FR3075087A1 - TOOLING FOR MOLD OF OVERMOLDING - Google Patents

Abstract

 Tool (3) for bi-material or tri-material mold of an element (12) to be overmolded, comprising:  - first holding means (4) adopting a closed holding position or at least one open position,  - second holding means (5) independent of the first holding means (4) and adopting a closed holding position or at least one open position, the first and second means (4, 5) being able to be implemented sequentially , to maintain in position in the mold the element (12) during the injection phase of a first injection material providing a first overmolded part (10), then the second holding means (5) are intended once in their closed holding position to hold in position in the mold the first overmolded part (10), while the first holding means (4) are intended to be opened while keeping the second means (5) in the closed position.

Description

TOOLING FOR OVER-MOLDING MOLD

The invention relates to a tool for molding parts according to at least one plastic bi-injection, more particularly a tool for overmolding in bi-material or tri-material.

The invention will be more particularly described with regard to a bi-material overmolding, without however being limited thereto.

Certain plastic-based parts, for example in the automotive field, comprise two molding materials and a coating film covering at least one face of the body made of the two materials. To avoid joining the film by gluing on the body made of two materials, since in particular providing an unsightly rendering, the overmolding technique could be used by placing a film, intended to constitute the coating film, in the imprint of a mold.

Bi-material injection and overmolding techniques are well known. However, they sometimes impose constraints on the design of the means of implementation for certain types of parts to be manufactured, such as the aforementioned parts with a coating film. It is indeed necessary to keep the film in place during the injection of plastics. However, to achieve this maintenance, the means implemented today systematically generate a mark of maintenance on the film.

The object of the invention is therefore to propose a tool which makes it possible to overmold an element, such as a film, with at least two plastic injection materials, without leaving a mark or trace of retention on the film and on the molded part. obtained.

According to the invention, the tooling for a mold of an element to be overmolded, in particular for a bi-material or tri-material overmolding mold, comprises:

first holding means adopting a closed holding position or at least one open position, second holding means independent of the first holding means and adopting a closed holding position or at least one open position, the first and second means being suitable to be implemented sequentially so that the first holding means are intended to be closed to maintain in position in the mold the element to be overmolded during the injection phase of a first injection material which provides a first part overmolded, then preferably during the opening of the mold, and until the implementation of the second holding means in the closed position, the second holding means being intended once in their closed holding position to be held in the position molds the first overmolded part, while the first holding means are intended to be opened while keeping the second means in the closed position for injecting a second injection material.

The material injected during the second injection may or may not be the same material as that of the first injection.

According to one characteristic, the first holding means comprise at least one movable holding piece between a closed position and at least one open position, in particular said at least one piece being movable by pivoting, preferably the first holding means comprise several pieces of mobile supports which are arranged on the periphery of an imprint of a matrix intended to be the matrix of a mold.

Advantageously, the retaining part comprises a functional retaining part and an actuatable part for its mobility, the tooling comprising respectively separate maneuvering / actuating means for respectively closing and opening the part, the closing actuating means cooperating. by vertical translation at the bottom of the part, while the opening means are arranged above the part and are capable of acting by pushing on the opening actuating means.

According to another characteristic, the tool comprises separate closing and opening actuation means for respectively closing and opening the first holding means, preferably the opening actuation means being able to cooperate with the closing actuation means.

According to another characteristic, the tool comprises means for actuating the closure of the first holding means, preferably the means for actuating the closure being actuated pneumatically or hydraulically of the type at least one pneumatic or hydraulic piston, in particular the closure actuating means being intended to be housed, in the position of use of the tool in a mold, in particular in a die of the mold.

According to yet another characteristic, the tool comprises means for actuating the opening of the first holding means, preferably mechanically actuable, such as forming at least one spring plunger, preferably the opening actuation means being intended to be housed in the position of use of the tool in a mold, in particular in a mold punch.

Advantageously, the tool comprises locking means able to block in a static position the opening actuation means of the first holding means, in particular the locking means being a locking system with a stick.

According to another characteristic, the second holding means form at least one weight, such as a metal block, preferably the second holding means being mechanically actuable, in particular the second holding means being intended to be housed in the position of use of tools in a mold, in a mold punch.

Advantageously, the first holding means comprise one or more profile surface surfaces adapted to the element to be overmolded.

The invention also relates to a mold comprising a tool of the invention. According to one characteristic, the mold comprises at least one matrix and at least two punches cooperating sequentially with the matrix, the first punch cooperating with the matrix for a first overmolding, and the second punch cooperating with the matrix to carry out a second overmolding once the first punch and the die disengaged from each other and no longer facing each other, the first holding means being housed in the die while the second holding means are housed in the second punch.

