US3018731A

US3018731A - Shear member for gas operated blasting cartridge

Info

Publication number: US3018731A
Application number: US256877A
Authority: US
Inventors: Jr Edward C Filstrup
Original assignee: Olin Corp
Current assignee: Olin Corp
Priority date: 1951-11-17
Filing date: 1951-11-17
Publication date: 1962-01-30
Anticipated expiration: 1979-01-30

Description

Jan. 30, 1962 E. c. FlLsTRUP, JR

SHEAR MEMBER FOR GAS OPERATED BLASTING CARTRIDGE 3 Sheets-Sheet 1 Filed NOV. 17, 1951 www@ INVEN TOR. @Me ci Hrs/@afk Nm. Q

Jan. 30, 1962 E. c. FILSTRUP, JR

SHEAR MEMBER FOR GAS OPERATED BLASTING CARTRIDGE 5 Sheets-Sheet 2 Filed Nov. 17, 1951 INVENTOR.

Jan. 30, 1962 E. c. FILSTRUP, JR 3,018,73

SHEAR MEMBER FOR GAS OPERATED BLSTING CARTRIDGE Filed NOV. 17, 1951 3 Sheets-Sheet 3 @if az 245g ZV fak/,42a C. fau-rea@ .Je

l INVENTOR.

BYZ 2 ljgl Patented jan. 3U, 1962 tice 3,618,731 SHEAR NEWER FOR GAS PERATED ELASTHNG CARTREGE Edward C. Fiistrnp, lr., St. `loseph, Mich., assignor, by

mesne assignments, to Olin Mathieson Chemical Corporation, Wilmington, Del., a corporation of Virginia Filed Nov. 17, 1951, Ser. No. 256,877 11 Claims. (Cl. lOl-25) This invention relates to improvements in blasting devices. More particularly, it relates to a device adapted to be inserted in a hole in the working face of a coal mine or in a mass of material to be broken, and is of the type charged with gas at extremely high pressures and having means for substantially instantaneously releasing the gas in a blast with a force sufficient to break down the coal or other material around the device. While these devices are used primarily in the mining of coal, it will be understood that their utility is not limited to the breaking of coal and that they may be used to break down gravel, and to separate granular material which may be frozen or otherwise adhered in a solid mass, and for any other purpose requiring a blast of great force.

The blasting devices may be charged with compressed air, being connected to an air compressor so that the charge of air under pressure is built up progressively until it reaches a value at which the device is to discharge for blasting the material to be broken. Alternatively, the invention may be applied in a blasting cartridge of the character adapted to be charged with an eXpansible gas and which contains a heating element or other means for rapidly expanding the gas and increasing the gas pressure until the blasting pressure is reached.

This invention relates to that class of blasting or material-breaking devices in which a shear member is used which is weaker than the remaining portion of the device. These devices have a strength calculated to withstand the pressure at which blasting occurs, and to permit the progressive increase of the gas pressure therein until it reaches the pressure at which the shear member will fail.

Devices of this character possess many advantages as compared with devices of this type in which the control of the blast is accomplished manually and independently of the pressure of the charge. Among these advantages is the fact that the force of each blast will be uniform if shear members of the same character are used for each shot. Also, devices of this character are less dangerous than devices lhaving manually controlled valves because the blasting pressure can be bled off gradually at the will of the operator without causing a blasting discharge.

Devices of the character using a shear member as heretofore developed, however, have been subject to various disadvantages. Among such disadvantages have een shearing or breaking of the control member only partially or in a manner which accommodated discharge only at a rate slow compared to the instantaneous discharge required to create a blast of maximum force and eifectiveness. Other disadvantages of prior devices are that they have required a time-consuming manipulation to remove the remnants of the fractured control or shear member and to replace the same with a new member after each blast, and which have been subject to the occurrence of leakagefresulting in a lack of eiiiciency, a high cost of operation, and a prolonging of the time required to develop within the cartridge the pressure required for blasting. A

It is the primary object of this invention to provide a device which will overcome these disadvantages, which will utilize a breakable member which will provide a discharge opening of large area upon breakage thereof, which will accommodate replacement of shear or control members rapidly and with only a slight manipulation, and which will seal the charge effectively to avoid leakage of gas from the device, and which can be manipulated manually;

A further object is to provide a device of this character which is simple in construction, which requires only a small number of parts, and which minimizes the need for parts that are machined to close or small tolerances or for parts having surfaces formed with high precision by time-consuming lapping, grinding or similar iinishing methods.

