GB2190458A

GB2190458A - Fuse tube with reinforcing element

Info

Publication number: GB2190458A
Application number: GB08710436A
Authority: GB
Inventors: David R Zoghby; Leon F Hines; Thomas D Sampson
Original assignee: Atlas Powder Co
Current assignee: Atlas Powder Co
Priority date: 1986-05-08
Filing date: 1987-05-01
Publication date: 1987-11-18
Anticipated expiration: 2007-05-01
Also published as: GB8710436D0; DE3714161A1; ZA872767B; BR8702359A; SE8701858L; CA1293202C; IN168030B; NO167651B; GB2190458B; AU594459B2; JPS6334500A; AU7263087A; NO871906D0; AT394551B; NO167651C; MX165082B; NO871906L; KR870011064A; SE8701858D0; SE465922B

Description

1 GB 2 190 458 A 1 SPECIFICATION ecomonics and also in achieving a good

bond between the reinforcing yarn(s) and the tube wall.

Fuse tube with reinforcing element 65 Also, it is advantageous because it allows a minimal wall thickness to be used while preventing blow outs TECHNICALFiELD of the tube wall f rom the reaction of the reactive

The present invention relates to an explosive signal filament bythe selective placement of the yarns in the fuse tube containing a reinforcing yarn and in tube wall. The single step process of the invention can particular a tube made from a lowyield strength 70 be performed while maintaining high production plastic containing one or more reinforcing yarns of a rates.' high tenacity and low elongation material to prevent SUMMARY OFTHE INVENTION longitudinal deformation of the tube, said yarns being The present invention provides for a signal tube extruded within the wall of the tube simultaneously constructed of a wall made of plastic material of low with the extrusion of the wall. 75 yield strength and containing therein one or more low BACKGROUNDART elongation, high tenacity reinforcement yarns which

In the field of explosives, high strength detonating resist longitudinal deformation of the resulting signal cord and lowstrength detonating cord are being tube. The reinforcing elements or elements are placed rapidly replaced by energy transmission devices in thetube in a single extrusion step. In the preferred which have little or no brisance. These signal devices 80 embodiment, the reinforcing elements are located in a have the advantage of increased safety and lower position substantially parallel to the axis of thetube.

noise levels making them particularly desirablefor Preferably, the element or elements are placed at a blasting operations closeto populated areas. Such a location from the insidewall of thetube which is 0.2 or signal transmission tube is disclosed in U.S. Patent less of the wall thickness.

4,290,366. Anotherfuse device is disclosed in U.S. 85 In another aspect, the present invention provides for Patent 3,590,739. a n extrusi o n ti p su ita b 1 e fo r p 1 aci rig th e rei nfo rcement A d isadva ntag e of the tu be uti 1 ized in co nstruction ya rn o r ya ms with i n th e tu be wa 11 as it is extru ded. The of the sig na 1 tra nsm issio n device such as that sh own tip comprises a wall defining a general cylindrical in U.S. 4,290,366 is thatthe signal tube which loosely shape with a first end which converges to the axis of contains the reactive element may be deformed 90 the tip. The first end of thetip forms one wall of a longitudinally a substantial length. In contrast, the passagewayforthe passage of extrudate when the tip reactive element insidethe fusetube has little is placed in a frame adjaceritto a die. A passageway is elasticity. As a result, in a borehole, and particularly a provided atthe center of the first end of the tip for the borehole filled with warm exposives, the tube may passage of the reactive elemeritto be placed in the stretch a considerable length; whereas, the reactive 95 tube. The converging walls of thefirst end form one element contained in thefuse tube does not stretch side of a passageway through which extrudate passes much. As a resuitthe blasting cap provided atthe end and contains one or more yarn placement passage of the tube may move awayfrom the end of the ways which provide a meansforthe placement of the reactive element contained within the tube. This can reinforcement yarn oryarns at preselected positions create a gap between the end of the reactive element 100 within the wal 1 of the fuse tube. 1 n the preferred and the receptacle end of the blasting cap. As a result embodiment, the yarn passageway(s) are comprised of this separation the reliability of the fuse and cap of members having channels therethrough which can assembly may decrease and it mayfail to initiate the be selectively positioned and an adjustment means is cap. Any reduction in reliability of the assembly is provided forthe adjustment and locking in place of the undesired. 105 yarn placement members. This permits variation of U.S. patent4,493,261 addresses the problem of the the position of the reinforcing yarn in the extruded stretching and breaking of fusetubes such as used in a tubewall.

