Method and apparatus for manufacturing components from a plastic-containing molding compound in a flow molding process

Abstract

Method for producing components (132) from a plastic-containing molding compound (128) in a flow-forming process in a mold chamber (102) of a molding tool (100), characterized in that the molding compound (128) is first made to flow outside the mold chamber (102) by means of the molding tool (100) under pressure, subsequently introduced into the opened mold chamber (102) by displacement and subsequently formed into a component (132) in the mold chamber (102) under further pressure, wherein the mold chamber (102) is closed.

Description

[0001] The invention relates to a method for producing components from a plastic-containing molding compound using an extrusion process in a molding cavity of a tool. Furthermore, the invention relates to a device for carrying out such a method, comprising a molding tool with molds that are displaceable relative to one another and define at least one openable and closable mold cavity, and pressing elements that are displaceable relative to one another and serve to cause the molding compound to flow outside the at least one mold cavity.

[0002] From DE 100 59 801 A1 a method is known for producing a fiber composite structure from a blank which can be consolidated by extrusion under the influence of heat and consists of at least one flowable fiber layer which is impregnated with the matrix system and restructured during extrusion, wherein the blank is constructed in several layers from at least one outer layer with a low fiber content and a structural layer with a comparatively high fiber content and the outer and structural layers are prefabricated in different sizes and / or flow capacities and are extruded together to form the finished component.

[0003] According to DE 100 59 801 A1, a stack of blanks is placed in a central region of a compression mold, and then the compression mold is closed and the structural and fiber layers are extruded under the influence of heat in such a way that the entire mold cavity of the mold is filled with fiber composite material, whereby a graded fiber content with a low fiber content on a concave component outer surface and a high fiber content in a remaining fiber composite material is maintained, whereupon a finished component can be demolded after an appropriate curing time.

[0004] The document DE 21 31 275 A relates to a device for producing components made of flow-formable material having a central part, a peripheral part and a plurality of radial parts extending radially from the central part.In order to improve the strength properties of the material used in the radial sections compared to the strength properties in any direction in the radial direction and to improve the strength properties of the material used in the peripheral section compared to the strength properties in any direction in the circumferential direction, the document DE 21 31 275 A proposes to provide a plurality of die parts which are displaceable relative to one another and which enclose a die cavity having a central section, radial sections and a peripheral section, wherein the die parts delimiting the radial sections are arranged displaceably relative to the other die parts such that the radial sections of the die cavity can be changed in size independently of the other sections of the die cavity.

[0005] Document DE 197 45 909 A1 relates to a device for the discontinuous compression or injection-compression molding of plastics in a cavity. To reduce the pressing forces, compression energies, and compression power required during the forming process of plastics, and thus save energy and equipment costs, document DE 197 45 909 A1 proposes designing at least two parts of the cavity surface to be movable, with at least one mold half containing one or more parts that move relative to it, and the relative movement of these parts transfers at least part of the forming energy into the plastic.

[0006] Document WO 2007 / 098628 A1 relates to a device consisting of a pressing tool and at least one mold cavity. In order to process thermoplastic or thermosetting molding compounds reinforced with long fibers in a fiber-friendly manner and thus achieve a high residual fiber length in the molded part, to compensate for volume fluctuations in the molding compounds or inserts, and to limit and compensate for uncontrolled pressure peaks in the mold cavity, document WO 2007 / 098628 A1 proposes designing the pressing tool as a two-piston press with two displaceable press pistons, wherein these two press pistons are arranged opposite one another within the cylindrical bushing of the pressing tool, and to arrange the mold cavity on the outer wall of the cylindrical bushing of the pressing tool.to arrange the mold cavities on the outer wall of the cylindrical bushing of the pressing tool in a circle, concentrically and at the same height, and to integrate them into this outer wall in such a way that the side wall of the press pistons at the height of the mold cavity or cavities simultaneously partially forms the wall of the mold cavity or cavities and closes off the mold cavity or cavities.

[0007] The invention is based on the object of structurally and / or functionally improving a device mentioned above. In particular, the maximum pressure occurring in the at least one molding cavity is to be reduced. In particular, the pressure occurring at the start of the extrusion process in the at least one molding cavity is to be reduced. In particular, the maximum pressing forces that occur are to be reduced. In particular, the pressure acting on an insert is to be limited. In particular, pressure-related damage to an insert is to be avoided. In particular, it is to be possible to press-fit pressure-sensitive inserts. In particular, the effort involved is to be limited. In particular, the retrofitting of an existing device with pressing elements is to be made possible. Furthermore, the method mentioned above is to be improved.

[0008] The problem is solved by a method having the features of claim 1 and by a device having the features of claim 4.

[0009] The device can be an extrusion press. The components can be automotive components. The components can be body components. The components can be node elements. The components can be hollow parts. The components can be profile parts. The components can each have at least one insert. The components can be made from a fiber composite material. The components can be made from a sheet molding compound (SMC). The fiber composite material can comprise a thermosetting reaction resin. The fiber composite material can comprise glass fibers. The molding compound can initially have a plate-like shape. The molding compound can have a dough-like consistency.

