US2151681A - Perforator - Google Patents

Description

March 28, 1939. o. A. BROWN PERFORATOR Filed June 5 1934 2 Sheets-Sheet l KJVQ fw my @M @52% W M ,wg ...A,.I.,....H@.ja m .0. A Q .m

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March 28, 1939. o. A. BROWN 2,151,681

PERFORATOR Filed June 5, 1954 2 sheets-sheet 2 y 60 23 E b 47 /0 53 Patented Mar. 28, 1939 PATE-NT OFFICE 2,151,681 PERFRATOR Ora A. Brown, South Gate, Calif., assignor to Baash-Ross Tool Company, Los Angeles, Calii'., a corporation of California Application June 5, 1934, Serial No. 129,098

28 Claims.

This invention relates to a well tool and relates more particularly to a perforator for perforating pipe or casingln a well. A general object of this invention is to provide a simple, practical and particularly effective perforator for .forming openings or perforations ina well casing.

Another object of the invention is to provide a perforator of the character mentioned that is positive and dependable in its operation.

Another object of the invention is to provide a perforator for forming openings in pipe or casing in a well that includes a novel and particularly effective means for actuating or projecting the perforating cutter.

Another object of the invention is to provide a perforator of the character mentioned in which the blade or cutter is projected a maximum distance from the body of the tool to fully penetrate or perforate the wall of the well casing.

A particular object of the invention is to provide a perforator whose mode of operation informs the operator of the full actuation of the cutter.

Another object of the invention is to provide a perforator that includes a cutter that is first pivoted or swung outwardly about one axis and is then pivoted or swung outwardly about another axis so as to have eiective angles of cutting or perforating engagement with the casing during its cutting movement and to be projected a maximum or very substantial distance from the body of the tool.

A further object of the invention is to provide a perforator of the character mentioned that is simple and inexpensive of manufacture and easy and convenient to operate.v

Other objects and features of my invention will be better and more fully understood from the following detailed description of typical forms and applications of the invention, throughout which description reference may be had to the accompanying drawings, in which:

Fig.- 1 is a side elevation of the perforator provided by this invention showing it passing downwardly through a pipe or casing. Fig. 2 is an enlarged longitudinal detailed sectional view taken as indicated by line 2--2 on Fig. 1 showing the cutter in its retracted position. Fig. 3 is an enlarged longitudinal detailed sectional view taken as indicated by line 3--3 on Fig. 1. Fig. 4 is a view similar to Fig. 2 illustrating in :full lines the cutter in a partially actuated position and illustrating in broken lines the cutter in a substantially fully operated position. Figs. 5 and 6 are enlarged transverse detailed sectional views taken as indicated by lines 5-5 and 6-6 on Fig. 2. Fig. '7 is a view similar to Fig. 6 showing the cutter in its actuated position in the channel, and Fig. 8 is a fragmentary longitudinal sectional view of a form of the invention in which the channel is inclined.

'I'he perforator provided by this invention includes, generally, a body IIJ, a cutter II carried by the body I0. and means I2 for actuating the cutter.

The body I0 is an elongate member or structure Vprovided in its upper end with suitable means for connecting with an operating string. In the particular case illustrated in the drawings a tapered screw-threaded pin I3 isprovided on the upper end of the body Il) for facilitating connection of the tool with the operating string S. The body I0 is in the form of a frame or carrier for the other parts of the tool and -is constructed and shaped to house the cutter II when it is in its retracted position and to support the cutter for movement during its actuation or projection. The body I0 is provided with v an opening in the form of a longitudinal channel I4. The opening or channel I4 is provided to carry the cutter Il and terminates at points suitably spaced from the upper and lower ends of the body.

