Method for manufacturing molded member

A method for manufacturing a molded member by carrying out multi-stage drawing on a base metal sheet, the molded member comprising:

• a tubular body;
• and a flange formed at an end portion of the body,
• wherein the multi-stage drawing comprises:
• preliminary drawing for forming a preliminary body having a body element from the base metal sheet;
• at least one compression drawing performed after the preliminary drawing using a mold, the mold comprising:
• a die having a pushing hole;
• a punch for being inserted into the inside of the body element to push the body element into the pushing hole;
• and a compressing means for applying a compressive force along a depth direction of the body element to a circumferential wall of the body element, the at least one compression drawing forming the body by drawing the body element while applying the compressive force to the body element;
• and
• at least one finishing ironing performed after the at least one compression drawing;
• wherein the compressing means comprises a lifter pad, the lifter pad comprising:
• a pad portion which is disposed at an outer circumferential position of the punch so as to face the die, and on which a lower end of the circumferential wall of the body element is placed;
• and an urging portion, the urging portion being configured to support the pad portion from below and enable a supporting force for supporting the pad portion to be adjusted;
• wherein the at least one compression drawing is performed so as to be completed until the pad portion reaches a bottom dead center;
• wherein the supporting force acts upon the body element as the compressive force when performing the compression drawing of the body element;
• and
• wherein in the at least one finishing ironing process, an ironing ratio Y is defined by the following equation:
• Y
• 
• (
• %
• )
• =
• t
• re
• -
• c
• re
• c
• re
• ×
• 100
• in which:
• cre represents clearance of a mold used for the finishing ironing;
• and
• tre represents an average thickness of the circumferential wall of the body element before the finishing ironing;
• and
• a ratio X of a curvature radius r of a shoulder portion of a die of the mold used for the finishing ironing to the average thickness tre of the circumferential wall of the body element before the finishing ironing is defined as:
• X=r/tre;
• and
• wherein the ironing ratio Y is determined so as to satisfy the following equation with respect to the ratio X:
• 0<Y≤19.8X−5.2