construction of a device disclosed in U.S. Patent BRIEF DESCRIPTION OFTHE DRAWINGS

3,590,739 bythe incorporation therein of a plurality of A more complete understanding of the invention textile filaments positioned between an innertube 110 may be had by reference to the following detailed overwhich is laid the textile filaments followed bythe description when taken in conjunction withthe

50, extrusion of a second outside tube overthe insidetube accompanying drawings, wherein:

and filaments. This construction hasthe disadvantage FIGURE 1 illustrates a cross-sectional isometric of being complextoform by requiring several viewof a reinforced fuse tube.

extrusion steps and also having difficulties in achiev- 115 FIGURE 2 illustrates a cross-sectional view of the ing good quality bonds between the innertube, the extrusion tip of the present invention mounted on a outertube, and the filaments bonded therebetween. frame with the die.

Further such a process usually has slow rates of FIGURE 3 illustrates a cross-sectional area of one productions because two or more extrusion steps are embodiment of the present invention where the needed. 120 reinforcing yarns are positioned close to the outer wall In contrast, the present invention provides an of the tube.

apparatus and method for the selective placement of FIGURE 4 illustrates a cross-sectional area of one one or more reinforcing yarns in an extruded signal embodiment of the present invention where the tube in one step. This is advantageous in terms of both reinforcing yarn is positioned close to the inner wail The drawing(s) originally filed was (were) informal and the print here reproduced is taken from a later filed formal copy.

2 GB 2 190 458 A 2 surface of the tube. elongation at failure of 2-5%. Less preferred, but DETAILED DESCRIPTION useful in some cases, are yarns made from textile

Thefusetube of the present invention can be of any fibers having tensile strengths in the range of 90,000to desired shape. However, a generally circular cross lessthan about 200,000 psi and elongations atfailure section is preferred. The reactive element ofthe fuse 70of about 5-15%. Examples of these materials would may be of any reactive material known in the art, such include polyesters, nylons, and rayons. The reinforce as described in U.S. Patent No. 4,290,366which is ment yarns may be of the monofilament, multifila hereby incorporated by reference. FIGURE 1 shows merit, orspurttype. The reinforcing yarn can be made the cross section and isometric view of the fuse tube. from a combination of suitable materials. The yarn Thetransmission tube 10 contains a reactive element 75 material must also not degrade atthe temperatures 14. As described above, the reactive element may be used for extrusiorrof the tubewall 12, which are any of those known in the art. The wall 12 of elongated generallyfrom about 350?Fto,450'J. The reactive tube 10 is also preferably formed of a relatively flexi bl e elements 14 used in theart usually decompose or polymeric material. As used herein, theterm "flexi- react at about 600'1. Therefore the above range for ble- refersto the ability of elongated tube 10 to bend 80 extrusion provides a safety margin forthe extrusion of longitudinally. Examples of acceptable materials in- the tube wall. The reinforcing yarns maintain their clude polyethylene, polypropylene, polypropylene useful tensile properties over the Intended use copolymer polyvi nylch lo ride, polybutylene, ionom- temperature range of -40'Fto 150'F.The reinforcing ers, nylons, Surlyn (a trademark of DuPontfor its yarns preferably remain flexible overthe intended use ionomer) and mixtures of these. Preferabiythe plastic 85 temperature range of-40'Fto 1500F.

