MOLD HOLDER FOR MOLDS FOR MANUFACTURING BOOTS OR THE LIKE MADE OF PLASTICS

Abstract: A mold holder for molds for manufacturing boots or the like made of plastics, which comprises a footing (10) for supporting a mold (11), with an upper closure cover articulated to the footing (10) and with a front door (14) for soles which is rotatable about an axis (15) which is longitudinal with respect to the mold. The door (14) is composed of a transverse frame (17) which is supported by the footing (10), is rotatable about the longitudinal axis (15) and is arranged below the surface that supports the mold. The frame (17) supports at least one sole support (22) which is pivoted so as to rotate about a corresponding axis (21) which lies outside the front dimensions of the mold (11).

Description: MOLD HOLDER FOR MOLDS FOR MANUFACTURING BOOTS OR THE LIKE MADE OF PLASTICS Technical Field The present invention relates to a mold holder for molds for manufacturing boots or the like made of plastics. Background Art It is known that machines for the injection-molding of boots made of PVC or thermoplastic material substantially comprise a turntable provided with a series of modules, known as mold holders, and one or more injection assemblies. The molds are fitted in the mold holders. The turntable revolves at preset intervals and places the mold holders at the injectors, which inject the material in the molds through the adapted holes provided therein. With reference to Figures 1 and 2 of the accompanying drawings, a mold holder currently comprises a footing A for supporting a mold B with an upper closure cover C which is articulated thereto and is moved by a hydraulic cylinder D. The articulation is provided about an axis which is horizontal and lies to the rear with respect to the region where the mold B is inserted. The supporting footing A is provided, in a front region, with a front door E which is moved by a hydraulic cylinder, not shown, and is rotatable about the axis of a pivot F which is longitudinal with respect to the footing A. The mold B (see Figure 2) in turn comprises: — a right shell G, which is in turn divided into an upper part and a lower part; — a left shell H, which is in turn divided into an upper part and a lower part; — a right sole I and a left sole L supported by the door E; -- a left dummy mold M; - a right dummy mold N. The door E is meant, by rotating, to move the soles I or L located in a downward region at the upper position so as to be able to injection-mold boots in two or three colors during several steps. Although their use is now well-established, these mold holders have the drawback that the mold fitting operation is rather troublesome, first of all because of the shape of the mold holder and then because of the weight and dimensions of the mold (the shells G and H can weigh up to 150 kg each). The bulk of the cover C and the door E makes it necessary to fit the shells G and H by lateral insertion. In some cases, the cover C can be opened more widely in order to allow the descent from above of the shells G and H, for example by means of a bridge crane. Furthermore, the dummy molds M and N must be fitted below the footing A with difficulties as regards viewing and access. The best access for the mold fitting operations would be from the front, but front access is obstructed by the door E, whose bulk is also considerable. The complexity of the fitting of the mold in the mold holder also clashes with current market requirements, which demand short fitting times in order to avoid downtimes, with consequent productivity loss or prolonged downtimes, with the consequent need to discharge the material that is present in the injectors in order to avoid its degeneration, leading to production loss. Summary of the Invention The aim of the present invention is therefore to provide a mold holder with a structure which eliminates the drawbacks noted above in conventional types and in particular allows easier and faster removal and refitting of the molds. Within the scope of this aim. an object of the present invention is to shorten machine downtimes and accordingly increase productivity. Another object is to avoid the need to discharge the material that is present in the injector during machine downtimes. Another object is to provide a mold holder whose structure allows to automate the replacement of the molds, for example by means of pallets and computerized magazines. Another object is to provide a mold holder which can be manufactured with conventional equipment and systems. This aim, these objects and others which will become apparent hereinafter are achieved by a mold holder for molds for manufacturing boots or the like made of plastics which comprises a footing for supporting a mold, with an upper closure cover articulated to said footing and with a front door for soles which can rotate about an axis