WO2011006656A1

WO2011006656A1 - Method for producing plastic molded parts

Info

Publication number: WO2011006656A1
Application number: PCT/EP2010/004309
Authority: WO
Inventors: Richard Fischer; Franz Golling; Siegfried Guertner; Michael Ippisch; Wolfgang Ortlieb; Marcus Wolf
Original assignee: Premium Aerotec Gmbh
Priority date: 2009-07-16
Filing date: 2010-07-15
Publication date: 2011-01-20
Also published as: DE102009033702B4; DE102009033702A1

Abstract

The invention relates to a method for producing plastic molded parts, comprising the following steps: a) providing a board comprising plastic material; b) machining the board to produce a blank having a contour that corresponds to the flat projection of the finished molded part in the plane of the board; c) heating the blank; d) plastically deforming the heated blank into a molded part having the net shape using a molding tool, wherein at least one of the edges of the blank is seated against the support surfaces provided in the molding tool or is rests there during deformation.

Description

Process for the production of molded plastic parts

TECHNICAL AREA

The present invention relates to a process for the production of molded plastic parts and to a mold for carrying out this process. In particular, the invention relates to a process for the production of molded parts made of fiber-reinforced, for example carbon fiber reinforced, plastic.

STATE OF THE ART

So far, it has been common to moldings made of plastic, for example

Carbon fiber reinforced plastic, which are used, for example, in aircraft, initially under thermal action to deform and then work the molded part thus prepared to the required extent. This machining usually takes place on multi-axis, numerically controlled milling machines. A disadvantage of this approach is the high cost of the subsequent to the forming process machining of the molding.

In addition, the edges of the molding are roughened by the processing subsequent to the forming process, whereby the ends of the fibers contained in the plastic are exposed. In order to avoid damaging the fibers during the subsequent use of the molded article, for example by the action of gases or liquids on the open edges, it is necessary to seal the edges of the molded article after processing, thereby requiring a further processing step.

It is therefore an object of the present invention to provide a method for the production of plastic moldings in which the number of moldings

Process steps is reduced, and thus the production costs compared to the State of the art are lower. Also, a suitable for such a method mold is to be specified.

The object relating to the method is achieved by the method according to

Claim 1 solved.

This inventive method for the production of molded parts

Plastic has the following steps:

a) providing a plastic material having a board;

b) processing the blank to produce a blank with a contour corresponding to the development of the finished molded part in the plane of the board; c) heating the blank;

d) plastically forming the heated blank into a molded part with the final shape by means of a molding tool, wherein at least one of the edges of the blank is applied during deformation of provided in the mold bearing surfaces or comes to rest there.

ADVANTAGES In this process, the board is already worked to measure in step b) so that additional processing after the forming step is no longer required. The contour edges of the blank processed in step b) are sealed by the heating in step c) by the then flowable matrix material of the plastic, so that the additional step of sealing in the molded part edges required in the prior art can be dispensed with. The provision of contact surfaces in the mold to which at least one of the edges of the blank during deformation comes to rest or rests during the entire forming process, ensures that this edge is dimensionally stable at the end of the forming step and need not be further revised. Preferably, all relevant edges of the blank become during the step the plastic forming against corresponding contact surfaces on the mold, so-called "net-molding edges" brought to rest or lie during the forming of such contact surfaces of the mold, whereby the dimensional accuracy of the molding edges and consequently of the entire finished molded part is guaranteed.

In a preferred development of the method according to the invention, the plastic material is fiber-reinforced, in particular reinforced with carbon fibers, and the plastic material has a thermoplastic matrix material, in particular PPS (polyphenylene sulfide).

Preferably, the processing of the board in step b) by non-cutting and / or machining steps. The non-cutting

Processing steps can be, for example, cutting or punching and the machining steps are, for example, drilling, sawing or milling.

The heating of the blank in step c) is preferably carried out by

Heat conduction. As a result, a particularly homogeneous heating of the board is achieved.

It is particularly advantageous if the molded part formed in step d) remains in the closed mold for a predetermined period of time and if during this time the temperature of the mold and thus of the molded part is cooled down to a predetermined temperature before the finished molded part is removed from the mold becomes. This cooling of the molding in

Forming tool ensures a particularly good dimensional stability of the finished molding.

