FR3022175A1 - SYSTEM FOR INJECTING AN ARTICLE WITH A MULTILAYER STRUCTURE - Google Patents

Abstract

A system for injecting a multilayered article comprises a nozzle with a generally tubular and concentric two-part nozzle body (100) (110, 120), the outer portion (120) having a common injection port . An obturator (200) is disposed in the body and comprises two shutter elements (210, 220) integral and arranged around each other. The first seat (124, 128) is formed adjacent the injection port (124) to cooperate with the inner closure member (210), and a second seat (112a) is formed in a terminal region of the inner body portion (110) for cooperating with the outer sealing member (220). An inner material supply channel (CA3) is formed between the two closure members (210, 220), an intermediate material supply channel (CA2) is formed between the outer sealing member (220) and the inner body portion (110), and an outer material supply channel (CA1) is formed between the two body portions (110, 120), and means (125, 115, 225; 127, 117). are provided for supplying the supply channels by allowing the shutter to move, the shutter is able to occupy selectively a raised position where the three supply channels (CA3, CA2, CA1) communicate with the orifice of injection, an intermediate position where only the inner supply channel (CA3) and the external supply channel (CA1) communicate with the injection port, and a lowered position where all the supply channels (CA3, CA2 , CA1) are isolated from the injection port.

Description

Field of the Invention The present invention generally relates to systems for injecting an article with a multilayer structure. STATE OF THE ART Injection systems are already known for injecting sandwich structure parts. An example of such a part is a preform with outer and inner layers and a functionalized middle layer, for example constituting an ultraviolet radiation barrier.

WO2011 / 006999 gives an example of such a system. However, in all known systems require two shutter members each having their mobility, with consequent construction and / or complex motion control arrangement.

SUMMARY OF THE INVENTION The object of the invention is to propose a system in which a mono-material injection or multi-component injection can be selectively made using a single movable shutter element, and a single associated displacement control means.

