FR2964060A1 - MULTI-STAGE ROTARY MOLD FOR INJECTION-BLOWING AND MULTI-INJECTION - Google Patents

Abstract

This mold, associated with a rotation system (4) or having an integrated rotation system, comprises: a fixed part (5), located at one end; an axially movable part (6), opposite to the fixed part; between the fixed part (5) and the mobile part (6), at least two rotatable parts (7, 8), coaxial and axially movable; at least one central plate (9) or non-rotating intermediate disposed between the rotating parts (7, 8). These various parts are provided with moldings (14, 26), fed by means of distribution (18) of material. The rotating parts (7, 8) are connected directly or indirectly to the rotation system (4). This is in particular a two-stage mold for injection blow molding or for multi-injection.

Description

The present invention relates to the field of plastics and, more particularly, to injection-blow molding and multi-injection techniques. It relates, more particularly, to a rotary mold for injection-blow molding or multi-injection, this mold being multi-stage and in particular bi-stage.

The invention is explained below by considering a mold for injection-blowing, without resulting in a limiting character. In the field of plastics, some hollow bodies, especially for the packaging of various products, such as yoghurt pots, pill dispensers for pharmaceutical products or tubes for cosmetics, are produced by an injection-blow molding technique. called "in hot cycle". This technique consists of injection molding a blank or preform of the hollow part in a first workstation, then transferring the blank or preform, while its material is not yet completely cooled but remains in the pasty state, to a second workstation where the blowing operation is carried out, which aims to give it its final form. French Patent Application No. 10.51272 filed February 23, 2010 in the name of the Applicant discloses such a hollow body molding process, and a tool for the implementation of this method, in which the blank or preform, still in use pasty state is transferred in rotation between the first injection molding station and the second blowing station. The tool may also include a third station dedicated to the ejection of the finished parts, a new rotation bringing said parts of the blowing station to the latter station. Thus, the various workstations are organized around a single mold, which has a rotating part to which is associated a rotation system. The approach described in this previous patent application already leads to a rationalization of the injection-blowing, for a complete realization of hollow bodies on a single machine, and in a single mold provided with a rotating part.

However, for reasons of productivity, it appears necessary to provide a maximum number of impressions for a machine and a mold, while the machines currently dedicated to injection-blowing allow impressions whose number is in some cases insufficient. The object of the present invention is to overcome this limitation, and so it aims to increase the number of molding cavities, for injection-blowing but also multi-injection applications, without increasing the power of the injection molding machine. 'injection. For this purpose, the subject of the invention is a multi-stage rotary mold for injection-blow molding and multi-injection, the mold being intended to be used on an injection molding machine equipped with a rotation system, preferably along an axis horizontal rotation, or this mold itself having an integrated rotation system, the mold being essentially characterized in that it comprises, in combination: - a fixed part, located at one end of the mold, - an axially movable part , non-rotating, opposite the fixed part, - between the fixed part and the axially movable part, at least two coaxial rotatable and axially movable parts, - at least one non-rotating central or intermediate plate, 15 disposed between the rotary parts, - molding cavities provided on the at least two rotating parts, as well as on the fixed and movable parts and on the or each central or intermediate plate, - distribution means of material to the moldings, in at least one angular position, for injection and / or blowing, the rotating parts being connected, directly or indirectly, to the rotation system. In particular, the rotatable mold object of the invention can be designed as a two-stage mold, with two coaxial rotating parts provided with molding cavities and with a single non-rotating central plate disposed between the two rotating parts, in which case preferably: - a first rotating part is directly linked to the rotation system, - the other rotating part is rotatably connected to the first rotary part by driving columns, which pass through an opening of the central plate, - The central plate is maintained at substantially equal distance from the fixed portion and the movable portion of the mold by mechanical means.