A channel member I5 is arranged in the major upper portion of the channel I4. The member I5 lies against the inner wall of the channel I4 and has spaced parallel side flanges VI6 lying against the side walls of the channel. The lower portion oi' the channel or opening I4 is in the nature of a slot extending through the body I0 from one side to the other and the channel member I5 projects downwardly into this slot. A ange or key I1 is provided on the rear of the channel member I5 to cooperate with the body slot and its upper end bears against a downwardly facing shoulder I8 of the body. A block I I9 is arranged in the upper end of the body opening or channel I4 and screws 2n extend throughA openings in the block and the member I5 and thread into the body I0' to attach the member to the body. The block I9 is preferably inset in the side walls of the channel I4 as illustrated at 2| in Fig. 1 of the drawings. Longitudinal ribs or anges 22 are provided on the side walls of the channel I4 at or adjacent the periphery of the body I0. 'I'he anges 22 are preferably of substantially the same thickness as the flanges I6 and the inner surfaces of the flanges 22 are spaced from and parallel with the outer sides of the anges I6 to provide keyways 55- 23 for the purpose to be hereinafter described. The flanges 22 may be welded or otherwise secured to the body III. In the form of the invention being described the keyways 23 and the inner wall of the member I 5 are parallel with the longitudinal axis of the body I0.

In accordance with the invention two curved convex surfaces 24 and 25 are provided on the inner wall of the channel member I5. 151e convex surfaces 24 and 25 are continuations of the inner wall of the channel member I5 and are provided on enlargements 24* and 25 of the member. The lower enlargement 24* projects downwardly beyond the iianges I8 and its surface 24 is curved upwardly and inwardly from the back peripheral surface of the body. The convex surface 24 is curved about the axis or point A. 'I'he upper raised portion or enlargement 25 occurs between the flanges I8 and joins the enlargement 24. 'Ihe convex surface 25 is curved about the point B. In the case illustrated the point B is spaced upwardly and inwardly from the point A and the surface has a radius of curvature substantially the same as that of the surface 24, it being understood that one surface may have a. greater radius of curvature than the other. The convex surfaces 24 and 25 are of substantial circumferential extent and joint one another as illustrated in the drawings. The lower end portions of the flanges I5 have their outer sides curved about the point or axis B as at 21 and then extend downwardly and rearwardly to the back external surface of the body. The inner sides of the flanges 22 have portions or surfaces 28 curved about the point A and surfaces 29 curved about the point B. As the inner sides of the flanges 22 oppose the convex surfaces 24 and 25 their surfaces 28 and 23 are concave. The surfaces 24 and 25 and the other parts Just described 'may be considered as elements of the means I2 for actuating the cutter I I.

'Ihe cutter II is movable from a position en- Sirely within the body I8 to a position where its gaerforating knife or blade projects a substantial distance from the body to form or make a perforation in the casing C. The cutter II is proportioned and shaped to operate or move longitudinally in the body between a retracted and inverted position in the open end of the channel I4 and a horizontal projecting position in the channel member I5. The cutter II includes a base or shank 3D and a knife or blade 3I project-v ing from the shank. The shank 30 has at parallel sides 32 for shiftably or slidably cooperating with the inner sides of the anges I6 and 22. Elongate lugs or keys 33 are provided on the sides of the shank 30 and are designed to move longitudinally in the keyways 23 when the cutter assumes its substantially horizontal projected position. The perforating blade 3l is of reduced width and has a curved lower edge 34 joining a straight outer edge 35 at a point or corner 5I. The outer edge 35 of the blade joins the upper edge of the blade at an abrupt corner 36, which is adapted to cut through or pierce the wall of the casing C when the cutter is actuated.

The inner side of the cutter shank 30 is provided with a concave surface 31 for cooperating with the convex surface 24 and a concave surface 38 for cooperating with the convex surface 24. 'I'he concave surfaces 31 and 38 are adapted to successively cooperate with the surfaces 24 and 25. The lower concave surface 31 has the same radius of curvature as the face 24 and the upper concave surface 38 has the same radius of curvature as the convex surface 25, The surface 38 terminates at its upper end in a dat face 39 which is parallel with the keys 33. The block or shank 38 of the cutter may have comparatively thin wings 40 at opposite sides of the concave surface 31 for passing or engaging the opposite sides of the enlargement 24". When the cutter I I is in its contracted or unactuated position its perforating blade 3| projects downwardly in the body slot or channel I4, its keys 33 are substantially horizontal and its concave face 31 is in cooperation with the convex surface 24. With the cutter in this retracted position the ends 4I of the keys 33 slidably engage or have slight clearance with the concave surfaces 23 of the flanges 22. The outer ends 4I of the keys may be curved to have effective engagement with the concave surfaces 28.

