US3806025A

US3806025A - Stemming bag

Info

Publication number: US3806025A
Application number: US00282908A
Authority: US
Inventors: T Marshall
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-10-19
Filing date: 1972-08-23
Publication date: 1974-04-23
Anticipated expiration: 1991-04-23

Abstract

A blasting shot hole stemming bag to be filled with a noncompressible fluid and having a self-closing valve. The valve is formed of overlying strips of vinyl heat sealed along predetermined lines to provide a narrowed valve passage. The bag is fabricated of different thickness or different degrees of flexibility of the plastic vinyl or similar material and has heat seal lines forming the permanently closed end as well as the narrowed filler valve between the bag side walls, and additional heat seal lines restricting the bag top to a small mouth leading to the valve, the valve and valve passage being located within the bag and spaced substantially from the bag mouth to prevent objects from contacting the valve and accidentally opening it. By fabricating the bags so that opposite sides are of the material having the different degrees of flexibility, when filled with the fluid the more flexible bag side is pulled to a greater degree both longitudinally and laterally being evidenced by a pronounced direction of the side and end seams, with the attendant advantage that the bag material at the valve end of the bag is pulled downwardly in a very positive manner to provide a protective shield for the valve to preclude inadvertant opening of the valve during tamping into the shot hole. The bag material is further possessed of a stretchable characteristic enabling the bags to be elongated to reduce their cross-sectional dimension to facilitate their being placed into irregular size shot holes which may result from use of worn drill bits. Multiple bags, each with its valve, may be simultaneously formed by overlying suitable plastic strips and sheets, and forming heat seals along predetermined lines. Individual bags may be torn from the composite sheet by tearing along certain heat seal lines.

Description

United States Patent [191 Marshall Apr. 23, 1974 STEMMING BAG [76] Inventor: Thomas D. Marshall, Box 87,

Prosperity West, Va. 25909 H [22] Filed: Aug. 23, 1972 [21] Appl. No.: 282,908

Related US. Application Data [63] Continuation-impart of Ser. No. 81,776, Oct. 19,

1970, abandoned.

Primary ExaminerWilliam 1. Price Assistant Examiner-Stephen P. Garbe Attorney, Agent, or Firm-John E. Becker [57] ABSTRACT A blasting shot hole stemming bag to be filled with a non-compressible fluid and having a self-closing valve. The valve is formed of overlying strips of vinyl heat sealed along predetermined lines to provide a narrowed valve passage. The bag is fabricated of different thickness or different degrees of flexibility of the plastic vinyl or similar material and has heat seal lines forming the permanently closed end as well as the narrowed filler valve between the bag side walls, and additional heat seal lines restricting the bag top to a small mouth leading to the valve, the valve and valve passage being located within the bag and spaced substantially from the bag mouth to prevent objects from contacting the valve and accidentally opening it. By fabricating the bags so that opposite sides are of the material having the different degrees of flexibility, when filled with the fluid the more flexible bag side is pulled to a greater degree both longitudinally and laterally being evidenced by a pronounced direction of the side and end seams, with the attendant advantage that the bag material at the valve end of the bag is pulled downwardly in a very positive manner to provide a protective shield for the valve to preclude inadvertant opening of the valve during tamping into the shot hole. The bag material is further possessed of a stretchable characteristic enabling the bags to be elongated to reduce their cross-sectional dimension to facilitate their being placed into irregular size shot holes which may result from use of worn drill bits. Multiple bags, each with its valve, may be simultaneously formed by overlying suitable plastic strips and sheets, and forming heat seals along predetermined lines. Individual bags may be torn from the composite sheet by tearing along certain heat seal lines.

10 Claims, 9 Drawing Figures PATENTEDAPR 2 m4 3; 806; 025

SHEET 1 0F 2 INVENTOR THoMAs D. MARSHAL.

