GB2239677A

GB2239677A - Safety apparatus for an industrial robot

Info

Publication number: GB2239677A
Application number: GB9025941A
Authority: GB
Inventors: Won Yong Choi
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-11-19
Filing date: 1990-11-29
Publication date: 1991-07-10
Also published as: KR920005146B1; GB9025941D0; CN1052724A; JPH0379288U; IT1242174B; IT9048531A0; CA2031102A1; DE4032732A1; FR2654970A1; IT9048531A1

Abstract

A safety apparatus for a robot comprises a safety device (8) in the form of a two-port two-position switching valve installed between a filter (4) and a direction switching device (5) controlling a force generating device (7) of the robot. The safety device allows the supply of pressure medium to the direction switching device or cuts it off and discharges pressure medium from the force generating device (7). If a number of individual robot arms are to be controlled, operation of the safety device may cause several force generating devices to be stopped. <IMAGE>

Description

1 :2:2:3 'S; e' -7 -7 1 SAFETY APPARATUS FOR AN INDUSTRIAL ROBOT The

invention relates to the provision of an industrial robot used in any industrial processing line of a Factory Automation System and particularly to the provision of a safety apparatus for stopping the operation of an industrial robot in the event of an emergency or accident for safety purposes.

Various industrial robots for Factory Automation Systems in industrial processing lines have been developed. One example is that of a robot arm reciprocates within a limited distance using a power driven source, such as a pneumatic pressure system lor ari oil pressure system, so as to automatically perform a predetermined working procedure. 15 There is the disadvantage that accidents or emergency situations have often happened when a worker has inadvertently moved into the working space of a robot arm of an alien substance has been introduced into the working or a robot arm unintentionally during the operation of the robot. 20 A typical example of this problem in the conventional apparatus will be described in detail with reference to Fig. 1 which shows a pressure medium circuit used in a drive control apparatus of a robot arm. The circuit is constructed so that the pressure generated at an air compressor or oil pressure generating device 1 pushes the pressure medium stored in storage vessel 2 out and the oil vented under a predetermined pressure therefrom is passedn sequence through pressure adjusting device 3, oil filter 4 and direction switching device 5 and then operates drive device 7 f or driving a robot arm. Pressure adjusting device 3 makes uniform the pressure of oil introduced thereunto, oil filter 4 gets rid of impurities contained in the sure medium, and direction switching device 5 is a type of three-port twoposition switching valve to allow pressure medium to be supplied to both ends of drive force generating device 7 through circuit elements 6A and 6B or to be removed therefrom. Therefore, the reciprocation of power transferring member 7A in drive force generating device 7 makes it carry out a 1 2 predetermined amount of work on load W connected to the f ront end of power transferring member 7A.

Suf f icient saf ety cannot be assured as the system is not equipped with a braking device f or stopping the running of the mechanism while it is in operation. That is, accidents may happen when abnormal situations existed in the working area.

Also, a robot is normally provided with a plurality of arms performing similar or different working procedures controlled by means of a single control device mounted on the robot. At the time when a predetermined operation is performed using some of the arms it is not possible to operate only the arms required; all arms are operated giving an unnecessary power consumption. When any arms or parts of arms"are ' out of order, it is not possible to stop only the arms requiring repair from running during operation. Repair work is made troublesome because all mechanisms of a robot must be stopped, including arms which do not require repair, and thus productivity is decreased.

The object of the invention is to provide a safety apparatus for an industrial robot which leads to greater safety and operational efficiency, and higher productivity as well a allowing independent operation of parts of arms, thereby reducing the power consumption and permitting arms that require repair to be repaired during the operation of a robot.

P The invention provides a safety apparatus of an industrial robot comprising an intermittent safety means in the form of a two-port two-position switching valve, installed between a filtering means and a direction switching means of a pressure medium circuit, for cutting off a pressure medium being supplied to a drive force generating means on the basis of a signal from a drive stopping control member when an abnormal situation occurs at or near a power transferring member, and for automatically discharging pressure medium received in a drive force generating device to stop the operation of the drive force generating means, thereby preventing the occurrence of accidents and enhancing safety, operational efficiency and productivity.

1 3 The invention also provides a safety device for an industrial robot comprising a supply chamber, in communication with a means for supply of pressure medium, a discharge chamber provided with an exit passage for pressure medium, a stop mechanism, a connection means by which either on e or the other of the supply or discharge chamber can be placed in communication with a f orce generating device of an industrial robot such that a pressure medium can pass between them, and a control mechanism f or the connection means such that when the stop!'- mechanism is actuated, the control mechanism breaks communication between the f orce generating device and the supply chamber, and imposes communication between the force generating device and the discharge chamber. A specific embodiment of the invention is described in detail below, by way of example, with reference to the accompanying drawings, in which: 20 Fig. 1 is a schematic view illustrating a pressure medium circuit used in a drive control device of a conventional industrial robot; Fig. 2 is a schematic diagram of a pressure medium circuit used in a drive control device of an industrial robot provided with a safety device, according to an embodiment of the invention; and Fig. 3 is an electrical circuit of a safety device according to the invention.