[0010] The tool can have at least two molds. The molds can be tool halves. The tool can have at least one parting plane. The at least one mold cavity can be used to form at least one component. The tool can be heated and / or cooled at least in sections. At least one mold can be heated and / or cooled at least in sections.

[0011] The tool has at least one displaceable pressing element. The tool can have at least one first pressing element and at least one second pressing element. The at least one first pressing element and the at least one second pressing element can form at least one parting plane. The parting plane of the at least one first pressing element and the at least one second pressing element can be at least approximately parallel to the parting plane of the tool. The at least one first pressing element and the at least one second pressing element can be arranged adjacent to the tool molds.

[0012] The pressing elements can delimit at least one pressing chamber communicating with the open mold space. The at least one first pressing element and the at least one second pressing element can delimit at least one pressing chamber communicating with the open mold space. The at least one pressing chamber can be openable and closable. The pressing elements can have dipping edges for sealing on the outside of the tool. The at least one first pressing element and / or the at least one second pressing element can have at least one dipping edge. The at least one dipping edge can serve to mutually guide the pressing elements. Closing the at least one pressing chamber can reduce the volume of the at least one pressing chamber. When the at least one pressing chamber is closed, molding compound present in the at least one pressing chamber can be displaced into the open mold space. At least one pressing element can be heated, at least in sections.

[0013] The tool molds, on the one hand, and the pressing elements, on the other hand, can be moved separately and / or in a coordinated manner. The device can have a control device for moving the tool molds and / or the pressing elements separately and / or in a coordinated manner.

[0014] The device can have at least one pressure generating device for applying pressure to the tool molds separately from the pressing elements. The pressure generating device can have at least one actuator, for example, at least one hydraulic cylinder. The pressure generating device can have at least one first actuator for applying pressure to a first tool mold. The pressure generating device can have at least one second actuator for applying pressure to a second tool mold.

[0015] At least one insert can be pressed into the mold cavity. The at least one insert can be a hollow part. The at least one insert can be a profile part. The at least one insert can be pressure-sensitive. With the tool open, the molding compound can first be arranged in at least one pressing chamber of the tool and at least one insert can be arranged in the mold cavity. Subsequently, a volume of the at least one pressing chamber can be reduced and the molding compound can be displaced into the mold cavity. Subsequently, the mold cavity can be closed and the component can be formed. The molding compound can initially have a plate-like shape. The molding compound can have a dough-like consistency. By reducing the volume of the pressing chamber, a viscosity of the molding compound can be reduced. The molding compound can be heated in the pressing chamber.

[0016] The components can be made from a fiber composite material. The components can be made from a sheet molding compound (SMC). The fiber composite material can contain a thermosetting reaction resin. The fiber composite material can contain inorganic fibers. The fiber composite material can contain glass fibers. The fiber composite material can contain organic fibers. The fiber composite material can contain carbon fibers. The fiber composite material can contain aramid fibers. The SMC material can initially have a plate-like shape. The SMC material can have a dough-like consistency.

[0017] In summary, and in other words, the invention thus provides, among other things, a compression molding process for overmolding insert components. In a mold concept, additional pressing surfaces can be incorporated alongside an actual component cavity (or mold cavity). An SMC material can be positioned on these pressing surfaces, and from these pressing surfaces, the material can be injected into the component cavity through a combined compression molding process.

[0018] The invention reduces the maximum pressure occurring in the at least one mold cavity. The pressure occurring in the at least one mold cavity at the beginning of the extrusion process is reduced. Maximum pressing forces are reduced. The pressure acting on an insert is limited. Pressure-related damage to an insert is avoided. Even pressure-sensitive inserts can be overmolded. The cost is limited. Retrofitting a device with pressing elements is possible.

[0019] An exemplary embodiment of the invention is described in more detail below with reference to the figures. Further features and advantages will become apparent from this description.

[0020] They show schematically and by way of example: Fig. 1 a pressing tool with an open mold chamber and separate open pressing chambers, Fig. 2 a pressing tool with an open mould chamber and separate pressing chambers acted upon in the closing direction, Fig. 3 a pressing tool with an open mould chamber and separate closed pressing chambers and Fig. 4 an extrusion press with a tool with a closed mold cavity.

[0021] Fig. 1 shows a pressing tool 100 with an open mold space 102, a first pressing space 104 separate from the mold space 102 and a second pressing space 106 separate from the mold space 102.

[0022] The pressing tool 100 has a lower tool half 108 and an upper tool half 110. The lower tool half 108 has a first tool mold 112 and first pressing elements 114, 116. The upper tool half 110 has a second tool mold 118 and second pressing elements 120, 122. The tool can be opened by moving the lower tool half 108 and the upper tool half 110 away from each other. The tool can be closed by moving the lower tool half 108 and the upper tool half 110 towards each other. The first pressing elements 114, 116 and the second pressing elements 120, 122 have plunge edges on the outside of the tool. This guides the lower tool half 108 and the upper tool half 110 against each other, and the pressing chambers 104, 106 are tightly closed to the outside. When the tool is opened, the first pressing chamber 104 and the second pressing chamber 106 are opened.When the tool is closed, the first pressing chamber 104 and the second pressing chamber 106 are closed.

