US2638801A

US2638801A - Casing perforator

Info

Publication number: US2638801A
Application number: US34184A
Authority: US
Inventors: Ralph J Klaasen; Eugene M Olsen
Original assignee: Individual
Current assignee: Individual
Priority date: 1948-06-21
Filing date: 1948-06-21
Publication date: 1953-05-19
Anticipated expiration: 1970-05-19

Description

May 19, 1953 R. J. KLAASEN E TAL CASING PERFoRAToR 4 sheds-sheet 1 Filed June 2l, 1948 BY fw May 19, 1953 R .L KLAASEN TAL CASING PERFORATOR 4 Sheets-Sheet 3 Filed June 21. 1948 INVENTORS.

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RALPH l f a f l l l l l l f l l l f r n l l l l r r l r f l l l r r r r r u l l r u l l l l r r f n l l I r a l l l l l l n l l l r l l l 5 l f r r l f n r f r l l a l l f a l l u u u 5 l l u r f l I u l l l l l l l l l l a 1 l l a l l l f g l r f r z f r g r r l r f g 4 #free/vga May 19, 1953 R. J. KLAASEN Erm. 2,638,801

cAsING PERFORATOR Filed June 2l. 1948 4 Sheets-Sheet 4 IN V EN TOR5.

59 BY la/fw #from/5,6.

Patented May 19, n1953 CASINr PERFoRA'roR Ralph J. Klaasen, Lompoc, and Eugene M. Olsen,`

` Avenal, Calif.

Application une 21, 1948, Serial No. 34,184

Claims. l

This invention relates to methods and apparatus for perforating pipes, casings and the hke which are set in the earth, soil or the like, and forming passageways in the earth or soil, which passageways extend outwardly from the pipes or casings.

It is the main object of this invention to providean apparatus which can be lowered into a pipe, casing or the like to a desired depth, the apparatus being so designed that it can be operated to perforate the pipe, casing or the like, the apparatus permitting fluid under high pressure to pass therethrough and to shoot out through the ports made in the pipes or casings and into the surrounding soil and earth and bore passageways out from the pipe or casing whereby oil or the like may seep or iloW into the passage- Ways and be collected and removed.

Prior appparatus for perforating casings, `pipe or the like, have been, to my knowledge, limited to apparatus for either merely punching or ripping the Well casing or perforating the well casing by means of explosives or the like but it is the Ipurpose of the present invention to provide an apparatus adapted for perforating pipe and to hydraulic out passageways which apparatus can` be used to provide much longer passageways than heretofore possible, it being obvious that the longer the passageways the more oil can seep or ilow into the passageways and therefore providing a more eiiicient method for removing oilfrom oil bearing sands and the like.

Another object of this invention is to provide a well perforator which is attachable to a drill string or the like, and adapted to be lowered into a well casing, the perforator comprising means supported from the drill string and supporting at least one boring drill, means movable with the first named means and disconnectible therefrom uponrotation of the drill string to set the rst named means upon subsequent lowering` of the drill string, and the perforator including means providing a driving connection between the` drill string and the drill after the first named means is set for rotating the drill, and the perforator is designed so that fluid under high pressure will be conveyed therethrough and forced or shot out through the ports formed in the casing preferably while the drills are still in the pipe or casing.

2 be raised to another level and to perforate the casing or pipe and to be used to hydraulic other passageways out into the surrounding earth, soil or sand- Another object of this invention `is to provide a method of forming passageways in the earth surrounding a pipe setin the earth consisting in drilling a plurality of -ports in a pipe at one level yand forcing iiuid under high pressure down into the pipe and out through the ports to penetrate the bore into the earth to form passageways extending outwardly from the pipe.

With the foregoing and other objects in view, which will be made `manifest in the following detailed description and specifically pointed out in the appended claims, reference is had to the accompanying drawings for an illustrative embodiment of the invention, wherein:

Fig. 1 shows a perforator embodying the present invention in a lowered condition in a pipe or casing;

Figs. 2a, 2b and 2-c show respectively enlarged upper center and lower sectional views of the apparatus disclosed in Fig. l;

Figs. 3a, 3b and 3c show respectively enlarged upper center and lower sectional views of the apparatus disclosed in Fig. 1 wherein the various parts of the apparatus are shown in different operating conditions; f p

Fig. 4 `is an enlarged partial view of Fig. 3c showing the parts of the apparatus in still a further stage of the operation `of the device;

Fig. 5 is an enlarged sectional view along lines 5-5 -of Fig. 2b;

Fig. 6 is an enlargedsectional View along lines 6-6 of Fig. 20;

Fig. 7 is an enlarged sectional view along lines 'l-'I` of Fig. 2c; and

Fig. 8 is an enlarged sectional view along lines 8-8 of Fig. 2c.

