METHOD FOR PRODUCING A MOULDED PART ASSEMBLY AND CORRESPONDING PRODUCTION DEVICE

Abstract

The application relates to a method for producing a moulded part assembly from a first plastic moulded part and a second plastic moulded part by means of laser welding, wherein the first plastic moulded part consists at least partially of a first material and the second plastic moulded part consists at least partially of a second material that can be welded to the first material, wherein a welding region of the second plastic moulded part is arranged in a stepped receiving means of the first plastic moulded part, or vice versa. According to the invention, during the laser welding, the first plastic moulded part and the second plastic moulded part are to be shifted onto one another in a shifting direction. The invention also relates to a production device for producing a moulded part assembly.

Claims

1. A method for producing a molded part assembly from a first plastic molded part and from a second plastic molded part by laser welding, wherein the first plastic molded part consists at least partially of a first material and the second plastic molded part consists at least partially of a second material which can be welded to the first material, wherein a welding region of the second plastic molded part is arranged in a stepped receiving means of the first plastic molded part or vice versa, wherein the plastic molded parts are present as a fluid line element, that a first welding surface of the first plastic molded part which welding surface is located at least with a partial surface in the first rotational surface and faces the second plastic molded part is formed in the receiving means, and a front-side, second welding surface located in the second rotational surface and facing the first plastic molded part is formed on the second plastic molded part, and that the first plastic molded part and the second plastic molded part are shifted onto one another in the shifting direction during the laser welding, wherein the first welding surface and the second welding surface contact one another or are supported on one another by an insertion part, and wherein a laser beam used for the laser welding is directed inward or outward in a radial direction.

2. The method according to claim 1, wherein the first welding surface and the second welding surface are constructed in such a manner that the first rotational surface and the second rotational surfaceviewed in a longitudinal sectionare angled parallel to one another or against and/or that the first rotational surface and/or the second rotational surface stand vertically on the shifting direction.

3. The method according to claim 1, wherein the first welding surface is constructed with at least one other partial surface which is angled opposite the partial surface.

4. The method according to claim 1, wherein the first welding surface is adjacent to an inner circumferential surface of the first plastic molded part and that the second welded surface is adjacent to an outer circumferential surface of the second plastic molded part, wherein the inner circumferential surface and the outer circumferential surfaceviewed at least in sections in the circumferential directionare arranged relative to one another with a clearance fit or a transitional fit.

5. The method according to claim 1, wherein a laser beam used for the laser welding receives the first rotational surface in itself and is arranged in particular centrally or adjacently, in particular directly adjacently to the first rotational surface.

6. The method according to claim 5, wherein the laser beam is positioned in a stationary manner relative to the first plastic molded part and/or to the second plastic molded part.

7. The method according to one of the previous claims claim 1, wherein the laser beam is aligned parallel to the first rotational surface or is angled relative to the first rotational surface, wherein the first welding surface lies at least partially, in particular entirely in the laser beam.

8. The method according to claim 1, wherein the second plastic molded part is constructed with several layers, wherein the layers of the second plastic molded part consist of materials with different melting temperatures and the second welding surface is formed by at least one of the layers, in particular only by a subset of the layers.

9. The method according to claim 1, wherein the first plastic molded part and/or the second plastic molded part and/or the insertion part are produced from a laser-transparent material or from a laser-absorbing material.

10. The method according to claim 1, wherein the relative position of the first plastic molded part and of the second plastic molded part to one another is determined over time, in particular and at least one point in time and is evaluated for ensuring the quality of the molded part assembly.

Description

[0058] FIG. 1 shows a schematic view of a molded part assembly 1 in a longitudinal section relative to a longitudinal central axis 2. The molded part assembly 1 comprises a first plastic molded part 3 and a second plastic molded part 4. Both plastic molded parts 3 and 4 can be designed, for example, as fluid line elements. They are only shown here by way of example and in a schematic manner. The first plastic molded part 3 is preferably a fluid coupling and the second plastic molded part 4 is a fluid line. The plastic molded parts 3 and 4 can basically be produced in any manner, for example, by injection molding or extruding. The first plastic molded part 3 is preferably an injection-molded part and the second plastic molded part 4 an extrusion molded part. However, even other embodiments are possible.

[0059] The first plastic molded part 3 comprises a receiving means 5 for the second plastic molded part 4 and for a welding region 6 of the second plastic molded part 4. The receiving means 5 comprises a mouth opening 7 formed on the front side on the first plastic molded part 3 and is limited on the side opposite the mouth opening 7viewed in the axial directionby a step 8. The receiving means 5 is designed to this extent as a stepped receiving means. The step 8 brings about a change in the dimensions and of the inner cross-sectional surface of the receiving means 5. In addition, in the exemplary embodiment shown here it preferably forms an end stop for the second plastic molded part 4. The plastic molded parts 3 and 4 are correspondingly designed so that the second plastic molded part 4 can be introduced into the receiving means 5 up to the attaining of the step 8 and subsequently rests on the latter or is supported on it.

