US2098529A - Method and apparatus for charging blasting cartridges - Google Patents

Description

NW. 9, 1937. F. H. ARMSTRONG 2,098,529

METHOD AND APP.RATUS FOR CHARGING BLASTING CARTRIGES Filed March 16, 1936 3 Sheets-Sheet l gmwntoz Nov. 9, 1937. F. H. ARMSTRONG 2,093,529

METHOD AND APPARATUS FOR' CHARGING BLASTING CARTRIGES Filed March 16, 1936 s Sheets-Sheet 2 Roma Nov. 9 1937. F. H. ARMSTRONG 2,098,529

METHOD AND APPARATUS FOR CHARGING BLASTING CARTRIGES Filed March 16, 1936 5 Sheets-Sheet.3

J N a l I i I I I (r I a I I I es I \z k I I i i I I 1 I i p N l i R? l I I I 1 I &

Q a $5 k a? i J k R flail/ rusting Patented Nov. 9, 1937 UITED STATES METHOD AND APPARATUS non cmmcmo BLASTING canrnmcas Frank H. Armstrong, Chicago, 111., assignor to Safety Mining Company, Chicago, 111., a corporation Application-March 16', 1936, Serial No. 69,209

9 Claims.

This invention relates to a method and apparatus for charging blasting cartridges.

It has been definitely established that highly compressed gases, such as air, when liberated suddenly from an indestructible cartridge or shell constitutes a very effective means for breaking down coal, or the like. No completely satisfactory method and apparatus, however, has been developed for economically and safely charging the cartridges or shells with the highly compressed gas.

One system which has been tried involves the precharging of the cartridges or shells at a central charging plant, located either adjacent the entrance to the mine or in a principal corridor of the mine, and then transporting the charged shells or cartridges to the rooms in which blasting operations are to'be performed. This system is very satisfactory from an economic standpoint. Due to the high pressures at which the cartridges are charged with compressed gas, this system, with the cartridge or shell structures which have been developed up to the present time possesses a low safety factor and is considered too dangerous to use. It has been discovered that cartridges will satisfactorily pass all tests and inspections prior to being placed in service, which tests include subjecting the cartridges to .a hydraulic pressure in" the neighborhood of 30,Q00 lbs. per square inch, and yet after some cartridges which are put in use are charged several times minute defects will develop intoserious fiaws which render the shells unsatisfactory for further use. Due to the difiiculties involved in using the precharged method, efiorts have been made to develop a satisfactory system or method of postcharging cartridges; that is, charging the cartridges with highly compressed gas after the cartridges have been placed in drill holes or blast holes in the mine wall to be broken down. Two methods have been tried for post-charging cartridges. One method consists of connecting a cartridge, after it is placed in a drill hole and the hole tamped, to a portable compressor unit. A second method of post-charging cartridges which has been tried consists of charging .a.

There are three principal objections to the useof portable compressors for post-charging car-- tridges. It has been necessary to specially develop portable compressorunits to be used for this purpose. These units are extremely expensive and require approximately 60 horsepower per unit to operate. Each unit has a capacity of charging enough cartridges to break down from 700 to 750 tons per working shift. This means that a large mine would have to operate several units to turn out a day's quota. It will be appreciated, therefore, that the operation of these several units would add very materially to the power load at a time when the normal power load of a mine is at its peak. This is a very serious objection becausevery few, if any coal mines now in operation have any surplus power during the working shift. It, therefore, would be necessary for a mine, before it could be operated under this method for post-charging cartridges, to have its power developing equipment replaced by generators or .alternators having a much greater output of power. I

The second serious objection to the use of portable compressors for post-charging cartridges is the interference with tramc. Each of these compressor units has to be moved from. face to face the same as other equipment under ground. The trackage systems, as now laid out, are not capable of satisfactorily handling this additional tramc.

The third objection is that this system of using portable compressors is not sufiiciently flexible. For one compressor unit to be able to operate at a. capacity of 700 to 750 tons per working shift, the coal to be broken down must be fairly well concentrated. This condition seldom exists.

The second system which has been tried for post-charging cartridges, as stated above, consists of charging a series or bank of receivers with compressed air at a central charging plant. This system overcomes to acertain extent the three principal objections outlined above which are possessed by the system employing portable compressor units. The principal objection to this second system is its small capacity.

This system of post-charging cartridges from receivers has been carried on in the following manner: each receiver has a volumetric capacity equal to several of the blasting cartridges or pressure which can 'be developed is approximately 14,000 lbs. per square inch. The receivers, therefore, have been charged with compressed gas at pressures ranging from 12,000 to 14,000 lbs. per square inch. The cartridges preferably are charged with compressed gas at approximately 8,000 lbs. per square inch.

