US2566948A - Multiple blast - Google Patents

Description

G. A. LYTE MULTIPLE BLAST Sept. 4, 1951 4 Sheets-Sheet 1 Filed April 7, 1948 George A. Lyte Sept. 4, 1951 G. A. LYTE 2,566,948

MULTIPLE BLAST Filed Apr il '7, 194a 4 Sheets-Sheet 2 FIG. IA

Sept. 4, 1951 G. A. LYTE 2,565,948

MULTIPLE BLAST Filed April 7, 1948 4 Sheets-Sheet :5

Isi-

Geovga A. Lym

Sept. 4, 1951 G. A. LYTE. 2,566,948

MULTIPLE BLAST Filed April 7, 1948 4 Sheets-Sheet 4 Ilatentecl Sept. 4, 1951 UNITED STATES PATENT OFFICE 8 Claims.

This invention relates to blasting devices and has for its principal object the provision of a portable timer which will permit the use of a series of firing circuits operated successively at regular intervals of time which would be in the range from two thousandths of a second up to perhaps an eighth of a second or more.

A further obJect of the invention is to provide a method of distributing to a series of firing circuits, each including at least one detonator or firing element, the full current of the power line in a manner to minimize the shock or vibration of the blast together with an improved breaking down of the formation, whether it be rock, ore, soil, etc.

A further object of the invention is to provide a blasting mechanism which will give complete safety and yet can be placed conveniently near the blast and be controlled from a remote point. Other objects of the invention relate particularly to details of construction and are more particularly pointed out in the claims.

In blasting operations, particularly where the material which is blasted is to be used, it is desirable to break down a large portion of a clifi, for example, without injury to the formation but it is also desired that the concussion caused by the blast shall be as small as possible. In the present machine this is obtained by having a number of circuits up to 150 or more, twenty being illustrated, to be fired in rapid succession, following one another With sufhcient rapidity so that the burden of one charge is not thrown out of the way of the mass discharged by the next blast. In this way the concussion is reduced to a small fraction of what it otherwise would be and the thud of the explosion is rather a mufiled sound than a sharp burst as in previous art. By spacing the several blasts thru a short period of time the waves from one blast modify the waves from the next succeeding blast and rather tend to cancel out the earth vibration.

Previous workers have devised means for firin two circuits consecutively with a brief pause between them but the number of circuits possible with the usual push down blasting machine is limited to two and the purpose of these earlier blasting machines was to make the entire limited output of the machine available for the second shot by breaking the first circuit before closing the second circuit.

In past times I have successfully made multiple blasts with individual detonation initiatin agents having different elements. In this way I can give a simple impulse to as many detonators as the electric current will take care of and since the different detonators fire at different times it is possible to obtain some of the advantages secured in the present case. The difficulties are so great, however, that I no longer use this old method. Obviously it was diificult to secure the proper timings and the nuisance of having to select the appropriate detonators was'considerable. In the present case all of the detonators are identical and the entire timing is obtained automatically by the machine.

In the drawings:

Figures 1 and 1-A are top plan views of my device with the cover and panel binding posts removed.

Figure 2 is an end View with one side removed.

' Figure 3 is a. partial vertical section taken on line 3--3 of Figure 1.

Figure 4 is a section on line 44 of Figure 1.

Figure 5 is a side elevation of the rack.

Figure 6 is a wiring diagram.

Reierring first to Figure 2, for convenience of transportation my device is built into a case It much like an elongated tool box, with a leather grip ll, hinges l8, and suitable suitcase catches l9. All of the mechanism shown in Figure 1 is hidden, when the box is open, by the Bakelite panel 15, carrying the twenty individual circuit binding posts l6 and the three main terminals, of which only the common terminal H is seen in Figure 2 as this post hides the two power line terminals 8i] and BI alined with it. In the bottom 01' the wooden box, I mount a relatively thick plate of aluminum alloy 20 resting on a rubber gasket 2i and held in place in the box by a suitable number of cleats 22 only two of which are illustrated. It is advantageous to secure the metal base plate against lateral movement and for this reason a number of screws such for example as 23 pass from the aluminum alloy plate thru the rubber gasket and into-the bottom panel of the box.

