Method of manufacturing modular cover of air bag

A method of manufacturing a modular cover for an air bag comprising,

• preparing a mold formed of a stationary die, a movable die movable toward the stationary die to define a cavity between the two dies and two tear-line impressing movable members attached to the respective dies and movable forward and rearward with respect to the cavity formed between the two dies, each movable member having an elongated projection for forming a tear-line and flat side faces on both sides of the elongated projection;
• withdrawing the movable members away from the cavity of the mold to form extra spaces adjacent the cavity;
• supplying a resin material into the cavity of the mold to fill the resin material in the cavity and the extra spaces;
• moving the respective movable members toward the cavity to positions where the flat side faces on both sides of the respective elongated projections are flush with respective outer surfaces of the cavity and the elongated projections project into the cavity so that tear-lines are formed in the resin material supplied into the mold and the resin material in the extra spaces is supplied to an area around the tear-lines with compression to provide enough density at the area around the tear-lines;
• hardening the resin material within the cavity of the mold;
• and
• separating the hardened resin material from the mold thereby obtaining the modular cover provided with the tear-lines on both sides of the modular cover with sufficient strength.