A further object is to provide a device of this character so constructed that annular resilient sealing members may be employed to seal joints between component parts.

A further object is to provide a device of this character which contains no parts which move during the operation of the device, except the pressure sheared part.

A further object of the invention is to provide a device of this character with a severable member clamped in a position to seal the charge containing chamber against leakage and so constructed that the clamping force exerted upon the severable member increases proportional to the increase in the pressure of the gas charge of the device.

A further object is to provide a device of this character having a severable or fracturable member which tits within a transverse passage in the device so that it may be installed and removed in a lateral direction upon release of the clamping action of two parts of the device and without requiring disassembly of those clamping parts, and wherein the severable member is readily accessible even though of a size not substantially greater than the transverse dimension of the blasting cartridge, so that the size of the hole which must be drilled in the Working face to receive the blasting cartridge is determined according to the transverse size of the cartridge and need not be enlarged because of the severable member.

A further object is to provide a device of this character wherein a severable member is clamped marginally intermediate the length of an elongated blasting cartridge to span the cavity of the cartridge and is so gripped and is formed of material of such ductility that it will shear instantaneously by an action simulating a punch action, with the result that a slug of a size and shape substantially conforming to the cross-sectional size and shape of the part of the cavity at which it is clamped is broken therefrom to permit an instantaneous substantially unrestricted discharge of gas under high pressure when said control member is sheared or fractured.

A further object of the invention is to provide a device of this character having a severable plate releasably mounted therein between the intake and the discharge openings thereof, wherein said discharge openings are spaced from one end wall of the device so that a slug severed or broken from said plate incident to discharge of the device is propelled against said end wall with a force suiiicient to crumple the slug and thereby avoid any diiiiculty in subsequent removal thereof from the cartridge.

Other objects will be apparent from the following specification.

In the drawings:

FIG. l is a side View of the device with parts shown in longitudinal or axial section.

FlG. 2 is a transverse sectional view taken on line 2-2 of FIG. 1.

FIG. 3 is a fragmentary side view of the embodiment of the invention illustrated in FIG. l.

FIG. 4 is a fragmentary longitudinal sectional view illustrating a modified embodiment of the invention.

FIG. 5 is a fragmentary longitudinal sectional View illustrating another embodiment of the invention.

FIG. 6 is an enlarged fragmentary detail sectional View illustrating a part of the embodiment shown in FIG. 5.

FIG. 7 is a perspective view of a part of the device illustrated in FIG. 5.

FIG. 8 is a transverse sectional View illustrating an alternative arrangement of the parts of the device shown in FIG. 7.

FIG. 9 is a longitudinal fragmentary sectional View of another modified embodiment of the invention.

FIG. l is a fragmentary longitudinal sectional view illustrating a slight modification of the embodiment sho-Wn in FIG. 4.

FIG. ll is a transverse sectional view taken on line 11-11 of FIG. 9.

Referring to FIGS. l to 3, inclusive, which illustrate one embodiment of the invention, the numeral designates an elongated tubular cartridge or container part having a strength and wall thickness adequate to sustain fluid pressures substantially in excess of the pressure of the blasting charge to be employed in the device. The body part 10 will have an apertured end wall (not shown) to which is connected a supply conduit 12 which communicates with a source of gas under pressuresuch as an air compressor. The supply conduit will communicate with the interior cavity of the cartridge part 10 so that a charge of gas under pressure maybe introduced intosaid cartridge. The opposite end of the tubular part 10 preferably includes a neck portion 14 having a reduced outer diameter with an exteriorly screwthreaded portion 16 extending for a part of the length of said neck and spaced from its ends. Between the screw-threaded portion 16 and the end of the neck 14 is formed an external circumferential groove 18.