Referring now more particularly to Figure 1 the switch mechanism is carried on an assembly block 24 supported from the aluminum base 20 as by a number of spacer posts 25 of insulating material and being secured by bolts such as 26 to secure the desired rigidity. An auxiliary block. 21 is mounted in the center of the assembly block 24 and supports a portion of the leaves of the switches. A recess or groove 30 is cut into the assembly block 24 serving as a path for a rack 31 driven by a pinion 28 on the reduction gearing shaft 29 of gearing mounted in box 31 and driven by motor M. The motor and reduction gear may 3 be purchased as a unit under the name ratiomotor but obviously the sole purpose of the motor is to drive the pinion and therefore any other means such as a spring motor could be substituted with a loss of efficiency to drive the rack.

Except for the necessity of accurate timing, such as is desired here, the rack bar could be pushed in by hand but as indicated if this were done the-mime. required te; push it' -in would vary and this iseundesir'ables; Another important rea-, son for using the motor driven pinion is that if the device were to be operated by hand the; mechanism would necessarily have to be removed.

quite far from the blast because of safety whereasin the present case since the box is .ra ther;;low;1r V rack bar strikes the multiple contact switch opand does not turn over under any normal condition the box could be putrclose-to-the-bla'st and the operator can be at a very considerable distance from the box as all he needs to do is close the current to; ,the ,1003% A" rather heavy arigle'vpl. .QZJL is secured to therear edgeofljthe .a'sisemblyblockffl so that its tip slightly overlies lg roove' 3ll and enages the t'op ot the' rack bar so as to. hold it n h p per path,-v Al e' iieso f spri s are iriounted side; by sidegat or near thebottom edge of auxiliarvbloclg, 21 andleach has a down turned" end Mjpr J'Qcting inIthe path of the rack, that is they extend slightlydown into the rectangular channel 30. these springs 33 are integral Witlijor'fotherwise o n t d to a, ansve set ortio v 5 which 'receiv u ntiasMi lennial numbered .36. o the terminal post I! on'the Bakelite panelv l5 above. Thecurrentconsequently ,flows s'imul i o s to ll of the owniturl ed n s 3 Directly abovethe bank or leai.,sp series of separat e upp er switch rave 38 each having a wire,39.;ihdividHaLfiQ ,1 ,pwnpartic'ular circuit. As shown there ouldbetwenty of these Springs andZil wires eachil'eading to the binding post It of? itsjown' i' idualfcircuit which latter would containird one to fifty or more cartridges, T esesee; at rcu'itsare successively energized with a; tgtimefand a time interval, ches m n lbestI The rack bar 3! in additipn tout'he' usual teeth 0 a .,a,s oq h.,u per ur ace i w ich cut aside recess 42.,the .,bottom of, thisrecess, me n moothlxasat a e-w h a c mm e prow as A stop 45llimits'moyeinent. 01 the rackbar for as the raclg bar S m vedgm the left in, Fige the s p 5: enga es gme opt onal gui bracket 4 ni' hes de ofqthebo m helocat n of this stop 51' ,n efe ablrs h tha t cam-.- ming prow v d l tof ,the rack;, 3l will reach the nearest springj3 at thetin eithe motor M is revolving at full spjg and therefore the rack will be moving at a uniforrn rate, making the intervals b lv eeatn fir. aip suc es ive circuits almost exactly alike. I As the cammingi prqw Aleneaees ,the. ,downturned end 34,of thf-file lleadspring 33 the latter is raised until, contact,is madefwith the downturned end 49 0f theQsuperposed leaf spring 38. This action completes an electricw circuit, as will; later be explained, t JthebfirstDneof thefiring circuits. A slightly farther movement, of, the rack bar 3| will permit the'down-turned end 34 to lower on the sloping; curved portion,43' of the recess 42 so thatj as soon as theleaf 331 drops into the [recess the current will be shut ofi from the first circuitandfalmost immediately thereafter willbe delivered to the,seconclfcimuit;- In some of my models I have increased the 'dis- The opposite'ends of 4 tance between the points 43 and M at the nose of the rack bar so that the first circuit is not opened until an appreciable time after the first circuit has been energized, however, I desire that this period be extremely brief or omitted entirely because at times the bridge wires of a detonator are short circuited and if two circuits were on for an appreciable time there would be at: least ta possibility, of draining the; second circuit because oilthe shortfjrri thee'firstiicircuit. The rack bar under the urge of the pinion 28,

driven by any means desired, continues successively, to raise all twenty of the leaf springs 33.

