Pre-tensioned sand core

Abstract

Provided are methods of replacing drilling holes in castings by pre-tensioning sand cores. This methods are used in long cylindrical shaped sand cores in cold core box processes. The urethane sand core is placed in compression to increase the core strength during handling, placing inside of the mold. The pre-tensioned urethane sand core is set in a casting mold so as to form a cavity in the casting mold. The molten metal is poured to form the cavity inside of the casting. The pre-tensioned urethane sand core maintains its initial shape during casting.

Description

[0001] Cross References to Related Applications [0002] This application claims priority to US Provisional Patent Application No. 60 / 604621, filed August 25, 2004, which is hereby incorporated by reference in its entirety. technical field [0003] The present invention relates to the improvement of the method of using polyurethane sand cores, and can achieve higher quality, and at the same time, it also facilitates the manufacturing process of polyurethane sand cores. The invention also relates to an improvement in the manufacturing process by replacing the deep hole drilling operation with casting, thereby improving the duty cycle of the manufacturing process. Background technique [0004] To date, a variety of manufacturing methods have been used to process metals, plastics, and ceramics. Casting is now widely used as part of machining to fabricate metals. Spray casting has been widely used to manufacture molded plastic or ceramic parts. For these manufacturing process...

AI Technical Summary

Problems solved by technology

The latter disintegrating cores are usually made of molding sand and thus have the disadvantage that the cores are difficult to form into predetermined shapes and have a tendency to crumble, thereby making them difficult to handle

This laborious operation increases the number of steps in the process flow, while increasing man-hours and costs for the manufacturing process

[0008] (2) After casting, it is difficult to completely remove the adhesive that is a constituent of the coating material and sand core

The combustion step increases the number of steps in the process flow while adding man-hours and cost to the manufacturing process

[0009] (3) The sand core is difficult to be made, and complex equipment and considerable steps are required in the manufacturing process

These phenomena tend to form small holes or cavities in the casting, thereby reducing the yield and productivity of the casting (product)

[0012] (6) It is difficult to completely remove the molding sand of the sand core after casting, so that the molding sand will adhere to the casting (product), thereby causing wear and damage of the casting (product)

[0013] (7) It is difficult or substantially impossible to manufacture complex and / or large castings

[0020] (1) It is difficult to control the coolant flow, causing the deep hole drill bit to break

[0021] (2) The use of the deep hole drill exceeds its expected life, which will also cause the fracture of the deep hole drill