Referring to the accompanying drawings wherein similar reference characters designate similar parts throughout, 9 in-dicates a casing, pipe or the like which is set in the earth, soil or sand generally indicated by reference numeral III, andreferring to Fig. l and reading from top to bottom the perforator is attached to the end of a drill string or the like generally entitled I I, the perforator comprising an auxiliary body I2 preferably threaded onto lthe drill string as shown in Fig. 3a, an adapter collar I3, a weight floating sleeve I4, said adapter collar being threaded between the auxiliary` body and the Weight floating sleeve, as shown in Fig. 3a.

a splined drive collar I threaded to the weight iloating sleeve I4, as shown in Fig. 3b, a splined drive shaft I6, a setting tool guide collar I1 ywhich is threaded onto a setting tool body I8, see Fig. 3b, the setting tool body I8 having a setting tool generally indicated at I9 provided thereon, the setting tool body I8 being threaded onto theI main perforator body 2B,I see Fig. 3c.. and the main perforatorbody havingv a bottom bullnose 2| threaded thereon, as shown in Fig. 3e.

A fluid screen or filter 25 is provided in the upper end of auxiliary body I2, see Fig. 2a. The adapter collar I3 has a bore down through the center thereof and la mandrel 2,1 has. the upper. enlarged end thereof 28 supported by the upper portions of the adapter collar. The main body of the mandrel 21 passes down through the bore in adapter collar I3 down through the center of hollow weight floating sleeve I4 .through a bore in a retainer collar 30. down through a central bore in the splined drive shaft I6 and into the main perforator body 20. this description being best followed by viewing Figs. 2a, 2b and 2c in sequence.

A rubber packer 32 encloses 4the body of the mandrel just below the upper end 23 thereof and this rubber packer 32 is set within an annular groove provided in adapter col-lar I3'. The retainer collar 3D is preferably threaded on the upper end of splined drive shaft I'B and' sup ports the drive shaft from the splined drive collar I5. An upper compression spring 34, compare Figs. 2a, 2b, is positioned between the adapter collar I3 and the retainer collar 30 and always urges the splined drive shaft in its lowerniostv position.

A lower compression spring 35, is positioned around splined drive shaft le and between splined drive collar I5V and setting tool guide collar I1 and rests on friction washers 31.A This lower` compression spring 3-5 always urges the main perforator body 20 away from the upper portion of the perforator.

The splined drive shaft I6' has a rubber packer 3S positioned in an annular groove provided therein, saidrubber packer enclosing the main body of the mandrel 21, see Fig. 2c.l

There is a driving connection provided between the splined drive shaft I'G and' the main perforator body 20 and comprises a gear clutch system. As can be seen by comparing Figs. 2c and 6, splined drive shaft I6 has no means of driving the sett-ing tool body I'B, and so. the only driving connection between the spline@ drive shaft I6 and the main perforator body 211, is through the gear clutch system which comprises a driving member 4,0 which is threaded and pinned to splined drive shaft f6 and has. upper and lower annular clutch teeth 4I and 42 respectively, the upper clutch teeth 4I` meshing with clutch teeth 43, which are provided on setting tool body I8, when the splined drive shaft Il is in its uppermost position. When the main perforator body 20 isset in ythe well" in the manner to .be described, and the drill string H lowered, the splined drive shaft Hwith its driving member lil will move from the position shown in Fig, 2.o to the position shown in Fig. 3c where the lower annular clutch teeth 42 on driving' member 40 will engage annu-lar clutch `teeth 46 provided on a maindrive collar 41, said main drive collar resting on a friction washer which in turn rests on an annular ledge provided by the main perorator body.

ln its upper position the driving member 40 can drive 'the main perforator body 20 but is unable to drive the main drive collar 41, and driving member 4B in its lower position is able to drive main drive collar 41 but is unable vto drive the main perforator body 20.

