CN1080443C

CN1080443C - Fire-resistant wires

Info

Publication number: CN1080443C
Application number: CN95194100A
Authority: CN
Inventors: J·D·密斯菲尔德; B·古帕; E·威廉斯
Original assignee: Raychem Ltd
Current assignee: Raychem Ltd
Priority date: 1994-07-14
Filing date: 1995-07-12
Publication date: 2002-03-06
Anticipated expiration: 2015-07-12
Also published as: DE69512242D1; JP4015694B2; DE69512242T2; KR970705149A; MY113998A; WO1996002920A1; EP0770259A1; CA2194993C; EP0770259B1; AU2895195A; AU696852B2; TW374182B; CA2194993A1; CN1152969A; KR100363600B1; JPH10503050A; IL114579A0; IL114579A

Abstract

Mica-wrapped wires for fire-resistant cables have an unusually low degree of overlap in the mica tape wraps, which unexpectably produces a smoother external profile while retaining an acceptable degree of fire protection. Two layers of glass-cloth-backed mica tape, preferably with a polymer film overlying the cloth, are preferably applied with their respective (low) overlaps staggered. This smoother wrapping is especially effective when thin (less than 0.8 mm) polymer coatings are to be extruded over the wrapped wire.

Description

Fire-resistant wires

The present invention relates to fire-resistant wires, when this electric wire or the cable that comprises them are in the fire, can guarantee complete (integrity) of circuit.

About the known example of this electric wire is to cover with inorganic fire proof material, its objective is to guarantee electric lead and insulation on every side when common organic polymer insulating barrier melts or burns.In different inorganic refractory cover, mica " paper " is usually first-selected, and following description for convenience is an example with the mica covering, but the present invention has more than and is limited to this material.

Increased glass web or polyethylene film in the mica paper as back lining materials, it is made into to be wound in to spirality the band on the electric lead, thereby produces fire resistance to a certain degree.The lead that mica twines is coated with conventional polymer usually and produces the electricity/engineering properties of requirement.In fire, polymer is burnt, but the completeness of cable is by the carbide maintenance of the polymer of mica sheet and insulation.From fire-resistance property, it has been generally acknowledged that mica is The more the better, belt can contain Different Weight mica (for example 80,20,160g/sqm).

Conventional mica tape spiralization typically has the overlapping of 30% to 50% (with respect to bandwidth) when twining, be used for still keeping protection when the lead that is wound is crooked, opens easily because overlap when bending.For meeting the requirements of refractoriness, method for optimizing is high overlapping degree.Problem is that belt is thick more, and heavy more just difficult more successfully winding is particularly on the lead of minor diameter, be easy to generate belt and damage, fold and twine very poor surface, such surface makes the back program process more difficult again, cause the last outward appearance and the characteristic of line unsatisfactory, so, Gao Du fire line if desired, usually select to increase the weight of mica tape, stand winding mass simultaneously and descend, perhaps select to twine 2 layers of belt, increased the diameter of line simultaneously.Also having a problem is to overlap to be with the glass web fracture that makes some enhancings easily, causes glass fiber outstanding from twister.Diameter of wire is more little, and belt is thick more, and this problem is just serious more, and partly cause also is the fracture extensibility of these bands very little (being generally 3%).The geometrical calculation suggestion needs higher ductility for tackling overlapping, but this can compensate with the compression belt in practice.For addressing this problem, belt provider has developed the alternative with the polymer film backing, though mica paper still keeps original not ductility, here have suspection, the reliability of the not delamination in twining layer that is belt is degenerated with the fire-resistance property that the belt of polyethylene backing is replaced behind the bonding belt of glass and the organic filler of silicon.The following fact has been aggravated these problems, and the mica tape that provides is the length that disperses, and for making the longer lead that is wound continuously, just requires every hundreds of rice mica tape just to splice once.Usually use the suitable adhesive tape that is connected in mica tape one end to splice, this causes splicing place to twine thickness increases.

These problems can be understood better by Fig. 3 a-3g, wherein:

Fig. 3 a represents to have in online 50% overlapping and twine of " ideal ";

Fig. 3 b represents the more real overlapping degree that reaches in the reality;

Fig. 3 c represents that line has typical 33% winding of single layer that overlaps;

Fig. 3 d representation class is similar to the bilayer that twines among Fig. 3 b and twines;

Fig. 3 e represents to have bilayer, the winding twisted wire that twines among similar Fig. 3 c;

Fig. 3 f represents the deficiency of (exaggerating) known winding; With

Fig. 3 g represents that the winding thickness that above-mentioned mica splicing tape causes increases.