[0060] A first welding surface 9 is formed in the receiving means and rests in the rotational surface at least by a partial surface 10. The first welding surface 9 or the partial surface 10 faces the second plastic molded part 4. The first welding surface 9, in particular the partial surface 10, is preferably formed by the step 8. The first welding surface 9 and its partial surface 10 is preferably annular, in particular with a circular ring shape. A second welding surface 11 is formed on the second plastic molded part 4 on the front side. This welding surface is located in the second rotational surface and faces the first plastic molded part 3. The second welding surface 11 rests on the first welding surface 9, in particular on the partial surface 10 of the first welding surface 9. In the exemplary embodiment shown here, the front side of the second plastic molded part 4 is greater in a radial direction than the step 8 so that the second plastic molded part 4, viewed in a cross section, projects inward over the step 8.

[0061] An inner circumferential surface 12 of the first plastic molded part 3 follows the first welding surface 9 and which limits the receiving means 5 in an outward radial direction. The inner circumferential surface 12 extends in an axial direction preferably from the first welding surface 9 to the mouth opening 7 through which the second plastic molded part 4 can be introduced into the receiving means 5. The inner circumferential surface 12 is preferably cylindrical, especially circularly cylindrical. For example, it encloses a certain angle, in particular 90, with the first welding surface 9 and the partial surface 10. On the other hand, the second welding surface 11 borders on an outer circumferential surface 13 of the second plastic molded part 4. The outer circumferential surface 13 can also be cylindrical, especially circularly cylindrical, and encloses an angle, in particular an angle of 90 with the second welding surface 11, preferablyviewed in the circumferential direction, at least in areas or continuously.

[0062] The plastic molded parts 3 and 4 are constructed in such a manner that the inner circumferential surface 12 and the outer circumferential surface 13 are in any case not or at bestviewed in the circumferential directionarranged in areas with a press fit to one another but rather only with a clearance fit or a transitional fit. This is indicated in the representation by the distance between them. It is preferably provided that the outer circumferential surface 13 is also formed by ribs which are not shown here and which are formed at a distance from each other in a circumferential direction on the plastic molded part 4 and project in a radial direction in the direction of the plastic molded part 3 and the inner circumferential surface 12. For example, the outer circumferential surface 13viewed in the circumferential directionrests only in the area of the ribs on the inner circumferential direction 12 and in areas located between the ribs with a lesser surface pressure or none at all. In the latter case the outer circumferential surface is arranged in the areas between the ribs, therefore at a distance from the inner circumferential surface. The ribs have their longitudinal central axis in an axial direction, therefore preferably parallel to the longitudinal central axis 2. They serve for a simple and reliable centering of the plastic molded part 4 as regards the plastic molded part 3 and can accordingly also be designated as centering ribs.

[0063] In the first embodiment shown here the first rotational surface and the second rotational surface are arranged parallel to one another and both stand vertically on the longitudinal central axis 2 and the shifting direction of the plastic molded part 3 and 4 indicated by the arrows 14 and 15 in which they are shifted onto one another during a laser welding process. The shifting direction is preferably parallel to the longitudinal central axis 2 or coincides with it. The two rotational surfaces are located in the embodiment shown here in the same plane or at least in two planes arranged parallel to one another.

[0064] In order to produce the molded part assembly 1, the plastic molded parts 3 and 4 are connected to one another by laser welding. For this, the welding region 6 of the second plastic molded part 4 is arranged in the receiving means 5 of the first plastic molded part 3. A laser beam 16 is generated already before the welding surfaces 9 and 11 make contact with one another or after such a contacting, with which the laser welding is performed. The first plastic molded part consists at least partially of a first material which is laser-transparent whereas the second plastic molded part 4 consists at least partially of a second material which is laser-absorbing. In addition, the second material can be welded to the first material and can, therefore, be firmly bonded to it by the laser welding. The first material and the second material can basically be different or consist of the same base material which is made laser-transparent and/or laser-absorbent by additives.

[0065] During the laser welding the two plastic molded parts 3 and 4 are shifted onto one another with welding surfaces 9 and 11 located on one another. This is made possible by the melting of the first plastic molded part 3 and/or of the second plastic molded part 4 in areas by the laser beam 16. For shifting the plastic molded parts 3 and 4 onto one another, a shifting force is impressed on them. For example, the shifting force is impressed in the direction of the arrow 14 onto the second plastic molded part 4 and/or in the direction of the arrow 15 on the first plastic molded part 3.

[0066] FIG. 2 shows a schematic view of a second embodiment of the molded part assembly 1. It is basically similar to the first embodiment, so that in the following only the differences will be discussed and otherwise reference is made to the previous explanations. The differences are that the front surface of the second plastic molded part 4 is smaller in the radial direction than the step 8, so that, viewed in cross sectionthe front surface of the second plastic molded part 4 rests completely on the step 8 during the laser welding.

