US2654285A - Borehole loader - Google Patents

Description

Patented Oct. 6, 1953 BOREHOLE LOADER RobertMcGirr, Pottsville, Pa., assignorto Atlas Powder Company, Wilmington, Del., 1: corporation of Delaware,

Application August 31, 1948,, Serial No. 47,062

5 Claims.

The present invention relatesto a novel device for loading and compacting explosivecharges into'the bore hole in blasting operations. More particularly, the'invention relates to such a device, commonly called a bore hole loader which is flexibleand thus adapted for many operations wherethe useof conventional bore hole loaders iseitlier exceedingly difficult or impossible.

In blasting'operations, holes are bored into the material to be blasted, such as coal, ore, limestone, rock, earth and the like. The depth of the holes varies widely, depending upon the particular operation, but in many cases the holes may even reach a depth of 200' feet. The explosive, generally in the formof a paper-wrapped cartridge, is inserted into the hole and pushed to the farend-by the bore hole loader. Numerous cartridges, the exact number varying depending uponthe particular-operation, are often inserted into each hole.

Itis generally desirable to compact the explosive in the end' of the bore hole and this is usually accomplished by tamping the inserted cartridges with the-bore hole loader. The cartridges collapse under'the tampingpressureand form a relatively compact mass in the far end or the bore hole. When very long bore holes are employed, theinsertion of the cartridgesfa's well as thetamping thereof, is difiicult and this is especially so, Whenthe blasting; operation is being: carried out me mine where working space is limited. Heretoiore',. long sticks; poles: or pipes haveib'een employed as the bore hole'loader when blasting was being carried out in the open or wherever there wasisufiicient working space: to accommodate the long articles. Such long sticks or; pipes, however; cannot: be conveniently transportedifrom plane: to: place: As a consequence of and:sinceiinminesinsuflicientiworkingspace available for using long sticks, poles, or" pipes; jointed-sticks and attachable pipe-sections have come into use. Since, however, only aifew car;- tridges can be inserted and tamped at: a. time; the loading of one hole. often necessitates. dis."- sembling and-reassembling the stick or pipe sections. many times. Obviously this is a tedious and. time-consuming operation.

The principalobjectof the presentinvention is to provide a novel bore hole loader which obviates the objections and disadvantages of prior loaders as above mentioned.

A more specific object of the present invention is'to provide a novel bore hole loader comprising'a long element'which is flexible enough to be'bent' in" confined spaces.

A further object is to provide a bore hole loaderwhich is sufficiently flexible to be wound in-a coil or a drum for easy transportation and storage.

A further object is'to provide'a novel bore hole loaderwhich, whilefiexible as above set forth, is sufliciently rigid to transmit tamping pressure against" the inserted explosive cartridges even in the deepest of 'bore' holes.

Further objects, will be apparent from a consideration of the following specification and claims;

The borehole loader of the present invention comprises an elongate core of flexible spring metal, preferably of substantially circular crosssection, a covering or sheath therefor of tough, flexible, non-sparking material, and a tamping head portion of tough, hard, non-sparking material rigidly attachedto one end, namely tamping end, of the oore'an'd sheath assembly. By nonsparking material is'meant a material which will not producea spark when struck on another hard surface such as rock. The sheath member is of substantiallythe" same length as the core member and-covers and insulates the core from con tact with the sides of thebore hole. In the preferred embodiment of theinvention, the-tamping head is connected to the core and sheath assembly'by means of an intermediary member of a non-sparking material. In this case, the intermediary member is securely attached to the core so'that a relatively short length of the nonsparking intermediary member extendsfrom the sheath, and the tamping head is attached to this extended portion.

In the accompanying drawings:

Figure 1 is a longitudinal sectional view of the tamping end of one embodiment of the device of the present invention;

Figure 2 is a longitudinal sectional view of the tamping end of the device of the preferred embodiment of the present invention;

Figure 3'is a diagrammatic view partlyin-section illustrating one manner of the application of the device of the present invention in loading and tamping an explosive charge in a bore hole; and

Figure 4 is an elevational view of the apparatus shown in Figure 3 as viewed from the left.

Referring more specifically to Figures 1 and 2, l I represents the core member, l2 the sheath member and 13 the tamping head. In Figure 2, l4 represents the intermediate length of nonsparking material to which both the core member and the tamping head are attached. As indicated above, these figures represent difierent embodiments of the invention, Figure 2 being the preferred embodiment. These figures will be described in greater detail hereinafter.

