DE102013009055B4 - Tool and process for the production of salt cores for the die casting of metals - Google Patents

Abstract

Tool (100) for producing die cast suitable salt cores (200) by cold wet pressing a salt-liquid mixture,
- With a die (110) and a relatively movable ram (120) defining therebetween a shaping cavity (K), wherein the cavity (K) with at least one venting gap (140, 150) is formed, what about during the pressing process an intended escape of the liquid from the salt-liquid mixture is made possible, and
- With a die (110) surrounding and this relatively movable die ring (130) which limits the cavity (K) in the lateral direction, wherein the die ring (130) during the pressing operation together with the press ram (120) in the pressing direction (F) movable is
in which
between the die (110) and the die ring (130) and / or between the ram (120) and the die ring (130) at least one channel-like vent gap (140, 150) is present, over which an intentional escape of the liquid during the pressing process the venting gap (140, 150) is formed with a gap width (b) between 0.01 mm and 1.00 mm and a gap height (h) between 1.00 mm and 10.00 mm is.

Description

The invention relates to a tool for the production of salt cores for the formation of cavities in die casting of metals.

The invention further relates to a process for the production of salt cores for the formation of cavities during die casting.

Salt cores for the formation of cavities in the die casting of metals are known from the prior art. These salt cores serve to keep the cavities provided in a casting free when filling the casting mold with molten metal. For this, the salt cores must have sufficient mechanical and thermal stability. The salt cores are later released residue-free from the casting, eg. By washing.

For the production of such salt cores various possibilities or procedures are known, which is representative of the patents DE 103 59 547 B3 . DE 10 2006 046 792 A1 . DE 10 2009 015 984 A1 . DE 10 2010 044 287 A1 and DE 10 2013 007 735 A1 is referenced.

The closest prior art is that in the patent WO 98/06561 A2 described filter press with a plurality of press chambers, which are each closed around with a sliding ring and sealed by means of seals.

The invention has for its object to provide a further possibility for the production of salt cores, which does not have at least one associated with the prior art disadvantage or at least only to a reduced extent.

This object is achieved by an inventive tool with the features of claim 1 and by an inventive method with the features of the independent claim 6. Preferred developments and refinements are analogous to both subject invention both from the respective dependent claims and from the following explanations.

The tool according to the invention is used for the production of die cast suitable salt cores by cold wet pressing a salt-liquid mixture. The tool has a die and a relatively movable ram, which delimit between them a shaping cavity, wherein the cavity is formed with at least one breather gap, through which during the pressing operation, d. H. when compressing the salt-liquid mixture in the cavity, an intended escape of the liquid from the salt-liquid mixture is made possible.

According to the invention, it is provided to produce a salt core by compacting a treated salt-liquid mixture, which may be referred to as wet pressing.

According to the invention, it is further provided that the compression of the previously introduced into the cavity salt-liquid mixture is carried out at room temperature, which can be referred to as cold pressing or compaction. In this pressing or compacting the shaping of the salt core takes place, at the same time a large part of the liquid contained in the salt-liquid mixture is pressed out.

In particular, the salt-liquid mixture is a pasty or pasty mixture of a salt material (or a salt mixture) and a liquid (or a liquid mixture). The liquid content of the salt-liquid mixture is between 5 wt .-%. and 40% by weight. The compaction of the salt-liquid mixture takes place in a shaping cavity of the tool according to the invention (mold cavity) by actuating the press ram (and / or optionally also the die). For actuating the press ram, the tool according to the invention is installed in a press or a closing device (or the like). By appropriate design of the cavity, a plurality of salt cores can be produced simultaneously with a tool according to the invention.

In order to enable trouble-free escape of the liquid during wet pressing or compacting of the salt-liquid mixture in the cavity, the cavity of the tool according to the invention is formed with at least one venting gap. A gap extends between at least two cavity forming tool components (see below). The given venting possibility further reduces the internal pressure acting on the cavity during compression. A venting gap thus also serves as a relief gap.