[0067] FIG. 3 shows a third embodiment of the molded part assembly 1. Again, only the differences from the first embodiment will be discussed and otherwise reference is made to the previous explanations. The differences are that the first rotational surface, which defines the first welding surface 9, is bent relative to the second rotational surface defining the second welding surface 11. In addition, the first rotational surface is obliquely aligned relative to the longitudinal central axis 2 and to the shifting direction and therefore intersects them at an angle different from 90. The first welding surface 9 is present in the exemplary embodiment shown here as a sectional surface of a cone envelope. In contrast thereto, the first rotational surface is preferably aligned vertically to the longitudinal central axis 2. However, it can also be arranged obliquely to the latter, but is preferably bent relative to the first rotational surface, in particular inclinedviewed in longitudinal sectionin the other direction.

[0068] FIG. 4 shows a fourth embodiment of the molded part assembly 1. The differences from the first embodiment, the description of which is basically referred to, are that the first welding surface 9 comprises in addition to the partial surface 10 another partial surface 17. This latter one is bent relative to the partial surface 10 and preferably directly follows it. The partial surface 17 is also plane or level just as the partial surface 10. The welding surface 9 is located in the exemplary embodiment shown vertically to the longitudinal central axis 2 whereas the partial surface 17 is bent and to this extent is shaped like a sectional surface of a cone envelope.

[0069] FIG. 5 shows a variant of the molded part assembly 1 in which the second plastic molded part 4 is multi-layered and to this extent has multiple layers, here, for example, layers 18, 19 and 20. Otherwise, reference is made to the previous explanations. In particular, the welded surfaces 9 and 11 can be shaped according to one of the embodiments according to the previous explanations. For example, the layers 18, 19 and 20 consist of different materials. In particular, it is provided here that the layer 18 arranged directly adjacent to the inner circumferential surface 12 limiting the receiving means 5 in an outwardly radial direction consists of a material that can be welded to the material of the first plastic molded part 3. In contrast thereto, the layer 19 be constructed as a filler layer and to this extent can consist of a material, in particular an economical material, that cannot be welded to the first material of the first plastic molded part 3. On the other hand, the layer 20 can be constructed in such a manner that it has a sufficient resistance to a fluid to be transported in the second plastic molded part 4. For example, the layer 18 as well as the first plastic molded part 3 consist of PA6.12 or PA12. The layer 19 can consist of PA6, in contrast to which the layer 20 is produced, for example, from PPA or fluoropolymer.

[0070] It can be additionally or alternatively provided that the first plastic molded part 3 and the layer 18 consist of a laser-absorbing material whereas a laser-transparent material is provided for the layers 19 and 20. In this instance, for example, an inner welding can be performed in which the laser beam 16 passes outwardly through the layers 19 and 20 in a radial direction and is absorbed by the layer 18 and the first plastic molded part 3 so that the layer 18 is welded to the first plastic molded part 3. In this instance the layer 18 consists of the second material of the second plastic molded part 4, which can be welded to the first material of the first plastic molded part 3. However, any other material combinations can also be realized for the layers 18, 19 and 20.

[0071] FIG. 6 shows a schematic view of the molded part assembly 1, wherein an inserted part 21 is arranged between the first plastic molded part 3 and the second plastic molded part 4. The inserted part 21 preferably lies, viewed in an axial direction, on the one hand on the first plastic molded part 3, in particular on the first welding surface 9, and on the other hand on the second plastic molded part 4, in particular on the second welding surface 11. In the radial direction it can rest on the inner circumferential surface 12 or be arranged at a distance from it. The insertion part 21 preferably consists of laser-absorbing material. The first plastic molded part 3 and the second plastic molded part 4 can both consist of laser-transparent material. However, one of the plastic molded parts 3 and 4 can also consist of a laser-absorbing material, for example, the first plastic molded part in an inner welding and the second plastic molded part in an outer welding. The insertion part 21 is melted under the influence of the laser beam 16 so that it is made possible to shift the plastic molded parts 3 and 4 onto one another.

[0072] FIG. 7 shows a diagram in which a relative position s of the two plastic molded parts 3 and 4 is recorded over the time t. After a time tt.sub.0, the laser welding is carried out and the laser beam 16 is therefore generated. Likewise, after the time tt.sub.0, the shifting of the plastic molded part 3 and 4 onto one another and/or their loading with the shifting force begins. The laser beam 16 stays actuated for a total welding time which ends at time t=t.sub.1. The welding time is therefore t.sub.1tt.sub.1. A holding time for t.sub.1tt.sub.2 directly follows the welding time. The holding time ends at the time t=t.sub.2.

[0073] During the time consisting of the welding time and the holding time the relative position s is retained for the time t. The relative positions S=S.sub.0, S.sub.1 and S.sub.2 are indicated purely as examples here for the times t=t.sub.0, t.sub.1 and t.sub.2. However, only one relative position at a certain time or a course of the relative position s can also be detected. Such a relative position course is indicated by the course 22 which runs through the previously explained relative positions. If this course 22 follows a theoretical value course or lies in a theoretical value range 23, it can be assumed that the produced molded part assembly 1 is in order. Otherwise, a produced molded part assembly 1 which is not in order as assumed.

[0074] An economical laser welding of the two plastic molded parts 3 and 4 with a reliable process is possible with the aid of the previously described molded part assembly 1 and the explained procedure. The production of the molded part assemblies 1 is on the one hand possible with low waste and on the other hand the waste can be reliably recognized.