The core is, as stated, of iiexible sprin metal. The metal in the core is in the form of wire, the term wire being used in the broad sense to denote metal drawn out to a relatively small diameter of generally less than about .5". The particular core diameter employed will be deter mined in part by the degree of flexibility required by the nature of the location of the blasting operation. In mines for example, where numerous sharp bends and confinement of working space require sharp bends or even coiling of the loader, the use of a wire core of relatively small diameter, such as about .31", is recommended. On the other hand, on operations where there is little or no space restriction, a larger size wire core may be employed. The most well known and easily available spring metal in wire form is spring steel wire, and this is the material preferably employed. as the core. Therefore, the invention will be described with reference to a steel wire core, although it will be understood that any other spring metal having elasticity properties comparable to spring steel wire may be employed. Spring steel wire generally ranges in diameter from 0.49" at the maximum down to very fine piano wire. The diameter of the core of the bore hole loader of the present invention, however, should generally not be less than about 1%". Although it is preferred that the core be of one solid wire, it may be made up of a plurality of wires, in which case wires of finer diameter may be employed so long as the average core diameter provided by the plurality of wires is of the order above stated.

The function of the spring metal core is at least twofold. It imparts sufficient rigidity to the device so that a thrusting force exerted at one end is transmitted to the other end to exert a tamping force on the explosive cartridges. In this case, the spring steel core prevents collapsing or buckling of the device even when tamping the explosive cartridge in a very deep bore hole. In addition, the spring steel core prevents objectionable kinks and bends from occurring in the device during handling, transportation or storage. Thus, while the device is sufficiently' flexible to be bent in confined spaces, or to be wound, it is sufficiently resilient to assume its rod-like shape after any distorting force has been removed.

The sheath member encasing the core may be of any tough, flexible non-sparking material. It should be flexible in the sense that it should be cap-able of bending as freely as the core it encases and, when surrounding the core, it should not hinder the flexibility of the core member appreciably. Since tools used, in blasting operations ordinarily encounter rough treatment, the sheath material should be sufficiently tough to resist abrasion and other wear and to withstand sharp or jagged surfaces. Ordinary rubber hose, with or without cloth or metal fabric reinforcement of the type used in various types of heavy equipment such as pneumatic hammers and the like, is suitable. Synthetic rubber, such as for exam ple neoprene, with or without a fabric reinforcement, serves equally as Well as the sheath material. Other compositions containing natural or synthetic rubber, or both, or synthetic plastics, may also be employed.

The sheath may be prepared separately, for

charged with explosives.

instance in the form of a tube or hose after which the core member is inserted. Alternatively, the material from which the sheath member is to be made may be directly applied to the core member, such as by extruding a rubber or plastic composition around the core and allowing it to set. It is not necessary that the sheath fit the core snugly, for example, when the sheath is a standard hose and the core a standard steel spring wire, the hose will often fit somewhat loosely since conventional hose sizes and steel wire sizes do not agree in many cases.

The sheath has several functions in the device of the present invention. In the first place, since steel is a sparking metal, its presence, when exposed, is dangerous in mines and in bore holes The sheath member. therefore, serves to completely insulate the core member and thus to prevent explosions due to sparking. In the second place, the sheath protests the core from moisture and other corrosive materials present in mines and other blasting sites. In addition, the sheath adds greater body to the device without sacrificing flexibility.

The tamping head, rigidly attached to the core and sheath assembly and attached either directly or indirectly to the core member, may be any hard, tough, non-sparking material. As stated, by non-sparking material is meant a material which will not produce a spark when struck on another hard surface such as rock. A wide variety of materials may be used for this purpose, such as for example, wood, synthetic plastics such as molded phenol-formaldehyde and urea-formaldehyde resins, molded hard synthetic rubbers and compositions containing them, hard rubber and rubber-containing compositions, non-sparking metals such as brass, and the like. Especially useful is the thermosetting phenol-formaldehyde resin composition known as Bakelite.

Referring more particularly to the drawings, it will be noted that in Figure 1 the core ll extends into the tamping head I3. The method of securing these two members will depend somewhat upon the type of material from which the tamping head is made. For example, if the tamping head is of a non-sparking metal, such as brass, it may be sweated onto the core member, or it may be threaded on or even cemented in place. If the tamping head is of a non-metallic material it may be either threaded or cemented on. The sheath member I2 is secured to the core or the tamping head, or both, by appropriate means (as by cement) to prevent the sheath from pulling away and exposing the core.

Figure 2, representing the preferred embodiment of the invention, illustrates a convenient means of insuring no exposure of the core member while at the same time, if desired, providing a bore hole loader with an easily replaceable tamping head. The intermediate length of nonsparking material [4, is advantageously a nonsparking metal such as brass, although any hard material such as those mentioned previously with reference to the tamping head, may be employed. The intermediate portion 14 is advantageously more or less permanently secured to the core member as by cementing or, if a non-sparking metal, by sweating. The sheath extends beyond the end of the core, while the intermediate section [4 protrudes somewhat beyond the end of the sheath. The tamping head is then secured by any suitable means, such as by threadcementing or sweating, to the protruding 'illqrtion of {the *intermediate "section. fAiivantameasly. the "protruding -portion 'of the intergmeiiiate "section is provided "with a thread, as i'illnstrated "in Fig. 2, "to "enable iconvenient freiplaicementofth'e -tamping'head. :In thisembodi- :ment, .the sheath I2 is "cemented firmly *to :the umdei'lying portion "of the intermediate section.