The means I2 for operating the cutter II includes a wedge or wedge block 43 and a tail piece 44 for controlling the operation of the wedge block 43. The wedge block 43 is arranged in the open lower end of the body opening or channel I4 and has a downwardly and outwardly inclined upper surface 45 for cooperating with the curved lower edge 34 of the cutter blade 3 I The block 43 is movable vertically or longitudinally in the body opening or channel I4.

The tail piece 44 includes a mandrel or stem 48 connected to the block 43 and shiftable relative to the body III. T'he stem 45 slidably or shiftably passes through a longitudinal opening 41 in the lower end portion of the body III and has a reduced upper end 43 threaded into an opening in the wedge block 43. A pin 48 extends through openings in the wedge block 43 and reduced portion 48 of the stem to lock the portion 48 against unthreading from the block. While the block 43 may have fiat sides to prevent it from turning in the body, the end portions of the pin 45 may extend into longitudinal slots 50 in the walls of the body I0 to hold the block 43 and stem 46 against turning and to limit their longitudinal movement with respect to the body. The stem 46 projects a considerable distance downwardly from the lower end of the body I0 and is provided at its lower end with a bull nut 5I. Spaced sleeves 52 and 53 are slidable longitudinally on the stem 46 and are connected by a plurality of spaced leaf springs 54. The springs 54 are bowed outwardly to engage the interior of the casing. C. The

springs 54 in engaging the casing C resist movement of the assembly of the springs and sleeves with respect to the casing C. A latch 55 is provided to releasably hold the stem 46 and wedge block 43 against longitudinal movement relative to the assembly of the sleeves and springs 54 when the cutter II is being actuated. The pivoted latch 55 is arranged in a longitudinal recess 58 in the lower portion of the stem 45 and has a downwardly facing shoulder 51. A spring 58 normally yieldingly urges the latch 55 out of the recess 58. The shoulder 41 is adapted to engage the upper end of the sleeve 53 when the stem is moved upwardly with respect to the spring and sleeve assembly.

When the perforator is to be lowered or run into the well the latch 55 is pivoted inwardly against the action of the spring 58 and the assembly of the springs 54 and the sleeves is raised to a position such as illustrated in Fig. 3 of the drawings where the latch is held inwardly through engagement with the interior of the sleeve 53. The tool may then be run or lowered into the well casing C. During the downward movement of the perforator through the casing C. on the lower end of the string S, the springs 54 engage the interior Vof the casing to resist movement of the tail piece assemblyso that the upper sleeve 52 is held up against the lower end of the body I 8 and the assembly is retained in the position illustrated in Fig. 3.V The combined weight of the block 43, stem 48 and bull nut 5| holds the block 43 in the position illustrated .in Fig. 2 of the drawings where its lower end rests on the lower wall 80 of the body opening or channel I4. The cutter II is in its retracted position illustrated in Fig. 2 of the drawings where it does not project from the body to interfere with the passage of the tool through the casing.