The lower part of main drive collar 41 has a main drive beveled gear 50, see Fig. 4, which is secured to main drive collar 41 by any suitable means there being a friction washer 5l between the ybeveled gear 5@ and the ledge on the main perforator body 20. Main beveled gear 5B meshes with three beveled gears 54 which beveled gears are rotatably mounted in gear supports 56 which may be formed integral with or attached to a base, ring 51 which is permanently fastened by any suitable means to the main perforator body 20:, as shown best. in Fig. 4.

The outer ends of the hubs of gears 54 are supported by retainer plugs 59 which are preferably threaded into the main perforator body 20. Clearance washers til are preferablyprovided to space the beveled gears 54 from `the retainer plugs 59.. Drill shafts 63 are slidably housed within gears 54 and keyed thereto Iby keying means 64 so that when beveled gears 54 are rotated the drill shafts t3 with the drill heads 65 on the ends thereof will be rotated. Dr-ill shafts G3 preferably have knobs- 6'1 formed integrallyY or attached to the inner ends thereof to serve as retainers to prevent the drillshaft from moving out of the main perforator body 28. Compression spr-ings 10- are provided about the drill shafts 63 and positioned between the knobs B1 and supports 56 and always urge the drill shafts 63 into their innermost position in the main perforator body 2-9. The drill shafts 63 have hollow bores through the center thereof, as can best be seen in Fig. 8, for purposes to be described.

The mandrel body 21' has an end .taper member 12 preferably threaded therein and. this mandrel drive end taper is tapered, as shown in Fig. 4, and has a reduced endthereon which reduced end rests between the three drill shafts 63 when the mandrel is in` its uppermost position. When the mandrel 2f# isl lowered downinto the main vperf'orator 20 the tapered surfaces on end taper member 12' will bear against the knobs B1" on drillsv 63 and force the drills in an outward direction under the influence of the weight of the mandrel 21. There is a mandrel stop ring 14 securedwithin the bottom bullnose 2I and serves to prevent the end taper member from contacting the bottom of the bottoni bull-nose 2 l', as can be seen in Fig. 4.

The setting tool generally indicated at I=9 comprises a ring 11 which has an open slot 18 engaging a pin 153, Ias best seen by comparing Figs. l and 3b, and the ringv 11 has upwardly extending belly springs Sil which are so bent as to fricti-onally engage the side wal-1s of the pipe or casing 8, see Fig. 3b. Slips 852 are pivotally connected to shank members 8'3 which in turn are pivoted to the ring 11' and these slips 82- and Shanks 83 will be in the position. shown in Fig. 2b when the perforator is in its fully extended plosition. The setting tool body t8 is provided with tapered" su-rfaces, as shown in Fig. 312, S0 that when the setting tool is disconnected from the setting tool body that the slips 82 will be wedged between the tapered surfaces on setting tool body I8 and thecasing 9'.

The perforator is so construct-edv and arranged that fluid under high pressure can pass therethrough -andthe fluid passes down through screen or filter 25 through a hollow bore in mandrel 21 and out through ports 85 down between the mandrel 21 and the splined drive shaft, see Fig. 4, down between the mandrel and the member 41 and then out through the bores provided in drill shafts 63, see Fig. 8, and out through the ports which will be provided in the casing or pipe 9.

Figs. 2a, 2b and 2c show the perforator in sectional view in its extended position and in this View it can be seen that the ports 85 are above the lower rubber packer 3H so that the fluid is effectively trapped within the upper part of the perforator. However, when the drills 63 have drilled through the casing 9 and the mandrel 21 is in the position shown in Fig. 4, the ports 85 have moved down below the rubber packer 38 and therefore uid under pressure can fiow down through the mandrel out through the ports 85 down along the mandrel and out through the hollow drills 63 penetrating the surrounding soil, sand or the like and hydraulicing or boring a long passageway outwardly from the perforator into the sand, soil or the like.

The operation of the perforator of the present invention is as follows. The perforator is attached to the drill string II and lowered in its fully extended position down in a well casing or pipe 9 with the belly springs 80 frictionally 0 engaging the inner surfaces of the casing or pipe 9. The compression springs 34 and 35 are designed to be strong enough so as to hold the perforator in its` fully extended position even with any maximum frictional engagement between belly springs 8i! and are also designed so that the parts of the perforator may rub against the sides of the casing S without the perforator being compressed. Therefore, the mandrel 21 is kept in its upper position, as depicted in Figs. 2a, b and c, and is not able to force the drill 63 out from the perforator, thereby protecting the drills from being damaged in the downward movement of the perforator. The perforator may be used to either explore different -levels in the oil well casing to determine if oil bearing sands or the like are present or it may have been predetermined that these oil bearing sands were present but were passed up during the drilling of the well with the intention of later returning to recover the oil in these sands, soil or the like but in any event the operation and use of the device is substantially the same.