A tubular sleeve or collar member 20 having an outer diameter or cross-sectional dimension substantially equal to the outer diameter or dimension of the part 10, and having an inner diameter of a size to permit it to' encircle the neck portion 14, has an internally screw-threaded part 22 engaging the screw threads 16 of the neck to anchor said collar 2t) to the neck 14. The collar 2) is of a length to project substantially beyond the end of the neck 14. The projecting portion of the collar 2t) has one or more lateral openings, hereV shown as a pair of diametrically opposed slots 24. Each opening 24 is of substantial length and width, the length thereof preferably being substantiallyrequal to the inner diameter of said collar, as best seen in FIG. 2. The collar 20 is provided with an inwardly projecting circumferential flange or shoulder 26 located adjacent to the wall of the opening 24 nearest to the threaded part 22 of said collar. The o-uter end portion of the collar, that is, the portion between the opening 24 and the outer end, is internally screw-threaded at 28.

A rigid annular member or clamping ring 30, sometimes referred to as a sleeve is received within the collar 20. The clamping ring 30 has an inner diameter substantially equal to the inner'diameter of the neck portion 14 and the tubular part 10 and abuts against the outer end surface of the neck 14. The rearV or 'innermost end portion of the ring 30 has an outer diameter substantially equal to the outer diameter of the adjacent end portion of the neck 14 and is interrupted by an outer circumferential groove 32. The ring 301has an intermediate portion whose outer dimension 34 is slightly less than the inner diameter of the inwardly projecting collar flange 26 to fit slidably and rotatably therein( The arrangement of the parts is substantially that illustrated outer end surface of the ring il is preferably dat and lies in a plane transverse of the axis of the ring 30. The length of the member 3) is such that, when its inner end surface bears against the end surface of the neck 14, its outer end surface will be located centrally of the openings 24 of the collar 2t).

An end cap or hollow discharge lead, having a tubular or cylindrical portion 4G with an outer diameter or dimension substantially equal to or conforming with the outer dimensions of the part 10 and the collar 20, is mounted by means of the collar 20 to complete the cartridge or container. The cap has an end wall 42 at one end and has a reduced neck portion 44 at its opposite end. The neck portion 44 is externally screwthreaded to engage the internal threads 22 on the outer ends of the collar 20. The end surface of the reduced neck portion 44 of the cap is flat or planar and perpendicular to the axis of the cap and is adapted to terminate centrally of the collar opening 24. The cap is made of steel or other metal of substantially the same strength and hardness as

parts

10, 20 and 30. The end portion 44 defines a shear ring, and its inner diameter is preferably substantially equal to the inner diameter of the ring 3i). A plurality of discharge passages 46 are formed in the wall 4t) of the cap, preferably spaced a substantial distance from the end wall 42 and adjacent to the neck 44, as illustrated.` The passages 46 extend in a general radial but inclined direction so as to extend at an angle to the `axis of the cap and to a plane transverse of the axis of the cap. The outer end of each passage is positioned rearwardly relative to the inner end of the passage, i.e., at a greater distance from the end Wall 42. The total cross-sectional area of all of the discharge passages 46 will preferably be substantially equal to the cross-sectional area of the bore of the

parts

30 and 44.

A plate or shear disc 50, preferably of rectangular shape as illustrated in FIG. 2, is clamped between the ring 30 and the shearing end of the neck 44 of the cap.

The plate 50 is of a size to accommodate continuous engagernent thereof with the end surfaces of the ring 30 and the neck portion 44 of the cap, and at the same time has at least a slight clearance with the opposite end walls of each of the slots 24. The plate will preferably be of slightly greater length than width so that the corner portions 51 thereof will project slightly beyond the outline of the collar 20 to facilitate grasping of such corner portions. In this connection Vthe Width o-f each slot 24, that is, its dimension parallel to the axis of the collar 20, will be such as to facilitate entry of the fingers of a user partly into the slot to facilitate gripping of such corner portions 51. The joints between the collar' 20 and the neck 14, an

I between the collar 2u and the annular member 30, yare in FIG. l, in which it will be seen that the spacing of the Y inwardly projecting `flange 26 from the end surface of the neck 14 is greater than the longitudinal dimension of Y the large grooved end of the ring 30 so that a limited axial movement of the ring 30 is accommodated. The outer end portion 36 of the ring 30 is of reduced thickness as defined by .a reduced outer diameter, and the' the area of the discharge.

