WO2013093064A1

WO2013093064A1 - Method for producing a thick-walled plastic part

Info

Publication number: WO2013093064A1
Application number: PCT/EP2012/076779
Authority: WO
Inventors: Wolfgang Kemper
Original assignee: Astroplast Kunststofftechnik Gmbh & Co. Kg
Priority date: 2011-12-23
Filing date: 2012-12-21
Publication date: 2013-06-27

Abstract

The present invention relates to a method for producing a thick-walled plastic part (1) comprising the following steps: producing at least one core part (2) of a plastic material, in particular by injection moulding; and overmoulding the core part (2) with a plastic material in an injection mould to form an edge part (3) which encloses the contour of the at least one core part (2) in order to form the thick-walled plastic part (1).

Description

"Method for producing a thick-walled plastic part"

The present invention relates to a method for producing a thick-walled plastic part.

It is known that plastic components in many

Applications can substitute components made of other materials (for example, metal). Such plastic parts are characterized, inter alia, by a comparatively low

Weight and in particular due to the sometimes drastically increased in the past costs of metallic raw materials by relatively low production costs.

Especially in the production of thick-walled plastic components with a wall thickness of at least 5 mm, as they for reasons of stability and durability in many

Application areas are required, the cycle time is in the

Essentially determined by the wall thickness and changes according to the square of the wall thickness of the plastic component. Due to high cycle times, the clock rates in the known from the prior art method for producing thick-walled

Plastic parts relatively low.

The object of the present invention is to provide a method for producing a thick-walled plastic part by injection molding, in which the cycle time with respect to

known manufacturing method can be reduced.

The solution to this problem provides a method of the beginning

mentioned type with the features of claim 1. The

Subclaims relate to advantageous developments of the invention. An inventive method for producing a thick-walled plastic part comprises the steps

- Producing at least one core part of a

Plastic material, in particular by injection molding, and

- Overmolding the core part with a plastic material in a mold of an injection molding tool for forming a peripheral part, which encloses the contour of the at least one core part to form the thick-walled plastic part.

Due to the geometric and with respect to the manufacturing process also made under thermal aspects "division" of the total wall thickness of the plastic part, which is at least 5 mm, in at least one core part and an edge part result in comparison to those known from the prior art

Manufacturing processes in which the thick-walled plastic part is produced in one step with the desired wall thickness, significantly shorter cycle times. As a result, the clock rates and thus the cost-effectiveness of the method can be increased in a particularly advantageous manner. The main reason for this is that the sum of the two cooling times for the at least one core part and the peripheral part enclosing this is significantly shorter than the cooling time of a thick-walled one

Plastic component, if this is conventionally produced in one step with the desired wall thickness. This makes it possible that with the inventive method thick-walled plastic parts can be produced with the advantages of a thin-walled plastic part in terms of shorter cycle times. It is achieved by the method presented here to produce a thick-walled plastic part so that initially at least one core part, compared to the wall thickness of the finished thick-walled Plastic part may have a relatively small thickness is produced. This at least one core part is then overmolded with a plastic material to form the edge part, which has the desired contour of the plastic component, so that a homogeneous, thick-walled plastic component can be produced.

So that also thick-walled plastic components can be produced with relatively complex shapes and contours in an advantageous manner, is provided in a particularly advantageous embodiment, that a plurality of core parts is produced, which with the

Plastic material for molding the edge part to be encapsulated.

Several core parts can thereby at least partially

be created together and then with the

Plastic material to form the edge part are molded.

In order to increase the stability of the plastic part, it is proposed in a particularly preferred embodiment that the geometries of the at least one core part and the edge part are chosen so that the at least one core part and the edge part, in particular by undercuts, interlocking projections and depressions, at least partially geometrically penetrate.

