WO2004065094A1

WO2004065094A1 - Apparatus for injection molding plastic materials using in-mould labelling

Info

Publication number: WO2004065094A1
Application number: PCT/IB2003/006144
Authority: WO
Inventors: Guido Nussio
Original assignee: Tecnowerk S.R.L.
Priority date: 2003-01-22
Filing date: 2003-12-23
Publication date: 2004-08-05
Also published as: ITPD20030009A1; AU2003288625A1

Abstract

Apparatus for molding plastic materials comprising a male die figure and a negative die figure (14), moving reciprocally, in order to assume a contact position which defines a moulding cavity (15) and a spread apart position which allows to introduce into said moulding cavity a decorated mono- or multilayer sheet (16); the peculiarity of this apparatus lays in that it comprises sucking means to keep said at least one decorated sheet (16) adhering to said male die figure (13) during the step when said male (13) and negative die figures pass from the spread apart position to the contact position. The apparatus overcomes the drawbacks found in the known state of the art, as it allows to produce containers of cylindric, truncated cone or similar shapes at low costs.

Description

DESCRIPTION

APPARATUS FOR INJECTION MOLDING OF PLASTIC MATERIALS USING IN-MOULD LABELLING

The present invention refers to an apparatus for molding plastic materials especially, but not exclusively, to be used for the injection 5 moulding of containers of cylindric and truncated cone and similar shapes with outside decoration.

Such containers are substantially formed by an open tray and a closing lid reciprocally matchable by means of the rims. The tray and lid are constituted of a plastic bearing structure obtained through injection

10 moulding and of a decorated monolayer or multilayer sheet adhering to the outside surface of the structure. Nowadays, this type of containers is carried out according to the procedure called "in mould labelling". Substantially, this procedure consists in injecting melted plastics into a moulding cavity where a decorated sheet has been appropriately inserted,

15 owing to the temperature and pressure conditions in said cavity the sheet will adhere to the structure which is being moulded.

In the known state of the art, the following production apparatuses carry out the above-mentioned procedure:

A first apparatus is known from the Italian patent for industrial

20 invention referring to an "Apparatus for injection moulding of plastics with incorporated label positioner" issued by No. 1270572 dated 06.05.1997 on behalf of the applicant of this patent application. This apparatus is essentially formed by injection moulding means for plastics and by manipulator means introducing the decorated sheets to the inside of said

25 moulding means. In details, these moulding means comprise a traditional type of die formed by one pair of dies called "male" and "negative" defining a moulding cavity conformed according to the wanted container. The pairs of dies are moving reciprocally in longitudinal direction in order to define a spread apart position called "by open die" and a contact position called "by

30 closed die". By open die the distance existing between the die figures permits to introduce a decorated sheet inside the moulding cavity. By closed die the injection of plastics takes place distributing itself inside the cavity. The foreseen manipulator means are constituted of an automatic device to withdraw/drop one decorated sheet at a time from a stock of sheets positioned on the top of the male die figure. Such means are moving in vertical and longitudinal direction. The working of the apparatus is as follows. During the passing step from closed die to open die, the withdraw/drop means perform through a sequence of movements the withdrawing of the head sheet from the stock, its frontal introduction into the moulding cavity, and then they return to the start position to perform a new step. After this step follows, by closed die, the injection of the plastic material and on its outer surface the above-mentioned sheet will fix itself.

A second known type of apparatus comprises the above moulding means and an automatic device for manipulation of the decorated sheet positioned near to the above moulding means. The automatic device provides, as in above example, to withdraw a decorated sheet from the stock and to introduce it into the moulding cavity. In details the device is formed by a trainable horizontal arm which at one end bears a plane placed troncated cone spindle which turns around its own horizontal axis. On the spindle surface are made a plurality of openings connected with an air pump. In this specific case the decorated sheets are shaped as an angolar portion of a ring and piled beside the start position of the spindle. The device works in the following way. The rotating spindle is guided by the arm on the surface of the decorated head sheet of the stocked pile in order to execute the coiling step. In this way, by means of the sucking action caused through the openings, the decorated sheet will coil entirely onto the spindle. Therefore, by open die, the arm moves the spindle to the inside of the moulding cavity. Here the sucking is interrupted so that the decorated sheet lies down on the cavity sides. Then, the sheet is made adhering to the cavity sides by means of an electric discharge. The working then continues as described above.

