MOLD AND METHOD FOR OVERMOLDING A DISHWARE CONTAINER

Abstract

The invention relates according to a first aspect to a mold (10) for injection overmolding a dishware container (20) with a material comprising silicone, the mold (10) comprising a female part (12) and a male part (11), the female part (12) comprising: an imprint (13) configured to receive a first face (21) of the dishware container during overmolding, an injection nozzle (9) configured to allow the injection of the material comprising silicone into the imprint (13) on the first face (21), the male part comprising: a central stud (1) formed from a material having a Shore D hardness of between 50 and 60 or comprising a coating of a material having a Shore D hardness of between 50 and 60, configured to receive a second face (22) of the dishware container, a peripheral seal (3) formed from a material having a Shore A hardness of between 50 and 60, and configured to receive edges (23) of the dishware container (20),the peripheral seal extending circumferentially around the central pad, a shaping cavity (2) extending circumferentially between the central pad (1) and the peripheral seal (3), the shaping cavity (2) and the peripheral seal (3) being adapted to allow movement of the edges (23) during overmolding. Abstract figure: Figure 2,

Description

Title of the invention: MOLD AND METHOD FOR OVERMOLDING A DISHWARE CONTAINER FIELD OF THE INVENTION

[0001] The invention relates to the field of overmolding of tableware containers, in particular the overmolding of containers intended to contain food with a flexible material. STATE OF THE ART

[0002] In collective catering establishments, such as school and university canteens or establishments for the accommodation of the elderly, the use of dishes generates considerable noise due to the clashing of different crockery utensils. In addition to the inconvenience that this causes for the users of such establishments, the noise thus generated affects the health of the employees of these establishments, who are subjected to this noise for several hours a day in their workplace.

[0003] Indeed, studies have shown that the sound frequencies of impacts between tableware can reach high values ​​beyond 1.5 kHz which are detrimental to the comfort and health of human beings. Prolonged exposure to such sound frequencies thus poses a real public health problem.

[0004] In order to reduce noise due to these impacts, it is known to use tableware covered with a flexible material such as silicone. Two methods advantageously make it possible to manufacture bi-material tableware comprising silicone. Firstly, the tableware can be sprayed with a so-called RTV silicone (for room-temperature vulcanizing or silicone vulcanizing at room temperature). This method consists of spreading or spraying the malleable silicone, making it possible to cover the tableware, the crosslinking or hardening of the silicone advantageously taking place at room temperature. However, RTV silicone has a high viscosity even at room temperature, and is therefore not suitable for rapid and precise overmolding of the tableware.In particular, when the shape of the tableware is complex, the material takes a considerable amount of time to cover the tableware, and cannot precisely match its shape, and it may be necessary to post-process the tableware after overmolding to obtain the desired finished product. This generates material waste and therefore undesirable pollution and production costs. In addition, the time required for crosslinking of RTV silicone can be up to several days, making such processes unsuitable for industrial-scale tableware production.

[0005] Another process for manufacturing bi-material tableware is injection Liquid Silicone Rubber (LSR). This material has the advantage of exhibiting highly thixotropic properties, that is, when subjected to shear stresses - as is the case during injection under pressure into a mold - its viscosity decreases sharply and it exhibits a liquid state, allowing the material to spread quickly, adopting the shape imposed by the mold and the tableware. In addition, LSR silicone can crosslink much more quickly than RTV silicone, typically in less than a minute, and thus significantly reduce the time required for overmolding the tableware. This type of process is carried out in a mold made of a hard material, particularly steel, so as to ensure that the mold is not damaged during use, and tolerances between the mold and the fins of the container are avoided as much as possible.