Thus, the mold of the present invention makes it possible to double or increase the number of molding impressions even more, while retaining the same power of the injection molding machine and, in particular, without it being necessary to increase the closing force of the mold, and also without increasing the footprint. The rotational drive of the rotary parts, of which there are at least two, is given by the rotation system which may be a rotating mechanical mold base, as described in French Patent No. 2775152 in the name of the Applicant. This rotation system here directly leads to a first rotating part, which itself rotates the other part or parts in a perfectly synchronized manner. Thus, the molding impressions of the various rotating parts are brought successively to the stations distributed at the periphery of these rotating parts. Insofar as these are stations where a supply of material to be molded or blown is necessary, the material distribution means can also be placed at the periphery of the rotating parts, appearing as at least one block of radially movable material distribution mounted radially on the fixed portion of the mold, actuating means of the jack type being provided for radially moving said material distribution block, in particular to bring the block closer to the rotating parts of the mold in the closed position of this mold, and to separate said block for the opening of the mold. During this opening of the mold, the rotating parts of which there are at least two must be separated from the fixed and mobile end portions of the mold, as well as from its central plate, if only so as not to be impeded in their rotation. This clearance of the rotating parts, bringing them in the middle of the spaces released on either side of the central plate, or intermediate plates, is obtained by the opening movement of the mold and by specific opening stops. The peripherally disposed distribution block, which carries the injection points applied against the mold parts in the closed position of the mold, can be directly supplied with molding material by an injection unit arranged perpendicularly to the direction of injection. opening / closing the mold, which however is a fairly expensive solution. In a variant of lower cost, the peripheral dispensing block is fed with material to be molded from an injection unit located in the axis of rotation of the rotating parts of the mold, and via minus one hot channel leading to the injection points carried by the distribution block. The design of a conventional injection molding machine is thus preserved, with an injection unit arranged horizontally in the opening / closing direction of the mold.

In any case, the invention will be better understood with the aid of the description which follows, with reference to the appended schematic drawing showing, by way of examples, a few embodiments of this multistage rotary mold: FIG. in section of a two-stage rotary mold according to the present invention, shown in the open position and mounted between two plates of an injection molding machine. Figure 2 is a sectional view similar to Figure 1, but showing this two-stage rotary mold in the closed position; Figure 3 is a front view of a rotatable portion of the mold of Figures 1 and 2, with an indication of the associated stations; FIGS. 4 and 5 are partial views of this mold, respectively in two successive positions, illustrating the ejection operation carried out in the "closed mold" position; Figures 6 and 7 are sectional views, respectively in two distinct positions, of a variant of the two-stage rotary mold according to the invention. The invention is described below, with reference to the drawing, in the case of its application to a two-stage mold for injection blow molding. The mold is, in use, placed on an injection molding machine which comprises a fixed plate 2 and a movable plate 3, which can be moved towards or away from the fixed plate 2 in a horizontal movement. On the movable plate 3 is mounted a rotation system 4, which is in particular a rotating mechanical mold base as described in French Patent No. 2725152. The rotation system 4 is designed to describe, to rotating parts (like specified below), a rotation about a horizontal axis A and a translational movement along the horizontal axis A. The mold itself is disposed, in use, between the fixed plate 2 of the press injecting and the rotation system 4. This mold comprises, inter alia, a fixed portion of mold 5 mounted on the fixed plate 2 of the injection molding machine, and a movable mold part 6 mounted on the rotation system 4. 35 Between the fixed part 5 and the moving part 6 of the mold are arranged two rotating mold parts, respectively 7 and 8, rotatably mounted about the horizontal axis A and also movable in translation along this horizontal axis A. The mold further comprises a plate Central 9, disposed between the two rotary parts 7 and 8. The first rotary part 7, situated on the side of the rotation system 4, is directly mounted on a central shaft 10 of this rotation system 4, able to be driven in rotation and in translation according to the horizontal axis A. The other rotating part 8, located on the side of the fixed part 5, is carried by a shaft 11 free to move in rotation and in translation relative to said fixed part 5. This other rotary part 8 is linked in rotation to the first rotary part 7 by drive columns 12, for example three in number, which extend parallel to the horizontal axis A and which freely pass through a wide opening 13 formed in the central plate 9. This non-rotating central plate 9 is kept at an equal distance from the fixed part 5 and the mobile part 6 of the mold by unrepresented mechanical means arranged outside the mold parts described in FIG. squ'ici here, and carried by the mold. The two rotating parts 7 and 8 of the mold comprise one and the other of the moldings 14, so as to constitute a two-stage rotary mold. More particularly, the mold is here designed as a mold for the production of hollow bodies by a "hot cycle" injection-blow molding technique; thus, the different molding cavities 14 are successively supplied, by the rotation of the rotating parts 7 and 8, to a molding station 15 by injection of blanks or preforms of the hollow bodies to be produced, and then to a blowing station 16 in which these hollow bodies receive their final form, an ejection station 17 is also provided (see Figure 3). It will be noted that the term "impression" here designates either a hollow molding part, or a relief molding part also designated as "core" and having the additional function of retaining the preform or preform on the rotating part during the rotation. of the latter, for the transfer of the blank or preform from one post to the next. In order to supply molding impressions 14 with molding material, a distribution block 18 of this material, mounted vertically on the fixed part 5 of the mold, is provided at the level of the injection molding station 15. being provided to move the distribution block 18 vertically. This distribution block 18 carries an injection nozzle provided with two injection points 21 and 22 provided for supplying respectively the molding cavities 14 of the two rotary parts 7 and 8. first rotary connector 23, placed at the rear of the shaft 10 of the rotation system 4, makes it possible to feed the first rotary part 7 with thermal regulation fluid, in particular in the region of the molding cavities 14 of this rotating part 7. A second rotary connection 24, placed at the rear of the shaft 11, makes it possible to feed the other rotating part 8 with thermal regulation fluid, in particular in the region of the fingerprints of molding 14 of this rotating part 8.

