EP1488872B1 - Device for the manufacture of casting moulds - Google Patents

Abstract

To produce a sand mold, for casting, the sand is blown into a chamber zone containing a model through an opening (122), with slits at least in the limit plate to allow the air to escape. At least one plate (1) is of a wear-resistant material e.g. containing >=1.0 wt.% carbon and >=8.0 wt.% chrome. The material also contains manganese (Mn), molybdenum (Mo), tungsten (W) and vanadium (V) as the main alloy constituents. A number of curved slits (2) are located at the air escape zones. The plate has a sandwich structure with fasteners (123) with a carrier plate of construction steel, and a hard layer plate (12) of a wear-resistant material towards the interior.

Description

The invention relates to a boundary plate for a chamber space for creating a mold piece at least one casting mold, wherein processed molding sand for forming pieces with compressed air injected into the chamber space enclosing a model and the air is discharged through slots in at least one of the boundary plates of the chamber space.

Castings are increasingly being used in modern technology because they have high product quality and economic efficiency, in particular in mass production, due to the improved manufacturing process, the increased quality of the cast metal and the possibility of a largely automated production technology.

An economic mold production is of particular importance, because it must on the one hand have a special profile stability, but also a starting point in the introduction of liquid metal in order to ensure the best casting surfaces. On the other hand, in automated operation, a targeted introduction of molding material in a mold space around the model for mold production is of importance in order to achieve uniformly high piece quality in a casting series.

Casting molds can be produced in the box and boxless process, wherein in the former two boxes each filled with a model half with foundry sand and positioned congruent to one another after pouring the sand and made ready for casting. Special equipment has been developed for a boxless casting production. In principle, a formation of a chamber space bounded by plates takes place, wherein two opposite plates carry model parts and are movable relative to one another. At least one further plate has a generally gap-shaped wider opening, through which molding sand can be injected, wherein for a discharge of the injection air from the chamber chamber narrow slits in the (n) other plate (s) are provided.

For mold production takes place in the case-less process after filling the chamber space with foundry sand in Einblaseverfahren a mutual approach of the model plates and thus a further compacting of the sand, after which a two-sided fashion structure exhibiting mold from the device can be deployed and provided. Another mold piece is tightly fitted with the counter model structure respectively to the prefabricated one, thereby forming a plurality of similar mold cavities in a mold string, which can be filled with liquid metal for series production of castings.

The processed molding sand is blown in the boxless molding production process usually with about 2 to 3 bar pressure having air into the chambers. Basically, a chamber consists of two side plates, two model plates, a bottom plate and a top or cover plate. In most cases, the side plates and the top plate are provided with Luftaustragsmitteln optionally in the form of annular slots, which usually has the upper plate and a gap-shaped opening for blowing the molding sand.

The molding sand has an abrasive effect on the boundary plates of the chamber space, so that these, also called chamber plates, are made of case-hardened steel plates according to the prior art. The annular slots for the air discharge in the designated chamber plates are consistently created such that in prefabricated holes of the case-hardened steel plates are pressed with a thickness of 15 mm to 30 mm specially shaped nozzle pieces whose head has a distance to the bore wall.

Such a case hardened steel limiting plate for a chamber space, which chamber plate has a variety of holes equipped with nozzles for creating the Luftaustragsschlitze, may well have the desired functions in a machine for molding production, but has the disadvantages of a low life and a complex production.

The invention is now the goal of creating a boundary plate for a chamber chamber of the type mentioned, which plate can be produced economically, has a higher wear resistance and durability and has the required performance properties.

This object is achieved in a generic chamber chamber according to the invention, on the one hand, characterized in that at least one provided for the air discharge boundary plate or chamber plate made of a wear-resistant material, for example containing in wt .-% more than 1.0 wt .-% carbon (C) and more than 8.0% by weight of chromium (Cr), optionally further comprising proportions of manganese (Mn), molybdenum (Mo), tungsten (W) and vanadium (V) as main alloying elements, and in the region (s) ) has a plurality of curved slots for the air discharge.

The advantages achieved by the invention are essentially to be seen in the fact that in a wear-resistant planar material, which may optionally be quenched thermally treated, introduced with modern technologies, such as laser electron beam and the like method, curved slots in the erfoderlichen dimension can be. A wear-resistant hard material increases the life of a plate disproportionately only with moderately higher material costs. In this case, according to the invention, a curvature of the slots has been found to be essential, because thereby a resonance excitation to the vibration of the webs which can lead to a web break is prevented.

The object of the invention is also achieved in a chamber chamber of the type mentioned in that at least one provided for the air discharge boundary plate or chamber plate in sandwich construction with a support plate and a facing the interior of hard-wearing material formed hard layer plate is formed and the hard layer plate a Having a plurality of curved slots, which correspond to the air discharge means of the support plate.

The advantages achieved by this embodiment of the invention are in particular that due to the sandwich design only the most highly stressed on abrasion thin parts of the chamber plate is made of wear-resistant, usually medium to high alloy steel and a stable support member made of tough structural steel. It may also be advantageous if the Luftaustragsschlitze in a thin wear-resistant sheet, for example by means of laser beam, are introduced, because this, due to geometric reasons, gives advantages regarding a machining accuracy.

At most, the individual slots are designed according to the invention curved, so that no straight webs are formed, which can arrive at a stimulation during operation in resonant vibrations, which represent an increased risk of breakage due to a general given material brittleness of highly wear-resistant materials.

