JPS6144637B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a plurality of suction pads through an appropriate number of suction passages such as hoses branched from one suction source, and uses the suction pads to pick up one workpiece or a plurality of workpieces. This relates to a work suction control method in a work suction device when suction holding and conveying is performed, and if incomplete suction occurs in any suction pad before a predetermined time, the valve leading to it is closed to stop suction, This device is characterized in that it prevents the influence on other suction pads, and if incomplete suction occurs after a predetermined period of time, the valve leading to it is kept open to continue suction.

In other words, when an appropriate number of intake passages such as branched hoses are provided from one intake source and multiple suction pads are provided, if any of the suction pads has incomplete suction, the suction capacity of the other suction pads will be affected. and the required adsorption effect cannot be obtained.
Therefore, it is desirable to close the intake passage to the suction pad that is incompletely suctioned.

Furthermore, if incomplete suction occurs in any of the suction pads due to suction air leakage after the workpiece has been suctioned, if the suction passage is closed midway, the workpiece may suddenly fall, which is dangerous.

The present invention eliminates the above-mentioned drawbacks, and if incomplete adsorption occurs in any of the suction pads before a predetermined time, the valve in the intake passage is closed, and after the predetermined time, either of the suction pads is closed. This is characterized in that when incomplete suction occurs in the suction pad, the valve in the intake passage remains open.

An embodiment of an apparatus for implementing the present invention will be described in detail below with reference to the drawings.

FIG. 1 is an explanatory diagram showing an outline of the entire apparatus for implementing the present invention. 1 is an intake source consisting of an ejector pump that receives high-pressure air from the outside through a hose 2 and generates negative pressure in the intake passage a;
Vacuum pumps are also used as needed. An intake tank 3 is connected to the intake passage a, and the intake passages b, c, d, and e are further divided into four intake control devices 4a, 4 each having a valve.
b, 4c, 4d and suction pads 5a, 5b, 5
c and 5d are connected. Note that the above-mentioned valve is a well-known one, and the valve drive load 43 described below
When current flows through the intake passages b, c, d, and e, each intake passage opens, and when the current is interrupted, they close. Note that 6 is a workpiece that is sucked and held by each of the suction pads 5a to 5d. The intake control device 4
A to 4d are each equipped with a vacuum switch device as shown in FIG. 2 to detect the degree of vacuum in each of the intake passages b, c, d, and e, and act to control the intake operation according to the intake pressure.

That is, in FIG. 2, 7 is a cylindrical body having an air passage 7a and a bellows attachment hole 7b in the center, and terminal bushes 8, 9 are inserted through each passage 7a and attachment hole 7b to the outside. are screwed together. 10 is an O-ring that seals the passage 7a and the outside. Further, terminals 11 and 12 are screwed into the terminal bushes 8 and 9 from the outside, and their tips protrude into the passage 7a and the mounting hole 7b, respectively. An insulating bushing 13 and an insulating collar 14 are arranged in series in the passage 7a through which the tip of the end bushing 8 looks, and a terminal collar 15 is fitted around the insulating bushing 13, with which the tip of the terminal bushing 8 comes into contact. ing. 16
is a locking surface of the thick part to which the terminal bush 8 is attached, and a bellows seat 18 is engaged with this locking surface 16 via an O-ring 17, and the threaded portion of the insulating collar 14 is attached to the center of the bellows seat 18. is screwed in. On the other hand, an adjustment screw 19 that can be rotated from the outside is screwed into the center of the bottom plate (right side plate in the figure) 7c of the body 7.
A cylindrical contact member 20 is provided at the tip protruding into the inside of the
is installed. Further, the tip of the terminal 12 is in contact with this cylindrical surface. On the other hand, reference numeral 21 is a telescopic metal bellows whose one end edge is attached to the terminal bush 8, and whose other end edge is fixed to the insulating bush 22 and seal collar 23 via an O-ring 24 so as to be clamped. ing. A bellows contact member 25 in the form of a threaded rod is screwed into the center of the bush 22 and collar 23, and its right end extends into the center of the contact member 20. A flexible lead wire 26 has both ends connected to the left end of the contact member 25 and the terminal collar 15, and is guided within the insulating collar 14 and the bellows 21. Such a vacuum switch device sucks the air in the bellows 21 to create a negative pressure by the suction operation toward the left end opening of the body 7, and acts to separate the contact member 25 from the contact member 20. (depending on atmospheric pressure)
This is done by moving the adjustment screw 19 in and out. Further, when the above-mentioned intake operation ceases, the bellows 21 returns to the right in FIG. 2, and the contact members 20 and 25 come into contact with each other. Therefore, depending on whether or not the contact members 20 and 25 are in contact with each other, the degree of vacuum in each intake passage b, c, d, and e can be detected, and whether the suction is complete or incomplete. It is possible to detect whether the

