EP3174684A1

EP3174684A1 - System intended for positioning and retaining an insert in a mold and deactivatable upon ejection

Info

Publication number: EP3174684A1
Application number: EP15753123.7A
Authority: EP
Inventors: Olivier TORRES; Frédéric STABLO
Original assignee: Plastic Omnium SE
Current assignee: Plastic Omnium SE
Priority date: 2014-08-01
Filing date: 2015-07-23
Publication date: 2017-06-07
Also published as: CN106573400A; FR3024386B1; FR3024386A1; WO2016016550A1

Abstract

The invention relates to a system (4) for positioning and retaining an insert (3) in a mold (1) for forming a motor vehicle part (2) made of plastic (MP). Said system includes at least one partially overmolded insert (3) and comprises at least one retaining member (5) for retaining the insert (3) in place in a given position. Said system is characterized in that the retaining member (5) includes a member (6) for inserting an insert, and the inserting member (6) comprises a means (7) for locking the insert onto the retaining member (5) by translating the insert (3) in the direction of the inserting member (6).

Description

System for positioning and holding an insert in a mold, deactivatable on ejection

The present invention relates to the technical field of the manufacture of plastic parts for a motor vehicle, and in particular the field of insert overmolding for automotive parts.

More particularly, the invention relates to a system for positioning and holding in place an insert in a mold for overmolding inserts, a mold comprising this system, and a method of manufacturing a molded part using this mold.

In many industries and in particular in the automotive industry, hybrid parts are manufactured and used with a metal insert and a plastic part overmolded on the metal insert. It is also known to use during the overmoulding of plastic inserts.

In particular, construction elements can be made in the form of hybrid parts that can be of large dimensions such as technical front faces fixed to a motor vehicle structure, in a transverse arrangement, at the front of the engine.

The embodiment in hybrid form of elements such as front faces, has become a solution to meet requirements generally contrary to the properties of the structural element, for example the requirements of lightness and strength, in particular to shocks.

The embodiment in hybrid form also makes it possible to provide functionalization solutions for a plastic part.

For example, to securely assemble two pieces of plastics, it is known to use inserts, including metal, comprising a fastening means such as a thread (screw and / or tapped hole).

To integrate such inserts in a room, it is also known to report them after molding of the part by one or more operations in recovery (machining, drilling, punching, ...), before setting up the insert and of fix it by gluing or riveting, crimping, screwing.

This fixing method is binding for reasons:

- cost of recovery operations. Indeed this process requires different tools, additional equipment, manufacturing time and therefore a longer cycle time, and involves a loss of material,

hygiene and health because it can produce dust.

mechanical strength. Fixing the insert by this method is not suitable for all functions, such as towing for example. Moreover, it is known that a post-molding insert has a defect in precise positioning on the part, compared to the shapes of the molding.

There is indeed a loss of the "reference room", the fact that we leave the piece of the mold without the insert, then we have the room on a pose to add an insert. The lateral positions, in X and Y, are thus not very precise and the perpendicularity (angle) of the axis of a thread relative to the plane / faces of the part is not ensured.

However, the accuracy of the positioning of the insert on the part is important to be well interfaced with the vehicle. The aim of the invention is to remedy these drawbacks by providing a mold system enabling the precise positioning and maintenance of an insert in the cavity of this mold to form a plastic vehicle part comprising at least one insert, at least partially overmoulded, the system comprising at least one holding member for holding the metal insert in place in a given position, and in which:

- The holding member comprises a member for engaging the insert;

- The engagement member comprises a locking means of the insert on the holding member, by translation of the insert towards the body. According to the invention, the locking means may be a thread, preferably a fast thread such as a quarter-turn thread.

According to one embodiment, the system comprises around the engagement member, a sealing member adapted to surround the insert once engaged, the sealing member being composed of Peek® or Viton® material.

The invention also relates to a mold for forming a part of a motor vehicle made of plastic material comprising at least one partially overmolded insert.

This mold comprises at least one system for positioning and holding an insert according to the invention.

According to the invention, the positioning and holding system may comprise a disengaging means, allowing the engagement member to be stationary in rotation in the attachment position of the insert, and free to rotate in the position of ejection of the insert.

