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EP-4617039-B1 - MOULDING DEVICE

EP4617039B1EP 4617039 B1EP4617039 B1EP 4617039B1EP-4617039-B1

Inventors

  • ABATE, DAVIDE

Dates

Publication Date
20260506
Application Date
20240314

Claims (9)

  1. Injection moulding device (10) for plastics comprising a first mould element (11), to which mould split follower elements (14-17) are connected, and a second mould element (12), together defining a moulding cavity (18) having a longitudinal axis (Y), at least one of said first mould element (11) and second mould element (12) being movable along said longitudinal axis (Y) between a mould opening configuration and a mould closing configuration (C), each of said mould split follower elements (14-17) being movable with respect to said first mould element (11) along a respective extraction direction (E1) having a component parallel to said longitudinal axis (Y) and a component that is orthogonal to said longitudinal axis (Y); characterised in that it further comprises a positioning device (19,23;20;21;22,24) configured to ensure the correct position of said mould split follower elements (14-17) in said mould closing configuration (C), wherein said positioning device (19,23;20;21;22,24) comprises: - a plurality of centring and preloading wedge-shaped elements (19-22) fixed removably to said first mould element (11) and configured to centre and preload said mould split follower elements (14-17) with respect to said first mould element (11) and - compensating and adjusting plate inserts (23,24) configured to compensate for the wear generated by the contact between each of said centring and preloading wedge-shaped elements (19-22) and said mould split follower elements (14-17) and to adjust the position of each of said centring and preloading wedge-shaped elements (19-22) with respect to said first mould element (11), in that each centring and preloading wedge-shaped element (19;20;21;22) and the respective mould split follower element (14;15;16;17) comprise mutually opposite centring surfaces (25,26), which are tilted with respect to said longitudinal axis (Y) and configured to come mutually into contact in said mould closing configuration (C), and wherein on said first mould element (11) housing seats (27) are obtained that are configured to house respective centring and preloading wedge-shaped elements (19-22), wherein said housing seats (27) comprise bottom surfaces (28,29) that are flat and orthogonal to said longitudinal axis (Y) and shaped to restingly receive respective compensating and adjusting plate inserts (23, 24), said compensating and adjusting plate inserts (23,24) being interposed between base surfaces (30,31) of said respective centring and preloading wedge-shaped elements (19-22) and said bottom surfaces (28,29), in that said wedge-shaped elements (19-22) are configured to exert a constraining reaction on said mould split follower elements (14-17) which has a component orthogonal to said longitudinal axis (Y), and in that each of said mould split follower elements (14-17) and said first mould element (11) comprise respective mutually opposite contact surfaces (59,60) that, in said mould closing configuration (C), are in a mutual contact ensured by said constraining reaction.
  2. Injection moulding device (10) according to the preceding claim, wherein said wedge-shaped elements (19-22) and said plate inserts (23, 24) are fixed removably to said first mould element (11) inside said housing seats (27) by means of screw fixing elements (32-42), each extending in a through hole (43) obtained in a respective wedge-shaped element (19;20;21;22) and in one or more through holes (62) obtained in one or more of said interposed plate inserts (23,34), each of said screw fixing elements (32-42) being screwable into a threaded hole (61) made on a respective bottom surface (28,29) of said housing seats (27), said through hole (42) extending parallel to said longitudinal axis (Y).
  3. Injection moulding device (10) according to claim 1 or 2, wherein said mould split follower elements (14-17) are connected to said first mould element (11) by means of screw connecting elements (44-50) inserted inside respective cavities (51) obtained inside said mould split follower elements (14-17) and fixed removably to respective fixing elements (52,53) arranged on said first mould element (11).
  4. Injection moulding device (10) according to any one of the preceding claims, comprising column elements (54-56) parallel to said longitudinal axis (Y) suitable for ensuring the alignment of said first mould element (11) and said second mould element (12) in said mould closing configuration (C).
  5. Injection moulding device (10) according to any one of the preceding claims, wherein said centring surfaces (25,26) are tilted in a manner that is divergent according to a removal direction with respect to said first mould element (11).
  6. Injection moulding device (10) according to any one of the preceding claims, wherein said first mould element (11) is provided with flat resting surfaces (57,58) for restingly receiving said mould split follower elements (14-17), and wherein said bottom surfaces (28,29) are arranged at a height, along said longitudinal axis (Y), that is different with respect to said flat resting surfaces (57,58).
  7. Injection moulding device (10) according to claim 6, wherein said bottom surfaces (28,29) are arranged at a farther distance from said second mould element (12) with respect to said flat resting surfaces (57,58) in said mould closing configuration (C).
  8. Injection moulding device (10) according to any one of the preceding claims, wherein the top surface of said mould split follower elements (14-17) lies on a plane that is more distant from said bottom surfaces (28,29) than the top surface of said wedge-shaped elements (19-22).
  9. Injection moulding device (10) according to any one of the preceding claims, wherein said wedge-shaped elements (19-22) exert a constraining reaction on said mould split follower elements (14-17), having a component that is orthogonal to said longitudinal axis (Y) to ensure the contact between said respective contact surfaces (59,60) in said mould closing configuration (C).

