GB1147364A - Method and apparatus for securing a sieve fabric to a sieve frame - Google Patents

Abstract

1,147,364. Reinforcing edges of non-metallic sheet material. MIAG MUHLENBAU UND INDUSTRIE G.m.b.H. 27 June, 1967 [8 July, 1967], No. 29699/67. Heading B5K. [Also in Division B2] A piece of sieve fabric 6 is secured to a sieve frame 3 by placing the fabric 6 over the frame 3 which is coated on the surfaces contacted by the fabric 6 with an air-dried thermoplastic adhesive, e.g. an adhesive based on polyvinyl acetate, the fabric 6 overlapping the edges of the frame 3; clamping the overlapping edges on at least two opposite sides of the frame 3 substantially along the entire length of the sides; tensioning the fabric 6 over the frame 3 by relative movement in a direction normal to the plane of the fabric between the frame and the clamped edges of the fabric; pressing the fabric 6 against the frame 3 in the regions where it makes contact with the frame ; and heating the fabric 6 in those regions so as to adhere the fabric to the frame. A shown in Fig. 3, the frame 3 is positioned on a base 1 formed with a raised edge. The total thickness of the adhesive coating on the frame 3 may be substantially equal to the thickness of the sieve fabric and this coating may be formed of a number of individual layers each dried before application of the next. Resilient foam rubber cushions 5 are accommodated in free zones of the frame 3 and their upper faces project above the frame 3. The rectangular fabric 6, which may be of polyamide fibres, is pre-soaked in water and placed on the frame 3 whilst dripping wet so that it becomes partly tensioned as it shrinks as it dries. Clamps 8 are pressed together to grip the fabric 6 and are moved downwardly in the direction of arrows 9 to tension the fabric, pressure plates 51 having been placed on each field of the fabric 6. A vertically guided section 10 is lowered so that plates 11 thereon formed with longitudinal channels and heated to above 60‹ C., e.g. about 130‹ C., engage the frame 3, for example, for ten seconds, to soften the adhesive to adhere the fabric 6 to the frame 3. After removal, the edges of the fabric projecting from the frame 3 are cut off. In apparatus for performing this method, Fig. 5, four pairs of clamps 8 are provided, the lower clamp of each pair being fixed to a frame 15 adjustable in height and the upper clamp being secured to a bell crank 16 pivotable about an axis 18 by an hydraulic ram 17. The clamps 8 are preferably of an undulating cross-section without sharp edges to facilitate gripping. The base 1 is raised and lowered by a member 21 eccentrically mounted on an actuating shaft 20. The section 10 is mounted on a piston rod of an hydraulic cylinder 22 displaceable on horizontal rails 24. Electrical elements 25 are provided to heat the plates 11 which are coated with a parting agent.