JPS5986795A - Safety circuit for press - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a safety circuit for a one-hand press.

Conventional safety circuits of this type operate the press only when a first operation button operated by one hand and a second operation button operated by the other hand are both pressed down. I was trying to keep it that way. However, if the contacts of these operation buttons are short-circuited, the press will start operating even if the normal operation button is operated, which is dangerous. It was designed to independently detect short circuits.

The present invention has been made in view of the above-mentioned circumstances, and aims to provide a safety circuit with a simple configuration that can detect both the simultaneous operation of one car operation button and a short circuit accident. There is.

The present invention will be explained in detail below based on an illustrated embodiment.

In the figure, FBI is a first operation button that is pressed and operated with one hand, PH1 is a second operation button that is pressed and operated with the other hand, and PH1 is a second operation button that is pressed and operated with the other hand.
The first relay X1 is connected to the power source through the normally open contact PB1a of the second operation button PB2, and the second relay X2 is connected to the power source through the normally open contact PB2a of the second operation button PB2. or.

After connecting the timer T to the power supply through the parallel circuit of the first normally open contacts Xla and X2b provided in both relays Xi and X2,
normally open contacts Xlb, X2b, normally closed contact t of timer T, normally closed contact X4a of auxiliary relay X4, which will be described later.

The press clutch brake relay X3 is connected to the power supply through a series circuit of the first normally open contact X5a of the restart prevention relay X5, and the first normally closed contact X3a of this relay X3 is connected to the normally closed contact t of the timer T. are connected in parallel to form a safety circuit.

In addition, the auxiliary relay
, PH1's normally closed contacts PB1b and PB2b are connected to the power supply through a series circuit, and restart prevention relay X5 is connected to the inching contact of operation selection switch SS1, normally closed contact Xad of press clutch brake relay After connecting to the power supply via the series circuit of the second normally open contact X4b of the auxiliary relay x4, connect the second normally closed contact X5b of the restart prevention relay X5 in parallel to the series circuit of both contacts X3d and X41). In addition, the 20th tally cam switch R82 is connected in parallel to the operation selector switch SSI to perform the restart prevention function similar to the conventional one. R8I is the rotary cam switch for safety stroke, SVI is the clutch brake solenoid valve, X3b, X3c are the normally open contacts of the clutch brake relay X3, and X4b is the auxiliary relay X4.
It is a normally closed contact.

In the above configuration, when the first operation button FBI is pressed, the first relay X1 is turned ON, and when the second operation button PB2 is pressed, the second relay X2 is turned ON. Also, the relay is ON
Then, the normally open contact closes and the normally closed contact opens, so press clutch brake relay In synchronization with ti+) relay X3's normally open contact (self-holding contact) X3a closes, so clutch brake relay X3 becomes 0. Continue NL. still.

When the amount of deviation between the pressing times of both operation buttons FBI and PH1 becomes longer than the set time of timer T, the normally closed contact t of timer T opens, the circuit to press clutch relay X3 is cut off, and nIJ relay X3 is activated. do not.

Therefore, if the deviation in operation time of the 9-car operation buttons PBI and PH1 becomes larger than the predetermined time and synchronization is lost, or if the 9-car operation buttons PBI and PH1 or relays XI and X2 are turned ON due to some malfunction. In this case, the contact t of the timer T turns OFF and continues to hold the relay X3 in an inoperative state, so safety is guaranteed.

On the other hand, if the timer T fails while it is still ON, its contact t is held in the OFF state, and the circuit to the press clutch relay X3 is cut off as in the case above, making the press inoperable. . In addition, in order to determine whether or not the timer T is malfunctioning until it reaches 1, which is OFF, it is sufficient to operate the press with one hand before operating the press to confirm that the press does not operate. When this occurs, timer T is in the OFF state and has malfunctioned.

As explained above, according to the present invention, not only one-handed operation is possible, but also two-handed operation or welding of the contacts because the press can be rendered inoperable even when the operation button, relay, timer, and their contacts are malfunctioning.

Accidents due to short circuits can be prevented and press safety can be improved.

[Brief explanation of drawings]

The figure is an electrical circuit diagram of one embodiment of the present invention.

Claims (1)

[Claims] A first relay connected to a power source via a first normally open contact of a first run button that is pressed and operated with one hand, and a first relay that is connected to a power source through a first normally open contact of a first run button that is pressed and operated with one hand; a second relay connected to a power source through a normally open contact of the first relay; a timer connected to a power source through a parallel circuit of normally open contacts of both relays; and a series circuit of normally closed contacts of both relays. A series circuit of the auxiliary relay connected to the power source, the second normally open contact of the first and second relays, the normally closed contact of the timer, the normally closed contact of the auxiliary relay, and the normally open contact of the restart prevention relay. A press clutch brake relay is connected to a power supply via a press clutch brake relay, and a normally open contact of the press clutch brake relay is connected in parallel to a normally closed contact of a timer.