FR2924046A1 - Blow mold for e.g. shampoo storing and distributing container, has cooling channel with profile similar to that of cavity and located at constant distance from cavity, where channel is provided in high thermal conductivity cooling zone - Google Patents

Abstract

The mold has a cavity (22) delimiting a shape of an object to be molded, and cooling channels for evacuating the heat outside the mold. The cavity has cooling zones made of material presenting different thermal conductivities adapted to the thickness of the object that is cooled after molding. The cooling channel (60) is provided in one zone, whose thermal conductivity is greater than that of other zones. The channel (60) has a profile similar to that of the cavity and located at constant distance (d) from the cavity.

Description

APPLICATION FOR PATENT B07-1783 - JT / PG OA 07452

Société Anonyme known as L'OREAL Multi-material mold. Invention of: BETHUNE Alain ABERGEL Aline CHARMEAU Jean-Yves BEREAUX Yves

2 Multi-material mold. The present invention relates to the manufacture of parts made of synthetic material, and in particular hollow bodies.

More particularly, the present invention relates to the manufacture of bottles or containers obtained by blowing a synthetic material inside a manufacturing mold, and intended to contain and distribute cosmetic or care products, such as shampoo . "Cosmetic product" means a product as defined in Council Directive 93/35 / EEC of 14 June 1993. The manufacture of parts using a blow mold requires a thermal regulation of said mold. In this regard, it is generally provided cooling channels within which circulates a heat transfer fluid capable of taking the calories from the plastic and to evacuate to the outside. These cooling channels are generally of simple geometry since they are conventionally obtained by milling or machining. The distances between the cooling channels and the mold cavity are therefore variable and areas of the cavity may be particularly difficult to cool. By way of illustration, FIG. 1 partially shows in perspective a print 1 of a traditional mold intended for obtaining a container for packaging and dispensing a product, and associated with such a cooling channel 2 obtained by machining. conventional.

Thus, it is conceivable that with such channels, the cooling of the cavity is not homogeneous, which can generate defects. In order to overcome this drawback, the patent application FR 2,067,051 provides a casting mold made by sintering a metal powder to obtain curved cooling channels and along the molding surfaces.

3 Moreover, the cycle time for obtaining plastic parts is strongly related to the cooling of the thickest zones. For the containers or flasks, these areas are conventionally the collar and the closed end forming bottom.

It is then easily conceivable that to reduce the cost of manufacturing a hollow body or container, or more generally of parts made of plastic material, it is necessary to increase the cooling efficiency. However, too much cooling in areas of reduced thickness may cause defects, such as marbling surface defects, or deformations. Thus, it is essential to ensure differential cooling between the different parts of the mold according to the thickness of the object to be molded.

In this regard, it is possible to use for the parts of the mold delimiting the impression of the object materials having different thermal conductivities. For more details, reference may be made for example to documents GB-A-2 238 974, US 4, 206, 171 or FR 2 080 760.

However, even with such differential cooling, it remains difficult to significantly reduce the cycle time for the production of molded parts, in particular because of the intrinsic characteristics of the materials used. The present invention therefore aims to overcome this disadvantage. The invention is more particularly intended to provide a mold, in particular a blow mold, capable of allowing improved evacuation of calories in certain areas of the mold cavity.

Another object of the present invention is to provide a mold, in particular a blow mold, for a container for packaging and dispensing a product, and in particular a cosmetic product.

The subject of the invention is a mold, in particular a blow mold, provided with at least one impression delimiting the shape of an object to be molded in particular by blowing and with cooling channels to ensure an escape of calories to the outside. of the mold.

The cavity comprises cooling zones made of materials having different thermal conductivities adapted to the thickness of the object to be cooled after molding. At least one cooling channel formed in a cooling zone with a high thermal conductivity relative to one or more other zones has a profile similar to that of the cavity in said zone. The distance between said channel and between the cavity in the cooling zone considered is substantially constant. This arrangement is particularly advantageous insofar as the use of materials having different thermal conductivities combined with the existence of a cooling channel of profile similar to that of the cooling footprint and located at a constant distance from it. This makes it possible to obtain a uniform and important cooling in the zone considered.

Indeed, the Applicant has determined that with such a design the cooling time in the case of a container of the type intended to contain shampoo is reduced by 15 to 33% compared to a traditional mold. This reduces the cycle time for obtaining parts from 9 to 15%, which implies a relatively high productivity gain. Advantageously, the cooling zone or zones with high thermal conductivity of the cavity are produced by sintering. In one embodiment, the cooling channel in the high thermal conductivity cooling zone has an at least partly curved profile. Preferably, the distance between the wall of the cooling channel and the cavity is smaller than the diameter of said cooling channel. In one embodiment, the distance between the wall of the cooling channel and the cavity is between 1 mm and 8 mm, and preferably equal to 4 mm.

