GB857144A - An improved method of and depositor for forming reinforced plastic articles - Google Patents

Abstract

<PICT:0857144/III/1> <PICT:0857144/III/2> <PICT:0857144/III/3> A fibre-reinforced plastic article is made in a continuous operation by cutting fibre roving into predetermined lengths, separating the lengths of roving into their constituent strands, suspending the strands in a stream of air, coating the strands with a bonding plastic material and projecting the coated strands, in an organised directable stream, on to a mould or form. The roving is a rope-like material of e.g. 30 or 60 strands each strand being made up of e.g. just over 200 glass fibres or filaments. The plastic material is a synthetic resin, e.g. an alkyd polyester. As shown, a self-feeding rotary cutter 20 is mounted on and driven by a compressed air motor. Roving is directed through a guide plate 24 and thence between two feed rollers 66 and 68 into one side of the cutter whereby the roving is cut into short lengths which are ejected from the opposite side of the cutter. The compressed air motor is contained in a casing 34 which may also serve as a handle for the apparatus. Mounted on the upper end of the casing is the cutter frame 30, which comprises a lower body 40 having an extension 41 threaded on to the casing and a top plate 42 bolted on to the lower body. The cutter 20 comprises two cylindrical rollers 45 and 46; the shaft 48 of the driving roller 45 is driven directly from the motor, roller 46 is driven by frictional contact with roller 45. The driving roller 45 serves as the cutting cylinder and is provided (see Fig. 7) with blades 55 mounted between segments 56 and in accommodating slots in a sleeve 58 fixedly mounted on the shaft 48 and secured therein by rings 59 embedded in the opposite ends of the segments 56. The driven roller 46 comprises a relatively hard outer sleeve 60, e.g. of nylon, having a corrugated surface, mounted on a relatively flexible inner core 62, which is sufficiently elastic to permit the passage of tangled roving, but sufficiently rigid to enable the cutter blades to sever the roving. The core 62 can be made of compressible material e.g. sponge rubber, or as shown a solid rubber core 62 is mounted centrally on shaft 50 and positioned by lips at either end of the shaft. The sleeve 60 is supported at its end and central portions only, so that annular spaces 64 are left between the sleeve and core. Roving enters the cutter through three wide holes 82 (only one shown in Fig. 4) in the plate 24 and passes between rollers 66 and 68, which consist of rubber sleeves mounted on comparatively heavy steel shafts. Roller 66 is mounted on a shaft which extends through the body 44 and has a knurled wheel mounted on its lower end for manually rotating the feed rolls. The middle portion 85 of the body 40 is arcuately shaped and has a hollow interior 86 communicating with the motor exhaust ports 88 in the upper part of the casing 34 through a passage 90, holes 92, and an annular chamber 94 in the extension 41. Along the edges of the body 85 are holes forming the jets 28 venting chamber 86 to atmosphere, so arranged that converging air streams are directed at the cut lengths of roving emerging from the cutter and separate them into their component strands. Holes are also arranged in four lines on the inside wall of body 85 at 116 to form air streams directed on to the cutter and feed rollers to remove fibre fuzz therefrom. The two spray guns 32 are mounted on opposite sides of the apparatus, are operated by compressed air, and emit converging jets of liquid plastic which intersect in front of the cutter and coat the separated strands of the cut roving. A mixture of plastic and catalyst may be supplied to one of the guns, and a mixture of plastic and accelerator to the other, the three materials being so chosen that the two binary mixtures are relatively stable but the ternary mixture sets rapidly.