frictionally engaging a pipe within which said device is positioned, said arbor having screw threads thereon, a cooperating nut attached to said sleeve adapted to engage said screw threads on said arbor for normally preventing downward movement of the arbor with respect to the sleeve while permitting downward movement in response to rotation of the arbor in one direction with respect to the sleeve, in which a spring connection is provided for attaching said friction means to said sleeve, said spring connection being compressible in response to downward movement of said arbor through a pipe to exert a continued upward force on said nut and sleeves during subsequent rotation of said arbor while maintaining the arbor at a fixed level.

12. A casing cutter comprising an arbor adapted to be secured to the lower end of a drill pipe, a knife supported on said arbor for outward swinging movement, an expander head below said knife having an inclined knife-seat thereon for forcing said knife outwardly in response to downward movement of the arbor and knife with respect to the expander head, said head having a recess therein circumferentially spaced from said knife-seat for permitting collapse of said knife in response to rotation of the arbor and knife with respect to the expander head, anchor means rotatable on said arbor, a head-supporting member coupled to said anchor means for vertical movement therewith and rotary movement with respect thereto, cooperating means on said headsupporting member and arbor, respectively, for normally preventing rotation of said arbor relative to said member while permitting such relative rotation in response to predetermined downward movement of said arbor relative to said member, and means for vertically adjustably connecting said head tosaid member for movement therewith whereby the range of outward movement of said knife prior to collapse of the knife GEORGE W. BOWEN.

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US5074355 *Aug 10, 1990Dec 24, 1991Masx Energy Services Group, Inc.Section mill with multiple cutting blades
Classifications
U.S. Classification166/55.7
International ClassificationE21B29/00
Cooperative ClassificationE21B29/005
European ClassificationE21B29/00R2