EP1181998A2

EP1181998A2 - Equaliser for forced closure of suction valves in die-casting moulds

Info

Publication number: EP1181998A2
Application number: EP01830543A
Authority: EP
Inventors: designation of the inventor has not yet been filed The
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-08-24
Filing date: 2001-08-16
Publication date: 2002-02-27
Anticipated expiration: 2021-08-16
Also published as: EP1181998A3; DE60124992T2; IT250560Y1; DE60124992D1; ITBS20000060V0; EP1181998B1; ATE347458T1; ITBS20000060U1

Abstract

The invention concerns an equaliser for the forced closure of a suction valve in die-casting moulds. It consists 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 piston and body. The Belleville washers (18') are set out in groups on several parallel levels defined by spacers, and each group of Belleville washers lies axially with one part on a collar (19) around the thrust piston and the other part on a support washer (20) in the said body. <IMAGE>

Description

This invention concerns an equaliser device to aid closure of a suction valve for the discharge of air and gas from die-casting moulds.

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.

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.

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.

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.

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.

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.

These aims are achieved, in the invention, with an equaliser to be associated with a suction valve in die-casting moulds, in which the Belleville washers are set out in groups of three on several parallel levels defined by spacers and in which each group or trio of Belleville washers lies axially with one part on a collar around a thrust piston and the other against a support washer.

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.

In these drawings the equaliser is shown globally with 11 and associated with a suction valve 12 applied to a die-casting mould 13.

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.

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.

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.

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.

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.

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.

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.

Lastly, it should be noted that the equaliser may also be made without the external casing with guided spacers and piston, which is to say, incorporated into the mould in various ways.

Claims

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 set out in groups on several parallel levels defined by spacers where each group of Belleville washers lies axially with one part on a collar (19) around the thrust piston and the other part on a support washer (20) in the said body.
Equaliser in accordance with claim 1 in which the Belleville washers are set out in threes on each level.
Equaliser in accordance with claims 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.
Equaliser in accordance with the preceding claims in which the washers and/or spacers are interchangeable with others of different sizes to vary the preload of the Belleville washers.
Equaliser in accordance with the preceding claims in which the body or casing is associated with a cover die.
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.