AU597499B2

AU597499B2 - Injection core for two component injection moulding

Info

Publication number: AU597499B2
Application number: AU18064/88A
Authority: AU
Inventors: Frank Schellenbach
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-06-04
Filing date: 1988-06-03
Publication date: 1990-05-31
Anticipated expiration: 2008-06-03
Also published as: EP0315660A1; DE3718782A1; EP0315660B1; JPH02500182A; WO1988009715A1; JPH0684028B2; ATE71013T1; AU5316490A; DE3867430D1; AU1806488A; DE3718782C2; AU626656B2

Abstract

An injection core for two-component injection moulding, in particular of plastic stoppers for bottles and similar containers, solves the problem caused by the fact that injection cores in a single piece can only be moved with difficulty, if at all, a predetermined distance away from the first injected body, because of the design of the latter, in order to create a gap for injecting the second body. The injection core is composed of a first (1) and of a second (2) partial cores. The first partial core can be moved a predetermined distance (A, A') away from the first injected body after injecting the first substance, and the second substance can then be injected in the gap thus obtained in order to form the second injected body.

Description

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P~'WELTORGANISATION-D ESIS EIGENTUM INTERNATIONALE ANMELD"G 6F7FNT H1 Ac1l EM VERTRAG OBER DIE INTERNATIONALE ZUSAMMF kITJ F 1 GIE&1:S PATENTWESENS (PCT) (51) Internationale Patentklassifikation 4: (11) Internationale Verdiffentlichungsnummer: WO088/ 09715 B29C 45/16 Al (43) Internationales Veroffentlichungsdatum: 15. Dezember 1988 (15.12.88) (21) Internationa2es Aktenzeicben: PCT/DE88/00331 us.

(22) Internationales Anmneldedatumn: 3. Juni 1988 (03.06.88) Veioffentlicht (31)Pririttsakenzichn: P37 8 72.1 Mit in ternationalem Recherchenbericht.

(31)Prirititsateneicen: 37 8 72.1Mit gednderten Ansprilcben.

(32) Prioritatsdatum: 4. Juni 1987 (0A.06.87) (71)(72) Anmielder mid Erfinder: SCHELLENBACH, Frank 9 MAR 1989 [DE/DE]; Tijbinger Allee 22, D-7032 Sindelfingen

AUSTRALIAN

(74) Anwilte: BARDEHLE, Heinz usw.; Galileiplatz 1, D- 4Jjq 89 8000 Mfinchen 80 4A JNr OFF8C (81) Bestimmungsstaaten: AT (europ~iisches Patent), AU, BE E AETOFC (europiiisches Patent), BR, CH (europtiisches Patent), DE (europa1isches Patent), FR (europaiisches Pate.-it), GB (europdiisches Patent), IT (europaiisches Patent), JP, LU (europdtisches Patent), NL (europit,,ches Patent), SE (europaiisches Patent), (54) Title: INJECTION CORE FOR TWO-COMPONENT INJECTION MOULDING (54) Bezeichnung: SPRITZKERN FOR DIE VERWENDUNG BET ETNEM ZWEI-STQ.EEE--'PP IT7GWFSSF This ducumen; coutans thi (57) Abstract amendments made wider Sectioni 49.

An injection core for two-component injection moulding, in particular of plastic stoppers for bottles and similar containers, solves the problem caused by the fact that injection cores in a single piece~ can only be moved with difficulty, if at all, a predetermined distance away from the first injected body, because of the design and Is orrecm for P~i t yh of the latter, in order to create a gap for injecting the second body. The injection core is composed of a first and of a second partial cores. The first partial I core can be moved a predetermined distance away from the first injected body after injecting the first substance, and the second substance can then be injected in the gap thus obtained in order to form the second injected body.