which is longitudinal with respect to the mold, characterized in that said door comprises a transverse frame which is supported by said footing, can rotate about said longitudinal axis and is arranged below the surface that supports said mold, said frame supporting at least one sole support which is pivoted so as to rotate about a corresponding axis which lies outside the front dimensions of said mold. Brief description of the drawings Further characteristics and advantages of the invention will become apparent from the detailed description of two embodiments thereof, illustrated only by way of non-limitative example in the accompanying drawings, wherein: Figures 1 and 2 are schematic side and top views of a mold holder according to the prior art; Figure 3 is a schematic side view of the mold holder according to a first embodiment of the present invention; Figure 4 is a schematic top view of the mold holder of Figure 3 without the upper cover and with the door open: Figure 5 is a partial schematic top view of the mold holder of Figure 3 without the upper cover and wήh the door closed; Figure 6 is a front view of the door related to the mold holder of Figure 3; Figure 7 is a schematic side view of the mold holder according to a second embodiment of the present invention; Figure 8 is a schematic top view of the mold holder of Figure 7 without the cover and with the door open; Figure 9 is a front view of the door related to the mold holder of Figure 7. Ways of carrying out the Invention With reference to Figures 3 to 6, a mold holder for molds for manufacturing boots or the like made of plastics according to the invention has a structure which comprises a footing 10 for supporting a mold generally designated by the reference numeral 11, which is provided with an upper cover 12 which is articulated thereto about a horizontal axis which is arranged to the rear with respect to the mold 11. The cover 12 is moved by a hydraulic opening and closure cylinder 13 which acts between the cover 12 and the footing 10. In front of the footing 10 there is a door, generally designated by the reference numeral 14, which can rotate about an axis 15 which is longitudinal with respect to the mold 11, the axis being supported by a pivot 16 which protrudes from the footing 10. The door 14 is moved by a hydraulic cylinder which is not shown in the figures for the sake of simplicity. According to the invention, the door 14 comprises a transverse frame 17 which is constituted in practice by a rod-like element which is bolted to the pivot 16 and is arranged below the surface 18 that supports the mold 11 on the footing 10. Also according to the invention, the frame 17 extends to a level which lies above the maximum dimensions of the right and left dummy molds 19 and 20 respectively, which are fixed below the footing 10 and are also fixed frontally with respect to the door 14. In this embodiment, a plate-like support 22 is pivoted to the frame 17 so that it rotates about an axis 21 which lies outside the front dimensions of the mold 11 and is perpendicular to the supporting surface 18; in this case, the support 22 supports two pairs of right and left soles 23, 24 and 25, 26 which are arranged so that the first pair faces the bottom of the mold 11 and the second pair faces the two dummy molds 19 and 20. The frame 17 and the support 22 can be locked to each other by using devices or adopting solutions of various kinds. A first solution can be to provide the frame 17 with a rotating (hinged) threaded pin 27 which enters an open slotted hole 28 of the support 22. A hexagonal locking nut 29 is screwed onto the pin 27. In a second solution, not shown, a threaded pin protrudes at right angles from the frame 17 and is adapted to fit, by passing through it, in a slotted hole of the support in order to be coupled to a locking nut which is optionally provided with a handwheel for actuation. The pivoting between the frame 17 and the support 22 must of course be provided so that they can be arranged parallel to each other and rest against each other. Accordingly, the support 22 can be conveniently opened with respect to the frame 17 during tooling, freeing the front dimensions so that the mold 11 can be extracted from the footing 10. Moreover, the rotation of the support 22 also frees the region of the dummy molds 19 and 20 and places the soles 23, 24. 