With regard to the axial movements, along the horizontal axis A, the mold is switchable between the open position shown in FIG. 1 and the closed position shown in FIG. 2. The displacement of the moving plate 3 of the injection molding machine prints directly to the movable part 6 of the mold its axial opening or closing movement. This axial movement is transmitted to the central plate 9 by the mechanical means mentioned above. It is also communicated to the two rotary parts 7 and 8, in particular by opening stops 25 (see FIG. 1, bottom). With regard to the rotating parts 7 and 8, the rotational movement about the horizontal axis A, allowed in the open position of the mold, is directly given to the first rotary part 7 by the rotation system 4 and its shaft 10. The rotation of the other rotating part 8 is given indirectly, from that of the first rotary part 7, via the driving columns 12. The rotations of the two rotary parts 7 and 8 are thus synchronized.

When the mold is brought into the closed position (FIG. 2), the distribution block 18 is lowered by a control of the hydraulic jack 19, to apply the two injection points 21 and 22 of the injection nozzle 20 to the periphery of the different parts, then tightened, of the mold. Conversely, the distribution block 18 makes an upward movement to clear the injection points 21 and 22, before opening the mold (see Figure 1). The high position of the distribution block 18 is maintained during the rotation of the rotating parts 7 and 8. Thus, considering by way of example the three-station design, as illustrated by FIG. 3, the operation of the mold is the Next: At the injection molding station 15, the mold being in the closed position, the material is injected by the distribution block 18 into the molding cavities 14 of the two rotating parts 7 and 8, as well as in other molding cavities 26 carried by the fixed part 5, the movable part 6 and the central plate 9 of the mold, at their periphery. The blanks or preforms 27 are thus molded.

At the same time, the blanks or preforms already reached at the blowing station 16 provided with the arrival of compressed air 28 are cooled and blown at this station, so as to obtain the final shape of the parts to be produced. Also simultaneously, at the ejection station 17, the finished parts 29 are ejected by means of an ejection plate 30.