is onewhich will remainflexible overthe normal use An elongated plastictube such astube 10 but temperatures encountered bythefusewhich are withoutthe reinforcing yarns having an outside normallyfrom about-40'Fto about 150'F. Further,the diamater of 0.150 inch and an internal diameter of plastic preferably is one which flows and may be 0.050 inch and made of LLDPE (linear low density extruded at less than the temperature atwhich the 90 polyethylene) generally has a yield point of about 20% reactive element 14 decomposes or reacts. elongation u nder a force of about 10 pounds and The outer diameter of elongated tube 10 is prefer- typically fails at elongation of severa i h undred per ably about 0.12 inch to 0.15 inch and the internal cent. The yield point is the lowest stress at which a diameter is preferably about 0.05 inch. The practical material undergoes plastic deformation, below this range of the outer diameter is from about 0.06 inch to 95 stress the material is elastic, and above it is plastic. In about.30 inch and the practical range of the internal comparison an elongated tu be 10 of the same material diameter is from about 0.02 inch to about 0.15 inch. and dimensions in combination with reinforcing yarns The tube may be of larger dimensions if desired. 16would typicallyfail at an elogation of 2-3% at a In selecting an outer diameter, internal diameter tensile force of 30 lbs. or greater depending on the and material of construction for elongated tube 10, it is 100 number, size, and type of reinforcing yarns 16.

desirableto considerthe energythatthe reactive Advantageously, the reinforcing yarns, when over element 14will release during reaction so that stressed, will break and the sudden force imparted on elongated tube 10 has walls of sufficient strength to the tubewall in the area of the broken yarn(s) will avoid rupturing. In this manner, accidental initiation of rapidly neck and make it obvious to the userthatthe other explosive devices located proximatelyto the 105 signal tube should no longer be used. The user may energy transmission device can be substantially then simply cut outthe damaged portion of thetube eliminated. Also, destructionn or injuryto the sur- and utilizethe remaining portions, ortake other roundingswill also be similarly eliminated. appropriate action.

Contained within thetube wall 12 are reinforcement The reinforcing element(s). can be madefrom any yarns 16. (One of the reinforcing yarns is shown in 110 flexible, high tenacity, low etong.ation material. Prefer phantom). Two reinforcement yarns 16 are shown in ably a nonconductive material, is used. Suitable FIGURE 1; however, one yarn may be used or more materials include fiberglassand rayon.

than two yarns may be utilized. Two yarns are The fusetube is manufactured by known extrusion preferred. When more than one yarn is used it is techniques togetherwiththe implementation of the preferredthey are spaced equidistant around the tube. 115 extrusion tip provided bythe present invention.

Theyarn(s) are deposited in the tube wall during the Plastic material to form the tubewall is heated to the extrusion of thetube wall in a single step. desired temperature so that itwill flow and be The reinforcement yarns 16 are made from anyVarn extrudable. From the melt chamberthe plastic is material of high tenacity with low elongation prop- forced into an extrusion device. Suitable devices are erties. Preferably a nonconductive material is used. 120 known in the art and generally constitute a frame Most preferred are yarns made from textilefibers which holdsthe tip and a die. The frame, extrusion tip having tensile strengths in the range of 200,000 to and die are positioned to form a passageway th rough about 750,000 p.s.i. and elongations atfailure (where which the extrudate is forced between thetip and the the yarn breaks) of 1.5-4%. Examples of such prefer- dieto form the desired shape of the tube. Theformed red materials would be yarns of fiberglass, aramids 125 tube exits from the die and then is subsequently (sold by DuPont under the trademark Keviar) and quenched with waterto assure the extrudate has set.

carbon. Ayarn made from these preferred materials The present invention is highly desirable in thatthe and used as a reinforcement yarn 16would have a rei nfo rcement yarn can be placed within the tube in a diameter of 0.008 to 0.030 inches, a breaking strength single extrusion step. This is accomplished by provid- under a load of 10 poundsto 75 pounds, and 130ing member(s) thatform yarn passageways through 3 GB 2 190 458 A 3 the extrusion tip. circular. Maintaining a generally circular outside cross FIGURE 2 shows a crosssectional view of the section allows for enhanced ability to form a water extrusion tip 20 of the present invention mounted on a tight seal when a blasting cap is attached to one end of frame 22 in conjunction with a die 24 to form a the tu be. A seco n d adva ntage is that th is a] lows passageway 26 fo r the passag e of extru date. Extru70ma i nten a nce of a rel atively th ick seg ment of wa 11 date enters the passageway 26 from the melting rep rese nted by y wh ich is coh e rent. Th is is im po rta nt means th roug h open i n gs 27 as sh own by the a rrows. to prevent th e tu be wa 1112 f rom ru ptu ri ng du ring The tip 20 h as a g enera 1 ly cyl i n d rica 1 wa 1128, wh ich at reaction of the reactive element 14, while maintaining the first end 30 tapers to a point coincident with the a minimal thickness of the tube wall 12.

