SE465067B - Production-adapted safety system - Google Patents

Abstract

Production-adapted safety system for at least one automatically operating production unit 11, for example a robot. The system includes at least one safety circuit in which there is at least one safety device 10, for example in the form of an edge protector, a surface protector, a holder device 29, etc. The production unit 11 is controlled by a computer 32 or the like. Each safety device 10 is connected to at least one input of a safety module 28 comprising twin stop relay circuits A, B and monitored for short circuits and interruptions. Arranged parallel to the stop circuits A, B there is a re-set relay circuit C which is provided with a re-set device 31 which has to be both closed and opened before the outputs from the twin stop circuits are closed. <IMAGE>

Description

465 10 15 20 25 30 35 067 2 The second a safe stop of the robot with a simple and quick restart option.

The protective stop presupposes the robot, is equipped with brakes, which slow down the system. where all power reaches the emergency stop button without risk of damage to the machine or product. the stop function level is a protection stop, ie. that the production unit, ie.

The third stop function level is emergency stop, which can cause dangerous function is broken, pressed. In this case, there is no requirement for a quick and easy restart.

Several different types of protection devices, e.g. border protection and A production stop can e.g. switch to a protective stop if any surface protection provides different types of stop functions. opens a pre-locked safety gate.

When building circuits for personal safety in machines and protective devices, it is required that a large number of components cooperate to meet the requirements. This means that availability becomes worse and that the technical possibilities of using the control system in a way that is desirable from a production point of view are reduced.

OBJECTS OF THE INVENTION ocu vrx-rrcns-rr: CHARACTERISTICS The object of the present invention is to provide a reliable safety structure, where several machines and protective functions can be connected. Thus, the structure should be simple, easy to understand and its function should be clear. Troubleshooting should be easy to perform and defective components should be easy to replace. Furthermore, you do not need to be a security expert to be able to check and understand the connection. The safety structure must also not affect production control in a negative direction, it must be production-adapted. These tasks have been solved by arranging in parallel with the stop circuits (A, B) a return which is provided with a reset which must have both been closed and opened the scaffold relay (C), actuator (31), ß ~ <7 \ UH (ID <3 \ ~ J 3 before closing the outputs of the then doubled stop circuits.

DESCRIPTION OF THE DRAWINGS The invention will be described in more detail below in an exemplary embodiment with reference to the drawings.

Fig. 1 shows a plan view of a work area within which a robot operates.

Fig. 2 shows a circuit diagram of a safety circuit included in a safety module according to the invention.

Fig. 2a shows a reset relay circuit for a security module according to the invention.

Fig. 3 shows a greatly simplified diagram of the interconnection of a security module with a computer.

Fig. 4 shows a diagram of how different protection devices can be connected to different machines.

Fig. 5 shows the interconnection of two modules for expanding the protective stop outputs.

DESCRIPTION OF EMBODIMENTS Figure 1 shows an example of a working area for a robot II surrounded by various protection devices 10. The outermost protection device 10 consists of a fence 12, in which a gate 13 and a gate 14 are arranged, through which the objects 15 transported, to be processed by the robot ll. 16 denotes a station changer, equipped with two positioners 17 and 18, which can be made to change position. On one positioner 17 is placed - attached - a workpiece 15, which work operation is performed within a service area, 19, which is bounded by a light beam 20, which is generated by a light source 21 and detected by a photocell 22 via mirrors 23. Inside the light barrier 20 is provided with a contact mat 24, which is likewise included in the protection system.

The robot 11 itself is located within a machining area 25, which is surrounded by a light screen 26. Inside the fence 12, a control unit 27 is also arranged, which contains a number of protection modules 28 corresponding to the number in the protection system. Inlet protection devices 10. The control unit may also comprise a three-position holding device 29 and outside the fence a start button 30 and a reset device 31. Inside the fence a robot control unit 32 is further arranged, which comprises a computer which controls the robot's work program and possibly a process unit 33 for controlling the work process.

The fence 12 indicates the outer protection limit and if the gate 13 or gate 14 is opened, two switches a and b are actuated (Fig. 2) so that double protection circuits A and B are broken and a controlled production stop is initiated. The robot's computer program describes how a stop can be made without risk of damage to the machine and product. Normally, production stoppage means that the work process, e.g. a welding process, is completed before a stop is allowed.

A protective stop is triggered even if the light barrier 20 is passed and the contact mat 24 is stepped on. This protection function stops the unit moving in this area, ie. in Fig. 1 the station changer 16. As long as the operator is within this risk area, ie. on the contact mat 24, the positioners 17 and 18 must not be able to change places. When passing the light curtain 26, ie. when entering the processing area 25, protective stops are triggered, which stop the entire production section. With the aid of a holding device 29, the stop functions can be switched off, for example to find out the causes of operational disturbances, to study the production cycle or the like.