When one of these series or banks of receivers is first placed in use, the cartridges to be charged are successively connected to the first one of the receivers. Cartridges are fully charged from this receiver until the pressure in the receiver drops below the desired charging pressure of the cartridges. From that time, it is necessary to first connect a cartridge with the partially exhausted receiver and place as much of a charge in the cartridge from this first receiver as possible. The balance of the charge then must be obtained from the second receiver of the series or bank and to accomplish this the cartridge must be disconnected from the first receiver and then connected to the second receiver. This procedure is followed until the pressure in the second receiver drops below the desired blasting pressure of the cartridges. From that time on, succeeding cartridges must be charged by being connected with three receivers by receiving a portion of its charge from the first receiver, then a further fraction of its full charge from the second receiver, and finally be brought up to the desired blasting pressure from thethird receiver. This method of procedure is continued with successive cartridges until no receiver units which actually have been employed in carrying out this system have been capable of charging in the neighborhood of twenty-three cartridges. It will be appreciated that the number of receivers and the size of the respective receivers in a unit of this character are limited by the permissible overall dimensions for units operating underground in mines. These units have never been capable of producing more than 150 tons before they must be recharged. It, therefore, necessitates the use of five or six of these units or the recharging of a single unit five or six times to equal the capacity of a single portable compressor unit. Due to the low capacity of these receiver units, this system has not been entirely satisfactory.

It is the primary object of this invention to provide a method and apparatus for efllciently and economically charging blasting cartridges by overcoming all of the objections referred to above' in connection with the two previously tried systems employed for post-charging cartridges, Other objects and advantages of the invention will be apparent during the course of the following description. I

In the accompanying drawings forming a part of this specification and in which like numerals are employed to designate like parts throughout the same,

Figure 1 is a top plan view of the blasting carwith the operation ofthe .same.

tridge charging apparatus embodying this invention and operable to carry out the methods described and claimed herein,

Figure 2 is a vertical sectional view of the apparatus disclosed in Fig. 1,

Figure 3 is a vertical sectional view taken at right angles to Fig. 2, on lines 33 of this latter figure, and Y Figure 4 is a detail vertical sectional view taken on line 4-4 of Fig. 2 and illustrating a form of intensifier incorporated in the apparatus embodying this invention.

In the drawings, wherein for the purpose of illustration is shown a preferred embodiment of this invention, the numeral 5 designates in its entirety a wheeled truck which is designed to travel along the trackage system of a mine. The platform of this truck has mounted thereon a pair .of parallel, substantially triangularly shaped blocks 6 which support a tank or receptacle I with the bottom wall Ia. of the tank inclined. The side walls of the tank are shaped and proportioned so that the top edges of the I same all reside in a common horizontal plane.

Mounted upon the bottom wall 1a of the tank or receptacle 1 are a plurality of receivers or tanks 8. These receivers or tanks are arranged to extend longitudinally of the inclined bottom la. so that one end of each receiver or tank will be located at a lower level than the remaining end. The receivers or tanks are, necessarily, made to withstand considerable internal pressure and are each provided with threaded plugs 9 at the opposite ends of the same.

Figure 2 shows partly in section and partly in elevation one of the receivers '8. It will be noted that the lower end of this receiver has a passageway |0 formed therein which communicates with the lowest point of the interior of the receiver. The upper end of the receiver is provided with a passageway H which communicates with the highest point of the interior of the receiver. Each of the receivers illustrated is provided with passageways l0 and H.

Figures 1 and 3 illustrate three of the four receivers 8 as having their passageways l0 connected to the passageways ll of adjacent receivers by means of a pipe or conduit l2. These three conduits function to connect the four receivers in series.

Figures 1 and 3 disclose the passageways ll of one of the end receivers as having suitably connected thereto a conduit l3 which is controlled by a manually operable valve l4. Figures 1 and 2 disclose the passageway In of the receiver at the opposite end of the series as being connected to a conduit l5. Figure 2 discloses this conduit as having a drain cock l6 located therein at any desired point.

Figure 4 discloses in section an intensifier which is illustrated in Figures 1 and 2 as being incorporated in this apparatus. The details of this intensifier are disclosed solely for the purpose of fully a'cquainting one skilled in the art It is to be understood, however, that I do not want to be limited to the particular form of intensifier illustrated or to the particular type of device represented by this intensifier. I fully appreciate that other types of pumps, or the like, may be used, such for example as, a Triplex plunger pump. The intensifier structure illustrated is preferred because it is so much more compact and less expensive than other typesof units which can be employed.

20 and the two plungers or pistons 2| are operatively connected to the motor piston I 9.

