IMPROVEMENTS IN INJECTION MOULDS

Abstract: Injection-moulding half-mould comprising a base plate (1), a nozzle-carrying plate (2), a cavity-carrying plate (3), a hot runner (4) to which there are associated a plurality of resisitive elements (6) connected externally to a power supply source via at least an electric conductor (9, 19) lead connected to an appropriate external connector, in which the nozzle-carrying plate (2) can be removed from the hot runner (4) without any need for either said electric conductor lead (9, 19) or the connections of the latter to the resistive elements (6) to be disconnected.

Description: IMPROVEMENTS IN INJECTION MOULDS DESCRIPTION The present invention refers to the main component parts of an injection mould adapted to enable a plastic substance in its fluid, ie. molten state, usually just after the extrusion thereof, to be injected into appropriate cavities for forming related preforms; in particular, the present invention applies in a preferred manner to machines adapted for moulding at the same time a plurality of plastic articles, ie. the so-called "preforms", that are intended for subsequent processing by blow moulding into appropriate final containers, especially plastic bottles. Although reference will be made in the following description, mainly for reasons of greater descriptive convenience, to a machine for moulding preforms of plastic material, as this is used in combination with the preliminary steps of melting and extrusion of said plastic material, it will be appreciated that the present invention shall be understood as applying also to other kinds of uses or applications, as far as these fall within the scope of the appended claims. It is generally known in the art that, during the preform moulding operation, use is generally made of a moulding machine comprising a stationary half-mould, which is firmly joined to the structure of the same machine, and a moving half-mould, which preferably moves in a vertical direction and is selectively closable into an appropriate position against said stationary half-mould. In prior-art solutions, the stationary half-mould usually comprises a base plate 1, a nozzle-carrying plate 2, a cavity-carrying plate 3, at least a hot runner 4, a plurality of nozzles 5, a plurality of resistive elements 6 associated to said hot runner, and a plurality of resistive elements 7 associated to said nozzles 5. The nozzle-carrying plate 2 is in the shape of a U turned upside down, and is arranged in an intermediate position between said base plate and said cavity-carrying plate, as this is illustrated in Figures 1 and 2 which are views of said three different plates in assembled and separated positions thereof, respectively. The resistive elements 6 are connected to a respective power supply source (not shown) via a respective plurality of electric conductor leads 9; each one of them is furthermore inserted in a wall of said nozzle-carrying plate and passes therethrough for coming out on the outside thereof, where it is connected to a respective terminal clamp of an appropriate connector 14. The resistive elements 7 that are associated to the nozzles 5 in the nozzle-carrying plate 2, are in turn connected to a power supply source (not shown) via a respective plurality of electric conductor leads 1 1 connecting the respective resistive element to a respective terminal clamp comprised in the same connector 14 that already connects the above- described electric conductor leads 9. It is therefore obvious that each one of said electric conductor lead 1 1 is contained, as shown in the Figures, in the body of said nozzle-carrying plate 2. All this is anyway largely known to all those skilled in the art and is only reviewed here shortly in order to more effectively introduce the technical context which the present invention actually refers to. During the practical use of the mould, there are quite frequently occurring such operating conditions as to make it necessary for access to be gained most conveniently and easily, as well as with a maximum extent of freedom in intervening, to the hot runner or the nozzles. In the majority of the cases, these operating conditions are brought about by maintenance needs of the hot runner, eg. due to a failed heating element requiring replacement, or due to a nozzle having plugged up, or, more simply, due to the hot runner itself needing to be cleaned up and cleared of slag and scum depositing therein after a prolonged use. Shortly, in all those circumstances in which the nozzle-carrying plate 2 must be disassembled and separated from the hot runner, the need logically arises for all conductor leads 9 to be first disconnected from respective terminal clamps (not shown), in order to be able to disengage said nozzle-carrying plate 2 from the hot runner and then remove said plate 2. However, the disconnection of all the terminal clamps involved by such an operation is considerably time consuming, ie. requires a lot of time during which the whole plant must of course be kept at a standstill, ie. inoperative. Upon conclusion of the planned maintenance or similar intervention, the reverse operation must be then carried out to re-connect all said conductor leads to respective terminal clamps, and this obviously requires a