DE3132273A1 - METHOD AND DEVICE FOR WELDING THERMOPLASTIC RAILWAY MATERIAL - Google Patents

Description

description

The invention relates to a method and a device for welding thermoplastic material and in particular for welding thermoplastic webs according to the preamble of the main claim.

The lap welding of thermoplastic sheets or strip, superposed on the superposed edges or -J ₀ surfaces to be welded, is generally carried out in the following manner:

a) The surfaces are heated to a higher temperature than the melting temperature by means of a heated metallic wedge heated, which is moved over this. The melted surfaces are then pressed together as long as until the material has cooled down again below the melting point and thereby solidified.

b) The surfaces are heated by means of a preheater to a temperature which is usually below the Melting point is. In order to ensure correct melting of the webs for welding, a additional heat is added by adding more molten thermoplastic material in sufficient quantity Amount at a sufficient temperature

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is set to ensure the melting of the web surfaces to be connected. The faces are then pressed together so that the welding takes place on cooling below the melting point.

In the known method, the heat for melting and / or for preheating on the following known ways:

-IO i) ^A hot metal wedge is used, to which heat is supplied by conduction. The heat source is usually an electrical component, a flame or a hot gas stream.

• ^ 5 ii) The heating takes place with the help of a hot Gas or air jet, which is usually caused by an electrical component or by a flame is heated.

iii) The heat is transferred by radiation, usually in the infrared range, es however, other wavelengths are also known.

To ensure a constant welding temperature in cases (ii) and (iii) to ensure it is necessary to maintain the temperature of the thermoplastic to be welded

Measure tracks and regulate the heat supply to compensate for temperature fluctuations. However, temperature measurements take no account of others Factors such as moisture remaining on the webs that require additional heat for evaporation, whereby the surface temperature is lower than necessary.

To ensure a constant welding temperature in cases in which the hot wedge touches the tracks, what applies to cases (a) and (i), it is sufficient, the temperature of the wedge as close as possible to the Measure working surface of the wedge and temperature fluctuations compensate by regulating the heat supply. However, since this supply of heat does not occur suddenly there is a time delay that can lead to uneven welds.

Another difficulty with the known welding / joining method (a) occurs when the seam must be both mechanically sound and tight. If the edges of the webs to be connected are not absolute are even, small folds of material form in front of the Welding wedge. These folds occasionally run over the welding wedge and remain unwelded, so that a Fluid channel is created.

In contrast, it is the object of the invention to provide an improved To provide a method and apparatus for welding thermoplastic sheet material, which do not have the disadvantages occurring in the prior art.

The measures specified in the characterizing part of the main claim serve to solve this problem.

- ^ q The invention thus relates to a method for welding of thermoplastic sheet material, which is characterized in that two to be welded Lanes are placed with their edges on top of each other, leaving a hot wedge between the overlapping ones

-I5 edges to touch the adjacent faces of the two Sheets are pushed and heated to a temperature high enough to melt both surfaces, that molten thermoplastic material is introduced between the superimposed edges is, and that the superimposed edges are pressed together and cooled, whereby the surfaces through the thermoplastic material of the webs completely connect with each other and any gaps or folds are filled by the additionally introduced thermoplastic material.

The additional thermoplastic material is preferably placed between the overlapping edges in one place introduced, which is close to the surfaces melted by the hot wedge.

Preferably, a hot wedge is used to weld

superimposed edges of thermoplastic webs, which consists of a material suitable for this and which can be _{heated by means of a controllable induction coil ^ 0} or a similar device.

In particular, the hot wedge has a resistance heat tion as well as means to introduce a large current of low voltage into the wedge.

Furthermore, in a preferred embodiment, a temperature sensor is provided which is used to control the heating device serves for the wedge.

It is therefore a new method of welding created by superimposed edges of thermoplastic sheets, which by means of a hot wedge, the Temperature can be easily and precisely regulated, creates very good and watertight seams.

The invention is illustrated below with the aid of three exemplary embodiments explained in more detail. In the figures show:

Figure 1 is a schematic view of a first embodiment, with superimposed webs of thermoplastic material through a wedge to be connected;

FIG. 2 shows a second exemplary embodiment;

Figure 3 shows a third embodiment in which to
additional thermoplastic material incorporated
is brought; and

Figure 4 shows a fourth embodiment.

Figure 1 shows a first embodiment in which adjacent surfaces 1 and 2 of one above the other Edges 3 and 4 of two sheets of thermoplastic material joined together by means of a hot wedge 5 will. The hot wedge 5 is heated by an externally arranged induction coil 6.

The hot wedge 5 is moved between the surfaces 1 and 2 in the direction of the arrow X. While he's in that direction is moved, it melts the surfaces 1 and 2, the

are then pressed against one another by means of a roller 7. In this way, the molten material of the surfaces 1 and 2 is brought into contact with one another and solidified when the webs cool below the melting point, causing the webs to weld together.

