FI91836C - A method of providing a release agent layer in a mold - Google Patents

Description

91836

A method of providing a release agent layer in a mold 5

The invention relates to a method for providing a release agent layer in a mold as set out in the preamble of appended claim 1.

10 In casting technology, it is particularly difficult to remove large pieces from the mold due to the large adhesion area. As a result, there are several types of release agents in use to facilitate removal. Prior to casting, the release liner is applied to the mold on the 15 surfaces that come into contact with the body to be cast.

For example, release agents have been sprayed onto the surface of the mold. Such a technique is known, for example, from U.S. Pat. No. 3,931,381, in which a mixture of wax and solvent is used as the release agent 20, which is first injected into the mold and then dried.

Other application methods in which the release agent is applied, e.g., by injection into a mold, are disclosed in U.S. Patent 4,491,607, GB Patent 1,572,403, GB Patent. 25 1,213,940, GB Patent 1,370,023 and GB Patent Application Publication 2,081,637.

These methods do not provide a uniform layer of release agent, especially in the case of a mold with a plurality of alternating recesses and ridges transverse to the pSS plane of the mold.

This results in the casting sticking in places to the mold or to the poor quality of the casting surface.

35 Finnish patent application 894830 discloses a method in which there is a thin layer of release agent on the surface of a liquid, and the mold is immersed in the liquid from above. In this case, the recesses and protrusions on the surface of the mold 2 91836 against the casting are evenly covered with a thin layer of release agent. The release agent can then be, for example, a lighter-than-liquid fatty acid in the molten state on the surface of the liquid, which is stagnant on the surface of the mold when the mold is lifted upwards. A mold is a rigid structure that is lowered into a liquid so that its main plane is parallel to the liquid surface. In this case, the problem has become that, due to the diversity of the mold surface, air pockets tend to remain there despite the fact that air is allowed to escape, e.g. When immersed inside the mold, the distributed air, in turn, impairs the spread of the release agent layer on the mold surface and reduces the quality of the casting.

The object of the invention is to present an improvement e.m. technology and eliminate e.m. ills. In order to achieve the purpose of TamS, the method according to the invention is mainly characterized by what is set forth in the characterizing part of the appended claim 1. When the mold is immersed in the liquid in a curved manner so that its various points gradually come into contact with the release agent 25 in succession, it is time for the air to exit at different points in the mold.

In addition, the implementation of the method has several alternatives, which are described in the appended claims 30 2-5 as well as in the description below.

The invention will now be described in more detail with reference to the accompanying drawings, in which Figure 1 shows an alternative embodiment of the method according to the invention,

II

3 91836 Fig. 2 shows a second embodiment of the method according to the invention Fig. 3 shows a third embodiment of the method according to the invention, Fig. 4 shows a mold treated by the method 11a during a casting step on a larger scale, Fig. 5 illustrates detachment of a casting from a mold according to the invention. is an example of a product which can be produced by a mold treated by the method according to the invention.

Figure 1 below shows the main features of the method according to the invention. The container has a liquid 3, the surface of which has a layer 1 of a lower-density release agent in a liquid state.

A mold having a dimension mainly in the direction of the two 25 dimensions, i.e. a relatively wide area and a mold, is immersed in the liquid so that the release agent moves from the layer 1 to the mold surface, uniformly covering the alternating recesses and protrusions in the mold e.m. against the plane formed by the two dimensions 30 in perpendicular directions.

.. During immersion, the end plane of the mold is curved, in which case the immersion is carried out in such a way that, in the direction of curvature (arrow A), successive points of the mold come into contact with the liquid 3 in succession. In Fig. 1 35 the immersion is performed so that the mold is initially in contact with the liquid at one of its edges 2a,. after which the remainder is gradually lowered into the liquid, as illustrated by the broken lines.

91836 _______ - · i— 4

Figure 2 shows another alternative, in which the mold is initially in contact with the liquid from the central part 2b, after which both parts between the central part and the edges 2a and 2c 5 are gradually lowered into the liquid, whereby successive areas from the central part to the edge come into contact with the liquid.

