Patent Application
20060114323
The present invention relates to a method and an apparatus for safeguarding hazardous areas in machines. Such a hazardous area is monitored by at least one sensor that is suitable for identifying objects penetrating into the hazardous area and is connected to a machine control system.
Methods and protective apparatus are known with which machines can be safeguarded. It is accordingly possible to draw a distinction between permitted and non-permitted penetration of specific objects. An apparatus of that type which is disclosed by U.S. Patent Application Publication No. US 2003/0164447 A1 safeguards the hazardous area of a metal-processing machine. In that case, the opening to the hazardous area of the metal-processing machine is initially safeguarded through the use of a light barrier. The light barrier is capable of distinguishing between the penetration of permitted workpieces and forbidden body parts of the operating personnel. The distinction is drawn in that the workpieces, as they pass through the light barrier, darken only one light beam because of their low thickness, while the limbs of the operating personnel, due to their larger dimensions, darken at least two lights beams beside each other. As long as only one light beam is darkened, the metal-processing machine remains in the quite normal operating state, whereas when body parts of the operating personnel penetrate, the machine is switched off immediately.
However, in the case of hazardous areas in printing presses, such a type of safeguard is not expedient since there, in the area of the delivery and of the feeder of a sheet-fed printing press, under specific conditions, it is necessary for the operating personnel to reach into the hazardous areas during the operation. However, such a penetration is not permitted by the apparatus according to the prior art.
It is accordingly an object of the invention to provide a method for state-dependent safeguarding of hazardous areas of machines and an apparatus for implementing the method, which overcome the hereinafore-mentioned disadvantages of the heretofore-known methods and apparatus of this general type, which are capable of distinguishing between permitted and non-permitted penetrations into the hazardous area and which also permit the penetration of actually non-permitted objects into the hazardous area under specific conditions.
With the foregoing and other objects in view there is provided, in accordance with the invention, a method for safeguarding hazardous areas in machines, which comprises monitoring a hazardous area with at least one sensor for identifying objects penetrating into the hazardous area. The at least one sensor identifies when an object penetrates into the hazardous area. A machine control system communicates with the at least one sensor. The machine control system acts on the state of the hazardous area of the machine on the basis of the identification and the respective operating state of the machine.
With the objects of the invention in view, there is also provided an apparatus for safeguarding hazardous areas in machines. The apparatus comprises at least one sensor monitoring the hazardous area for identification of objects penetrating into the hazardous area. The at least one sensor identifies when an object penetrates into the hazardous area. A machine control system communicates with the at least one sensor. The machine control system acts on the state of the hazardous area of the machine on the basis of the identification and the respective operating state of the machine.
In order to safeguard hazardous areas in machines, such areas are monitored by a sensor which is capable of identifying objects penetrating into the hazardous area. It is therefore in principle possible to distinguish between objects which may penetrate into the hazardous area and forbidden objects. The permitted and forbidden objects are divided into two classes for this purpose, such that each identified object falls into either the permitted or the forbidden class. As long as a permitted object penetrates into the hazardous area such as, for example, when a new sheet stack is introduced into the feeder, the machine continues to run quite normally. If a non-permitted object penetrates into the hazardous area then, according to the prior art, the machine would be switched off immediately. According to the present invention, however, the operating state of the machine is now also taken into account appropriately, so that the machine is actually switched off only when, due to the current operating state, there is also an acute risk to the operating personnel in the hazardous area of the machine. For instance, if movable parts in the hazardous area which represent a crushing hazard for the operating personnel are stopped in any case due to the current operating state, the machine itself does not have to be stopped. The protective apparatus therefore always takes into account the acute potential for injury to the operating personnel and takes the machine out of operation only when the potential for injury in the hazardous area is also actually there. This increases the availability of the machine.
In accordance with another mode of the invention, the sensor is suitable for distinguishing between human body parts and objects. With this refinement of the invention, it is ensured that, in the case of an acute risk in the hazardous area in the event of penetration of human body parts, the machine is immediately changed to a safe state, while the introduction of objects, such as during a stack change in the feeder or delivery of a printing press, does not trigger a machine stoppage.