For this purpose, a system is proposed for injecting a multilayer structure article comprising an inner layer, an intermediate layer and an outer layer formed of materials that are brought distinctly to a common injection orifice, characterized in that it comprises an injection nozzle comprising: a nozzle body with an inner body portion and an outer body portion, generally tubular and concentric, the outer portion of the nozzle body defining the common injection port for the materials, a double shutter disposed within the inner body portion and comprising two mutually translational shutter members, a first member or inner member being disposed within a second outer member or member, of annular section, which denier ends in recess of the first element, a first seat being formed in the vicinity of the injection port to cooperate with a terminating part one of the inner closure member, while a second seat is formed in an end region of the inner body portion to cooperate with the outer sealing member, an inner material supply channel being formed between the two closure members, an intermediate material supply channel being formed between the outer sealing member and the inner body portion, and an outer material supplying channel being formed between the two body parts. , and means being provided for supplying the supply ducts with their respective materials while allowing the shutter to move, the shutter being able to selectively occupy: a raised position in which the shut-off elements are disengaged from their respective seats, the three supply channels thus being in communication with the injection orifice, an intermediate position in which the external sealing element r is in generally sealed contact with its seat, so that only the inner supply channel and the external supply channel are in communication with the injection orifice, and a lowered position in which the two elements of shutter are in sealing contact with their respective seats, so that all the supply channels are isolated from the injection port. Some preferred but non-limiting aspects of this system include the following features, taken individually or in any technically compatible combination: the inner and outer feed channels are fed with the same material. the injection port is annular and able to communicate with an annular inlet of a mold cavity. the seat for the outer closure member is a cylindrical portion of the end region of the inner body portion, the cross section of which is substantially the same in shape and dimension as the outer cross section of an inner portion of the external sealing element. the system comprises, in the vicinity of the injection orifice, a lamination chamber delimited by a generally frustoconical inner region of the outer nozzle body part, narrowing towards the injection orifice, an annular passage of controlled width permanently communicating the external supply channel with said chamber. said lamination chamber is formed in a tip secured to the outer body portion. The inner and outer feed channels are fed from a first feed channel formed in the outer body portion, directly communicating with the outer body portion. external supply duct and communicating with the inner supply channel via a second supply channel formed in the inner body portion and a third supply channel formed in the outer shutter portion, the second and third supply ducts. The power supply is configured to be in mutual communication regardless of the position of the shutter in the body. the intermediate feed channel is defined around a reduced section region of the outer shutter and communicates with a feed channel passing through the outer and inner body portions. According to the invention, an equipment for multi-cavity injection 30 is also proposed, characterized in that it comprises a plurality of systems as defined above, fed with materials by common feed means, and means for Shutter control controlled in a common way. BRIEF DESCRIPTION OF THE DRAWINGS Other aspects, objects and advantages of the present invention will become more apparent upon reading the following detailed description of a preferred embodiment thereof, given by way of non-limiting example and with reference in the accompanying drawings, in which: FIGS. 1A, 1B and 1C are views in axial section of a shut-off injection nozzle according to the invention, in three different shut-off positions, FIGS. 2A, 2B and 2C are partial enlarged views of FIGS. 1A, 1B and 1C, in the vicinity of the injection point, and FIG. 3A is an enlarged partial view of FIG. 2A. DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT It will be noted first of all that the indications of the "high", "low", "upper", "lower", etc. type. In the present description, it is to be understood that the orientation of the nozzle as shown in the figures, but that in practice the nozzle may take any other orientation. Referring to the figures, there is shown a nozzle for the sandwich injection of plastic parts, with three layers of potentially different materials, but most often in practice with two outer layers formed of the same injectable material (material A) and an intermediate layer formed of a different injectable material (material B). Typically, the material B is a material intended to ensure a particular function in the injected part, and in particular a barrier function (for example an ultraviolet radiation barrier), a mechanical reinforcement function, etc. The injection nozzle shown in the figures is typically part of a multi-cavity injection system, being attached to a so-called "hot block" part acting as a mechanical support and supply of the injection materials to each nozzles, in a manner known per se. This hot block also supports the shutter control means of each of the nozzles. The nozzle 10 comprises a nozzle body 100 formed of two parts 110, 120 respectively inner and outer, generally coaxial and assembled to each other by sliding fit and support shoulders in the upper part, a cap 130 internally threaded from mechanically lock everything. The good coaxiality between the parts 110, 120 is ensured for example by one or more intermediate enlargements 114 fitting into a cylindrical bore 121 formed in the outer part 120. The diameter of the inner part 110 of the nozzle body is such that With the exception of the zones provided with guide enlargements 114, the parts 110 and 120 define between them a first annular channel CA1 for supplying material. In order to ensure the continuity of this channel CA1 at the enlargements 114, the latter do not extend all around the part 110, but only cover discrete angular zones, preferably regularly distributed.

