DE102010033675A1 - Method of overmolding and molding for its implementation - Google Patents

Abstract

The invention relates to the production of parts molded in particular of plastic, which combine at least two different materials and / or at least two material layers (19, 20). It uses an injection mold having a rotary section (4), which has shaping jaws (7, 8) which are brought successively to various locations distributed around the axis of rotation A of this section. Each shaping jaw (7, 8) has at least one element (13) which is movably mounted in a direction parallel to the axis of rotation A of the forming section. The movable member (13) is displaced so as to occupy, at a given position, a position different from the position taken at a preceding position with an offset (D), which determines the shape and / or dimensions of the forming volume the jaw (7, 8) modified.

Description

The present invention relates to a method for overmoulding, and more particularly to a method of overmolding that enables the production of parts molded in particular from plastic, which combine at least two different materials and / or at least two layers of material. The present invention also aims at a mold designed for carrying out the method of overmoulding, thus a mold having a movable rotary section.

In current techniques of automatic overmolding with rotation of a portion of the mold used, this mold portion remains in a fixed shape throughout the molding cycle. Such a concept does not make it possible to take account of the problem or the special functions associated with each position of the mold. In particular, the phenomenon of shrinkage of a first sprayed material prior to spraying a second material may not be considered. Because of these difficulties, manufacturing operations that require overmoulding are very often realized in different forms, with manual transfer of the parts between a mold in which a first material is injected and another mold in which a second material is injected.

The object of the present invention is to provide a method for overmolding and a mold for carrying out this method which avoid the above-mentioned drawbacks by providing a technically simple and less costly solution for rotary overmoulding which, inter alia, is disclosed. a. allows the compensation of the shrinkage of the injected material.

For this purpose, the invention primarily has a method for rotational overmolding for the production of parts molded in particular from plastic, which combine at least two different materials and / or at least two layers of material, the method using an injection mold with a rotary mold section, the shaping jaws, which is brought in the course of rotation of this mold section successively distributed around the axis of rotation of the mold section different locations, the method is characterized essentially in that each forming jaw of the rotary mold section has at least one element which in a rotation axis of this Molded portion is mounted movable parallel direction, wherein the element is displaced in this axial direction to take a position at a given position, which is different from the position assumed at a previous position so as to modify the shape and / or dimensions of the forming volume of the forming jaw.

The idea underlying the invention, in contrast to the usual conception of the rotary mold section, is thus to change the geometry of this rotary section according to the positions to adapt to each function of a particular position, irrespective of the number of positions: two Positions separated by 180 ° rotation, or three locations separated by 120 ° rotation, or four locations separated by 90 ° rotation. Each forming jaw of the rotary portion is formed identically to the other forming jaws, however, the axial mobility of an element of the forming jaw allows the shape and / or dimensions of the forming space of the forming jaw to be modified in accordance with the location occupied by this forming jaw.

Preferably, the movable element of each forming jaw of the rotary mold section is automatically positioned at each location by supports which become effective upon closure of the mold. In other words, various supports modify the axial position of the movable element of each forming jaw so that this element automatically positions each time the mold is closed to accommodate the function of a particular location.

The invention also has as its object an injection mold with a movable rotary section for the production of in particular plastic molded parts, which combine at least two different materials and / or at least two layers of material, the mold having a fixed section, a movable non-rotary section and a movable rotary portion having forming jaws capable of being successively brought to various locations distributed around the rotation axis of the mold portion in the course of rotation of the mold portion, the mold being characterized substantially by each mold jaw of the mold a rotary mold section has at least one element which is movably mounted in a direction parallel to the axis of rotation of this mold section, the element being displaceable in this axial direction to assume a position at a given position, which is determined by the is different at a previous position so as to modify the shape and / or dimensions of the forming volume of the forming jaw defined in combination with the fixed portion of the mold.

In a preferred embodiment of the injection mold, the movable non-rotary portion and / or the fixed portion of the mold in accordance with the forming jaws of the movable rotary portion staggered support areas, which cooperate with the movable elements of this forming jaw to the positions of the movable elements during of closing the mold.

In particular, the movable elements of the forming jaw may be fixedly connected to intermediate pieces which slidingly pass through respective passages formed in the movable rotary portion of the mold and which terminate at one and / or at the other of the ends of these passages the support areas or to interact with free spaces of the movable non-rotational portion and / or the fixed portion of the mold.

In the specific case of a mold intended for the production of parts in pot form with two or more successively molded material layers, the support regions are advantageously provided for displacing the movable element between the spraying of a first material layer and the spraying of a further material layer to offset, which is equal to the shrinkage of the first layer. Such a displacement makes it possible to align the second material layer exactly with the first material layer.