sealed. For this purpose an annular resilient sealing member 52 is seated in Ithe circumferential groove V18 of the neck 14 of the body, and a similar annular resilient sealing member 54 seats'in the circumferential groove 32 of the annularmem-ber 30. These

seals

52, 54 are com.- monly known in the'iart as O-rings and are of the type which are formed of natural or synthetic rubber and are adapted torbe deformed under pressure so that the seal is improved as pressure increases. Y

For the purpose of cooling the portion o-f the device adjacent to the severable elo-sure plate 50, a conduitVl-S Vmay be connected with the line 12`to extend adjacent to the member 50 `as illustrated. The action of dischargingl air from the pipe serves to introduce a cooling action in It will be understood in this connection that if there are other points along the length of the body 1G at which a cooling action is desired, the same may be provided by locating apertures (not shown) in the conduit 13 to discharge a portion of the air through said apertures. It Will beiunderstood, of course, that the conduitsV 12 and 13, as hereY illustrated, are adapted only for use with devices operating by compressed air. ,Other means of supplying a gas may be provided as in the case where the device is to be charged by carbon dioxide or like gas and is further equipped with means for heating the gas to expand it rapidly and thereby develop the desired blasting pressure.

The operation of the device will be explained assuming that the invention is embodied in a compressed air cartridge. The body 10, lthe collar 20 and the ring 30 with the supply conduit 12 are assembled to constitute one part or unit of the device; the cap or

end member

40, 42 constitutes a second unit of the device; and the plate 50 is a part replaced after each operation of the device. Assuming that the cap is screw-threaded in the portion 23 of the collar 20 and that the device is to be conditioned for use, a plate 50 is slid through opening 24 into a space between the confronting ends of the clamping ring '30 and the shearing neck 44 of the cap until it assumes a position illustrated in FIG. 2 completely spanning the cavity or interior of the device. Thereupon, while the plate is held in this position, the

cap

40, 42 is rotated, as by manual manipulation and without the use of a wrench, to cause the plate 50 to be firmly clamped or gripped between the parts 30 `and 44. The device is then ready for use and, assuming that a hole has been drilled in the coal seam, the gravel bed or other material to be blasted, which hole is of a size to receive the cartridge, the cartridge will -be inserted into that hole with the cap end thereof foremost or innermost.

Compressed air or other gas under pressure is then fed into the cartridge through the conduit l2 until the charge reaches a pressure which will rupture or sever the plate S0. As the pressure increases within the cartridge during charging, the gas under pressure passes between the confronting end surfaces of the neck 14 and the clamping member 30. However, the gas is prevented from leaking to atmosphere by the annular

resilient sealing members

52 and 54. This pressure exerted on the end of the clamping member 30 is effective, however, to urge said clamping member longitudinally to increase the clamping pressure acting against the plate 50. Thus, as the pressure of lthe gas charge Within the container increases progressively, the clamping force exerted upon the plate 50 increases proportionately. The progressive inlcrease of the gripping force increases the tightness of the abutment of the outer end of the clamping ring 30 with the plate 50, thereby increasing the electiveness of the seal between the parts 36 and 50 in a manner to prevent leakage between said parts and to atmosphere through openings 24.

The plate 50 is preferably formed of a mild steel having at least a measure of ductility and being both softer and weaker than the other parts of the device. As a result of the use of such material, the plate is deformed, bent or oiset at the central portion thereof as the charge o-f gas pressure in the device approaches the maximum pressure or force which the plate Si) can withstand. As this deforming action occurs, the grip of the

parts

30 and 44 upon the margin of the plate 50 maintains that margin against inward slipping or movement, with the result that the central portion of the plate which is being deformed is stretched and reduced in thickness. The stretching occurs principally and continuously at the annular portion defining the margin of the central portion of the plate which is offset or deformed by the pressure. This deforming action continues until said annular portion of the plate has been stretched and weakened to such an extent that it suddenly severs. This severing is characterized by an instantaneous and continuous breaking or severing thereof from its gripped margin at the weakened annular portion outlining the deformed central portion of the plate and dened by the size and shape of the shearing neck 44. Thus the deformed central portion is separated from the plate as a slug comparable to the slug produced in a metal punching operation. The severing of this slug from the plate releases it and the escaping gas charge propels it at high velocity against the end wall 42 of the capi. The cap preferably is of such a length that the space between the plate 50 and the end 42 of the cap provides a suicient distance of travel to permit the severed slug to attain a high velocity under the propulsion of the high pressure, high velocity discharge of gas from the body 10. The velocity of the ejected slug is so high that, when it strikes the end wall 42, it crumples or folds incident to the impact, so that its overall size is reduced and it will not bind itself within the end cap but is freely movable therein.