[0006] However, for industrial-scale production, it is desirable to use tempered glass tableware, which is cheaper and much lighter than tableware made from materials such as ceramic or earthenware. Thermal tempering of the glass gives it a mechanical strength suitable for food use, but has the consequence of deforming the tableware, which in its tempered state has variations in diameter and height of up to several millimeters - that is to say, it is neither perfectly round nor perfectly flat, unlike porcelain or earthenware tableware.These dimensional variations make tempered glass tableware unsuitable for known injection overmolding processes, for example with LSR silicone: the tableware cracks or breaks due to the considerable pressure it is subjected to during injection - which can be up to around 700 bars - a pressure necessary to reduce the production cycle time of a tableware container as much as possible, the injection time required evolving inversely with the injection pressure. This pressure, and the associated reduction in injection time, are also necessary to prevent the silicone from crosslinking on contact with the mold, due to the high temperature of the latter. Statement of the invention

[0007] An objective of the present application is to propose a mold as well as a method for injection overmolding a tableware container which are adapted to tempered glass tableware and the dimensional irregularities which it presents, that is to say which allow overmolding of the tableware without cracking it.

[0008] Another objective of the present application is to allow a seal between the container and the mold which is satisfactory for the injection of LSR silicone, despite such irregularities in the size of the container.

[0009] Another objective of the present application is to provide a mold and a method allowing rapid and precise overmolding of dishes despite such dimensional irregularities.

[0010] Another objective of the present application is to propose a mold and a process suitable for industrial-scale production, allowing the production of silent tableware, in particular for use in collective catering establishments.

[0011] To this end, the invention relates, according to a first aspect, to a mold for injection overmolding a dish container with a material comprising silicone, the mold comprising a female part and a male part, the female part comprising: • an imprint configured to accommodate a first face of the dish container during overmolding, • an injection nozzle configured to allow the injection of the material comprising silicone into the impression on the first face,

[0012] the male part comprising: • a central stud formed from a material having a Shore D hardness of between 50 and 60 or comprising a coating of material having a Shore D hardness of between 50 and 60, configured to receive a second face of the dish container, • a peripheral seal formed from a material with Shore A hardness between 50 and 60, and configured to receive edges of the dish container, the peripheral seal extending circumferentially around the central stud, • a shaping cavity extending circumferentially between the central stud and the peripheral seal,

[0013] the shaping cavity and the peripheral seal being adapted to allow movement of the edges during overmolding.

[0014] Thus, the container is free to move sufficiently so as not to be subjected to stresses which would exceed its mechanical strength, while being supported so as to guarantee a distribution of the forces over its entire surface, thus avoiding excessively high local stresses, and presenting a seal with the mold sufficient for the injection of liquid silicone.

[0015] According to one embodiment, the mold comprises a vacuum pump connected to a central orifice opening into a central zone of the pad so as to retain the second face on the central pad by suction.

[0016] According to one embodiment, the mold comprises a vacuum drawing system opening into the female part opposite the first face or opposite the male part.

[0017] According to one embodiment, the peripheral seal and / or the central bead comprises a material having anti-adhesive properties, in particular polytetra fluoroethylene, or is / are coated with a coating comprising a material having anti-adhesive properties, in particular polytetrafluoroethylene.

[0018] According to one embodiment, the peripheral seal and / or the shaping cavity are adapted to allow a displacement of the edges of less than 3 millimeters, preferably between 1 and 3 millimeters, more preferably between 1 and 2 millimeters.

[0019] According to one embodiment, the mold comprises at least one ejector disposed in the female part imprint and capable of moving the container away from the imprint by pushing on the first face.

[0020] According to one embodiment, said at least one ejector extends over the entire circumference of the imprint.

[0021] The invention relates according to a second aspect to a method of overmolding a tableware container with a material comprising silicone, comprising the steps of: a. positioning the container in a mold according to any one of the preceding claims, a second face of the container being placed on the central pad and edges of the container being received on the peripheral seal, b. close the mold by bringing the female part opposite the male part so as to hold the container between the female part and the male part, c. injecting the material comprising silicone through the injection nozzle until the first face is covered with said material, d. open the mold and remove the container.

[0022] According to one implementation, the method further comprises a step of drawing a vacuum from the air disposed between the second face and the central pad by means of a vacuum pump connected to a central orifice opening into a central zone of the pad, so as to retain the second face of the container on the central pad.

