Designing by Computer Modeling and Casting Replica of an Antique of Early Islamic Period,in Vacuum Mould
One of the most precious relic of early Islamic period is the bowl remAlned in the use of founder of Islam. It was originally made from wood -tamarix articulata -later on,it was encased in metallic cup of silver and was engraved from exterior with an arabic verse. Using the photograph of bowl,first of all the prototype of the cup 41/2 in. dia and 13/4 in. in height was made from stAlnless steel, on die by pressure sinking and through hit and trial method and with the computer designing on Microsoft Woro. It was made almost of same size and shape as that of the relic. The curvature of the cup appeared in the pictures were traced on Microsoft Word. When we were fully satisfied, the metallic cup was handed over to carpenter for making cup of this size from wood tamarix articulata. The wooden cup made was used as pattern for making mould cavity in the vacuum mould. The vacuum applied from 0 -1 daN/cm2(0-104 daN/m2 ).The properties of the moulding sand used: 4％ H20, 21. 6％ clay, permeability No. 88, sieve analysis ASF No. 121. Brass with composition,Cu=60％ ,Zn=27％ ,Sn=trace O.6％ and some other elements) was melted in gas fired furnace and was cast in vacuum mould at 1050℃. The vacuum pump was started immediately after pouring and it was operated till the casting solidifies and vacuum was the increased step by step upto O.8 daN/cm2, The casting produced was checked and was found free of any casting defect such as scab, rattAll, surface imperfection, blowholes, misruns, hot and cold tears. This was due the fact that the vacuum applied on the green sand mould created depression and trajectory of gases entering in the casting during solidification was reversed and condensation zone was shifted away from the casting wall. Beside this when the active mould surface was impregnated with polystyrene soln. in Col, ,increases the contact angle of liq. alloy with mould surface almost 45 - 55％ reduces dia and volume the pores of mould surface thus reducing the chances of entrance of gas bubbles in liq. alloy. The bowl cast was fettled and verse was embossed on its exterior. The cup made from the wood was then fixed in it.
Pervaiz Habibullah M. Arshad Virk
Pakistan Standards & Quality Control Authority, Lahore Centre
国际会议
69th World Foundry Congress(第69届世界铸造会议 WFC 2010)
杭州
英文
517-523
2010-10-16（万方平台首次上网日期，不代表论文的发表时间）