axis 32 of th e tip 20 wh ere a reactive el ement 75 R u ptu ri n g of the tu be ca n a Iso be red uced by p] aci ng passageway 34 is provided through which the reactive th e rei nfo rcementya rns n ea r the outer su rface of the element of the fuse is fed i nto the fo rm ed tu be (tu be 36 tu be su ch th at V is 20 % or less of t, the wa 11 th ickness.

shown in phantom, reactive element and reinforcing However, this is not preferred as ittends to distort the yarns not shown). The tip 20 as shown also has two circular cross section of the outer surface 64 of the reinforcement yarn channels 38 formed by members 80 tube into an elliptical shape of the outside of thetube inserted into holes in the tip 20. Member 40 forms a such as shown in Figure 3. Such an elliptical shape is channel or passagewayfrom the inside of thetip 20 less desired because it is more difficuitto achieve a through thetipwall 28 and exitsthetip on surface 42 reliable waterproof seal when a blasting cap is which forms one side of extrudate passageway 26. attached to the end of thetube.

The members 40 are held in place by any suitable 85 The placement of the yarns 16 closerto interior means such as set screws 44. The channel members surface wall 60 of the tube can deform the circular passthrough thewall of the tip to connectthe cross section of the interior as shown in Figure 4 inside of thetip 47 with or beyond the surface 42 of the without detrimental effects on the functioning of the tip which forms one side of the extrudate passageway fuse, while maintaining the circular cross section of 26. The yarn passageways or channels may be formed 90 the outer surface 64 of the tube to achieve a good seal merely by drilling holes in the tip 20. The size of the with a blasting cap. For example, the nominal outside channel 38 in member 40 is of sufficient diameterto diameter of fuse with the reinforcing yarns close to the allow passage of the yarn diameter selected while outer surface may be 0. 150 inch with variations in small enough to prevent backflow of extrudate into diameterfrom 0.140 to 0.160 inch; whereas, a tube the inside of the tip 47. Thetip may be constructed of 95 with the reinforcing yarns close to the interiorwall can any conventional material such as steel or stainless have a nominal O.D. of 0. 150 inch with variations from steel. 0.148 to 0.152 inch.

The yarn channels 38 shown in FIGURE 2 are Generally, the reinforcing yarn diameter can be illustrated as being provided by hollowtubesthat can between.008 inch and 0.30 inch fortubes with wall be positioned adjustably. When the set screw 44 is 100 thickness. The size of the reinforcing yarn can be loosened, the position of member 40 can be adjusted. varied depending upon the wall thickness of the tube, This allows the position of the yarns to bevaried the positioning of the yarn, and the amount of within the wall of the signal tube. By extending the end variation in the outertube diamaterthatcan be of member40within passageway 26furtheraway tolerated. For good bonding between the plasticof the from surface 42 of thetip, the reinforcing yarn is 105 wall and the reinforcing yarn,thewall thickness positioned closerto the outer surface of theformed should be.01 inch greaterthan the diameter of the tube. By moving this end of member40 closerto reinforcing yarn. For rupture resistance, thewall surface 42,theyarns are positioned closerto the thickness should betwo orthreetimesthe reinforcing interiorsurface of thetubewall. Other means forthe yarn diameter. For a verythickwall the placement of adjustment of member40 may be provided. Thetip of 110 the reinforcing yarn is less critical. Asthetubewall the present invention may be utilized to placethe thickness increasesforthe same strength of reactive reinforcing yarn oryarns at any preselected position in element 14the placement of the reinforcement yarn thetubewall. The advantagesto an adjustable bevaried morewidely and still maintain tube integrity.

reinforcement yarn channel provided by member40 is For example, a tubewall with a thickness of.1 5 inch in thatit permits easyvariation in the positioning of the 115 many instances ruptured upon initiation of the reac reinforcement yarn. The members 40 may be varied tive element 14when the reinforcement yarn was independently of each other. placed midway in the wall thickness. In contrast, when Referring to FIGURE 1, which shows a cross- the reinforcement yarn was positioned close to the sectional area of the tube 10, the nominal wall inner wall where x was.2 t or less the tube did not thickness of the tube is represented by a small t. The 120 rupture, when the same strength reactive elementwas distance from the interior wall 60 of the tube 10 used.