The invention enables a cold manufacturing process for die cast suitable salt cores for the formation of cavities in die casting of metals and in particular in light metal die casting. The cold production is advantageous, among other things, with regard to the equipment required and the energy used, in comparison with the methods known from the prior art. The salt cores produced according to the invention have both good dimensional stability and high mechanical and thermal stability. The The invention is also suitable for mass production because the salt cores can be produced in a constant quality (in particular with regard to dimensional stability and stability) in a short time.

The embodiment of the tool according to the invention provides that the die is surrounded by a relatively movable and ring-shaped die (hereinafter referred to as die ring), which limits the cavity in the lateral direction (ie transversely to the direction of movement or movement axis of the press ram), said die ring during the pressing operation is movable together with the press ram in the pressing direction. It is further provided that at least one channel-like venting gap is formed between the die and the die ring and / or between the press die and the die ring. In this case, distributed over the circumference can be provided a plurality of channel-like ventilation gaps, which are preferably arranged in relevant and / or critical areas.

It is envisaged that the channel-like vent gap has a gap width (transverse to the direction of movement or axis of the punch) between 0.01 mm and 1.00 mm and preferably between 0.03 mm and 0.12 mm. It is further provided that the channel-like venting gap over a gap height (in the direction of movement of the ram) between 1.00 mm and 10.00 mm, and preferably between 2.50 mm and 5.00 mm with a constant gap width, in particular according to the aforementioned sizes , is formed (based on the end position of the press ram).

The tool according to the invention may be formed with at least one Entformungsschräge, as explained in more detail below.

• - Bereitstellen eines erfindungsgemäßen Werkzeugs;
• - Einbringen bzw. Ablegen eines Salz-Flüssigkeit-Gemischs in die Kavität dieses Werkzeugs mit einem Flüssigkeitsanteil zwischen 5 Gew.-% und 40 Gew.-%, wobei das Einbringen insbesondere mit einer exakten Dosierung erfolgt; und
• - Verdichten des Salz-Flüssigkeit-Gemischs durch Betätigen (d. h. kraftbeaufschlagtes Bewegen) des Pressstempels bei Raumtemperatur, wobei die im Salz-Flüssigkeit-Gemisch enthaltene Flüssigkeit durch den oder die kanalartigen Entlüftungsspalte zwischen dem Gesenk und dem Matrizenring und/oder zwischen dem Pressstempel und dem Matrizenring entweichen kann.

The method according to the invention for the production of die cast suitable salt cores comprises at least the following method steps, where further steps and / or substeps not described in further detail can be provided:

• - Providing a tool according to the invention;
• - Introducing or depositing a salt-liquid mixture in the cavity of this tool with a liquid content of between 5 wt .-% and 40 wt .-%, wherein the introduction takes place in particular with a precise dosage; and
• - Compressing the salt-liquid mixture by pressing (ie force-moving) of the press ram at room temperature, wherein the liquid contained in the salt-liquid mixture through the channel or the deaerating gaps between the die and the die ring and / or between the ram and the Can escape template ring.

In this case, it is provided that the tool has a die ring which laterally delimits the cavity (as explained above) which is moved together (ie simultaneously and with the same direction of movement) with the pressing punch in the pressing direction, whereby a sliding movement takes place against the inner wall of the die ring Compressive salt-liquid mixture comes. This sliding movement favors the compression of the salt-liquid mixture (otherwise, the effective frictional forces would be overcome in addition).

The salt-liquid mixture is in particular a pasty or pasty sodium chloride-water mixture. The mean grain size of the sodium chloride grains may be in the range of less than or equal to 2 microns to greater than or equal to 5 mm in normally distributed assumed particle size distribution. Alternatively, it may be a bimodal or multimodal mixture, the size ratio of 1: 2 to 1: 30 (fine powder: coarse powder) and their mixing ratio of 10: 1 to 1: 200 (fine powder: coarse powder) may be. The water content is between 5 wt .-% and 40 wt .-%. Such a pulpy or pasty salt-liquid mixture may also be referred to as a wet salt powder mixture. In a preferred and advantageous manner, the pasty salt-liquid mixture or the sodium chloride-water mixture without additives or additives (such as, for example, sintering aids, binders, fillers, catalysts or the like) comes from. However, such additives may also be provided, such as in the DE 103 59 547 B3 or DE 10 2006 046 792 A1 described.

