US3016015A - Blasting devices - Google Patents

Description

Jan. 9, 1962 E. c. FILSTRUP 3,

BLASTING DEVICES Filed May 14, 1959 FIG. 1

IN V EN TOR.

EDWARD C. FILSTRUP JR.

BY W 5 States 3,16,15 Patented Jan. 9, 1962 3,016,015 BLASTHJG DEVICES Edward C. Filstrup, St. Joseph, Mich, assignor to Olin Mathieson Chemical Corporation, East Alton, 11]., a corporation of Virginia Filed May 14, 1959, Ser. No. 813,230 7 Claims. (Cl. 102-25) This invention relates to blasting devices and more particularly to material breaking cartridges utilizing a gas under pressure as the work performing medium.

Material breaking cartridges using compressed gas to execute the required work are well known and widely used in the mining industry. Such cartridges or blasting devices are all reliant upon the sudden release of compressed gas to give a quasi explosive eifect. The precursor of this type of blasting cartridge consisted essentially of a cylindrical gas-containing cartridge having venting means. The cartridges were charged with gas under considerable pressure, sealed and then conveyed to the face to be worked. The compressed gas within these cartridges was released by elaborate remote control means. More recently, the practice has been to place an uncharged cartridge in the bore hole and pump gas through a suitable conduit into the cartridge in situ. Conventionally, these cartridges are formed of high strength materials and are provided with a relatively weak member which shears or ruptures so as to liberate the gas from the cartridge body. Since the amount of pressure that can be built up in the cartridge body is dependent upon the strength of the expendable member, the quantity of energy developed by the liberation of the gas can be controlled within relatively close limits. Such cartridges have met with general success in the field but are difficult to manufacture and maintain. They are conventionally fired at pressures in the neighborhood of 10,000 psi. and require a relatively large number of reliable seals to insure proper functioning. The manufacture and maintenance of such seals has in the past proved expensive and exceedingly inconvenient. Thus, the development of a shell having a minimum number of seals has long been recognized as a desirable goal. Furthermore, the current material breaking shells are difiicult to disassemble, repair and reassemble. In most instances, this must be done at a work bench and not in the area in which the shell is being used.

Therefore, it is an object of this invention to provide new and improved material breaking devices utilizing compressed gas. A further object of this invention is to provide a simplified device of this character having a minimum number of seals. Another object of this invention is to provide a shell having a rupturable release member that can be used a number of times. Still another object of this invention is to provide a compressed gas material breaking cartridge overcoming the disadvantages of the prior art.

The manner in which these and other objects are accomplished will be apparent from the following specification together with the drawing in which:

FIGURE 1 is a longitudinal sectional view of a device illustrating one embodiment of the present invention;

FIGURE Z is a longitudinal sectional view of a device illustrating another embodiment of the present invention;

FIGURE 3 is a perspective view partially in section of the sleevevalv'e employed in the embodiment shown in FIGURE 2; and

FIGURE 4 is a plan view of the shear plate utilized in the embodiment of FIGURE 2. p

Referring to FIGURE lwhich illustrates a preferred embodiment of the invention, an elongated tubular body formed of metal, reinforced syntheticplastic material, or