The directed to the mold part of the task is by the

Mold with the features of claim 6 solved. The molding tool has at least one die and at least one stamp, which are movable relative to one another, wherein the punch and / or the die has contact surfaces for at least one of the edges of the blank to be formed. These contact surfaces, which are also referred to as "net-molding edges", ensure a fixation of the associated edges of the blank to be formed, whereby a dimensional accuracy of the corresponding edges of the finished molded part is ensured.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described by way of example with reference to the drawings; it shows:

1 shows a blank blank;

Fig. 2 shows a finished molded part in the front view in the direction of arrow II in

Fig. 3;

3 shows the finished molded part in the view from below in the direction of the arrow III in Fig. 2.

Fig. 4 shows the finished molding in the side view from the left in the direction of

Arrow IV in Fig. 2; Fig. 5 is an opened mold for producing the molding shown in Figs. 2 to 4.

DESCRIPTION OF PREFERRED EMBODIMENTS In Fig. 1, a flat blank 1 is shown, which has been worked out of a plastic board, for example by cutting or milling. The contour edge 10 of the blank 1 limits the geometric development of one producing finished molded part in the plane of the board. Dot-dash

Double lines A, B, C denote the folded edges, along which the blank is bent during forming. The folding edges A, B and C divide the blank 1 into a plurality of surface areas, namely into a lower front surface area 12, a laterally upper front surface area 14, a floor area 16 and a left side area 18.

The blank 1 is first heated so far that the matrix material of the

Plastic is soft and deformable. Thereafter, the blank is in a

Inserted mold and along the adjacent to the bottom area double lines A and C by a predetermined angle, in the present case by 90 °, folded. Subsequently, the blank 1 is still bent to the double line B and thus receives its final shape shown in FIGS. 2 to 4. 2, 3 and 4, which show different views of the finished molded part, the folding edges A, B and C and the beveled surface portions 12, 14, 16 and 18 are shown.

Fig. 5 shows a mold for carrying out the method of the present invention. The molding tool has a punch 2 as an upper tool and a die 3 as a lower tool.

The die 3 comprises an immersion frame 30, in which a sprung bottom 32 is mounted so displaceable that the sprung bottom 32 acted upon by a compressive force of the punch 2 against a spring force in the immersion frame 30 hineinschiebbar.

The top side 34 of the sprung bottom 32 forms a negative mold with two recesses 36, 38 which are each bounded by a shaped edge 35 and 37 against the raised portion of the top 34 of the sprung bottom 32. The shape edges 35, 37 correspond in their contour to the edge portions 16 ', 16 "of the bottom region 16 of the blank 1.

The blank 1 is placed with its bottom portion 16 on the top 34 of the sprung bottom 32 so that the two parts of the bottom portion 16 come to lie in the recesses 36 and 38, respectively. The edge 16 'of the bottom portion 16 rests against the shaped edge 35 of the recess 36 and the edge 16 "of the bottom portion 16 rests against the shaped edge 37 of the recess 38. Subsequently, the punch 2 is moved against the die 3, so that the lower Face 20 of the punch 2 rests on the top 34 of the sprung bottom 32 and the bottom portion 16 of the blank 1. The blank 1 is fixed in this way in the mold.

The punch 2 is provided at its front in Fig. 5 side 22 with a large recess 24 which is bounded by an outer edge 23 to the raised portion of the front side 22 of the punch 2. Within the recess 24, a further raised portion 26 is provided, which is bounded with respect to the recess of an inner mold edge 25. The front side 22 of the punch 2 is provided with a further depression 28, which is delimited from the non-recessed region of the front side 22 by a lateral shaping edge 27.

The left side 21 of the punch 2 in FIG. 5 is provided with a lateral depression 29, which is delimited from the non-recessed region of the left side 21 by a lateral shaping edge 29 '. The recesses 28, 29 merge into one another.