In the case of a mold intended for the production of parts of indifferent shape with two or more successively molded material layers, the support regions are more intended to displace the movable element by an amount between the spraying of a first material layer and the spraying of another material layer which is equal to the thickness of the further material layer. In other words, the displacement of the movable element generates the space required for spraying the second material layer. This application may involve the manufacture of parts in the form of wells.

In a variant of the foregoing case, in the case of a mold used for the production of parts of generally circular shape having a central portion made of a first material and a peripheral portion made of a second material is provided, the support portions are provided to offset the movable member between the spraying of the first material and the spraying of the second material by an amount which is equal to at least a fraction of the thickness of the peripheral portion.

In other words, after forming the central portion, the movable member causes a clearance leaving an annular space for squirting at least a fraction of the peripheral portion. This application may in particular relate to the manufacture of wheels or rollers with a rim or a hub of a first material and a peripheral tires of a second material.

The invention will be more fully understood by the following description with reference to the accompanying schematic drawing which shows, by way of example, some embodiments of this injection mold which correspond to the applications described above:

1 shows in section a mold according to the invention for the production of parts in pot form, wherein the mold is in the closed position,

2 shows on average the shape in 1 in an open position,

3 shows in section a mold according to the invention for the production of parts in the form of wells, wherein the mold is in the closed position,

4 shows on average the shape in 3 in an open position,

5 shows in section a mold according to the invention for the production of wheels with peripheral tires, wherein the mold is in the closed position,

6 shows on average the shape in 5 in open position.

In the various figures of the drawing, an injection mold is shown, which in a well known manner a fixed section 2 , a movable non-rotary section 3 and a movable rotary section 4 having, wherein these three mold sections 2 . 3 and 4 are arranged along a common axis A. The movable non-rotatory section 3 is translationally displaceable in the direction of the axis A, in this way to the fixed section 2 be moved towards or away from this. The movable rotatory section 4 is located between the fixed section 2 and the movable non-rotary section 3 ; he is through a middle wave 5 carried by a middle shaft bearing 6 of the movable non-rotary section 3 is translatable, and in particular is driven by a rotating base, as in the French patent FR 2 725 152 of the applicant is described. The movable rotatory section 4 thus can become the movable non-rotary part 3 can be moved toward or away from it, and can also rotate about the axis A when moving from the movable non-rotary section 3 is sufficiently spaced.

The movable rotatory section 4 has two identical, diametrically opposed forming jaws 7 and 8th on. These shaping jaws are two complementary shaping jaws 9 and 10 opposite, attached to the fixed section 2 the form are located.

In the application example of 1 and 2 the mold is intended for the production of parts in pot form, each part being made of an inner material layer 11 and an outer material layer 12 The result is the inner situation 11 completely covered.

Every shaping jaw 7 respectively. 8th of the movable rotary section 4 has an element 13 which is movably mounted in the direction of the axis A, wherein the element 13 has the general shape of a plate, with two or more intermediate pieces 14 is formed firmly connected. These latter glide through corresponding passages 15 passing through the movable rotary section 4 are formed. The element 13 in the form of a plate has a central opening through which a forming section 16 the cheek 7 or 8 passes, which corresponds to the inner shape of the parts to be formed.

The element 13 is thus in the direction of the axis A relative to the forming section 16 translationally displaceable.

The first shaping jaw 9 that are attached to the fixed section 2 of the form has a shaping shape, that of the outer surface of the inner material layer 11 corresponds to the parts to be formed. The second shaping jaw 10 that are attached to the fixed section 2 of the mold has a shaping shape, that of the outer surface of the outer material layer 12 the parts to be formed, in other words, corresponds to the outer surface of these parts.

The inner material situation 11 is in the interaction of one of the cheeks 7 respectively. 8th of the movable rotary section 4 with the first cheek 9 of the fixed section 2 shaped the shape. Subsequently, describes the movable rotary section 4 a rotation through 180 ° about the axis A and the outer material layer 12 is by interacting with the second jaw 10 of the fixed section 2 shaped the shape (see 1 , bottom half).

However, shrinkage of the material of the inner layer occurs 11 between the shaping point of this material and the shaping point of the outer material layer 12 on. This shrinkage results in an alignment problem of the inner material layer 11 with the outer material layer 12 , The mobility of the element 13 makes it possible to compensate for the amount of material shrinkage, as described below.

When forming the inner material layer 11 ( 1 , upper half) allow free space 17 located in the movable non-rotational section 3 the shape of the passages 15 are incorporated opposite, that the intermediate pieces 14 yourself to the section 3 can shift so that the movable member also to the movable non-rotary section 3 moved.

After opening the mold and rotating the movable rotary section 4 ( 2 ) find the spacers 14 in support against the main surface 18 of the movable non-rotary section 3 again ( 1 , lower half), what the element 13 towards the fixed section 2 the form by an amount D offset.