ATTORNEYS PATENTED APR 2 3 i974 SHEET 2 OF 2 STEMMING BAG BACKGROUND OF THE INVENTION This invention relates to improvements in devices for stemming, or closing, the open ends of blast, or shot, holes in mining operations, and particularly to waterinflatable bags for this purpose, and is a continuationin-part of my co-pending application, Ser. No. 81,776 now abandoned.

It is common practice in mining operations to undercut a section of the exposed face of coal, or other material being mined, and to drill a series of holes above the undercut to receive explosives to break loose the coal from the vein for transport from the mine. These holes, called shot holes, are closed by plugs, tamped wadding or other materials, and in other ways, to prevent the explosive from blowing out of the holes when fired, and to cause the explosive force to be exerted against the ore to be dislodged. Back-firing through the hole is extremely dangerous to workmen, and even with conventional forms of stemming there is considerable danger, both from flying debris and from dust. The dust is detrimental to health and also slows mining operations. Dust and smoke are considered two prime contributors to respiratory impairments such as Silicosis and occupational Pneumoconiosis (Black Lung).

It has been suggested that elongated bags filled with a fluid, such as water, and tamped into shot holes, will compress longitudinally while expanding perimetrically under explosive force and seal shot holes, and the bursting bag will release the fluid to saturate the dust of the explosion and prevent its escape into the mine. Water filled bags reduce the violence of the explosion and the dust is held to a minimum. The bursting of the water-filled bag will extinguish the fire and eliminate the ignition of any inflammable gas in the shot hole. The bags are usually equipped with a self-closing valve, so that when filled they will hold the fluid. The valve, however, is in the end of the bag, and often is exposed across the full end whereby it can be accidentally opened by a tamping rod in the normal bag seating operation. If this occurs, fluid escapes and a dangerous situation arises, for the bag will no longer function as a sealing member, but will blow out when the shot is fired. This condition is present because the fluid pressure within the bag tends to force the flexible valve element back toward the bag end where it can become fully exposed.

SUMMARY OF THE INVENTION The general object of the present invention is to provide an improved stemming bag for shot holes having improved characteristics whereby the valve end will not be subject to inadvertent release of the bag fluid during use.

A more specific object of the invention is to provide a stemming bag having a self-closing valve, with means to prevent the valve from becoming exposed at the bag end, even when the bag is inflated.

Another object is the provision of .a bag of this type having the valve recessed below or within the bag end, and the valve end opening restricted transversely to limit the area of access to the valve.

A further object is to provide a stemming bag which has a restricted access opening in one end leading to a self-closing valve, with the restricted access forming reinforcements in the valve end portion to stiffen the valve under pressure and assist in maintaining a seal. It is also an object of the invention to provide a stemming bag with reinforcements at the valve end, so that any rupturing under explosive force will occur below the valve end to release the fluid before the valve end.

has moved from the stemming position, and to thereby direct the released water toward the explosion and breaking ore to dampen the dust.

Still a further object is to provide an improved bag of the foregoing character which is fabricated of a flexible plastic material whereby opposite sides thereof have different degrees of flexibility so that when filled with the fluid the more flexible bag side is pulled to a greater degree both longitudinally and laterally so that the bag material particularly at the valve end of the bag is pulled downwardly in a very positive manner to provide a protective shield for the valve.

Yet another object is to provide a bag of the aforementioned type which is fabricated of a manually stretchable plastic-like material enabling the bags to be elongated if necessary to reduce their cross-sectional dimension to facilitate their being placed into irregular size shot holes which may result from use of worn or otherwise non-uniform size drill bits.