the like, of a strength to contain gasunder high pressures,

for example pressures from 6,000 to 20,000 pounds per square inch, is indicated generally at 1. Only a portion of this tubular body which may be of the order of 50 inches in length is shown. The outer diameter of the body is such that it may be set freely within a bore drilled in the face of the material, such as coal, to be mined and broken down. One end of the tubular body is provided with a neck portion of slightly reduced diameter which is screw threadedly attached to the head 2 as shown at 3. The seal between the tubular body and the head is completed by a suitably mounted annular resilient sealing means 4. A metallic sealing ring 5 is positioned adjacent the end of the tubular body 1. As shown in the drawing, the internal diameter of the metallic sealing ring 5 is slightly less than the internal diameter of the tubular body and the metallic sealing ring has its greatest effective cross sectional area facing the end of the tubular body. A peripheral flange 6 extends outwardly from one end of the metallic sealing ring and cooperates with shoulder 7 on head 2 so as to limit the movement of the sealing ring away from the terminal portion of the body. The sealing ring is slidable within the body and a sliding seal is maintained between these two members by means of an annular resilient sealing means such as O-ring 8 in groove 9. That end of the metallic sealing ring remote from flange 6 preferably terminates in a knife edge or an area of reduced diameter as shown at 10. This knife edge cooperates with the base of the sleeve valve 11 to form a metal-to-metal seal. Alternately, the end of the sealing ring can be fiat so as to provide a greater area for the metal-to-metal seal between the ring and the sleeve valve. The sleeve valve is slidable within head 2 and its movement therein is restricted in one direction by metal sealing ring 5 and in the other direction by the shear pin 12 as well as shoulder 28 on head 2 and the annular air pocket 13 formed by the juncture of the terminal portion of head 2 and end plate 14. The skirt 15 of valve 11 preferably terminates in an annular knife edge normally in contact with the shear pin 12. However, the cross sectional area of that portion of the skirt in contact with the shear pin can be modified depending upon the desired firing pressure and the strength of the pin. Although the end of the skirt as shown is beveled toward the interior, the terminal portion of the skirt can assume any desired configuration.

The shear pin 12 is normally held in position by reraining clip 17 attached by suitable means to piston 18 both of which are urged toward the shear pin by helical spring 19. Vent 20 in the base of sleeve valve 11 provides a means of communication between main chamber 21 and secondary chamber 22. The sealing of chamber 22 is completed by O-ring 23 between the piston 18 and the skirt 15 of the sleeve valve. The internal portion of the end plate 14 is preferably provided with a facing or shear ring 24 which cooperates with the knife edge 16 on the skirt to sever the shear pin.

In operation, shear pin 12 is inserted through slot 25 and is resiliently held between retaining clip 17 and shear ring 24. Compressed gas is then introduced into main chamber 21 by conventional means not shown and gas passes through vent 20 into the secondary chamber 22. Consequently, the pressure in these two chambers is substantially equal. Thus, piston 18 is urged into close proximity with shear pin 12 by air pressure in coopera tion with spring 19. As the gas pressure increases, metal sealing ring 5 is urged into tighter contact with sleeve valve 11 due to the diiferential effective areas of the metal sealing ring. As the pressure in the main chamber 21 increases to a point sufiicient to overcome the resistance of shear pin 12, the pin is cut by the knife edge 16 permitting the valve 11 to slide toward end plate 14 and away from discharge ports 26. The charge of compressed gas in main chamber 21 is thus completely and instantaneously released to the surrounding work face which is to be broken down. The movement of valve 11 after venting the ports is restricted by cooperation of flange 27 on the base of valve 11 and shoulder 28 in head 2 as well as by the cushioning effect of annular air pocket 12. When the charge of gas leaves main chamber 21 releasing the pressure therein, sleeve valve 11 is returned to its original position by helical spring 19. The portion of the shear pin remaining in slot 25 is removed and replaced by another shear member. The cartridge is then ready to be refired.

In the embodiment shown in FIGURE 2, a different type of shearable member and shearing means are employed. The same reference numerals will be used to identify those structural features common to both embodiments. Main chamber 21 with metal sealing ring 5 and O-ring 8 and knife edge 10 to provide a metal-tometal seal is identical to the structure described in connection with FIGURE 1. In this embodiment, however, the shear pin 12 is replaced with a rotatable shear plate 29. The piston 18 is urged into contact with the internal portion of shear plate 29 by helical spring 19 in the same manner as in the preceding embodiment. Stop pins 36 positioned in holes 38 in the skirt of sleeve valve 11 maintain the piston 18 in position. However, due to the planar configuration of the plate, retaining slip 17 can be eliminated. The entire periphery of the skirt 15 of sleeve valve 11 does not contact the shearable member 29 but only a portion of the skirt extends in the form of a projection 30 into contact with the shear plate. The preferred form of the sleeve valve is shown in FIGURE 3. This projection is generally small in relation to the circumference of the skirt and preferably represents an arc of about 10. The shear plate 29 is provided with a non-circular central perforation 31 as best illustrated in FIGURE 4. End plug 32 is provided with an interior terminal portion 33 having a cross sectional configuration similar to that of central perforation 31 in shear plate 29. The shear plate is ounted on this terminal portion 33 of the plug 32 as shown. The opposite end of the end plug 32 is provided with a key socket 34 or any other suitable wrench receiving means. Plug 32 is freely rotatable and is held in place by end nut 35. The peripheral portion of shear plate 29 is positioned away from the main body of plug 32 by shear ring 24.