When removed from the mold, the finished pressed salt core typically has a final contour. The salt core, after removal from the tool in air, d. H. At room temperature, or in a furnace device, for example. At about 100 ° C or above 100 ° C, dried to eliminate any residual moisture contained and to obtain optimal properties for die casting by complete drying. Drying in a furnace or the like is not comparable to a heat treatment for activating a binder or for sintering because of the effect to be achieved and the process parameters (such as temperature, pressure and time). Drying can be done immediately after removal from the tool. Preferably, however, it is provided that the drying takes place shortly before and in particular directly before die casting.

• 1 zeigt ein erfindungsgemäßes Werkzeug in einer schematischen Schnittdarstellung.
• 2 zeigt in einer Detaildarstellung den oberen Entlüftungsspalt am Werkzeug der 1.

The invention will now be described by way of example and not by way of limitation with reference to the figures. The features shown in the figures and / or explained below may, regardless of specific feature combinations, be general features of the invention.

• 1 shows a tool according to the invention in a schematic sectional view.
• 2 shows in a detailed view of the upper venting gap on the tool 1 ,

1 shows schematically and not to scale a tool according to the invention 100 for the production of die cast suitable salt cores 200 ,

The tool 100 is installed in a press or locking device, not shown.

The tool 100 includes a die 110 , which is designed as a fixed lower punch, a punch 120 , which is designed as a movable upper punch, and a Matrizenring 130 which is designed as a movable or flying die. The die 110 and the press stamp 120 between them define a shaping cavity K, to which the die 110 and / or the punch 120 is formed with shaping sections. In the lateral direction (ie transversely to the direction of movement or axis L of the press ram 120 ), the cavity K through the Matrizenring 130 limited.

The tool 100 has an upper venting gap 140 and a lower vent gap 150 on. The upper vent gap 140 extends between the outer peripheral surface of the ram 120 and the inner wall of the die ring 130 , The lower ventilation gap 150 extends between the outer peripheral surface of the die 110 and the inner wall of the die ring 130 , The venting column 140 and 150 are circumferential, in particular with a constant gap, formed.

For the production of a salt core 200 gets into the cavity K of the opened tool 100 , For example, by a metering process, an exact amount of a prepared salt-liquid mixture, which is in particular a pulpy or pasty sodium chloride-water mixture introduced. Subsequently, the salt-liquid mixture in the cavity K in a pressing operation by pressing the press ram 120 compressed at room temperature.

The here on the press stamp 120 applied force and direction of force (the direction of movement of the ram 120 corresponds) is illustrated by the arrow F. The movement axis is with L designated. The force F is generated by an actuator of the press or closing device. The press stamp 120 To do this, grasp the matrix ring 130 a, like in 1 shown. The liquid contained in the salt-liquid mixture is expelled during compression, in particular gaseous by exceeding a critical pressure, and can through the venting column 140 and 150 escape, which is illustrated by bow arrows.

When compacting or pressing the salt-liquid mixture, the Matrizenring 130 along the axis of movement L moves down, which is illustrated by the movement arrows M. Here it comes to the inner wall of the Matrizenrings 130 to a sliding movement against the condensing salt-liquid mixture. This sliding movement prevents sticking and favors the compaction of the salt-liquid mixture (otherwise the effective frictional forces would have to be overcome). The movement of the die ring 130 can be synchronous or asynchronous to the movement of the ram 120 respectively. For actuating the die ring 130 the press or closing device can be designed with a separate actuator. The actuation of the Matrizenrings can be done from above or from below.

