This invention relates to an apparatus for the manufacture of a flexible heating appliance, comprising at least one heating wire constituting an electrical heating circuit being placed between textile materials which are combinable with each other thermally, directly or with the aid of an additional adhesive layer, and combining the said textile materials by the application of heat and pressure.
Flexible heating appliances of the aforesaid kind have been known, for instance, from German Pat. No. 1,757,215 which provides for inserting heating conductors into woven-in channels in a textile fabric .In part, the heating conductors are already woven-in or are received between weldable, channel-forming layers, while the welding process itself is carried out by special high-frequency welding tools devised for this type of manufacturing method.
A simple method of fixation comprises the use of coated fabrics, webs or fleeces which are combinable in flat shape with each other, in the manner used in making outer wear or over-clothes. It is furthermore known to provide grooves or similar recesses in an ironing plate or ironing board, into which grooves the heating conductor being placed on the underneath layer, is pressed during the ironing treatment, so that there is no combination such as by welding in the zone of the groove or the like recess, and the heating conductor remains displaceable in the channel system being formed. Within the program of a further development of flexible heating bodies which can be used for heating seats, and in particular automobile seats, it was necessary to achieve a short heating-up period in order to provide a satisfactory heating of the seat surface, if possible within a very short time. A prerequisite for attaining this goal is an inherent softness of the flexible heating body which latter must lie directly under the cover material of the seat, while the heating circuit design must not become contrasted on the surface of the cover material.
For this purpose, thin heating conductors insulated with coatings having the properties of perfluoropolyethylenes such as Teflon, and whose diameter is smaller than 2 mm, have been sewn on to a lower layer of material, and have then been additionally affixed in position by covering layers of material being joined to the layer underneath by ironing. The layout in an ironing plate mentioned hereinbefore can be carried out much more rapidly, but it is necessary to this end that the nails which determine the layout of the heat carrier and its bends are depressable in grooves to be preferably flush with them during the ironing treatment.
Both of these known methods are expensive, as a lack of fit between the ironing plate and the nail template or stencil may cause serious damage to the template.