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(11) | EP 1 181 998 B1 |
| (12) | EUROPEAN PATENT SPECIFICATION |
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| (54) |
Equaliser for forced closure of suction valves in die-casting moulds Entzerrer für Zwangsverschluss von Einlassventilen in Druckgiessformen Egaliseur pour la fermeture forcée de clapets d'aspiration dans les moules de coulée sous pression |
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| Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). |
[0001] This invention concerns an equaliser device to aid closure of a suction valve for the discharge of air and gas from die-casting moulds.
[0002] In the die-casting technique, moulds are used which have a mobile part and a fixed part which can be closed together and may be equipped with a suction valve for evacuating air and gas from the mould thus preventing their inclusion in the die-cast pieces.
[0003] A suction valve for such use normally consists of a body to be fixed to the mobile part of the mould and a cover to be fixed to the fixed part of the mould, or vice-versa, in such a way that opening and closing of the mould coincide with opening and closing of the valve. To ensure correct closure against the internal pressures and thus avoid drawing between body and cover, the valve may be kept under tension by a spring loaded equaliser device that acts perpendicularly on the valve when the mould is closed, keeping the two elements of the valve closely locked one to the other.
[0004] Equalisers incorporating Belleville washers acting on a piston are well known, where the washers are all overlapped in an assembly with an inappropriate layout which limits performance of the device and which may lead to the washers breaking after only a short time. In fact it has been ascertained that when multiple Belleville washers are overlapped they place stress one on the other in a dissimilar manner and the sum of their frictions reduces the efficiency and flexible reaction of the assembly. In other words, the power of the device does not correspond to the summation of the load of the washers but is reduced, and even the intactness of the washers comes to be jeopardised.
[0005] For example, US 4 027 726 discloses a venting valve for die-casting moulds provided with an equaliser in which the washers are in an alternating arrangement such that the edge of one washer abuts the edge of the adjacent washer and the centre of this washer abuts the centre of the next, and so on. Such a classical arrangement of Belleville washers avoids friction between any two washers, but requires some attention when assembling the stack of washers on the common piston rod.
[0006] One aim of this invention is to remedy the inconveniencies and disadvantages of the well known technique employed in equalisers for the closure of suction valves in die-casting moulds by means of a new, original positioning of the washers in relation to a thrust piston.
[0007] Another aim of the invention is to supply, for the above-mentioned purpose, a spring loaded equaliser that is more efficient and reliable and above all sectional in accordance with necessity and depending on the load required.
[0008] A further aim is to supply an equaliser that can be set up as a unit in itself or integrated directly into a cover die with the suction valve.
[0010] Greater details of the invention will be clear from the following description, given with reference to the attached indicative but not limitative drawings in which:
Fig. 1 shows the equaliser in axial section;
Fig. 2 shows an example of application of the invention equaliser.
[0011] In these drawings the equaliser is shown globally with 11 and associated with a suction valve 12 applied to a die-casting mould 13.
[0012] Suction valve 12 includes a first element or half-valve 12' and a second element or half-valve 12" which can be closed one on the other. The first half-valve 12' is attached to fixed part 13' of the mould by means of support block 14'; the second half-valve 12" is attached to mobile part 13" of the mould by means of support block 14". This in such a way that opening and closing of the mould correspond to opening and closing of the valve.
[0013] In the invention the equaliser 11 consists of an external body or casing 15, a central piston 16 guided axially on a head 17, and a multiplicity of Belleville washers 18 placed concentrically between piston 16 and external body 15.
[0014] The equaliser is located between support block 14" and mobile half-valve 12" with guide head 17 connected to the said half-valve and piston 16 projecting axially from body 15, and abutting with support block 14" or vice versa.
[0015] In equaliser 11 the Belleville washers are set in groups, preferably in threes 18', on several parallel levels along piston 16. Each trio of Belleville washers 18 - Fig. 1 - rests axially with one part on a collar 19 applied to piston 16 and the other against support washer 20 inside body 15.
[0016] The body may consist of two or more sectional segments in order to be able to set its length on the basis of the selected number of Belleville washers, and around each group or trio of Belleville washers there may be spacer 21, either separate or solid with an adjacent washer 20.
[0017] At least one spacer 21 is shorter than the others and floating in order to permit axial movement of the piston in relation to the body, contrasted by the Belleville washers. Moreover, with the appropriate choice of washer and/or spacer height it is possible to vary the preload of the Belleville washers.
[0018] In the start position, which is to say at rest, the piston projects from the body under thrust from the Belleville washers. So when the mould is closed and the two half-valves 12' and 12" are brought together the piston acts thereon, returning into the body contrasted by the Belleville washers. The piston then exerts thrust on the corresponding half-valve, locking it closed on the other half-valve, precisely as required for full and correct suction valve efficiency.