2 shows in a detailed view of the upper venting gap 140 , where the punch 120 in end position (UT). The ventilation gap 140 has a gap width b (transverse to the axis of movement L of the press ram 120 ) between 0.01 mm and 1.00 mm, preferably between 0.03 mm and 0.12 mm, and a gap height h (parallel to the movement axis L of the ram 120 ) between 1.00 mm and 10.00 mm, preferably between 2.50 mm and 5.00 mm. The gap width b is constant over the gap height h. The upper vent gap 140 is thus exactly defined, that is, dimensionally accurate. The lower ventilation gap 150 can, based on the end position of the die ring 130 , Which have the same gap dimensions, whereby this is also accurately determined. The venting column 140 and 150 are in particular designed so that, although liquid escape, but a squeezing salt-liquid mixture is prevented.

After the compression or compression of the salt-liquid mixture in the cavity K, the tool 100 by lifting the press ram 120 and by lowering (or possibly lifting) the die ring 130 be opened. To lower the die ring 130 to simplify and damage the prepared salt core 200 to avoid its inner wall with at least one Entformungsschräge 131 be trained as in 2 illustrated. The angle c of the draft angle 131 (relative to the axis of movement L) may be up to 2 ° and is preferably in the range between 0.5 ° and 1.0 °.

After removal of the final contour having salt core 200 This can be dried at room temperature or in a furnace device to eliminate the residual moisture contained.

Claims (8)

Tool (100) for producing die cast suitable salt cores (200) by cold wet pressing a salt-liquid mixture, - With a die (110) and a relatively movable ram (120) defining therebetween a shaping cavity (K), wherein the cavity (K) with at least one venting gap (140, 150) is formed, what about during the pressing process an intended escape of the liquid from the salt-liquid mixture is made possible, and - With a die (110) surrounding and this relatively movable die ring (130) which limits the cavity (K) in the lateral direction, wherein the die ring (130) during the pressing operation together with the press ram (120) in the pressing direction (F) movable is in which between the die (110) and the die ring (130) and / or between the ram (120) and the die ring (130) at least one channel-like ventilation gap (140, 150) is present, over which an intentional escape of the liquid during the pressing process the venting gap (140, 150) is formed with a gap width (b) between 0.01 mm and 1.00 mm and a gap height (h) between 1.00 mm and 10.00 mm is. Tool after Claim 1 , characterized in that between the die (110) and the die ring (130) and / or between the press ram (120) and the die ring (130) distributed over the circumference a plurality of such channel-like venting gaps (140, 150) are provided. Tool (100) according to one of the preceding claims, characterized in that the venting gap (140, 150) has a gap width (b) between 0.03 mm and 0.12 mm. Tool (100) according to one of the preceding claims, characterized in that the venting gap (140, 150) has a gap height (h) between 2.50 mm and 5.00 mm with a constant gap width (b). Tool (100) according to one of the preceding claims, characterized in that it is formed with at least one Entformungsschräge (131). A method of making die castable cores (200) comprising the steps of: - providing a tool (100) according to any one of the preceding Claims 1 to 5 ; - Introducing a salt-liquid mixture in the cavity (K) with a liquid content of between 5 wt .-% and 40 wt .-%; and - compacting the salt-liquid mixture at room temperature by actuating the ram (120), the liquid contained through the vents (140, 150) between the die (110) and the die ring (130) and / or between the vents Press die (120) and the die ring (130) can escape, wherein the cavity (K) laterally limiting die ring (130) is moved together with the press ram (120) in the pressing direction (F), whereby it on the inner wall of the die ring (130 ) comes to a sliding movement relative to the condensing salt-liquid mixture. Method according to Claim 6 , characterized in that it is the salt-liquid mixture is a pulpy or pasty sodium chloride-water mixture. Method according to Claim 6 or 7 , characterized in that the finished pressed salt core (200) is dried after removal from the tool (100) at room temperature or in a furnace device.

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