DE1508749A1 - Process and device for making molds - Google Patents

Description

PATENT LAWYERS

dr. ing. H. NEGENDANK · dipl-iko. H.IIAUCK dipl.phys. W. SCHMITZ

HAMBURO-MUNICH ADDITIONAL ADDRESS: H AMBURG 36 NEW WALL Il

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Hamburg, June 9, 1969

Method and device for the production of casting molds

The invention te extends to the production of molds by pressing in molding boxes, which during the pressing process free, i.e. not fastened in the pressing direction. This process ensures uniform compaction of the molding sand and better utilization of the pressing force achieved. According to the current state of the art, the following compression molding processes are known:

1. Shapes in molding boxes from above. Here, the molding box and model are immobile. The main disadvantage of this Procedure is the much smaller density of the shape at the bottom of the model. It is much lower than on upper edge of the mold just below the ram. Of the

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The reason for this / the friction between the grains of sand, with part of the pressing force acting not on the molding sand but on the molding box.

2 » Shapes in molding boxes from below. In this procedure

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the molding box is also immobile as in the previous one, but the model moves upwards. The compression is basically the same as with press molding from above, only here the molding sand is densest immediately next to the Iodell. The unevenness of the compression is retained. This fact is particularly unfavorable in tier molding, in which several molding boxes are stacked on top of one another, since one side of the mold is insufficiently compacted. In order to better compact the upper side, higher pressures and molding sand mixtures with less friction between the grains must be used, which is associated with higher costs.

The disadvantages of compression molding from above and below result in a limitation in their application possibilities for higher molds.

3. Forms with additional pressing on the opposite side. Here the molding box is also immobile. First, from above, to - in order to reduce the difference in the compression - coined from the opposite side with additional force. This method has qualitative advantages over the other two methods; However, in order to equalize the densities on both sides , the re-pressing must be carried out with the original force. The result is twice as much energy consumption, increased cost and complication of the molding machine, all disadvantages that 009813/0392 -3-

make this process practically disadvantageous, which is why it has not found wide application.

The object of the invention is to create a pressing process which has the same density on both sides of the mold results in the most effective utilization of the pressing force. According to the invention, the problem posed is achieved as follows:

The molding box is not fixed, but can move in an axial direction, so that the pressure on one side generates the same amount of counter pressure on the other side.

An example of molding in molding boxes according to the invention Solution is shown in Fig. 1. The model 4 is on the immovable model plate with the protrusion 7 attached. The molding box 3 with the filling frames 2 and 9 can move in the axial direction with respect to the Lodell plate with the projection 7 and the ram 1, guided by the centering pins 5j move freely. The height the filling frame 2 and 9 is in view of the required stroke for compacting the molding sand from the relevant Side selected and corresponds to the height 7 of the projection of the model plate. Before filling with molding sand, the

Molding box with the filling frames 9 and 2 from the ejector 8 brought to the upper position (Fig. 1a) and with the catch 6 or the spring 10, which is a small exert axial counteraction, determined in this position. When the ram 1 starts pressing, will

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due to the lateral force caused and the friction between the molding sand and the molding box, part of the pressing force is transferred to the molding box, so that the effect of the adjustable catch 6 or spring 10 is overcome and the molding box sinks downwards. Here, the entire pressing force originating from the ram is transmitted only via the molding sand to the model 4 and the projection of the model plate 7, ie the pressing pressure on both sides of the mold is equalized. Thus, the molding sand is subjected to a two-sided equal but opposite pressure. At the end of the pressing process, the molding box 3 and the filling frame 2, 9 assume the position shown in FIG. 1b. The ram 1 has covered the path 2h _$, the molding box 3 has covered the path h.

In Fig. 2 an example of a solution to the problem of manufacturing boxless molds according to the invention is shown. What is essential here is the fact that when the mold is ejected from the molding box 3 by the ejection device 11 due to the friction of the molding sand on the molding box 3, the latter without a special lifting device, by the height h is lifted.

The advantages of the solution according to the invention from the previously known are:

1. Compared to pressing from above or from below, the solution according to the invention uses the same amount of energy a uniformly distributed compression (Fig. 1b) achievable · The method according to the invention can be molded higher models too.

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2. Compared to pressing with redensification, the method according to the invention gives the same quality twice less energy consumption and simpler molding machines. The efficiency of the molding machines is known to decrease due to the compression.

3. By setting the counteraction of notch 6 or spring 10, the compression curve can be the optimal technological Requirements can be adjusted.

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Claims (1)

Claims 1. Frozen for the production of casting molds on a Compression molding machine with a press head and a pattern plate, characterized in that the molding box (3) with its filling frame (2, 9) opposite the press head (1) and the molding machine lsch Is movable in the pressing direction, wherein the press head (I) is designed as an otempel and together with the model plate is put into the molding box filled with oand from above and below. 'd. Device for carrying out the method according to claim 1, characterized in that above and below the dome molding box (3) guided by centering bolts (5) are provided, the height of which in view of the desired degree of compaction of the jy.veili ;; s side is selected and the height of the aur. ^"£ jgron7.ung dos pressing stroke serving Vorsprunrs the Lodeilplabte (7) or the Great Tempele corresponds. ■ ;. 7oi ·: · L; l, t; ung after an; pru;. ', 1 ι -Iu raw ■ jAzfia.r. ■■ i cluii ;! , dii Ui: ': i AOiJ-JhLiIw vlt..i Il'v / -'V ^ t. U ^ L » ZUU AU.). IuO Jtill dt; Γ: · 'ι ■ · -; '■. ·;) !. · / ir ^{;. · I "I f} ' in -'- n '"' :) H τ: ' ^1ι ΜΓ · <· η ("U)) before : <> .- BATH ORIGINAL Blank page