The shell shown in FIGURE 2 operates much in the same manner as the one previously described. As gas under pressure is introduced into main chamber 21, metallic sealing ring 5 is urged against the basal portion of sleeve valve 11 to form a metal-to-rnetal seal and the gas passing through vent into chamber 22 forces piston 18 into tight relationship with shear plate 29 and member 32. The movement of the valve 11 away from ports 26 is retarded until the pressure built up in main chamber 21 is sufficient to overcome the resistance of the shear plate 29. When the force exerted by the gas in V the main chamber against sleeve valve 11 exceeds the sum of the opposing force exerted on the sleeve valve by the gas in the secondary chamber 22 and the resistance offered by spring 19 and shear plate 29, projection 30 suddenly passes through a portion of the shear plate and the valve slides away from and exposes ports 26. Here again, the movement of the sleeve valve after venting is restricted by cooperation between flange 27 on the valve and shoulder 28 on the head. After the cartridge has been fired, the sleeve valve isreturned to its original position by helical spring 19. Plug 32 is rotated through an angle of about 22 by means of key socket 34, resulting in corresponding rotation of shear plate 29. V The projection 35.) on the sleeve valve is then opposed by another solid portion of the shear plate and the shell is in condition for refiring.

The projection 30 on the valve 11 normally has a thickness substantially equal to the thickness of the valve skirt 15 but can vary greatly in width. This projection can thus constitute from'3% to slightly less than 50% of the periphery of the skirt 15. The number of shots that can be fired with one shear plate increases as the width of the projection decreases. Thus, when the projection extends about half way around the skirt, only two shots can be fired with one shear plate. However, the number of shots can readily be increased to about 16 or 18 by reducing the width of the projection to about a 10' are on the periphery of the sleeve valve skirt 15. Variations in the width of the projection also provide a means of determining the pressure at which the gas in the main chamber will be released. In addition, the firing pressure can be controlled by the thickness and strength of the shear plate. While in this embodiment, the projection penetrates the peripheral portion of the shear plate, it should be understood that such penetration can be made through more centralized locales in the shear plate.

After all portions of the shear plate have been used, it is readily removed by unscrewing end nut 35. Removal of this not frees rotatable plug 32 and the shear plate is easily removed through slot 37. The condition of the shear plate and the requirement for replacing it can readily be observed through slot 37.

The shell of this embodiment can be readily provided with means to rotate the shear plate each time the sleeve valve goes through its firing cycle. In this way, the shell can be fired automatically until all usable portions of the shear plate have been expended.

While two specific embodiments of the present invention have been shown, various modifications will suggest themselves to those skilled in the art. Thus, various types of valves, springs and resilient sealing members can readily be employed in place of those specifically disclosed. Although the present specification is directed to blasting devices, it will be appreciated that the invention is applicable to any other type of apparatus in which a sudden release of gas under pressure is required.

What is claimed is:

1. A blasting device comprising a substantially cylindrical body, a pressure chamber within the body having a lateral outlet, means for introducing gas under pressure at one end of said body, the opposite end of said body having an end wall provided with intersecting longitudinal and transverse passageways, a pressure responsive sleeve valve slidable in said chamber and normally positioned to span and seal said outlet, the valve having a smaller effective cross-sectional area on that side of the valve facing said end Wall than on the other side of the Valve, a skirt on the sleeve valve extending toward said end wall to a shear member, the skirt forming a secondary Chamber, means of communication between the pressure chamber and the secondary chamber, an imperforate piston slidably sealed within the secondary chamber, and resilient means normally urging said piston into retaining position with the shearable member.