According to one embodiment, the engagement member is free in translation so as to be able to follow an ejection movement of the insert, to a locking position in which the engagement member becomes free to rotate. in order to release the insert.

According to another embodiment, the disengaging means comprises a ring cooperating with a notched cone carried by the engagement member to block the rotation of the engagement member during the introduction of the insert, the mold also comprising an ejector connected to the ring so as to release the ring of the notched cone, and allow a rotation of the engagement member when the insert is ejected.

The invention also relates to an assembly of an insert and a mold according to the invention, in which the engagement member constitutes a male or female element adapted to cooperate with a corresponding female or male element respectively on the insert.

The engagement member may comprise a thread cooperating with a thread of the insert.

The engagement member may constitute a threaded rod and the insert may then comprise a threaded hole cooperating with the threaded rod.

Conversely, the engagement member may constitute a tapped hole and the insert may comprise a threaded rod cooperating with the tapped hole.

The threads may be configured so that after engagement and locking of the insert on the engagement member, the insert bears tightly on the holding member sealing.

Finally, the invention also relates to a method of molding a motor vehicle part made of plastic material comprising at least one partially overmolded insert, in which the following steps are carried out using the mold according to the invention:

inserting the insert into the mold and engaging it in the engagement member;

the insert and the engagement member are locked by applying pressure to the insert in the direction of the engagement member;

the mold is closed and the insert is overmolded by injection of plastic material;

or opens the mold and ejects the piece carrying the molded insert.

The invention will be better understood on reading the appended figures, which are provided by way of examples and are in no way limiting, in which:

Figure 1 illustrates a mold according to the invention.

FIG. 2 illustrates in detail an example of the system for positioning and holding the insert according to the invention.

Figure 3 illustrates the various steps (a to d) of setting up and locking the insert on the holding member.

FIG. 4 illustrates the various stages (a to d) of removal of the insert relative to the holding member during an ejection phase of the finished part.

Reference is now made to FIG. The mold (1) according to the invention is a mold for forming a part (2) of a motor vehicle made of plastic (MP) comprising at least one insert (3). The insert (3) can be made of any material, including metal or plastic materials.

The mold (1) allows in particular partially overmold the insert (3). Overmolding is said to be partial when at least one surface of the insert remains visible after overmolding: the surface is not covered with plastic material (MP) during overmolding.

The mold (1) comprises a matrix (1 A) and a punch (1 B) delimiting at least the overmolding chamber (1 C) of the insert (3) and / or defining the cavity of the mold (1).

To prevent the insert (3) from moving during the molding of the plastic material (MP), the mold (1) comprises at least one system (4) for positioning and holding an insert in a mold. The positioning and holding system (4) is shown in detail in FIG.

This positioning and holding system (4), object of the invention, comprises at least one holding member (5), carried by the inner face of the punch (1 B) or the die (1 A), to maintain in place the insert (3) metal in a given position (Figure 3).

Figure 3 illustrates the establishment and locking of the insert (3) on the holding member. The insert (3) is thus maintained in a fixed position, and the mold (1) can be closed, then the plastic material (MP) is used, according to an injection molding or compression molding process. After opening the mold (1), the finished part (2) comprising the overmolded insert (3) is ejected from the mold (1), as shown in FIG.

The term "fixed position" means precise indexing (for each piece between the insert and the molding), repeatable (little dispersion between two parts) and reliable (the insert does not move during the molding) of the insert in the mold.

It is indeed not acceptable to position the insert (3) with a large indexing tolerance (greater than +/- 0.5mm), because the thread of the insert (3) must be very precisely placed to the correct place for the part (2) to be used on the vehicle.

According to the invention, the holding member (5) comprises an engagement member (6) of the insert (3). This member (6) allows to position the insert (3) without locking this commitment.

As illustrated in Figure 1, this engagement member (6) has a complementary shape of the insert (3) overmoulding, at a docking area. Thus, this engagement member (6) constitutes a male element (female) adapted to cooperate with a female element (respectively male) corresponding to the insert (3).

The engagement member (6) comprises a locking means (7) of the insert (3) on the holding member (5), the locking means (7) allowing a locking by a simple translation of the insert (3) towards the member (6), as indicated by the arrows in Figure 3B. In other words, a low force bearing on the insert (3) substantially perpendicular to the wall of the mold (1) carrying the holding member (5) is sufficient to lock the insert (3) on this member ( 5).