further lot of time and, therefore, this puts a further downtime penalty on the whole plant. In other words, such operations of disconnecting and reconnecting the above cited conductor leads, which are inherently rather long and delicate to carry out, demand a considerable extension of the machine downtime and an equally considerable increase in the number of man-hours spent with respect to the time and man-hour requirements of the actual maintenance intervention, and such an extension is hardly compatible with the productivity requirements placed on such machines, which are designed and made for heavy-duty operation, ie. so as to be able to operate in a substantially continuous manner. Based on the above considerations, it is therefore a main purpose of the present invention to provide a type of stationary half-mould which is adapted to do away with the above described drawbacks, is capable of being easily implemented using readily available and, therefore, cost- effective materials and techniques, and is further easy, reliable and safe to use. Such an aim of the present invention, along with further features thereof, is reached in a type of mould that is made and operates as recited in the appended claims. The present invention may take the form of a preferred, although not sole embodiment such as the one that is described in detail and illustrated below by way of non-limiting example with reference to the accompanying drawings, in which: - Figure 3 is a vertical cross-sectional view of a half-mould according to the present invention, with the base plate, the nozzle-carrying plate and the cavity-carrying plate thereof in a mutually aligned arrangement, but separated from each other; - Figure 4 is the same view as the one appearing in Figure 3, but with said plates connected to each other in their operating state; - Figure 5 is a view of the base plate as seen from the A - A section of Figure 3; - Figure 6 is a view of the base plate as seen from the B - B section of Figure 4; - Figure 7 is a view of the nozzle -carrying plate as seen from the C - C section of Figure 3. Although reference will be made in the following description to a vertical-drive, vertically extending machine, in which the stationary half- mould has its cavities facing upwards, it will be appreciated that the present invention shall be understood as also applying to and being useful for any other kind of moulding machines, in particular also the so-called horizontal-drive ones, in which the moving half-mould moves with a horizontal motion. With reference to the above listed Figures 3 to 7, the component parts that are similar or correspond to the component parts illustrated in Figures 1 and 2 are indicated with the same reference numerals, for reasons of greater comprehension and comparative convenience. A half-mould adapted to be used to produce preforms of plastic material comprises, as usual, the afore mentioned three plates along with corresponding resistive elements 6 and 7, as well as the nozzles 5. Said base plate 1 is provided with a housing 15 that is open upwards and, therefore, given the type of example described here, towards said nozzle-carrying plate 2; said housing 15 is delimited outwardly by at least a kind of shoulder 16. Said base plate 1 is further provided, along an upper edge 20 of said shoulder 16 thereof, and therefore opening towards the respective nozzle- carrying plate, with a recess 21 passing through from said housing 15 inside said base plate, in which there is arranged said hot runner 4, to the outside of said base plate. Said half-mould further comprises, according to the present invention, a plurality of electric conductor leads 19, each one of which connects a respective resistive element 6 of said hot runner to a respective external terminal clamp connected to a power supply source (not shown) . These electric conductor leads 19 are partly housed in said recess 21 that enables them to be able to be removed from the base plate without any need for them to be disconnected from the hot runner, by simply lifting them out of said through-passing recess. The nozzle-carrying plate 2 is in turn provided with a plurality of electric conductor leads 22 connecting respective resistive elements 7 to an external power supply source (not shown). In an advantageous manner, in order to enable the nozzle-carrying plate 2 to be displaceable with respect to the base plate 1 , ie. removable therefrom, said electric conductor leads 22 are connected externally to an appropriate connector 23 arranged on an outer side of the same nozzle- carrying plate 2, as this is illustrated in Figures 4 and 5, in such a manner as to ensure that said connector is able to be readily coupled with a further connector 24 which the power-supply leads for the energization of said resistive elements 7 are connected to. Furthermore, it proves equally advantageous if the electric conductor leads 19 are connected externally to an appropriate respective connector 25 arranged on an outer side of the same base plate 1 , as this is illustrated in Figures 4, 5 and 7, in such a manner as to ensure that said connector 25 is able to be readily coupled with a further connector 26 which the power-supply leads for the energization of said resistive elements 6 associated