At the opening of the mold, obtained by displacement of the moving plate 3 of the injection molding machine, the two rotary parts 7 and 8 are disengaged and are placed in the middle of the free spaces located on either side of the central plate 9. The rotation system 4 is then actuated to drive in rotation the first rotary part 7, which via the driving columns 12 also rotates the other rotary part 8. The two rotating parts 7 and 8 carry with them the blanks or preforms 27, held by the cavities 14, to transfer them from the injection station 15 to the blowing station 16. At the same time, these two rotary parts 7 and 8 carry with them the finished parts 29, from the blowing station 16 to the blast station. ejection station 17. After rotating one-third turn (120 °) of the two rotating parts 7 and 8, the movable plate 3 of the injection molding machine is moved in the opposite direction of its opening stroke, to close the mold . The central plate 9 of the mold then performs half of the stroke of the movable plate 3, and at the end of the closing movement: the first rotary part 7 is found positioned between the movable part 6 and the central plate 9, and - L ' another rotating part 8 is located between the fixed part 5 and the central plate 9.

With the mold thus closed, the distribution block 18 is again lowered and the same cycle is repeated, and so on. This produces hollow bodies by injection-blowing, with productivity doubled given the doubling of the number of cavities (in comparison with a mold with a unique rotating part).

FIGS. 6 and 7, on which the elements previously described are designated by the same reference numerals, illustrate an alternative relating to the feeding of the molding material to the molding cavities 14 and 26. This variant concerns an injection molding machine in which in a conventional manner, the injection unit is located horizontally along the axis A, as symbolized by an arrow F, while the injection points 21 and 22 are, as before, carried by a distribution block 18 to peripheral disposition, mounted movable in the vertical direction. In such a case, to feed the impressions with molten plastic material under pressure, it is intended to transfer this material through a hot channel 31, radially oriented, which extends into the fixed part 5 of the mold, between the injection unit (arrow F) and an inlet nozzle 32 of the distribution block 18. The hot channel 31 is extended by another axial direction hot channel 33, placed inside the distribution block 18 and extending itself by hot channels 34 and 35 respectively leading to injection points 21 and 22.

Figure 6 shows the assembly with the distribution block 18 in the raised and released position, the inlet nozzle 32 then being closed. FIG. 7 shows the same assembly with the distribution block 18 lowered and resting on the parts of the mold to be fed, the inlet nozzle 32 thus ensuring continuity between the hot channels 31 and 33.

As it is understood, this design can be modified by locating the injection points 21 and 22 not on the top of the mold but on the side thereof, the front side ("operator" side) or the rear side ( opposed to the operator), the hot channel 31 taking in this case a horizontal orientation.

Variations in the number of positions are possible, without changing the general configuration of the rotary mold and the injection molding machine. Thus, a first variant is to provide only two positions, separated by a rotation of 180 °, namely: - An injection station of the blank or preform, and - A blow and ejection station, the ejection of the finished part being done with the open mold, after the cooling of this piece. Another variant provides four stations, separated by rotations of 90 °, which are: - an injection station of the preform or preform, - a station for pre-blowing and / or recalibration of the preform temperature, - A final blowing station and cooling, and - An ejection station of the finished parts, the ejection taking place with the mold closed. Of course, other combinations are also possible. The injection molding machine is very easily adaptable to the number of mold stations, by the numerical programming of the rotation system 4. As a result, different molds, with variable number of positions (two, three or four positions), can be used on the same injection press. According to yet another variant, the rotary mold of the invention is designed as a mold for multi-injection, that is to say that the molding cavities of the rotating parts 7 and 8 of the mold are brought successively, by the rotation of these parts, to an injection molding station of a first material, and then to at least one injection molding station of another material, for example to perform an overmolding. In this variant of application also, the multiplication of the rotating parts increases the productivity of the mold, without increasing the closing force of the injection molding machine or its footprint, resulting in a gain in investment and energy consumption. . Note that, since separate materials must be injected at at least two molding stations, the distribution blocks for the different materials to be injected may be located not only in the upper part, above the mold, but also on one side or both sides of the mold.