The perforator is lowered down in the well casing 9 to the lowest level at which it is desired to perforate the casing, during this time the belly springs 80 frictionally engaging the sides of the casing SJ. When the desired level is reached, the drill string II is rotated, with reference to Fig. l, in the direction such that the pin 19 moves around in the slot 18 and the operator may wish to move the pin into the open end of the slot or he may wish to cam up the setting tool which he may do by rotating the drill string a little farther. During this time the belly springs 80 prevent the setting tool from rotating and the operator then lowers the drill string so that the perforator moves downwardly with respect the disconnected setting tool so that the slips 32 are wedged between tapered surfaces on setting tool body I8 and the casing 9 and serve to set the lower portion of thev perforator, comprising the setting tool body I8, main perforator body 20 and bottom bullnose 2|. The driving connection which en# ables the setting tool body I8 to be revolved with respect the setting tool I9 comprises the driving member 40 on the lower end of.splined shaft I6, its upward facing annular clutch teeth 4I and the downwardly facing annular clutch teeth 43 provided on setting tool body |31. Upon further lowering of the drill string II the lower portion of `the perforator remains `stationary while the upper portion descends with the splined drive shaft IG sliding down within the main perforator body 2li, disconnecting the drive between the clutch teeth 4I and 43 and moving the drive member 40 to the position shown in Fig. 3c where the lower clutch teeth 42 engage the upper clutch teeth 46 on the driving collar 41 so that a driving connection is established between the drill string II and the drills 63. As soon as the clutch teeth 42 engage the clutch teeth 45 the spring 34 will begin to be compressed and it is preferred that these

springs

34 and 35 be compressed to an extent such that the mandrel 21 can move down and be stopped by the stop ring 14, the compressed spring 34 serving to keep the

clutch teeth

42 and 46 into engagement during rotation of the drill string I I. During this downward movement of the drill string II, the mandrel 21 moves from the position shown in Fig. 2c to the position shown in Fig. 3c forcing the drills 63 partially out of the perforator and into engagement with the casing 9.

The operator then begins toirotate drill string I I which rotation is transmitted by splined drive shaft I6 through clutch teeth42 and 46 down through beveled gears 55 and 54 to the slidably mounted drills 63 and since the full weight of the mandrel 21 bears down on the drill 63 the tapered portion of the end member of the mandrel applies force to the drills so that ports are provided in the casing 9. When the drills have fully penetrated thecasing 9 and moved to the position shown in Fig. 4, the mandrel 21 drops down to the position shown in Fig. fl and the ports in mandrel 21 pass rubber packer 38 so that the iiuidwhich is under high pressure in mandrel 21 now rushes down through the main perforator body 2li and out through the ports just formed by the drill 63 and since this fluid is under very high pressure it will shoot out with such force as to penetrate and bore long passages extending outwardly from the perforator and this period of fluid. boring or hydraulicing can continue for a predetermined period of time.

After the predetermined period of hydraulicing is completed, the drill string I I is then slowly raised during which time the mandrel 21 is raised until the smaller pointed end of the mandrel is between the drill knobs E1, during this time the spring 10 serving to retract the gears 63 within the perforator. During this raising of the drill string` II, the` springs 34 and 35 also aid in returning the perforator to its fully extended position. When the operator feels the resistance of the slips 82, which will occur when retainer collar 3B contacts splined drive collar I5 and clutch teeth 4i and 43 engage, the operator can then raise the drill string a predetermined distance to just above the next level at which ports are to be provided in casing 9 and then lower the drill string II to again set the slips 82 and the operation may be repeated. It will be understood, of course, that once the setting tool I9 is disconnected from the setting tool body I8 that it will remain disconnected during the succeeding drilling operations on the different levels and so that the slips e2 are automatically set by merely raising the drill string l! and lowering it slightly.

The operator is allowed a great deal of freedom in operating the device since he need not worry about the full weight of the drill string bearing on the driving connection between the

clutch teeth

42 and 46 since the only pressure on these teeth is supplied by the compressed spring 34.

