There are provided a die cushion force control method and a die cushion device that can improve response delay of die cushion force without changing die cushion waiting position upward. In the die cushion force control method, a servo motor is driven according to a die cushion force command B previously set and the die cushion force is generated on the cushion pad. The die cushion force control method includes a step of allowing the cushion pad to wait in a predetermined die cushion waiting position at which a die cushion force action will start, and a preliminary pressurization step of outputting the die cushion force command B and preliminary applying pressure to the cushion pad before a slide of a press machine reaches the die cushion waiting position.

There are provided a die cushion force control method and a die cushion device that can improve response delay of die cushion force without changing die cushion waiting position upward. In the die cushion force control method, a servo motor is driven according to a die cushion force command B previously set and the die cushion force is generated on the cushion pad. The die cushion force control method includes a step of allowing the cushion pad to wait in a predetermined die cushion waiting position at which a die cushion force action will start, and a preliminary pressurization step of outputting the die cushion force command B and preliminary applying pressure to the cushion pad before a slide of a press machine reaches the die cushion waiting position.

The present invention provides a servo press system and a drawing method using the servo press system. The drawing method according to the aspect of the present invention includes: a stopping step of stopping the slide for a first period in a course of a stroke for performing drawing; a keeping step of reducing the die cushion force to below a predetermined die cushion force and keeping the die cushion force for a second period within the first period for which the slide is stopped; and a restarting step of restarting the slide after keeping the die cushion force for the second period, wherein drawing including the stopping step, the keeping step, and the restarting step is performed at least one time in the course of the stroke for performing drawing.

The present invention provides a servo press system and a drawing method using the servo press system. The drawing method according to the aspect of the present invention includes: a stopping step of stopping the slide for a first period in a course of a stroke for performing drawing; a keeping step of reducing the die cushion force to below a predetermined die cushion force and keeping the die cushion force for a second period within the first period for which the slide is stopped; and a restarting step of restarting the slide after keeping the die cushion force for the second period, wherein drawing including the stopping step, the keeping step, and the restarting step is performed at least one time in the course of the stroke for performing drawing.

A die cushion device includes a hydraulic cylinder that supports a cushion pad and generates die cushion force when the slide of the press machine descends, a first hydraulic circuit that is connected to a cap side hydraulic chamber of the hydraulic cylinder, and a second hydraulic circuit that is connected to a rod side hydraulic chamber. Before die cushion force control starts, the second hydraulic circuit of the die cushion device causes hydraulic oil in the rod side hydraulic chamber to be prevented from flowing out, and the first hydraulic circuit of the die cushion device causes the cap side hydraulic chamber to be pressurized.

A die cushion device includes a hydraulic cylinder that supports a cushion pad and generates die cushion force when the slide of the press machine descends, a first hydraulic circuit that is connected to a cap side hydraulic chamber of the hydraulic cylinder, and a second hydraulic circuit that is connected to a rod side hydraulic chamber. Before die cushion force control starts, the second hydraulic circuit of the die cushion device causes hydraulic oil in the rod side hydraulic chamber to be prevented from flowing out, and the first hydraulic circuit of the die cushion device causes the cap side hydraulic chamber to be pressurized.

The die cushion force setting apparatus according to an aspect of the present invention allows die cushion forces (component forces) acting on plural driving shafts to be set easily, makes it easy to apply strong or weak die cushion forces to a complex-shaped drawn part in a plane of a cushion pad, and provides a smooth die cushion force distribution. An operator manually enters a total die cushion force, axial component force of a left front hydraulic cylinder, and center-of-force position by operating an input device. Based on the information entered via the input device, the numerical computing device B1 calculates axial component forces of three hydraulic cylinders through numerical computations. The one axial component force thus entered and three axial component forces thus computed numerically are set as the axial component forces of four hydraulic cylinders.

The die cushion force setting apparatus according to an aspect of the present invention allows die cushion forces (component forces) acting on plural driving shafts to be set easily, makes it easy to apply strong or weak die cushion forces to a complex-shaped drawn part in a plane of a cushion pad, and provides a smooth die cushion force distribution. An operator manually enters a total die cushion force, axial component force of a left front hydraulic cylinder, and center-of-force position by operating an input device. Based on the information entered via the input device, the numerical computing device B1 calculates axial component forces of three hydraulic cylinders through numerical computations. The one axial component force thus entered and three axial component forces thus computed numerically are set as the axial component forces of four hydraulic cylinders.

A slide cushion device includes: a hydraulic cylinder group integrally formed in a board provided immediately below a slide; a pressing member that is disposed in a recessed portion of an upper die that vertically moves together with the slide, in a vertically movable manner; a plurality of slide cushion pins that is provided in the pressing member and penetrates the upper die to be brought into contact with a piston member of the hydraulic cylinder group, wherein a number of the cushion pins is less than a number of hydraulic cylinders disposed in a plane of projection of the recessed portion; and a slide cushion hydraulic device that controls hydraulic pressure to be supplied to a compression chamber of the hydraulic cylinder with which a slide cushion pin is to be brought into contact.

A slide cushion device includes: a hydraulic cylinder group integrally formed in a board provided immediately below a slide; a pressing member that is disposed in a recessed portion of an upper die that vertically moves together with the slide, in a vertically movable manner; a plurality of slide cushion pins that is provided in the pressing member and penetrates the upper die to be brought into contact with a piston member of the hydraulic cylinder group, wherein a number of the cushion pins is less than a number of hydraulic cylinders disposed in a plane of projection of the recessed portion; and a slide cushion hydraulic device that controls hydraulic pressure to be supplied to a compression chamber of the hydraulic cylinder with which a slide cushion pin is to be brought into contact.