DE1082686B - Process for the purpose of welding foils by means of dielectric high-frequency heating - Google Patents

Description

In the current state of the art, the operations in welding foils are made of thermoplastic Materials using high frequency dielectric heating similar to those used when sewing with the sewing machine. So far, they were also set about the same limits.

This working method for the manufacture of high frequency welded Seams with the previously known means fail when it comes down to the fact that not all foils in a stack of foils, but only some of them should be welded. With this one for high frequency welding The present invention is concerned with a new problem.

The desire to realize this possibility arises in many cases because one is through union several operations that were previously carried out one after the other in a certain order had to, to a work step faster and less cumbersome, so much more economical can work. Often times, the existence of this possibility is even necessary because the work products cannot be produced with the known methods or cannot be produced in the desired form. in the The following is a closer look at this with the help of examples.

Attachment pockets of lined briefcases, for example, compartmentalized pockets and similar items, in which partial seams are present, can indeed be achieved by partial assembly welding in several Establish operations. A production in one operation would be economical and work-related reasons highly desirable. Should such a bag also be provided with an attachment loop that has the full width of the bag passage, so it is with Partial assembly welding is no longer possible because a weld seam must run under the loop.

Similar cases exist when a workpiece is to be turned inside out after welding weld off the rolled up seams. Has one z. B. a sleeve of a raincoat initially simply welded, turns it inside out, in order to now weld the seam edges down, so you have to, if only the means known up to now are available for this purpose, very complicated facilities - for example, a roller electrode attached to a mandrel - use that only more or less allow short welds.

Also think of the welding of the longitudinal seam of stockings.

Such methods fail in any case with hose diameters that are smaller than necessary Mandrel diameter, and for hoses that are very long.

Process for the purpose of welding foils by means of dielectric

High frequency heating

Applicant: Standard Elektrik Lorenz

Corporation,

Stuttgart-Zuffenhausen,

Hellmuth-Hirth-Str. 42

Dipl.-Ing. Tankred v. Hauteville, Stuttgart-Degerloch, has been named as the inventor

In the case of the welding press, too, difficult problems have arisen up to now with tasks of this kind. The counter electrode had to have a free passage and could only be clamped at the ends. The free The standing electrode had to be sufficiently stable and have enough space to accommodate the To be able to pull the entire length of the hose between its supports.

These described circumstances can be circumvented if, according to the invention, for the purpose of welding together only certain foils of a foil package through intermediate layers, preferably made of metal, the welding together of the not to be welded Foils is prevented.

The mode of action of these intermediate layers can be different. First and foremost, however, it is intended to that the distance between the welding electrodes through at least one intermediate layer made of metal in a Series connection of capacities of different sizes is divided, of which the smallest resp. smallest serves or serve the purpose of welding.

A simple example of this is given in FIG. 1, in which only two of four foils are welded together should be. Between the two electrodes of different widths 1 and 2, for example Roller electrodes, four foils 3, 4, 5 and 6 made of thermoplastic material are mounted. The liner 7 is here between the foils 4 and 5. In this way it is achieved that the capacity between 2 and 7 is greater than between 1 and 7. If the high frequency energy is properly dosed, then a fusion of the foils 3 and 4 occur, while the foils 5 and 6 do not be welded.

The shape of the washers can be largely adapted to the intended use.

009 528/246

In many cases it will be convenient to use them as a Execute foil tape made of metal, the thickness of which can be very small. However, the width must be in this Trap larger than the weld.

An intermediate layer with a trapezoidal or T-shaped cross section has also proven to be particularly useful proven, the narrower side of which corresponds to the width of the seam to be welded.

An application example is given in FIG. 2 in which partial welds are carried out within a foil package are executed. The nine foils 8 to 17 are arranged between the electrodes 18 and 19. Between slides 8 and 9., 10 and 11., 12 and 13 as well as 14 and 16 are each band-shaped intermediate layers 20, 21, 22 and 23 arranged, of which 21 and 22 have the described T-shaped shape. The narrow sides of these two intermediate layers correspond to the Width of the weld seam. The lowest capacities within this package are apparently between the Intermediate layers 20 and 21 as well as 22 and 23, so that only one welding of the foils 9 with each 10 and 13 enter at 14.