This amount D is equal to the amount of shrinkage of the material of the inner layer 11 chosen so that the material of the outer layer 12 as soon as it is sprayed, in perfect alignment with the material of the inner layer 11 located.

Provided that the shape described here has only two places, the finished molded part will be that resulting from the successive spraying of the two layers of material 11 and 12 results after opening the mold at the injection point of the outer layer 12 forming material ejected.

It can be seen that this outer situation 12 of the same material or of one in relation to the inner layer 11 different material can be.

In the application example of 3 and 4 the mold is intended for the production of cup-shaped parts, each part being made of a first material layer 19 , which gives this part its general form, and from a second material situation 20 results, which forms a middle disc, which is obviously only an example of a producible with the inventive method part.

At a first place ( 3 , upper half) is the spraying of the first layer 19 forming material.

After rotation of the movable rotary section 4 ( 4 ), the spraying of the second layer takes place 20 material, in a second place ( 3 , bottom half).

The first material situation 19 is made here with a small hole in its middle, through which the material of the second layer 20 is sprayed, allowing over-molding of the side opposite to the syringes.

Here, too, has every shaping jaw 7 respectively. 8th of the movable rotary section 4 an element 13 which is movably mounted in the direction of the axis A, and with intermediate pieces 14 Sliding through passages 15 go through in the movable rotary section 4 are formed, is formed firmly connected. The element 13 thus has an axial mobility, here for the successive molding of the two material layers 19 and 20 is designed.

In particular, the intermediate pieces are based 14 in the first place ( 3 , upper half) against the main surface 18 of the movable non-rotary section 3 off, so that the jaws of the fixed section 2 and the movable rotary section 4 to limit a mold cavity, that of the shape and the thickness of the first material layer 19 equivalent.

In the second place ( 3 , lower half) support the spacers 14 on a secondary surface 21 of the movable non-rotational portion which are relative to the main surface 18 by an amount D, the thickness of the second material layer 20 corresponds, is axially offset. The moving element 13 is thus offset, and it is generated a cavity, which is exactly the overformed second material layer 20 equivalent.

Each time the mold is closed, the movable element is positioned 13 the cheek 7 or 8th thus mechanically at the correct height (along the axis A), alternatively the first material layer 19 and the second material situation 20 to shape.

Again, with the proviso that the mold has only two places, the molded parts resulting from the successive spraying of the two material layers 19 and 20 result in the open position of the mold ejected at the second location.

Finally, the shape in the application example of 5 and 6 intended for the manufacture of parts of generally circular shape, such as wheels made of a rim 22 from a first material and a peripheral tire 23 are constructed of a second material.

The rim 22 is injected at a first location, and the tires 23 is overmolded in a second place. Always on the same principle have the shaping jaws 7 and 8th of the movable rotary section 4 the shape of each an axially movable element 13 which positions differently at the two locations to conform to the shaping of the first material and then the second material.

In particular, the intermediate pieces are based 14 in the first place ( 5 , upper half) against the surface 18 of the movable rotary section 6 from, and it is thus also defines a Formungskavität that of the rim 22 corresponds to that through a compound wreath 24 is complete with the rim 22 is connected by ribs (not visible in the drawing) forming punctiform connections. After rotation of the movable rotary section 4 ( 6 ) and due to the open spaces 25 of the movable non-rotary section 3 the movable element positions itself 13 different in that it is set back so as to limit a molding cavity, that of a tire to be overmoulded in a second spraying 23 corresponds to 5 , bottom half). The material of the tires 23 is thus completely around the connecting ring 24 injected, which makes it mechanical and not just by adhesion to the rim 22 is connected. It can be seen that in this application example, the axial displacement D of the movable element 13 between the two bodies only a fraction of the total thickness of the peripheral tires 23 is equal to.

As in the previous examples, the ejection of the finished part, ie in this case of the wheel takes place from the rim 22 and the tires combined with this rim 23 is constructed, in the second place when opening the mold.

• – dem beweglichen Element der Backen des beweglichen rotatorischen Abschnitts in Abhängigkeit der zu formenden Formgebungen jegliche Formgebungen verliehen werden,
• – die für die Positionierung des beweglichen Elements erforderlichen Abstützungen in jeglichen Formen realisiert werden,
• – die Anzahl an Stellen der Form erhöht werden, sei es um Teile herzustellen, die aus zahlreicheren Materialien und/oder Lagen geformt werden, sei es um über eine spezifische Auswurfstelle zum Auswerfen der fertigen Teile in der Schließstellung der Form zu verfügen,
• – das erfindungsgemäße Verfahren zum Herstellen von Teilen beliebiger Form und Bestimmung aus jeglichen formbaren Materialien bestimmt ist.