(57) ZusammenfassungA Vorgestellt wird ein Spritzkern f~r die Verwendung bei dem Zwei-Storfe- Spritzgiessen, insbesondere ffir die Verwendung bei dem Zwei-Stoffe-Spritzgiessen

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von Kunststoffverschlilssen fMr Flaschen und dergleichen Behaltnisse. Die Erfindung l6st das Problem, dass einstilckige Spritzkerne wegen der Gestaltung des ersten Spritzlings nur unter Schwierigkeiten oder gar nicht um einen vorbestimmten Betrag von dem ersten Spritzling entfernbar sind, um einen Zwischenraum fMr die Einspritzung des zweiten Spritzlinges zu bilden. Dem trllgt die Ert'indung dadurch Rechnung, dass der Spritzkern aus einem ersten und einem zweiten Teilkern (2) bestehit, und dass der einec Teilkern nach dem Spritzen des ersten Stoffes um einen vorbestimimbaren Eetrag relativ zu dem ersten Spritziing entfernbar und in den entstandenien Zwischenraum der zweite Stoff zur Bildung des zweiten Spritzlings einspritzbar ist,

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1- 18 19 20 21 Sos 22 23 100 0 24 26 27 28 1600 29 *31 32 33 OS 5 34 35 36 37 0 i S_ 38 "INJECTION CORE FOR TWO-COMPONENT INJECTION MOULDING" The invention relates to an injection co7'q for use in injection moulding where the core consists of a first and a second sub-core and the one sub-core after injecting the first substance is displaceable by a predetermined amount relative to the first moulding and the second substance can be injected into the resulting intermediate space to form the second moulding. An injection core of this type is known from the Austrian Patent 378,498.

In the parallel, non-prepublished German patent application P3803680.7-16 of applicant, protection is 8ought for a method for producing an airtight plastic closure for bottles and similar containers, by which two-component injection moulding, known per se, is employed.

The method is used in a manner such that the so-called mould nest is configured in the form of the actual closure cap, where the interior space of this closure cap is -omplementarily enclosed by an injection core in the usual manner.

According to the method suggested in that application, the injection core is then displaced by predetermiiied amount relative to the first moulding and the second substance is injected into the so created intermediate space. This second substance is usually designed as sealant with respect to the bottle to be closed.

The method described in that patent application, which uses two-component injection moulding, has great advantages for producing plastic closures for bottles and similar containers, which arise both in the production and also the later use of such closures.

According to the above~-escribed method, it remains up to the skilled person how he realizes the relative movement of

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36 37 38 the injection core from the closure produced with the first substance. Since bottle closures usually are provided with threadings on the inside, with which they can be screwed on to the bottle to be closed, it would be possible to screw back the injection core by a predetermined amount from the previously molded closure, and then to inject the secon substance into the so created intermediate space.

The invention provides a different possibility, according to which the injection core can be displaced by a predetermined amount from the closure.

In accordance with the invention, the injection core consists of a first and second sub-core or partial core.

This division into "two sub-cores opens the possibility of retaining one sub-core at its position and only displacing the other sub-core from the closure by a predetermined amount. This measure makes it possible, to structure the outer sub-core so that it represents the mould for the threading to be formed on the closure. In such a case, this sub-core would be held fixed, while the inner sub-core is drawn back to form the intermediate space for injecting the second substance. From the Austrian Patent AT 378,498, in particular in Fig. 2 and 3 in conjunction with page 5, line 53, an injection core with the features of the preamble of claim 1 is known. This two-part injection core of the art is employed in a method for producing sleeve sockets for pipeline connections by injection moulding. The connection and sealing problem for pipe connections however are of a different type than those to be solved for bottle closures which are fixed as a cap.

When the known pipe connection should withstand a high internal pressure, then according to page 5, lines 34-41 in conjunction with Fig. 1, a tension bushing is inserted axially between the sealing lips. With t;ni tension bushing, the inner side of the sealing is pressed cver a large surface against the outer circumference of the inner 900228araspe.027. 18064con 1~7~t~l~ -3- 1 pipe and the tightness of the seal in increased.

