WO2016055471A1

WO2016055471A1 - Method and device for joining two material layers by means of high-frequency welding

Info

Publication number: WO2016055471A1
Application number: PCT/EP2015/073039
Authority: WO
Inventors: Andreas Foistner; Werner Prossliner
Original assignee: Conti Temic Microelectronic Gmbh
Priority date: 2014-10-07
Filing date: 2015-10-06
Publication date: 2016-04-14
Also published as: DE102014220211A1; DE102014220211B4

Abstract

The invention relates to a method for joining two material layers (10, 20) by means of high-frequency welding. In said method, the two material layers (10, 20) are placed on top of each other to form a material arrangement such that the end-face ends (11, 21) thereof have a pre-determined lateral distance (30) to one another. The material arrangement is introduced into a joining device (40) such that the region of the end-face ends (11, 21) of the arrangement comes to rest between a first welding electrode (41) and a second welding electrode (42) of the joining device (40). The end-face end (11) of the first material layer (10) comes to rest between the respective opposite front surfaces (43, 44) of the first and second welding electrode (41, 42). The end-face end (21) of the second material layer (20) comes to rest outside of the respective opposite front surfaces (43, 44) of the first and second welding electrode (41, 42). The joining process is then carried out, as a result of which a stepped profile of the connection of the material layers (10, 20) is obtained in cross-section.

Description

description

Method and device for joining two layers of material by means of high frequency welding

The invention relates to a method and a device for joining two layers of material by means of high-frequency welding.

In the known method of high-frequency welding two, consisting of a thermoplastic material Mate ^¬ riallagen are firmly bonded. For this purpose, the two layers of material are introduced into a joining device which comprises two welding electrodes which extend in the direction of a common axis and whose end faces are spaced apart from one another. The two Materi ^¬ Allagen come into the area where the joining connection is to be established between the two welding electrodes to lie. To take tolerances into account, the two layers of material protrude a short distance (protrusion) beyond the welding electrodes. For the production of the welded connection takes place

Pressing the material layers by moving one of the two welding electrodes in the direction of the other. By applying a high frequency to the welding electrodes, a molecular excitation takes place between the welding electrodes in the material of the material layers, so that this liquefies. After solidification of the material, the two layers of material are bonded to one another in a material-locking manner.

By standing over the welding electrodes protrusion results in a so-called weld overlay, which has a thickness which corresponds at least to the thickness of the superposed material layers. A further disadvantage consists in the fact that in the region of the weld seam protrusion a welding expulsion arises whose contour marking can be disturbing depending on the application of the article produced. The reason for this is that over the effective range of the joining device beyond the edge regions (ie, the supernatant) widened and set up by the joining process. This the sweat supernatant generating edge regions are necessary to ensure that between the electrically active end faces of the two welding electrodes, the material layers are present as a dielectric to avoid an electrical short circuit. The establishment of the material layers is attempted to counter this by providing suitable hold-down means. Of the

Welding shoots produced by the liquefaction of the material of the material layers and ensures a required Nahtfes ^¬ ACTION. The welding discharge is responsible for setting up the material layers on the outside of the joint.

In another high-frequency welding process, the material layers end with the contour of the two welding electrodes. In this method, there is the problem that due to insertion and cutting tolerances of the material layers can not be ensured that the faces of the welding electrodes are completely covered by the welding material. This has the consequence that between the electrical potentials an electrical short circuit can occur, which can affect the performance of welded joints.

It is an object of the present invention to provide a method and an apparatus which allow reliable process control and thereby a lower welding supernatant made ^¬ union.

This object is achieved by a method according to the features of claim 1 and a joining device according to the features of claim 7. Advantageous embodiments will be apparent from the dependent claims.

The invention provides a method for joining two layers of material by means of high-frequency welding. In this method, the two material layers are superimposed to form a material arrangement such that their front ends have a predetermined lateral spacing from one another. The material arrangement is inserted into a joining device in this way. causes the two layers of material to come to rest in the region of the front ends between a first welding electrode and a second welding electrode of the joining device. The front end of the first material layer comes to rest between respective opposite end faces of the first and second welding electrodes. The front end of the second material layer comes to rest outside the respective opposite end faces of the first and second welding electrodes. Subsequently, a joining process is carried out, whereby a stepped course of the connection of the material layers is obtained in cross section.