The severing of the entire central portion of the plate 50 produces a discharge opening which is substantially unrestricted and which permits a discharge of the gas charge substantially instantaneously into the cap 40 and through the outlet passages 46. Such an instantaneous discharge is of great advantage since the force of the blast and the eiiiciency of the blast is inversely proportional to the time required to evacuate the gas charge. The blasting efficiency of this device is high compared to all previous forms of devices, with the 'result that the cubic capacity of the cartridge may be reduced compared to the cubic capacity of conventional gas pressure blasting devices capable of accomplishing the equivalent materialbreaking work. This permits reduction in the diameter or transverse dimension of a cartridge for any given length, and thus reduces the `diameter of the hole which has to be drilled to receive the cartridge. Even a slight reduction in the size of a hole to be drilled is of great importance and effects a great saving of power and time in the drilling operation. Thus the present device effects economies in the drilling operation as well as economies in cost of manufacturing and economies in the time required to condition the device for service after each operation.

The time required to condition the device for reuse after each operation is very small. The end cap 40 is rst rotated sufciently to release the clamping action upon the residual marginal portion of the plate 50 remaining after the blast, so that it may be withdrawn through a slot 24. Thereupon, another plate is inserted through opening 24 into proper position, and the end cap is rotated to clamp the new plate in position. After the discharge of the cartridge, the clamping action upon the plate is reduced compared to the clamping action which existed immediately preceding the discharge. In other words, as the pressure within the cartridge reduces to katmosphere incident to the discharge of the device, the

component of the clamping force acting through the clamping ring 30 also reduces. Consequently, the

end cap

40, 42 may be rotated easily and without requiring the use of special tools to release the severed plate. This facilitates rapid replacement of the plate 50.

It will be noted that the device is simple in construction and is composed of only a few parts. Therefore, it possesses the advantage that points of potential failure and wear are much reduced compared to the more complicated prior constructions of the type employing valves. Another advantage is that the parts may be disassembled readily in the event of wear or failure. Thus, if the end surface of the clamping ring 30 should become nicked so that it will not provide an effective sealing engagement with a plate 50, that ring can be replaced quickly by removing the collar 20 from the neck 14, withdrawing the defective ring from said collar, inserting a new ring within the collar, and then reconnecting the collar 20 upon the body 10. Another advantage of the device is the fact that the shear plates 50, which constitute the means controlling the pressure at which the device will blast or discharge, are simple in construction, inexpensive, may be compactly stored, and do not require great care in handling.

Referring now to the embodiments of the invention which are illustrated in FIGS. 4 and 10, the same referamarsi ence numerals are used to identify the same parts as in the FIG. 1 embodiment to the extent that the parts are similar. In this construction the parts bear substantially the same cooperative relationship Yas those in FIG. 1, and the only substantial difference in construction as compared to FIG. 1 is in the construction of the collar 20 and the clamping ring 30. Observe in this construction that the ring 30 is of substantially uniform cross-sectional dimension throughout its length, except at the reduced end portion 36. It will be understood in this connection that a reduced end portion 36, while preferred, is not essential and that the entire cross-sectional configuration of the ring 30' may be rectangular, with the end of the member bearing against the platel 50 for its full thickness. Alternatively, as seen in FIG. 10, the ring 30 may be of substantially rectangular outline, but with the outer margin of the clamping edge of the clamping ring somewhat beveled or curved at 90. The internally projecting flange or collar of FIG. 1 is eliminated in the FIG. 4 and FIG. constructions, so that the internal shape or bore of the entire portion of the collar within which the ring 30 ts is cylindrical and is not interrupted by'any projection. The clamp ring 30 has a sliding t Within the bore of the collar 20, but is subject to the frictional engagement of its sealing ring 54 with the inner surface of the collar 20. The frictional resistance to movement afforded by the sealing ring 54 will be sufficient to normally hold the member 30 Within the collar 20 and juxtaposed to the end of the neck 14 at all times and even when the plate 50 is removed and the

end cap

40, 42 is disconnected from the sleeve.