2 3 A closure technique of" this type cannot be used for a 4 bottle closure, because an additional tension sleeve or bushing would be too complication and because the force on 6 the closure cap resulting from the high inside pressure, 7 which as opposed to a pipe connection acts primarily in the 8 axial direction, could not be sufficiently contained.

9 The object of the invention therefore is to design an 11 injection core of the assumed type, so that the finished 12 mould which is easily handled in practice, can reliably 13 withstand all separation forces arising in the axial 14 direction.

16 According to the present invention there is provided a core 17 assembly for use in an injection mould for producing a two 18 component moulding in which a first component of the 19 moulding is produced by injecting a first substance into the O..20 mould, the core assembly comprising a first sub-core which $se 21 is displaceable relative to the first component of the 22 moulding after the first component has been formed so as to 23 provide an intermediate space between the first component of 24 the moulding and the first sub-core so that a second substance can be injected into the intermediate space to 26 form a second component of the moulding, the core assembly 27 further component of the moulding, the core assembly further 28 including a second sub-core having a profiled section for 29 use in the formation of a part of the first component of the moulding.

S31 32 Preferably the second sub-core is displaceable relative to 33 the first sub-core and to the first component of the .~34 moulding.

Soo:0 36 The first sub-core may have a first profile section for use 37 and formation of the second component of the moulding. That IAV 38 profile section may comprise a cone which projects into a -4- I *0O 0 *a 0 *0 *0 0.

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mould nest part of the mould. The first profiled section may further or alternatively include a section such as to form a circular sealing bead on the second component.

Preferably the first sub-core comprises an inner sub-core and the second sub-core comprises an outer sub-core.

According to another aspect of the present invention there is provided apparatus for injection moulding plastics closures for bottles comprising a mould which includes a mould nest and a core assembly as described above, the core assembly being receivable within the non mould nest.

An injection core in accordance with the invention or its preferred embodiments makes it possible to withdraw the inner sub-core while the outer sub-core remains at its original location. In particular, those types of inside and/or outside profiles can be produced which do not allow the movement of a one-part injection core after injecting the first substance or this only with difficulty.

In accordance with the invention, the axial force on a closure cap is contained by interior profile elements, which simultaneously provide the force for sealing. Such profile elements could be threadings, ridges or recesses, which are formed on the initially moulded closure cap and which hinder the necessary movement of the injection core. The inner sub-core alone, however, can be easily moved to expose the facing surface of the closure cap for injection the second moulding, Preferred embodiments of the invention will hereinafter be described with reference to the accompanying drawings.

The invention is discussed in detail in conjunction with Figs. 1 and 2 and the technical features are illustrated.

Fig. 1 shows an axial cross section of an injection core j, t CL- i

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11 12 13 14 16 1; 1 19 20 see* 21 22 00 "00* 23 24 26 27

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28 29 30 *e Oe 31 32 33 S. CS 34 35 36 37 -A'3 consisting of a first sub-core 1 and a second sub-core 2.

In addition, a moulding 3 is shown, i.e. a closure cap for a bottle, which has already been produced by injecting a first substance. This moulding or casting 3 comprises a threading 4, which results through a complementary recess in the second sub-core 2.

The second substance is injected after the first sub-core 1 has been displaced by a predetermined amount A with respect to the moulding 3. The distance A is for example 0.7 mm.

The division of the injection core into a first and second sub-core makes it possible for example to also provide the moulding 3 with circular ridges or vertical indentations instead of threadings or in addition to threadings, which would not allow the rotation of the injection core after completion of the moulding 3. However since the second subcore 2 remains fixed with respect to the moulding 3 during production of the closure and only the first sub-core 1 is moved axially, the intermediate space required for injecting the second substance can be created, while ridges or the like present on the moulding 3 are not an obstacle.

However, in an embodiment of the invention the outer subcore 2 can also be displaceable relative to the inner subcore 1 and within the first moulding 3 by an amount A'.

This can take place for example by screwing out the sub-core 2 by an amount Through the varying distances A and A' for the inner sub-core 1 and the outer sub-core 2, the possibility exists to provide the second moulding with a complicated form. For example the sealant injected with the second substance can be thinner in the outer region as in the inner region.