[0023] According to one implementation, the method further comprises a step of vacuum drawing the air disposed between the first face and the impression by means of a vacuum drawing system so as to facilitate the injection of the material comprising silicone into the impression.

[0024] According to one implementation, the method comprises, before or during the step of opening the mold, a step of separation between the first face of the container and the female part, implemented by actuation of pushers arranged in the imprint of the female part.

[0025] According to one implementation of the method, the dishware container is a tempered glass container.

[0026] According to one implementation of the method, the container is a plate or a ramekin. DESCRIPTION OF FIGURES

[0027] Other characteristics, aims and advantages of the invention will emerge from the following description, which is purely illustrative and non-limiting, and which must be read in conjunction with the appended drawings in which:

[0028] - [Fig.l] schematically illustrates a dish container obtained by a process overmolding as proposed

[0029] - [Fig.2] schematically illustrates a mold as proposed;

[0030] - [Fig.3] schematically illustrates a process for overmolding a container of dishes as proposed. DETAILED DESCRIPTION OF THE INVENTION

[0031] According to a first aspect, the invention relates to an injection overmolding mold. With reference to [Fig.l], which represents a generic tableware container, such a container 20 comprises a first face 21 intended to rest on a table or a tray and a second face 22 receiving the food placed on or in the container. The container 20 further comprises edges 23, extending circumferentially around a central portion 24. The edges 23 may extend parallel to the central portion 24, for a flat plate, or have a more or less significant angle with this central portion 24. It is also possible for the central portion 24 and / or the edges 23 to be at least partly curvilinear, for example in the case of a bowl or a ramekin.

[0032] The mold 10 which is the subject of the invention is shown in [Fig. 2]. It comprises a male part 11 and a female part 12. The female part 12 is provided with an imprint 13 configured to receive, in use, the first face 21 of the dish container 20, while the male part 11 is provided with a central stud 1 configured to receive the second face 22 of the container 20.

[0033] A main axis X of the mold is defined as being an axis perpendicular to the planes formed on the one hand by the surface of the female part 12 on which the imprint 13 is arranged, and on the other hand by the surface of the male part 11 on which the stud 1 rests. The main axis X also passes through the respective centers of the imprint 13 and the stud 1. Said main axis also defines the opening-closing direction of the mold.

[0034] Naturally, the shapes of the imprint and the pad must be adapted to the geometry of the container 20 that it is desired to overmold. For this purpose, when it is necessary to overmold different container geometries, several separate molds 10 can be used.

[0035] The female part 12 comprises an injection nozzle 9 by means of which a material comprising silicone can be injected into the impression 13, in order to cover the first face 21 with said material. The nozzle 10 is preferably arranged in the middle of the imprint 13, but can be arranged in other positions allowing it to open into the imprint 13.

[0036] The central stud 1 of the male part 11 must be formed from a flexible material, and having a coefficient of friction sufficiently low to allow movement of the container 20. By flexible, we mean a material with a Shore D hardness of between 50 and 60. Alternatively, the central stud 1 can be formed from a harder material, but covered with a coating with a coefficient of friction sufficiently low to allow movement of the container 20, and having a Shore D hardness of between 50 and 60. Due to these mechanical properties, the surface of the central stud 1 can receive the second face 22 of the container 20 so as to allow movement of the container 20 perpendicular to the main axis X of the mold 10.Thus, the container 20 naturally takes the position in which the forces due to the injection pressure are distributed over its surface, and the risk of seeing locally concentrated forces develop which are likely to damage the container 20 is minimized.

[0037] The mold 10 is particularly suitable for overmolding containers 20 made of tempered glass, which have dimensional irregularities along the three axes, for the reasons cited above.

[0038] According to one embodiment, the central pad 1 comprises a material having non-stick properties, in particular polytetrafluoroethylene - known under the trademark Teflon®. The central pad 1 may also be made of another material covered with a non-stick coating.

