US2089981A - Blasting apparatus - Google Patents

Description

Aug. 17,1937. R. PRICE BLASTING APPARATUS Filed Jan. 17, 1936 2 Sheets-Sheet 1 Aug. 17, 1937. R p E 2,089,981

BLASTING APPARATUS Filed Jan. 17, 1936 2 Sheets-Sheet 2 2665 F311]. floss/qr PRICE Patented Aug. 17, 1937 UNI-TED STATES PATENT OFFICE 6 Claims.

The invention relates to blasting apparatus designed primarily for use in firing blasting charges within mines, although the invention is not restricted to this particular field of use.

A twin-wire charge-firing cable is wound on a reel within asuitable hand-carried casing, and a charge-firing switch is provided for connecting said cable with a source of current (battery or magneto) to complete the firing circuit, and the principal object of the invention is to prevent closing of said charge-firing switch until such a length of the cable has been unwound from the reel (by carrying the casing away from the charge) as to insure the safety of the person carrying said casing, against injury from the blast.

For safety, it has long been required that the ends of the two wires of the blasting cable remote from the cap-engaging end of said cable,

0 be conductively connected with each other before connecting said wires with the cap, and a further object of the invention is to prdvide a normally closed safety switch for this purpose, which cannot be opened until the aforesaid length of cable has been unwound from the reel.

Yet another object is toprovide an apparatus in which closing of the firing switch effects opening of the aforesaid safety switch.

A still further object is to provide an arrangement of indicating numbers which will show to mine inspectors the exact number of feet of cable connected with the reel. Thus, without measuring, an inspector may determine whether the cable is as long as required or whether it has been shortened, due for instance, to injury, splicing,

etc.

With the foregoing and minor objects in view, the invention resides in the novel subject matter hereinafter described and claimed, description being accomplished by reference to the accompanying drawings.

Fig. 1 is a side elevation.

Fig. 2 is an edge view with the blasting cable partially unwound from the reel.

Fig. 3 is arr enlarged vertical sectional view on line 3--3 of Fig. 1.

Fig. 4 is an enlarged elevation showing the switch and its locking means in the positions which they occupy while the firing cable is wound 'upon the reel.

Fig. 5 is a view similar to Fig. 4 but illustrating the switch-locking means in released position.

Fig. 6 is an elevation of the switch base and its load terminals or contacts, the rotatable switch member and the switch cap being removed.

Fig. 7 is an inner side elevation of the cap and switch member.

Fig. 8 is an inner side elevation of the switch cap.

Fig. 9 is an elevation of the rotatable switch member.

Fig. 10 is a sectional view through the assembled switch substantially on line l0l0 of Fig. 6.

Fig. 11 is a detail sectional view on line n of Fig. 6. I

The form of construction selected for illustration in the present application will be rather specifically described, with the understanding however, that within the scope of the invention as claimed, numerous variations may be made.

A casing I2 is provided containing a reel I3 for a twin-wire charge-firing cable I4, the end of this cable which is adapted for connection with the cap, being preferably provided with a flexible metallic armor l5 to prevent injury thereto when a blast is fired.

One side of the reel I3 is provided with two contact rings l6 and I! which are insulated therefrom, and one side of the casing l2 carries two contact rings l8 and i9, these rings being insulated from the casing and being disposed in contact with said rings it and i1 respectively. One of the wires 20 of the cable i4 is connected with the ring I6 and the other wire 2| of said cable is connected with the ring ii. A wire 22 is connected with the ring i8 and a wire 23 is connected with the ring i9, said wires 22 and 23 leading to the exterior of the casing l2 and to a switch 24. Two leads 25 and 26 extend to this switch from a battery 21 or some other desired source of current. connects the leads 25 and 28 from the wires 22 and 23 and conductively connects these two wires 22 and 23 with each other. Since these wires 22 and 23 are connected conductively with the two wires 20 and 21 of the cable l4, these wires 2!! and 2i are thus conductively connected with each other in accordance with safety requirements. When the switch 24 is actuated to conductively connect the lead 25 with the wire 22 and the lead 26 with the wire 23, said switch disconnects the Wires 22 and 23 from each other so that the blasting circuit is completed. Features of switch construction preferably used in producing the desired operation, will be hereinafter explained, but it may here be stated that the switch dis- Normally,,the switch 24 disclosed is of a rotatable type and includes an actuating shaft 28. Novel provision is made for so holding this shaft as to prevent operation of the switch 24 to fire a charge, until-a predeterg mined length of the cable M has been unwound a head 29 having a socket 30 into which a key K may be inserted to turn the head and shaft when rotation of said shaft is permitted by predetermined rotation of the reel I3, .as hereinafter explained. A spring-pressed plunger 3! (Fig. mounted in a suitable fixed plate or the like 32, is preferably received in a portion of the key socket 30 to prevent any possible accidental movement of the switch, said plunger 31 however, being releasable by insertion of the key. A spring 33 is preferably provided to eject the key from the socket 30 when the switch has been restored to its normal position, and in order that said switch cannot remain in firing position, a spring 34 is connected with the head 29, it being necessary to hold the switch in firing pos'ition against-the tension of this spring, with the result that the spring will again open the switch, and as soon as the switch reaches this normal open position, the plunger 3| locks it and the spring 33 ejects the key.

