PURPOSE: To reduce the time for assembling and to improve assembling strength and surface shape by winding tubes which shrink when heated at a low temp. to the joint parts such as product part, runner, riser, etc. of a pattern for a casting mold and heating the pattern until the tubes shrink.
CONSTITUTION: A PVC tube 4 which shrinks when heated is wound on the outside of the gate 3a of a product part 3 to attach the part 3 to a runner 2. The gate 3a is inserted into the attaching hole 2a of the runner 2 and the space between the hole 2a and the gate 3a is closed by the tube 4. A riser 5 is assembled to the runner 2 and a tube 6 is wound on the outside circumference of the end of a sprue 2 and the end of the riser 5 including both grooves 2b and 5a. When a pattern 1 for a casting mold made into a tree-like shape is heated, the tubes 4 and 6 shrink to fix the product part 3 to the runner 2 and to fix the riser 5 to the runner 2. The pattern 1 is then dipped in a slurry to form a coating layer on the outside and the casting mold is thus formed.
EKINO YOSHIO
YUUKI ISAMU