Advantageously, the impression delimits the shape of a container intended to be filled with a cosmetic product, in particular shampoo, and provided with a body having a closed end forming a bottom and an open opposite end forming a neck. The cooling zone of the cavity delimiting the neck and / or the bottom of the container may be made of a material having a high thermal conductivity, for example aluminum, copper, aluminum alloy or copper, for example copper and berylium alloy. The cooling zone of the cavity delimiting the body of the container may in turn be made of conventional steel. In one embodiment, the mold cavity is cut into three cooling zones. Of course, it is also possible to cut the mold into a different number of areas, for example in two or four.

The present invention will be better understood on reading the detailed description of an embodiment taken by way of non-limiting example and illustrated by the appended drawings, in which: FIG. 1 is a detailed perspective view of a mold according to the prior art, FIGS. 2 and 3 show front and side views of a container obtained by blow molding; FIG. 4 is a partial perspective view of the blow mold for obtaining FIG. 5 is an exploded perspective view of the mold of FIG. 4, and FIG. 6 is a detailed perspective view of the mold of FIGS. 4 and 5. Figures 2 and 3, a container for packaging and dispensing a product, designated by the general reference numeral 10 and shown in a supposed vertical position. I1 has a longitudinal axis X-X 'of symmetry. In the embodiment considered, the container 10 is intended for packaging and dispensing a cosmetic product, especially a shampoo. However, it is easy to see that it could also apply to the packaging and distribution of other types of products. The container 10 comprises a body 12 provided with a closed lower bottom end 14 and an upper end which has a neck 16 coinciding with the longitudinal axis X-X '. As is known per se, the neck 16 is separated from the peripheral wall of the body 12 by an annular shoulder 18. The neck 16 is intended to receive a plug or closure cap (not shown) snapping on the collar 16, or to fix by any other appropriate means.

The container 10 is obtained inside a blow mold as partially illustrated in FIGS. 4 and 5 and designated by the general reference numeral 20. The container 10 can be obtained by extrusion blow molding or blow molding. The container 10 is made of synthetic material, for example polyethylene (PE), polypropylene (PP) or polyethylene terephthalate (PET). In a manner known per se, the blow mold 20 comprises a fixed part and a part movable delimiting a cavity 22 of the container 10. In the figures, only the movable portion 24 of the mold 20 is visible. It comprises studs 26 adapted to cooperate with corresponding recesses of the fixed part to ensure precise positioning of the two parts against each other. The fixed part of the mold 20 partially delimiting the cavity 22 is similar to that of the mobile part 24.

The movable portion 24 is cut vertically in three zones 28 to 32 provided to obtain a differential cooling of the cavity 22. The various zones 28 to 32 of the mold are attached to an assembly plate 34 and fixed relative to each other by screwing.

The lower zone 28 and the upper zone 32 delimit respectively the portion of the cavity 22 forming the bottom 14 of the container, and the neck 16 and the shoulder 18 (FIGS. 2 and 3). The intermediate zone 30 forms the part of the cavity 22 relative to the body 12.

The zones 28, 32 are designed to have at least partly higher thermal conductivities than the material used for the zone 30. Indeed, the bottom 14, the neck 16 and the shoulder 18 of the container 10 has a thickness greater than that of the body 12.

In this regard, the zones 28, 32 each comprise an insert 36, 38 made for example of aluminum, copper, aluminum alloy or copper, for example copper alloy and berylium. The insert 36 is attached to the zone 32 by any appropriate means, for example by screws (not shown). The insert 38 is in turn held in position by an anvil 40. The use of such inserts 36, 38 provides a mold 20 for differential cooling of the object to be molded at low cost. The mobile part 24 of the mold 20 has cooling channels 42 to 46 extending vertically along the cavity 22 from the insert 36 to near the upper end of the zone 30 of the mold 20. The cooling channels 42 to 46, here three in number, are regularly spaced along the cavity 22 and disposed in the vicinity thereof. Pipes 48, 50 are provided at the lower zone 28 of the mold 20 respectively for the supply of heat transfer fluid cooling channels 42 and 44, 46. The conduits 48, 50 open at a side face of the mold to be connected to a heat transfer fluid supply circuit. It is also provided, at the intermediate zone 30, channels 52, 54 of the heat transfer fluid in communication with the cooling channels 42 and 44, 46. To ensure effective cooling of the portion of the cavity 22 of the mold which corresponds to the shoulder 18 and the neck 16 of the container, the insert 38 comprises a cooling channel 60 having a general profile similar to that of the cavity 22, as can be seen in FIG. Indeed, the insert 38 is made by sintering so as to obtain a curved shape along the contour of the cavity 22, and this, as close to it. The