A great advantage of the perforator of the present invention is the fact that the perforator can be lowered into a pipe or well casing and ports drilled into the casing, and fluid under high pressure passed down through the drill string through the perforator and out through the drill while the drills are within the ports and passages provided in the soil while maintaining the drill string at the initial drilling level; and the drill string may be thereafter raised to drill ports at another level and passages hydrauliced in the soil or sand out from the periorator while maintaining the perforator at this next level so that two operations, the drilling of the parts and the hydraulicing of the passages in the soil or sand, are accomplished consecutively while maintaining the perforator in one position.

IThe operator can determine when the drills l I have penetrated the casing e by watching the pressure of the fluid being pumped into the well and when the fluid pressure drops, which will occur when the ports 85 in mandrel 2l move down below rubber packer fill, the operator will know that the drills have passed through casing 9 and that the mandrel 2l is in its lowest position and therefore the period of hydraulicing out passagen ways can begin.

Various changes ina-y be made in the details of construction without departing from the spirit and scope of the invention as defined by the appended claims.

We claim:

1. A casing perforator comprising a body adapted to be lowered into a well casing by a runin string of pipe, ineans for setting the body into the casing so 'that the run-in string oi pipe 'may be rotated relatively thereto, one or .more drills mounted on said body for rotation and projecting movement relatively thereto, means providing a driving connection between the run-in string of pipe and the drill so that upon rotation of the run-in string relatively to the body the drills may be rotated thereby, means operable by the runin string for urging the drills outwardly, said drills being hollow, and means providing a cornrnunicating passage between the rundn string of pipe and the interiors of said drills whereby circulation fluid may be discharged through the drills.

2. A casing perforator comprising a body adapted to be lowered into a well casing by a run-in string of pipe, means for setting the body into the casing so that the run-in string of pipe may be rotated relatively thereto, one or more drills mounted on said body for rotation and projecting movement relatively thereto, means providing a driving connection between the runin string of pipe and the drill or drills so that upon rotation of the run-in string relatively to the body the drills may be rotated thereby, means operable by the run-in string for urging the drills outwardly, said drills being hollow, and means providing a communicating passage betweenl the (Mv run-in string of pipe and the interiors of said drills openable only after the drills have moved outwardly their maximum movements whereby circulation fluid may be discharged through the drills.

3. A casing periorator comprising a body adapted to be lowered into a well casing by a run-in string of pipe, slips on the body for setting the body in the casing, means providing a releasable connection between 'the run-in string and the body by which the body may be manipulated t0 set the slips and the run-in string thereafter rotated relatively to the body, casing drilling means on the body, and means providing a driving connection between the run-in string and the drilling means by which the drilling means may be operated by the run-in string upon rotating the run-in string relatively to said body.

4. A casing perforator comprising a body adapted to be lowered into a well casing by a run-in string of pipe, slips on the body for setting the body in the casing, means providing a releasable connection between the run-in string and the body by which 'the body be manipulated to set the slips and the run-in string thereafter rotated relatively to the body, casing drilling means on the body, means providing a driving connection between the run-in string and the drilling means by which the drilling ineens may be operated by the run-in string upon rotating the rundn string relatively to said body, said drilling means being hollow, and means for discharging circulation fluid from the run-in string through the drilling means.

5. A casing perforator comprising a body adapted to be lowered into a well by a run-in string of pipe, means for setting the body in a casing, drills mounted for rotation on the body and for projecting movement relatively thereto, a shaft having a splined connection with the run-in string of pipe adapted to be rotated thereby, means providing a driving connection between the splined shaft and the drills whereby the drills may be rotated by the run-in string when the n run-in string is rotated relatively to th-e body,

and a tapered mandrel suspended within the splined shaft adapted to be lowered thereby into engagement with the inner ends of the drills to urge the drills outwardly as they are rotated.

(i. A easing perforator comprising a body adaptedr to be lowered into a casing by a run-in string of pipe, means for holding the body against rotation relatively to the casing, a splined shaft having a splined connection with the run-in string of pipe, a crown gear rotatable in the body, a clutch providing a releasable connection be'- tween the splined shaft and the crown gear, pinions rotatably mounted within the body meshing with the crown gear, drills slidably keyed through the pinions adapted to be rotated thereby when the splined shaft is rotated by the run-in string of pipe, said splined shaft being' hollow, and a tapered mandrel slidable through the splined shaft adapted to be lowered thereby into engagement with the inner ends of thev drills so to urge the drills outwardly, and spring means urging the drills into their innermost positions,