Other objects of the invention will become apparent from the following description of one practical embodiment thereof, when taken in conjunction with the.

drawings which accompany, and form part of, this specification.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a plurality of stemming bags integrally, but separably, joined in manufacture;

FIG. 2 is a perspective view of a pair of overlying plastic sheets forming the valve elements of the bag structure;

FIG. 3 is a side elevation of the completed bag, parts being broken away at the center to permit the bag to be shown on a larger scale;

FIG. 4 is a longitudinal section through the bag, taken on the line 4-4 of FIG. 3;

FIG. 5 is a perspective view of a liquid inflated bag, an inflating or filling tube being shown in place in the mouth of the bag;

FIG. 6 is a perspective view of the tube of FIG. 5, fully inflated and with the tube withdrawn and the valve closed;

FIG. 7 is a longitudinal section through the liquid inflated bag, taken substantially on the line 7--7 of FIG. 6, with the central portion of the bag being broken away;

FIG. 8 is a transverse cross-sectional view through the inflated bag at the valve area, as viewed on the line 8-8 of FIG. 6; and

FIG. 9 is a side elevational view of the improved stemming bag shown in position in a shot hole.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring to the drawings in detail, and first to FIGS. 1 and 2, a plurality of joined stemming bags and joined valve elements embodying the invention are shown. By making the bags in multiples in the form of a sheet from which individual bags can be removed, the manufacturing process is greatly simplified.

.. W W t The materials used to form the bags consist of two, relatively narrow, valve-forming strips 1 and two, wide, bag wall-forming sheets 2. For purposes of illustration, valve-forming strips 1 and bag wall-forming sheets 2 are shown of such dimensions as to provide only three, joined, valved stemming bags 3, but for practical purposes, ten or more bags may be formed as a unit. The material for both the valve strips and the wall sheets can be of a vinyl or vinyl-like material which is capable of multi-layered joinder by means of heat seals, or

seams.

The valve-forming strips 1 will be positioned one above the other and sealed, by appropriate heat sealing means, along lines 4, which are U-shaped and provide valve passages 5 between the legs of adjacent U-seams. This joins the strips together and prevents flow of fluid between the strips except through the passages 5 when assembled with the bag wall sheets 2.

Joined strips 1, of a suitable length are then placed between the pair of wall-forming sheets 2, with the long edges la of the joined strips 1 remote from the heat seams and one edge 2a of the wall-forming sheets in coincidence. This will position the valve elements near one edge of the wall-forming sheets so that the valves will be located at but recessed within one end of the completed bags.

The superposed elements 1 and 2 are heat sealed along

lines

6 and 7 inwardly of, and parallel to, the top edge 8 and the bottom edge 9. Heat seal lines or seams 10 are made longitudinally of sheets 2, parallel to each other and to the sides of the superposed elements, said seams being at equally spaced distances, equal to the desired bag width, between the side edges. Near the bag bottom, angular heat seams 11 extend from the longitudinal seams 10 to the bottom seam 7, with the seams ll diverging from opposite sides of each of the seams 10 toward the bottom seam. Similar angular seams 12 extend from each of the longitudinal seams 10 toward the top seams 6, but these seams stop short of the top seams 6 and interjoin with spaced seams 13 which are parallel to the longitudinal seams 10, to provide a restricted mouth area 14 leading into each valve passage. Of course, care is taken so that these mouth areas are not initially closed by the end seal, such as by interposing an interruptor piece or sheet, not shown, in each of the strategic mouth areas between said sheets 1, before completing the sealing of the extended seam 6 completely across each bag to otherwise join the valve elements 1 to each other and to the bag side walls.

The above-described operations will provide a sheet, or strip, of completed and joined bags, and not only enables a simplified manufacturing procedure to be used, but the resultant product is much easier to handle than a plurality of individual bags.

Also, storage is greatly facilitated through the use of flat, multi-bag sheets.

The heat seal lines 10 defining the several bags are made so as to also form tear-lines to permit single bags to be removed from the sheets while maintaining good longitudinal seals of the bags. Thus, by tearing along the longitudinal seams 10, individual bags, each with its own valve, will be readily obtained as needed, A tapered bottom end can be formed opposite the mouth end of the bag, if desired, by optionally tearing along the angular tear-seal lines 12 and the bottom seam 7. FIGS. 3-9 show the bag 3 as torn from the multi-bag sheet. While the excess material is very flexible, on occasion the excess material at the bottom may be removed to provide a clean tapered end 15 to better facilitate unhampered insertion into a predrilled shot hole 18 (FIG. 9). In FIG. 4, the mouth area 14 is shown spread open for access to the valve for filling.

