SU979136A1 - Apparatus for heat-pulsed welding of polymeric films - Google Patents

Description

The invention relates to the field of welding plastics and can be used in packaging technology.

A device for thermopulse welding of polymer films is known, which contains a heating element in the form of an electrically conductive strip, a dielectric base and a clamp.

The use of this device in packaging technology is difficult in the manufacture of bags from polymer film sleeves with their simultaneous filling with plastic, semi-liquid or liquid material, especially in those cases when full filling of the volume of packages with the material to be packed is required. This is due to the fact that the packaged material in the package stretches the weldable films in the seam zone, as a result of which the latter, under the influence of a thermal impulse in flowing state, are separated, destroying the seam.

A device for thermo-pulsed welding of polymeric films is known, which comprises a heating element mounted on the base, made in the form of an electrically conductive strip and a clamp with a cushioning gasket 2.

A disadvantage of the known device is that the electrically conductive strip has a central protrusion

10 along its longitudinal axis and two lateral protrusions formed on the bent edges of the strip parallel to the central protrusion. The side projections are rounded, and their height is not more than half

15 height of the central protrusion.

Claims (2)

The rounded protrusions on the bent edges of the electrically conductive strip provided for pressing the 20 films to be welded and reducing the tensile forces in the weld zone do not ensure a high-quality weld. This is due to the fact that during welding, the protrusions mounted on the basis of an electrically conductive strip and a cushioning gasket are pressed between the protrusions, the polymer films in the weld zone are heated to a viscous flow state, and from the packed material at the same time tensile forces act, and as a result, the polymer films to be welded begin to flow in the seam area. The rounded protrusions on the bent edges of an electrically conductive strip reduce the tension of the films to be welded in the central zone of the seam, but do not provide complete protection against damage to the heat-affected zone. The aim of the invention is to improve the quality of the connection by reducing the tension of the films to be welded in the weld zone. This is achieved by having a heating element mounted on the base, made in the form of an electrically conductive strip, and a clamp with a cushioning pad, according to the invention. and the clamp is provided with pneumatic pumps, made as installed symmetrically with respect to the heating element on the base and the clamp is coarse with openings on the outside x cylindrical 1 surfaces fixed with the possibility of rotation around their longitudinal axis. In the drawing, the cross section of the proposed device is shown. The device comprises a base 1 with a heating element 2, insulated with two layers 3 of insulating heat resistant non-sticky material, for example, a varnish-cloth with a friction coefficient, a pressure 5 with a damping pad 6 covered with one layer 7 of the same insulating material and pneumatic convectors View of tubes 811 with openings 12-15, 1 on outer cylindrical surfaces of tubes 8-11. Tubes 8-11 are crushed respectively on the bases of viii / 1 and clamping the heater symmetrically. This element 2 is on both sides with the ability to turn wok-arms of its gauge axes. Inside the base t, a hole 1b for cooling is made parallel to the heating element. common fluid. The device works as follows. 1364 Polymer films 17, 18 to be welded are compressed between the heating element 2 mounted on the base 1 and the clamping cushion 6 of the pressing 5 covered with insulating layers of heat-resistant non-stick material and 7. By turning on the electric current the heating element 2 made in the form of electrically conductive strip with longitudinal the protrusion is heated to a certain temperature, as a result of which the polymer to be welded is heated)) 1e to a c, co-flowing state. Simultaneously with the compression of the films being welded, before switching on the electric current, a vacuum is connected to the tubes 8-11, under the action of which the weldable film 1/7 18 through the holes 12-15, made on the cylindrical surfaces of the tubes 3-11, stick to them. In this case, tubes 8-11 rotate each way so that the films to be welded in the area of the seam are released from tensile forces. At the end of the heat pulse, the welded films 17, 1B remain compressed between the heating element 2 and the damping of the pressing pad 6 of the clamp 5 until the joint is formed and cooled, then the vacuum is disconnected, when 5 is removed from the base 1, 11 rotates to the source position. M The invention allows to obtain reliable and high-quality seams when packing viscous, semi-liquid and liquid materials into packages from a polymeric sleeve with full use of the package volume. In turn, the rational use of the volume of the pas of the sets allows the savings of the hectare of the nighttime polymeric material, c. The invention The device for thermo-impulse. uvarki polymer films, containing a heating element that is bmsteated on the base, made in the form of; Electrically conductive strips, and clamp, p. cushion gasket, o t, and, in order to improve the quality of the connection, by reducing the tension of the weld. The films of the films in the seam area, the base, are equipped with pneumatic pumps, which are 59791 filled as installed symmetrically with respect to the heating element on the base and the pressure of the tubes, with openings on the outer cylindrical surfaces, fixed s rotatably around their longitudinal axis. 6 Sources of information taken into account during the examination 1. USSR author's certificate No. 190551, cl. B 29 C 27/02, 1965. 2. USSR author's certificate ff 52651, cl. In 29 C 27/02, 1975 (prototype).