To control the temperature of the hot wedge 5 is used a temperature sensor 8 as close as possible to the Tip 9 of the wedge 5 is housed. This tempera .JQ ture sensor 8 is connected to a controller, not shown connected, which regulates the induction coil 6 heating the hot wedge 5. ■

Figure 2 shows a second embodiment in which ^ c two webs of thermoplastic material on the same way as in the first embodiment with each other but a different type of wedge 10 is used. The hot wedge 10 has the shape a sheath 11 made of suitable resistance material. These Sheath 11 is connected with its ends 12 and 13 to electrical lines 14 and 15. About these Lines 14 and 15 are fed a high current of low voltage, causing the hot wedge 10 to open heated to a desired temperature suitable for welding.

As with the previous version, there is a temperature sensor 16 arranged in the vicinity of the tip 17 of the wedge 11. The temperature sensor 16 regulates the through the current flowing through the wedge 11 in a known manner and thus controls the temperature of the hot wedge 10.

In the aforementioned embodiments, a small amount of additional molten thermoplastic material between the surfaces 1 and 2 after -J may be ₀ whose melting be inserted through the wedges 5 and 10, but prior to the pressing by the roller 7, respectively. A nozzle 18, for example, which is arranged in the vicinity of the tip 19 of a wedge 20 shown in FIG. 3, is used for this purpose.

As the roller 7 presses the two webs together, their molten surfaces 1 and 2 come together in touch . The additional molten thermoplastic material collects in any resulting Clearances or folds in which the two surfaces 1 and 2 are not welded together and This ensures a flawless, completely closed weld seam.

One cause of such folds, which can lead to leaks in the weld seam, is shown in FIG.

While the two tracks move under the roller 7, A small wave of material often forms in one of the paths in front of the roller 7. These waves run sometimes through the bottom of the roller 7 and form a fold 21. However, the additional material 22 collects in such folds 21 and closes them on .die previously described way.

Another embodiment of the invention is shown in -JO Figure 4 shown. Instead of bringing in of additional thermoplastic material in the area between the wedge tip and the pressure roller this material introduced laterally to it. While the roller 7 presses the surfaces 1 and 2 against each other, collects the additional thermoplastic material in shape a seam 23 next to the welded surfaces and thus seals any leaks or gaps that may have arisen. In doing so, the heat of the additional molten material used to melt the surfaces 1 and 2 and thus causes a Similar welding as in the other exemplary embodiments.

HU / lU / where

Claims (5)

US = XKUi-L & "5TOl-BERG PAl t. N IANWAI I E BESELERSTRASSE D-20CO HAMBURG 1;" Hl) I1I ΛΙ; I '.Vl I NI; |. '!.' Ni DR JD FRHR by i_ EXKULL DR ULRICH GRAF STOLBERG DlPL ING JÜRGEN SUCHANTKE DIPL-ING- ARNULF HUBER DR ALLARD by KAMEKE DR KARL HEINZ SCHULMEYER Gundle Holdings (Proprietary) Limited 1st Avenue, Elma Park, Edenvale, Johannesburg : Aug. 22, 1980 ZA 80/5190 (17910 HU / lü / wo) August 1981 Method and device for welding thermoplastic web material Patent claims 1.) A method for welding thermoplastic web material, characterized in that - that two webs to be welded are placed with their edges (3, 4) on top of each other, - That a hot wedge (8,20) between the overlapping edges (3,4) for contact with the neighboring Areas (1,2) of the two tracks are pushed and heated to a temperature that is high is enough to melt both surfaces (1,2), • "* - <■ « m v - That molten thermoplastic material is introduced between the overlapping edges (3, 4) will, - and that the superimposed edges (3, 4) are pressed together and be cooled down, thereby completely connect the surfaces (1,2) to one another by means of the thermoplastic material of the webs and any gaps or folds from the additionally introduced thermoplastic material - JO rial to be filled out. 2. The method according to claim 1, characterized in that that the additional thermoplastic material in the part of the area melted by the hot wedge (8,10,20) chen (1,2) is introduced. . 3. Wedge for welding superimposed edges of thermoplastic sheets, characterized in that that the wedge (8,10,20) can be heated by an induction coil (6), that means for Regulation of the induction coil (6) are provided, and that means are provided to a strong To allow low voltage current to flow in the wedge (8,10,20). 4. Wedge according to claim 3, characterized by a temperature sensor (8) for controlling the heating device (8,10,20). 5. wedge according to claim 3 or 4, characterized by Means (18, 19) for introducing additional molten plastic between the superposed Edges (3,4) after the hot wedge (8,10,20) has passed, and through devices for pressing the superimposed edges (3, 4) together after the molten material has been introduced Plastic.