Die cushion apparatus

• US 20050262915A1
• Filed: 06/01/2005
• Published: 12/01/2005
• Est. Priority Date: 06/01/2004
• Status: Active Grant

• Current Assignee: Komatsu Industries Corporation (Komatsu Ltd.), Komatsu Ltd.
• Original Assignee: Komatsu Industries Corporation (Komatsu Ltd.), Komatsu Ltd.
• Inventors: Baba, Kiyokazu
• Granted Patent: US 7,401,488 B2
• Time in Patent Office: Days
• US Class Current: 72/351
• CPC Class Codes: B21D 24/02 Die-cushions
• CPC Class Codes: B21D 24/04 Blank holders; Mounting means therefor

Abstract

A cylinder is formed in the lower portion of a cushion pad, and a piston coupled to an upper end of a rod is slidably contained in the cylinder. The rod is coupled to a rotary shaft of a servomotor. An oil pressure chamber is formed of an inner wall surface of the cylinder and a wall surface of the piston. The axial center of the oil pressure chamber is identical with the axial center of the rod. The pressure oil for alleviating an impact is filled in the oil pressure chamber. The pressure oil filled in the oil pressure chamber absorbs a force operating instantaneously at the cushion pad. According to this structure, the impact generated in a press machine can be alleviated.

Claims

1. A die cushion apparatus having a cushion pad, a servomotor for driving to raise or lower the cushion pad while applying an upward energizing force, and a support unit for transmitting a power of the servomotor to the cushion pad and supporting the cushion pad from below, comprising:

a hydraulic chamber filled with liquid and located between the cushion pad and the support unit and on a coaxial center of the support unit.

2. The die cushion apparatus according to claim 1, further comprising:

an exhaust unit for exhausting the liquid from the hydraulic chamber when the liquid becomes a predetermined pressure or higher.

3. The die cushion apparatus according to claim 1, further comprising:

a pressure sensor for measuring a pressure of the liquid, and

a control unit for controlling an operation of the servomotor by using a measured value of the pressure sensor.