As an alternative or in addition to the measure of the geometric penetration of the at least one edge part with the core part, in a further, particularly preferred embodiment there is the possibility that the at least one core part in the

Encasement with the edge part is heated or kept at temperature such that it is at least partially melted or remains melted. As a result, a very homogeneous connection of the at least one core part to the edge part can advantageously be obtained. The at least one core part is thus advantageously designed so that there is an intensive and homogeneous connection with the edge part. This can be done in particular by a corresponding geometry and geometric penetration of the at least one core part with the edge part and / or by a hot core as possible, which is up again or merged with the encapsulation with the edge part. A combination of

Geometry and temperature is particularly advantageous in this context.

Preferably, the at least one core part and the edge part of the same or at least equivalent in terms of their chemical and / or physical properties

Plastic materials are produced. This is what it is in

Advantageously possible, undesirable influences on the quality of the thick-walled plastic part, the heterogeneous

Material properties of the used for the production

Plastic materials can be, at least minimized as much as possible.

In an alternative embodiment, it is also possible that the at least one core part and the edge part

different plastic materials are produced. This allows deliberately heterogeneous material properties

different plastics are used to give the at least one core part and the edge part different properties. The choice of different materials can

especially with regard to the material quality, the

Material surface and / or haptics, the material strength, the

Material color, the degree of filling of the materials or the cost of the plastic materials. In a preferred embodiment, it is proposed that the thick-walled plastic part in a process step in a

Injection molding tool, in particular using a transfer, insert, or separation slide method is produced. The advantage of this embodiment is that the core part and the edge part in a single injection molding tool (and thus in a process step) can be produced successively without costly removal of the core part.

Alternatively, there is also the possibility that the thick-walled

Plastic part is produced in at least two process steps in at least two injection molds. In this case, in a first step, the at least one core part in a first

Injection molding tool produced as a pre-molded part. The encapsulation of the edge part takes place in the second process step in a second

Injection molding tool.

In a further advantageous embodiment it can be provided that the positions for the gating of the at least one core part and for the gating of the edge part are chosen differently. The production of the thick-walled plastic part in two or more process steps also leads to a different and primarily suitable choice of

Anspritzpositionen the orientation of the plastic material in the at least one core part and the edge part can be designed differently, so that in the plastic component by the at least one core part and the edge part in combination very high

Strength values can be achieved. This is especially true for fiber reinforced plastics, where the fibers can be oriented in different directions and layers (called "layers")

generate so-called weld lines in the plastic component, which weaken the strength of the plastic component and thereby adversely affect. Again, the influence of the weld line on the strength of the plastic component can be minimized in a particularly advantageous manner by the injection points are placed in the at least one core part and in the edge part of different, optimized in view of the achievable strength of the plastic component positions.

In a particularly preferred embodiment, it is proposed that in the manufacture of the at least one core part of this spacer means, in particular distance projections, spacer ribs or the like, are formed, which are such that they at least some core part of at least some walls and / or shape contours of a Mold cavity of the injection molding tool

can space. As a result, an optimized encapsulation of the at least one core part with the plastic material to form the edge part can be obtained. The distance means can in

be advantageously designed so that they can at least partially effect the above-mentioned geometric penetration of the at least one core part with the edge part.

By a suitable embodiment of the at least one core part and adaptation to the edge part, the shrinkage of the thick-walled plastic part produced by the method described here can be reduced in a particularly advantageous manner. It has surprisingly been found that the formation of cavities and vacuoles can advantageously be prevented or at least minimized by the method presented here. As a result, a controlled and increased strength of the plastic component can be achieved. This is on the one hand by the geometry of the at least one core part as well as by the selected in the production

Temperature level possible. Since shrinkage causes the inner, hot spots to fade particularly strongly, this can Phenomenon significantly reduced by the previous optimized production of the core part. In particular, the core part can be provided with a sprue optimized for the shrinkage and orientation of the plastic material. The at least one edge part is then produced with a sprue optimized for the surface, appearance and the automatic production process.