By means of this method, the thickness of the weld projection can be reduced to a maximum of one material layer thickness. Due to the different foil dimensions it comes in the area of

Welding supernatant to no perspiration. As a result, on the one hand, the geometry of the joint connection is improved, on the other hand, the desired reduction of the thickness of the joint connection can be realized.

According to an expedient embodiment of the method, the end face of the first material layer is arranged centrally, in particular centrally, relative to the end face of the adjacent, first welding electrode. In particular, the front end of the first material layer is based on the

End face of the remote, second welding electrode within the limits of the end face, ie, the end face of the second facing ^¬ Scheißelektrode. Hereby is sicherge ^¬ assumed that in the first layer of material no sweat supernatant which does not participate in the joining connection, occurs.

As a result, the setting up of the first material layer can be avoided. This favors the reduction of the thickness in the region of the joint connection. According to a further expedient embodiment, an outer edge section, the so-called weld projection, of the second material layer does not come into contact with the welding electrodes during the joining process. This means the outer edge cut does not participate in the joining connection. However, this geometrical design ensures that there is always enough material between the end faces of the two welding electrodes so that no electrical short circuit can occur between the electrical potentials of the two welding electrodes. This reduces service life of the joining device and results in more reliable welded joints.

According to a further expedient embodiment are as material layers plastic layers, in particular of a

thermoplastic, used. For example, thermoplastic polyurethane (TPU), PVC or polyamide can be used. Basically, such materials are suitable for producing a joint connection, which can be liquefied and pressed by means of high frequency.

It is also expedient if, in the context of the method according to the invention, the outer edge section of the second material layer rests on an insert frame. The insert frame is preferably made of a non-conductive material, such as a plastic. As a result, at least one of the two welding electrodes can adjoin the insert frame directly without being electrically active with respect to the other welding electrode. In particular, an erection, i. a mechanical deformation of the second material layer to be prevented during the welding process or the joining operation.

A support surface of the insert frame, and the layer adjacent to the second material layer end face of the second Schweißelek ^¬ trode can be arranged to each other such that they lie in a common plane. This can reliably ensured that the second material layer does not deform undesirably during the joining process, in particular establishes, thereby causing an increase in the feet ^¬ geverbindung adversely. The object is further achieved by a joining device for joining two layers of material by means of high frequency welding, which comprises a first welding electrode and a second welding electrode, which extend in the direction of a common axis, wherein the first welding electrode comprises a first end face and the second welding electrode has a second end face, which are spaced apart from each other. According to the invention, the area of the first end face is greater than the area of the second end face.

The different surface of the welding electrodes in conjunction with different dimensions or the different arrangement of the front ends of the two layers of material with regard to their lateral end position ensure that no sweat exudation arises in the region of the supernatant. This is ensured in particular by the fact that the

Welding electrode with the smaller width is relevant for the above connection. According to an expedient embodiment, an insert frame is arranged adjacent to the second welding electrode with a support ^¬ surface for a material layer, wherein the support surface and the end face of the second welding electrode are arranged to ^¬ each other that they lie in a common plane. The insert frame is made of a non-conductive material to allow abutment of the second welding electrode without becoming electrically active.

According to a further expedient embodiment, the first electrode is transverse to a weld seam to be joined by two Mate ^¬ riallagen wider than the second welding electrode.

In accordance with a further embodiment, a section of the end face of the first electrode faces the contact surface of the insert frame.

It is also expedient that, in a lateral view of the joining device, facing away from the insert frame Side edges of the first and the second welding electrode are arranged in a plane which is parallel to the common axis. This ensures that the material inward joint connection is symmetrical, resulting in an improved joint connection.

Incidentally, the same advantages as those described above in connection with the method according to the invention are achieved.

