US2115388A - Safety blasting plug - Google Patents

Description

April 1938- I J. HElTZMAN 2,115,388

SAFETY BLASTING PLUG Filed Oct. 8, 1934 2 Sheets -Sheet 1 RICHARD J HITZMflN April 1938- R. J. HEITZMAN 2,115,388

SAFETY BLASTING PLUG Filed 001:. 8 1934 2 Sheets-Sheet 2 R ICHARD (I HE/Tz MAN l atented Apr. 26, 1Si38 Q um'rsn .sm'rss PATENT SAFETY BLAST1NG. PLUG Richard J. lieitzm'am, Shamokin, Pa., assignor or one-fourth to William E. Ressler, Shamokin, Pa.

Application October 8, 1934, Serial Nat-11435 -4 Claims. '(Cl. 102-11) This invention relates to; blasting plugs and is of which the same characters of reference have an improvement upon the type of blasting plug been employed to denote identical parts: :described'and claimed in my Patent No. 1,896,817. Figure 1 is a longitudinal section through a I granted February '7 1933. The present improvebore hole showing one form of my improved ment as wellas: the blasting plug forming. the blasting plug in position with respect to the dysubject. matter of said patent is particularly em-' namite and the sand packing; ployed in mining and quarrying and has for its Figure 2 is a perspective view of the blasting general object to increase the safety factor of plug'shown in Figure 1; v e such devices by avoidingthos'e causes of misfire Figure 3 is an end elevation;

ordinarily attributable to short circuiting, and Figure 4 is a perspective view of a cylindrical 10 should a misflre occur through inherentdefect sponge rubber blasting plug;

in the detonating cap, the invention affords a safe Figure 5 is a perspective view partly in secmeans for the extraction ofthe detonatingicap tion through a cylindrical soft rubber plug havirom the bore hole. ing a single wire slot extending throughout the '15 The characteristic features of the invention length thereof; covered in the patent aforementioned are the Figures 6 and 7 are respectively a perspective absence of metal in the construction of the blastview and end elevation of a cylindrical soft blasting plug and the provision of an expansible anteing plug having'two wire slots; i r or portion which under the tamping pressure Figures Band 9 are similar views showing spreads to conform to the wall of the bore hole another form of. the invention in which the blast- I in a firm and gas-tight manner, the rear portion 'in'g plug is of relatively hard material and. probeing of such nature as to be readily penetrated videdwith asingle wire slot; byan auger for the purpose-of effecting the with-- Figures 10 and 11 are similar views showing a drawal of the plug in the event of a mis'flre." Since plug of hard rubber or its equivalent having two short circuiting is ordinarily caused by abrasion .late'ral wire slots; 25

. of one of the wires leading to the detonating cap- Figure 12 is a perspective view of a hard blastincident to the friction of tamping, the invention ing plug having no provisions for the wires; of the patent safeguards the wires by providing Figure 13' is an end elevation of the same; I i a separate bores in the plug through which the Figures 14 and 15 are respectively a perspec- *"3oW e p y. threaded, keeping them tive view and end elevation of a composite plug 1 .apart from one another and away from the wall havingthe anterior portionsoit and the posterior of the bore hole. a portion hard with a single wire slot extending In practice however'it has been found at times through the hard portion only; and somewhat dificult to thread the wires through Figures 16 and 1'7 are similar views showing the the bore holes on account or insufficient illuminacomposite plug with the wire slot extending tion in the mine or the ravelled nature of the through both the hard and soft portions. insulation of the wire at its free ends. The pres- Referring now in detail to the several figures ent invention thereforehas for its speciiicoband first adverting to that form of the invenject the provision of lateral slots into which the tion shown in Figures 1,; 2.and 3, the numeral 40 wire may be pressed and retained, on operation i represents a plug preferably of conical form 40 which can be performed bythe sense of feeling throughout its anterior portion, and having a alone and which can bedoneif need be in the cylindrical zone 2 at its posterior end, with an dark. a Y

intermediate taper 3. The entire plug is pref- .Another object of the invention is to makethe erably made of a softcompressible material such' i blasting plug of such yielding material that even as sponge rubber which material has not only the :45 i n in the absence of 'any bore for receiving the wires advantage of inherent softness, but also has'lmv the same may be placed alongside the plug in -prisoned air bodies which assist. in cushioning customary manner-as .itis inserted in the bore the impact of the explosion. A lateral slot 6 for hole and theplug will yield to the shapeof the receiving the ignition wires is formed in the 5g givireishas it is tamped into place, without abradcylindrical z'onev and opens into the tapered por- 5(1 .ng em.