The outer part 120 of the nozzle body ends in the lower part in the figures (end injection point side) by a nozzle 122 assembled to the workpiece 120 preferably by screwing, with a portion 123 which protrudes from the workpiece 120, is of generally conical shape and forms at its free end an injection orifice 124, provided in a manner known to those skilled in the art of fitting allowing its good cooperation with the mold at the inlet of the respective molding cavity. The nozzle 122 internally defines a stratification chamber CS of the materials supplied, as will be seen below. In a manner known per se, the tip 122 is made of a metal alloy having mechanical properties and adapted thermal conduction, to maintain the injection point region at a suitable temperature. In this regard, the nozzle comprises, in a manner also known per se, heating means, typically by Joule effect, to maintain the injected materials in the appropriate temperature range. The outer portion 120 of the nozzle body has, radially oriented, a first channel 125 for feeding the first material (A) injection, and a second channel 127 for feeding the second material (B) of injection. The channel 125, which also communicates with a feed channel from the hot block, opens into the first annular channel CA1, and is extended by a channel 115 formed at its right in the inner body portion 110. The channel 127 of supply of the material B opens into the bore 121 at a widening 114 of the inner part, and communicates directly with a through channel 117, also radially oriented and formed in the inner portion 110 to the right channel 127. From In this way, the material B can not flow towards the annular channel CA1. The radial channel 117 passing through communicates with an annular supply channel for material B, extending downwardly from said channel 117 between a reduced diameter portion of the outer portion 220 of the shutter and the bore 111 formed in the inner portion 110 of the nozzle body. The inner part 110 of the nozzle body has a cylindrical inner bore 111 into which the channel 115 for feeding material A, as well as the channel 117 for feeding material B, open. The bore 111 extends with a constant cross section over the entire axial extent of the nozzle body, except for its injection point-side region (bottom in the figures), where the inner portion 110 of the nozzle body has a frustoconical narrowing 112 of shape and of well controlled dimensions. Thus, as best shown in FIG. 3A, this narrowing firstly has an outer terminal edge 112a situated at a controlled distance from the internal frustoconical surface 126 of the nozzle 122 belonging to the outer part 120 of the nozzle body, so that defining an annular passage of controlled width P1 between the parts 110 and 120, which passage communicates with the annular channel CA1 supplied with the injection material A via the radial channel 125 as described above, and opens into the peripheral part of the CS laminating chamber. This passage P1 will form, in the flow formed in said lamination chamber and injected by the nozzle, the skin layer formed of the material A. In addition, the narrowing 112 of the portion 110 of the nozzle body 100 defines a bore axial cylindrical 112b opening on the injection port 124 and whose diameter is precisely defined to form a seat in which can slide a shutter 200 that will now be described, to selectively shut off or not the low output of a channel annular supply CA2 as will be detailed below. The shutter 200 formed of two parts 210 and 220, respectively inner and outer, assembled to each other integrally in axial translation. The outer portion 220 of the shutter is of generally tubular shape, with an inner cylindrical bore 221 traversing here all its axial extent. This part has, in a region situated at the right of the channel 115 of the inner part 110 of the nozzle body, arrangements making it possible to put this channel 115 into communication with the inside of the bore 221 independently of the axial position of the shutter 200 in the bore 111 (in the range of axial displacement of said shutter). These arrangements comprise a through radial channel 225 formed in the portion 220 of the shutter, opening outwardly on an annular shrinkage 224 formed in the outer surface of the portion 220 and extending over a height, in the axial direction, so determined that whatever the position of the shutter (see Figures 1A, 1B and 1C describing its three stable positions), the communication between the arrival of the material A and the inside of the bore 221 is ensured.

Alternatively, the through channel 225 could be given an oblong shape in the axial direction. Furthermore, the lower region 222 of the outer shutter portion 220 has a reduced section so as to delimit with the inner portion 110 of the nozzle body CA2 supply channel.

At the end of the outer portion 220 of the shutter located injection point side, its bore 221 opens towards said injection point. This end is further adapted, as illustrated in FIGS. 2A, 2B and 2C, to cooperate, in a sealing relation to the injected material, with the cylindrical bore 112b of the inner body portion 110, the diameter outside of the portion 220 being equal to or very slightly less than the internal diameter of said bore 112b, to guide the inlet of the end of the portion 220 into the bore 112b, said end externally having a slight bevel 228 (see FIG. The inner part 210 of the shutter 200 is received centrally in the bore 221 of the part 220, the two parts being integral in rotation and in translation.This fastening can be achieved by press fitting, screwing, welding, etc. The shutter portion 210 comprises an upper region 211 through which it fits intimately in the upper region of the bore 221, and a lower region 212 of narrower diameter, thus defining between it and the bore 221 a third annular channel CA3 extending to the lower opening opening of said bore 221. The transition between the upper and lower regions 211, 212 of the portion 210 is located immediately above the radial channel 225 formed in the portion 220 for the supply of the material A, so that the CA3 channel is fed with said material.