The axial height or dimension of the cooling channel 60 is substantially equal to that of the neck 16 and the shoulder 18. The cooling channel 60 has a section adapted to maintain a turbulent flow along the latter, which increases cooling efficiency. In order to ensure a uniform heat evacuation in this zone, the radial distance d between the internal wall of the cooling channel 60 and the external wall of the cavity 22 is constant, and this, over the entire height of the part of the cavity. footprint 22 corresponding to the height of the neck 16 and shoulder 18. The cooling channel 60 is located radially adjacent the cavity 22. As an indication, for a container 12 of the type intended to contain shampoo, the distance between the wall of the cooling channel 60 and the cavity 22 is between 1 and 8 mm, and preferably equal to 4 mm. The cooling channel 60 may for example have a radial dimension greater than the above-mentioned distance, and of the order of 10 mm. Bridges of materials 62 to 68 are here represented between the cooling channel 60 and the cavity 22. For a container intended to contain from 150 ml to 500 ml of product, the cylindrical cooling channels conventionally used in the prior art have a diameter of 8 mm for a section of about 50 mm2. By keeping this section for the same volume of heat transfer fluid, the cooling channel 60, closer to the cavity 22 and for which the heat exchange surface with said cavity is increased, makes it possible to promote homogeneity and efficiency. cooling in the portion of the cavity 22 which corresponds to the shoulder 18 and the container neck 16. This also increases the quality of the parts obtained.

In the embodiment described only the zone 32 or portion of the mold for cooling the neck 16 and shoulder 18 of the container is provided with at least one such cooling channel 60. Indeed, this portion of the container 12 is the one with the largest thickness. However, it is readily conceivable that it would be possible, without departing from the scope of the invention, to also provide a similar cooling channel for the part of the mold for cooling the bottom 14, for example during an increase in thickness of this bottom.

The cooling ducts and the corresponding parts facing the cavity 22 extend at least in part at least in the month according to arcs of radially offset center of centers, but which, however, have the same radius of curvature. The neck 16 and the bottom 14 have a curved profile. However, they may also have rectilinear portions. In this case, the cooling channel or channels extend parallel to the outer wall of the cavity 22 in the areas considered. The use of a high thermal conductivity material and the design of a cooling channel of general profile similar to that of the cavity and located at a constant distance from it, can significantly reduce the cooling time of the plastic material in the area. Thanks to the invention, a significant reduction in the cycle time required to obtain the molded parts is thus obtained, which makes it possible to reduce their manufacturing cost.

Claims (10)

1-Mold especially blow molding provided with at least one cavity (22) delimiting the shape of a molding object and cooling channels (42 to 46, 60) to ensure a calorie evacuation outside the mold , characterized in that the cavity (22) has cooling zones (28 to 32) made of materials having different thermal conductivities adapted to the thickness of the object to be cooled after molding, and in that at least one cooling channel (60) formed in a cooling zone (32) having a high thermal conductivity relative to one or more other zones has a profile similar to that of the cavity (22) in said zone; distance between said channel and between the cavity (22) in the cooling zone considered being substantially constant. 2-mold according to claim 1, wherein the cooling zone or zones with high thermal conductivity of the cavity are produced by sintering. 3-mold according to claim 1 or 2, wherein the cooling channel (60) in the cooling zone with high thermal conductivity has a profile at least partially curved. 4-mold according to any one of the preceding claims, wherein the distance between the wall of the cooling channel (60) and the cavity (22) is smaller than the diameter of said cooling channel. A mold as claimed in any one of the preceding claims, wherein the distance between the wall of the cooling channel (60) and the cavity (22) is between 1 mm and 8 mm and is preferably 4 mm. . 6-mold according to any one of the preceding claims, wherein the footprint (22) defines the shape of a container (10) intended to be filled with a cosmetic product, especially shampoo, and provided with a body having a closed bottom end (14) and an open, open end forming a neck (16). 7-mold according to claim 6, wherein the cooling zone (28, 32) of the cavity defining the bottom (14) and / or the neck (16) of the container is made of a material having a high thermal conductivity. 8-mold according to claim 7, wherein the cooling zone (28, 32) of the footprint defining the neck and / or the bottom of the container is made of aluminum, copper, aluminum alloy or copper, for example copper alloy and berylium. 9-mold according to any one of claims 6 to 8, wherein the cooling zone (30) of the cavity defining the body (12) of the container is made of steel. 10-mold according to any one of the preceding claims, wherein the cavity (22) is cut into three cooling zones (28 to 32).