Metal deforming – By use of closed-die and coacting work-forcer – Cup or shell drawing
Patent
1993-12-10
1995-07-25
Larson, Lowell A.
Metal deforming
By use of closed-die and coacting work-forcer
Cup or shell drawing
72449, B21D 2222
Patent
active
054351669
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a die cushion device for a press to obtain a cushion effect by means of a servo motor. The invention relates to a die cushion device which obtains a cushion effect by a numerical control of position and torque of a servo motor.
BACKGROUND ART
Conventionally, when drawing is performed for a workpiece by means of a press, a die cushion device is employed. The conventionally employed die cushion has been disclosed in Japanese Examined Utility Model Publication No. 2-25538. The disclosed die cushion comprises an air cylinder for elastically supporting a pad for providing a cushion and a hydraulic cylinder for controlling lowering speed of the pad. A flow rate of a working fluid discharged from the hydraulic cylinder is controlled by a numerically controlled servo valve so that necessary cushion force corresponding to the drawing process can be obtained.
However, the die cushion device comprising the air cylinder and the hydraulic cylinder, is large in size so as to require a large space for installation. Furthermore, since an expensive servo valve must be incorporated, the device per se becomes complicated and expensive.
In addition, in case press molding is to be performed through a plurality of steps, since each individual die cushion device is large in size and expensive as set out above, it is often practically impossible to install such die cushion devices for respective process steps in view of installation space and cost.
DISCLOSURE OF THE INVENTION
Therefore, it is an object of the present invention to provide a die cushion device which can solve the problems in the prior art as set forth above.
A more concrete object of the present invention is to provide a die cushion device for a press, which provides a cushion effect employing a servo motor.
A further object of the present invention is to provide a die cushion device for a press, which permits independent control of cushion force at various points.
A still further object of the present invention is to provide a die cushion device for a press, in which the die cushion device is constructed as a unit and can be adapted to respective process steps in a press molding through a plurality of process steps by employing the units in combination.
In order to accomplish the above-mentioned objects, a die cushion device for a press, according to the first aspect of the invention, comprises a pad arranged in a head of the press and supporting a lower die from below, and a cushion mechanism supporting the pad and providing a cushion force by controlling a servo motor.
According to the second aspect of the invention, a die cushion device for a press comprises a plurality of pad members forming a pad for supporting a lower die from below via a cushion pin, a rack lever connected to each pad member, a servo motor provided corresponding to each pad member, a reduction gear train for connecting the servo motor and the rack lever, and a numeric controller for numerically controlling each servo motor for providing a cushion force for each pad member.
According to the third aspect of the invention, a die cushion device comprises a die cushion unit formed by assembling a plurality of pad members forming a pad for supporting a lower die from below via a cushion pin, a servo motor, and a reduction gear train connecting between the rack lever and the servo motor, the die cushion unit being installed for a head in each step of press molding for producing a cushion force by numerically controlling the servomotor corresponding to press operation in each step.
The servo motor can be an electric motor. Also, the cushion mechanism may include means for converting rotational driving torque of the servo motor into a reciprocal motion energy. Also, the servo motor may initiate driving immediately before contact of divided dies of the press for preliminarily accelerating the corresponding pad.
On the other hand, the servo motor is controlled the speed, position and/or torque by a numeric controller.
Furthermore, the pad
REFERENCES:
patent: 1846610 (1932-02-01), Rhodes
patent: 2130528 (1938-09-01), Alexander
patent: 3023799 (1962-03-01), Le Tourneau
patent: 4896594 (1990-01-01), Baur et al.
Kabushiki Kaisha Komatsu Seisakusho
Larson Lowell A.
LandOfFree
Die cushion device for press does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Die cushion device for press, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Die cushion device for press will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-732939