Ideally, as shown in Fig. 3 a, visible width is that the mica take-up strap M of W is wound with lucky 50% overlapping continuously, and the mica tape thickness that so once twines the whole surface of back covering lead C is the twice of individual layer mica tape thickness.In the reality, this desirable the overlapping is difficult to reach, and Fig. 3 b represents more real result, has wherein produced band gap G, and this is to consider that mica M has certain thickness, just needs low overlapping degree to reach smooth winding.It is that the mica tape M of W is about the 33% once winding of carrying out with (hachure) degree that overlaps that Fig. 3 c represents by visible width.Visible width M is slightly larger than the actual width of band M, because have the nut winding angle between band and the lead axis.Because band gap G has reduced the validity of twining, preferably use two mica tape M1 and M2, shown in Fig. 3 d and 3e, guarantee have a few and have two-layer mica take-up strap at least.Fig. 3 f, for clarity sake some represents that known mica tape M is wound in the out-of-flatness that lead C go up to produce turgidly, has represented the fracture of the crisp enhancing silk F (being generally glass) that the stress because of the band that overlaps produces, it does not wish to produce.

The deficiency that mica twines, in addition above-mentioned because of mica tape splices the thickness increase that brings, and when having thick (1mm or bigger) polymer insulator to be applied to outside the mica twister, shown in Fig. 3 g, these deficiencies can both be tolerated.Width is that the mica tape M of W is wrapped on the lead C as before, but splicing tape S is present in two or more adjacent winding circles, because usually the length of splicing tape is greater than around required length of one week of lead C, particularly for the lead of minor diameter.The winding thickness that causes increases one times of splicing tape S thickness or twice can be clear that ((Fig. 3 d and the 3e) increments that overlap reach four times of S thickness if splicing is two bands, so this will be avoided in practice).Thick ambroin coating P, thick is 1 millimeter or bigger, as being squeezed on the mica twister, shown in the left side of Fig. 3 g (not in scale), at this moment, the out-of-flatness shown in this deficiency and Fig. 3 f just can overcome with the silk fracture with known method.But under the situation that the weight and volume that requires line must reduce, this rough covering is not wished to want.

In the high-quality electric wire with thin insulating material P ' coating, shown in Fig. 3 g the right, all problems that the top is mentioned twines the outward appearance and/or the characteristic of fire-resistant wires and/or makes the appreciable impact that efficient produces to be increased to some extent mica.Rough join domain must be cut off in some place, and this has limited the continuous length that can make wrap wire.

The present invention is with simple that surprising method has alleviated above-mentioned problem.

The invention provides a kind of electric wire that contains conductor, have a bottom refractory material on the conductor at least, spirality ground twines the inorganic fire proof material cover tape on it, and the overlapping between adjacent turn preferably is less than 5% less than 10% of bandwidth, and more excellent is less than 3%.

Preferably, bottom is wound on (preferably being contacted with) lead with also comprising an inorganic fire proof material band spirality.The crossover region of cover tape is preferably located between the crossover region of bottom band, keeps protection when so just can be online crooked, and the line bending causes the little overlapping of cover tape to be opened easily.

According to the present invention, find to reduce overlapping as top cover tape, can twine near maybe reaching real " flushing the edge ", have zero overlapping, obtain very level and smooth spiral and twine outer surface.This individual layer spirality winding with continuous bottom is useful for some purposes, depends on the material of further use, but the preferred bottom that comprises second kind of inorganic fire proof material in the above-mentioned spirality winding that uses.Preferably, the overlapping between the bottom band adjacent turn is less than 20% (more excellent less than 15%) of the bandwidth of second kind of band.

For avoiding feeling uncertain, to refer in particular to out speech " spiral " and be used for representing advancing herein as twining forward along cylinder, cylinder is represented by lead in this invention, it preferably has almost circular cross section, needn't get rid of the cross section of other shape certainly.

Speech " band " is used to refer to the strip thing that can twine to spirality lead here, is not subjected to specific standard, and the restriction of structure or material is unless specify here.

The present invention is to following electric wire advantageous particularly, and this electric wire is covered by organic polymer material, and mantle thickness is less than 0.8 millimeter, preferably less than 0.6mm, more excellent in 5mm, especially less than 0.4mm, be positioned at and preferably be connected the outermost surface of said take-up strap.

The overlapping of adjacent turn is not less than 2% of respective bandwidth in the preferred bottom, preferably is not less than 4%, and more excellent is not less than 8%.

Though use the belt of two or more different materials and/or width and/or weight per unit area for some purposes, preferentially select for use two kinds (or may be multiple) to have the belt of similar width and thickness usually, more preferably be basically identical.The overlapping of the circle of preferred outer cover tape is less than the overlapping of the circle of bottom.

