Breakthrough buffer for presses and control method therefor

Cutting – Processes

Patent

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Details

83 72, 83 75, 836391, 836395, 100 35, 100 50, 72 172, 72 198, B26D 512

Patent

active

056736010

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to a breakthrough buffer for presses and to a control method therefor, and particularly to improvements of a breakthrough buffer for presses, for reducing noise occurring during blanking using a mechanical press, and to a control method therefor.


BACKGROUND ART

Buffers according to the prior art are disclosed, for example, in Japanese Patent Publication No. 60-21832 and Japanese Patent Application Laid-open No. 52-19376. These buffers have a rod, a piston, a cylinder, a throttle valve, and the like, and utilize as a buffering force a flowing resistance which occurs when oil flowing out from a cylinder chamber passes through the throttle valve, thereby reducing the noise of the breakthrough of the punch.
However, in order to effectively reduce noise by buffering the breakthrough of the punch, it is necessary to finely regulate the timing of the buffering against the timing of the blanking. A spacer is attached to the rod or the like for this regulation. Since an optimum timing varies depending on blanking conditions, such as the plate thickness, the shape and size of the punch, the material of the plate, the temperature, and the like, this method requires a worker to ascertain an optimum timing by trial and error each time any of the blanking conditions change, and to set the timing accordingly. Even when the optimum timing is set, a change of conditions (temperature, etc.) during blanking will cause the timing to deviate, with a resultant occurrence of a problem in actual use. Another problem is that utilizing a flowing resistance induced by throttling requires a slide to lower against the flowing resistance after the breakthrough of the punch, thus causing the press to do excess work.
FIG. 15A shows the load of a press in a conventional blanking state, i.e. the load exerted on the press at blanking. FIG. 15B shows an oil pressure in a buffer cylinder in the conventional blanking state, indicating that the pressure remains unchanged. FIG. 15C shows the displacement of a slide in the conventional blanking state. FIG. 15D shows the sound pressure of noise in the conventional blanking state, indicating that the noise level is higher. FIG. 16A shows the load of a press when buffering is performed using conventional throttling, indicating that the press does excess work, represented by the area W, after the breakthrough of the punch. FIG. 16B shows an oil pressure occurring in the buffer cylinder when buffering is performed using conventional throttling.


SUMMARY OF THE INVENTION

In view of the foregoing conventional problems, it is an object of the present invention to provide a breakthrough buffer for presses, capable of reducing noise occurring during blanking using a mechanical press and a control method therefor.
According to the present invention, the breakthrough buffer for presses for buffering the breakthrough of a punch occurring during blanking in a mechanical press comprises a buffer body disposed below the punch plate of the press and cushioning the punch plate during the breakthrough of the punch, a timing regulator connected to the buffer body and regulating the timing of the buffering during the breakthrough of the punch, and a controller adapted to send out a command for a regulating position to the timing regulator during the breakthrough of the punch.
Pipings from the buffer bodies are independently connected to the timing regulator, or are integrated into one piping and then connected to the timing regulator.
Moreover, the ratio of the cylinder diameter of the buffer body to a pipe diameter is so selected as to minimize a noise level.
In addition, in the control method for the breakthrough buffer for presses, the noise, or the vibration of a slide, or the like, occurring during the breakthrough of the punch is detected, and a command is sent out from the controller to the timing regulator to regulate the timing of the buffer body, whereby the noise or the vibration of the slide, or the like, is minimized.
According to the above construction

REFERENCES:
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patent: 4945742 (1990-08-01), Schoch
patent: 5299478 (1994-04-01), Schorn et al.
patent: 5345861 (1994-09-01), Brewer et al.
patent: 5361615 (1994-11-01), Kirii et al.
patent: 5390574 (1995-02-01), Schorn

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