The invention can be used in particular for producing fillable, elastic cushions for shaping seat contours. Such cushions allow individual adaptation of the seats to an occupant of a vehicle. In addition to the durability, noise requirements are also placed on the air cushions, which means that no creaking noises are to be expected in the entire seat from the cushions during a seat adjustment function. Furthermore, the contour of the cushion must under no circumstances be visible on the outside of the seat. As for the required requirements in particular the design of the

Weld supernatant of the cushion is relevant, the described method is particularly suitable for this purpose, since a small and in particular thin weld overlap can be achieved. The invention will be explained in more detail below with reference to embodiments ^¬ examples in the drawing. Show it:

Fig. 1 is a schematic cross-sectional view of a known from the prior art joining device;

FIG. 2 shows a schematic cross-sectional view of a part through a bladder produced with the joining device according to FIG. 1; FIG. Fig. 3 is a schematic cross-sectional view of a

alternative, known procedure for producing a bladder with shortened weld supernatant; 4 shows a schematic cross-sectional view of a joining device according to the invention; and

FIG. 5 is a schematic cross-sectional view of a portion of a bladder with improved weld supernatant produced by a device as shown in FIG. 4.

1 shows a conventionally formed joining device 1 for joining two material layers 10, 20 using a high-frequency welding method. The joining device 1 comprises a first, upper welding electrode 41 and a second, lower welding electrode 42. A first end face of the first

Welding electrode 41 is identified by the reference numeral 43. The second welding electrode 42 has a second end face 44. The first and second end faces 43, 44 are spaced apart and parallel to each other against ^¬ oppositely disposed. The first and the second end face are arranged on ^¬ such that the end faces 43, 44 no lateral offset (that is no offset in the plane of the drawing from left to right) have.

In between the welding electrodes 41, 42 and their

End surfaces 43, 44 formed distance are two superimposed layers of material 10, 20 of a thermoplastic

Plastic arranged. End-side ends 11, 21 of the two material layers 10, 20 lie directly above one another, ie have no lateral offset to one another. Adjacent to the second welding electrode 42, a Einle ^¬ frame 50 is disposed of a plastic. The insert frame 50 has a support surface 51 and a contact surface 52. The front ends 11, 21 of the two layers of material 10, 20 both adjoin the boundary surface 52 of the insert frame.

The second end face 44 of the second welding electrode 42 is arranged elevated relative to the support surface 51 by a predetermined distance. A recess 47 of the first welding electrode ₀

O

41, which faces the insertion frame 50, is formed in its height such that it corresponds to the height offset of the second end face 44 and bearing surface 51. Due to the provided at the first, upper welding electrode 41

Return 47 and the same width of the end faces 43, 44 it follows that the first welding electrode 41 has a greater width 45 compared to a width 46 of the second, lower welding electrode 42. To produce the joint connection or welded connection between the material layers 10, 20, the first welding electrode 41 is then moved along the common axis in the direction of the second welding electrode 42 in order to press the material layers. Subsequently, the two welding electrodes 41, 42 are acted upon with a predetermined frequency, for example 27 MHz, whereby a molecular excitation of the material of the two material layers 10, 20 takes place in the region of the end faces 43, 44, whereby a cohesive connection or joining seam ensues between them after cooling the material layers 10, 20 is achieved.

As can be readily seen from the cross-sectional illustration of FIG. 1, the first and the second material layers 10, 20 protrude beyond the edges of the insert frame 50 facing the insert frame 50

End faces 43, 44 also. These edge portions are identified by the reference numerals 12, 22. By compressing the two layers of material 10, 20 and the simultaneous liquefaction of the material of the material layers 10, 20, the material layers 10, 20 in the region of their wall sections 12, 22 up or down. Due to the recess 47 or the bearing surface 51 of the insert frame 50, this setting up or deformation can be limited with respect to its path.

The erected edge portions 12, 22 are well visible from Fig. 2. The reference numeral 5 indicates the joining seam 5 achieved by the high-frequency welding, which extends into the plane of the sheet. Between the first Ma ^¬ teriallage 10 and the second material layer 20 extends in the embodiment of a bubble inside 8, provided that the two Material layers 10, 20 are provided for forming a bubble or a cushion.

