US2958919A - Method and apparatus for producing insulating material - Google Patents

Description

s. PALMER 2,958,919

METHOD AND APPARATUS FOR PRODUCING INSULATING MATERIAL Nov. 8, 1960 Filed Feb. 12, 1959 2,958,919 Q6 Patented Nov. 8, 1960 NLETHOD AND APPARATUS FOR PRODUCING INSULATING MATERIAL Stanley Palmer, Brighouse, England, assignor to Versil Limited, Liversedge, England, a British company Filed Feb. 12, 1959, Ser. No. 792,812 Claims priority, application Great Britain May 14, 1958 3 Claims. (Cl. 28-1) This invention is particularly concerned with improvements in the production of webs or mats formed or composed of extrudable filamentary material, such as glass fibre, and applicable primarily for the purpose of thermal insulation in industrial buildings, plant, aircraft, refrigerators and the like.

Various methods have before been proposed for forming webs or mats from filamentary material by applying strands composed of grouped monofilaments on to a belt conveyor either in continuous or short so-called staple lengths in such manner as to build up a web or mat of the required thickness, a suitable binder being applied to retain the form of the Web or mat. Webs or mats produced by the known methods referred to are particularly suitable for the manufacture of reinforced glass fibre laminates.

The present invention, however, is concerned with producing webs or mats suitable for thermal insulation, and for this purpose it is desirable that the web or mat should have'the highest possible degree of porosity or still air content.

The present invention has for its object to provide an improved method and apparatus for the production of webs or mats from extrudable filamentary material whereby the filamentary material may be delivered on to a conveyor in the form of short curled lengths or portions to form a web or mat having a high thermal insulating capacity.

According to the present invention, a method for the production of a web or mat for thermal insulation purposes comprises causing a strand composed of grouped monofilaments to execute a sharp change in direction whereby the strand is caused to assume a curled formation, separating the curled formation into short lengths and delivering the curled short lengths on to conveyor means in such manner as to build up a web or mat having a high degree of porosity.

More specifically, the invention includes a method for the production of a Web or mat for thermal insulation purposes, which comprises attenuating and grouping to. gether a number of continuously extruded filaments to form a strand, drawing the strand so formed over or through means adapted to induce differential tensional stresses in the individual monofilaments of the strand so that the strand is caused to assume a curled formation, separating the curled formation into short lengths and delivering the curled short lengths of strand on to conveyor means in such manner as to build up a web or mat.

The invention includes apparatus for carrying out the method above defined, comprising means for attenuating and grouping together a number of continuously formed monofilaments to form a continuous strand, an air traction device arranged to draw the strand so formed over or through means causing the strand to execute a sharp change in direction whereby differential stressing of the individual monofilaments results in a curled formation of the strand fed into an outlet pipe delivering on to conveyor means, the arrangement being such that intermittent obstruction of air flow through the outlet pipe by tne curled fibres and consequent pressure built up behind the curled fibres successively severs curled portions from the continuous strand for discharge through the outlet pipe on to the conveyor means. A sharp change of direction of the strand may be obtained by drawing the strand over a knife edge or the like arranged adjacent the inlet to the, air traction device by which the curled portions are separated from the strand and delivered on to the conveyor means. Grouping of the individual monofilaments may be efiected in known manner by the use ofa V-grooved drum on which the grouped filaments are tensioned by means of an air traction device which delivers the continuous strand to the curling, severing and delivering means constituted by the air traction device first referred to.

According to a further feature of the invention, the conveyor means comprises upper and lower endless conveyors spaced apart according to the desired thickness of the web or mat to be built up. Means are provided for spraying the curled portions separated from the strand with a suitable binder and for drying or curing the binder as the web or mat is carried by the conveyor means to a discharge point. The spacing between the upper and lower endless conveyors may be adjustable to regulate the thicknessof the finished web or mat. Moreover, the rate of feed of the endless conveyors may be controllable to regulate the density of the web or mat.

The invention includes webs or mats produced by the method and/or apparatus herein defined.

The invention is hereinafter described, by way of ex-' ample, with reference to the accompanying drawings in which: I

Fig. 1 is a diagrammatic view showing apparatus constructed and arranged for carrying out the method according to the invention;

Fig. 2 is aside elevation of part of the apparatus shown in Fig. 1; and

Fig. 3 is an end elevation of the apparatus shown in Fig. 2.

In carrying the invention into effect according to one embodiment, continuous monofilaments 1 of glass extruded from a furnace 2 are collected by means of a hopper 3 and led into a V-groove 4 in the periphery of a drum 5 whereby the monofilaments 1 are grouped together. An air traction device 6 is arranged to withdraw the continuous strand 7 composed of the grouped monofilaments 1 from the drum 5 and to exert sufiicient tension for attentuating the monofilaments 1 in their passage from the furnace 2 to the drum 5. The air traction device 6 delivers the strand 7 through a pipe 8.

