METHOD FOR MANUFACTURING A HEATING MAT

Description

[0001] The present invention relates to a method for producing a heating mat.

[0002] There are a wide variety of heating mats available for numerous different applications.

[0003] Such heating mats typically consist of three layers: a lower layer made of a flexible material, such as rubber or similar, a middle layer consisting of a thin-bed heating mat similar to that used for electric underfloor heating, and a top layer, which, like the lower layer, also consists of a flexible mat. These three layers are glued together, and the thin-bed heating mat is connected to a power cable, which may also include an integrated thermostat.

[0004] Such heating mats have the disadvantage that they are relatively inflexible due to their three-layer structure and can only be rolled up with a large radius, which prevents the heating mat from being stored in a space-saving manner when not in use.

[0005] If you try to roll up such heating mats with a smaller radius, there is a risk that the glued layers will separate from each other, which will hinder the use of the heating mats.

[0006] Such three-layer heating mats are also relatively thick, which increases their weight.

[0007] WO 2011 / 126223 A2 and US 4 459 461 A each disclose heating plates in which a heating wire fixed to a fabric is laminated by an extrusion machine in order to enclose it between two polyurethane layers.

[0008] In US 6 172 344 B1, an electrically conductive fabric is also cast between two polyurethane layers.

[0009] The object of the present invention is to provide a method for producing a heating mat which is low in height, yet durable and has a high degree of flexibility, so that it can be easily rolled up and does not pose a tripping hazard during use due to its low height.

[0010] This object is achieved by a method for producing a heating mat having the features of patent claim 1.

[0011] Subclaims are directed to preferred embodiments of the method according to the invention.

[0012] In the following, the present invention is explained in more detail by means of the description of an embodiment with reference to the drawing.

[0013] Showing: Fig. 1 a thin-bed heating mat, laid out on a flat, smooth surface with already taped side borders, and Fig. 2a thin-bed heating mat already cast on one side on the flat, smooth surface.

[0014] In the method according to the invention for producing a heating mat, a coarse-mesh fabric is first cut to the appropriate size, usually rectangular, and laid out on a smooth, flat surface. The base is usually one or more PE plastic sheets. The fabric can be made of an elastic plastic or rubber with a mesh size of around 1x1 cm, such as those used as anti-slip mats under carpets on smooth floors. It can also be a textile fabric with the same mesh size.

[0015] A heating wire is then laid out in a meandering pattern and fixed or sewn to the fabric with a coarse mesh. This creates a so-called thin-bed heating mat, which can be easily glued to the base to prevent it from slipping.

[0016] Then, to define the peripheral edge of the heating mat, a trim cord adhesive tape is glued to the flat base and / or the fabric.

[0017] A trim cord tape, such as one sold under the brand name WireTrim, has a standard adhesive side and a non-adhesive backing, to which a trim cord or trim wire is glued lengthwise in the center. The trim cord or trim wire can be made from extremely thin, tear-resistant fishing line or steel wire with a very small diameter. The trim cord tape is used to define the final dimensions of the heating mat, and the area outside the thin-bed heating mat is covered, for example, with paper, to prevent unnecessary soiling of the PE plastic panels.

[0018] Liquid polyurethane is then sprayed onto the fabric to extend beyond the trim cord tape.

[0019] After the applied polyurethane layer has cooled, the trimming cords or trimming wires are removed, resulting in accurate edges on the semi-finished heating mat.

[0020] Then, in the next step, the half-finished heating mat is removed from the base and turned over.

[0021] The back is also coated by spraying polyurethane and trimmed in the same way as the front or, since the current back is already properly contoured, trimmed with a carpet knife or similar.

[0022] The resulting finished heating mat can have a thickness between 4 mm and 6 mm, which is very thin compared to conventional heating mats.

[0023] The installed heating wire should be a bare, sheathed or varnished wire strand with a thickness of at least 3 mm.

[0024] The spray-cast polyurethane is a product marketed under the name Rhino Skin ®<.

[0025] A textured, double-sided surface for slip resistance is a hallmark of rhino hide. This slip resistance can be further enhanced by sprinkling granules.

[0026] Holes can be drilled in the corners and / or along the side edges of the heating mat to screw the heating mat to the surface.

[0027] The heating mat produced in this way can be manufactured in a wide variety of sizes. This allows heating mats to be installed under office desks and in unheated workshops for workplace heating, in food trucks, in outdoor areas of restaurants to keep ice free, to heat the steps of fire and escape stairs, and to keep ice free in sewage treatment plants, etc., all of which can be customized to meet specific needs.

[0028] Another practical use is for narrow, long heating mats as seating in unheated churches.

[0029] Furthermore, there are hardly any limits to the imagination when using such inventive heating mats.

Claims

1. A method of manufacturing a heating mat (9) comprising the following first step: - sewing a heating wire (1) with supply leads onto a fabric (2) to form a thin-bed heating mat (4), characterised by the following further steps: - adhering the thin-bed heating mat (4) to a smooth, flat base (3), - fixing the circumferential edge of the heating mat (4) by sticking a trimming cord adhesive tape (5) onto the flat base (3) and / or the fabric (2), - spray-moulding of polyurethane on the fabric (2) up to over the trimming cord adhesive tape (5), - allowing the polyurethane layer applied in this way to cool, pulling off the trimming cord from the adhesive tape (5) by cutting through the polyurethane layer, - detaching the thin-bed heating mat (4), which is moulded on one side, from the flat base (3) and turning it over; - spray-moulding of polyurethane on the turned thin-bed heating mat (4) which has been moulded on one side, - cuting off any polyurethane protrusions that may have formed, which project beyond the edge defined by the trimming cord.

2. The method for producing a heating mat (9) according to claim 1, characterised in that the spray-moulding is carried out at a high material flow under low spray air.

3. The method according to one of claims 1 and 2, characterised in that the heating mat (9) has a thickness of 4 mm to 6 mm.

4. The method according to one of the preceding claims, characterised in that the heating wire (1) has a thickness of at least 3 mm.

5. The method according to claim 4, characterised in that the heating wire (1) is a bare, a coated or an enamelled stranded wire.

6. The method according to one of the preceding claims, characterised in that the flat, smooth base (3) is composed of PE plastic sheets.

7. The method according to one of the preceding claims, characterised in that the spray-moulded polyurethane is a product marketed under the name Nashornhaut®.

8. The method according to one of the preceding claims, characterised in that holes are made in the region of the corners and / or along the side edges of the heating mats for screwing the heating mat (9) to the floor.