EP0919344B1 - Die , in particular for pressing roof tiles - Google Patents

Abstract

The forming surfaces of the top (2) and bottom (4) halves of the die consist of silicon carbide.

Description

The invention relates to a mold, in particular for pressing of roof tiles, with the characteristics of the generic term of claim 1.

Molds for roof tiles are available in different designs known. The shaping surfaces of conventional molds are made either made of plaster or chrome-nickel steel.

Gypsum molds have an excellent peeling behavior from the gypsum after pressing. Leave plaster molds recover easily and inexpensively after wear. The main disadvantage of plaster molds is the heavy wear. The abrasive load on the shaping Areas during the molding process lead to minimal downtimes of a maximum of 2000 pressings, after which a renewal of the Plaster form is essential. Roof tile presses usually work with stroke rates of 5 to 30 pressings per minute. Consequently, when using plaster molds, the otherwise continuous process of roof tile pressing on average all be interrupted for two hours because of a change in shape, Efficiency of the overall system lowers. The need for permanent manufacture and supply of plaster molds and the mechanical and human effort required for this represent a significant cost factor in the manufacture of Roof tiles with plaster molds.

In principle, roof tile shapes made of chrome-nickel steel allow long service lives in the order of 1 million Pressing until reprocessing or renewal of the Mold. The steel molds are much heavier and more expensive as plaster molds. Furthermore, the quality that can be achieved in the long term the pressed roof tile moldings significantly worse than in pressing with plaster molds. This is particularly true of one "Polishing effect" attributable to which after long use of the steel molds at crucial points in the shaping Surface occurs and leads to undesirable pressing errors. This Pressing errors have a greater impact, the smoother it is relevant shaping surface is made of steel. Based on these Quality losses are currently predominant in Germany Plaster molds used for the production of roof tiles.

The release of the molded part from the mold is done with steel molds usually either by brushing with oil or by Electroshock supports to stick the sound to the prevent shaping surfaces and thus the risk of Tearing or damaging the moldings when opening the Avoid form. WO-A-98/43793 represents such a mold and is considered the closest prior art.

From DE-OS 19 25 936 is the upper shape of a roof tile mold known, the molded surface of silicon carbide consists. So far it has not succeeded in good releasing ability and high stability of the mold, high quality of the Compression and low cost of the mold in one Realize construction at the same time.

It is the technical problem of the invention, a mold to create especially for pressing roof tiles, which combines the mentioned properties.

This object is solved by claim 1. Advantageous configurations the invention are specified in the subclaims.

The silicon infiltrated silicon carbide used according to the invention (SiSiC) is initially made from the raw materials Silicon powder, silicon carbide powder and graphite or carbon powder mixed in the usual mixing ratio and in shaped a known ceramic manufacturing process. hereby is the creation of complex, form-bound surfaces made possible in a simple way.

Silicon infiltrated silicon carbide (SiSiC), has an excellent electrical conductivity, which is a particularly light and injury-free detachment of the moldings by electric shock allows. This is achieved in that the in itself known silicon infiltration with regard to an optimized electrical conductivity during the manufacturing process is controlled. The optimized electrical conductivity leads for an optimal detachment of the moldings from the mold Electric shock effect.

After shaping and subsequent drying the one present as a block or as a number of sections Shaped body to create the upper and / or lower mold in solidifies a burning process and receives high mechanical Strength and extremely high abrasion resistance.

The trained as blocks or joined sections Shaped bodies are preferably placed on their backing on support plates, which are advantageously made of steel, releasably attached. It can be between these and the back of the block or sections from the silicon infiltrated SiC material an elastic / plastic Intermediate layer can be arranged in a Execution advantageously consists of Teflon and a thickness of 1 can have up to 2 mm, in particular 1.4 mm.

The invention is based on schematic drawings explained in more detail with further details.