Finally, the invention relates to an overmolding process implemented by the aforementioned mold of the invention, the process comprising the following steps:

arranging an element to be overmolded in the imprint of the matrix;

put the first holding means on the element in the closed position,

- close the mold with the first punch and inject a first injection material to make a first overmolding;

open the mold and position the matrix and the second punch opposite;

- Close the second holding means to come and maintain the first molding;

- while closing the mold, open the first holding means;

once the mold is closed, inject a second injection material onto the element to be overmolded at the level of the surface or surfaces which were held by the first holding means;

open the mold to unmold the finished overmolded part

In the following description, the terms "horizontal", "vertical", "upper", "lower", "high", "low" are used in the context of a normal installation of the mold, that is to say ie relating to a vertical concept with respect to a horizontal plane on which the matrix of the mold is placed.

The present invention is now described using examples which are only illustrative and in no way limit the scope of the invention, and from the attached illustrations, in which:

Figure 1 shows a molded part according to the invention which is still arranged in the mold of the mold after manufacture;

FIG. 2 illustrates a perspective view of part of a mold, in particular the die, and part of its tooling according to the invention, the element to be overmolded which is in the form of a film being arranged in the matrix in position held by the tool;

Figure 3 is a schematic partial sectional view of the closed mold and its tooling according to the invention at the end of the first overmolding and showing a holding part in the closed position;

Figures 4 to 8 are schematic sectional views of the mold and its tools showing the implementation of a holding part according to different stages of the molding manufacturing process according to the invention.

FIG. 1 illustrates a part 1 obtained by the mold of the invention, the part comprising at least two contiguous parts 10 and 11 made respectively of two different plastic materials, and a covering film 12 secured to a face common to the two parts . The joining of the film was obtained by overmolding by successively injecting the two plastic materials using the mold 2 of the invention and its tools allowing the film to be kept firm and precise during overmolding without leaving a mark either on the film or on the part at the end of production.

The tool 3 illustrated in part in Figures 3 to 8 and associated with the mold 2 (inside the mold), is intended to be integrated at different locations in the mold as visible in Figure 2 to maintain an element to be overmolded. different places in the mold.

The mold 2 comprises a matrix 20 with an imprint 21 in which the film 12 is intended to be positioned, a first punch 22-1 intended to cooperate with the matrix 20 in the closed position of the mold and during the injection of the first material plastic (Figures 3), and a punch 22-2 intended to cooperate with the die 20 in the closed position of the mold (Figure 8) and during the injection of the second plastic material. Transfer means by rotation or translation not shown make it possible to position the die 20, after the first injection and opening of the mold, opposite the second punch 22-2 for the second injection.

According to the invention, the mold 2 comprises the tool 3 which allows:

• keep film 12 in position:

- once the film has been deposited in the imprint 21,

- during the first injection in the closed position of the first punch 22-1 against the die 20 of the mold, and

- Once the mold is open and during the transfer of the matrix 20, thus ensuring the maintenance in position of the whole of the film 12 and of the first injected part 10 which is secured to said film, and called the first molding; then • to maintain in position the first part 10 integral with the film 12:

- once the die 20 opposite the second punch 22-2, and

- during the second injection in the closed position of the second punch 22-2 against the die 20 of the mold.

According to the invention, the tool 3 comprises first means 4 for holding the film and second means 5 for holding the first molding which operate sequentially after the first holding means 4.

The first holding means 4 are movable between a so-called closed position which corresponds to a position of contact with the film 12 (Figures 2 and 3) and of firm holding thereof, and a so-called open position (Figures 6 to 8) for which they are released from the film and are therefore no longer in contact.

In the embodiment illustrated by way of example, the first holding means 4 are movable while being retractable by pivoting. They comprise at least one retaining part 40.

As illustrated in FIG. 2, the tool comprises several holding pieces 40 distributed over the periphery of the imprint 21 of the matrix to hold the film 12 in several places. The number of parts depends in particular on the size of the element (the film) to be overmolded.

A retaining piece 40 has a horizontal pivot axis 41 and has a first distal end 42 provided with an applied surface 43 intended to cooperate with the film 12 according to a tight support to maintain the film, and a second end distal 44, opposite the first and which is capable of being actuated to ensure the pivoting of the part.

The surface of the surface 43 is adapted according to the type of element to be overmolded, in order to firmly hold the element without damaging it and to provide a contiguous contact to avoid any insertion of material during the first injection on the portion of film not to be overmolded with the first material.