[0039] On the surface of the male part 11 receiving the stud 1, a peripheral seal 3 extends in a circle centered on the main axis X, so as to be at a distance from the main axis X greater than that corresponding to the circumference of the stud 1. This peripheral seal has the function of serving as a support for the edges 23 of the dish container 20 when the latter is placed in the mold 10. Like the stud 1, the seal 3 is formed from a flexible material, the Shore A hardness of which is between 50 and 60. In a similar manner to the stud 1, the flexibility of the peripheral seal 3 allows a movement of the edges 23 of the container 20 during overmolding so as to ensure the best possible distribution of the forces on the surface of the container 20.

[0040] According to one embodiment, the peripheral seal 3 comprises a material having non-stick properties, in particular polytetrafluoroethylene - known under the trademark Teflon®. The peripheral seal 3 may also be made of another material covered with a non-stick coating. This characteristic has the advantage of preventing the edges 23 of the container from adhering to the peripheral seal 3, and therefore of facilitating the removal of the container 20 from the mold 10 after overmolding.

[0041] Between the pad 1 and the seal 3, the surface of the male part 11 forms a shaping cavity 2, that is to say that the part of the edges 23 of the container 20 located between the pad 1 and the peripheral seal 3 in a direction perpendicular to the main axis X does not rest directly on the male part 11, the shaping cavity 2 being located between this part of the edges 23 and the surface of the male part 11. The shaping cavity 2 thus contributes, jointly with the peripheral seal 3 and the pad 1, to allowing movement of the container 20 during overmolding.

[0042] The peripheral seal 3 and / or the shaping cavity 2 may be adapted to allow a displacement of the edges 23 of less than 3 millimeters, preferably between 1 and 3 millimeters, and even more preferably between 1 and 2 millimeters.

[0043] The mold 10 comprises a closing system capable of moving the male part 11 and the female part 12 relative to each other. The closing system may be capable of moving the male part 11 and / or the female part 12. The closing system may in particular comprise jacks, such as hydraulic or pneumatic jacks. The mold 10 may be a horizontal press mold, i.e. comprising jacks arranged horizontally, the surfaces of the male 11 and female 12 parts then extending along a vertical plane, or a vertical press mold with jacks arranged vertically, the surfaces of the male 11 and female 12 parts then extending along a horizontal plane.

[0044] The mold 10 may, according to a particular embodiment, comprise a vacuum pump 5 in order to retain the second face 22 of the container 20 on the central stud 1 by suction, once the plate is positioned in the mold 10. This vacuum pump 5 is particularly suitable when the mold 10 is of the horizontal press type, because the faces 21, 22 of the container are then arranged in a vertical plane once placed in the mold, and it is therefore necessary to ensure that the container 20 is pressed against the stud 1 when the mold 10 is not in the fully closed position. However, such a vacuum pump 5 can also be provided when the mold 10 is of the vertical press type.

[0045] The vacuum pump 5 is connected to an orifice 7 opening into the pad 1, preferably in the center thereof. When the vacuum pump 5 is placed at a distance from the pad 1, a conduit 6 may be provided to connect the pump 5 to the orifice 7.

[0046] Another embodiment provided for ensuring the plating of the second face 22 of the container on the central pad 1 comprises a support seal 15 arranged on the central pad. The support seal 15 is a circular seal, centered on the main axis X and arranged on the surface of the central pad 1. This seal has adhesive properties making it possible to ensure the maintenance of the second face 22 on the central pad 1, including when the mold 10 is of the horizontal press type.

[0047] It is possible to combine the two embodiments mentioned above and provide a central pad 1 comprising an orifice 7 connected to a vacuum pump 5, as well as a support seal 15.

[0048] The mold 10 may comprise a vacuum system 4. Such a system opens into the female part 12 either directly opposite the first face 21 of the container 20 when the latter is placed in the mold 10, or opposite the male part 11. The vacuum system 4 makes it possible to reduce the pressure of the air located between the container 20 and the female part 12, thus facilitating the injection of silicone through the nozzle 9.