To guarantee the correct position of the intermediate layers with a T or trapezoidal cross-section, you can the same with lateral retaining pins or strips 24 according to FIG. 3 from appropriate Material provided. If these retaining pins or strips are made of metal, then of course they are not allowed to be used Counter electrode made of metal are assigned, which has the width of the intermediate electrode according to FIG. 3.

In other applications it will be advantageous to use intermediate layers that are not made of metal are. Here, the electrical high-frequency field will penetrate the entire stack of foils almost homogeneously, as is the case in Fig. 4, wherein between electrodes 25 and 26 four are partially interconnected foils to be welded 27 to 30 are stored. There is one between the foils 28 and 29 Intermediate layer 31 made of a material, preferably with a very high dielectric constant and if possible small tg (5 value. In this case, the foils 27 with 28 and 29 with 30 are welded instead of. With such an intermediate layer 29 can even be a squeezing of the field and thus achieve an increase in the welding effect. However, this intermediate layer must not be wider than the Be welded because of the necessary sinking of the electrodes during the welding process.

Such materials with a large dielectric constant and a small tgd value tend to be very poor To be a conductor of heat. So if the process of welding doesn't go fast enough, you can a considerable heating of these intermediate layers occur. In many cases this is undesirable (e.g. when flattening an embossing). In other cases, metal spacers must be used in the manner described use, which also have the advantage of better machinability.

To make it easier to place the various intermediate electrodes on top of one another and prevent them from slipping avoid, these can also be made of magnetic material with high coercive force and remanence will.

All the methods described are suitable both for the welding press and for use between roller electrodes, which are used for high-frequency welding.

Reference should be made here to a particularly expedient arrangement, which is shown schematically in FIG. 5 Way is shown. It is particularly suitable for welding hoses of limited length, for example the sleeves of raincoats made from foils of thermoplastic material. The intermediate layer 32 (Fig. 5) extends out of the hose end on both sides. At these ends are, for example attached by brackets, strips 33 and 34, on the one hand the holder of the weld metal 35 and on the other hand serve as a guide rail for the machine-fixed guide rollers and in this way the Provide the ability to weld a very clean and straight seam.

Claims (8)

PATENT CLAIMS: 1. Process for the purpose of welding foils by means of dielectric high-frequency heating, characterized in that for the purpose of welding together only certain foils a foil package by means of intermediate layers, preferably made of metal, the welding together of the foils that are not to be welded are prevented. 2. The method according to claim 1, characterized in that the distance between the two Welding electrodes through at least one intermediate layer made of metal in a series connection of Capacities of different sizes are divided, of which the smallest or smallest dem Purposes of welding serves or serve. 3. Device for performing the method according to claim 1 and 2, characterized in that that the intermediate layer is a very thin foil strip that is wider than the weld seam, is executed. 4. Device for performing the method according to claim 3, characterized in that that the cross-section of the intermediate layer is trapezoidal or T-shaped and that the narrower side is about the The width of the seam to be welded. 5. Device for performing the method according to claim 4, characterized in that that the trapezoidal or T-shaped intermediate layers with lateral retaining strips or pins made of appropriate Material are provided. 6. Device for performing the method according to claim 3 to 5, characterized in that that as an intermediate layer dielectric materials preferably high dielectric constant and small tg <5 values can be used. 7. Apparatus for performing the method according to claim 3 to 5, characterized by using magnetic material, preferably high coercive force and remanence as an intermediate layer. 8. Apparatus for performing the method according to claim 1 and one of the preceding Claims, in particular for welding hoses of limited length, for example Sleeves of raincoats, characterized in that the intermediate layer on both sides of the Hose end 'extends out and attached to these ends, for example by clips, such strips are, on the one hand to hold the weld metal and on the other hand as a guide rail are suitable for the machine-fixed guide electrodes. 1 sheet of drawings © 009 528/246 5.60