In addition, the first punch 22-1 is also designed to present, of course, the appropriate volume corresponding to the volume of the first molding part 10, and provide one or more cavities 23 (FIG. 3) making it possible to house one or more parts 40 in closed position of the mold, the walls of each cavity being contiguous with the lateral faces of each part. Each piece is thus sandwiched in the closed position of the mold between the punch and the die. In the example illustrated, the film being a thin surface, the surface of the surface 43 is adapted to allow a firm hold without pinching. The wall surface 43 follows the profile of the cavity 21 of the matrix 20. In particular, the distal holding end 42 has a nose with a skewed wall surface 43.

Preferably, the part 40 can be actuated so as to close on the one hand and open on the other hand, via respectively separate maneuvering / actuating means. In the illustrated embodiment, the tool 3 comprises closing actuation means 6 which cooperate with the actuable distal end 44 while being movable by vertical translation at the level of the underside of the part 40, and opening means 7 which, arranged above the part 40, are capable of acting on the first actuation means 6.

The closing actuation means 6 are associated / housed in the matrix 20.

The opening means 7 are associated / housed in the second punch 22-2.

By way of example, the closing actuation means 6 are a pneumatic or hydraulic piston which rises from a low end position for which the part 40 is open (FIG. 7) to a high position for which the part 40 is closed (Figures 3 to 5). The rise of the piston 6 which is connected to the distal end 44 makes the part 40 pivot by pivoting.

By way of example, the opening means 7 are implemented mechanically when the mold is closed. They comprise a pusher 70 with compression spring 71. The free termination 72 of the pusher opposite the spring 70 is intended to come to bear on the upper termination of the piston 6 (FIG. 5). As the mold closes, the die 20 then being opposite the second punch 22-2, the pusher 70 pressing the piston 6, lowers the latter causing the part 40 to pivot in the opposite direction, and therefore causing it to open (Figures 6 and 7). In the closed position of the mold, the piston 6 is found in the low position.

Furthermore, the second punch 22-2 comprise cavities 24 adapted to accommodate the parts 40 in the open position while the mold is closed.

For safety, to guarantee locking of the opening means 7 in the static position, that is to say when the pusher must be stationary (FIG. 4), the mold being completely open, the tool comprises locking means 8 cooperating with the opening means 7. These locking means 8 are for example a locking "stick" system: an element 80, independent of the pusher 70 and transverse to the longitudinal body of the pusher, is on the one hand, in position open of the mold, engaged in a groove 73 which is formed in the pusher 70, which ensures the blocking of the pusher, and on the other hand is able to leave the groove 73 by displacement, during the closing of the mold, which ensures the release, the element then cooperating with a recess 81 opposite the pusher (Figures 6 to 8).

Before the opening of the retaining piece 40 while the mold is open, the die being located opposite the second punch 22-2, the second retaining means 5 are implemented to come into firm contact with the first molding 10 (FIG. 5 ). The second holding means 5 form a weight, for example a metal block; they are actuated for example mechanically. The second holding means 5 are advantageously associated / housed in the second punch 22-2.

The invention also relates to a method of overmolding with the mold 2 and the tool 3 of the invention. The process steps and the implementation of the tooling and the mold are now described with reference to FIGS. 2 to 8:

FIG. 2 illustrates the open mold 2, the film 12 having been positioned in the cavity 21 of the matrix 20; the parts 40 are in the closed position while firmly holding the film.

The mold is then closed by bringing the first punch 22-1 against the die 20. The injection of the first plastic material is carried out.

FIG. 3 illustrates the mold in its closed position and after the first overmolding, the first injection part 10 being integral with the film 12.

The mold can then be opened.

The matrix 20 is then transferred opposite the second punch 22-2, which corresponds to FIG. 4; the parts 40 are always closed, in particular when the transfer is ensured by rotation of the matrix.

Then, with reference to FIG. 5, the punch 22-2 is lowered towards the die, the mold remaining ajar, so that the second holding means 5 come into abutment against the first molding part 10.

The first overmolding (part 10 and integral film 12) being then maintained, the first means 4 for holding the film (parts 40) can begin to be retracted. To this end, the gradual closing of the second punch 22-2 of the mold 2 is implemented (Figures 6 to 8). The closing of the mold causes on the one hand the release of the pusher 70 of the opening means 7 by the release of the element 80 of the locking means out of the groove 73, and on the other hand, the downward translation ( towards the matrix 20) of said pusher 70. The pusher 70 which presses on the piston 6, causes it to descend gradually, causing the pivoting of the associated part 40 which is gradually housed in the reception cavity 24. The cavity 24 of reception of the part 40 in the open position, and the walls associated with the cavity are designed so that after closing the mold (Figure 8), the cavity 21 is properly closed by the punch for the second injection molding.

