US2340695A - Explosive cartridge - Google Patents

Description

Feb; 1, 1944. J. E. ROTHROCK' EXPLOSIVE CARTRIDGE Filed Jan. 31, 1940 2 Sheets-Sheet 1 HGH JOHN E. ROTHROCK 1N VENT OR.

7 ATTORNEY.

Patented e. l, 1

EXPLQSIVE CARTRIDGE John E. Rothroclr, Newark, DeL, assignor to Hercules Powder Company, Wilmington, Belt, a

corporation of Delaware 1 Claim.

This invention relates to containers for explosives and means for initiating the explosives therein. The invention more particularly relates to a rigid plastic container for explosives and to plastic detonating charge containers for obtaining effective priming contact with and effective detonation of the explosive in the containers.

The explosive industry has for many years packaged explosives in paper cartridges or paper bags and has supplied blasting caps which are inserted into the explosive to efiect priming contact and provide a means of detonating the charge. The use of paper cartridges and blasting caps presents certain problems which are definite disadvantages. Whenever paper containers of nitroglycerin explosives are handled,

- the operators in most instances develop severe headaches which are most uncomfortable and reduce their efiiciency. The priming or inserting of blasting caps into the explosive cartridges is a dangerous job at best and one which requires skill to insure proper priming contact between the blasting cap and the explosive. Priming also must be correctly carried out to prevent separation of the cap and explosive charge when the primed cartridge is lowered into a bore hole. A further disadvantage of the paper cartridge is their lack of complete waterproofness. The increasing use of ammonium nitrate explosives makes packaging in waterproof containers essential to successful operation of present day explosives. A still further drawback to paper cartridge explosives is the poor appearance caused by their non-rigid character which is aggravated by the shipping and handling necessary before use,"'and, further, the waterproofness of paper is usually destroyed due to creasing during handling or rough treatment in the bore hole.

To overcome the various disadvantages of paper containers, the explosive industry has packaged some of the less sensitive explosives in metal cans which are completely sealed to insure waterproofness. By designing metal containers, the dangers of headaches were overcome since the operator does not contact the explosive. The waterproofing problem was also overcomeas the containers could be sealed. The waterproofing advantage was not complete; however, as the light containers may collapse under the high water pressure and leak or they may quickly rust through under conditions encountered in the bore holes.

The metal container while overcoming the headache problem presents a more serious problem in that the container itself is made of a sparking metal. The introduction of sparking metal into explosive operations creates a very hazardous condition as during the priming, loading, and tamping procedures there is always the danger of a spark struck from the container caudng a premature blast with possible damage and loss of life. In addition to sparking, the metal containers may be dangerous since they do not completely shatter or disintegrate at the time of the explosion, but may remain in large pieces and create a hazard as flying particles. The metal containers remaining after the blast, in a great many operations, have to be removed from the material as their presence may cause serious damage in subsequent operations, this removal is expensive and time consuming.

It is an object of this invention to provide a waterproof container for explosives.

An object of this invention is to provide a plastic container for explosives, adapted to be closed in a waterproof manner.

A further object of this invention is to provide a waterproof casing containing a blasting explosive.

A further object of this invention is to provide A further object of this invention is to provide a primer in combination with a guiding nose.

A further object of this invention is to provide a primer having detonating charge therein and a guiding nose attached thereto.

A further object of this invention is to provide a waterproof container for explosives which will prevent the development of headaches from the nitroglycerin explosive contained therein.

A further object of this invention is to providea rigid cartridge which will be 'easy to prime.

A further object of this invention is to provide a rigid cartridge which will completely disintegrate during the explosion.

7A still further object of this invention is to provide an explosive container and a primin device which may be joined together without aifecting the waterproofness of the explosive container.

A still further object of this invention is to provide a primed cartridge that has means whereby it may be safely and efficiently lowered into a bore hole.

Other objects of this invention will be apparent hereinafter.