When the perforator has reached the desired or required depth it is raised or lifted through the medium of the operating string S. Upward movement of the body I8 causes corresponding upward movement of the stem 48, but due to the engagement oi.' the springs 54 with the interior of the casing the assembly of the springs 54 and sleeves 52 and 53 remains or tends to remain stationary. In this manner upward'movement of the body I Il and stem 48 causes the bull nut 5I to be moved upwardly against the lower end of the sleeve 53 and moves the latch 55 through the sleeve 53 so that the spring 58 pivots the latch outwardly to a position where its shoulder 51 opposes the upper end of the sleeve 53. After being raised, as just described, the tool is lowered or moved downwardly to actuate the cutter II. The cooperation of the latch shoulder 51 with the sleeve 53 connects the stern 48 with the assembly of the springs 54 and the sleeves 52 and 53 so that the springs engaging the interior of the casing C hold or tend to hold the stem 46 and wedge block 43 against downward movement. The spring assembly of the tail piece thus serves to resist downward movement of the wedge block 43 during the downward movement of the body III and cutter Il. The cutter II moving downwardly with the body has the rounded lower edge 34 of its blade 3| in engagement with the wedge block 43 and as the body moves downwardly relative to the wedge block 43 to the position illustrated in Fig. 4 of the drawings the cooperation of the wedge face 43 with the lower edge of the blade causes the cutter to be swung or pivoted on the surface 24 about the axis A. As the cutter I I has the concave surface 31 engaging the surface 24 and has the ends 4| of its keys cooperating with the concave surfaces 28, it is constrained to turn or pivot about.

the axis A as just described. This pivoting or swinging of the cutter II on the surface 24 about the axis A moves its blade outwardly so that its point or corner 35 engages or penetrates the wall of the casing C. In practice, downward shifting of the body III relative to the wedge block 43 to the position illustrated in Fig. 4 of the drawings pivots the cutter II outwardly a suilicient extent to cause the cutter to have rm engagement with or to penetrate the wall of the casing. Further downward movement of the body I with respect to the wedge block 43 is unnecessary as the engagement of the blade 3| with the casing C causes the cutter to be swung or pivoted outwardly as downward movement of the tool through the casing is continued. As the perforator moves downwardly through the casing the cutter' II is swung about the axis A on the convex surface 24 until its concave surface 38 comes into contact with the convex surface 25. During the pivoting of the cutter II about the axis A the ends 4| of the keys 33 slidably engage or clear the concave surfaces 28 of the flanges 22. Engagement of the concave surface or face 38 of the cutter with the convex surface 25 results in swinging of the cutter II about the point or axis B as the downward movement of the tool is continued. It will be apparent how the swinging of the cutter II about the axis B changes the angle of engagement or attack of the blade 3| with respect to the casing C and results in the maximum projection of the blade 3| so that its upper corner 35 and its lower outer corner 6I penetrate the wall of the casing. During movement or swinging of the cutter II about the point B the ends 4I of the keys 33 slidably engage or clear the concave faces 28 of the flanges 22. Fig. 4 of the drawings illustrates, in full lines, the cutter II in the course of moving over the surface 24 while swinging about the axis A. Fig. 8 shows the cutter moving over the surface 25 while swinging about the axis B. The flat face 39 of the cutter nally comes into engagement with the inner wall of the channel member I and the keys 33 assume a vertical position or a position in longitudinal alignment with the keyways 23. The tool is then suddenly freed to move' downwardly with respect to the cutter I I as the elongate channel receives the cutter which is held stationary through its contact with the casing C. The sudden relieving of resistance to downward movement of the tol as the cutter enters the channel member I5, informs the operator that the cutter has been fully actuated or projected. The tool-may then be raised to withdraw the cutter II from the perforation. It is clear how upward movement of the body Il) with respect to the cutter rst brings the surface 25 into contact with the surface 38 and then results in swinging of the cutter about the axis B and swinging of the cutter about the axis A so that the cutter again assumes its retracted position in the opening I4 of the body. Upward movement of the body also causes the wedge block 43 to assume its normal position in the lower end of the body opening I4 permitting the retraction of the cutter. The tool may then be withdrawn from the well or again actuated if desired. It is to be noted that the present invention provides a perforator in which the cutter is projected or actuated outwardly a very substantial distance and has very effective perforating angles with respect to the casing C during its projection. 'I'he sudden freeing of the tool for downward movement when the cutter assumes its fully actuated position effectively informs the operator of the complete actuation of the tool.

