CH86883A - Process for the production of core pieces for metal foundries. - Google Patents

Description

  

  Process for the production of core cords for metallic elements. In metal foundries, for example iron foundries, it is known that thick oils, for example so-called seed oil, linseed oil, vegetable syrup or thick molasses and the like, are preferably added as binders for the cores in the production of core pieces. All these core binders have the disadvantage that they can only be mixed with the core sand with great difficulty because of their viscosity; furthermore, a relatively large amount of these currently particularly expensive binders is required.

   It has also been proposed to use asphalt as a binder. This is supplied to the foundries in lump form and crushed by them in mills or disintegrators, where however the asphalt heats up and the mills or disintegrators smeared. It is not possible to achieve such a fine asphalt powder as would be required for a binding agent that meets all requirements.

   Since a relatively large amount of binding agent is required to achieve good binding of the core mass, and since asphalt is expensive, this means a lacquer part. All these disadvantages can be avoided if, in the production of core pieces for foundries, according to the present process, your core sand is added with bitumen that is powdered to the point of dust. Appropriately used in a biturne that has been converted into an amorphous state.

    It has been found that when using such a core binding agent as an additive to the core sand, only about 2-3% biturns in the finest powder form are required to produce unstable cores. As a biturnen bad luck can be.

   Use resin, asphalt and others. If pitch is used as bitumen, it can be converted into the finest powder form by forcing out the previously melted pitch in a thin liquid state through an appropriately designed atomizer nozzle using compressed air. The pitch can also be pulverized to a fineness of dust by using an air separator with the use of cooling water.

   The use of pitch that has been powdered to a fineness of dust has the particular advantage that it melts easily as a fine powder in the kiln and thus acts as a binding agent and gives your kernels great strength. During the subsequent casting, the fine pitch powder burns out of the cores completely, which means that they achieve the desired porosity and the gases can escape from the molds. As a result of the porosity achieved, the cores can be easily removed from the finished castings after cooling.



  In addition, the use of pitch pulverized to a fineness of dust by sprinkling nozzles has the advantage that it can be supplied to the foundries as a fine powder in tin drums or the like, which means that the foundries are relieved of the difficult and imperfect crushing of the pitch. The finely atomized pitch does not stick together again and remains in its fine state, because the pitch has been converted into such an amorphous state by the atomization that caking can no longer occur.

    Pitch converted into powder form in ball mills and the like does not have this favorable property and easily sticks together again when shipped.



  Instead of pitch, resin and asphalt can also be pulverized to dust fineness in the same way by atomization or by means of air separators and then added to the core sand in the method according to the invention.

 

Claims (1)

PATENT CLAIM: Process for the production of Kernstüelzeii for lletalliel:, free, characterized by adding bitumen that is powdered up to dust fineness to the liei @ nsancl # 2. SUBSTANTIAL CLAIM: Process according to patent claim, characterized in that 2-3% bitumen is added to the core sand.