The resulting stemming bag 3 has side walls 16, which are parts of the original plastic sheets 2, joined along the side edges by the remaining portions of heat seams 10. An important feature of this improvement bag is the use of two different kinds or types of the flexible vinyl or vinyl-like material for opposite sides of the bags. That is, the vinyl material is either of slightly different thicknesses, or if of the same thickness, they are of varying flexibility so that one bag side is capable of being pulled or more arcuately formed during fluid inflation, primarily in the longitudinal direction. This assures that the end marginal bag material is pulled downwardly over the ends of the bags to form protective shielding to be discussed in more detail hereinafter. The bag has a lower tapered end 15, closed by the bottom seam 7 and angular seams 11. The top is closed at each side of the mouth area 14, so that the mouth is not over one-half the width of the bag. The mouth passage flares somewhat below the parallel seams 13 and between the angular seams 12 but only to the points wherein the seams 12 cross the U-shaped valve-forming seams 4, as seen in FIG. 3. From these points, the passage then converges along the curving portions of the U-seams forming the restricted valve passage 5.

By reason of the mouth and valve construction, the valve passage 5 is purposely spaced inwardly some distance from the mouth area 14 and top end 8. At the same time, the mouth area is restricted widthwise of the bag to reduce the open area above, and leading into, the valve. Because of this, together with the result from the different degrees of flexibility of the bag sides pulling the bag ends 8 and 9 over as protective flaps, the valve cannot move outwardly into the mouth area under internal pressure, and none of the valve structure will be exposed when the bag is filled. Therefore it will be virtually impossible to accidentally contact or open the valve and release the fluid during normal operations of placing the bag in a shot hole and tamping it in place. The restricted mouth serves both as a second shield for the valve and an entrance to the valve which will allow insertion only of a tube of small enough diameter to enter the valve, but only after the pulled-over protective end flap is straightened out. Larger diameter implements, such as a tamping rod, cannot reach or penetrate the valve in this improved bag. An approved standard tamping rod is of wooden construction, 1 and one-half inch in diameter and about 10 to 12 feet in length.

In using the device, a tube, such as a tube 17 shown in FIG. 5, is inserted through the mouth 14 and into the valve passage 5, to spread the sides of the valve elements to assure free flow of fluid into the bag. Sufficient fluid is put into the bag preferably under some pressure to inflate it to predetermined degree. The tube is then removed. As the tube moves out of the valve passage, the pressure of the fluid within the bag, between the bag side walls and those portions of the valve-forming strips providing the sides of the valve passage, will press the passage walls into contact with one another to close the valve. No other sealing is necessary. Although the fluid pressure between the bag walls and the valve strip tends to bulge the valve upwardly toward the mouth, the convergent passage between the seal lines 12 resist this movement. Thus, the valve remains well down below the bag mouth, unexposed to chance contact with objects which might accidentally open the valve. At the same time, the restricted mouth prevents objects from getting into the bag mouth.

Moreover, when the bag is thusly filled, both of the ends have their marginal pieces between the

seals

6,7 and the respective

adjacent ends

8 and 9, pulled downwardly as protective end flaps due to the aforestated differences in degree of flexibility of the bag sides. Accordingly when a bag is placed into a predrilled shot hole 18, see FIG. 9, and tamped into place by means of the usual tamping rod, it is apparent that there is no possibility of the tamping rod entering the bag mouth to contact, and accidentally open, the valve and release fluid. By retaining the lower end marginal flap on the filled bag, it serves to reinforce that end of the bag and permits the bag to be inserted and tamped at either the top valve end or the opposite end.