From the outlet of the pipe 8 the continuous strand 7 is drawn by the action of an air traction device 9 over a knife edge 10 arranged adjacent the inlet to the air traction device 9 so that the strand 7 is caused to execute a sharp change in direction whereby the individual monofilaments are differentially stressed so that the strand passing into an inlet portion of an outlet pipe 12 assumes a curled formation. As shown in Fig. 2, the air traction device 9 consists of a generally cylindrical sleeve body 30 having a transverse wall 31 at one end thereof, said wall having an inlet opening therein. A tubular extension 32 surrounds the opening and extends longitudinally within the sleeve body beyond the lateral opening in the sleeve body through which pressure air is introduced from the compressor 14. At its other end the sleeve body 30 converges into the outlet restriction 13. By reason of the constriction 13 which merges into the outlet pipe 12, the curled strand is caused to build up so as momentarily to obstruct the air flow through the pipe 12. When the air pressure builds up behind the curled fibres to a suitable extent, the portion of curled fibres within the inlet portion 11 of the pipe 12 is forcibly expelled through the pipe 12 and thereby servered from the continuous strand 7. Air under pressure for the operation of the air traction devices 6 and 9 is delivered from a suitable compressor 14 driven by an electric or other motor 15.

The curled portions of fibre are discharged from the outlet pipe 12, as indicated at 7a, to conveyor means, e.g. between upper and lower endless conveyors, such as belts 16, 17 of open-mesh material, the curled fibre portions 7a being sprayed with a suitable binder, e.g. from a nozzle 18. The binder is dried or cured as by applying hot air through distributor heads 19 communicating with branch ducts 20 from a hot air supply conduit 21.

At least a delivery portion 12a of the outlet pipe 12 may be laterally oscillatable for distributing the curled fibre portions 7a on to the conveyor 17. If desired, moreover, two or more units may be arranged side by side in coniun otion with a single conveyor means.

Preferably the distance between the conveyor belts 16 and 17 is adjustable for controlling the thickness of the eventual web or that 22. The density of the Web or mat may be controlled by regulating the speed of travel of the conveyor belts 16, 17. Any density between 0.5 and lbs. per cubic foot can be readily obtained. The type and amount of binder used may be regulated to vary the degree of rigidity of the product which may range from a very flexible mat to a rigid board.

It will be understood that the invention is not limited to the particular embodiments hereinbefore described. For example. instead of a knife edge, any other suitable means may be provided for causing the strand to execute a sharp change in direction for the purpose referred to. Alternatively, any other suitable means may be employed for causing the strand to assume a curled or helical formation and for severing curled portions and delivering them onto conveyor means so as to build up a web or mat.

I claim:

1. Apparatus for forming certain individual monofilaments of a continuously running linear strand of said monofilaments into curled configurations and for successively separating from the continuous strand short lengths of strand containing said curled monofilaments, comprising an air traction device including a generally cylindrical sleeve body having a transverse wall at one end thereof, said wall having an opening therein and a tubular extension surrounding said opening and extending inwardly longitudinally within said sleeve for a portion of the length thereof, said sleeve body having a lateral opening in the wall portion thereof intermediate said sleeve body end Wall and the free extremity of said tubular extension, the wall of said sleeve body converging at its other end into an outlet constriction, and means for passing fluid under pressure through said sleeve body lateral opening, through said sleeve body, and out through said outlet constriction; a deformation element positioned adjacent the inlet opening of said sleeve body; and means continuously feeding the strand of grouped monofilaments first angularly across said deformation element for frictional engagement thereby to cause differential stressing of individual monofilaments of the strand resulting in curled deformation thereof and then into said inlet opening and through said tubular extension, the sleeve body outlet constriction causing intermittent building up of the curled monofilaments to momentarily obstruct the pressure fluid flow through the outlet constriction so that the fluid pressure behind the portion of builtup curled monofilaments will forcibly expel the same through the outlet constriction and simultaneously sever the built-up portion from the following continuous strand.

2. The method of successively severing a continuously running linear strand of monofilaments into short lengths of curled monofilament groups which comprises the steps of drawing the strand across monofilament stressing means to induce differential stresses in the individual monofilaments to form the same into generally curled configurations, causing said curled monofilaments to build up into a group, and applying a fiuid force longitudinally to said built-up group of curled monofilaments to sever the same from said strand.

3. Apparatus as defined in claim 1 wherein said deformation element is a knife edge.

References Cited in the file of this patent UNITED STATES PATENTS 2,230,272 Slayter Feb. 4, 1941 2,313,630 Dockerty Mar. 9, 1943 2,379,824 Mummery July 3, 1945 2,723,215 Biefeld et al. Nov. 8, 1955 2,736,676 Frickert Feb. 28, 1956 2,859,506 Slayter Nov. 11, 1958 2,869,967 Breen Jan. 20, 1959 2,938,256 Bauer et a1 May 31, 1960 FOREIGN PATENTS 558,297 Great Britain Dec. 30, 1943 722,756 Great Britain Ian. 26, 1955

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