DE3927289C2 - - Google Patents

Description

The invention relates to a method for ver welding of thermoplastic plastic sheets, after the preamble of claims 1, 3, 4 and 6.

The welding of thermoplastic parts with The help of electrical heating wires is used for pipe connections widely practiced. From DE-OS 14 40 958 it is known that Ver plastic sheets with the help of electrical heating conductors can be welded. It is also known that the heating ladder to tapes or networks with the help of thermoplas table support elements to flexible units with the same Heating power per unit area summarized and the heating elements between the overlapping edges of plastic tracks can be installed (DE-OS 14 40 958).

The known welding processes have the disadvantage that with no lasting durability under construction site conditions Welded connections can be made. It is for that required that in addition to the ver even over the welding surface by means of the electrical heating wires conducted heat also an evenly acting contact pressure on the edges of the plastic sheets to be welded brought.

Landfills are sealed according to the state of the art recommended a combination seal consisting of a mineral sealing layer and from plastic sheets put. The thermoplastic plastic sheets are after the installation is welded watertight and should be on the mine ralische sealing layer lie firmly, so that a press bond arises.

The invention includes a method for welding thermoplastic plastic sheets such that the weld can be carried out easily and quickly on the construction site and thereby the press bond between mineral density layer and plastic sheet is produced safely.  

So far, the thermoplastic sheets are on the construction site by extrusion, hot wedge or order the seams are welded together. The Ver welds require a relatively high manual len effort and are therefore time consuming. Because art ver directly on the mineral sealing layer be laid and there the surface of the mineral sealing layer is very sensitive to weather (softening at Re and drying out in the sun) occur on the construction site delays often occur when installing the plastic sheets. In addition, the welding processes previously used require a high qualification of the welding staff.

To protect the plastic sheets and to form waves in follow thermal expansion to avoid sun exposure, the sheets are as short as possible after laying Cover sand or gravel. With the previously applied Welding processes can be difficult to meet this requirement the because of producing a high quality Weld seam on a large area only without interference the gravel / sand paving is achieved. Lying on the construction site the newly laid plastic sheets are often free for several days, so that due to the changing daily temperatures and bulges from the sun's rays. The one in the landfill The desired press assembly is not guaranteed.

The object of the invention is therefore a method for welding thermoplastic plastic sheets find it easily, quickly and safely on site can be carried out and the problems described with Manufacture of the combination seal in landfill construction avoids.

To achieve this object, the invention describes ver different ways to generate the required Contact pressure for welding thermoplastic Plastic sheets with the help of electrical heating wires. According to claim 1, the contact pressure with the help of a Gravel or sand ballast generated after laying the Sheets in the area of the overlapping edges is applied.  

According to claim 3, the overlapping edges of the Plastic sheets in a pressing device, consisting of a press frame as an abutment and a press hose, pressed together.

According to claim 4, the contact pressure by the bring a vacuum between the rän to be welded which creates the plastic sheets.

According to claim 6, the overlapping edges as Lock connection similar to a sheet pile lock like this formed that a tensile and pressure resistant connection is created and the contact pressure is generated with the help of a pressure hose can be.

The application of the contact pressure by means of a vacuum in the Connection with thermoplastic seams Material is already known from DE-34 27 215 A1. However here the vacuum is not directly between the overlapping ones Edges, but outside the welded joint in Suction chambers between the auxiliary pressure beam and the plastic rail nen. Such auxiliary pressure bars have the disadvantage that they uneconomical for very long welds and for sweat connections on differently inclined surfaces like you are unsuitable in landfill construction.

On the attached figures AF he described the invention. Before execution on site, the electrical heating wires ( 2 ) are brought up in the manufacturing plant of the plastic webs on the edges of the plastic webs ( 1 ) (see FIG. A). The edges of the plastic webs ( 1 ) to be welded later can be protected against contamination in the manufacturing plant by applying a film ( 3 ). On the construction site, the plastic sheets ( 1 ) are laid so that the edges to be welded overlap. The protective films ( 3 ) are removed.

Fig. B shows the possibility of generating the contact pressure required for the welding with the help of a gravel or sand load ( 6 ). After laying the plastic sheets ( 1 ) in the area of the weld, a layer of gravel or sand ( 6 ) is applied in the thickness required for the contact pressure. The heating wires ( 2 ) are then heated electrically to the required welding temperature. A heat connection is created between the plastic sheets ( 1 ) using heat and pressure.

Since there is usually one in landfill construction above the plastic tracks Gravel or sand layer is installed, this material for making the weld between the art webs of fabric can be used as described above.

The gravel or sand layer ( 6 ) shown in Fig. B can not be applied with pushers (bulldozers) who because the position of the plastic sheets ( 1 ) in the welding area can be shifted by the thrust. The gravel or sand must be carefully brought onto the plastic sheets from above. For this purpose, sand or screed pumps are suitable, with which the gravel or sand material is conveyed to the installation site via hose lines and is installed there under manual control on the plastic sheets ( 1 ).

As outlined in FIG. B, a double weld seam can be produced by the arrangement of the heating wires ( 2 ). The tightness of the double weld seam can be checked by applying an overpressure in the air gap ( 4 ) between the weld seams.

Fig. C shows the ability to test the pressure required for the welding with the help of a press device. The press device consists of a press frame ( 10 ) with a U-shaped cross section and a press hose ( 11 ) in which the overpressure required for welding is applied. So that the edges of the plastic panels (1) can be loaded device in the press, the edge has a plastic sheet (1) by 180 ° and the edges of both plastic sheets (1) are each folded about 90 °.