[0023] The lower tool half 108 has a first pressure cylinder 124 for pressurizing the first tool mold 112. The first pressure cylinder 124 can be used to pressurize the first tool mold 112 independently of the first pressing elements 114, 116. The upper tool half 110 has a second pressure cylinder 126 for pressurizing the second tool mold 118. The second pressure cylinder 126 can be used to pressurize the second tool mold 118 independently of the second pressing elements 120, 122. The first pressure cylinder 124 and the second pressure cylinder 126 can close the mold chamber 102 independently of the first pressing chamber 104 and the second pressing chamber 106.

[0024] To produce a hollow component from a fiber composite material, an SMC material 128 is first introduced into the open compression chambers 104, 106 with the mold halves 108, 110 open. The SMC material 128 is, for example, plate-shaped and has a dough-like consistency. The SMC material 128 comprises a reactive resin and a fiber filling. Furthermore, a hollow insert 130 is first introduced with the mold halves 108, 110 open.

[0025] Below, as in Fig. 2, the mold halves 108, 110 are closed. The compression chambers 104, 106 are pressurized in the closing direction, and the volumes of the compression chambers 104, 106 decrease. The mold chamber 102 remains open. The SMC material 128 is pressurized, reducing the viscosity of the SMC material 128 and displacing the SMC material 128 from the compression chambers 104, 106 into the mold chamber 102, as shown by the arrows.

[0026] Fig. Figure 3 shows the pressing tool 100 with the mold cavity 102 still open and the compression chambers 104, 106 already completely closed. The entire SMC material 128 is located in the mold cavity 102 and surrounds the insert 130. Only a small press flash remains in the compression chambers 104, 106. Subsequently, the tool molds 112, 118 are moved toward each other using the pressure cylinders 124, 126, and the compression chamber 102 is closed to form a component. Due to the already reduced viscosity of the SMC material 128, the compressive load on the insert 130 is limited.

[0027] Fig. 4 shows the pressing tool 100 with closed mold cavity 102. As soon as the component 132 has reached sufficient strength, the tool halves 108, 110 are opened and the component 132 is removed. Reference symbol 100 extrusion press 102 Forming room 104 first press room 106 second pressing room 108 lower tool half 110 upper tool half 112 first tool mold 114 first pressing element 116 first pressing element 118 second tool shape 120 second pressing element 122 second pressing element 124 first printing cylinder 126 second printing cylinder 128 SMC material 130 insert 132 component

Claims

[1] Method for producing components (132) from a plastic-containing molding compound (128) in an extrusion process in a molding chamber (102) of a pressing tool (100), characterized by that the molding compound (128) is first caused to flow outside the molding space (102) under the action of pressure by means of the pressing tool (100), is subsequently introduced into the open molding space (102) by displacement and is subsequently formed into a component (132) in the molding space (102) under further pressure, wherein the molding space (102) is closed. [2] Method according to claim 1, characterized by that at least one insert part (130) is pressed into the mold space (102). [3] Method according to at least one of the preceding claims, characterized bythat, with the pressing tool (100) open, the pressing compound (128) is first arranged in at least one pressing chamber (104, 106) of the pressing tool (100) and at least one insert part (130) is arranged in the molding chamber (102), subsequently a volume of the at least one pressing chamber (104, 106) is reduced and the pressing compound (128) is displaced into the opened molding chamber (102) and subsequently the molding chamber (102) is closed and the component (132) is formed. [4] Device for carrying out a method according to at least one of the preceding claims, the device comprising a pressing tool (100) with tool shapes (112, 114) which are displaceable relative to one another and which delimit at least one openable and closable mold space (102), and pressing elements (114, 116, 120, 122) which are displaceable relative to one another and which serve to cause the molding compound (128) to flow outside the at least one mold space (102), characterized bythat the tool molds (112, 114) on the one hand and the pressing elements (114, 116, 120, 122) on the other hand can be displaced separately from one another and in a coordinated manner, so that the pressing compound (128) can be displaced into the at least one open mold space (102) and the mold space (102) can subsequently be closed to form a component (132). [5] Device according to claim 4, characterized by that the pressing elements (114, 116, 120, 122) delimit at least one pressing chamber (104, 106) communicating with the open mold chamber (102). [6] Device according to at least one of claims 4 to 5, characterized by that the pressing elements (114, 116, 120, 122) have dipping edges for sealing the outside of the tool. [7] Device according to at least one of claims 4 to 6, characterized bythat the device has at least one pressure generating device (124, 126) for applying pressure to the tool molds (112, 114) separately from the pressing elements (114, 116, 120, 122).

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