At its lower end in the figures, the portion 210 of the shutter extends beyond the opening opening of the portion 220 and comprises a terminal sealing member 214 capable of penetrating, in a sealing relationship to the injected materials. in the injection port 124 formed in the nozzle. In practice, this closure is achieved by simply penetrating the element 214 into the orifice 124, possibly being completed by a support of frustoconical surfaces between a shoulder surrounding the element and a bevel 128 internally surrounding the orifice 124. The distance axial direction between this end closure element 214 and the end of the outer portion 220 of the shutter is determined accurately according to the axial distance between the injection port 124 and the upper edge of the bore 112b forming seat for the lower part of the outer part of shutter. The nozzle structure described above makes it possible to bring the material A into the annular channel CA1 defined between the two parts 110, 120 of the nozzle body, to bring the material B into the annular channel CA2 defined between the inner part 110 the nozzle body and the outer portion 220 of the shutter, and to bring the material A also in the annular channel CA3 defined between the outer and inner portions 220, 210 of the shutter.

The position of the shutter is controlled by an actuator, for example a pneumatic or hydraulic jack known per se (not shown), so that the shutter can selectively adopt one of the three positions illustrated in FIGS. 2A, 1B and 2B, and 1C and 2C respectively.

The operation and behavior of the nozzle as described above will now be described as a function of the position of the shutter. In FIGS. 1A and 2A, the shutter 200 is in the fully raised position, so that on the one hand the terminal shutter element 214 of the inner part of the shutter portion 210 is located at a distance from the injection port 124, and secondly the lower end of the outer shutter 220 is located away from the bore 112b. In this situation, the three material flows conveyed in the three annular channels CA1, CA2 and CA3 can reach the region of the injection orifice 124 and organize their stratification in this region, to form a tri-material output flow to the molding cavity.

In FIGS. 1B and 2B, the shutter has been lowered by its actuator to an intermediate position such that the lower end of the outer shutter portion 220 is sealingly engaged with the material injected into the shutter. bore 112b which forms its seat. In this way the flow of material B arriving via the annular channel CA2 is stopped, and the nozzle injects only material A continuing to reach it via the annular channels CA1 and CA3. Finally in FIGS. 1C and 2C, the shutter has been lowered as far as its actuator to its lowest position, where not only the lower end of the outer obturator portion 220 is shut-off in its seat. 112b, but the closing shutter member 214 of the inner shutter portion 210 closes the injection port. In this situation, the three material streams are blocked. The injection system can be decoupled from the molding cavities and the ejected parts, for a new cycle.

It is understood from the foregoing that by controlling the shutter actuator 200 to selectively adopt one of the three positions described, it is possible to selectively interrupt any flow of material, inject a sandwich flow of ABA materials, or inject only material A. By setting the shutter control according to the filling of the mold cavity, it is therefore possible to locate in the finished part an intermediate layer of material B, having the desired functionality only where this functionality is necessary, while other parts of the finished part will consist only of the material A. Of course, the present invention is not limited to the embodiment described and shown in the drawings, but the skilled person will know find many applications and many variations and modifications. In particular: it can be useful for making parts of extremely different sizes, including very large parts such as vats and barrels; it can involve a wide variety of injectable materials, including combinations of materials from recycling with other materials; the geometry of the nozzle, and, where appropriate, the feed pressures of the materials, may be adapted to vary the proportions of the materials A, B and C in the final part, and thus the relative thicknesses of the corresponding layers, with in particular the possibility of having an economic material B, representing the largest amount of material (typically up to 80% or more), and higher grade materials A and C, constituting hides; as stated, the nozzle may be used to bring a flow of three separate materials A, B, C and at the point of injection, and not the materials A, B, A; to do this, it will suffice to provide two separate feeds for the materials A and C, one in communication with the only annular channel CA1 and the other in communication with the annular channel CA3 without being connected to the annular channel CA1, c ' that is, practiced in a place where the two body parts 110 and 120 are in intimate contact; the nozzle may be adapted so that the injection of the layered materials is effected not by a single circular orifice, but according to an annular-shaped outlet, in particular to produce hollow or partially hollow revolution pieces having a triple layer A , B, A or A, B, C in its peripheral wall.

