Heydari, Farhad (1990) Mechanisms of sand flow and compaction in core-blowing. EngD thesis, University of Warwick.

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Abstract

The effect of different control variables of the core-blowing process on the mechanism of sand flow inside core-boxes has been studied. These variables included the core-box geometry, the blowing air pressure, the sand/binder mixture, the area and arrangement of the core-box vents, and the area and shape of the blow hole.

A high speed cine-camera (64 frames/sec) was used to record the filling of the three core-boxes used. The blown cores were weighed in the boxes on scales accurate to 0.1 of a gram. They were then cured using sulphur dioxide (SO2) and checked for soundness.

The results showed that:

i) The filling pattern within a core-box can be controlled by the blowing conditions. Different patterns of filling can be achieved according to different; blow hole sizes and shapes, blowing air pressure settings and core-box venting arrangements, resulting in different degrees of sand compaction in the core-box.

ii) For a given blowing condition increasing the blowing air pressure and/or increasing the blow hole area to optimum values, gives rise to increasing the overall compaction of the core and its weight. The rate of change in the core-weight decreases as the optimum values of blowing air pressure and/or blow hole area are approached.

iii) The filling time of a core-box with sufficient venting is related to the area of the blow hole and the blowing air pressure. Insufficient venting of a core-box can give rise to prolonged filling times.

iv) Insufficient venting or over venting of a core-box leads to decreasing the core compaction and weight. One sided venting in the core-boxes used, resulted in faster filling and better sand compaction in those sides.

v) Compaction of the sand in the core-box is achieved under the influence of; the kinetic energy of the sand/air jet entering the core-box (Primary compaction), and the air flowing through the mass of sand in the core-box (Secondary compaction).

vi) Increasing the binder level in the mix led to the production of stronger cores. However it also led to core defects in the form of voids in areas where compaction is largely achieved as a result of the secondary compaction.

Item Type:	Thesis (EngD)
Subjects:	T Technology > TS Manufactures
Library of Congress Subject Headings (LCSH):	Coremaking -- Research, Core materials, Sand, Foundry, Compacting
Official Date:	1990
Dates:	Date Event 1990 Submitted
Institution:	University of Warwick
Theses Department:	Department of Engineering
Thesis Type:	EngD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Wallbank, J.
Sponsors:	Wallbank, J.
Extent:	150 leaves : illustrations
Language:	eng

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