2. A blasting device comprising a substantially cylindrical body having a main chamber for containing a charge of compressed gas, a lateral outlet for the gas, a pressure responsive sleeve valve slidable in said main chamber and normally positioned to span and seal said outlet, the sleeve valve having a skirt extending away from the main chamber and terminating in contact with a shearable member, a secondary chamber within the skirt of the sleeve valve, means of communication between the main chamber and the secondary chamber, the sleeve valve having a larger effective cross-sectional area in the main chamber than in the secondary chamber, imperforate retaining means for the shearable member slidably sealed within the secondary chamber, and resilient means normally urging the retaining means into operative contact with said shearable member.

3. A blasting device comprising a substantially cylindrical body having a lateral outlet, the body adapted to contain a charge of compressed gas and to release the charge at a predetermined pressure, a pressure responsive sleeve valve slidable in said body and normally positioned to span and seal said outlet, a rotatable reusable shear member, an imperforate shear retaining means slidably sealed in said valve, and a projection on the sleeve valve normally in contact with a minor portion of said shear member.

4. A blasting device comprising a substantially cylindrical body having a main chamber for containing a charge of compressed gas, a lateral outlet in the body, a pressure responsive sleeve valve slidable within said main chamber and normally positioned to span and seal said outlet, a skirt on thesleeve valve extending away from said main chamber and terminating in contact with a shearable member, a secondary chamber within the skirt of the sleeve valve, means of communication between the main chamber and the secondary chamber, the sleeve valve having a greater effective cross-sectional area within the main chamber than in the secondary chamber, a slidable sealing ring about the internal periphery of the main chamber and in sealing relationship with the sleeve valve, the sealing ring having differential effective surface areas normally urging it in the direction of the shearable member, an imperforate piston slidably sealed with the secondary chamber for retaining the shearable member, and resilient means within the secondary chamber normally urging the piston toward said shearable member.

5. A blasting device comprising a substantially cylindrical body having a main chamber for containing a charge of compressed gas, a lateral outlet for the gas, a pressure responsive sleeve valve slidable within said main chamber and normally positioned to span and seal said outlet, a skirt portion of the sleeve valve extending away from the main chamber, a projecting segment of the skirt portion terminating in contact with a shearable member, a secondary chamber within the skirt of the sleeve valve, the sleeve valve havinga greater eflective cross-sectional area in the main chamber than in the secondary chamber, means or" communication between the main chamber and the secondary chamber, an imperforate piston slidably sealed within the secondary chamber for retaining the shearable member in operative position, and resilient means within the secondary chamber normally urging the piston into contact with said shearable member and urging the sleeve valve to a position spanning said outlet.

6. The blasting device of claim 5 in which the shearable member is a rotatable disc.

7. A blasting device comprising a substantially cylindrical body having a main chamber for containing a charge of compressed gas, a lateral outlet for the gas, a pressure-responsive sleeve valve slidable in said main chamber and normally positioned to span and seal said outlet, the sleeve valve having a skirt extending away from the main chamber with at least a portion of the skirt terminating in contact with a shearable member, a secondary chamber within the skirt of the sleeve valve, means of communication between the main chamber and the secondary chamber, the sleeve valve having a larger effective cross sectional area in the main chamber than in the secondary chamber, an imperforate piston slidably sealed within the skirt of the valve, said piston retaining the shearable member in operative position in response to pressure within the secondary chamber, and resilient means normally urging the retaining means into contact with said shearable member, said shearable member being adapted to be penetrated by at least a portion of the valve skirt acting in response to main chamber pressure.

References Cited in the file of this patent UNITED STATES PATENTS 2,435,116 Armstrong Jan. 27, 1948 2,750,886 Filstrup June 19, 1956 2,794,395 Hesson et a1 June 4, 1957

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