In accordance with this invention, these objects have been accomplished by providing a blasting explosive container prepared from a molded plastic. This molded plastic container is provided with a closure which may be sealed thereto in a completely waterproof manner. The need of priming the explosive container has been accomplished by providing a molded plastic device in which may be positioned an initiating explosive either .directly or in the form of a blasting cap. The priming device andthe explosive container in accordance with this invention are designed so that they may be joined together in priming contact. In addition, a conical guiding nose is provided which may be attached to the leading container to aid in following the bore hole during loading operations.

The explosive containers and priming devices of this invention will be described reinafter without specifically stating that they contain explosives. However, it is to be understood that the containers described may be filled with any of the various type blasting explosives. Thus, the containers may have packed therein dynamites, extra dynamites, gelatins, extra gelatins, permissibles, or safety explosives or any other of the various explosives which are used in blastin operations. The priming devices may either contain a detonating charge in the form of a commercial blasting cap or a detonating explosive charge positioned directly in the priming device itself. The commercial blasting caps which I may use contain initial explosives such as diazodinitrophenol, lead azide, mercury fulminate, either alone or with an oxygen carrying salt such as, for example, potassium chlorate. These commercial blasting caps may also contain in conjunction with the initial explosives, secondary explosives such as tetryl, T. N. T., nitrostarch, P, E. T. N. or the like.

It is to be understood, therefore, I contemplate filling my explosive containers with any desirable blasting explosive and contemplate using in the priming devices either a commercial blasting cap or a detonating charge similar to the charges of any of the commercial blasting caps,

I or other desirable detonating charges.

Described generally, my invention comprises a tubular plastic container of blasting explosives which may be sealed to effect waterproofness and which need not be punctured for priming and which has means at one end for joining thereto a detonating device and means at the other end for, if desirable, joining a guiding nose.

aee ees embodiments thereof with reference tecompanying drawings in which Fig. l is a cross-sectional view of an assembly comprising a series of explosive containers ing a priming device connected thereto to effect detonation of the explosive and a nose positioned thereon to guide the assembly into the bore hole.

Fig. 2 is a sectional view of an individual explosive container.

Fig, 3 is a cross-sectional view of an alternative priming device for use with the explosive containers of this invention with a blasting cap located therein, and the wires thereof fastened about the priming device.

Fig. 4 is a cross-sectional view of a priming device similar to Fig. 3, but containing an additional booster charge below the blasting cap.

The casing I is open at one end and this opening contains interior threads 2 designed to receive a closure 4. The closure 4 may be cemented into position at 5 to provide a waterproof seal.

The casing I also is provided with threads 6 at the closed end for joining similar casings thereto, or for joining a substantially conical guiding nose 'I (Fig. 1) thereto. While I have shown the cartridges or casings threaded to effect joining, I may provide other telescoping or joining means such as by wedging, clamping or the like. It will be noted that Figs. 1 and 2' show the open end of the casing I slightly enlarged in order to obtain the proper joint, but while I have found this design preferable, I may prepare casings which have their open end the same diameter as the casing but which have the threaded closed end decreased in diameter to cause proper joining. Also, I may provide a tapered container to effect decrease in diameter. The threads 2 extend beyond the closure 4 in order that an additional casing may be inserted therein, Fig. 1, or so that a priming device 8, shown in Fig. 1 and also in : Eigsi 3, 4, and 5, may be easily joined to the eas- The joining together of the casings I with additional casings or with priming devices or with a guiding nose or with each is illustrated in Fig. 1. It will be noted that I have left the closure 4 in place as shown between the two casings of Fig. 1, but, if desirable, I niay remove the closure between the casing and/or between the casing and the priming device. This closure 4 is designed in a manner which insures priming and propagation of the explosive if it remains in place.