radially outward to the midpoint 62 of the yarn 16 is The reinforcement yarn is preferably placed sub identified as x.The distancefrom the midpoint 62 of stantially parallel to the longitudinal axis of the tube.

reinforcement yarn 16to entertothe outer edge 64 of Although a slight helical pattern is possible it is less thewall 12 is identified asy. 125 desired because itwould permitfurther elongation of In a preferred embodiment, x is 20% or less of t, the the tube prior to fail u re of rei nforcing yarn than when tube wall thickness. This has two advantages. Fi rst, it the element is placed substantially parallel to the axis places the reinforcement ya rn close to the i nterio r of the tube.

passageway of the tube minimizing deformation of It is i m po rtant to ach ieve a good bond between the the outside tube wall and maintaining it relatively 130 reinforcement yarn and the tube wall. This prevents 4 GB 2 190 458 A 4 thetubewall from sliding overthe reinforcement inch exhibited infrequent blowouts whereas, tubes yarn(s) andthus elongating an undesirable distance.A constructed where x = 0.02 inch frequently exhibited good bond is generally assured by using a coupling one or more blow outs every several feet. These blow agent. The coupling agent is any of those suitable and cuts were in the form of slits.

known in the art for achieving a good bond between 70 The above dscription is intended to describe the the tube material and the material from which the preferred embodiment and obvious variations would reinforcing yarn is made. be apparentto those skilled in the art.

Claims

The coupling agent may be applied in two manners. CLAIMS

One manner is to coatthe reinforcing yarn with the 1. A reinforced tube which resists longitudinal coupling agent priorto its extrusion within the 75 deformation comprising:

material making thetubewall. Forexample,when the (a) a wall comprised of a lowyield strength plastic tubewall is constructedfrom polyethyiene (LLDPEfor defining a tubewith a passgewaytherethrough; and example) andthe reinforcing yarn is fibreglass, the (b) one or more reinforcementyarns of a high coupling agent is a Polyester Resin Compatible Finish tenacity and low elongation material which has been applied, by Owens Corning Fiberglass, to thefiberg- 80 deposited within said wall, said filaments being lass yarn which is then extruded within the tube wall. positioned substantialy parallel to the longitudinal Another method is to admixthe coupling agent with axis of the tube.

the plastic utilized to makethe tubewall and then
2. The reinforced tube of Claim 1 wherein said low extrudethe mixture to form the tube wall. For yield strength plastic is selected from the group example, when the tube wail is constructed from 85 comprising polyethylene polyvinylchloride, ionomers polyethylene and the reinforcing yarn is fiberglass,the poiybutene, nylons, polypropylene, polypropylene coupling agent,titante sold underthetrade name copolymers and mixtures thereof.

CAPS L44/E by KENRICH Petrochemicals, Inc., is
3. The reinforced tube of Claim 1 wherein said added to the polyethylene when it is melted and then reinforcement yarn has a tensile strength in the range the tube is extruded with the fiberg lass within the wall. 90 of 90,000 to about 750,000 pounds per square inch and The reinforcing yarn maybe a single strand of exhibits failure at less than 15% elongation.

material, such as a minofilament, or it may be made
4. The reinforced tube of Claim 1 wherein said from a group of twisted filaments which forms a reinforcement yarn has a tensile strength in the range multifilament or spun Var. Yarns made from twisted of about 200,000 to about 750,000 pounds per square strands provide a rougher surface which can improve 95 inch and exhibits failure at less than 4% elongation.

the coupling of the yarn to the tube wall material by
5. The reinforced tube of Claim 1 wherein said the greater surface area. The following examples reinforcement yarn of high tenacity and low elonga demonstrate the present invention. tion material is selected from the group comprising EXAMPLE 1 fiberglass, aramids, carbon and combinations thereof.