'.7. easing Iuerforator comprising a body adapted to be lowered into a casing by a run-in strinv of pipe, moans for holding the body against rotation relatively to the casing, a splined shaft having a splined connection with the run-in string pipe, a crown gear rotatable in the body, a. clutch providing releasable connection between the splined shaft and the crown gear, pinions rotatably mounted within the body meshing with the crown gear, drills slidably keyed through the pinions adapted to be rotated thereby when the splined shaft is rotated b'y the run-in string of pipe, said splined shaft being hollow, and a tapered mandrel slidable through the splined shaft adapted to be lowered thereby into engagement with the inner ends of the drills so as to urge the drills outwardly, and spring means urging the drills into their innermost positions, said mandrel having a head thereon engageable with the splined shaft so as to be capable of being lifted thereby to allow the drills to be returned to their innermost positions by the spring means.

8. A casing perforator comprising a body adapted to be lowered into a well casing, means for holding the body against rotation relatively to the well casing, a splined shaft, means forming a splined connection between the splined shaft and a run-in string of pipe, a clutch element on the lower end of the splined shaft, a crown gear rotatably mounted within the body having a clutch element engageable by the clutch element on the splined shaft, pinions meshing with the crown gear and rotatably mounted on the body, drills slidably keyed in the pinions, spring means urging the drills into their innermost positions, and a tapered mandrel slidable in the splined shaft adapted to be lowered thereby into engagement with the drills to project the drills outwardly.

9. A casing perforator comprising a body adapted to be lowered into a well casing, means for holding the body against rotation relatively to the well casing, a splined shaft, means forming a splined connection between the splined shaft and a run-in string of pipe, a clutch element on the lower end of the splined shaft, a crown gear rotatably mounted within the body having a clutch element engageable by the clutch element on the splined shaft, pinions meshing with the crown gear and rotatably mounted on the body, drills slidably keyed in the pinions, spring means urging the drills into their innermost positions, a tapered mandrel slidable in the splined shaft adapted to be lowered thereby into engagement with the drills to project the drills ouwardly, said mandrel being hollow and having lateral ports thereon normally disposed opposite the interior of the splined shaft, a seal between the interior of the splined shaft and the tapered mandrel below the normal position of the ports, said ports being adapted to be exposed when the mandrel has descended to fully expand the drills to permit circulation fluid to be discharged therefrom, said drills being hollow, and means providing a -passage for the passage of circulation fluid from said ports to the inner ends of the drills so that circulation uid may be discharged therethrough.

10.y A casing perforator comprising a body adapted to be lowered into a well casing, means for holding the body against rotation relatively to the well casing, a splined shaft, means forming a splined connection between the splined shaft and a run-in string of pipe, a clutch element on the lower end of the splined shaft, a crown gear rotatably mounted within the body having a clutch element engageable by the clutch element on the splined shaft, pinions meshing with the crown gear and rotatably mounted on the body, drills slidably keyed in the pinions, spring means urging the drills into their innermost positions,

a tapered mandrel slidable in the splined shaft adapted to be lowered thereby into engagement with the drills to project the drills outwardly, said mandrel being hollow and having lateral ports thereon normally disposed opposite the interior of the splined shaft, a seal between thhe interior of the splined shaft and the tapered mandrel below the normal position of the ports, said ports being adapted to be exposed when the mandrel has descended to fully expand the drills to permit circulation iiuid to be discharged therefrom, said drills being hollow, means providing a passage for the passage of circulation iuid from said ports to the inner ends of the drills so that circulation fluid may be discharged therethrough, and means limiting downward movement of the mandrel with relation to the splined shaft whereby the mandrel may be lifted by the splined shaft to enable the drills to be returned to their innermost positions.

RALPH J. KLAASEN. EUGENE M. OLSEN.

References Cited in the le of this patent UNTED STATES PATENTS Number Name Date 1,127,011 Kafader Feb, 2, 1915 1,322,399 Baumann et al. Nov. 18, 1919 1,539,288 Cameron et al. May 26, 1925 1,693,013 Young et al. Nov. 27, 1928 1,998,804 Flury et al Apr. 23, 1935 2,033,562 Wells Mar. 10, 1936 2,066,409 Loring et al. June 5, 1937 2,120,615 King June 14, 1938 2,151,646 Subkow Mar'. 21, 1939 2,186,323 Brown Jan. 9, 1940 2,354,570 Benckenstein July 25, 1944 2,534,858 Ellis Dec. 10, 1950 FOREIGN PATENTS Number Country Date