The priming devices 8 shown in Figs. 1, 3, 4, and 5 are molded plastic devices which have a central are 9 in which may be positioned a blasting cap In Fig. l the priming device. 8 comprises two parts, a holder II having a central bore 9 for the cap l0 and a cylindrical body I2 adapted to fit in locking relation by, for example, a step cut I3. Both the holder II and body I2 when joined are attached to a casing I by threads 2. The holder ii contains either slots It or holes E5 to provide means whereby the leg wires Ii 2,840,695 of the cap i@ may be extended from the holder ii. Although, I have shown both a slot It and a hole 15, I prefer to use slots since it is then unnecessary to thread the leg wires through holes. and time consuming.

In order to insure positive priming contact of the blasting cap ID with the explosive containers closure e, I may insert a plug (not shown) of rubber or other compressible material into the central bore 9. The plug may be of any desired dimensions depending on the length and type of blasting cap used.

While 'I have found the' use of a holder and body most preferable as the body prevents abrasion of the leg wires along the walls of the bore hole, I have found that I may form the holder of a diameter and with attaching means which join directly into the casings. This use of a holder by itself gives the same results as a holder and a body but there is a slight danger of abrasion of the wires along the walls of the bore hole. 7

The design of the central bore 9 of this device provides an air seal for the top of the blasting cap I!) and thus there is obtained a waterproof initiating device without the need of excess waterproofing material. Many deep hole blasting operations are carried out under as high as 900 to 1000 feet of water but the centralbore of my device is designed to provide an air pocket sufiicient to prevent the water from contacting the top of the blasting cap.

Fig. 3 shows an alternative priming device 8 in which the bottom of the cap I is substantially flush with the bottom of the device 8. This blasting cap l0 may be securely positioned by any sealing compound 2| such as sulfur, asphalt, resin, plastics, or mixtures thereof. The leg wires l6 of the blasting cap extendfrom the cap and may be, if desired, passed through the hole l5 then around the central part of the priming device 8 and through a similar hole I5 and upward from the device. This means of threading the wire l6 through the holes I5 provides a means whereby an assembled explosive casing I and priming device 8 maybe safely lowered into a bore hole. Thus, the wires are also positioned in a manner which prevents their possible I contact with the walls of the bore hole. I have found that it is also desirable in this embodiment to use slots instead of holes as stated hereinbefore. These methods I find preferable, but I may, if desirable, merely wind the wires securely about the priming device to efiect lowering of the charge. Y

An alternative means of positioning the ini- Ifnreading the leg wire is rather dificult of the central bore 9, a priming charge is superimposed on the base chargefid and a firing assembly, comprising a bridge wire 26 across the leg wires i6, positioned in contact therewith. The leg wire it is held in position by a plug 21, waterproofing material 29 and a sealing compound 2!.

The wires l8 may be threaded through slots or holes in a manner similar to that described for the priming devices of Figs. 1, 3 and. 4.

Each of the priming devices 8, Figs. 3, 4, and 5,

are similar to and act in the same way as the device 8 of Fig. 1.-

' casings which are from one-half inch to seven explosives to aid in propagation, especially of the very insensitive explosives of the "safety type. The explosives which I have used in the short lengths are, for example, high nitroglycerin powders or explosives such as tetryl, T. N. T.-or the like.

In the shipping of my explosive containers, the

priming device and the explosive container must, of course, be shipped separately, due to'I. C. C. regulations. In packing the explosive cartridges in the cases, they may be packed individually g or joined together, depending entirely upon the length ofv the cartridges, the shape and; size of the case and upon the use to which'the cartridges are to be put. In shipping the priming device, I have found that it is preferable tov either .join a priming device and a guiding nose together and ship these as a unit or to nest the guiding nose and priming device. While this is not necessary since the priming devices may be tiating charge in the priming device 8 is shown in Fig.4. The central bore 9 of this device does not extend completely through the device, but leaves a closure across the bottom 'so that a booster,

parable to the diameter of a blasting cap and then a base charge 24 is positioned in the bottom shipped aloneif the customer does not require guiding noses, the combination is the normal manner of shipping. Thus, when a priming device and a guiding nose are shipped together, the

operators have both units at hand for immediate.