In the previous examples, the mold is in the final stage 10 straight parallel to the plane of the liquid surface. According to the alternative of Figure 3, the release agent can also be introduced into the mold so that the successive parts of the mold in the direction of curvature are alternately in contact with the liquid, i.e. only one area at a time is in the liquid. The curved mold is then covered in such a way that the release agent is always transferred from the release agent layer 1 to the part which is in the liquid. In Fig. 3, this is realized in practice so that the upper surface of the liquid has a pydrivS drum 5, on the circumference of which a mold is attached. As the drum rotates, the areas on its circumference at successive points M alternately come into contact with the liquid 3. The drum 5 can move forward as it rotates (arrow B), whereby the mold always comes into contact with different areas of the liquid surface, or the rotor 25 is in place, in which case the release agent must be Riitta and its surface tension low enough the mold is in contact with the liquid surface.

30 ·. Figure 4 shows a part of the mold as a cross-leak after immersion in liquid. The release agent 1 has been distributed in a thin layer on the surface of the mold 2 (the thickness of the layer is greatly exaggerated for the sake of clarity 35). As can be seen in Figure 4, the mold is relatively thin-walled, with its walls following the shapes of the protrusions and recesses of the mold. Such a mold, which can be made of, for example, a sufficiently heat-stable list and a plastic of flexible material, is easy to bend even with very small radii of curvature. On a smooth surface of the mold with a release agent layer, a casting material in a fluid state is poured, which solidifies into the mold. Thereafter, by heating the mold 2, the release agent layer between the casting and the mold is melted, whereby the casting 4 can be easily removed from the mold (Fig. 5). In addition, it can be mentioned that the flexibility of the mold 2 is also advantageous here, since the mold can be bent off the casting 4 so that its successive parts are detached from the casting in succession.

Figure 6 shows a casting 4 made of a mold treated by the method 15 according to the invention. This is a honeycomb structure with hexagonal openings passing through the plane of the cell. The corresponding mold 2 is implemented in such a way that the recesses against its main plane form a network of 20 interconnected hexagons, which forms a mold cavity into which the casting material is applied as shown in Fig. 4.

The invention can also be used to make castings of other shapes. In addition, the invention can: use all molds that can be bent from a straight shape to a curved shape and back straight. Likewise, the invention is not limited to the use of a particular release agent, but all release agents that can be applied to the surface of the mold by immersing the mold in a liquid can be used as the release agent 30. The release agent may then be a melting agent at a suitable temperature, such as stearic acid (melting point about 70 ° C), which is on the surface of a liquid with a density 35 heavier than the melting point, such as water. The release agent can also cause release due to its other physical properties.

Claims (6)

91836 A method for providing a release agent layer 5 in a mold having alternating recesses and protrusions transverse to the end plane of the mold, the method comprising immersing the mold (2) in a liquid (3) having a lower density release layer (1) on its surface in a known liquid state. that during immersion the end plane of the mold is curved, whereby the immersion is performed in such a way that successive points of the mold come into contact with the liquid (3) one after the other in the direction of curvature. Method according to Claim 1, characterized in that the curved mold (2) is initially in contact with the liquid (3) at one point, after which the remainder is lowered into the liquid so that the mold is finally parallel to the surface of the liquid (3). 20 Method according to Claim 2, characterized in that the mold is initially in contact with the liquid (3) at its edge (2a), after which the remainder is gradually lowered into the liquid (3). 25 Method according to claim 2, characterized in that the mold is initially in contact with the liquid from the central part (2b), after which both parts 30 between the central part (2b) and the edges (2a, 2c) are gradually lowered into the liquid (3). Method according to Claim 1, characterized in that the curved probe (2) is turned in the liquid (3) in such a way that, in the direction of curvature, 35 successive parts of the mold (2) are in alternate contact with the liquid (3). 91836 A method according to claim 5, characterized in that the mold (2) is fixed to a curved surface, such as the surface of a groove (5), and the body 5 in which said surface is located is rotated when the mold (2) is in contact with the liquid (3). 91836 Patentkrav;