Each protection device 10, i.e. the gate 13, the gate 14, the contact mat 24, the light barrier and light curtain arrangement 20, 26 and possibly holding devices 29, are each connected to a respective protection module 28 which in turn is included in the control unit 27.

Fig. 2 shows an example of a wiring diagram for a safety circuit, which is included in a protection module 28. In order for the relays k1 and k2 in the stop relay circuits A and B to be activated, the switches a cx fl l b be closed and the "input" of the reset device 31 both closed and opened. Only then are the doubled outputs A1 and B1 resp. A2 and B2 etc .. A short circuit between the terminals a and b of the switches does not give a dangerous function.

This means that a fault can only lead to an output not breaking when the protection device gives a stop signal to the control unit. This error also means that it is not possible to reset the protection device again.

With reference to Fig. 2a, the reset process takes place as follows: In a first step, the contact in the reset device 31 is closed. If the two stop relays K1 and K2 have fallen, the current passes the coil of relay K4. Relay K4 pulls and thereby capacitor cl is charged. In a second step, the contact in the reset device 31 is opened by resilience whereby K4 falls. Thereby, energy goes to the relay's K3 coil which draws as long as the energy in cl is sufficient. During the time that the relay K3 pulls, the relays K1 and K2 have time to pull and take self-holding, i.e. provided that inputs a and b are closed.

A control unit can also have a short-circuit-protected input.

In this case, it is connected to the contact mat. When standing on the carpet, the input is short-circuited, giving a stop signal.

In order for the control unit to give a clear signal, a reset must be performed and the line to the input, ie. the loop be closed over a resistor connected parallel to the mat.

Interruptions change the potential and cause a stop signal.

If one of the relays kl, k2, k3 or k4 gets stuck in the pulled position, a new start cannot be obtained. Because the inputs have different potentials, an incorrect connection only gives a stop signal.

Ld1 and ld2 are optocouplers which provide a stop signal before the relays k1 and k2 fall. This signal is connected directly to the robot controller 32's computer which has the chance to stop before kl and k2 give a stop. K1 and k2 can also be delayed in a safe way by connecting external capacitors.

Automatic reset can be obtained by switching a pulse circuit over the reset device 31.

If more relays are desired to be connected to the outputs, these can be monitored in the test input. The monitoring means that a new start will not be possible unless the extra relays have fallen first.

The described safety circuit provides protection against incorrect connection, protection against short circuit, production stop, safe delay of stop time and.manual and automatic reset.

Figure 3 shows the simplicity of the connection of the security module 28.

The components that affect safety are connected to the computer 34 via the safety module 28. Normally all control goes through the computer but at a stop signal from the protection device 10 the stop signal goes directly to the "dangerous" functions.

Production stop can be used for information to the computer or for a quick stop signal. Production stoppage is a possible addition to the modules.

The outputs are here connected to valves 35 and the electric motor 36. They can be doubled in series or with a breaking contact.

Figure 4 shows how easily different protection devices 10, e.g. the contact mat 24 and the light barrier 20 are connected to various machines 37a, 37b, 37c, which are not stopped by all the protection devices.

It is also shown here how easy time modules 38 and 39 for jumpering of protective devices are connected. For module 39, it also applies that it is monitored every time a protection device has been affected, ie. outside the jumper period. Both entrances. must fall 455 os? 7 before the control module can be reset. Module 38 needs its own automatic monitoring or through a test inlet in the protection device that it locks.

Figure 5 shows how easily the number of safe outputs can be increased with an additional module that has automatic reset.

Claims (3)

465 067 10 15 20 25 8 PATENT REQUIREMENTS 1. l. Device for production-adapted protection systems for at least one automatically operating production unit (ll), e.g. a robot, and in which system at least one protection stop circuit is included, in which at least one protection device (10) is arranged, e.g. in the form of a boundary guard, a surface guard, a holding device (29), etc., the production unit (II) being controlled by a computer (32) or the like, each guard device (10) being connected to at least one interrupt-monitored guard module (28) comprising dual stop relay circuits (A, B), characterized by a short-circuit and input to a resetting relay circuit (C) arranged in parallel with the stop circuits (A, B), which is provided with a reset device (31), which must have both been closed and opened before the outputs of the duplicate stop circuits are closed. Device according to Claim 1, characterized in that an optocoupler (Ld1, Ld2) is arranged in each stop circuit (A, B), which is located in the circuit in such a way that it emits a stop signal to the computer before the relays K1 resp. . K2 in the stop circuit drops. J Device according to claim 1, characterized in that in the stop relay circuit (A and / or B) delay means are arranged for delaying the stop signal to control units and prioritizing the stop signal to the computer.