Fig. 8 of the drawings illustrates a form of the invention in which the cutter II is` further projected from the body after its actuation by cooperation with the surfaces 24 and 25. In this form of the invention the inner wall of the channel member I5 is inclined upwardly and outwardly from the surface 25. The flanges I6 of the channel member I5 are correspondingly inclined. The inner surfaces 1I of the flanges 22 are parallel with the outer surfaces of the ilanges I5 providing inclined keyways 23a. 'I'he other parts of the tool may be identical with those described above. After projection or actuation of the cutter II by cooperation with the surfaces 24 and 25, further downward movement of the body Il causes the inclined surfaces of the channel member I5 and the flanges 22 to continue the projection of the cutter. The extent of this projection of the cutter depends upon the inclination and length of the channel in which the shank of the cutter II operates.

Having described only typical preferred forms and applications of my invention, I do not wish to be limited or restricted to the specific forms and applications herein set forth, but' wish to reserve to myself any modifications or variations that may appear to those` skilled in the art or fall within the scope of the following claims:

Having described my invention, I claim:

1. A perforator including, a body, two projections on the body having convex surfaces, a cutter carried by the body to successively cooperate with the projections to progressively swing outwardly, and means for actuating the cutter to cooperate with one projection to swing into engagement with the casing, the cutter being caused to cooperate with the second projection by movement of the body relative to the casing.

2. A perforator including, a body, two projections on the body, a cutter carried by the body to successively cooperate with the projections to progressively swing outwardly to perforate the casing, and means `i'or actuating the cutter, the body having a longitudinal opening for passing the cutter after its cooperation with the second projection whereby the body may move longitudinally relative to the actuated cutter to inform the operator of the actuation of the cutter.

3. A perforator including 'a body having a surface curved about one axis and a second surface curved about an axis spaced longitudinally and outwardly from the first mentioned axis, a cutter movable on the surfaces from a retracted position in the body to a position projecting from the body to perforate the casing, and means for actuating the cutter.

4. A perforator including a body having two convex surfaces curved about points spaced longitudinally and transversely, a cutter movable from one surface to the other between a position in the body and a position projecting from the body, and means for actuating the cutter.

5. A perforator including a body having two projections presenting convex surfaces, a cutter operatableto ride over one surface and then over the other surface to progressively swing outwardly between a position in the bodyiand a position projecting from the body, and means for operating the cutter.

6. A perforator including a body having a longitudinal channel, projections on the wall of the channel presenting convex surfaces, a cutter normally disposed in the body adapted to move over said surfaces to progressively swing outwardly to assume a position projecting from the channel to perforate the casing, and means for causing such movement of the cutter, the channel being adapted to receive the inner portion of the cutter after its movement over the surfaces to permit movement of the body relative to the cutter.

7. A perforator including a body having a longitudinal channel, projections on the wall of the channel presenting convex surfaces curved about points spaced longitudinally and transversely of the body, a cutter adapted to move over said surfaces to swing about said points between a position in the channel and a position projecting from the channel to perforate the casing, there being a keyway in the wall of the channel, a key on the cutter movable in the keyway, and means for causing movement of the cutter over said surfaces.

8. A perforator including a body having a longitudinal channel, projections on the wall of the channel presenting convex surfaces, a cutter normally disposed in the body and adapted to successively move over said surfaces to progresin' the body to a position projecting from the body to perforate the casing, and means for actuating the cutter, said means including a wedge cooperating with the cutter.

10. A perforator including a body having projections presenting convex surfaces, a cutter successively movable over the surfaces to progressively advance from a retracted position in the body to a position projecting from the body to perforate the casing, and means for actuating the cutter, said means including a wedge for engaging the cutter, and a easing engaging tail piece controlling the wedge.

11. A perforator including a body having a surface curved about one axis and a second surface curved about an aids spaced longitudinally and outwardly from the tlrst mentioned axis, the second surface having a larger radius of curvature than the first mentioned surface, a cutter movable over the said surfaces to perforate the casing, and means for operating the cutter over the first mentioned surface, the cutter being movable-over the second surface by downward movement of the body.

12. A perforator including a body having a surface curved about one axis and a second surface curved about an axis spaced longitudinally from the first mentioned axis, one of said surfaces having a larger radius of curvature than the other., a cutter movable over the said surfaces to perforate the casing, means for actuating the cutter, and means for maintaining the cutter in cooperation with the surfaces during its actuation.