The bag material may have a wall thickness of approximately 0.006 inch and is made of a clear vinyl or like material to permit the miners to readily observe as well as feel the filling fluid during inflation of the bags. In order for the valve to work more efficiently, the sheets 1 making up the valve components are preferably of only about half the wall thickness, or approximately 0.003 inch, thereby giving them a greater degree of flexibility to more readily close responsive to the pressure of the surrounding fluid. The materials used to comprise the bag sides and having the required characteristics set out hereinabove may be obtained from various manufacturers, but I have found that the Goodyear Company markets very acceptable types of both the soft and semi-soft or semi-hard vinyl-like products. More specifically, the Goodyear Company makes a very satisfactory 6 mil (0.006 inch) thick soft vinyl under the formulation identification No. Gl6C301l9. A very satisfactory semi-hard/semi-soft W polyvinylchloride material No. 804 is manufactured by the Hooker Chemical Company of Hicksville, New

York, and which is preferably also of the 6 mil thickness.

While one practical embodiment of the invention has been disclosed hereinabove, it will be understood that the particular details of construction shown and described are merely by way of illustration, and the invention may take other forms within the scope of the appended claims.

I claim:

l. A shot hole stemming bag adapted to be filled with a non-compressible liquid during stemming use, said bag comprising in combination, a pair of elongated flexible side panels in overlying position joined along their long side edges by heat seal seams and across their bottoms by a heat seal seam, a pair of flexible valve strips in overlying relation between the side panels flush with the top of the side panels and joined in the side panel side seams, heat seal seams joining the valve strips along horizontally spaced lines extending vertically upward from the bottom edges of the valve strips and defining a valve passage between them, heat seal seams inwardly of the side panel side seams extending downwardly from the side panel tops and transversing the valve-passage-defining seams joining the side panels and valve strips and defining between them an extrance mouth opening to the valve passage, said entrance mouth being restricted to substantially less than the width of the side panel tops, a heat seal seam across the top portions of the side panels, but spaced substantially below said flush aligned top ends of said side panels and valve strips forming a potentially protective end margin or flap, said seam serving to join said side panels respectively to said valve strips transversely of the bag width outwardly of said valve passage, and said seam also joining said valve strips together commencing adjacent opposite sides of said entrance-mouth-defining seams and extending into each side seam of said side panels, leaving said valve passage unsealed and free to be opened for filling use; and one of said side panels being more flexible than the other of said side panels so as to induce a pronounced pulling over in one direction of said top end protective end margin or flap when said bag is liquid filled for stemming use.

2. A shot hole stemming bag as claimed in claim 1 wherein, said heat seal seams that join said valve strips and define said valve passage, extend convergently from said valve strip side edges.-

3. A shot hole stemming bag as claimed in claim 2 wherein, the entrance mouth-defining-heat-seal seams extend from said side panel tops parallel to one another to a distance between said top heat seal seam and said valve passage-defining-seams and then diverge downwardly to the points of traverse of said valve-passagedefining seams.

4. A shot hole stemming bag as claimed in claim 3, wherein bottom portions of the sides of the side walls converge downwardly to provide a bag having a tapered end opposite the entrance mouth.

5. A shot hole stemming bag as claimed in claim 4 wherein, the side wall panels and valve strips are of a transparently clear vinyl material.

6. A shot hole stemming bag to be filled with a liquid and inserted into a shot hole during use, comprising in combination, an elongated flexible material body having opposite side panels with sides, bottom and top, a flexible self-closing valve attached to said side panels within the body adjacent, but spaced inwardly from said top leaving a top marginal piece of material to constitute a potential valve-protective flap when inserted bottom-end first, said top of said bag being closed from the side edges inwardly to an entrance mouth of restricted width opening to the valve; one of said opposite side panels being more flexible than the other of said opposite side panels so as to induce a pronounced pulling in one direction of said top marginal valveprotective flap responsive to said bag being filled with liquid for shot stemming use.