All measures to improve and influence the

Shrinkage and to prevent voids also have a particularly advantageous effect on the delay of

Plastic component. Again, by appropriate geometric and thermal "division" of the component in the at least one core part and the edge part of the delay of the plastic component can be selectively influenced.

The method described here can be realized in particular with the aid of a so-called tandem tool. In this case, the core part and the edge part can be produced both in one and in both tool levels. The tandem process ultimately leads to an extension of the cooling time, without the

Cycle time is significantly extended. Thus, the use of complex Nachkühlstationen or additional cooling sections, for example in a pool, advantageously no longer required.

Other features and advantages of the present invention will become more apparent from the following description

Embodiments with reference to the accompanying

Illustrations. Show in it

1a is a perspective view of a core part which is used in a preferred embodiment of a method for producing a thick-walled plastic part,

1b is a plan view of the core part of FIG. 1a,

1c shows a side view of the core part according to FIGS. 1a and 1b,

2 shows a perspective, highly simplified elevational view of a mold of an injection molding tool with the core part arranged in a mold cavity,

Fig. 3 is a perspective view of one according to the method

manufactured, thick-walled plastic part,

4 is a plan view of the plastic part of FIG. 3,

5 shows a section through the plastic part along a line A - A in Figure 4,

Fig. 6 shows a portion of a manufactured by the method

Plastic part, in which the core part and a peripheral part made of different plastic materials;

7 is a perspective view of a core part and a

Plastic component, which has the edge part. First, the basic steps of a

preferred embodiment of a method for producing a thick-walled plastic component 1 with a wall thickness of at least 5 mm are explained in more detail. Such a method comprises the steps

- Producing at least one core part 2, as shown by way of example in Fig. 1, of a plastic material, in particular by injection molding, and

- Overmolding of the core part 2 with a plastic material in an injection molding tool for forming an edge part 3, which is the contour of the at least one core part 2 to form the

encloses thick-walled plastic part 1.

The core part 2 which can be produced in particular by injection molding and whose external shape configuration is adapted in the present case to the outer contour of the thick-walled plastic component 1 which is shown in FIGS. 3 to 5, has in the present case a substantially cuboid shape with rounded corner regions 20, 21, 22, 23 and a central circular recess 24. The core part 2 has two longitudinal sides 25, 26 which are opposite one another and extend parallel to one another, and two likewise mutually opposite and parallel to one another

extending transverse sides 27, 28, which in the present case are shorter than the two longitudinal sides 25, 26. Furthermore, the core part comprises a first flat base surface 29a and a second flat base surface 29b, which likewise extend parallel to one another.

As can be seen in FIGS. 1 a to 1 c, each of the two planar base surfaces 29 a, 29 b of the core part 2 in this exemplary embodiment has four spacer projections 40, which in the present case are located near the rounded corner regions 20, 21, 22, 23 are formed on the base surfaces 29a, 29b. Likewise, each of the two longitudinal sides 25, 26 has two spacer projections 41, which are also formed in the vicinity of the rounded corner regions 20, 21, 22, 23 on the two longitudinal sides 25, 26. The distance projections 40, 41 may be formed in particular conical. In the central recess 24 of the core part 2 three spacer ribs 42 are formed in the present case, which extend over the entire depth of the recess 24 and are arranged offset by 120 ° to each other.

The spacer projections 40, 41 and the spacer ribs 42 form, from a functional point of view, spacer means which are designed to form the core part 2 of at least some walls 50 and / or mold contours 51 of a mold cavity 5 for molding the core part 2 with the plastic molding material an edge portion 3 used form 6 of an injection molding tool can space. By this measure, an optimized encapsulation of the core part 2 can be achieved with the plastic material. The two transverse sides 27, 28 have in the present case no spacer means, but can in principle also be provided with such.