[0049] When the lower face 21 of the container 20 has a large surface area, there is a risk that the injected material will not adhere only to the container 20, but also to the impression 13 or to the female part 12. The application of chemical substances or soapy water can make it possible to detach the injected material from the impression 13 or from the female part 12, however with mixed results. To this end, the invention comprises, according to one embodiment, one or more pushers 14 arranged in the cavity 13 and capable of moving the container 20 away from the cavity 13. This may be a plurality of pushers 14 or a single circular pusher, centered on the main axis X and extending over the entire circumference of the cavity 13. Thus, the need to use particular products to detach the material is eliminated, reducing the operating costs of the mold.Furthermore, this embodiment has the advantage of being easily automatable - it is sufficient to provide actuation of the pusher(s) 14 when it is necessary to separate the container 20 from the mold 10 - and is therefore suitable for use on an industrial scale.

[0050] The invention further relates to a method 100 for overmolding a dishware container 20 with a material comprising silicone, in a mold 10 as described previously. With reference to [Fig. 3], the method comprises, in its most general embodiment, a step 101 of positioning the container 20 in the mold 10, the second face 22 of the container 20 being placed on the central stud 1, the peripheral seal 3 receiving the edges 23 of the container 20. After positioning the container 20, a closing step 102 is implemented, according to which the female part 12 is brought opposite the male part 11 by actuating the closing system of the mold 10. The container is then retained between the male and female parts 11, 12 and does not move until the injection of material has started.This is followed by a step 105 of injecting the material comprising silicone, preferably a liquid silicone rubber, through the injection nozzle 9 arranged in the female part 12 so as to cover the entire first face 21 of the injected material. During the injection step, the container 20 will be free to adopt a position which reduces local forces, due to the particular characteristics of the mold 10 described above. Finally, a step 107 of opening the mold is implemented, allowing the removal of the . container 20 relative to mold 10.

[0051] Following the positioning step 101, it is not necessary for the edges 23 of the container 20 to reach, over the entire circumference thereof, the end of the peripheral seal 3 furthest from the main axis X. Due to the dimensional variability of the container, it is possible that the edges 23 do not reach the same position of the peripheral seal 3 over the entire circumference of the container 20. It will then be possible to inject a thicker layer of material at the circumferential positions where the container 20 has a reduced diameter, so as to obtain an overmolded container of substantially homogeneous diameter after implementation of the overmolding process 100.

[0052] The type of material injected through the injection nozzle 9 has a direct impact on the quality of the overmolded container 20 obtained. According to one embodiment, the material injected during the injection step 105 is a liquid silicone gum having self-adhesive properties. This ensures that a tableware container 20 is obtained having satisfactory molecular cohesion between the injected silicone and the material of which the container 20, before implementation of the overmolding method 100, is made.

[0053] According to one implementation of the method, when the male part 11 of the mold 10 comprises a vacuum pump 5, a vacuum drawing step 103 is carried out before the injection step 105 so as to retain the second face 22 of the container 20 on the central pad 1, either after closing 102 of the mold 10, or directly after positioning 101 of the container 20 on the central pad 1, in particular when the mold 10 is of the horizontal press type and the container 20 could not hold on the central pad 1 in the absence of a vacuum drawing.

[0054] According to another implementation of the method, when the female part 12 comprises a vacuum system 4, the method may comprise a step 104 of vacuuming the air disposed between the first face 21 and the cavity 13 by means of the vacuum system 4, so as to reduce as much as possible the pressure between the first face 21 and the cavity 13 and to facilitate the movement of the injected material, which covers the first surface 21. It is thus possible to reduce the time required for the injection step 105 and to avoid premature crosslinking of the injected material. The vacuum step 104 by the vacuum system 4 is carried out after the step 102 of closing the mold, and before or after a possible step 103 of vacuuming by the vacuum pump 5.