Fig. 1 der aus

eine Preßform gemäß einer ersten Ausführung Erfindung mit je einem massiven Formkörper siliziumimfiltrierten SiC-Material für eine Oberform und eine Unterform;

Fig. 2

eine Variante mit je einem mittels eines Füllmaterials ausgefüllten Hohlgußkörper als Formkörper aus siliziuminfiltrierten SiC-Material;

Fig. 3

eine zweite Ausführung einer Preßform gemäß der Erfindung, bei der die Formkörper von Oberform und Unterform aus Teilstücken aus dem siliziuminfiltrierten SiC-Material zusammengesetzt sind, und

Fig. 4

eine Variante der Fig. 3, bei der die Teil-Stücke jeweils aus mit einem Füllmaterial ausgefüllten Hohlgußkörpern bestehen.

Show it:

Fig. 1 from

a mold according to a first embodiment of the invention, each with a solid molded body silicon-infiltrated SiC material for an upper mold and a lower mold;

Fig. 2

a variant with a hollow cast body filled with a filler material as a molded body made of silicon-infiltrated SiC material;

Fig. 3

a second embodiment of a press mold according to the invention, in which the moldings of the upper mold and lower mold are composed of sections from the silicon-infiltrated SiC material, and

Fig. 4

a variant of FIG. 3, in which the partial pieces each consist of hollow castings filled with a filling material.

In the figures are for the same or equivalent parts the same reference numerals are used.

All versions have in common that the mold is a total with the reference number 2 designated upper shape and an overall has the sub-shape designated by the reference number 4.

1 and 2 show a first embodiment of a press mold according to the invention in two variants.

In the variant according to FIG. 1, the upper mold 2 has one a steel plate 20 by means of strips 21 over inclined surfaces 23 on the last held molded body 22, on the lower mold 4 and thus the mold cavity facing the bottom shaping surfaces 25 corresponding to the interior or Outer contour of a roof tile are formed. The plans Back 26 of the molded body is interposed with one elastic Teflon layer 27 of a thickness of 1.4 mm on the plan bottom 28 of the steel plate 20. On both sides Shaped body 22 beveled corresponding to the inclined surfaces 23 Surfaces 29, so that a dovetail-shaped holder for the molded body 22 is formed on the steel plate 20.

Similarly, the lower mold 4 has a steel plate 40 attached to it Last 41 with inclined surfaces 43 which the molded body 42 over correspondingly bevelled surfaces 49 against the flat top 48 of the steel plate 40 with the interposition of one Hold Teflon layer 47 corresponding to Teflon layer 27. On the molded body 42 has the side facing the upper mold 2 shaping surfaces 45.

1 and 2, the shaped bodies 22, 42 solid, but have the following difference:

In the embodiment according to FIG. 1, the molded body is continuous made of a silicon infiltrated silicon carbide material (SiSiC), whose silicon infiltration is controlled so that optimal electrical conductivity is achieved.

In the embodiment according to FIG. 2, the solid molded bodies are made 22, 42 each of a hollow cast body with an outer layer 220, 420 made of the silicon-filtered silicon carbide material and a filling 221, 421 made of a filling material, such as a carrier mass for resistance heating (not shown). The filling material is, for example, one with water binding chamotte or SiC mortar or a permanently elastic, self-binding plastic casting.

Otherwise, the parts of the upper mold and the lower mold are identical with those of Fig. 1 and therefore not again described.

The second embodiment according to FIGS. 3 and 4 differs is characterized in that the molded body 22, 42 with the shape Surfaces 25, 45 are not designed as massive blocks, but of three sections 230, 231, 232 and 430, 431, 432 are formed. Each on the outside of the molded body 230, 232 and 430, 432 are in turn the inclined surfaces 28 or 48 for mounting by means of the inclined surfaces 23, 43 of the Last 21, 41 provided. The sections of each molded body 22, 42 are at their parting lines 233, 234; 433, 434 either glued using an adhesive that is so soft in the warmth is that a detachment of the sections of the molded body from each other is possible, or at the parting lines 233, 234; 433, 434 adjacent sides are smooth to match trained, for example by grinding or lapping, so that the sections after joining them at their parting lines 233, 234 and 433, 434 by the natural cohesive forces stick together.