13. A perforator including a body having a longitudinal channel, projections on the wall of the channel presenting curved convex surfaces, a cutter adapted to successively move over said surfaces to progressively swing outwardly between a position in the channel and a position projecting from the channel to perforate the casing, and means for causing such movement of the cutter, the channel being adapted to receive the inner portion of the cutter after its movement over the surfaces and being inclined to cause further projection of the cutter from the body.

, 14. A casing perforator embodying the combination of, a body having an inclined slot provided with guide ways in its side walls, a cutter arranged in the slot and having a perforating blade, flanges on the cutter adapted for reception in said guide ways, said slot having a pocket below the guide ways normally containing the cutter in a retracted position where its flanges are out of alignment with the guideways, a cam surface on the body in the pocket cooperable with the cutter to effect swinging of the cutter about a relatively fixed axis to penetrate the casing and bring its flanges into alignment with the guide ways when the blade is engaging a casing, and means operable by initial longitudinal movement of the body for swinging the cutter to bring its blade into engagement with the casing and to condition it for said actuation by the cam surface.

15. In a. casing perforator the combination of,

a body having walls forming a guideway, the

guideway having an inclined wall, a' cutter in the body having a perioratlng blade, a relatively xed fulcrum in said guideway cooperable with the cutter during aninitial phase of downward movement of the body relative to the cutter to eect swinging of the cutter about said fulcrum to project its blade, and means on the cutter for engaging the said inclined wall of the guideway to arrest the swinging movement of the cutter and to effect transverse shifting of the cutter to a further extended position .during continued downward movement of said body.

16. A casing perforator comprising, a body havlng a slot, a cutter arranged in the body for free sliding movement in the slot, a blade on thev cutter adapted to be projected from the slot into engagement with a casing, a member normally supporting the cutter in a retracted position in the slot and operable to move the blade into biting engagement with the casing upon downward movement of the body, relatively fixed fulcrum means in the slot for rocking the cutter to cause its blade to perforate the casing upon an initial phase of the downward movement of thebody, and means in the lslot for holding the cutter against rocking movement and moving the cutter to a further extended position during. a subsequent phase of the downward movement of the body.

17. A casing perforator inc1uding,'a body having a slot, a cutter arranged in the body for free movement in the slot, a plurality of xed fulcrums in the slot cooperable with the cutter to effect successive swinging of the cutter from a retracted position to a4 projected position, and means operable to initiate such swinging of the cutter to project it into biting engagement with a casing.

18. A casing perforator embodying the combination of: an elongated body having an inclined T-slot'terminating at its lower inner end in a pocket; a cutter normally positionedin said pocket, said cutter having a shoe adapted toslide l in the T-portion of said slot and a blade adapted to be projected from said slot into engagement with a casing; and a cam surface in said pocket forming a fulcrum about which saidv cutter, when in compression, swings during a downward movement of said body whereby said shoe swings into alignment with the T-portion of said slot.

19. A casing perforator comprising: an elongated body having an inclined slot; a cutter mounted in said body for free sliding movement in said slot; a blade on said cutter adapted to be projected through said slot for perforating a casing; means comprising a fixed fuicrum in said slot for rocking said cutter during the initial downward movement of said body while said blade is in initial engagement with the casing; and additional means in said inclined slot for holding said cutter against rocking movement during a continued downward movement of said body.

20. In a casing perforator the combination of, a body having surfaces forming a guideway having an inclined wall, a cutter member in the body having a perforating blade, a body surface in the guideway forming a fixed fulcrum cooperable with the cutter member to swing the same and project its blade during an initial phase of downward movement of the body relative to the cutter member, and means on the cutter member cooperable with said inclined wall of the guideway to arrest the rocking movement of the cutter member and move the cutter member transversely of the body to an extended position during a continued downward movement of the body.

21. A perforator including, a body having walls forming a guideway and relatively xed fulcrums in the guideway, the fulcrums being longitudinally and transversely spaced one from the other, a cutter in the body movable from a retracted position to a position projecting from the body through cooperation with said fulcrums, and means for actuating the cutter.