Atube wall was made by heating polyethylene to a 100
6. The reinforced tube of Claim 3 wherein said temperature of about 360'1 and extruding itwithout reinforcement yarn is selected from the group com any reinforcement yarn to form a tube with a nominal prising fiberglas, aramids, carbon, polyester, rayon, outside diameter of 0.150 inch and a nominal interior nylon, and combinations thereof.

diamater of 0.050 inch giving a nominal wall thickness
7. The reinforced tube of Claim 4 wherein said of 0.05 inch. This tube was then subjected to a 105 reinforcement yarn is selected from the group com longitudinal stress of 20 pounds. The tube demons- prising fiberglass, aramids, carbon, and combinations trated a yield pointatabout 15% elongation underthis thereof.

stress andfailed atgreaterthan 600% elongation.
8. The reinforced tube of Claim 2 wherein said EXAMPLE 2 reinforcement yarn has a tensile strength inthe range A tube was constructed in accordance with the 110 of 90,000 to about 750, 000 pounds persquare inch and present invention by extruding the same material exhibits failure at lessthan 15% elongation.

utilized in Example 1 but by incorporting two reinforc-
9. The reinforced tube of Claim 2 wherein said ing yarns in the tube wall wheret, the wall thickness, reinforcement yarn has a tensile strength in the range was 0.50 inch and xwas =to 0.01 inch. Thistube of about 200,000 to about 750,000 pounds per square showed 1 % elongation underthe 20 pounds stress. 115 inch and exhibits failure at lessthan 4% elongation.

The tube failed at a stress of 38 pounds and an
10. The reinforced tube of Claim 8 wherein said elongation of 4%. reinforcement yarn is selected from the group com EXAMPLE 3 prising fiberglass, aramids, carbon, polyester, rayon, To demonstratethe significance of the placement of nylon, and combinations thereof.

thefiber in the tube wall, tube waliswere constructed 120
11. The reinforced tube of Claim 9 wherein said of nominal thickness of 0.43 inch. Tubes were then reinforcement yarn is selected from the group com constructed wherein the reinforcement yarn was at a prising fiberglass, aramids, carbon, and combinations position where x equaled 0.01, 0.02 and 0.03 inches. thereof.

The tubes contained the same strength reactive
12. A reinforced energy transmission tube which element of the type identified in U.S. Patent 4,290,366. 125 resists longitudinal deformation comprising:

The reactive elementwas nitrocellulose yarn and (a) a wall made of a lowyield strength plastic polyester yarn twisted toform a continuous reactive material defining a tube with a passageway there element aboutO.01 inch in diameter. On the initiation through; ofthe reactive element, the tubes wherexwas 0.01 (b) a reactive filament of a self-oxidizing material inch did not blowout; and the tube wherexwas 0.03 130 loosely contained within the passageway of said tube; GB 2 190 458 A 5 and portion of the extrudate passageway, the channel (c) one or more reinforcement yarns of high tenacity opening intothe passageway th rough which extru and low elongation material, the yarns havingtensile date movesto permit passage of reinforcing yarn strength in the rangefrom about90,000to about therethrough and intothe extrudate.

750,000 pounds persquare inch and exhibiting failure 70 26. The tip of claim 26 wherein said member is at an elongation at less than 15% elongation and movable within said tip.

which have been deposited within said wall of said 27. The tip of claim 27 further comprising means tube in a position substantially parallel to the axis of for holding said movable member in place.

thetube. 28. A reinforced tube substantially as hereinbefore
13. The reinforced tube of Claim 12 wherein said 75 particularly described and as illustrated in the accom lowy[eld strength plastic is selected from the group panying drawings.

comprising polyethylene polyvi nylch 1 o ride, ionomers 29.An extrusion tipto be used in combination with a polybutene, nylons, polypropylene, polypropylene die for extruding a tube substantially as hereinbefore copolymers and mixtures thereof. particularly described and as illustrated on the accom 15,
14. The reinforced tube of Claim 12 wherein said 80 panying drawings.

reinforcement yarn is selectedfrom the group com prising fiberglass, aramids, carbon, polyester, rayon, Amendmentsto the claims have been filed, and nylon, and combinations thereof. - havethe following effect:
15.The reinforcedtube of claim 13wherein said Claims 1, 12,25,26and 27 above have been deleted reinforcement yarn is selectedfrom the group com85 or textually amended.