Claims (9)

REVENDICATIONS1. A system for injecting an article having a multilayer structure comprising an inner layer, an intermediate layer and an outer layer formed of materials fed distinctly to a common injection port, characterized in that it comprises an injection nozzle comprising a nozzle body (100) with an inner body portion (110) and an outer body portion (120), generally tubular and concentric, the outer portion (120) of the nozzle body defining the common injection port (124) for the materials, a shutter (200) disposed within the inner body portion (110) and comprising two shut-off members (210, 220) integral in translation, a first member (210) or inner member being disposed within a second element (220) or outer element, of annular section, the latter ending in withdrawal of the first element, a first seat (124, 128) being formed in the vicinity of the injection port (124) to cooperate with an end portion (214) of the inner closure member (210), while a second seat (112a) is formed in an end region of the inner body portion (110) for cooperate with the outer sealing element (220), an inner material supply channel (CA3) being formed between the two closure elements (210, 220), an intermediate material supply channel (CA2 ) being formed between the outer closure member (220) and the inner body portion (110), and an outer material supply channel (CA1) being formed between the two body portions (110, 120), and means (125, 115, 225; 127, 117) being provided for supplying the supply ducts with their respective materials while allowing the shutter to be displaced, the shutter being able to occupy selectively: a raised position in which the shut-off elements are disengaged from their position. respective seats, the three supply channels (CA3, CA2, CA1) thus being in communication with the injection port, an intermediate position in which the outer sealing element (220) is in generally sealing contact with its seat (112a), so that only the inner supply channel (CA3) and the external supply channel (CA1) are in communication with the injection port, and a lowered position in which the two elements of The closure is in sealing contact with their respective seats, so that all the supply channels (CA3, CA2, CA1) are isolated from the injection port. 2. System according to claim 1, wherein the inner (CA3) and outer (CA1) feed channels are fed with the same material. 3. System according to claim 1 or 2, wherein the injection port is annular and adapted to communicate with an annular inlet of a mold cavity. 4. System according to one of claims 1 to 3, wherein the seat for the outer sealing element (220) is a cylindrical portion (112a) of the end region of the inner body portion, the cross section of which is substantially the same shape and dimension as the outer cross section of an inner portion of the outer closure member (220). 5. System according to one of claims 1 to 4, comprising in the vicinity of the injection port (124) a lamination chamber (CS) delimited by a generally frustoconical inner region of the outer nozzle body portion, narrowing towards the injection port, a passageannulaire (P1) of controlled width permanently communicating with the external supply channel (CA1) with said chamber. The system of claim 5, wherein said lamination chamber is formed in a tip (122) integral with the outer body portion (120). 7. System according to one of claims 1 to 6, wherein the inner and outer feed channels (CA3, CA1) are fed from a first feed channel (125) formed in the outer body portion. (120), communicating directly with the external supply channel (CA1) and communicating with the inner supply channel (CA3) via a second supply channel (115) formed in the inner body portion (120) and a third supply channel (225) formed in the outer shutter portion (220), the second and third supply channels (115, 225) being configured to communicate with each other regardless of the position of the shutter ( 200) in the body (100). 8. System according to one of claims 1 to 7, wherein the intermediate supply channel (CA2) is defined around a region of reduced section (222) of the outer shutter (220) and communicates with a supply channel (127, 117) passing through the outer and inner body portions (120, 110). 9. Equipment for multi-cavity injection, characterized in that it comprises a plurality of systems according to one of claims 1 to 8, supplied with materials by common supply means, and control means of shutter ordered in a common way.