The principal drawback of the first device type consists in the fact that it does not permit producing containers of cilindric, troncated cone and similar shapes with decorated outside. Such production is hindered by the fact that the introduction of the decorated sheet to the cavity is made from the front side. This means that the decorated sheet will lie on the bottom of the cavity and not on the sides as required. Such inconvenient could be won using a spindle similar to that of the second device instead of the withdraw/drop means forseen in the first device type. Anyhow, this solution results technically not achievable due to considerable mechanical and electronic complexity. The principal drawbacks of second device type are recognized in the following aspects. The foreseen manipulation device involves considerable higher costs than the manipulator means of first device owing to the remarkable mechanical and electronis complexity. This fact influences negatively the final container price. Furthermore, above device is destined to operate in a position near to the moulding apparatus. It is also well-known that the surface occupied by this device type will extend onto the operating area of the moulding apparatus. Space occupied in this way reduces considerably the useful surface inside a production plant.

The principal aim of the present invention is to carry out an apparatus for moulding plastic materials which allows to overcome the inconveniences found in the known state of the art.

Within the scope of this aim, an object of this invention is set up an apparatus characterized by the constructive simplicity typical of first mentioned device but allowing to carry out containers in above-mentioned shapes and decorated on the outside.

A second object of this invention is set up an apparatus which does not require more operating area than the first mentioned type of apparatus.

A further, but not last, object of the invention is to set up an apparatus operating at the working speed actually achieved in the sector moulding plastics through injection. This aim, as well as these and other objects which will become apparent hereinafter, are achieved by an apparatus for injection moulding of plastics comprising a male die figure and a negative die figure, moving reciprocally, in order to assume a contact position which defines a moulding cavity and a spread apart position which allows to introduce a decorated mono- or multilayer sheet into the above-mentioned moulding cavity, characterized by that it comprising sucking means to keep said at least one decorated sheet adhering to said male die figure during the step when said male and negative die figures pass from spread apart position to contact position.

Further features and advantages will become apparent even more from the description of a preferred embodiment of the invention illustrated as indication, but not as limitation, in the attached three drawings, where:

- figure 1 is a side view of one appliance of the apparatus according to the invention;

- figure 2 is a side detailed view, partially longitudinally sectioned, of said apparatus with die figures in spread apart position;

- figure 3 is a detailed view of the male die figure in front section taken along the plan Ill-Ill of figure 2. - figure 4 is a side detailed view, partly longitudinally sectioned, of said apparatus with die figures in contact position.

- figures 5, 6, 7, 8, 9 and 10 are views explaining schematically the step sequence of the working apparatus.