Operation of the switch bygmeans of the key is normally prevented by novel mechanism releasable only by predetermined rotation of the reel l3. A locking disk 35 is mounted on a shaft 36 parallel with the switch shaft 28 and the reel shaft 31, the head 29'on said switch shaft bee ing provided with a curved edge '38 which en- 9 gages the edge of said locking disk 35 (Fig. 4)

until said disk as has rotated sufficiently to bring a notch 39 with which its edge is provided, opposite said head 29 (Fig. 5). The head 29 may (Fig. 3) and by having said nuts positioned within the cover 23. k

Normally, the switch stands in the position at which it disconnects the cable M from the source of current 21 an connects the two wires 20 and 2! of said cable onductively with each other. said switch being held in this position by contact of the edge 38 of the head 29 with the lockthen be turned by insertion of the key to actuate the switch. The disk 35 is driven by a train of speed reduction gearing from the reel shaft 31 and it, will thus be seen that said disk will allow operation of the switch to effect charge firing, only when the reel has been rotated to a pre- 50 determined extent by unwinding of the chargefiring cable l4 therefrom.

In the present showing, the reel shaft 31 is provided with a worm d0 meshing with a worm 5 gear 4| on a transverse shaft 42, this-shaft being provided with a worm 43 meshing with a worm gear I on the shaft 36 of the disk 35. Other gearing however, could of course be employed to cause the reel l3 to drive the switch-locking disk 35. Asuitable yoke 45 has been shown to assist in properly mounting the shaft 36 and possibly other parts upon the exterior of the casing l2, and the plate or the like 32 above described, may well be; secured to this yoke.

A hinged cover 46 is preferably provided to contain the switch 24, the driving gearing for the locking member 35, the locking member itself,

the battery 21 and a number of the wires, said cover being held in closed position by suitable locking or sealing means 41 to prevent tamper- 7 ing with any parts confined within said cover,

Tampering with the reel or other parts withinl the casing l2, may be prevented by so constructing the casing that access to its interior cannot be had without removing nuts 43 from bolts 9 ing disk 35 as seen in Fig. 4. With the switch thus held, the cable I4 is connected with 'the charge to be fired. The casing I2 is then carried, by means of a suitable handle 50', away from the charge, causingunwinding of the cable II from the reel l3. By the time 'a predetermined amount of this cable has been unwound from the reel, this reel has caused the gearing 40, ll, 43 and M to drive the disk 35 to the position shown in Fig. 5. The switch may then be operated by means of thekey, which;v key is passed through a suitable key-hole 5| in the cover 46. When the key is inserted, it releases the tumbler or plunger 3| and by means of the key, the switch may then .be operated to cause disconnection of the wires 20 and 2| from each other and to conductively connect these wires with the current source 21, causing firing of the charge. When pressure on the key is released, the spring 34 restores the switch to its normal position and the spring 33 ejects-the key. The cable I! is then rewound upon the reel l3 by turning the hand crank 52, the charge having been fired. During this rewinding, the locking disk 35 returns to its original position? Rewinding of the cable by rotating thereel l3 in the improper direction, may be prevented by providing this locking disk with a stop 53 which will strike the knob 29 as seen in Fig. 5.

I preferably provide an arcuate series of numbers on the locking disk 35 as denoted at 5| in Figs. 4 and-5, said numbers being successively visible through a view opening 55 in the cover- 48 as said locking disk rotates. The numbers represent units of measurement, preferably feetand they range, from zero to the maximum number of feet of cable ll which the device is to carry. When the cable is entirely unwound from the reel or unwound as far as possible, zero appears in the opening 55 indicating that there is then practically. no cable upon the reel. If

twenty feet of cable be returned into the casingi2, 20 will appearin the opening 55, etc. Thus, if the cable should be say-one hundred and ten feet long, "110 will appearin the opening 55 when the cableis fully wound on the reel and a mine inspector seeing this, would know that the cable was of the required length. If he inspected the device with the cable fully wound and found that-'l00" instead of 110" appeared in the opening 55, he would know that the cable had been shortened ten feet and the device would therefore be rejected instead of passed,

until the deficiency had been corrected. 2

The switch 24 in the present disclosure, in-

cludes a'base 51, a cap '53 and a rotatable switch member 59 between said cap and base. The cap and base are secured together by any suitable means and the entire switch is mounted in any preferred manner, and the switch member 59 is keyed to or otherwise connected with the shaft.