Asillustrated'in the figures, v:the tamping Ihead is advantageously slightly smaller in diameter than the cartridge to be tamped, although tamping heads larger in diameter may be used if de sired. As is also illustrated, the tamping head is advantageously beveled at its leading and trailing edges l5 and It, to facilitate its movement through the bore hole. The leading face I! of the tamping head is flat to serve as the tamping surface. The bore hole loader of the invention may be supplied with interchangeable tamping heads of different sizes for use with cartridges of different diameters.

While only one end of the bore hole loader is illustrated in the figures, it will be understood that the other end may be capped or otherwise sealed off in any convenient manner. It is often preferable, however, to provide each end of the bore hole loader with a tamping head of the type described so that either end of the device is available for use. In any event, the core and sheath arrangement illustrated is employed. It is often desirable to provide indicia of length on the bore hole loaders of the invention. In this way it is easy to tell how far a given charge has been tamped into a bore hole. The length of the device, of course, may vary widely, depending upon the operations intended to be served by it, for instance, the overall length may even reach 200 feet or more. However, it is not necessary that the core and sheath assembly be continuous throughout its length since provisions can easily be made for temporarily attaching an added length or lengths of core and sheath assembly if the operation requires it. For example, in a particular mine where the length of loader required for usual bore hole does not generally exceed say 25 feet but where, on occasion, a length of about 200 feet in depth may be required, it would be somewhat inconvenient to employ a bore hole loader of over 200 feet in length for the shorter bore holes. In such circumstances, it is more feasible to provide the bore hole loader in attachable sections, the tamping end portion being about the length required for the usual bore holes but being easily attachable to an added core and sheath section or sections to provide a bore hole loader having the required length for the occasional deeper bore holes. There are a wide variety of means for temporarily attaching such core and sheath assemblies together, such as, for example, by clamping, pin-joints, unions, coupling, and the like, care being taken not to expose sparking materials.

The device of the present invention may be operated manually or with the aid of a machine. Figures 3 and 4 illustrate a mechanical method used in loading bore holes when wooden poles or pipes are employed as the loader. The device of the present invention may also be used in this type of apparatus. This apparatus is essentially a roller mechanism suitably driven, for instance, by a compressed air motor or an electric motor. Rolls [8 are generally surfaced with some nonsparking friction material, such as rubber, and

have "circumferential grooves "20 "adapted *to .,:passage of -'-the bore hole loadertherethrough, is

zprovi'dedztosserve as a conduit ortguideSindirect- "ing the borehole loader fromthe'rolls to:the:bore hole. ,Thisipermitsthe use ofra?relativelyflexible bore hole loader in operations where the roll mechanism is, by necessity, such a distance from the bore hole mouth as would ordinarily result in undue bending of the bore hole loader. Moreover, by the use of the device of the present invention, it is not necessary that the roller mechanism be directly in line with, and be positioned to exert a thrusting force axially to the bore hole as is the case when rigid sticks or pipes are employed as the loader. For example, in some operations it may be more convenient to position the roller mechanism such that it exerts a thrusting force at an angle deviating from the line of the bore hole, in which case the flexibility of the loader of the present invention coupled with its rigidity will transmit the thrusting force into a tamping force Within and axially to the bore hole.

In loading an explosive cartridge into a bore hole by the use of the present invention, the cartridge 2| is placed in the mouth 22 of the bore hole 23. The device of the present invention is then used to push the cartridge to the far end of the bore hole and then to tamp it, causing the paper wrapping of the cartridge to collapse and compacting the charge.

Considerable modification in the selection of the materials used in the sheath, core, tamping head and intermediate section if used, as well as in the means employed in securing the several parts together, is possible without departing from the scope of the invention.

What is claimed is:

l. A bore hole loader comprising an elongate core of spring metal, the sheath around said core and substantially the same length as said core, said sheath being composed of tough, flexible, non-sparking material, and a tamping head portion of hard, tough, non-sparking material rigidly attached to one end of the core and sheath assembly, said core and sheath assembly being substantially axially incompressible and inextensible and being sufficiently flexible to be bent in confined spaces.

2. The bore hole loader of claim 1 wherein the elongate core is of substantially circular crosssection.

3. The bore hole loader of claim 2 wherein the elongate core is spring steel wire, and wherein the sheath comprises rubber.

4. A bore hole loader comprising an elongate core, having substantially circular cross-section, of spring metal, a sheath around said core, said sheath being composed of tough, flexible, nonsparking material, and a tamping head portion of hard, tough, non-sparking material connected to one end of the core member by means of an intermediate length of non-sparking material which is rigidly attached directly to said core member, said core and sheath assembly being substantially axially incompressible and inextensible and being sufiiciently flexible to be bent in confined spaces.

5. The bore hole loader of claim 4 wherein the elongate core is spring steel wire, and wherein the sheath comprises rubber.

ROBERT MCGIRR.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date Doble Apr, 12, 1864 Walker Sept. 10, 1867 Baldwin Aug. 17, 1875 Iwan Nov. 20, 1883 Number

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