In the in Fig. 2 schematically greatly simplified in one

In elevation shown mold 6 of an injection molding tool, the core part 2 with the plastic material for molding the edge part 3 is encapsulated, which encloses the contour of the core part 2 to form the thick-walled plastic part 1. The thus produced thick-walled plastic part with the core part 2 and this enclosing edge part 3 is shown in Fig. 3 to 5 in several different views. The plastic component 1, whose outer surface is formed by the edge part 3, which surrounds the core part 2, in this case also has an im

Essentially cuboid shape with rounded edges Corner areas 30, 31, 32, 33 and a central circular

Recess 34. The plastic component 1 has two opposing and extending parallel to each other

Long sides 35, 36 and two also two each other

opposite and extending parallel to each other

Transverse sides 37, 38, which in this case shorter than the two

Long sides 35, 66 are. Furthermore, the plastic component 1 comprises a first flat base surface 39a and a second flat base surface 39b, which likewise extend parallel to one another.

Preferably, the core part 2 and the edge part 3 can be produced from the same or at least with regard to their chemical and / or physical properties equivalent plastic materials. This makes it possible in an advantageous manner that undesirable influences on the quality of the plastic part 1, the heterogeneous material properties of the used for the production of the core part 2 and the edge part 3

Plastic materials can be, at least minimized as much as possible.

Alternatively, there is also the possibility that the core part 2 and the edge part 3 are quite deliberately made of different plastic materials. This allows very heterogeneous

Material properties are exploited to give the at least one core part 2 and the edge part 3 different properties. The choice of different materials can

especially with regard to the material quality, the

Material surface and / or haptics, the material strength, the

Material color, the degree of filling of the materials or the cost of the plastic materials. An example of a thick-walled plastic part 1, in which the (at least one) core part 2 and the edge part 3 are made of different plastic materials, is shown in FIG. In principle, the thick-walled plastic part 1 can also have, at least in sections, more complex, partially curved contours.

Due to the geometric and in relation to the production also thermal "division" of the entire wall thickness of the plastic part 1 in at least one core part 2 and a rim part 3 arise in the

Compared to known manufacturing processes in which the

Plastic part is produced in one step with the desired wall thickness, significantly shorter cycle times. The reason for this is that in the present case, the sum of the two cooling times for the core part 2 and the edge part 3 is significantly shorter than the cooling time of the component, if this in one step with the desired

Wall thickness is produced. This makes it possible that with the method presented here thick-walled plastic parts 1 with the

Advantages of a thin-walled plastic part with regard to shorter cycle times can be produced. With the method presented here it is possible to produce a thick-walled plastic part 1 so that at least one initially relatively thin

executable core part 2 is produced. This core part 2 is then in the manner described above with a plastic material to form the edge part 3, which has the desired contour of

Plastic component 1 has, overmolded, so that as a result, a homogeneous, thick-walled plastic component 1 can be obtained.

In order to increase the stability of the plastic component 1, the geometries of the core part 2 and the edge part 3 are preferably selected so that the at least one core part 2 and the edge part 3, in particular by undercuts, interlocking

Protrusions and depressions, at least partially geometrically penetrate. In the present case, this penetration takes place through the

Distance projections 40, 41 and the spacer ribs 42, which in the

Production of the edge part 3 of the plastic material encapsulated become. Preferably, the core part 2 may be heated or kept at temperature during the encapsulation with the edge part 3, that it is at least partially melted or remains fused. As a result, a very homogeneous and stable connection of the core part 2 to the edge part 3 can advantageously be obtained.

It can be provided that the positions for the gating of the at least one core part 2 and for the gating of the edge part 3 are selected differently. In an at least two-stage production process of the thick-walled plastic part 1, in which the core part 2 is produced in the form of a pre-molded part in a first step and the core part 2 is overmolded in a separate tool, this results in different and suitable choice of the Anspritzpositionen 9, 10th the orientation of the

Plastic material in the core part 2 and edge part 3 can be designed differently (see Fig. 7), so that in the plastic component 1 by the at least one core part 2 and the edge part 3 in

Combination very high strength values can be achieved. This is especially true in fiber reinforced plastics, where the fibers can be oriented in different directions and layers (called "layers").