Of particular importance for avoiding a slot system resonance, but also for trouble-free operation in continuous operation while avoiding blockages, it may be favorable in one embodiment of the invention that provided for a Luftaustrag curved slots in the chamber plate or in the hard-layer plate a shape of a preferably round, interrupted by webs annular slot having a width of 0.4 to 0.6 mm.

In a sandwich construction of a boundary plate according to the invention, it may be advantageous if the support plate is made of structural steel, for example a material 52.3 and has vent holes, that the hard-layer plate, for example, on a material No. 1.2601 steel-iron list, has a thickness of up to 3.8 mm and has interrupted ring slots whose hole pattern or outer diameter and their geometric arrangement with the vent holes in the support plate match and that the support plate and the hard-coated plate is fitted to the openings according to fit.

The advantage lies in such an embodiment of the chamber plate, as was found, on the one hand in an economical or cost-effective production and processing, in particular, the support plate has low material costs, on the other hand outstanding performance characteristics are achieved with high plate stability.

Further, in a favorable embodiment of the invention, the joining of the sandwich panels by adhesion, for example by means of a commercially available metal adhesive is created, the manufacturing technology can be further simplified and the support and the damping of the hard-coated plate can be improved.

To increase the service life of the boundary plates in hard operation with quartz sands can be provided that this or the hard layer of a sandwich plate is formed from a tool steel and has a thermal wear by highest wear resistance and toughness-containing structure.

• Fig.1 eine als Ober- oder Deckplatte ausgeformte erfindungsgemäße Begrenzungsplatte eines Kammerraumes
• Fig. 2 einen Querschnitt durch eine Sandwichplatte im Bereich einer Entlüftungsbohrung
• Fig. 3 eine Draufsicht auf einen Ringschlitz in einer Kammerplatte

The invention will be explained in more detail on the basis of drawings that merely represent one embodiment. It shows:

• Fig.1 a shaped as top or top plate inventive boundary plate of a chamber space
• Fig. 2 a cross section through a sandwich plate in the region of a vent hole
• Fig. 3 a plan view of a ring slot in a chamber plate

Fig. 1 shows in top view of the chamber interior a top or cover plate 1. In a homogeneous or sandwiched plate 12 is a plurality of interrupted ring slots 2 introduced as discharge for a conveying gas, which is arranged around a gap-shaped opening 122 for blowing molding sand by means of conveying gas. To fix the plate 1 fasteners 123 are provided.

In Fig. 2 is a cross-sectional view of a sandwich plate, consisting of a support plate 11 and a hard-layer plate 12 in section, shown in the region of a Luftaustragsmittels. A carrier plate 11, which has vent bores 111, is connected in a planar manner to a hard-layer plate 12 with a thickness 121, in that annular slots 2 are positioned in the hard-layer plate 12 within the bore 111 of the carrier plate 11.

Fig. 3 shows a slot image and a plan view from the chamber interior to a ring slot 2 in a Begrenzungsplatte1. A ring slot 2 with an outer diameter 23 has a slot width 22 and webs with a width 21. In the illustrated embodiment with three webs 21, these land areas must absorb shear forces due to a higher pressure in the chamber space and the annular slot inner surface. Resonant vibrations of a part are not given during operation.

Claims (6)

1. Boundary plate for a chamber space for establishing a piece of mould of at least one casting mould, wherein prepared moulding sand is injected for forming a piece of mould by pressurised air into a chamber space, which encloses a model, and air is evacuated through slots in at least one of the boundary plates of said chamber space, characterised in that at least one boundary plate or chamber plate (1), which is provided for evacuating air, is formed of a wear resistant material and comprises a plurality of curved slots (2) in the region(s) provided for the evacuation of air.
2. Boundary plate for a chamber space for establishing a piece of mould of at least one casting mould, wherein prepared moulding sand is injected for forming a piece of mould by pressurised air into a chamber space, which encloses a model, and air is evacuated through slots in at least one of the boundary plates or chamber plates of said chamber space, characterised in that at least one boundary plate or chamber plate (1), which is provided for evacuating air, is formed in a sandwich construction comprising a carrier plate (11) and a hard layer plate (12) of wear resistant material and facing the inner space, wherein said hard layer plate (12) comprises a plurality of curved slots (2) corresponding to the air evacuation means (111) of said carrier plate (11).
3. Boundary plate according to claim 1 or 2, characterised in that the curved slots (2), which are provided for evacuating air, and which are either in the chamber plate (1) or in the hard layer plate (12) have the shape of a preferably round annular slot (R) interrupted by straps (21), which has a width (21) of 0.4 to 0.6 mm.
4. Boundary plate according to claim 2, characterised in that the carrier plate (11) is produced of structural steel, for example of a material 52,3, and has evacuating boreholes (111), that the hard layer plate (12) is, for example, of a material No. 1.2601 according to the Stahl-Eisen-Liste, has a thickness (121) of up to 3.8 mm and an interrupted annular slot (2), the pinhole image or outer diameter (23) of which and the geometrical arrangement of which coincide with those of the evacuating boreholes (111) in the carrier plate (11), and that the carrier plate (11) and the hard layer plate (12) are joint in an accurately fitting manner in accordance with the openings (2, 111).
5. Boundary plate according to claim 2 or 3, characterised in that joining the sandwich plates (11, 12) is made by cementing, for example by means of a commercial metal bonding agent.
6. Boundary plate according to any of claims 1 to 4, characterised in that said boundary plate (1) or said hard layer plate (12) is are formed of a tool steel and, by thermally annealing, has a structure of maximum wear resistance and toughness.

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