The locking means (7) can be:

a threaded system (end of the engagement member (6) in Fig. 2) for an insert having a threaded hole or a screw;

a bayonet system;

- a latching system;

an electromagnetic system for a metal insert.

These different locking means comprise a possibility of deactivating this locking.

In the case of a threaded system, the locking means (7) is deactivatable and preferably disengageable: the engagement member (6) is fixed in rotation when in position to receive the insert (3) ; it is however left free to rotate when in position to eject the insert (3). This clutch / clutch function is provided by a disengaging means (8).

According to one embodiment (not shown), during the ejection of the part (2) carrying the insert (3), the insert (3) which is locked by the locking member (7), drives with it at least the engagement member (6). The drive, opposite the face of the mold (1) carrying the holding member (5), is to a locking position, in which the engagement member (6) becomes free in rotation so as to release the insert (3).

According to another embodiment (shown in FIGS. 2 to 4), during the ejection of the part (2) carrying the insert (3), the ejector (11), or the ejection plate carrying all the ejectors of the mold, carries with it an element (10). The driving of this element releases the engagement member (6) in rotation. According to this embodiment, the disengaging means (8) can be constituted, in one example, by a notched cone (9) fixed on the rod of the engagement member (6) cooperating with a ring (10) surrounding the rod of the engagement member (6) and fixedly mounted in rotation but free in translation. During the insertion of the insert (3), the notched cone (9) is fitted into the ring (10), blocking its rotation (FIG. 2), and thus that of the stem of the body. commitment (6). During the ejection of the insert (3), the ring (10) is raised (towards the top of the cone) so as to release the notched cone (9). The rotation of the engagement member (6) is then possible (Figure 3) relative to the mold, and therefore, relative to the part containing the insert (3). Indeed, the insert (3) being locked in rotation after molding, on the finished part, it can not unlock in rotation because the part is in its footprint, and can not be rotated before ejection.

Preferably, the ring (10) is connected to an ejector (11) or to an ejection plate, present in the mold for ejecting the insert (3) at the end of the molding process. Thus, when the ejector (11) rises to eject the insert (3), it rises at the same time the ring (10), releasing the notched cone (9), and therefore, the rotation of the engagement member (6).

This system allows to have a holding member (5) which is always in a position suitable for receiving the insert (3). It is thus not necessary to rotate, that is to say an angular indexing or a particular alignment to these holding elements to ensure their function, because regardless of the position (in rotation) of the threaded axis, the insert can always engage and lock in the engagement member.

In the case of a bayonet system, or a latching system, the locking means (7) can also be disengageable.

In the case of an electromagnetic system for a metal insert, the locking means (7) can be deactivated by, for example, a power failure.

According to one embodiment, illustrated in Figures 2, 3 and 4, the insert has a threaded hole, and the locking means (7) is a thread, preferably located at the end of the engagement member (6). This thread is advantageously of the fast thread type and important step. Indeed, with this type of threading, a simple pressure of the insert (3) on the engagement member (6) rotates the insert (3), and the screwing is done on a quarter of the turn of the engagement member (6).

Such an insert (3), carrying a threaded hole not overmolded, can serve as a threaded fastener, for attaching another piece to the insert bearing part. This avoids drilling, riveting or crimping operations to fix two pieces. The thread of the insert (3) serving to cooperate with the thread of the locking means (7) may be the same as the thread used to fix another part on the part carrying the insert (3). According to another embodiment, the threading of the insert (3) serving to cooperate with the thread of the locking means (7) is different from the threading used to fix another part on the part carrying the insert.

The engagement member (6) thus constitutes a threaded rod carried by the holding member (5).

According to one embodiment (not shown in the figures), the insert (3) comprises a quarter-turn screw, and the locking means (7) is a quarter-turn thread. The engagement member (6) thus constitutes a tapped hole carried by the body of maintenance (5).

Preferably, the threads are configured so that after engagement and locking of the insert (3) on the engagement member (6), the insert (3) bears tightly against the holding (5), thus sealing. Indeed, the two threads, one on the engagement member (6), the other on the insert (3), allow on the one hand to maintain the insert (3) in a given position without have to perform rotation, and secondly, they allow to perform a tightening (a pull) of the insert (3) on the holding member (5), which allows to seal, thus avoiding the material (MP) overmoulding to enter the thread of the insert (3). The thread of the insert (3) can then perfectly fulfill its function of fixing a member to the workpiece carrying the insert.