With reference to the attached drawings, and initially to figure 1 , the apparatus, generally indicated by reference number 11 , is mounted on a machine for the injection moulding of plastics indicated with reference number 12. In details, said apparatus 11 is constituted of a male die figure and of a negative die figure generally indicated with reference numbers 13 and 14. Said die figures 13 and 14 are moving reciprocally in order to assume a contact position, as represented in figure 4, thus defining a moulding cavity 15 and a spread apart position, as represented in figures 1 and 2, allowing to introduce into the moulding cavity 15 a well-known decorated mono- or multilayer sheet indicated with reference number 16. The male die figure 13 comprises a plate 17 for stirruping to the machine 12 and an appendix 18. In the represented embodiment this appendix 18 is cylindric, but could also be troncated cone shaped or similar. As it is visible in figures 2 and 4, the stirrup plate 17 is conformed to define a central space. As it is visible in the same figures, the appendix 18 jutt out the plate 17 in the moving direction of the above-mentioned die figures 13 and 14. Such appendix 18 is composed of a shell 19 and a mushroom shaped body generally indicated with reference number 20. When die figures 13 and 14 are in spread apart position, then body 20 will be in advanced position compared with shell 19 as illustrated in figure 2. When figures 13 and 14 are in contact position, then body 20 will be in drawn back position leaning against shell 19 as illustrated in figure 4. Said shell 19 has a central lengthwise passing hole 21 debouching in the space. The mushroom body 20 is made of a stem 22 and a head 23 joined with screws. In this way, stem 22 is inserted in the central passing hole 21 and head 23 closes the front of shell 19. Inside said space obtained in stirrup plate 17 operates a plate 24 being frontally placed to passing hole 21. Said plate 24 is frontally connected to stem 22 from the side opposite head 23. Said plate 24 is pressed from the back by elastic elements as springs 25 as drafted in figures 2 and 4. Furthermore, a cilindric size 26 jutts out of the frontside of plate 24 penetrating a passing hole (without reference number) made lengthwise in stirrup plate 17. As it is visible in figure 2, said size 26 jutts out of the plate surface 17 when body 20 is in above-mentioned advanced position. The negative die figure 14 is equipped with a cavity 27 receiving appendix 18 when said die figures 13 and 14 are in contact position. On the other hand, when said die figures 13 and 14 are in spread apart position then cavity 27 is faced towards appendix 18. In the bottom of said cavity 27 is obtained the inlet channel 28 for the fused plastics. Said moulding cavity 15 is therefore defined by the gap existing between cavity 27 and appendix 18 when die figures 13 and 14 are in contact position. The apparatus 11 furthermore comprises sucking means 29 with the function to keep the decorated sheet 16 adhering to male die figure 13 when die figures 13 and 14 are brought from spread apart position to contact position. In details, such sucking means 29 are constituted by a sucking slot 30 defined on male die figure 13. In details, such sucking slot 30 is obtained on appendix 18 and is extending all around it. Said sucking slot 30 is connected to an air pump (not illustrated) through a duct 31 extending into appendix 18. As illustrated in figures 3 and 7 such duct debouches in said slot 30 immediately next to the first stay area of the decorated sheet 16. As it is visible particularly in figure 2, slot 30 is defined by the gap between the end of shell 19 and the head 23 of body 20 when the latter will be in advanced position. Furthermore, as it is visible in figure 2, the width of slot 30 is equal to the protrusion length of size 26 compared with the surface of stirrup plate 17. The moulding apparatus 11 is slaved by a manipulator device 32 of the generally known type positioned on the top of male die figure 13 which through moving sequence withdraws the head sheet of the piled decorated sheets and deposits it on appendix 18 as indicated in details in the below working description.

With reference to the figures of attached drawings, and particularly to figures 5 to 10 of drawing sheet 3/3, the working of apparatus 11 is as follows. In figure 5 is illustrated the first step being the injection of fused plastics. The die figures 13 and 14 are in contact position. The manipulator device 32 is withdrawing a decorated sheet 16. In figure 6, the die figures 13 and 14 are in spread apart position. The spreading apart of die figures 13 and 14 releases the elastic elements 25 which act on plate 24 so that mushroom body 20 assumes the advanced position forming slot 30 and size 26 jutts out of the stirrup plate 17. The manipulator device 32 is depositing the decorated sheet 16 on appendix 18. Between the figures 7 and 8 it is visible how the sucking crown created near to sucking slot 30 provides to make adhere progressively the decorated sheet 16 to the surface of appendix 18. Figure 9 is the step immediately before the injection step. During the approach step of die figures 13 and 14, the negative die figure 13 gets even with the protuding end of size 26 forcing it to retire until the surface edge of stirrup plate 17. Together with size 26 retires also plate 24 which drags mushroom body 18 in withdraw position and thus occluding sucking slot 30. During the above-mentioned approaching of die figures 13 and 14 the decorated sheet 16 is transported inside the moulding cavity 15. Die figures 13 and 14 are now in contact position and the sucking action has stopped. So the decorated sheet comes off in natural way from the surface of appendix 18 and deposits itself on the sides of cavity 27. In figure 10 is illustrated the conclusive working step injecting fused plastics as foreseen in the known moulding apparatuses. The working then starts again from the step illustrated in figure 5.