It goes without saying, and as it follows from the foregoing, the invention is not limited to the embodiments of this rotary mold which have been described above, as examples; it embraces, on the contrary, all variants of implementation and application respecting the same principle. Thus, in particular, it would not deviate from the scope of the invention: - By multiplying the rotating parts, for example by providing three or four rotating parts, so as to obtain a multi-stage mold, the central plate is then replaced by at least two intermediate plates, this of course with an injection molding machine whose size between trays is appropriate; - By foreseeing more or fewer positions; - By replacing the rotation system, installed on the injection molding machine, with a rotation system integrated into the mold and creating the same rotational and axial movements; - Replacing or supplementing the supply of molding material, located at the periphery of the mold and in the upper part, by a side material supply, for example with a horizontally movable distribution block, or by a material inlet parallel to the axis of the mold.

Claims (9)

REVENDICATIONS1. Multi-stage rotary mold for injection-blow molding and multi-injection, the mold being intended to be used on an injection molding machine equipped with a rotation system (4), preferably along a horizontal axis of rotation (A), or this mold itself having an integrated rotation system, characterized in that it comprises, in combination: - a fixed part (5), located at one end of the mold, - an axially movable part (6), non-rotating, in contrast to the fixed part (5), - between the fixed part (5) and the axially movable part (6), at least two coaxial and axially movable rotating parts (7, 8), - at least one central plate (9) or non-rotating intermediate, arranged between the rotating parts (7, 8), moldings (14, 26) provided on the at least two rotating parts (7, 8), as well as on the fixed parts. (5) and movable (6) and on the or each central plate (9) or intermediate, - distribution means (18 to 22) of material to the moldings (14, 26) in at least one angular position for injection and / or blowing, the rotating parts (7, 8) being directly or indirectly connected to the rotation system. (4). 25 Rotary mold according to Claim 1, characterized in that it is designed as a two-stage mold, with two coaxial rotating parts (7, 8) provided with molding cavities (14) and with a central plate (9). ) non-rotating single disposed between the two rotating parts (7, 8). 30 Three-stage rotary mold according to Claim 2, characterized in that: - A first rotary part (7) is directly connected to the rotation system (4), - The other rotary part (8) is connected in rotation to the first rotary part (7) by driving columns (12), which pass through an opening (13) of the central plate (9), - This central plate (9) is kept substantially equal distance from the fixed part (5) and the movable part (6) of the mold by mechanical means. 4. Rotary mold according to any one of claims 1 to 3, characterized in that the rotation system (4) from which the rotating parts (7, 8) are driven, is a rotating mechanical mold base. 5. Rotary mold according to any one of claims 1 to 4, characterized in that the material distribution means, placed at the periphery of the rotating parts (7, 8), are in the form of at least one distribution block (18). ) of material mounted in a radial direction on the fixed part (5) of the mold, actuating means of the jack type (19) being provided for radially moving said distribution block (18) of material, in particular to bring this block closer together rotating parts (7, 8) of the mold in the closed position of the mold, and to separate said block for opening the mold. 6. Rotary mold according to claim 5, characterized in that the distribution block (18), at peripheral disposition, is supplied with material to be molded from an injection unit (F) located in the axis of rotation (A). rotating parts (7, 8) of the mold, and via at least one hot channel (31, 33, 34, 35) leading to the injection points (21, 22) carried by the distribution block ( 18). Rotary mold according to any one of claims 1 to 6, characterized in that opening stops (25) are provided to bring about, when the mold is opened, the rotating parts (7, 8) in the middle of the spaces released on either side of the central plate (9) or intermediate plates. 8. Rotary mold according to any one of claims 1 to 7, characterized in that it is designed as a mold for injection-blow molding "in a hot cycle", the molding cavities (14) of the rotating parts (7, 8 ) of this mold being successively supplied, by the rotation of these parts, to an injection molding station (15) of blanks or preforms, then to a blowing station (16). 9. Rotary mold according to any one of claims 1 to 7, characterized in that it is designed as a mold for multi-injection, the molding cavities (14) of the rotating parts (7, 8) of this mold being successively fed, by the rotation of these parts, to an injection molding station of a first material, then to at least one injection molding station of another material.