Hot press mold, temperature measuring device, and hot press molding method

A hot press mold for pressing a heated workpiece, thereby molding and quenching the workpiece, comprising:

• a temperature measuring device configured as a stroke sensor elongating/contracting by the pressure added via the workpiece,
• wherein the temperature measuring device is arranged to project outward from a molding surface of the mold, and when the workpiece is in contact therewith, the measuring device contracts and goes into the mold in response to the pressure from the workpiece,
• wherein the temperature measuring device comprises:
• first and second elastic members, each of which contacts by the pressure from the workpiece;
• a thermocouple for measuring the temperature of the workpiece, arranged at the head;
• a protector disposed between the workpiece and the thermocouple to prevent the direct contact therebetween;
• a supporter for the thermocouple and the protector;
• and
• a fixing portion supporting the supporter, used for attaching the temperature measuring device to the mold,
• wherein the first elastic member is disposed at the supporter to bias the protector toward the head side,
• wherein the second elastic member is disposed at the fixing portion to bias the supporter toward the head side,
• wherein the spring constant of the first elastic member is smaller than that of the second elastic member, and
• wherein the temperature measuring device elongates/contacts in two steps by the first and second elastic members.

A temperature measuring device installed in a hot press mold for pressing a heated workpiece, thereby molding and quenching the workpiece, measuring the temperature of the workpiece while hot press molding, the device comprising:

• a thermocouple for measuring the temperature of the workpiece, arranged at the head;
• a protector disposed between the workpiece and the thermocouple to prevent the direct contact therebetween;
• a supporter for the thermocouple and the protector;
• a first elastic member disposed at the supporter, biasing the protector toward the head side;
• a fixing portion supporting the supporter, used for attaching the temperature measuring device to the mold;
• and
• a second elastic member disposed at the fixing member, biasing the supporter toward the head side,
• wherein the spring constant of the first elastic member is smaller than that of the second elastic member, and
• wherein when the pressure from the workpiece is added to the protector, the first elastic member contracts faster than the second elastic member.

A hot press molding method for pressing a heated workpiece, thereby molding and quenching the workpiece, comprising:

• measuring a temperature of the workpiece while hot press molding by using a contact sensor;
• calculating a cooling gradient of the workpiece in quenching on the basis of the measured temperature;
• checking go/no-go of the hot press molding on the basis of the calculated cooling gradient, and determining which process includes a defect;
• and
• feeding back the determination of the defect to the process.