22. A casing perforator comprising an elongated body having an inclined slot, a cutter mounted in said body for free sliding movement in said slot, a blade on said cutter adapted to be projected through said slot for perforating a casing, fixed fulcrum means in the bottom portion of said slot for rockingv said cutter during the initial downward movement of said body while said blade engages a casing, additional means for holding said cutter against rocking movement in said inclined slot during a continued downward movement of said body, and means for controlling said cutter whereby said blade is engaged with a casing to beperforated. v 23. A casing perforator comprising, an elongated body having an inclined slot, a cutter mounted in said body for free sliding movement in said slot, a blade on said cutter adapted to be projected through said slot for perforating a casing, xed fulcrum means in the bottom portion of said slot for rocking said cutter during the initial downward movement of said body while said blade engages` a casing, additional means for holding said cutter against rocking movement in said inclined slot during a continued downward movement of said body, and means for controlling said cutter to engage said blade with a casing to be perforated, said last mentioned means comprising a wedge member slidably mounted in said slot below said cutter, a mandrel attached to said wedge member and extending below said body, and friction means on said mandrel engaging the interior of said casing.

24. A casing perforator embodying, a slotted body, a cutter mounted in said body for free sliding movement in the slot therein, a blade on said cutter adapted 4to be projected from said slot into engagement with a. casing, means in said slot for normally supporting said cutter in a retracted position, means for swinging said blade from said slot into biting engagement with said casing comprising fixed fulcrum means in said slot for rocking said blade to perforate said casing during an initial downward movement of said body, and means Acomprising guideways in 'said slot and flanges on said cutter for reception in said .guideways for holding said blade* against rocking movement and at the same time moving the same transversely into an extended' position during a continued downward movement ofsaid body.

25. A casing perforator embodying, a slotted body, a cutter mounted in said body for free sliding movement in the slot therein, a blade'on said cutter adapted to be projected from said slot into engagement with a casing; means in said slot for normally supporting said cutter in a retracted position, xed fulcrum means adaptedl to engage the cutter and imparta plurality of independent swinging movements to said cutter thereby rocking said blade to perforate a plurality of casings during an initial downward' movement of said body, and means for holding said blade against further rocking movement and at the same time moving same transversely into an extended posirtion during a continued downward movement of said body.

26. A casing perforator embodying, a body having a slot therein, a cutter mounted in said body for tree sliding movement in said slot, means for normally supporting said cutter in a retracted position in said slot, means for swinging said cutter to extend same into biting engagement with said casing including a plurality of iixed fulcums in said slot for successively swinging said cutter from an inclined toward a horizontal position for perforating an engaged casing during an initial vdownward movement of said body, and means for holding said cutter against swinging movement and at the same time extending the same transversely from said body during a continued downward movement of the body.

27. A casing perforator embodying, a body having a slot therein, a cutter mounted in said body for sliding movement in said slot, a blade on said cutter, fixed fulcrum means in said slot for swinging said cutter from van inclined toward a horizontal position during an initial downward movement of said body while said blade is engaged with a casing whereby said casing is periorated, and means in said slot for holding said cutter against pivoting and at the same time forcing said blade from said body during a continued downward movement of said body.

28. A casing perforator comprising an elongated body having an inclined slot, a cutter mounted in said body for free sliding movement in said slot, 'a blade on said cutter adapted to be projected through said slot for perforating a casing, fixed fulcrum means in said slot for rocking said cutter during the initial downward movement of said body while said blade engages a casing, additional means for holding said cutter against rocking movement in said inclined slot during a continued downward movement of said body, and means for controlling said cutter whereby said blade may be engaged with a casing to be perforated, said last mentioned means comprising a wedge member slidably mounted in said slot below said cutter, a mandrel attached to said wedge member and extending below said body, friction means on said mandrel engaging the lnterior of said casing, and means on said mandrel for optionally locking said friction means against movement relative to said mandrel during a downward movement of said body.

ORA A. BROWN.

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