US3388478A - Method for cooling castings - Google Patents

Description

June 18, 1968 H. VISSERS METHOD FOR COOLING CASTINGS Filed Sept. 23, 1965 INVENTOR HEWBH? T V/JsERS ALH' ORNEY United States Patent 3,388,478 METHOD FOR COOLING CASTINGS Herbert Vissers, Nieuw Vennep, Netherlands, assignor to Landbouwwerktuigenen Machinefabriek H. Vissers, N.V., Nieuw Vennep, Netherlands, a company of the Netherlands Filed Sept. 23, 1965, Ser. No. 489,714 Claims priority, application Netherlands, Oct. 9, 1964, 6,411,744 4 Claims. (Cl. 34-13) ABSTRACT OF THE DISCLOSURE The mold sand and cast metal contents of the mold flask are dumped into a horizontal drum wherein these contents are tumbled into intimate contact to simultaneously cool the cast metal and to dry the mold sand. The drum has an imperforate inlet section wherein the cooling and drying mainly takes place and beyond this is a perforate section from which the dry mold sand is discharged. A sleeve around the drum and longitudinally adjustable thereon may be positioned to block ofi part of the perforate section.

The invention has for its object to carry out the cooling of the castings rapidly without causing damage to the castings after the flasks have initially been cooled. With this object in view the contents of the flasks according to the invention are dumped into a room provided with an outlet for the generated steam and the castings and the mold sand remain in said room in intimate contact with each other during a predetermined time. When dumping the contents of the flasks in said room the flasks have a temperature of about 600 C. but the mean temperature of the mold sand is much lower and depends on the ratio of the quantities of metal and sand, the surface area and the volume of the casting. As when dumping the contents of the flasks into said room the sand will lie loosely between the castings the transfer of heat from the castings to the loose sand is relatively favourable and the moisture contained in the sand is converted into steam in short time whereby the heat taken up by the sand is rapidly withdrawn. Said withdrawal of heat may still be increased by supplying an additional quantity of moisture into the room dependent on the ratio of the quantities of metal and sand or by maintaining a reduced pressure in said room.

With a practical embodiment of the method according to the invention the room mentioned above may advantageously be constituted by a rotary drum as by the rotation of the drum the castings are continuously contacted by other quantities of sand whereby the withdrawal of heat from the castings will be eflicient. The foremost part of the drum which has an unperforated circumferential wall then constitutes the room for cooling the castings and for drying the sand. To said first unperforated part of the drum a part having a perforated wall is joint. The withdrawal of heat from the castings may still be furthered by generating a flow of air of lower temperature through the drum preferably in counter current to the castings.

The invention will be further described with reference to the accompanying drawing showing a diagrammatical longitudinal section of a drum for carrying out the method according to the invention.

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The drum 1 is rotatably supported on rollers 2 and at one of its end walls is provided with an inlet 3 for emptying the flasks into the drum and at its opposite end wall with an outlet 4 for castings freed from sand and with an outlet 5 for the generated steam.

The circumferential wall of the drum is provided with perforations 6 on part of its length and said perforations may have a diameter of about 0.8 inch and a pitch of e.g. 8 inches. The length of said perforated wall part of the drum may be varied by providing one or two slidable sleeves 9 around the drum. The sand passed through the perforations 6 is completely dry "and contains no lumps as said lumps have been pulverized by the castings and the sand drops into a stationary chute 7 tightly engaging the wall of the drum. If required water may be introduced into the drum by means of a conduit 8.

The first part of the drum wall in which the contents of the emptied flasks are received has no perforations as said part of the drum serves as a drying zone. The movement of the mass in the drum is obtained in known manner by means of blades (not shown) secured at the inner side of the drum wall and which preferably are adjustable for varying the speed of the movement of the mass and thus the cooling of the castings. The evaporation of the water contained in the sand and therefore the cooling of the castings and of the sand may be accelerated by maintaining a reduced pressure in the drum.

For obtaining favourable results the degree of filling of the drum should be maintained between predetermined limits. The castings leaving the drum through the outlet 4 are already partly cleaned so that the treatment thereof by means of a blast of steel grit may be shortened and beating out the cores if any is not necessary. It appears that by the short duration of treatment in the drum the shape and the dimensions of the sand grains are not affected. As the sand is obtained completely free of moisture the addition of water when mixing sand for repeated use for making mold may be maintained within narrow limits. Also the advantage is obtained that the moisture free sand in a thin layer of e.g. 0.2 inch may be moved over a magnet for withdrawing particles of iron as far as possible from the sand. Moreover, the completely dry sand will not tend to adhere together when stored.

What I claim is:

1. A method for cooling castings and for drying the mold sand used for said castings, which comprises,

dumping the mold sand and solidified casting contents of mold flasks into a rotatable drum while the castings are still hot,

tumbling the castings in intimate contact with the mold sand for a time sutficient to cool the castings by drying the mold sand,

and then separating the dry mold sand from the castings and separately discharging the dry mold sand and castings from the rotating drum.

2. The method according to claim 1 wherein cooling liquid is introduced into the drum while the castings and mold sand are being tumbled in intimate contact, the amount of cooling liquid introduced being sufficient to cool the castings but insufficient to be retained by the mold sand.

3. A machine for cooling castings and drying mold sand, comprising a substantially horizontal cylindrical drum,

means mounting said drum for rotation about its longitudinal axis,

said drum having an inlet opening at one end and a discharge opening at its other end, and said drum having a circumferentially perforate section between such ends to define an imperforate mold sand and casting section at said perforate section,

and means for varying the axial extent of said imperforate mold sand and casting section to encroach upon said perforate section.

4. The machine according to claim 3 including means for introducing cooling liquid into said drum.

References Cited UNITED STATES PATENTS FREDERICK L. MATTESON, JR., Primary Examiner. D. A. TAMBURRO, R. A. DUA, Assistant Examiners.

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