Twine among the present invention and have clearly that extremely the reason of flatness is not clear fully, but obviously (not limiting the invention to this theory), preferred tectal support winding can provide " free movable " to a certain degree or loosen, thereby enhancing smoothness, also reduce partially mixed in overlapping or pressed (part " interlock ") mutually, thereby alleviated pressure and the out-of-flatness of overlapping.Conventional expanding near the big overlapping in belt centre obviously can not be accomplished this point.Preferred fiber backing is compared with the overlapping that reduces the polymer-backed mica tape approx, shows and can produce better smoothing effect.Above-mentioned easy crisp silk fracture also obtains reducing, and guess is because reduced the pressure of overlapping band according to the present invention.

In the type according to the band of a kind of preferred winding of the present invention, the fiber holder of each band is sparse fabric, preferably square fabric, and its tram or parallel are basically perpendicular to the length direction of band.Be the purpose in this invention, adjacent filaments in this sparse fabric is preferably left certain distance, this distance equals the average thickness of silk at least, and more excellent is the twice of an average thickness at least, preferably is not more than 20 times (more excellent is not more than 10 times) of an average thickness.Preferred fiber material is the glass cloth of braiding.

Choose the mica paper of polymer-backed type or other inorganic fire proof material especially as cover tape,, also be better than cloth backing belt aspect the defective avoiding causing by loose or broken filaments because they help obtaining very level and smooth profile.The backing of cover tape preferably contains continuous substantially organic polymer films, for example polyethylene or polyester film.Belt with polyethylene coating or film is used for can having got profit on above-mentioned fiber (fabric) backing and is combined in the preferred characteristics of fiber or fabric and polymer (film) backing.

According to the present invention, in two-layer (or multilayer) twined, the crossover region that covering (skin) is with was located substantially on the middle part between the bottom band overlapping.

Fig. 1 with reference to the accompanying drawings and Fig. 2 can more be expressly understood benefit of the present invention, in the accompanying drawing:

Fig. 1 illustrates according to a two-layer part that has reduced the structure that overlaps of the present invention;

Fig. 2 represents the smooth appearance of twining in contrast to the known results among Fig. 3 f; With

Fig. 3 a-3g represents the winding of prior art.

Among Fig. 1, the spiral with the mica band 20 of ground floor glass cloth backing on the lead 10 twines Open around, preferred belt square and to knit the glass fabric support and illustrate by peeling off Figure 22. Belt twines Around overlapping 10% (not in scale) that is approximately bandwidth that makes the circle that links to each other, as shown, overlapping 24 are tending towards slightly smooth, to obtain more level and smooth winding. Also allow bigger friendship in the bottom Folded. Second-phase like the covering of mica band 30 twine have bandwidth about 2% overlapping, overlapping excellent Selection of land is arranged in the overlapping centre in the tail band 20. These are little overlapping as previously mentioned such Be easy to produce significantly level and smooth winding.

The advantage of never suspecting greatly of the level and smooth winding that is obtained by the present invention is, and is available Heavy belt, the fire resistance that effective two-layer belt just can acquire a certain degree, this is former Need four layers (have as far as possible maximum overlapping two-layer). For example, two-layer glass cloth backing Mica band, its weight are 80g/m², to twine by Fig. 3 g, the covering of generation is tending towards being to the maximum in theory 320g/m²Four layers. The covering of this high level is in fact at 4 layers of belts lid On point just can reach, but the average coverage of sliver can be because band gap that the front was described Produce and littler.

Have found that, twine as shown in Figure 1 two and heavily be 120g/m²The mica band of glass cloth backing can advantageously basically reach coverage and be tending towards theoretical minimum 240g/m²Can provide Fire-resistant degree (sliver on average can be bigger, because have little overlapping). And then, work as splicing tape 40 when appearing on the mica band, reduces " mixing " effect performance of overlapping generation according to the present invention Go out advantage to a certain degree, the splicing overlapping 42 and 44 in has as shown weakened so substantially The problem of splicing tape double thickness effect is as shown in figure G.

As a result, thick (0.35mm) polymer insulation coating 50 can be by this as known method Press on take-up strap 20 and 30, littler and acceptable thickening only occur in splicing place 55. Constructed in accordancely go out thinner more smooth electric wire, improved production efficiency, reach with Former identical fire-resistant standard, the overlapping percentage of the light band that this former requirement is higher and/ Or thicker polymer coating.

Fire resistance can be measured by fire-resistant specimen, and fire-resistant specimen comprises by two not attached Mica wrap wire with the polymer insulation thing is twisted together, and puts then the copper braid. Fire-resistant Test according to IEC 331 (by International Electrotechnical Commission, 1 rue de Varemke, Geneva delivers) carry out, be heated to 950 ℃ ± 50 ℃. Braid ground connection, voltage is added on the lead. Surpass if the cable holding circuit is complete Just ended test in 60 minutes.