Once the second part 11 has been molded, the mold 2 can be opened and the part 1 taken out.

Claims (12)

1. Tool (3) for mold of an element (12) to be overmolded, in particular for bi-material or tri-material overmoulding mold, comprising: - first holding means (4) adopting a closed holding position or at least one open position, - second holding means (5) independent of the first holding means (4) and adopting a closed holding position or at least one open position, - The first and second means (4, 5) being able to be implemented sequentially, so that the first holding means (4) are intended to be closed to maintain in position in the mold the element (12) to overmolding during the injection phase of a first injection material which provides a first overmolded part (10), then preferably during the opening of the mold, and until the implementation of the second holding means (5) in the closed position, the second holding means (5) being intended once in their closed holding position to hold in position in the mold the first molded part (10), while the first holding means (4) are intended to be open while keeping the second means (5) in the closed position. 2. Tool according to claim 1, characterized in that the first holding means (4) comprise at least one holding part (40) movable between a closed position and at least one open position, in particular said at least one part being movable by pivoting, preferably the first holding means (4) comprise several movable holding pieces (40) which are arranged on the periphery of an imprint (21) of a matrix intended to be the matrix of a mold. 3. Tool according to the preceding claim, characterized in that the part (40) comprises a functional holding part (43) and an actuatable part (44) for its mobility, the tool comprising maneuvering / actuating means respectively separate (6,7) for respectively closing and opening the part, the closing actuation means (6) cooperating by vertical translation at the level of the underside of the part (40), while the opening means (7) are arranged above the part (40) and are capable of acting by pushing on the closure actuating means (6). 4. Tool according to any one of the preceding claims, characterized in that it comprises separate closing and opening actuation means (6, 7) for respectively closing and opening the first holding means ( 4), preferably the opening actuation means (7) being able to cooperate with the closure actuation means (6). 5. Tool according to any one of the preceding claims, characterized in that it comprises closing actuating means (6) of the first holding means (4), preferably the closing actuating means (6) being pneumatically or hydraulically actuated of the type at least one pneumatic or hydraulic piston, in particular the closure actuating means (6) being intended to be housed, in the position of use of the tool in a mold, in particular in a mold matrix. 6. Tool according to any one of the preceding claims, characterized in that it comprises opening actuating means (7) of the first holding means (4), preferably mechanically actuable, such as forming at least one spring plunger, preferably the opening actuating means (7) being intended to be housed in the position of use of the tool in a mold, in particular in a punch (22-2) of the mold. 7. Tool according to the preceding claim, characterized in that it comprises locking means (8) able to block in a static position the opening actuating means (7) of the first holding means (4), in particular the locking means (8) being a locking man system. 8. Tool according to any one of the preceding claims, characterized in that the second holding means (5) form at least one weight, such as a metal block, preferably the second holding means (5) being mechanically actuable , in particular the second holding means (5) being intended to be housed in the position of use of the tool in a mold, in a punch (22-2) of the mold. 9. Tool according to any one of the preceding claims, characterized in that the first holding means (4) comprises one or more surface surfaces (43) of profile adapted to the element to be overmolded. 10. Mold (2) comprising a tool (3) according to any one of the preceding claims. 11. Mold according to the preceding claim, comprising at least one matrix (20) and at least two punches (22-1, 22-2) cooperating sequentially with the matrix, the first punch (22-1) cooperating with the matrix (20 ) for a first overmolding, and the second punch (22-2) cooperating with the matrix (20) to produce a second overmolding once the first punch (22-1) and the matrix (20) are released from one of the other and no longer facing each other, the first holding means (4) being housed in the die (20) while the second holding means (5) are housed in the second punch (22-2). 12. Overmolding process implemented by the mold according to one of claims 10 or 11, characterized in that it comprises the following steps: arranging an element (12) to be overmolded in the cavity (21) of the matrix (20); put the first holding means (4) on the element (12) in the closed position, - close the mold with the first punch (22-1) and inject a first injection material to make a first overmolding; open the mold and position the matrix (20) and the second punch (22-2) opposite; - Close the second holding means (5) to come and hold the first overmolding; - while closing the mold, open the first holding means (4); once the mold is closed, inject a second injection material onto the element to be overmolded at the level of the surface or surfaces which were held by the first holding means (4); open the mold to unmold the finished overmolded part.