. fl'helim'otor piston l9 may be driven by any suitablejfiuid, such as steam, compressed air, or the like, however, I have determined that it may be operated most economically and satisfactorily in a mine by'inieans of oil under pressure, which is supplied by a motor driven rotary pump. Reverse movement of the motor piston is accomplished by means of the valte mechanism generally designated by the reference character 22. It is believed that this type of intensifier or pumping unit is well understood and further explanation ofits structural features and mode of operation is believed to be unnecessary The outer end of each pumping cylinder 20 has connected thereto a coupling 23 which is provided with two branches 24 and 25. Each one of these branches has a check valve 26 incorporated therein.

, The branches 24 of both couplings 23 are con-' nected by the piping 21. Both branches 25 of the couplings 23 are connected by piping 28.

Figures 1 and 2 disclose the piping 21 as being connected to the conduit 15 which communicates with the pasageway ill of one of the end receivers, as described above. Figures 2 and 3 disclose the piping 28 as being connected to. a conduit 29 which extends to and is connected with the lowest portion of the tank or receptacle 1, as at 30.

The tank or receptacle 1 {is intended to be filled with a suitable fluid, such as the water 3i illustrated in Figures 1 to 3, inclusive. It now will be seen that each inward stroke of both of the pumping plungers orpistons 2| will result in drawing water from the tank or receptacle .1 into a pump cylinder 20 while' each outward stroke of the pistons or plungers 2| will result in water being forced from the pumping cylinders 20 through the conduit I5 into one of the end receivers 8. s

The method of operating this apparatus to charge blasting cartridges will be described as follows: v

The conduitl3 is to be connected to a compress'or unitfpreferably of the stationary type and located adjacent the entrance to the mine or in a principal corridor of the same. After this connection has been established, the receivers 8 are to be charged with compressed gas, such as air, to a pressure of approximately 12,000 lbs. 'per square inch. After the receivers are fullycharged, the valve I 4 is closed and the receiver unit is moved to a desired location in the mine. When the receiver unit is to'be employed for charging blasting cartridges, the cartridges are connected to the conduit l3, and the valve I opened. Successive cartridges may be charged from the receivers 8, which are connected in series by the conduits I2, until the pressure of I the gas within the receivers drops to the desired blasting pressure of the cartridges. As successive cartridges are charged from the receivers, the intensifier is simultaneously operated and functions to force into one extremity of the se-' ries of receivers water 3l-at the same rate as compressed air is discharged from the opposite extremity of the series of receivers. In other 93 words, the intensifier functions to force water into the receivers at a rate to maintain the compressed gas charge at a constant pressure equal to the desired charging pressure of the cartridges gas of suflicient' volume to charge a single cartridge.

It will be appreciated that'this type of receiver unit may be chargedfrom stationary compressor units during the ofi shift so that'the power required to operate the compressor. or compres- -three cartridges for the sors of a mine will not be used during the peak load period. A suitable number of receiver units of this character may be charged and distributed to strategic points in the mine during the on shift and then used during the working shift to charge the blasting cartridges. The use 'of this type of receiver unit, thereforedoes not create a trafflc problem. Because all of the compressed gas may be discharged from the series of receivers, this type of unit has'a capacity of three times the capacity of the type of receiver unit described above as being employed in one of the old systems for post-charging cartridges. For example, a receiver unit of -the character embodying'this invention having a capacity equal to the capacity of a receiver unit of the old method is capable of shooting sixty-seven cartridges as compared to the capacity of twentyold type of receiver unit. The power required tooperate the intensifier, shown in detail in Fig. 4, is about of that which would be required to pump the same amount of air so that several of these units could be operated .without using very much power on the working shift. v

After the receiver unit of this invention has been completely discharged, it is again returned to the charging compressor and connected thereto by means of the conduit l3. As the compressor forces a new charge of compressed gas into the series of receivers, the incoming gas will force the water from the receivers. The water may be returned to the tank or receptacle 1 by opening the drain cock Hi.

It is. to be understood that the form of -this invention. herewith shown and described is to be taken as a preferred example of the same, and that various changes in the shape, size, and

arrangement of parts will be resorted to without departing from the spirit of the invention or scope of the subjoined claims. I

Having thus described the invention, I claim: 1. A portable'blasting cartridge charger comprising a wheeled truck, a liquid receptacle mounted on the truck, a plurality of receivers be charged, and means mounted .on the truckfor forcing liquid from the receptacle into the series of receivers as cartridges are charged with compressed gas therefrom to maintain the gas remaining in the receivers at the desired charging pressure of the cartridges.