Immediately after engaging the last of the s rineefi-nsers 33 the camming prow 44 of the I eratinglever il which like the spring leaves 33 is ,in,,the; path of the rack bar 4|. This lever is secured to a multiple switch shaft 5| mounted in bearings 52, The shaft .5l extends at, the right handjside in Figure f1fbeyondthebearing, to iiiountfan armlfifi constantly-urged upward by the spring 'fifi against, a suitable stop: 56"whlc'h=- limits downward movement: of the"point "off-the li-iverjefii The shaftSI carries.-a membertwhich" is called a comblan'dis numbered, 60. This comb could well be" a single sheet of m'etalfb'utl 'much" prefer to cut slots in itjas sh'own'"at..6'l tOTfOI'm individual Qfingers- 62 so that ?when this conib engages simultaneously all twenty of thefleaves 38 each leaf, Willi be pressedfolefinitelyand'firmlyf The. objectfof, this movement is! to'insure that ii any one of. the twenty fifing circuitsi'was notf energized 'at'th'e proper timeitwill now""be 'en-" ergized.v ,WhileLhave never had.a failiireby' any means,.fonthefraoki to operate all ofthe circuits I feeljthfat' the. comb'should be isedfthis' being merely aI'safety measure. i Located jbetween the. lever 50 .and the bearing 52 at the ri ht -there is" an" important safety ele' ment, which is a cut offfswit'ch to insure 'ag'ainstl improper, operation; f "The slower 1eaf"oi the switch $4 is numbered 651' and has alprojection V v 66 which canibe .ehgagedibygcorresponding con: I tactflelementlltfi on;the ,upper leaf "68of "this switch. .64. The .uppen lie'aff 768"? projects down=' wardly 'asgat. fiql'into ,thepath of the rack bar: As the rackibar passes thispoint it"engages the, downaturnednend and, liitspi't' slightlys'o as toseparate the contact points ,66'5'a1'1'd. 61. This" actionshuts ofijalliicurrlentflto, the box andit's; contents; A slight" further movement of the prow" ofithe rack. bar} Liengages, theplunge'r lUjof a dash ,p'oft ,arrangementlconsisti'rig of a cylinder;

11 containing. asprmg zvm, cushion the motion of the rackbarQland 'finallylto lin'iitl'it as when? the set, screw 13 Iengagesfthe'end.H'bf the slot infth, barrel of thegjdashmotjelementii The switch. '5 L, as 'jpi evidusly stated, 'in'faddi' tion to being a ,cut Ioif iisia safety device acting. as follows When the,1rackbar 3 I 1 is all the way in and en agesfiie plunger 16" no currentv is de llver'ed ftd the, device but ifjan operator-"should unwittingh ltryto move the'raclc'bar out .'(to the left) the upper spring leaf B8fin lowering would establish'jcurrent to the jmUtUl" 351"Si1'1'6t5 the motor' revolves in only-one direction it would pullthe rack bar out'of the operators ha'nds and j'return it properly ill'tOfjCOl'ltQZClT witlr'tlie' plunger 79'; Consequentlytherer-isno" possibility' of an op erator accidentally pulling out'th'e'raok' bar (with the. distant"main'j'swit'clrflg' closed) and firing a'reset circuit."- The'distance betweenthelever 50 and the switch 64* is-suiii'cient'topre fore the motor acts as above. Obviously whenever the current is off the rack bar can be pulled out without any difliculty but with the current on it is impossible for a firing circuit to be accidentally closed. For convenience in operation the rack bar 3i has a handle 16 pivoted as at if so that it can be turned at right angles and be received in a recess 18 in the side of the box so that the entire outer surface of the box is smooth.

It is easy to vary the time of the cycle from contact with one leaf 38 to contact with the next leaf by changing the spacing between the leaves, by changing the width of the leaves, and by selectin a desired speed of movement of the rack in its path. Up to the present moment I have found it most satisfactory when the leaves controlling the individual circuits are 5 4" wide and the space between them is and the space between the switch 64 and the arm 58 is at least double that figure. The best rack movement is obtained by having a motor with a to 1 ratio and revolving at I12 r. p. m. and drivin a pinion with 36 teeth. These figures, however, are purely for llustration and can be varied within wide limits. A very convenient way of arranging for a change in the speed of the rack is by putting shims between the motor base and the aluminum plate 29. By removing as many of these shims as desired we can use a larger pinion with the same setting of the motor and rack. While the rack could be the core of a solenoid, I have not found this arrangement very satisfactory.