The embodiment of the invention illustrated in FIGS. 4 and 10 possesses all of the advantages and operating characteristics described above with respect to the FIG. 1 embodiment.

Another embodiment of the invention is illustrated inV FIGS..5, 6 and 7, wherein parts similar to those shown in other embodiments bear the same reference numerals. In this construction the cartridge body 10 and the gas supply conduit 12 are the same asillustrated in FIG. 1,

The clamping ring 60 in this construction is slightly different from the clamping rings of the other embodiments and is of the substantially rectangular cross-sectional shape best illustrated in FIG. 6. A circumferential groove 62 is formed in the outer periphery of the ring 60 spaced from but adjacent to the end surface of the ring which confronts the end surface of the neck 14. The opposite end surface 64 of the clamping ring 60 which confronts and abuts the severable plate 50 has an annular groove 66 formed therein which is preferably concentric withV the ring 60. This groove communicates with a plurality V4:0 and the collar 20 is the same as illustrated in FIG. 4. l

of vent passages 68 whose inner ends open at the inner Y periphery ofthe clamping ring and whose outer ends open at the groove 66 adjacent to the base or inner part thereof. An annular resilient sealing member '70, or O-ring, seats in the groove 66 for engagement with plate S0. Y

This construction substitutes the annular resilient sealing member foi-,the plain metal-to-metal seal of 'the embodiments shown in FIGS. l, 4 and 10. 'Ihis annular sealing member has the advantage that it is flexible and resilient so that it will respond to fluid pressure to assume a shape in conformity with the surface contour of the plate 50. Consequently, if any irregularitiesrexist in the surface of the plate 50, these irregularities will not subject the device to danger of leakage. Therefore, plates 50 may be used which do not have accurately finished flat opposed surfaces. The vent members 68 prevent the entrapment of uid under pressure behind the seal so that there is no danger that the sealing member 70 will be displaced from or forced out of'its seat when the end cap is loosened to remove the residual marginal plate portion after each discharge.Y The construction possesses the same portion to the pressure in the cartridge chamber, which was explained above with reference to the embodiment of FIG. 1.

The embodiment shown in FIGS. 5 to 7 differs from the embodiment disclosed in FIGS. l, 4 and 10 in another particular, namely, With regard to the apertures within the end cap. As here illustrated, this form of cap may include one o1' more large apertures 72 formed in the cylindrical wall 40 thereof and of a size closely approaching the cross-sectional size of the bore or cavity of the cap. This passage 72 will preferably be defined by end surfaces 74 which are inclined outwardly and rearwardly -to deflect the charge in an outward rearward direction therethrough upon discharge of the device. The device will preferably have a balanced relation of the parts, i.e., will include at least two opposed large dimension ports 72. Also, if desired, a plurality of smaller ports 76 may be provided in the cap similar to the ports 46 of the FIG. 1 embodiment and preferably located spaced from the end wall l42 of the cap. Y The end Wall `42 has a substantially conical inner surface similar to that shown in FIG. 1 to assist in bending, folding or crumpling of the central slug portion of the plate 50 which is hurled thereagainst with great force. This construction of cap possesses substantially the same advan tages as that of FIG. 1 although at some sacrifice of the extent of control of direction of discharge of the gas as compared to the FIG. 1 embodiment due to the large size of the ports 72. lIn other words, the control of gas discharge in a rearward outward direction from the cap is somewhat lessened. This is not important and does not interfere with the functioning of the device, however,

because the end wall 42 of the device is imperforate so that substantially the full pressure of the gaseous charge is directed against the end wall upon discharge, and holds the cartridge within the drill hole. The device possesses one advantage compared to the FIG.` 1 embodiment, in that the size ofthe opening or openings 72 is large enough to accommodate passage of the crumpled metal slug therethrough so that the slug can be removed easily after each operation. This is contrasted with the arrangement in FIG. 1 where complete removal of lthe cap is required to remove the slug, and the cap must be so removed to remove the retained slugs after a series of operations of the device. Usually it will be necessary to completely remove the cap of the FIG. 1 device after live or six shots,

and this consumes time which is not required in the use of the FIG. 5 embodiment. v