In practice it has been observed that this apparatus achieves the intended aims and objects overcoming the inconveniences found in the known state of the art. In fact, the preferred solution to add to the male die figure the action of transporting the decorated sheet inside the moulding cavity allows to deposit correctly the decorated sheet and to use a manipulator device of simple construction positioned over the moulding machine thus obtaining a notable cost reduction. Furthermore, the foreseen sucking means constructively prove to be simpler than those in the known state of the art and also more functional as they do not require rotation in order to coil the sheet.

In the practised embodiment the materials used, the forms, the dimensions and the execution details may be different from these here indicated, but technically equivalent to these, without for this reason to exeed the limits of the law for this invention.

Claims

CLAIMS 1. Apparatus for molding plastic materials comprising a male die figure and a negative die figure, moving reciprocally, in order to assume a contact position which defines a moulding cavity and a spread apart position which allows to introduce into said moulding cavity a decorated mono- or multilayer sheet, characterized by that it comprises sucking means to keep said at least one decorated sheet adhering to said male die figure during the step when said male and negative die figures pass from spread apart position to contact position.

2. Apparatus, according to claim 1 , characterized by that said male die figure comprises a stirrup plate and an appendix of cylindric, troncated cone or similar shape.

3. Apparatus, according to claim 2, characterized by that said stirrup plate comprises a central space.

4. Apparatus, according to claim 2, characterized by that said appendix jutts out of said plate in the moving direction of said die figures.

5. Apparatus, according to claim 2, characterized by that said appendix comprises a shell and a mushroom shaped body which assumes an advanced position compared with said shell when said die figures are in spread apart position and a drawn back position when said die figures are in contact position.

6. Apparatus, according to claim 5, characterized by that said shell comprises a central lengthwise passing hole debouching in said space.

7. Apparatus, according to claim 5, characterized by that said mushroom body comprises a stem and a head joined together by means of screws.

8. Apparatus, according to claims 6 and 7, characterized by that said stem is inserted in said central hole and said head closes said shell front.

9. Apparatus, according to claims 3 and 6, characterized by that it comprises a plate housed in said space, said plate being disposed frontally compared with said passing hole made in said shell.

10. Apparatus, according to claims 8 and 9, characterized by that said stem is connected from the side opposite said head to the front side of said plate.

11. Apparatus, according to claim 9, characterized by that it comprises elastic elements pressing on the back of said plate.

12. Apparatus, according to claim 9, characterized by that it comprises a cilindric size jutting out of the front side of said plate and penetrating a passing hole made lenghtwise in said stirrup plate, said size being in a protuding position compared with said plate when said mushroom body is in advanced position compared with said shell.

13. Apparatus, according to claim 2, characterized by that said negative die figure comprises a cavity receiving said appendix formed on said male die figure when said die figures are in contact position.

14. Apparatus, according to claim 2, characterized by that said cavity is faced to said appendix when said die figures are in spread apart position.

15. Apparatus, according to claim 13, characterized by that the inlet of said fused plastics is obtained on the bottom of said cavity.

16. Apparatus, according to claims 1 , 2 and 13, characterized by that said moulding cavity is defined by the gap existing between said appendix and said cavity when said die figures are in contact position.

17. Apparatus, according to claim 1 , characterized by that said sucking means comprise a suction slot defined on said male die figure.

18. Apparatus, according to claims 2 and 17, characterized by that said slot is obtained on said appendix.

19. Apparatus, according to claim 18, characterized by that said suction slot is extending all around said appendix.

20. Apparatus, according to claim 17, characterized by that said slot is connected to an air pump through a duct obtained in said appendix.

21. Apparatus, according to claim 20, characterized by that said duct debouches in said slot immediately next to the first stay area of said decorated sheet on said appendix.

22. Apparatus, according to claims 5, 7 and 17, characterized by that said slot is defined by the gap between said shell and the head of said mushroom body when the latter is in advanced position compared with said shell.

23. Apparatus, according to claims 12 and 17, characterized by that the width of said slot is equal to the protrusion length of said size compared with said plate.

24. Apparatus, according to claim 1 , characterized by that it comprises a manipulator device positioned on the top of said male die figure which withdraws through moving sequence the head sheet from a pile of decorated sheets placed above said negative die figure and deposits it on said male die figure.