23 to be rotated by the latter. The base 51 carries two load terminals or contacts BI and 32 which are connected with the wires 22 and 23 respectively. The cap' 58 carries two lead terminals or contacts and. which are connected with the wires 25 and 26 respectively. The switch member 59 carries two contacts'65 and 66 located at one side only thereof, said contacts being connected by a conductor 61. When the switch is in its normal position, contact 65 lies against the terminal or contact 6 and contact '66 similarly engages the terminal or contact 62. Thus,

by means of 6|, 65, 61, 66 and 62, the wire 22 is conductively connected with the wire 23, for 10 safety.

The switch member 59 carries two other contacts 68 and 68 which extend entirely therethrough. when this switch member is rotated by the key, contact 68 engages the contact 6| and the contact 63, and contact 69 engages the contact 62 and the contact 64. Thus current may fiow from wire 25 through 63, 68 and 6| to wire 22 and current can fiow from wire 26 through 64, 69 and 62 to wire 23, completing the firing circuit.

I prefer to mount spring-pressed insulating buttons 10 in the terminals or contacts 6|, 62, 63 and 64 preventing the contacts 68 and 69 from engaging said terminals or contacts unless the switch member 59 is forcibly turned. Thus, should any unusual occurrence free the switch member 59 from the locking means, the firing circuit could not be completed by accidental rotation of said switch member.

From the foregoing, it will be seen that novel provision has been made for carrying out the objects of the invention but attention is again in vited to the possibility of making numerous variations over the construction herein disclosed.

I claim:

1. A blasting apparatus comprising a reel, a current-conducting charge-firing cable securedto and wound on said reel, normally open chargefiring contact means for connecting said cable with a source of current when closed, additional normally closed contact means for conductively connecting the two conductors of said firing cable with each other until the charge is to be fired, and reel-driven control means for both of said contact means constraining them to remain in their normal positions until said reel has rotated sufiiciently to pay out a predetermined length of said cable and for then freeing said contact means to permit actuation thereof.

2. A blasting apparatus comprising a reel, a current-conducting charge-firing cable secured to and wound on said reel, normally open chargefiring contact means for connecting said cable with a source of current when closed, and addi- 55 tional normally closed contact means for conductively connecting the two conductors of said firing cable with each other until the charge is to be fired, locking means for both of said contact means operatively connected with said reel,

60 and reel-driven means for releasing said locking means only when said reel has been rotated to a predetermined extent.

3. A blasting apparatus comprising a reel, a current-conducting charge-firing cable secured to 65 and wound on said reel, normally open chargefiring contact means, controlling means for said charge-firing contact means active to hold the same open until said reel has been rotated to a predetermined extent and to then free said 70 charge-firing contact means for operation, said charge-firing contact means being connected with said cable and with a source or current to complete the charge-firing circuit when closed, and normally closed contact means operatively connected with said charge-firing contact means and movable to open position by closing of said charge-firing contact means, said normally closed contact means being so connected with the two conductors of the charge-firing cable as to conductively connect said conductors with each other prior to opening of said normally closed contact means.

4. A blasting apparatus comprising a currentconducting charge-firing cable for connection with a charge to be fired, a reel upon which said cable is wound, a carrier for said reel by means of which the blaster carries said reel away from the charge to unwind the cable after connecting said cable with said charge, a switch for completing 'the charge-firing circuit, andmeans actuated by the cable-unwinding operation for preventing closing of said switch until said reel has rotated sufiiciently to pay out a length of cable long enough to reach a safe distance from the charge, and for freeing said switch for operation when said reel has rotated to said extent, whereby if the blaster has unwound said length of cable by carrying said carrier away from the charge, he will be at a safe distance from said charge when said switch means is freed for operation.

5. A blasting apparatus comprising a chargefiring current-conducting cable for connection with a charge to be fired, a reel upon which said cable is wound, a carrier for said reel by means of which the blaster carries said reel away from the charge to unwind the cable after connecting said cable with said charge, a switch for completing the charge-firing circuit, a movably mounted locking member for holding said switch open until said locking member has been moved to a predetermined released position, and means driven by said reel for disposing said locking member at said released position only when said reel has rotated suificiently to pay out a length of cable long enough to reach a safe distance from the charge, whereby if the blaster has unwound said length of cable by carrying said carrier away from the charge, he will be at a safe distance from said charge when said locking member reaches said released position.

6. A blasting apparatus comprising a currentconducting charge-firing cable for connection with a charge to be fired, a reel upon which said cable is wound, a carrier for said reel by means of which the blaster carries said reel away from the charge to unwind the cable after connecting said cable with said charge, a switch for completing the charge-firing circuit, a rotatable looking member mounted on said carrier and operatively associated with said switch for holding said switch open until said locking member has been rotated to a predetermined released position, and reduction gearing operatively connecting said locking member with said reel for slowly rotating said locking member toward said released position as the reel is rotated during carrying away from the charge, said gearing being such as to dispose said locking member at said released position only when said reel has rotated suificiently to pay out a length of cable long enough to reach a safe distance from the charge, whereby if the blaster has unwound said length of cable by carrying said carrier away from the charge, he will be at a safe distance from said charge when said locking member reaches said released position.

ROBERT PRICE.

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