To further improve the sealing, and according to a particular embodiment, the system (4) for positioning and holding an insert comprises, around the engagement member (6), a sealing element (12). ) adapted to surround the insert (3) once engaged. Preferably, this sealing element (12) comprises an element made of Peek® or Viton® material.

Advantageously, the positioning and holding system (4) may comprise along the engagement member (6) rings (13, 14) to avoid friction. These rings can be bronze or graphite.

Advantageously, the system (4) may comprise at its base needle bearings (15) to ensure the rotation of the engagement member (6), and thus compensate for the forces. The invention also relates to a method of molding a plastic vehicle part (2) comprising at least one partially molded insert (3), in which the following steps are carried out by means of the mold (1) according to the invention. invention:

the insert (3) is introduced into the mold (1) and is engaged in the engagement member (6);

the insert (3) and the engagement member (6) are locked by applying pressure to the insert (3) in the direction of the engagement member (6);

the mold (1) is closed and the insert (3) is overmolded by plastic injection (MP);

- Or opens the mold (1) and eject the part (2) carrying the insert (3) overmolded.

Claims

1. System (4) for positioning and holding an insert (3) in a mold (1) to form a part (2) of a plastic motor vehicle (MP) comprising at least one insert (3) partially overmoulded, said system (4) comprising at least one holding member (5) for holding the insert (3) in place in a given position, characterized in that:

- The holding member (5) comprises an engagement member (6) of an insert;

- The engagement member (6) comprises a locking means (7) of the insert on the holding member (5), by translation of the insert (3) in the direction of the engagement member (6).

2. System according to claim 1, wherein the locking means (7) is a thread, preferably a fast thread such as a quarter-turn thread.

3. System according to one of the preceding claims, comprising around the engagement member (6), a sealing member (12) adapted to surround the insert

(3) once engaged, the sealing element (12) being composed of Peek® material or Viton®.

Mold (1) for forming a part (2) of a motor vehicle (MP) comprising at least one insert (3) partially overmolded, characterized in that the mold (1) comprises at least one system (4) positioning and holding an insert (3) according to one of the preceding claims.

5. Mold (1) according to claim 4, wherein the system (4) for positioning and holding comprises a disengaging means (8), allowing the engagement member (6) to be immobile in rotation in fixing position of the insert (3), and free to rotate in the ejection position of the insert (3).

6. Mold (1) according to claim 5, wherein the engagement member (6) is free in translation so as to follow an ejection movement of the insert (3), to a position of blocking in which the engagement member (6) becomes free to rotate so as to release the insert (3).

7. Mold (1) according to claim 5, wherein the disengaging means (8) comprises a ring (10) cooperating with a notched cone (9) carried by the engagement member (6) to block the rotation of the engagement member (6) during the introduction of the insert (3), the mold (1) also having an ejector (11) connected to the ring (10) so as to release the ring (10). ) of the notched cone (9), and allow a rotation of the engagement member (6), during the ejection of the insert (3).

8. An assembly of an insert (3) and a mold (1) according to one of claims 4 to 7, wherein the engagement member (6) is a male or female element adapted to cooperate with a female element, or respectively male, corresponding to the insert (3).

9. The assembly of claim 8, wherein the engagement member (6) comprises a thread cooperating with a thread of the insert (3).

10. The assembly of claim 8, wherein the engagement member (6) is a threaded rod and the insert (3) has a threaded hole cooperating with the threaded rod.

11. Assembly according to claim 8, wherein the engagement member (6) constitutes a tapped hole and the insert (3) comprises a threaded rod cooperating with the tapped hole.

12. Assembly according to one of claims 9 to 11, wherein the threads are configured so that after engagement and locking of the insert (3) on the engagement member (6), the insert (3) is in tight support on the holding member (5) sealing.

13. A method of molding a part (2) of a motor vehicle made of plastic material comprising at least one insert (3) partially overmoulded, wherein the following steps are carried out by means of the mold (1) according to one of claims 4 to 7: - the insert (3) is introduced into the mold (1) and is engaged in the engagement member (6);