If the punch 2 is moved further downwards in the direction of the arrow P against the elastic force of the sprung bottom 32, then the sprung bottom 32 together with the punch 2 dips into the immersion frame 30 of the die 3. The blank 1 clamped between the upper side 34 of the die 3 and the underside 20 of the punch 2 is then removed from the peripheral edge 31 of the

Insertion frame 30 forced upward, wherein the blank along the in Fig. 1 shown double lines A and C is bent. Upon further immersion of the punch 2 in the immersion frame 30, the lower front surface portion 12 of the blank lies in the recess 24 on the front side 22 of the punch 2 and the left side portion 18 of the blank 1 settles in the lateral recess 29 of the punch second

After the punch 2 is immersed in the immersion frame 30 of the die 3, the side-upper front surface portion 14 of the blank 1 by means of a slide (not shown) along the double line B in Fig. 1 about the edge portion shown in FIG Stamp 2 bent so that the laterally upper front surface area 14 comes to lie in the recess 28 of the punch 2.

In this submerged position, the outer peripheral edge 12 'of the lower front surface portion 12 of the blank 1 bears against the forming edge 23 of the front side 22 of the punch 2 and the inner forming edge 12 "of the lower

Front surface region 12 bears against the shaped edge 25 of the raised portion 16 of the front side 22 of the punch 2. The outer peripheral edge 18 ^{* of} the left side portion 18 of the blank 1 abuts against the lateral forming edge 29 'of the punch 2 and a lower portion 14' of the laterally-upper front surface portion 14 of the blank 1 comes against a

Section of the mold edge 27 to the plant. The shaped edges 35, 37 in the die 3 and the shaped edges 23, 25, 27 and 29 'of the punch 2 thus form true-to-scale boundaries for the finished molding, which is removed after cooling of the mold from this. The finished molded part thus corresponds to the predetermined dimensions defined by the depressions 36, 38 in the die 3 and the depressions 24, 28, 29 of the punch 2, so that the finished molded part no longer has to be trimmed. During the forming step, thus, edge portions are supported

Peripheral edge 10 of the blank against provided in the mold and forming edges from abutment surfaces, thereby ensuring that the edge portions occupy a defined spatial position after forming the blank 1, which corresponds to a nominal dimension of the finished molded part. As a result, a reworking of the edges of the finished molding is no longer necessary.

Reference signs in the claims, the description and the drawings are only for the better understanding of the invention and are not intended to limit the scope.

LIST OF REFERENCE NUMBERS

They denote:

1 blank

2 stamps

3 matrix

10 forming edge

12 lower front surface area

14 side-upper front surface area

14 lower section of 14

16 floor area

18 left side area

20 bottom of 2

21 left side of 2

22 front side of 2

23 outer edge of shape

24 deepening

25 inner shape edge

26 raised area

27 shaped edge

28 deepening

29 deepening

29 shaped edge

29 edge section

30 immersion frames

31 peripheral edge

32 sprung ground

34 top of 32

35 shape edge

36 deepening

37 shaped edge

38 deepening

A, B, C folding edges

Claims

claims

1. A method for the production of molded plastic parts comprising the steps of: a) providing a plastic material having a board; b) processing the blank to produce a blank with a

Contour, which corresponds to the development of the finished molded part in the plane of the board;

c) heating the blank;

2. The method according to claim 1,

characterized,

the plastic material is fiber-reinforced, in particular reinforced with carbon fibers, and has a thermoplastic matrix material, in particular PPS.

3. The method according to claim 1 or 2,

characterized,

that the processing of the board in step b) takes place by chipless and / or machining operations.

4. The method according to any one of the preceding claims,

characterized,

the heating of the blank in step c) takes place by heat conduction.

5. Method according to one of the preceding claims,

characterized, that the molded part formed in step d) remains in the closed mold for a predetermined period of time and that during this period the temperature of the mold and thus of the molded part is cooled down to a predetermined temperature before the finished molded part is removed from the mold.

6. mold for performing the method according to one of

previous claims,

characterized,

in that the molding tool has at least one die and at least one

Stamp has, which are movable relative to each other, wherein the punch and / or the die has contact surfaces for at least one of the edges of the blank to be formed.