Reference numerals 6 and 7 denote a respective welding projection along the joining seam 5 (which extends into the plane of the sheet), which is required for a required seam strength. While the welding expulsion 6, which is directed towards the inside of the bladder 8, is not troublesome, the welding expulsion 7 ensures the unwanted and irreversible erection of the non-welded wall sections 12, 22. While the thickness of the joining seam 5 is approximately the thickness of one of the layers of material 10, 20, a minimum thickness of twice the thickness of a material layer results in the region of the weld projection (assuming the material layers 10, 20 have the same thickness).

FIG. 3 shows an alternative, known welding concept for high-frequency welding, with which the thickness of the weld projection can be reduced. In this case, the front ends 11, 21 of the material layers 10, 20 to be joined end with the contour of the welding electrodes 41, 42. However, due to insertion and cutting tolerances of the welding material, it is not ensured that the end faces 43, 44 of the

Welding electrodes 41, 42 are completely covered by the material of the material layers 10, 20. This can disadvantageously have the consequence that an electrical short circuit arises between the electrical potentials, whereby the production can be disturbed. Fig. 5 shows the proposed welding concept according to the invention. As in the arrangement in Fig. 1, the second borders

Welding electrode 42, an insert frame 50 made of plastic. This has the already described bearing surface 51 and the Be ^¬ boundary surface 52. The support surface 51 and the

End face 44 of the second welding electrode 42 lie in one plane. The second material layer 20 adjoins the boundary surface 52 of the insert frame 50 with its front end 21. This means that the front end 21 comes outside the lying opposite faces 43, 44 of the first and second welding electrode 41, 42 to lie.

In contrast, the front end 11 of the first material layer 10 comes to rest between the opposite end faces 43, 44 of the first and second welding electrodes 41, 42. In particular is the end face 11 of the first Mate ^¬ riallage, based on the end face 44 of the second

Welding electrode, within the limits of their end face 44. In the illustration shown in Fig. 4, the end-side end 11 is an example in alignment with the adjoining the insert frame 50 side edge of the second welding electrode 42nd

As can readily be seen from the illustration of FIG. 4, the first welding electrode 41 faces the second one

Welding electrode 42 has a greater width 45, that is, the width 45 is greater than the width 46. More specifically, the first end face 43 has the greater width than the second end face 44. In this case, the edges or side surfaces of the first and second electrodes 41, 42 facing away from the insertion frame 50 come to lie in alignment with one another. Thus, the edges or side surfaces lie in a common plane which extends parallel to the common axis of the first and second welding electrodes 41, 42.

Reference numeral 30 denotes a lateral offset of the front ends 11, 21 of the first and second layers of material 10, 20. The length of the lateral distance corresponds to the length of the weld projection, i. the material region of the second material layer 20 which does not participate in the cohesive connection of the material of the first and second material layers 10, 20. It is understood that despite the different widths 45, 46 of the first and the second welding electrode 41, 42 and first and second end faces 43, 44, the width of the joint seam 5 through the surface of the second

End face 44 of the second welding electrode 42 is determined. The described arrangement and procedure has the consequence that, on the one hand, it is always ensured that no electrical short circuit can occur between the first and the second welding electrodes 41, 42, since the lower or second material layer 20 generally protrudes laterally beyond the two welding electrodes 41, 42 , Due to the fact that the second material ^layer 20 rests on the support surface 51 of the insert frame 50 at the same time, this can not unfold unfavorably, as is the case with the arrangement according to FIG. The positioning is equally prevented in the first material layer 10 that there no edge portion protrudes beyond the first welding electrode 41 also.