Description

Background of the invention The present invention relates to an injection moulding device for plastics comprising mould split follower elements and provided with a device for centring and pre-loading the mould split follower elements; furthermore, the device is also configured to compensate for the wear of the mould split follower elements. State of the art In the production of objects made of plastic material through injection moulding, a mould may be provided with split followers, movable during unmoulding, so as to able to provide objects with ultra-accentuated and deep undercuts; the split followers, in particular, contribute to defining a moulding cavity designed to be filled with the plastic material to be injected. US5536161A and KR20230055057A discloses moulding devices having split followers. IT2020163278U discloses an injection mould for plastics with centring wear compensation device. For a correct moulding, it is indispensable to ensure a perfect closing of the mould given that; otherwise, the produced object could have some imbalances and could be uneven in shape and size, in particular, it could have a thickness of the plastic material that is inhomogeneous, or failing to meet the required standards in any case; therefore, the various parts that form the mould, and in particular the split followers, have surfaces, called centring surfaces, which come into mutual contact when clamping the mould and they ensure the centring between the parts. However, in recent years, there have been used increasingly resistant plastic materials, with progressively smaller wall thicknesses, and with higher pressure for injecting plastic material into the moulding cavity; therefore, there has been the need for using increasingly higher mould clamping forces. However, the increase of clamping forces results in a greater friction between the centring surfaces, and therefore an accelerated wear phenomenon thereof. The operative effectiveness of the centring surfaces is therefore jeopardised prematurely; in other words, the centring surfaces are soon no longer able to perform the desired function. In the event of moulds provided with split followers, the latter are particularly affected by the wear out phenomenon mentioned above, and it is difficult to restore the correct positioning of the parts of the mould during the moulding cycle without external maintenance operations which could require rather long times. In the light of the drawbacks outlined above, it would therefore be desirable to improve the current moulds for producing objects made of plastic material through injection moulding. In particular, it would be strongly desirable that moulds provided with split followers be provided with a device capable of easily and quickly compensating the wear out of the split followers, therefore ensuring the centring thereof; besides extending the life of the mould, this would also allow to avoid the undesired and long maintenance operations. Objects of the invention An object of the present invention is to improve the current injection moulding devices. Another object of the present invention is to provide an injection moulding device for plastics, provided with split followers, capable of easily and quickly compensating the wear out of the split followers. A further object of the present invention is to provide a moulding device capable of ensuring high quality and dimensional precision of the moulded products over time. A further object of the present invention is to provide an injection moulding device that reduces maintenance operations to the minimum. Yet a further object of the present invention is to provide an injection moulding device provided with a significantly increased service life. Brief description of the drawings These and other characteristics according to the present invention will be more apparent from the description that follows with reference to the attached drawings, in which: Fig.1 is a cross-sectional partial view of a moulding device according to the invention, in a mould closing configuration;Fig.2 is a perspective view of the moulding device Fig.1 with elements removed;Fig.3 is a front view of Fig.2;Fig.4 is a top view of Fig.2;Fig.5 is a further front view of the moulding device of Fig. 1 with further elements removed;Fig.6 is an enlarged detail of Fig.5. Detailed description of the invention With reference to the Figures, there is shown an injection moulding device 10 for plastics, in particular for moulding containers, such as - by way of non-limiting example - containers for coatings. Fig.1 shows a portion of the injection moulding device 10 for plastics in a mould closing configuration C. The moulding device 10 comprises a first mould element 11 and a second mould element 12. In particular, as better shown in Figs.2-4, the first mould element 11 is connected to mould split follower elements 14-17. The first mould element 11, the second mould element 12 and the mould split follower eleme