Likewise, apertures, recesses 24, 34 or the like in the plastic component 1 so-called weld lines 7, 8 produce, which weaken the strength of the plastic component 1 and thereby adversely affect. Again, the influence of the weld lines 7, 8 can be minimized to the strength of the plastic component 1 in a particularly advantageous manner by the

Anspritzpositionen 9, 10 are placed in the core part 2 and the edge part 3 at different, optimized in terms of the strength of the plastic component 1 positions. This situation is in FIG. 7 illustrated in which the (symbolized by arrows here)

Anspritzpositionen 9, 10 are selected for the core part 2 and the edge part 3 so that they are offset by 180 ° to each other.

By a suitable design of the core part 2 and adaptation to the edge part 3 can in a particularly advantageous manner, the

Shrinkage of the plastic part 1 can be reduced. It has surprisingly been found that the formation of voids and vacuoles can be prevented or minimized by the method presented here in an advantageous manner. As a result, a controlled and increased strength of the plastic component 1 can be achieved. This is possible on the one hand by the geometry of the core part 2 and by the temperature level selected during production. As in the shrinkage, the inner, hot spots

tends to decrease particularly strongly, this phenomenon can be significantly reduced by the prior optimized production of the core part 2. In particular, the core part 2 with a for the

Shrinkage and orientation of the plastic material optimized sprue be provided. The one edge part 3 is then produced with a sprue optimized for the surface, optics and the automatic production process.

All measures to improve and influence the

Plastic component 1 off. Again, by suitable

geometric and thermal "division" of the plastic component 1 in the at least one core part 2 and the edge part 3 of the delay of the plastic component 1 are selectively influenced.

Claims

claims:

A process for producing a thick-walled plastic part (1) comprising the steps

- Producing at least one core part (2) from a

Plastic material, in particular by injection molding, and

- Overmolding of the core part (2) with a plastic material in an injection molding tool for forming an edge part (3) which encloses the contour of the at least one core part (2) to form the thick-walled plastic part (1).

2. The method according to claim 1, characterized in that a plurality of core parts (2) is produced, which with the

Plastic material for molding the edge part (3) are molded.

3. The method according to claim 1 or 2, characterized in that the geometries of the at least one core part (2) and the edge part (3) are chosen so that the at least one core part (2) and the edge part (3), in particular by Undercuts, interlocking projections and depressions, at least partially geometric

penetrate.

4. The method according to any one of claims 1 to 3, characterized

in that the at least one core part (2) heats up in such a manner during the encapsulation with the edge part (3)

or held at temperature that it is at least partially melted or

remains melted.

5. The method according to any one of claims 1 to 4, characterized

characterized in that the at least one core part (2) and the Edge part (3) of the same or at least in terms of their chemical and / or physical properties

equivalent plastic materials are produced.

6. The method according to any one of claims 1 to 4, characterized

characterized in that the at least one core part (2) and the edge part (3) are made of different plastic materials.

7. The method according to any one of claims 1 to 6, characterized

in that the thick-walled plastic part (1) is produced in a process step in an injection molding tool,

in particular using a transfer, insert, or isolation slide method.

8. The method according to any one of claims 1 to 6, characterized

characterized in that the thick-walled plastic part (1) in at least two process steps in at least two

Injection molding tools is produced.

9. The method according to claim 8, characterized in that the Anspritzpositionen (9, 10) for the gating of the at least one core part (2) and for the gating of the edge part (3) are chosen differently.

10. The method according to any one of claims 1 to 9, characterized

characterized in that in the manufacture of the at least one core part (2) on this spacer means, in particular

Distance projections (40, 41), spacer ribs (42) or

are formed, which are adapted to the at least one core part (2) of at least some walls and / or shape contours of a mold cavity of

Can space injection mold.