As a result, as shown in Fig. 5, there is a stepped course of the connection of the material layers 10, 20. The reference numeral 5 in turn the joint seam is characterized. The reference numeral 22 denotes the edge portion of the second material layer 20, which projects beyond the end face 44 of the second welding electrode 42. The length of this edge portion 22 corresponds to the lateral distance 30 between the front ends 11, 21 of the two material layers 10, 20th

As can also be seen from FIG. 5, outside of the inside of the bladder 8 there is also no sweat release. Such a welding expulsion 6 is directed only to the inside of the bubble 8 out. The residual thickness of the outwardly directed edge region corresponds to the thickness of the second material layer 20. The outwardly directed weld projection (reference symbol 7 in FIG. 1) can be avoided in the proposed method, since this is crushed by the pressure of the welding electrodes 41, 42. Reference sign list

I bubble

5 jointing

6 perspiration

7 perspiration

8 inside of the bladder

10 first material situation

II frontal end of the material layer

12 edge portion of the first material layer 10

20 second material layer

21 frontal end of the material layer

22 edge portion of the second material layer 20

30 lateral distance between the front ends 11, 21 40 electrode assembly

41 first welding electrode

42 second welding electrode

43 end face of the first welding electrode

44 end face of the second welding electrode

45 width of the first welding electrode

46 width of the second welding electrode

47 return

50 insert frame

51 bearing surface

52 boundary surface

Claims

claims

1. A method for joining two layers of material (10, 20) by means of

High-frequency welding, in which

- The two layers of material (10, 20) are superposed in such a way to a material ^¬ arrangement that their front ends (11, 21) have a predetermined lateral distance (30) to each other;

the material arrangement is introduced into a joining device (40) such that the two material layers (10, 20) in the

Area of the front ends (11, 21) between a first welding electrode (41) and a second welding electrode (42) of the joining device (40) come to rest, wherein the front end (11) of the first material layer (10) between respective, opposite end faces (43, 44) of the first and second welding electrodes (41, 42) comes to rest and the front end (21) of the second material layer (20) outside the respective opposite end faces (43, 44) of the first and second welding electrode (41, 42) comes to rest;

the joining process is carried out, whereby a stepped course of the connection of the material layers (10, 20) is obtained in cross section.

2. The method of claim 1, wherein the front end (11) of the first material layer (10) relative to the end face (43) of the adjacent, first welding electrode (41) centrally, in particular ^¬ centered, is arranged.

3. The method of claim 1 or 2, wherein the front end (11) of the first material layer (10) relative to the end face (44) of the remote, second welding electrode (42) within the limits of the end face (44).

4. The method according to any one of the preceding claims, wherein an outer edge portion (22) of the second material layer (20) during the joining operation is not in contact with the welding electrodes (41, 42).

5. The method according to any one of the preceding claims, wherein as material layers (10, 20) plastic layers, in particular of a thermoplastic material, are used.

6. The method according to any one of the preceding claims, wherein the outer edge portion (22) of the second material layer (20) rests on an insert frame (50).

7. The method of claim 5, wherein a bearing surface (51) of the insert frame (50) and the second material layer (20) adjacent end face (44) of the second welding electrode (42) are arranged to each other such that they in a ge ^¬ common level lie.

8. joining device (40) for joining two layers of material (10, 20) by means of high frequency welding, comprising a first

Welding electrode (41) and a second welding electrode (42) extending in the direction of a common axis, wherein the first welding electrode (41) has a first end face (43) and the second welding electrode (42) has a second end face (44) spaced apart from each other, characterized in that

the area of the first end face (43) is greater than the area of the second end face (44).

9. joining device according to claim 7, characterized in that adjacent to the second welding electrode (42) an insert frame (50) having a support surface (51) for a material layer (20) is arranged, wherein the support surface (51) and the end face (44 ) of the second welding electrode (42) are arranged to each other such that they lie in a common plane.

10. Joining device according to claim 7 or 8, characterized in that the first electrode (41) transverse to a joining seam of two material layers to be joined (10, 20) is wider than the second welding electrode (42).

11. Joining device according to one of claims 7 to 9, characterized in that a portion of the end face (43) of the first electrode (41) of the support surface (51) of the insert frame (50) opposite.

12. Joining device according to one of claims 7 to 10, characterized in that, in a lateral view of the joining ^¬ device, the side facing away from the insert frame (50) side edges of the first and the second welding electrode (41, 42) are arranged in a plane which is parallel to the ge ^¬ common axis.