1. Equaliser for the forced closure of a suction valve in die-casting moulds, consisting
of an external body or casing (11), a central thrust piston (16) guided axially on
a guide head (17) and a multiplicity of Belleville washers (18) placed concentrically
between the said piston and body, characterised by the fact that the said Belleville washers (18) are stacked in a common direction,
they are arranged in several groups defined by spacers (21, 21'), where each group
of washers lies axially with one end on a collar (19) on the thrust piston and the
other end on a support washer (20) in the said body.
2. Equaliser in accordance with claim 1, in which the Belleville washers are set out
in threes on each level.
3. Equaliser in accordance with claim 1 and 2 in which the external body or casing (11)
consists of two or more interchangeable segments in order to be able to select body
length depending on the groups of Belleville washers.
4. Equaliser in accordance with the preceding claims, in which the washers and/or spacers
are interchangeable with other of different sizes to vary the preload of the Belleville
washers.
5. Equaliser in accordance with the preceding claims in which the body or casing is associated
with a cover die.
6. Equaliser in accordance with claims 1-5, in which the body or casing consists of a
part of a cover die and the Belleville washers and related spacers are grouped in
the said part of the cover die.
1. Ausgleichseinrichtung für das zwangsweise Verschließen von Absaugventilen in Druckgießformen,
bestehend aus einem äußeren Körper oder Gehäuse (11), einem zentralen Druckkolben
(16), der axial auf einem Führungskopf (17) geführt ist sowie einer Vielzahl von Tellerfedern
(18), die konzentrisch zwi-schen dem genannten Kolben und dem genannten Körper angeordnet
ist, gekennzeichnet durch die Tatsache, dass die genannten Tellerfedern (18) in einer gemeinsamen Richtung
gestapelt sind; sie sind in mehreren Gruppen angeordnet, die durch Distanzstücke (21, 21') gebildet werden, wobei jede Gruppe von Federn axial mit einem
Ende an einem Bund (19) auf dem Druck-kolben und mit dem anderen Ende an einer Auflagescheibe
(20) in dem ge-nannten Körper liegt.
2. Ausgleichseinrichtung nach Anspruch 1, bei der die Tellerfeder in Dreiergrup-pen auf
jeder Ebene eingesetzt sind.
3. Ausgleichseinrichtung nach Anspruch 1 und 2, bei der der äußere Körper oder das Gehäuse
(11) aus zwei oder mehr austauschbaren Segmenten besteht, um zu ermöglichen, die Körperlänge
in Abhängigkeit von den Gruppen der Tellerfeder auszuwählen.
4. Ausgleichseinrichtung nach den vorhergehenden Ansprüchen, bei der die Scheiben und/oder
Abstandsstücke mit anderen verschiedener Größe aus-tauschbar sind, um die Vorspannung
der Tellerfedern abzuwandeln.
5. Ausgleichseinrichtung nach den vorhergehenden Ansprüchen, bei der der Kör-per oder
das Gehäuse mit einer Abdeckform verbunden ist.
6. Ausgleichseinrichtung nach Anspruch 1 bis 5, bei der der Körper oder das Gehäuse aus
einem Teil der Abdeckform besteht und die Tellerfedern und die damit in Beziehung
stehenden Distanzstücke in dem genannten Teil der Abdeckform gruppiert sind.
1. Egaliseur pour la fermeture forcée de clapets d'aspiration dans les moules de coulée
sous pression, comprenant un corps ou un boîtier externe (11), un piston de poussée
central (16) guidé axialement sur une tête de guidage (17) et une multitude de rondelles
Belleville (18) placées concentriquement entre lesdits piston et corps, caractérisé en ce que lesdites rondelles Belleville (18) sont empilées dans une direction commune, et agencées
en plusieurs groupes définis par des espaceurs (21, 21'), chaque groupe de rondelles
étant disposé axialement avec une extrémité sur un collet (19) sur le piston de poussée
et l'autre extrémité sur une rondelle de support (20) dans ledit corps.
2. Egaliseur selon la revendication 1, dans lequel les rondelles Belleville sont agencées
par trois sur chaque niveau.
3. Egaliseur selon la revendication 1 ou 2, dans lequel le corps ou boîtier externe (11)
comprend deux ou plusieurs segments interchangeables afin de pouvoir sélectionner
la longueur de corps selon les groupes de rondelles Belleville.
4. Egaliseur selon l'une quelconque des revendications précédentes, dans lequel les rondelles
et/ou les espaceurs sont interchangeables avec d'autres de différentes tailles dans
le but de varier la charge préalable des rondelles Belleville.
5. Egaliseur selon l'une quelconque des revendications précédentes, dans lequel le corps
ou boîtier est associé à un bloc fixe.
6. Egaliseur selon l'une quelconque des revendications 1 à 5, dans lequel le corps ou
boîtier comprend une partie d'un bloc fixe, et les rondelles Belleville et les espaceurs
correspondants sont groupés dans ladite partie du bloc fixe.