25 and 26 in front of the operator, accordingly making fitting and removing less troublesome. With reference to Figures 7 to 9, a second embodiment provides for a frame 117 which is rotatably rigidly coupled to the base, now designated by the reference numeral 110, for the mold, now designated by the reference numeral 111, but in this case respective supports 122a and 122b, one for the right soles 123 and 125 and one for the left soles 124 and 126, are pivoted at both ends of the frame 117 so as to rotate about the corresponding axes that lie outside the front dimensions of the mold 111. This embodiment is less bulky than the preceding one and can be used conveniently in case of confined tooling regions and machines with several mold holder modules. In both embodiments, the mold 11 or 111 can be interposed between thermostat-controlled plates, not shown in the figures, for heating/cooling it. In order to provide a faster mold replacement operation it is in fact important for said mold to reach the operating temperature as quickly as possible after fitting. The shells are currently heated by means of electric resistors which are coupled to the machine by means of adapted plugs; the adoption of thermostat-controlled plates allows to preheat the molds before fitting, accordingly reaching the primary temperatures faster after fitting and allowing the new molds to be immediately ready for molding. In practice it has been observed that the intended aim and objects of the present invention have been achieved. The new structure of the mold holder in fact allows easier and less troublesome removal and refitting of the mold and of its parts, said operation being possible by removal and insertion in a horizontal direction. Moreover, access to the soles and to the dummy molds is now particular handy. This provides the conditions for automating the removal and refitting of the molds by means of pallets and computerized magazines similar to the solutions that have already been adopted in the field of machine tools. The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept. All the details may also be replaced with other technically equivalent elements. In practice, the materials employed, so long as they are compatible with the contingent use, as well as the dimensions, may be any according to requirements. The disclosures in Italian Patent Application No. PD98A000265 from which this application claims priority are incorporated herein by reference.

Claims: o CLAIMS 1. A mold holder for molds for manufacturing boots or the like made of plastics which comprises a footing for supporting a mold, with an upper closure cover articulated to said footing and with a front door for soles which can rotate about an axis which is. longitudinal with respect to the mold, characterized in that said door comprises a transverse frame which is supported by said footing, can rotate about said longitudinal axis and is arranged below the surface that supports said mold, said frame supporting at least one sole support which is pivoted so as to rotate about a corresponding axis which lies outside the front dimensions of said mold. 2. The mold holder according to claim 1, characterized in that said frame of said door comprises a rod-like element which is bolted to a pivot for articulation to said footing about said rotation axis, said rod-like element being arranged below the surface that supports said mold on said base. 3. The mold holder according to claim 1, characterized in that said frame of said door extends to a level which is higher than the maximum dimensions of right and left dummy molds, which are fixed below said footing and likewise frontally with respect to said door. 4. The mold holder according to claim 3, characterized in that said frame of said door pivotally supports, so that it is rotatable about said axis which lies outside the front dimensions of said mold and is perpendicular to the supporting surface thereof, said support for two pairs of right and left soles which are arranged so that a first pair of soles faces the bottom of said mold and a second pair of soles faces said dummy molds. 5. The mold holder according to claim 1, characterized in that said frame of said door pivotally supports, at both ends of said frame, respective supports, one for the right soles and one for the left soles, said supports being pivoted so as to rotate about corresponding axes which lie outside the front dimensions of said mold. 6. The mold holder according to claim 1, characterized in that said frame of said door and said support are locked to each other by means of a threaded pin which is hinged τ o said frame and enters an open slotted hole of said support, a locking nut being screwed on said pin. 7. The mold holder according to claim 1, characterized in that said frame of said door and said support are locked to each other by means of a threaded pin which protrudes from said door at right angles and is adapted to enter a slotted hole of said support in order to be coupled with a locking nut. 8. The mold holder according to claim 1, characterized in that said mold is interposed between thermostat-controlled plates for heating/cooling the mold.

Inventors: LORENZIN LORENZO, LORENZIN, LORENZO
Applicants: LORENZIN LORENZO, MAIN GROUP SPA, LORENZIN, LORENZO, MAIN GROUP S.P.A.
Application year: 1999
Main classification: B29D31
IPC codes: B29D31