The use of apertures 72 and '76 of different sizes is not necessary. Thus, as illustrated in FIG. 8, the cap may be provided with a plurality of apertures 78 of uniform size arranged in its cylindrical Wall portion 40 in substantially equally spaced relation. These apertures 7S will be of a size large enough to permit passage therethrough of the crumpled metal slug produced by the blast, and may be so located that the operator may reach through one opening with his lingers to direct a crumpledV slug to and through another outlet opening, in the event a crumpled slug does not fall freely from the cap through an aperture 78.

Another embodiment of the invention is illustrated in FIG. 9. In this embodiment the use of a separate clamping member is avoided. The reduced neck portion 14 of the cartridge part 10 is elongated compared to the form of the neck in FIG. 1, to provide a tubular portion 80 of substantial length projecting longitudinally outwardly beyond the screw-threaded portion 16 of( said neck. An annular groove 82 is formed in the outer end surfaceV of the portion 80 substantially concentric therewith. A plurality of vent passages 84 are formed in Vthe neck 80, being open at the interior surface of the neck and communicating with the groove 82 adjacent its bottom. AnV

annular resilient sealing member 86 is seated in the groove 82 and has sealing engagement with the severable control plate 50. The collar 20 in this embodiment is of subaolsfrsi stantially the same construction as illustrated in FIG. 4. The end cap is substantially of the same construction as illustrated in FIG. 1, but here is shown as being of shorter length than the cap shown in FIG. l. One or more circumferentially elongated discharge openings 92, inclined rearwardly and outwardly, are located adjacent to the end wall `45t of the cap.

This device operates in substantially the same manner as the devices described previously. However, the clamping pressure exerted upon the plate 50 remains substantially uniform instead of increasing progressively as the gaseous charge increases, as in the other embodiments. The seal provided by the use of the annular resilient sealing member 86 is effective at all pressures, however, despite the uniformity of clamp action. The number of parts required in the device is reduced by the elimination of an individual clamping ring of the other embodiments, and also by the elimination of the two annular

circumferential seals

52 and 54 of FIG. 1 required with the separate annular clamping ring.

The shortened longitudinal dimension of the end cap is feasible in this construction because the shape and location of the apertures 92 permits ejection of the severed plate slugs automatically. The circumferential size of the apertures 92 approaches the size of the inner diameter of the shear ring portion 44 of the cap, and the dimension of the apertures longitudinally of the cap is substantially wider than the thickness of the severed slug of plate 50 even when the latter is crumpled. Also, the apertures 92 constitute the only discharge outlets existing in the cap. Consequently, upon failure of the plate 50 and formation of the slug, the slug is ejected by the air and strikes the end wall 42. The air stream likewise strikes the end wall and is deected laterally thereby to exhaust at outlets 92. The slug is carried with the deflected air stream and is ejected from the cap. The openings 92 are sufficiently large to permit insertion of a tool to probe for and remove any slug which remains in the cap. Observe also that the inclination of the discharge openings causes gas discharge in a direction to prevent the device from flying out of the drill hole.

While I have illustrated herein various embodiments and forms which my invention may take, it will be. understood that further changes in construction may be made within the scope of the appended claims without departing from the spirit of the invention.

I claim:

l. A blasting device comprising a container open at one end, a cap having lateral discharge openings, a collar encircling and projecting longitudinally from the open end of said container, said collar having a lateral opening intermediate its ends and having an interiorly threaded portion threadedly receiving said cap, and a rupturable plate slidable in said collar opening and clamped between said container and cap in alignment with said collar opening.

2. A blasting device comprising a container open at one end, a cap having lateral discharge openings, a collar encircling and projecting logitudinally from the open end of said container, said collar having a lateral opening intermediate its ends and having an interiorly threaded portion threadedly receiving said cap, a rupturable plate slidable in said collar opening and clamped between said container and cap, and an annular resilient sealing member sealing the joint between said plate and said container.