Fig. 2 and Fig. 3 show a pressure medium circuit used f or drive control of a robot arm for a Factory Automation system in industrial processing.

Pressure generating device 1 generates the pressure f or discharging a pressure medium, such as air or oil, for example, at some predetermined pressure. The pressure generated by device 1 pushes on the pressure medium stored at storage vessel 2 forcing it to pass through pressure adjusting device 3 and filtering device 4. Filtering device 4 removes any alien 4 substances contained in the pressure medium to supply only pure pressure medium through safety device 8 to a direction switching device 5, in this case a three-port two position valve. Direction switching device 5 can supply pressure medium to or receive it from drive force generating device 7, or device 5 can cut off the supply of pressure medium. Pressure medium is circulated by use of circuit elements 6A and 6B, each connected near an end of drive force generating device 7. Power transferring member 7A is mounted slidably in drive force generating device 7 and is reciprocated as a result of the flow of the pressure medium to perform a predetermined working apparatus on load W over a predetermined travel distance.

Safety device 8 is connected by' means of circulating members 6 between filtering device 4 and direction switching device 5 either to supply pressure medium to direction switching device 5 or to cut it off and discharge pressure medium from this mechanism.

Safety device 8 is in this case a two-port two-position switching valve as shown in Fig.3, the valve of which is moved up and down by operation of a stop mechanism Pl, such as a switch, an electromagnetic member being energized by the coil current of safety device 8. This device 8 starts its operation with actuation of start mechanism P2, in this case also a switch. At that time, an operating control member RY, such as for example a relay, is in operation to connect operating control opening/closing members RYS1 and RYS2 to a power source. Thus, supplying passage 8A and discharging passage 8B formed in the body of safety device 8 are selectively communicated with circuit element 6 or crossed to each other, so that pressure medium may be supplied to drive force generating device 7 or cut off thereto.

The device of the invention comes into action when operating start member P2 is connected. Thereafter, operating control member RY is operated to connect operating control opening/closing members RYS1 and RYS3 to a power source, while safety device 8 is operated to connect supplying passage 8A to circuit element 6. Thus, pressure medium is fed into drive force generating device 7 to perform the work of a robot arm.

CI 1 In contrast, if an abnormal situation occurs at the load side of drive force generating device 7, operating stop mechanism P1 is operated to break off the connection of operating control opening/closing members RYSI and RYS2 to a power source. At that time, safety device 8 is interrupted from a power source to be initialized. That is, circuit element 6 for guiding pressure medium is connected to discharge passage 8B; passage of pressure medium into pressure generating device 7 is blocked, as shown in Fig. 2, while the medium discharges through discharging passage 8B. In this case, oil is returned to storage vessel 2.

Thus, drive force generating device 7 is stopped at its Point of operation, thus preventing danger to the user, hereby enhancing user safety. The is also the effect that an alien substance on the side of load W which causes abnormal operation of the mechanism of a robot does not, however, break any operating members mounted on the work performing side, thus further heightening safety in working of a processing line.

It is known that a robot is normally equipped with a plurality of arms. Therefore, embodiments of the invention can be used to operate individual arms in such a way as to control the safety device 8 to stop some of the driving force generating devices 7, when accidents have happened or an abnormal situation has occurred. Such a system is easier to maintain as repair and replacement of parts is simpler.

Control of operation allows only those drive force generating devices 7 required to be operated; this can reduce the power consumption of the whole mechanism.

6 1

Claims

1. A saf ety apparatus of an industrial robot comprising an intermittent safety means in the form of a two-port twoposition switching valve, installed between a filtering means and a direction switching means of a preA;sure medium circuit, for cutting of f a pressure medium being supplied to a drive force generating means on the basis of a signal from a drive stopping control member when an abnormal situation occurs at or near a power transferring member, and for automatically discharging pressure Medium. received in a drive. force generating device to stop the operation of the drive force generating means, thereby preventing the occurrence of accidents and enhancing safety, operational efficiency and productivity.

2. A safety device for an industrial robot comprising 20 a supply chamber, in communication with a means for supply of pressure medium, a discharge chamber provided with an exit passage for pressure medium, a stop mechanism, 25 a connection means by which either one or the other of the supply or discharge chamber can be placed in communication with a force generating device of an industrial robot such that a pressure medium can pass between then, and a control mechanism for the connection means such that when the stop mechanism is actuated, the control mechanism breaks communication between the force generating device and the supply chamber, and imposes communication between the force generating device and the discharge chamber.

3. A safety apparatus for an industrial robot as herein described with reference to Fig. 2 and Fig. 3 of the accompanying drawings.

Published 1991 at The Patent 0171ce.Statr House, 66/71 High Holbom, London WCIR47?. Further copies rnay be obtained from Sales Branch. Unit 6. Nine Mile PoinL Cwmfelinfach. Cross Keys. NewporL NPI 7HZ. Printed by Multiplex techniques lid, St Mary Cray. Kent.