[0055] According to an implementation of the method, a step of separating 106 the first face 21 of the container 20 from the female part 12 is implemented either after the opening step 107, or possibly during the opening 107 of the mold 10. The separation 6 is achieved by actuating the pushers 14 arranged in the recess 13 of the female part 12.

Claims

Claims

1. Mold (10) for injection overmolding a dishware container (20) with a material comprising silicone, the mold (10) comprising a female part (12) and a male part (11), the female part (12) comprising: • an imprint (13) configured to accommodate a first face (21) of the dishware container during overmolding, • an injection nozzle (9) configured to allow the injection of the material comprising silicone into the imprint (13) on the first face (21), the male part comprising: • a central stud (1) formed from a material having a Shore D hardness of between 50 and 60 or comprising a coating of a material having a Shore D hardness of between 50 and 60, configured to receive a second face (22) of the dishware container, • a peripheral seal (3) formed from a material having a Shore A hardness of between 50 and 60,and configured to receive edges (23) of the dish container (20), the peripheral seal extending circumferentially around the central stud, • a shaping cavity (2) extending circumferentially between the central stud (1) and the peripheral seal (3), the shaping cavity (2) and the peripheral seal (3) being adapted to allow movement of the edges (23) during overmolding.,

2. Mold (10) according to the preceding claim, comprising a vacuum pump (5) connected to a central orifice (7) opening into a central zone of the pad (1) so as to retain the second face (22) on the central pad (1) by suction.

3. Mold (10) according to any one of the preceding claims, comprising a vacuum drawing system (4) opening into the female part (12) opposite the first face (21) or opposite the male part (11).

4. A mold (10) according to any preceding claim, the peripheral seal (3) and / or the central stud (1) comprising a material having non-stick properties, in particular polytetrafluoroethylene, or being covered with a coating comprising a material having non-stick properties, in particular polytetrafluoroethylene.

5. Mold (10) according to any one of the preceding claims, the peripheral seal (3) and / or the shaping cavity (2) being adapted to allow a displacement of the edges (23) of less than 3 millimeters, preferably between 1 and 3 millimeters, more preferably between 1 and 2 millimeters.

6. Mold (10) according to any one of the preceding claims, comprising at least one pusher (14) arranged in the imprint (13) of the female part (12) and capable of moving the container away from the imprint (13) by pushing on the first face (21).

7. Mold (10) according to the preceding claim, said at least one pusher (14) extending over the entire circumference of the imprint (13).

8. A method (100) of overmolding a dishware container (20) with a material comprising silicone, comprising the steps of: a. positioning (101) the container (20) in a mold (10) according to any one of the preceding claims, a second face (22) of the container being placed on the central stud (1) and edges (23) of the container being received on the peripheral seal (3), b. closing (102) the mold (10) by bringing the female part (12) opposite the male part (11) so as to retain the container (20) between the female part (12) and the male part (11) c. injecting (105) the material comprising silicone through the injection nozzle (9) until the first face (21) is covered with said material, d. opening (107) the mold (10) and removing the container (20) therefrom.

9. Overmolding method according to claim 8, further comprising a step of vacuum drawing (103) of the air disposed between the second face (22) and the central pad (1) by means of a vacuum pump (5) connected to a central orifice (7) opening into a central zone of the pad (1), so as to retain the second face (22) of the container on the central pad (1).

10. An overmolding method according to any one of claims 8 or 9, further comprising a step of vacuum drawing (104) of the air disposed between the first face (21) and the imprint (13) by means of a vacuum drawing system (4) so ​​as to facilitate the injection (105) of the material comprising silicone into the imprint (13).

11. Overmolding method according to any one of claims 8 to 10, comprising before or during the step of opening (107) the mold a step of separation (106) between the first face (21) of the container and the female part (12), implemented by actuation of pushers (14) arranged in the imprint (13) of the female part (12).

12. An overmolding method according to any one of claims 8 to 11, the tableware container (20) being a tempered glass container.

13. Overmolding method according to any one of claims 8 to 12, the container being a plate or a ramekin.

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