7. A shot hole stemming bag as claimed in claim 6 wherein, the entrance mouth width is not more than one-half the width of the bag top.

8. A shot hole stemming bag as claimed in claim 7 wherein, the valve includes a passageway opening to the bag body, and there is a throat between the entrance mouth and the valve passageway diverging from the mouth toward the passageway.

9. A shot hole stemming bag as claimed in claim 6 wherein, the bottom of the bag body tapers downwardly and terminates in a marginal bottom flap which also is pulled in said same one direction as said top marginal valve-protective flap for said same reason, and thereby constitutes a protective bottom end flap to re- 3,806,025 7 8 inforce the bottom-end portion of said bag during 10. A shot hole stemming bag as claimed in claim 6 valve-end-first insertion into a shot hole with the aid of wherein, the bag body and valve are of a transparently a conventional tamping tool pushing against said botclear vinyl material. tom end of said bag.

Claims

1. A shot hole stemming bag adapted to be filled with a noncompressible liquid during stemming use, said bag comprising in combination, a pair of elongated flexible side panels in overlying position joined along their long side edges by heat seal seams and across their bottoms by a heat seal seam, a pair of flexible valve strips in overlying relation between the side panels flush with the top of the side panels and joined in the side panel side seams, heat seal seams joining the valve strips along horizontally spaced lines extending vertically upward from the bottom edges of the valve strips and defining a valve passage between them, heat seal seams inwardly of the side panel side seams extending downwardly from the side panel tops and transversing the valve-passage-defining seams joining the side panels and valve strips and defining between them an extrance mouth opening to the valve passage, said entrance mouth being restricted to substantially less than the width of the side panel tops, a heat seal seam across the top portions of the side panels, but spaced substantially below said flush aligned top ends of said side panels and valve strips forming a potentially protective end margin or flap, said seam serving to join said side panels respectively to said valve strips transversely of the bag width outwardly of said valve passage, and said seam also joining said valve strips together commencing adjacent opposite sides of said entrance-mouth-defining seams and extending into each side seam of said side panels, leaving said valve passage unsealed and free to be opened for fiLling use; and one of said side panels being more flexible than the other of said side panels so as to induce a pronounced pulling over in one direction of said top end protective end margin or flap when said bag is liquid filled for stemming use.

2. A shot hole stemming bag as claimed in claim 1 wherein, said heat seal seams that join said valve strips and define said valve passage, extend convergently from said valve strip side edges.

3. A shot hole stemming bag as claimed in claim 2 wherein, the entrance mouth-defining-heat-seal seams extend from said side panel tops parallel to one another to a distance between said top heat seal seam and said valve passage-defining-seams and then diverge downwardly to the points of traverse of said valve-passage-defining seams.

6. A shot hole stemming bag to be filled with a liquid and inserted into a shot hole during use, comprising in combination, an elongated flexible material body having opposite side panels with sides, bottom and top, a flexible self-closing valve attached to said side panels within the body adjacent, but spaced inwardly from said top leaving a top marginal piece of material to constitute a potential valve-protective flap when inserted bottom-end first, said top of said bag being closed from the side edges inwardly to an entrance mouth of restricted width opening to the valve; one of said opposite side panels being more flexible than the other of said opposite side panels so as to induce a pronounced pulling in one direction of said top marginal valve-protective flap responsive to said bag being filled with liquid for shot stemming use.

9. A shot hole stemming bag as claimed in claim 6 wherein, the bottom of the bag body tapers downwardly and terminates in a marginal bottom flap which also is pulled in said same one direction as said top marginal valve-protective flap for said same reason, and thereby constitutes a protective bottom end flap to reinforce the bottom-end portion of said bag during valve-end-first insertion into a shot hole with the aid of a conventional tamping tool pushing against said bottom end of said bag.

10. A shot hole stemming bag as claimed in claim 6 wherein, the bag body and valve are of a transparently clear vinyl material.