Metal deforming – With means to drive tool – With means to selectably control movement of tool
Patent
1999-05-24
2000-11-14
Jones, David
Metal deforming
With means to drive tool
With means to selectably control movement of tool
72 1, 72441, B21J 920
Patent
active
061453668
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a ram control method and ram control system for use with a press brake which bends a sheet-like workpiece by the cooperative movement of a movable die and a fixed die, the movable die being supported and driven by a ram, while the fixed die being supported on a fixed bed in opposing relationship with the movable die.
BACKGROUND ART
When using dies under pressure more than an allowable value in a press brake, there is the risk of breakage which is very dangerous for the operator. Therefore, press brakes of the above type are generally provided with an overload protector which restricts the pressure of the ram for driving the movable die so as not to exceed an allowable value.
One of conventional overload protectors is disclosed in Japanese Patent Publication (KOKAI) Gazette No. 6-154871 (1994) according to which the pressure applied between the upper and lower dies is detected and if it is determined from the detected value that an abnormal condition or overload condition has occurred, the press brake is brought to an emergency stop.
Although the pressure can be constantly checked in the method disclosed in this publication, it disadvantageously requires a specialized device for pressure detection. In addition, a pressure high enough to cause die breakage is exerted between the upper die (punch) and the lower die (die) until an abnormal condition is detected and the dies are, therefore, susceptible to damage. In cases where the ram which supports the movable die is driven by servo motors, the ram moves at high speed. Therefore, there is the possibility that the pressure caused by the movement of the ram cannot be detected in time so that the dies will be broken before detecting overload.
The present invention is directed to overcoming the foregoing problems, and the prime object of the invention is therefore to provide a ram control method and a ram control system adapted for use in a press brake, which are capable of avoiding the risk of die breakage due to collision caused by input errors of bending data, without use of an additional, specialized device for pressure detection.
DISCLOSURE OF THE INVENTION
According to the invention, the above object can be accomplished by a ram control method for a press brake which bends a sheet-like workpiece by the cooperative movement of a movable die and a fixed die, the movable die being supported and driven by a ram, while the fixed die being supported on a fixed bed in opposing relationship with the movable die, the pressure of the ram to a certain limit value which does not cause damage in the event that the movable die and the fixed die interfere with each other and setting the moving speed of the movable die to a lowest torque moving speed according to the set limit value and for driving the ram to exert the set pressure.
The method of the invention includes a die interference checking step, in which if there is the chance of interference between the movable die and the fixed die, for instance, at a start of operation, the pressure of the ram which supports the movable die is set to such a certain limit value that does not cause damage in the event of interference between the movable die and the fixed die and the ram is driven so as to create the set pressure at a lowest torque moving speed determined from the set pressure. The provision of the die interference checking step makes it possible to check, before starting an actual bending operation, whether or not the movable die and the fixed die will interfere with each other. With this arrangement, the collision of the dies due to an error made by the operator in the entry of bending data or in die alignment can be prevented. Additionally, since the moving speed of the ram is controlled, the operator can easily interrupt the operation whenever he feels danger. Not only can die breakage and therefore damage to the machine body be prevented, but also the operator endangered by die breakage can be protected.
Preferably, the invention includes a die interferenc
REFERENCES:
patent: 5027631 (1991-07-01), Naito
patent: 5031431 (1991-07-01), Naito
Jones David
Komatsu Industries Corporation
Komatsu Ltd.
LandOfFree
Ram control method and ram control system for press brake does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Ram control method and ram control system for press brake, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ram control method and ram control system for press brake will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2054120