tion 3. Figure 3 shows that the slot may'consist Other objects ofjlthe invention will appearas of a tubular recess opening to the exterior plug the following. description of a number of 'em- .by amerefsliti which'spreads to admit the wires bodiments of the invention proceeds. and then springs back into closed position so i In thedrawings thijoughout the several figures that the slot 4 completely encompasses the wires 55 tendency to abrade' t the plug by means of shielding them from coming in contact with the wall of the bore hole. The posterior end of the cylindrical zone is preferably concaved to guide the tamping rod or ram so' as to avoid its corning in contact with the wires at'their point of emergence from the plug at which point they are close together and special precaution must be taken to prevent the insulation becoming dam- In practice, the sticks 'of dynamite 6 having been put in place in the bore hole with the detonating cap J embedded in the last stick and. the wires 8 and {leading therefrom to the exterior of the bore hole, the safety plug is taken and, the two wires 8 and 9 pressed through the slit 5 into theslot 4.. The blasting plug is then thrust into the bore hole and slid along. the wires under the pressure of theram or tamper until its anterior end comes adjacent the final stick of dynamite. Further action of the tamper or ram causes the soft rubber to expand radially filling the bore hole and coming into intimate and sealing relation with the wall of the bore hole. The enlarged cylindrical portion of the blasting plug forms a-tightseal against the wall of the bore hole preventing the escape of gases until the explosion has expended its force.

In view of the fact that the portion I is conical, it does not come into intimate contact with the wires until the blasting plug has been pushed entirely into place. Consequently, there is no e wires against the wall of the bore hole.

If a misfire occurs it is an easy matter to insert an anger, boring into the posterior portion of the blasting plug and to draw it out without the risk of sparks which might cause an explgsi on.

In Figure 4 a form of the invention is shown in which the blasting plug I0 is an. undiflferenti'ated cylinder of soft material such as sponge rubber, no slots being provided for the, protection. of the wires. This cylinder is pushed into the. bore hole with the tamper, its-yielding nature; causing it to conform to the wires'as it is pushed in. When it is in final position, a few blows with the tamper expand it radially'and retain it in place.- v f Figure '5' is a blasting plug ll of similar shape andmaterial, but in this instance a slot 4 ex' tends longitudinally therethrough and opens in the lateral surface of the plug by means of they slit- 5 which closes. after the wires have been pushed in. The manner of inserting this plug is l the same as in the previously described modifi- I a cation. '1.

In those forms of the invention which have been described up to the present time, both wires. .3 are introduced into the same slot. "Figures -6 and 7 show a further modificatmn of theinvention' in which the wires are independently inserted in different slots. The cylindrical plug I2 is of soft material, having a pair of similar bores II and. t4 extending therethrough in parallel relation i and communicating with the lateral surface or slits l5 and. I8. One of the ignition wires ispressed into ,each slot just before'the plug is introduced in thebore hole. Figures 8, 9, 10 and 11 are respectiv l per? spective views and views in-end elevation of two forms of plug which are a departure of those forms previously described inasmuch as they are of hard material throughout. 'I'heplug l1 shownall M m' Figure-8 is provided with a singl'eopen groove peripheral position .of

' of the ignition wires.

rialsuch as -.tion 24 soft anterior portion 21 and ignition wires.

ing into the lateral surface of said body by means of a yieldthe diametrical, dimension l8 for the reception of the two ignition .wires whereby when the plug is driven into placethe wires are protected-from being'abraded against the wall of the bore hole. In this form of the invention no provision is made for sealing the 5 plug in the gas-tight manner its sole claim to patentability being in protecting the wires. It

is also characterized by being non-metallic and the posterior end is readily penetrable by an auger for removing the plug: On account of the w the wires there is no risk of the auger boring into the wires. v The plug l9 shown in Figure 10 is similar to that shown in Figure excepting'that there aretwo longitudinal grooves 20 and 2|, one for each 15 Figures 12 and 13 show a hard rubber plug of and having no provision for safeguarding the ignition wires. It is readily removable by'means of an auger of producing a spark;

' Figure 14 shows a composite blasting plug having the anterior portion ZSformed of soft matesponge rubber and the posterior porbeing-made. of hard material such for 245 example as hard rubber. The hard portion-has an open groove 25 extending, therethrough, but the soft portion is devoid of any such groove. The wires are introduced laterally into the groove 2! be of the portion which extend from the groove II. Figure 16 shows a composite plug 26 having a" portion Hi In this instance-both portions are provided with an open slot extending longltudinally therethrough and-adapted toreceive the While I have in the above description defined 40 extending longitudinally therethrough and openlateral surface of said plug, the posterior end of said plug being concave;

ing-walled narrow slit. 3. Safety blasting plug. comprising a bodyof yielding rubber having. a longitudlnal'bore ex-" tendingtherethrough communicating with the lateral surface of said body by means of a yield-. ing-walled slit of'such-normal width'dimension gg asto retain iufsaidborea wire forced through said'slit. a w '4. Safety blasting plug comprising a body of yielding rubber having l a longitudinal bore extending therethrough communicating with ing walled sun said slit being of less width than totretain in said borea wiretforccd through said a hard posterior 35

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