It is not important for the invention whether the two subcores are rotated with respect to one another by means of threadings or whether they are axially shifted. Decisive is only that the invention provides the desired intermediate space for injecting the second substance, without this being sc -6 1 hindered by obstacles on the moulding 3.

2 19 20 21 22 23 e~24 26 27 28 29 31 32 33 5 34 36 37 t CIA 38 In another embodiment of the invention, the inner sub-core 1 is provided with profile elements which serve in forming the second moulding. Two examples of this are illustrated in Fig. 2.

Reference sign 5 designates a cone projecting into the mould nest, which provides a small opening in the closure cap when making the first moulding 3. After withdrawing the inner sub-core 1 and injection the sealant, a position of relatively small resistance results in the middle. The cone on the one one hand consists o~f the second softer substance, and on the other hand, the closure cap 3 is thinner in the area around the cone as in the other regions.

Thus a safeguard against bursting can be provided in the closure cap 3 in a simple manner. With high pressure in the bottle, it cannot happen that the bottle is destroyed or the cap pops off. Moreover, the cone 5 is only pushed out of the air-tight closure cap 3. The high pressure can then be released through the small opening, without a large amount of liquid running out. For example, for a thickness a A 0.7 mm, the cone-shaped stopper can withstand an internal pressure of 8 bar. For example for A 1 mm, this limit increases to 10 bar, while for A 2 mm it is about 14 bar.

A further example of a useful profile element on the second moulding is the sealing bead 6. In the embodiment in Fig.

2, it is provided as a circular groove 6 on the inside of the sub-core 1. The circular sealing bead 6 is provided on the axially loaded contact surface of the second moulding.

This profile element serves to adapt the sealing to the form of the bottle neck to be closed. Due to the adapted contact surface, either the allowable gas pressure can be increased or the contact pressure providing the sealing between the closure cap and the container edge can be decreased. With such profile elements, the skilled person acquires the 7 1 possibility to adapt the closure cap produced by the 2 injection core of the present invention to various 3 requirements.

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Claims

8- THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS: i. A core assembly for use in an injection mould for producing a two component moulding in which a first component of the moulding is produced by injecting a first substance into the mould, the core assembly comprising a first sub core which is displaceable relative to the first component of the moulding after the first component has been formed so as to provide an intermediate space between the first component of the moulding and the first sub core so that a second substance can be injected into the intermediate space to form a second component of the moulding, the core assembly further including a second sub core having a profiled section for use in the formation of a part of the first component of the moulding. 2. A core assembly according to claim 1 wherein said second Sub-core is displaceable relative to the first sub core and to the first component of the moulding. *o*g 3. A core assembly according to claim 1 or claim 2 wherein see* said first sub- core has a first profiled section for use in S.. *Xo the formation of the second component of the moulding. 4. A core assembly according to claim 3 wherein the mould comprises a mould nest and the first profiled section comprises a cone which projects into the mould nest. em.. gee• o 5. A core assembly according to claim 3 or claim 4 wherein the first profiled section is such as to form a circular S" sealing bead on the second component of the moulding. 6. A core assembly according to any preceding claim o oo S wherein said first sub-core comprises an inner sub core and said second sub core comprises an outer sub core relative to said inner sub core. 7. Apparatus for injection moulding of plastics closures r I -9 for bottles comprising a mould which includes a mould nest and a core assembly according to any preceding claim said core assembly being receivable within said mould nest. 8. A core assembly substantially as hereinbefore described with reference to the accompanying drawings.
9. Apparatus for injection moulding of plastics closures substantially as hereinbefore described with reference to the accompanying drawings. 6SO* 0 c OS*O @6 0 q SS 6 Dated this 28th day of February, 1990. S e g. 6O eo 0 0* @0 C 0 OS SC 5 5, 0 DAVIES COLLISON Patent Attorneys for FRANK SCHELLENBACH 900228,araspe.027,18064cl,