The present invention can be used for using any known suitable material and production method to make insulated electric conductor, particularly fire-resistant wires.A preferred example is described now, explanation invention further.

Example

Make 1.5mm ²The fire line explanation

1) the tin-coated copper lead of lead=7 gang 0.523mm composition nominal diameter is the round conductor of 1.50mm

2) lead is twined by the mica tape of 2 layers of glass cloth backing, and mica content is 120g/m in the mica tape ²Total tape thickness is 0.12mm.The width of two bands is 5mm, all presses identical nominal spiral pitch (every circle forward travel distance) and twines to same direction.

3) be wrapped on the industrial cable wrapping machine and carry out, twine and assembled 2 dress band operating heads with one heart on the machine.

4) wrapping machine has been set identical rotation direction and identical speed to each operating head, and nominal value is pitch and the left hand winding direction of 9.9mm.

5) regulate two statures and guarantee that upward band forms on the correct location with respect to following band.

6) diameter of the whole assembly in winding back is 1.93mm.

7) for obtaining approximate flat edges, band is typical 10% with the overlapping of being with down on the belt.

8) the thin viscosity splicing tape that is fit to is used in the splicing of making in the band, is used in the glass of belt carefully, does not make the mica face projection of splicing at belt.

9) splicing in every band will be staggered, and does not overlap.

10) wire insulating line production line of the winding lead available standards of so making carries out insulation processing.

11) pipe extruding or similar technique (original known) the slight diameter increase that is used for making the splicing of twining product to cause can be accepted.

12) use above technology, can carry out insulation processing with thermoplastic Halogen insulating compound (itself is known) twining lead.

13) twining extruding wall thickness on the lead at this kind is that this kind material of 0.35mm is practicable.

14) the diameter increase that is produced by the band splicing will cause the insulating barrier diameter to produce and the increase of twining same order.Splicing needn't be removed, and fire-resistance property and electric insulation and engineering properties can not weaken simultaneously.

15) insulated electric conductor of so making can be configured to multicore cable with known method, the steel overcoat that cable comprises further compacting and may require.

16) fire resistance (circuit integrity) of the cable of the good design of so making can reach 950 ℃ of the heating-up temperatures of IEC311 definition.

Claims

1. an electric wire that contains lead has at least one bottom insulating refractories on its lead, and spirality ground twines inorganic fire proof material insulation cover tape on it, and the mutual overlapping of belt adjacent turn is less than 5% of bandwidth, more preferably less than 3%.

2. according to a kind of electric wire of claim 1, wherein bottom comprises a kind of inorganic fire proof material band and is wound in spirally on the lead, and the overlapping region of cover tape is between the overlapping region of bottom band.

3. according to a kind of electric wire of claim 2, wherein the mutual overlapping between the bottom band adjacent turn is less than 20% of bottom bandwidth, preferably less than 15%.

4. according to a kind of electric wire of claim 2 or 3, wherein two bands have essentially identical width and thickness.

5. according to a kind of electric wire of claim 2 or 3, wherein the mutual overlapping part between the cover tape adjacent turn is less than the overlapping between the bottom band adjacent turn.

6. according to a kind of electric wire of claim 2 or 3, the overlapping of the cover tape part middle part between the overlapping part of bottom band substantially wherein.

7. according to a kind of electric wire of claim 1, wherein in the cover tape overlapping of adjacent turn less than cover bandwidth 2% or be substantially zero overlapping.

8. according to a kind of electric wire of claim 1, have the organic polymer material coating, its thickness is less than 0.8 millimeter, and preferably less than 0.6mm, more excellent in 0.5mm, especially less than 0.4mm, coating is covered in, and preferably is contacted with the outermost surface of cover tape.

9. according to a kind of electric wire of claim 1, wherein cover tape contains a kind of fibrous holder, preferably is made of inorganic material.

10. according to a kind of electric wire of claim 9, wherein the fiber holder is sparse fabric, preferably square fabric, and its equator or tram are basically perpendicular to the length direction of band.

11. a kind of electric wire according to claim 10, wherein adjacent fiber leaves certain distance in the fabric, this distance equals the average thickness of fiber at least, preferably is at least the twice of the average thickness of fiber, and preferably is not more than 20 times (more excellent is not more than 10 times) of fiber average thickness.

12. according to a kind of electric wire of claim 1, wherein covering has organic polymer material backing, the preferably basic continuous films of organic polymer material.

13. according to a kind of electric wire of arbitrary claim in the claim 9 to 11, wherein above-mentioned organic material backing is used as coating or the film on the fiber holder.

14. according to a kind of electric wire of claim 1, wherein the breaking ductility that has of cover tape is less than 5%.