The contact pressure required for the welding can also be generated by creating a vacuum between the edges of the plastic sheets ( 1 ) to be welded. For this, an airtight seal between the plastic sheets ( 1 ) must be made to the side of the welding zone. This can be done either by prior sealing welding by means of laterally arranged electrical heating wires ( 9 ) or by the bilateral arrangement of a sealing or adhesive tape ( 8 ).

Fig. D shows a welded connection by means of electrical heating wires ( 2 ) and a gravel or sand load ( 6 ). After the gravel / sand load has been applied, the sealing weld is first carried out at the edges of the welding zone with the help of the outer heating wires ( 9 ). Then a vacuum is created in the air gap ( 4 ) between the outer heating wires ( 9 ), in order then to produce the actual weld seam by means of the electric heating wires ( 2 ).

In Fig. E it is shown how the sealing or adhesive tapes ( 8 ) required to produce an airtight connection are arranged between the plastic sheets ( 1 ) at the edges of the welding zone. The sealing effect is achieved by compressing the plastic sheets ( 1 ) and additionally by applying a vacuum in the air gap ( 4 ), which additionally compresses the sealing or adhesive tapes. After the required negative pressure can be kept in the air gap ( 4 ), the welding takes place by means of heating through the electrical heating wires ( 2 ).

Fig. F shows a certain design of the edges of the plastic webs to be welded ( 1 ). The edges are factory-made so that after assembly, a train and pressure-resistant connection lock similar to a sheet pile lock is created and that inside the lock connection with the help of a press hose ( 11 ) or similar to the contact pressure required for the welding can be generated. The welded connection sketched on FIG. F is particularly suitable for welding thermoplastic sheets ( 1 ) in combination sealing walls. The plastic sheets ( 1 ) are installed vertically in the still liquid sealing wall suspension and the connecting lock is threaded into each other like a sheet pile wall. Then z. B. with the help of the press hose ( 11 ) pressed the inner lock to the outer. The pressure required for the welding can if necessary. suspension should only be applied after the sealing wall has hardened so that the outer lock has an adequate abutment. After heating by means of the electrical heating wires ( 2 ), there is a watertight connection of the plastic sheets ( 1 ) in the sealing wall. The air space in the press hose ( 11 ) can be filled with suspension after welding if necessary.

The described processes for welding thermoplas tables plastic sheets simplify and accelerate the Welding work on the construction site essentially by that preparatory work for welding in the manufacturer be carried out at the factory.

When manufacturing a combination seal in landfill construction can the mineral sealing layer with quickly covered with plastic sheets. The night Any weather influences are minimized. In particular forces the process by applying the Gravel / sand load before welding for quick gravel of plastic sheets. So that the plastic sheets are un indirectly after laying through a layer of gravel or sand protected. A wave formation of the plastic sheets by Tem The effects of temperature and sun exposure are minimized. Between the mineral sealing layer and the plastic sheets the desired press assembly is created.

In the case of a combination sealing wall, the plastic sheets can be welded to one another quickly and reliably after installation in the sealing wall using the overlapping edges ( FIG. F) without using a welding device.

The welding procedures described are on site easy to carry out and require only a small ma effort. The quality of the welded joint is the half less dependent on welding staff.

Claims (6)

1. A method for welding thermoplastic synthetic material webs ( 1 ), in which between the overlapping edges of the plastic webs ( 1 ) electrical heating wires ( 2 ) is built and the overlapping edges of the plastic webs ( 1 ) are welded by heat and pressure, characterized in net that the pressure by means of a gravel or sandfill is produced (6). 2. The method according to claim 1, characterized in that the gravel or sand layer ( 6 ) with the aid of sand or screed conveyor pumps and hose lines is installed. 3. A process for welding thermoplastic plastic sheets (1), wherein inserted between the overlapping edges of the plastic webs (1) electrical heating wires (2) and by means of heat and pressure, the overlapping edges of the plastic webs (1) are welded, characterized in that that the pressure is generated with the help of a press device consisting of a press frame ( 10 ) as an abutment and a press hose ( 11 ) and that for inserting the edges of the plastic webs ( 1 ) in the press frame the edge of a plastic web ( 1 ) by 180 ° or both edges can be folded down by 90 °. 4. A process for welding thermoplastic plastic sheets (1), wherein inserted between the overlapping edges of the plastic webs (1) electrical heating wires (2) and by means of heat and pressure, the overlapping edges of the plastic webs (1) are welded, characterized in that that the pressure between the overlapping edges is generated by applying a negative pressure in the air gap ( 4 ) in the area of the electrical heating wires ( 2 ). 5. The method according to claim 4, characterized in that to generate the negative pressure in the air gap ( 4 ) laterally next to the electrical heating wires ( 2 ) sealing or adhesive tapes ( 8 ) or the outer electrical heating wires ( 9 ) to achieve a seal weld first be heated. 6. A process for welding thermoplastic plastic sheets (1), (2) is built in which electric between the overlapping edges of the plastic webs (1) heating wires and by means of heat and pressure, the overlapping edges of the plastic panels (1) are welded, characterized That the overlapping edges are formed as a plastic lock in one another, such that a tensile and pressure-resistant connection is formed between the plastic sheets ( 1 ) and the required contact pressure for the welding can be generated in the interior of the lock connection with the aid of a press hose ( 11 ).