In the variant according to FIG. 4, the sections are 230, 231, 232 of the molded body 22 or the sections 430, 431, 432 of the molded body 42 as a hollow cast body with an outer skin 2300, 2310, 2320 or 4300, 4310, 4320 made of silicon infiltrated silicon carbide material and a filling 2301, 2311, 2321 or 4301, 4311, 4321 made of a filling material. As well as 3, the sections adhere to the Parting lines 233, 234 and 433, 434 to each other by gluing or due to the fact that the Surfaces generated cohesive forces.

In all of the exemplary embodiments, the strips 21, 41 by screws 6, 7 indicated in FIG. 3 or in another Fastened in one piece or with the steel plates 20, 40 his. The strips can surround the moldings 22, 42 on all sides.

The shaped bodies 22, 42 can have open pores with such a pore size and such a pore shape that A fluid such as air or water from the mold cavity through the pores can be sucked out. You can do this in the Steel plates 20, 40 corresponding extraction channels (not shown) are provided, which are connected to a vacuum source can be (not shown).

The in the above description, the claims and the Features disclosed can be drawn individually as well in any combination for realizing the invention in their various configurations.

Claims (14)

1. A press mould, more particularly for pressing roof tiles, comprising a top mould (2) and a bottom mould (4), characterised in that the shaping surfaces (25, 45) of the top and bottom moulds consist of silicon-infiltrated silicon carbide (SiSiC).
2. A press mould according to claim 1, characterised in that the silicon infiltration into the silicon carbide is controlled so as to optimise the electrical conductivity of the shaping material.
3. A press mould according to claim 1 or 2, characterised in that the shaping surfaces (25, 45) for the top mould (2) and/or the bottom mould (4) respectively are formed at the front of a unitary block of the silicon-infiltrated silicon carbide facing the mould cavity.
4. A press mould according to any one of claims 1 to 3, characterised in that the shaping surfaces (25, 45) for the top mould (2) and/or the bottom mould (4) respectively are formed at the front sides, facing the mould cavity, of individually exchangeable sections (230, 231, 232, 430, 431, 442) of the silicon-infiltrated silicon carbide which are adapted to be attached to one another in the associated mould.
5. A press mould according to claim 3, characterised in that a plastically or elastically deformable intermediate layer (27, 47) is disposed between the back of the block and the carrier plate (20, 40).
6. A press mould according to claim 5, characterised in that the intermediate layer (27, 47) is a plastic film, more particularly a Teflon film of a thickness between 1 and 2 mm, preferably 1.4 mm.
7. A press mould according to any one of claims 3 to 6, characterised in that the sides (29, 49) of the block or of the outer sections diverge dovetailfashion and in that ledges (21, 41) having appropriately bevelled sides are fixed on the carrier plate (20, 40) on both sides of the block and the outer sections.
8. A press mould according to any one of claims 3 to 7, characterised in that the block (22, 42) or the sections (230, 231, 232 etc) are made as hollow bodies by hollow casting.
9. A press mould according to claim 8, characterised in that the cavities of the hollow bodies are filled with a dimensionally stable material (221, 421, 2301, 4301, etc).
10. A press mould according to claim 9, characterised in that the dimensionally stable material serves as a carrier material for resistance heating means.
11. A press mould according to any one of claims 1 to 10, characterised in that substantial zones of the shaping surfaces are roughened.
12. A press mould according to any one of claims 1 to 11, characterised in that the silicon-infiltrated silicon carbide material of the shaping surfaces has a porosity adapted to the respective clay moisture content.
13. A press mould according to claim 12, characterised in that the porosity is between 0 and 60%, but up to 80% where failure grains are used, the porosity being limited substantially by the remaining strength of the matrix.
14. A press mould according to claim 13, characterised in that the pores of the silicon-infiltrated silicon carbide material of the block or of the sections of the top mould (2) and/or of the bottom mould (4) are open so that a fluid, such as air and/or water, can flow therethrough.

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