and eflicient use. Further, the joining of a guiding nose and a priming device is advantageous inmoldable and when so molded to form such articles,'produce articles'which have suitable water resistance, strength, and rigidity. The various materials which are'suitable are, for example,.

the moldable plastics such as phenol-aldehyde, urea-aldehyde, wood flour phenolics and ureas, and the ligninfiber plastics, a fibrous base bound with thermoplastic lignin resins. The lig- These devices also have threads 30 about the bottom end thereof to pronin fiber has been found to be the most desirable as it is economical, waterproof, and has the necessary rigidity to withstand the usage to which it will be exposed.

A representative sample of iignin fiber plastic which I have found very desirable has the following properties:

Table Specific gravity 1.36-1.40 Specific volume cu. in. perl 19.8-2il.5 Tensile strength lbs. per sq. in- 85000-15900 Modulus of elasticity, lbs. per

sq. in. x 10 to 5th power 8-15 Compressive strength lbs. per sq. in 25,000-35,000

Flexural strength lbs. per sq. in l1,000-25,000

Impact strength ft. lbs. C. N-.. 1.5-2.0 Molding temperatures-up to 392 F C 200 Molding pressures lbs. per sq. in" 1,000-2,000 Water absorption per cent in 24 hours' 0.5-3.0

I have packed, in the casing of my invention, explosives of various types thus, for example, gelatins, dynamites, permissibles, safety explosives and variations of these types, each of which have been found to give perfect results. Al-

. though I have found those explosives which are casing may, if desirable, be directly into the caslhg or into a light paper tube which is then inserted into the casing. Either of the two methods give excellent results and the preferable method depends entirely upon the type machinery to be used and the type explosive being packed. In packing of high nitroglycerin explosives, I prefer to use a paper liner in the casing to aid in preventing segregation of the nitroglycerin, while in safety and permissible explosives, I prefer to pack the explosive directly into the casing. I have found that packing in the casing to a predetermined density is facilirated by the rigid character or my casing and that bulging which is often encountered in paper cartridges is never experienced.

The closures which I use for the casing of this invention are usually made from the same type plastic as the casing and are threaded. Upon screwing the closure into place, a suitable waterproofing material is used to make awaterproof Joint.

The advantages of my plastic casings and primer devices, are that explosives may be packed in entirely waterproof packages which may be primed without the need of puncturing the container. The explosive is packed in a rigid container which is neat, easy to handle, and which prevents operators from contracting headaches. There is altering of sensitiveness due to water or high pressures encountered in bore holes. The use of the primer device insures positive priming and due to the arrangement of the wires provides a method of lowering explosives into the bore hole which prevents the danger of separating the primer from the explosive encountered in the prior art.

Where in the specification and claims, I have used the term plastic as, for example, a plastic casing, it is to be understood that I have used the term in the sense it is used in the molding art. Thus, the term plastic refers to organic moldable or molded materials which'may be, for example, of the thermosetting or thermoplastic type.

It will be understood that the details'and examples hereinbefcre set forth are illustrative only, and that the invention as broadly described and claimed is in no way limited thereby.

What I claim and desire to protect by Letters Patent is:

In combination a primed blasting assembly including a priming device and an explosive cartridge, said cartridge being made of a synthetic plastic molding material, attaching means adjacent one end of said cartridge, means closing said cartridge against the entrance of moisture, said priming device being secured to said attaching means and comprising a detonator receiving chamber having an open end adjacent the cartridge closure means and having a closed end whereby air may be trapped in said chamber to prevent the entrance of water thereto, a detonator-leg-wire-opening in said device, said opening extending into the chamber adjacent the open end of said device.

1 JOHN E. ROTHROCK.

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