3. A blasting device comprising a container open at one end, a cap having lateral discharge openings, a collar encircling and projecting longitudinally from the open end of said container, said collar having a lateral opening intermediate its ends and having an interiorly threaded portion threadedly receiving said cap, a rupturable plate slidable in said collar opening and clamped between said container and cap, the end surface of said container having an annular groove, and a resilient annular sealing member seated in said groove and engaging said plate.

4. A blasting device comprising a two-part cartridge, one of said parts being adapted to contain gas at high pressure and having a lateral access aperture, a clamping ring seated in said gas-containing part, a mild steel plate clamped between said ring and the other part in register with said lateral access aperture, said plate being insertable through said lateral aperture, the other of said par-ts having discharge apertures therein and a shearing portion confronting said clamping ring, said clamping ring having an annular groove in its plate clamping end surface and circumferential grooves in its outer periphery and spaced from said lateral aperture, and resilient annular sealing members each seating in one of said grooves.

5. A blasting device comprising a two-part cartridge adapted to contain gas at high pressure, and a mild steel plate clam-pcd between said parts, one of said parts having lateral discharge apertures therein and an end wall spaced from said apertures and said plate whereby a portion broken from said plate and propelled toward said end wall by said gas charge will achieve a high velocity before it strikes said wall, the plate-engaging end portion of said laterally apertured part defining a shear ring outlining the portion of said plate to be broken by said gas charge, the inner transverse dimension of the shear ring portion of said laterally apertured part being smaller than the inner transverse dimension of the remainder of said laterally apertured part.

6. A blasting device comprising a two-part metal cartridge, one part being adapted to contain gas at high pressure, the other part having an end wall and lateral discharge apertures spaced from said end wall, a plate clamped between said parts, said plate being formed of a metal of greater ductility and less strength than the metal of which said cartridge is formed, the end surface of the gas-containing cartridge part which clamps said plate having an annular groove therein, and an annular resilient seal seated in said groove and engaging said plate, said grooved p-art having a vent establishing communication between the gas-containing chamber of said cartridge and the innermost part of said groove.

7. A blasting device comprising a two-part metal cartridge, one part being adapted to contain gas at high pressure, the other part having an end wall and lateral discharge apertures spaced from said end wall, a plate clamped between said parts, said plate being formed of a metal of greater ductility and less strength than the metal of which said cartridge is formed, said gas-containing cartridge part having an internal circumferential shoulder spaced from its end, a clamping ring within said last named cartridge part normally bearing against said shoulder, a circumferential sealing member encircling said ring, and an inwardly projecting part on said last named cartridge part, said ring having a reduced portion adjacent to said inwardly projecting part and a shoulder confronting and engageable with said inwardly projecting part for restraining releasing movement of said ring.

8. A closure assembly for the discharge end of a reuseable pressure resistant blasting tube of the type wherein the said discharge end is internally threaded which comprises a hollow discharge head in threaded engagement with said tube, a shear-disc adjacent to the interior end of said discharge head and of larger diameter than the inner diameter of said discharge head, and a sleeve within said tube adjacent the said shear-disc on the side opposite the said discharge head, said sleeve being of slightly smaller diameter than that portion of said tube and having at least one peripheral groove containing a resilient sealing element of greater thickness than the depth of said groove, and an annular ridge of a metal harder than the shear disc at the end of the sleeve adjacent to said sheardisc.

9. An assembly as claimed in claim 8, wherein the resilient sealing elements are of rubber-like material.

.sf/revel il 10. An assembly as claimed in claim 8, wherein the ridge is formed integral with said sleeve.

11. An assembly as claimed in claim 8, wherein the ridge has its highest portion at the inner edge of said sleeve.

References Cited in the le of this patent UNITED STATES PATENTS 174,035 Vick Feb. 22, 1876 12 Myers Ian. 31, 1939 Christensen Nov. 21, 1939 Berry Mar. 23, 1943 Williamson Mar. 28, 1950 Loving Apr. 28, 1953 i Swed Aug. 11, 1953 Hessen et a1 June 4, 1957 FOREIGN PATENTS Switzerland Aug. 1, 1935 OTHER REFERENCES Kent: The Mechanical Engineers Handbook, 12th edition, Design and Production volume (1950).