DE1169085B - Core binder - Google Patents

Description

Core binder Core binder made from a cereal binder, a sugar, is sufficient Water for blending the mixture and an inorganic additive are known.

In previous practice, the cereal binder, e.g. B. pregelatinized Starch, first added so that the freshly formed moist core is sufficiently wet or Has green strength to maintain its shape until placed in the oven will. In addition, the baked core must have high dryness or baking strength, which is mostly produced by the kernel oil in the process described. the Components added to produce wet or dry strength can be used against one another works. For example, kernel oils reduce the wet strength of sand mixtures. This is sometimes is a serious drawback, and it is an object of the invention to eliminate this drawback to eliminate the fact that the oil is replaced by a binder, which increases the wet strength not affected.

Cores develop gases when molten metal flows around them. Because these gases can be trapped in the pouring, any means in order to minimize the volume of the evolved gases, of great importance, because it provides a solid metal free of pores and voids. Another goal of the invention is therefore the volume of organic binders, in particular Cereal binders and sugar core baked sand cores reduce gases evolved.

The binder according to the invention is characterized in that it For every 100 parts of core sand to be bound 0.25 to 2 parts of cereal binder, 0.5 to 5 Parts of sugar and 0.002 to 1.05 parts of hydrochloric acid or a mixture of paraformaldehyde and ammonium chloride or a mixture of paraformaldehyde and hydrochloric acid or boric acid contains. This binder is used in the manner customary in foundry technology.

Unexpectedly, the binder according to the invention is satisfactory Preserved wet and dry strength of the cores. They also bake with this binder cores produced just as quickly or more rapidly than those with starch binders and kernel oil also emit far fewer gases than these.

The sugars used according to the invention include mono- and disaccharides of aldose or ketose character or those non-reducing saccharides which under the conditions of use with the formation of aldose or ketose saccharides can be hydrolyzed. For example, sucrose is effective as an ingredient of the new binder and falls under the invention, while this for sorbitol is not the case.

The preferred sugars are dextrose, sucrose and fructose or their Mixtures, however, maltose and lactose are also satisfactory, albeit because of less suitable for their price. Beet or cane sugar molasses (mother liquors in the manufacture of sucrose) and initial runs and hydrol (mother liquors in the manufacture of dextrose) can also be used satisfactorily in conjunction with the still to chemical additives may be used, although it should be borne in mind that molasses and Hydrol are not as easily handled as the sugars mentioned due to their toughness can be. Syrups, which are produced by hydrolysis of starch or beet sugar by means of Appropriate treatments can also be made to perform the Invention useful. Dextrose drains or hydrol can be treated to cause crystallization to prevent the dextrose it contains, by boiling it with acid or Alkali according to known methods. These by-products can be less effective than Be dextrose or sucrose, as can be seen from the figures in the table, but lie within the scope of the invention because of economic advantages.

The chemical additives useful for the purposes of the invention are Hydrochloric acid, a mixture of Paraformaldehyde and ammonium chloride, a mixture of paraformaldehyde and hydrochloric acid, and boric acid.

The amounts of additives, cereal binders and sugars can vary widely Vary in scope. 0.25 to 2 parts cereal binder, 0.5 up to 5 parts of sugar and 0.002 to 1.5 parts of additive can be used. The amount of water can vary from 1.5 to 6.0% of the sand. In general, the volume of gases evolved by baked kernels, as well as that required for the kernels Heating time to achieve peak strength is reduced when the proportion of Additive in the sand is increased.

It is known to use certain carbohydrates with or without seed oil in core binders and also to use various additives. It's also a binder from more than 20% protein (calculated oil-free), from completely or partially de-oiled oilseeds obtained, as well as water-soluble salts such as oxalates, borates, fluorides, phosphates, Sulphates, chlorides or carbonates, became known as modifiers. It can also include wheat flour, sulphite waste liquor, molasses and the like, for example as well Contains dry milk. Milk is a preferred additive, and is among the salts Sodium methaphosphate preferred. According to the example, the binder consists of 40 Parts milk powder, 60 parts soybean oil, 5 parts sodium oxalate. Comparative experiments have shown that this means completely different from the agent according to the invention is unusable is.

The invention is to be illustrated by the following example, which is only intended to illustrate and teach and is not intended to limit the invention in any way.

Example This example shows how the firmness of the baked Cores will enlarge when certain additives are applied with the binders.

Various core mixes containing starch binders, sugar and sugar together with an additive were prepared as follows: Tensile strength of baked test cores Sugar chemical additive parts of the chemical baking time tensile strength to 100 parts of sugar hours kglcmE Dextrose hydrate none 0 0.5 8.5 Dextrose hydrate none 0 1 12.5 Dextrose hydrate hydrochloric acid 0.2 1 16.2 Dextrose hydrate hydrochloric acid 10.0 1 19.1 Dextrose hydrate boric acid 10.0 1 13.9 Dextrose hydrate paraformaldehyde 5.0 1 14.1 Dextrose hydrate hydrochloric acid 0.1. Dextrose hydrate paraformaldehyde 5.0 1 15.7 Dextrose hydrate ammonium chloride 0.1 A weighed amount of American Foundrymen's Society Standard 50-70 sand was poured into a mixer. To this end, 1 percent by weight of pregelatinized starch binder, produced according to the teaching of the USA patent 1939973 and sold under the trade name "Mogul", was added. Then 1% by weight of a sugar, the kind of which is described in the table, was added. This mixture served as a control. Equal mixtures of starch binder and sand were then made and 1 percent by weight of a mixture prepared by thoroughly mixing 100 parts of sugar and the amount of an additive according to the table was added.

In each case the whole mass was mixed for an appropriate time, the mixer stopped, 3 weight percent water was added and the mixture resumed mixed up. When hydrochloric acid was used, it was found as a solution in the water and not added as a mixture with the sugar. Sample cores were made according to a procedure manufactured as specified by the American Foundrymen's Society (Foundry Sand Handbook, 6th Edition, published in 1952 by the American Foundrymen's Society, Chicago) is recommended, and have been in an oven at 205 ± 5 ° C for the length of the Baked time according to the table. Such cores were tested for tensile strength after procedures described in the mentioned manual and the results are indicated in the table. After baking was complete, the samples were taken from the Oven removed, cooled to room temperature and the breaking strength with a suitable Machine determined. These results can also be found in the table.

In the cases shown in the table, using a liquid binder was used, the starch binder was mixed with the sand, water was added and blended and then added the liquid binder and blended. If the If the addition was a dry powder, it was added with the starch binder. if when the additive was available as a liquid, it was dissolved in the water.

Claims (1)

Claim: Binder for core sand, consisting of a cereal binder, a sugar, enough water to mix the mixture and an inorganic additive, characterized in that for every 100 parts of core sand to be bound there is 0.25 to 2 parts cereal binder, 0.5 contains up to 5 parts of sugar and 0.002 to 1.05 parts of hydrochloric acid or a mixture of paraformaldehyde and ammonium chloride or a mixture of paraformaldehyde and hydrochloric acid or boric acid. Considered publications: German Patent Nos. 840 426, 874 202, 572 019, 742 396; U.S. Patent No. 2,206,369; IB Kumamn and AM Lj ass, "Kernbinderwerkstoffe", Berlin 1953, p. 149; "Die Gießerei", 1943, pp. 248/249; Chemisches Zentralblatt, 1946 / I, p.782 (French no. 912875); 1941/1, p. 1876; (USA No. 2206369); 1951 / I, p.1051 (DT K ershaw).