prising fiberglass,aramids, carbon, polyester, rayon, New or textually amended claims have been filed as nylon, and combinations thereof. follows:
16. The reinforced tube of Claim 12 wherein said Claims 28 and 29 above have been re-numbered as reinforcement yarn has a tensile strength in the range 26 and 27 and tkfeir appendancies corrected.

of about 200,000 to about 750,000 pounds per square 90 WHAT IS CLAIMED IS:

inch and exhibits failure at less than 4% elongation. 1. A reinforced fuse tube which resists longitudin
17. The reinforced tube of Claim 16 wherein said al deformation comprising; reinforcement yarn is selected from the group com- (a) a wall comprised of a lowyield strength plastic prising fiberglass, aramids, carbon, and combinations defining a passageway therethrough in which a thereof. 95 reactive element may be placed said wall having an
18. The reinforced tube of Claim 14 wherein said external diamater of 0.3 inches or less; and reinforcement yarn has a tensile strength in the range (b) one or more reinforcement yarns of a high of about 200,000 to about750,000 pounds per square tenacity non- conductive material exhibiting 5% or inch and exhibitsfailure at less than 4% elongation. less elongation atfailure deposited within said wall,
19. The reinforced tube of Claim 18 wherein said 100 said reinforcement yarn, being positioned substantial reinforcement yarn is selected from the group com- ly parallel to the longitudinal axis of said fusetube, prising fiberglass, aramids, carbon, and combinations said reinforcement yarns being adapted tofail when thereof. said fusetube is elongated 5% or less such failure
20. The tube of Claim 12 wherein the distance from causing a visible depression in the area of failure the interior surface of said wall to the axis of the 105 allowing the user to identify a defective tube.

reinforcement yarn is.20 or lessthan the nominal 12. A reinforced energy transmission tube which thickness of the tube wall. resists longitudinal deformation comprising:
21. The reinforced tube of Claim 20 wherein said (a) a wall made of a low yield strength plastic reinforcement yarn is selected from the 9 rou p com- material defining a passageway thereth rough said prising fiberglass, aramids, carbon, polyester, rayon, 110 wall having an outside diameter of 0.3 inches or less; nylon, and combinations thereof. (b) a reactive filament of a self- oxidizing material
22. The reinforced tube of Claim 20 wherein said loosely contained within the passageway; and reinforcement yarn has a tensile strength in the range (c) one or more reinforcement yarns of high of about200,000to about750,000 pounds per square tenacity, nonconductive and low elongation material, inch and exhibits failure at lessthan 4% elongation. 115 the yarns havetensile strength in the range of from
23. The reinforced tube of Claim 22 wherein said 90,000 to about 750,000 pounds per square inch and reinforcement yarn is selected from the group corn- exhibiting failure at 5% or less elongation, said prisIngfiberglass, aramids, carbon, and combinations reinforcement yarns are deposited within said wall thereof. and said tube in a position substantially parallel to the
24. The reinforced tube of Claim 20 wherein said 120 longitudinal axis of said tube, said yarn exhibiting reinforcement yarn is selected from the group com- failure at 5% or less elongation of said reinforced tube prising fiberglass, aramids, carbon, and combinations such failure thereby causing a visible depression in thereof. the area of failure allowing the userto identify a
25. An extrusion tip to be used in combination with defectivetube.

a die forthe extruding of a tube comprising a tip, the 125 25. An extrusion tip to be used in combination with exterior surface of said tip defining a portion of the a die for the extruding of a tube comprising a tip, the wall of a passageway for movement of extrudate exterior surface of said tip defining a portion of the through the mold formed by the tip and die, a member wall of a passageway for movement of extrudate defining a channel in said tip, said member passing through the mold formed bythe tip and die, an through the exterior surface of the tip which forms a 130 adjustable tubular member defining a channel in said 6 GB 2 190 458 A 6 tip, said adjustable tubular member passing through the exterior surface of the tip which forms a portion of the extrudate passageway, the channel opening into the passageway through which extrudate moves to permit passage of reinforcing yarn therethroug hand into the extrudate, and a means for holding said adjustable tubular member in a selected position.

Printed in the United Kingdom for Her Majesty's Stationery office by the Tweeddale Press Group, 8991685, 11187 18996. Published at the Patent Office, 25 Southampton Buildings, London WC2A lAY, from which copies may be obtained.

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