It is understood that the invention is not limited to the sole embodiments of this injection mold, which have been described above by way of example, but on the contrary comprises all variants of embodiment and application variants which follow the same principle. In particular, the scope of the invention is not abandoned if:

• The forming element of the jaws of the movable rotary section is given any shape as a function of the shapes to be formed,
• The supports required for the positioning of the movable element are realized in any shape,
• The number of points of the mold is increased, whether to produce parts formed of more numerous materials and / or layers, whether to have a specific ejection point for ejecting the finished parts in the closed position of the mold,
• - The inventive method for producing parts of any shape and destination is determined from any moldable materials.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• FR 2725152 [0021]

Claims (9)

Method for rotational overmolding for the production of in particular molded plastic parts, the at least two different materials and / or at least two layers of material ( 11 . 12 ; 19 . 20 ; 22 . 23 ), the method comprising an injection mold having a rotary mold section ( 4 ), the forming jaws ( 7 . 8th ), which in the course of the rotation of this mold section ( 4 ) successively around the axis of rotation (A) of the mold section ( 4 ) distributed different places, characterized in that each shaping jaw ( 7 . 8th ) of the rotary mold section ( 4 ) at least one element ( 13 ), which in one to the axis of rotation (A) of this mold section ( 4 ) is mounted movably in the parallel direction, wherein the element ( 13 ) is displaced in this axial direction to assume a position different from the position assumed at a previous position at a given position so as to obtain the shape and / or dimensions of the forming volume of the forming jaw ( 7 . 8th ). Method for overmoulding according to claim 1, characterized in that the movable element ( 13 ) each shaping jaw ( 7 . 8th ) of the rotary mold section ( 4 ) is automatically positioned at each point by supports that take effect when the mold is closed. Injection mold with a movable rotary portion for the production of parts molded in particular of plastic, the at least two different materials and / or at least two layers of material ( 11 . 12 ; 19 . 20 ; 22 . 23 ), the mold being adapted for carrying out the overmolding process according to claim 1 or 2, the mold having a solid section (FIG. 2 ), a movable non-rotational section ( 3 ) and a movable rotatory section ( 4 ), the forming jaws ( 7 . 8th ), which are able, during the rotation of the mold section ( 4 ) successively around the axis of rotation (A) of the mold section ( 4 ) distributed to be brought different places, characterized in that each shaping jaw ( 7 . 8th ) of the rotary mold section ( 4 ) at least one element ( 13 ), which in one to the axis of rotation (A) of this mold section ( 4 ) is mounted movably in the parallel direction, wherein the element ( 13 ) is displaceable in this axial direction so as to assume a position at a given position which is different from the position assumed at a preceding position so as to increase the shape and / or the dimensions of the shaping volume of the forming jaw ( 7 . 8th ), which in combination with the fixed section ( 2 ) of the form is defined. Injection mold according to claim 3, characterized in that the movable non-rotational section ( 3 ) and / or the fixed section ( 2 ) of the mold in accordance with the forming jaws ( 7 . 8th ) of the movable rotary section ( 4 ) offset support areas ( 18 . 21 ) connected to the movable elements ( 13 ) of the shaping jaws ( 7 . 8th ) interact with the positions of the moving elements ( 13 ) during closing of the mold. Injection mold according to claim 4, characterized in that the movable elements ( 13 ) of the shaping jaws ( 7 . 8th ) with spacers ( 14 ), which are gliding through corresponding passages ( 15 ) passing in the movable rotatory section (FIG. 4 ) of the mold are formed, and which at one and / or at the other of the ends of these passages ( 15 ) to communicate with the support areas ( 18 . 21 ) or with open spaces ( 17 . 25 ) of the movable nonrotatory section ( 3 ) and / or the fixed section ( 2 ) of the form. Injection mold according to claim 4 or 5, characterized in that it is a mold for the production of parts in pot form with two or more successively molded material layers ( 11 . 12 ), wherein the support areas are provided to the movable element ( 13 ) between the spraying of a first material layer ( 11 ) and spraying another material layer ( 12 ) by an amount (D) equal to the shrinkage of the first layer ( 11 ). Injection mold according to claim 4 or 5, characterized in that it is a mold for the production of parts with two or more successively molded material layers ( 19 . 20 ), wherein the support areas are provided to the movable element ( 13 ) between the spraying of a first material layer ( 19 ) and spraying another material layer ( 20 ) by an amount (D) equal to the thickness of the further material layer ( 20 ). Injection mold according to claim 4 or 5, characterized in that it is a mold for the production of parts of generally circular shape with a central portion ( 22 ) made of a first material and a peripheral portion ( 23 ), which is made of a second material, acts, wherein the support areas are provided to the movable element ( 13 ) between the spraying of the first material and the spraying of the second material by an amount (D) which is at least a fraction of the thickness of the peripheral portion ( 23 ) is equal to. Use of the injection mold according to claim 8 for the manufacture of wheels or castors with a rim ( 22 ) or a hub made of a first material and a peripheral tire ( 23 ) of a second material.

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