to the hot runner 4 are connected to. A suitable improvement lies in providing in the nozzle-carrying plate 2 a through-slot 27 having at least a side thereof opening outwardly, preferably upwards as shown in Figures 3, 4 and 7, in which the electric conductor leads 22 may be inserted throughout the distance covered by them from the resistive elements 7 and said connector 23. The provision of such a through-slot enables in fact the connector 23, the related electric conductor leads 22 and the respective resistive elements 7 to be pulled out with a single operation, without any need arising for all said component parts to be disconnected from each other. The operating modalities and the advantages of the present invention will at this point be apparent to all those skilled in the art. In fact, whenever a circumstance occurs or a need whatsoever arises, owing to which access has to be gained to the hot runner 4 or the nozzles 5, it will be sufficient for the three afore mentioned plates to be mechanically separated from each other, as illustrated in Figure 3, in order to readily gain free access to said hot runner or nozzles, without it being necessary for individually disconnecting said electric conductor leads 19 and 22 from and, when re-assembling, individually re-connecting said electric conductor leads 19 and 22 to the respective terminal clamps of the respective resistive elements 6 and 7. It will be also appreciated how, with this solution making use of distinct connectors 23 and 25 arranged on the outer surface of the base plate 1 and the nozzle-carrying plate 2, respectively, the possibility is also given for the nozzle-carrying plate to be most easily and quickly removed and replaced with a nozzle-carrying plate having different characteristics, as far as the latter is of course provided with the same kind of mechanical and electric interface elements. In full accordance with the aims of the present invention, a half-mould has in this way therefore been implemented, which enables the operating flexibility and productivity of the whole plant to be significantly boosted and the machine downtime to be considerably reduced along with the working time required to both replace the nozzle-carrying plates and carry out any required maintenance work on the hot runner and the associated functional parts.

Claims: CLAIMS 1. Injection half-mould comprising: - a base plate ( 1), - a nozzle-carrying plate (2), - a cavity-carrying plate (3), - at least a hot runner (4), - a plurality of nozzles (5) arranged in said nozzle-carrying plate (2), - a plurality of resistive elements (6) associated to said hot runner and connected externally to a respective power supply source via a respective plurality of electric conductor leads (9, 19) connected to appropriate external connector means, characterized in that said nozzle-carrying plate is adapted to be removed and displaced away from said hot runner without any need arising for said electric conductor leads (9, 19) or the connections between these leads and said resistive elements (6) to be disconnected, ie. separated. 2. Half-mould according to claim 1 , characterized in that - said hot runner (4) is contained in a proper housing ( 15) provided in said base plate ( 1), in which said housing is capable of being closed by said nozzle-carrying plate (2), - said housing ( 15) is delimited by at least a shoulder ( 16), which is provided, in correspondence of the side (20) facing said nozzle-carrying plate, with a recess (21) adapted to house said electric conductor leads (19) passing from the interior of said recess (15) to a zone on the outside of said base plate. 3. Half-mould according to claim 2, characterized in that said electric conductor leads ( 19) are connected externally to appropriate external connector means (25). 4. Half-mould according to claim 3, characterized in that said external connector means (25) is applied on to the outer surface of said base plate. 5. Half-mould according to claim 4, and further provided with a plurality of resistive elements (7) associated to said nozzles (5) and contained in said nozzle-carrying plate (2), as well as connected in turn to a power supply source via a respective plurality of electric conductor leads (22), characterized in that at least a portion of said electric conductor leads (22) is contained in the body of said nozzle-carrying plate, from which it comes then out on the outside thereof to be connected to a respective terminal clamp of at least a power-supply connector means (23). 6. Half- mould according to claim 5, characterized in that said power- supply connector means (23) is applied on to the outer surface of said nozzle-carrying plate. 7. Half- mould according to claim 6, characterized in that in the nozzle-carrying plate (2) there is provided a through-slot (27) that has at least a side thereof opening towards either said cavity-carrying plate or said nozzle-carrying plate, and is adapted to hose the portion of said electric conductor leads (22) that extends from said respective resistive elements (7) to said respective connector means (23).

Inventors: ROSSI MASSIMO, ROSSI, MASSIMO
Applicants: ROSSI MASSIMO, SIPA SPA, ROSSI, MASSIMO, SIPA S.P.A.
Application year: 2000
Main classification: B29C45
IPC codes: B29C45