Referring now to the wiring diagram Figure 6, the power terminals are numbered 80 and Si and it is understood that long wires lead from these terminals to a distant point where the operator may close the main switch 19 to operate the blast, the rack 31 at that time being drawn out as far as permitted, by the stop 45. Upon the operator closing the switch 19 current passes from the terminal 8! thru wire 82 to the motor M and by wire 83 to cut off and safety switch B l which is now closed with contact 61 touching contact 68, the current consequently flowing from the lower leaf 65 thru wire 85 to the other power terminal 80. The terminal 8| is also connected by wire 86 to the common terminal 81 and post ll of all twenty of the firing circuits, the detonators being numbered 88 in the wiring diagram and only a few being shown, the others of course being identical and each connected as by an individual wire 90 to its own leaf spring 33, the down-turned point 49 of which i engaged by the leaf 33 whenever the latter is raised, the current return being then thru wire 9i switch 64 and wire 85 to terminal 80.

Remembering first that the leaves 33 and 38 have made contact at a previous moment to fire the individual detonators and that the leaf 38 is no longer in contact with 33 then the current thru the comb 80 fiows as follows: From power terminal 80 thru wire 85 switch 64 wire 93 shaft 5i to comb 68. As this comb is depressed it engages leaves 38 and the current flows simultaneously thru all twenty of the circuits passing thru wires 90, detonators 88, to the common terminal 81 and back thru the wire 86 to the other power terminal 8|.

What I claim is:

1. A multiple hole blasting timer comprising a series of circuit switches, means to engage the switches to close and open each of them consecutively, a power line switch in the path of said means, a lever mounted in the path of the means between the series of circuit switch springs and the power line switch, and mechanism controlled by said lever for simultaneously closingrall of the switches, after all of the cirouit witches have been closed consecutively and before the current is shut oh by the power line switch.

2. A portable multiple hole blasting timer including a rigid base, a pinion, a motor secured to the base and driving said pinion, a rack bar driven by the pinion and including a cam prow, an assembly block secured to the base, a series of spring mounted on said block and all electrlcally connected together, a series of leaf springs insulated from the first series to form with the first series an alined set of switches, individual wires leading from each of the second series of springs, one member of each switch lying in the path of the rack bar so that the two leaves of each switch are successively closed.

by passage of the rack bar.

3. in an electrically fired multiple hole explosive blast, the art of avoiding the use of consumable delay devices while minimizing the: resulting earth vibration and improving the breaxage of the formation which comprises: forming paced blast holes, placing in each of these holes an explosive charge, forming a separate circuit for each of the charges including an electrical nring element in each circuit, imparting suitable electric current successively to each firing element at regular time intervals not in excess of of a second, the spacing of the holes and the time interval between successive firings being such that the burden of any charge detonated still serves as a partial burden on the next succeeding charge as it is fired.

4. The method of claim 3 in which the time interval is within the range nve to forty milliseconds, the number of circuits is at least ten and the firing current is from 50 to 600 volts.

5. A multiple hole blasting timer comprising an alined series of circuit switches, a power switch, a motor-driven means to engage the alined circuit switches so a to close and open them consecutively, mechanism operated by said means and placed so that after opening and closing all of the alined switches consecutively, the mechanism will simultaneously and momentarily close all of said circuits, and after the engaging means passes the mechanism which closes and opens all of the circuits simultaneously, the means will next open said power switch thereby shutting 01f the flow of current to the motor which drive the means.

6. A multiple hole blasting timer comprising an alined series of circuit switches, means manually movable in one direction and motor-driven in the opposite direction to engage said switches so as to open and close them consecutively, a spring-pressed cut-oif and afety switch in the path of said means and engageable by said means near the final end of its motor driven travel to overcome the spring and thus shut off current to the motor, the position of the cut-off switch with reference to the last of the series of alined switches to be opened and closed being such that when an attempt is made to manually return the means from the final end of its travel toward the initial or starting position of the means, before current is cut off from the timer, the cut-off switch will be free to close, supplying current to the driving motor before the enfli ififi gagin'gameans caniraengageesaid aalinedaswitchesin m ntingztheflmeangfromabeingmoved j from; its final? position: as long: asrthel timel} selfi isrconnectedc to the; squrce; of; power."

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