METHOD OF HEATING SEMI-FINISHED PRODUCTS

Abstract

A method involves heating fiber-reinforced semi-finished products of differing wall thickness to a required temperature above the glass transition range or the matrix melting temperature of a plastic matrix of the semi-finished product to be heated. In a first step, the semi-finished product to be heated is heated by thermal conduction to below the glass transition range or the matrix melting temperature. In a further step, the remaining amount of heat for reaching the required temperature above the glass transition range or the matrix melting temperature is introduced by thermal radiation or thermal convection.

Claims

1. A method of heating fiber-reinforced semi-finished products of differing wall thickness to a required temperature above the glass transition range or the matrix melting temperature of a plastic matrix of the semi-finished product to be heated, wherein, in a first step the semi-finished product to be heated is heated by means of thermal conduction to below the glass transition range or the matrix melting temperature and in a further step the remaining amount of heat for reaching the required temperature above the glass transition range or the matrix melting temperature is introduced by means of thermal radiation or thermal convection.

2. The method as set forth in claim 1, wherein in the first step the semi-finished product to be heated is heated by means of thermal conduction to a temperature of up to 50 C. below the glass transition range or the matrix melting temperature, particularly preferably to a temperature which is up to 30 C. below the glass transition range or the matrix melting temperature.

3. The method as set forth in claim 1, wherein in the first step pressure is applied to the semi-finished product to be heated.

4. The method as set forth in claim 1, wherein in the first step the heating operation is carried out for a time which depends on the required time for heating through the thickest region of the semi-finished product to be heated.

5. The method as set forth in claim 1, wherein in the further step after reaching the required temperature that is maintained for an adjustable time for uniform heating of the semi-finished product.

6. An apparatus for heating fiber-reinforced semi-finished products of differing wall thicknesses wherein the apparatus has a flexible thermal conduction layer which can be adapted to differences in wall thickness of the semi-finished product to be heated and by which heat energy can be transmitted by thermal conduction to the semi-finished product to be heated.

7. The apparatus as set forth in claim 6, wherein there are provided a firstpreferably upperand a secondpreferably lowertool half, between which the semi-finished product to be heated can be arranged.

8. The apparatus as set forth in claim 1, wherein the first and second tool halves each have a heatable base plate respectively and at least one and preferably both tool halves has a flexible thermal conduction layer.

9. The apparatus as set forth in claim 1, further comprising a pressing device for pressing the flexible thermal conduction layer against the semi-finished product to be heated so that the flexible thermal conduction layer bears against the surface of the semi-finished product to be heated, that has differences in wall thickness.

10. The apparatus as set forth in claim 7, wherein the pressing device includes the first and a second tool half which are movable relative to each other for the pressing effect.

11. The apparatus as set forth in claim 1, wherein the flexible thermal conduction layer is in the form of a vacuum mat and after the operation of applying the flexible thermal conduction layer to the surface of the semi-finished product to be heated, that has the differences in thickness, has been effected, it can be fixed in its shape by applying a vacuum.

12. The apparatus as set forth in claim 1, wherein the flexible thermal conduction layer comprises an elastomer, particularly preferably a silicone, wherein it is preferably provided that the flexible thermal conduction layer has fillers for increasing thermal conductivity.

13. A heating apparatus comprising a first heating station in the form of the apparatus as set forth in claim 1, and a second heating station in which the semi-finished product which was pre-heated in the first heating station can be heated by means of thermal radiation or thermal convection.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG. 1 is a schematic view of a heating apparatus according to the invention;

[0030] FIG. 2a is a schematic view of a first heating station according to the invention; and

[0031] FIG. 2b is another schematic view of the first heating station.

DETAILED DESCRIPTION OF THE INVENTION

[0032] A heating apparatus according to the invention is shown in FIGS. 1, 2a and 2b.

[0033] The heating apparatus 7 has a first heating station 8 and a second heating station 9. The second heating station 9 serves for introducing heat by means of thermal radiation or thermal convection. It has two plates 10, between which the semi-finished product 1 can be placed after pre-heating in the first heating station, and does not have to be described in greater detail as it corresponds to the state of the art. The plates 10 can have known heating elements.

[0034] The first heating station 8 is shown in FIG. 2a in an opened position and in FIG. 2b in a closed position. The first heating station 8 has a first (upper) tool half 3 and a second (lower) tool half 4. They each comprise a heatable base plate 5, 6 respectively and a flexible thermal conduction layer 2 arranged thereon. The devices required for heating the base plates 5, 6 are not shown as they correspond to the state of the art.

[0035] By comparison between FIGS. 2a and 2b it is possible to see how the flexible thermal conduction layer 2 adapts to differences in wall thickness of the semi-finished product 1 to be heated. Instead of providing a flexible thermal conduction layer 2 on both tool halves 3, 4 as here, the provision of only one flexible thermal conduction layer 2 on one of the two tool halves 3, 4 could also be sufficient. The flexible thermal conduction layer or layers 2 would not necessarily have to be in one piece, other than as illustrated.

LIST OF REFERENCES

[0036] 1 semi-finished product

[0037] 2 flexible thermal conduction layer

[0038] 3 first tool half

[0039] 4 second tool half

[0040] 5 base plate of the first tool half

[0041] 6 base plate of the second tool half

[0042] 7 heating apparatus

[0043] 8 first heating station

[0044] 9 second heating station

[0045] 10 plates of the two heating stations