DE1303474C2 - DEVICE FOR WELDING AND SEPARATING PLASTIC FOILS ON TOP OF ONE another - Google Patents

Description

The invention relates to a device for welding and separating superimposed Plastic foils with one between two heating bands, whose current flow in its temporal Sequence is controlled, arranged on a cooled carrier, heated separating belt, the end face of the separating tape the level of the end faces of the heating tapes by a little, on the thickness and The degree depending on the softening point of the foils is higher than that according to patent 1,479,821.

Here, plastic film layers are connected to one another by electrically heated sweat bands and at the same time by electrically heated separating belts arranged next to or in between separated. The arrangement of the welding and separating heating tapes is here on a common, cooled welding jaw provided in such a way that said heating bands together or simultaneously be charged with electric current, at the same time a cooling of the to be welded or film material to be separated by adjusting the welding jaws at preferred points takes effect.

Simultaneous or even electrical heating of the welding and separating heating bands During the duration of the process, the use of such devices continues to be simultaneous Welding and separating of plastic foils, however, narrow limits due to the nature of the plastic film material.

The object of the present invention is to determine the period of heat action on the separation point and therefore to control the period of current flow through the relevant heating tape so that in the time the separation point is sufficiently heated and softened after separation, the welding points on the other hand are sufficiently cooled and solidified.

This is achieved according to the invention in that the heating current for the heated separating tape is delayed in time is switched on compared to the heating current for the heating tapes and shortly before the lifting of the Heating tape carrier is switched off.

In addition, it is expediently provided that the separating tape emits a greater amount of heat than one of the heating tapes to the plastic films due to the conductivity and / or the higher electrical voltage applied to it and / or its average measurement and / or the duration of the current flow.

In the drawing, the invention is partially shown schematically on the basis of a preferred exemplary embodiment and is explained below:

The F i g. 1 shows a cross-section through a welding jaw equipped with insulated heating strips, enlarged. On the welding jaw 1, which is

ao nenkühlung 2 is provided, the sweatbands 4 and 5 are attached to an insulating layer 3. A separating band 6 is arranged between the sweat bands 4 and 5 , the end face of which protrudes beyond the heating bands by a small amount. The sweatbands 4

as and 5 are connected together to a pulse generator of a timer, not shown. The separating tape 6 is connected to another pulse generator of said time switch mechanism.

In FIG. 2, the power consumption and thus the heating of the film material is shown schematically for an application example. The time course of the process steps is plotted on the abscissa, while the ordinate shows the current consumption of the heating tapes. According to the example chosen, the welding jaws are closed at time 0 " and thus the beginning of cooling, which is effective over the entire period of the process steps of welding and separating until the welding jaws are opened again at time 2". At time 0 "of the current-controlling timer, the power supply to both sealing strips 4 and 5 also begins. This power consumption 4 ', 5' causes the welding heat to be transferred to the film material. At time 0.5" , the power supply 4 ', 5' is switched off by the time switch ended, while the cooling down by the welding jaw continues in order to solidify the weld seam, which is now finished on both sides.

At time 1, 5 ″ , the timer sends a further heating current pulse to the central separating band 6, which in this example is placed shortly before the welding jaws open, with the heating from current consumption exceeding the cooling effect of the welding jaw at the separating point.

This means that the heated film is not given the opportunity to cool down and solidify at the point of separation.

In this case, the current consumption 6 'of the separating tape 6 is, according to preferred value ratios, approximately 50 to 100 ⁰ O higher than the current consumption value 4' or 5 'of each individual sweatband 4 or 5.

But it can also be done arbitrarily by designing the heating tapes or by dimensioning the current pulses other ratios of power consumption can be achieved and applied.

After the welding jaws are opened at time 2 ″ , the welded film layers therefore tear

at this point between the two weld seams or can be easily pulled off there. the The welding and separating process is thus ended and can be used after the film material has been transported further one production length can be repeated continuously.

The use of welding and separating current pulses

can be set earlier or later depending on the material properties by setting the timer are given and is also variable in the period, so that the device in a simple manner Process steps expedient for processing can be adapted in a wide range can.

1 sheet of drawings DRAWINGS SHEET 1

Number:
Int. Cl .:
German class:
Display day:

B 29 c 27/02 39 a2, 27/02 May 25, 1972

FIG. 1

FIG. 2

Time -—— 000

Cooling down

209 522/258

Claims (2)

Patent claims: 1. Apparatus for welding and separating plastic foils lying on top of one another with a heated separating band arranged on a cooled carrier between two heating bands, the flow of which is controlled in terms of time. according to patent 1,479,821, characterized in that the heating current for the heated separating tape (6) is switched with a time delay compared to the heating current for the heating tapes (4, 5) and shortly before the lift-off Heating tape carrier (1) is switched off. 2. Apparatus according to claim I, characterized in that the separating tape (6) due to the conductivity and / or the higher electrical voltage applied to it and / or its average measurement and / or the duration of the current flow a greater amount of heat than one of the heating tapes ( 4, 5) to the plastic films.