2. A portable blasting cartridge charger comprising a wheeled truck, a liquid receptacle,

means for mounting said receptacle on the truck receiver to be charged with the bottom of the receptacle inclined, a plurality of receivers connected in series and longitudinally supported on said inclined bottom, means for connecting the higher and lower ends of difierent receivers to join all of the receivers in series, means for connecting thehigher end of the receiver at one end of the series to a source of compressed gas to charge the receivers to a pressure at least equal to the desired charging pressure of the cartridges and for connecting the receivers to the cartridges to be charged,- and means mounted on the truck for forcing liquid from the receptacle into the lower end of the receiver at the other end of the series at the rate of discharge of compressed gas therefrom into cartridges to maintain the gas remaining in the receivers at the desired charging pressure of the cartridges.

3. A portable blasting cartridge charger comprising a wheeled truck, a plurality of receivers connected in series, means for supporting said receivers on said truck, means for connecting the series of receivers to a source of compressed gas to charge the receivers to a pressure at least equal to thedesired charging pressure of the cartridges and, for connecting the receivers to the cartridges to be charged, a source of liquid at atmospheric pressure mounted on the truck, means mounted on the truck for forcing liquid from its source into the series of receivers as cartridges are charged with compressed gas therefrom to maintain the gas remaining in the receivers at the desired charging pressure cartridges, and means for returning the liquid to its source as the receivers are again charged with compressed gas. V

4. A blasting cartridge charger comprising a with compressed gas, means for supporting said receiver at an angle to the perpendicular, means receiver to a source of compressed gas to charge the receiver to a pressure at least equal to the desired charging pressure of the cartridges and for connecting the receiver to the cartridges to be charged. a-source of liquid, means for forcing liquid from its source into the receiver as cartridges are charged with compressed gas therefrom to maintain the gas remaining in the receiver at the desired charging pressure of the cartridges, and means for returning the liquid to its source as the receiver is again charged with compressed gas.

5. A blasting cartridge charger comprising a liquid receptacle, 9. receiver constructed to hold gas compressed to a high pressure positioned within the receptacle, means for connecting the receiver to a source of compressed gas for charging the receiver to a pressure at least equal to the desired charging pressure of the cartridges and for connecting the receiver to the cartriaes to be charged, and means for forcing liquid from the receptacle into the receiver as cartridges are charged with compressed gas therefrom to mainof thei'or connecting the compressed to a pressure tain the gas remaining in the receiver at the desired charging pressure oi the cartridges.

6. A blasting'cartridge charger comprising a liquid receptacle, a receiver constructed to hold gas compressed to a high pressure positioned within the receptacle, means for connecting the receiver to a source of compressed gas for charging the receiver to a pressure at least equal to the desired charging pressure of the cartridges and for connecting the receiver to the cartridges to be charged, means for forcing liquid from the receptacle into the receiver as cartridges are charged with compressed gas therefrom to maintain the gas remaining in the receiver at the desired charging pressure of the cartridges, and means for returning the liquid to the receptacle as the receiver is again charged with compressed gas.

'7. A blasting cartridge charger comprising a liquid receptacle having one of its walls inclined, a receiver constructed to hold gas compressed to a high pressure supported on said inclined wall so that its respective ends are arranged at different levels, means for connecting the receiver to a source of compressed gas for charging the receiver to apressure at least equal to the desired charging pressure of the cartridges and for connecting the receiver to the cartridges in be charged, and means for forcing liquid from the receptacle into the receiver as cartridges are charged with compressed gas therefrom to main tain the gas remaining in the rewiver at the desired charging pressure of the cartridges.

8. The me hod of charging blasting cartridges while positioned within a the material to be broken down with a compressed gas at an eflective blasting pressure from a receiver having a'volumetriccapacity at least equal to the combined capacities of the cartridges to be charged and containing a supply of gas at least equal to the desired charging pressure of a cartridge, which comprises the steps of successively drawing off cartridge charges from the receiver, and maintainingthe compressed gas remaining in the receiver at said eflfective blasting pressure until the supply in the receiver is exhausted.

9. A method of charging blasting cartridges while positioned within a drill hole formed in the material to be broken ceiver unit having a volumetric capacity at least equal to the combined capacities of the cartridges to be charged and containing a supply of gas compressed to a pressure at least equal to the desired charging pressure of a cartridge, which comprises the steps oi. successively drawing off cartridge charges from the receiver unit, and supplying liquid to said unit at a rate equal to the rate of discharge of the gas from the unit to maintain the gas remaining in the receiver unit atthe desired charging pressure until the supply inthe receiver unit is exhausted.

FRANK H. ARMSTRONG.

drill hole formed in I down with a-compressed i gas at an eflective blasting pressure from a re-

Images