FIG. 3 is an intake control circuit diagram, in which the opening/closing control of the valves for sucking air from each of the suction pads 5a to 5d is controlled by the contact member 2 by the operation of the bellows 21.
This is done in conjunction with the operations of 0 and 25.
27 is a NAND with two input terminals connected to the power supply
The output side of the circuit is connected to a differentiating circuit consisting of a capacitor 29 and a resistor 30 via an inverter 28, and the output side thereof is connected to a timer circuit 31 constituting an analog timer. Note that a backflow prevention diode 50 for protecting each element is connected to the resistor 30. On the other hand, the output side of the timer circuit 31 and the terminal 12 leading to the contact member 20 are connected to two input terminals of a NAND circuit 32, and on the output side there are two NAND circuits 33 forming an R-S flip-flop. 34, it is connected to one set input terminal.
Furthermore, the output side of the NAND circuit 33 is connected to the base of a transistor 37 via a diode 35 and a resistor 36. In addition, the NAND circuit 32
A bypass circuit 39 is connected to one input side of the diode 35 and the cathode side of the diode 35 via a diode 38 as shown. Reference numeral 40 designates a reset switch for the flip-flop, which is switched to ground the reset input terminal of the NAND circuit 34 at the time of reset, and to ground one input of the NAND circuit 27 at the time of set. The contact member 25 on the bellows 21 side is always grounded via the lead wire 26 and the terminal 11. 41 is a light emitting diode interposed between the collector of the transistor 37 and the power source. A light receiving element 42 constitutes a photocoupler together with the light emitting diode 41, and is connected in series to an AC power source 45 together with the bulb driving load 43 and a resistor 44. A triac 46, a series circuit consisting of a resistor 47 and a capacitor 48, and a varistor 49 are connected in series to the power supply 45, and the gate of the triac 46 is connected between the light receiving element 42 and the resistor 44. Note that this intake control circuit is similar to the above-mentioned intake control device 4.
It is provided every 4d from a to 4d.

Next, the effect will be explained.

First, in the intake control circuit shown in FIG. 3, when the power is turned on and the reset switch 40 is switched to the set side from a stopped state in which the reset switch 40 is resetting the above flip-flop circuit, the output of the NAND circuit 27 becomes The signal rises from "0" to "1", and the output of the inverter 28 becomes "0". This output is applied to a timer circuit 31 via a differentiating circuit to generate a positive pulse of, for example, 2 seconds. This pulse passes through the bypass circuit 39, drives the transistor 37, turns on the light emitting diode 41, reduces the resistance of the light receiving element 42, causes a large gate current to flow through the triax 46, causes current to flow through the drive load 43, and causes the intake air to flow. Each valve in the control devices 4a to 4d is opened. By opening this valve, the suction operation by the suction source 1 is started, and the workpieces brought close to each of the suction pads 5a to 5d are sucked. At this time, if the adsorption is complete, the pressure inside the passage 7a of the body 7 shown in FIG. 2 will also become negative.
The bellows 21 contracts to the left, separating the contact member 25 from the contact member 20. On the other hand, the timer circuit 3
For example, the output of 1 returns from the level of ``1'' to ``0'' after two seconds have elapsed, and thereafter the transistor 37 is not driven by the bypass circuit 39. However, when the contact member 25 separates from the contact member 20, the two inputs of the NAND circuit 32 are
"1" and "1" and the flip-flop
A signal "1" is obtained at the output of the NAND circuit 33, which continues to drive the transistor 37, the valve continues to be opened, and the workpiece 6 is maintained at suction by the suction pads 5a to 5d. Therefore, the workpiece 6 can be moved arbitrarily. On the other hand, to stop the adsorption, turn the reset switch 40 on the flip-flop's NAND circuit 34.
By switching to the reset input terminal side of the NAND circuit 33, the output of the NAND circuit 33 becomes "0", and by opening the transistor 37, the current supply to the driving load 43 of the valve is stopped and the valve is closed.

On the other hand, if one or more of the suction pads 5a to 5d does not come into close contact with the workpiece 6 before the two seconds set by the timer circuit 31 elapse, resulting in incomplete suction, and external air is sucked in. ,
Before that 2 seconds have elapsed, the bellows 21 does not move to the left in FIG. 2, and after once moving to the left, the bellows 21 returns to the right in FIG. 2, and the contact members 25 and 20 Because they come into contact with each other,
As a result, the input signal to the NAND circuit 32 is "0"
Therefore, the output of the NAND circuit 32 becomes "1",
The output of the flip-flop NAND circuit 33 remains at "0". Therefore, when two seconds have elapsed, the drive of the transistor 37 is stopped, the current that drives the triax 46 via the photocoupler is stopped, the supply of current to the drive load 43 is cut off, and the valve is closed, corresponding to this valve. Intake from the suction pad is stopped. However, if the suction pads 5a to 5d become incompletely suctioned after 2 seconds have elapsed from the start of normal operation, both of the two input signals of the NAND circuit 32 have already become "1" before 2 seconds have elapsed. Since the set input of the NAND circuit 33 is "0", the output of the NAND circuit 33 remains "1" even after 2 seconds have elapsed, so the transistor 37 continues to be driven. That is, when the suction pads 5a to 5d lift the workpiece 6 for a certain period of time, that state is maintained continuously, thereby preventing the workpiece from falling suddenly.

As described above, in the case where a plurality of suction pads are provided from one suction source, even if incomplete suction occurs in any of the suction pads, the suction capacity of the other suction pads can be improved. It is constructed so that the suction action does not drop, and even if incomplete suction occurs after suction, the suction action does not stop, ensuring efficient suction holding and transport of the workpiece. It is something that can be done.

[Brief explanation of the drawing]

The drawings show one embodiment of a device for carrying out the present invention, with FIG. 1 being an explanatory diagram showing its outline, FIG. 2 being a sectional view of a vacuum switch device, and FIG. 3 being an intake control circuit diagram. 1... Intake source device, 5a to 5d... Suction pad, 6... Work, 20, 25... Contact member, 3
1... Timer circuit, 33, 34... NAND circuit of flip-flop circuit, 40... Reset switch, 45... AC power supply.

Claims (1)

[Claims] 1. In a work suction device in which an appropriate number of suction passages branched from a single suction source are each provided with a valve having a vacuum switch and a suction pad, the degree of vacuum in each suction passage is detected,
If incomplete adsorption occurs in any suction pad before the predetermined time, the valve in the intake passage is closed to move, and if incomplete suction occurs in any suction pad after the predetermined time, the suction is stopped. A work adsorption control method characterized by continuing air intake with a valve in a passage open.