In accordance with a further mode of the invention, three-dimensional scanning of the object penetrating into the hazardous area is advantageously carried out through the use of the sensor. Such a sensor is represented by a 3-D camera, which permits the penetrating object to be identified unambiguously due to its external shape. Through the use of such a 3-D camera, it is also possible to register the penetration depth of the penetrating object as well, so that the machine is only shut down when the object has penetrated into the hazardous area to such an extent that there is an immediate risk. In addition, in this way, depending on the respective operating state of the machine and the different potential hazards resulting therefrom, different penetration depths for different objects can be permitted. In this case, further classes can be added to the two classes of permitted and non-permitted objects. In those further classes, the permitted and non-permitted objects are further divided up in relation to their penetration depth as a function of the respective machine state. For instance, in the feeder area, in the case of a stack carrier board with the remainder of a stack which is located in the upper area, the lower area can be cleared for the operating personnel to enter until the stack carrier board moves down again. If the downward movement of the stack carrier board is initiated, the machine is in another operating state again, which effects the immediate shutdown of the machine should operating personnel still be found underneath the stack carrier board of the feeder stack.
In accordance with an added, simplified mode of the invention, the sensor is a light barrier or a light curtain. In this case, a light curtain is understood to mean a plurality of light barriers disposed in one plane. With these light barriers, it is also possible to perform at least coarse division between permitted and non-permitted objects. Of course, during the use of the light barriers, care must be taken to ensure that objects and human body parts are always kept satisfactorily away from one another, so that the human body parts are always assigned to the non-permitted objects.
In accordance with an additional mode of the invention, the machine control system acts on hazardous parts of the machine in the hazardous area. In this case, is not necessary for the entire machine to be stopped if a non-permitted object has penetrated into the hazardous area. Instead, the hazardous parts of the machine giving rise to the risk of injury are either stopped or brought into a safe state, so that the non-permitted object can no longer come into contact with the hazardous parts and in this way is protected against injury.
In accordance with yet another mode of the invention, the safeguarding of the hazardous area is carried out through the use of the machine control system acting on the basis of the penetration movement of the identified object determined through the use of the sensor. Through the use of the sensor, it is possible to register the movement of the object penetrating into the hazardous area. If the object moves toward the hazardous parts of the machine, then the machine must be switched off or put into a safe state. However, if the direction of movement of the object should change before the occurrence of an acute risk of injury so that the movement leads away from the hazardous parts of the machine, then the machine does not have to be switched off and instead can continue to run.
In accordance with yet a further mode of the invention, in addition to the direction of movement, the speed of penetration of the identified object can also be taken into account. If the object penetrates into the hazardous area at high speed, the hazardous parts of the machine or the entire machine have to be switched off correspondingly faster than if the object approaches at a slower speed. The reason for this is that, even in the case in which the machine is switched off immediately and in the event of any braking of the moving hazardous parts which may be carried out, a certain run-on and braking time as well as a reaction time due to the inertia of rotating masses or moving masses in the machine have to be taken into account.
In accordance with a concomitant mode of the invention, the safeguarding of the hazardous area is carried out by the machine control system acting on the basis of the shape of the identified object detected through the use of the sensor. It is possible, for example, to distinguish between objects and human limbs by using the shape of the identified object. In addition, objects can also be divided up into different classes so that, for example, the introduction of a stack into the feeder of a sheet-fed printing press is permitted, but the intentional introduction of a tool by the operating personnel is also detected and leads to a stoppage of the machine. In this case, the operating personnel are not only protected against hazards which can occur when tools encounter moving parts of the machine, for example as a result of the tool being thrown out, but at the same time the mechanism of the machine, which could otherwise be jammed as a result of the introduction of the tool, is also protected. In this case, the protective apparatus therefore serves not only to protect the operating personnel but also to protect the machine.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and the invention is described herein as embodied in a method for state-dependent safeguarding of machines and an apparatus for implementing the method, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
Referring now to the figures of the drawings in detail and first, particularly, to
On one hand, both the sheet feeder 11 and the sheet delivery 1 constitute a considerable source of hazards, since there is a considerable risk of injury to the operating personnel due to the moving components. On the other hand, the hazardous areas in the interior of the sheet feeder 11 and the sheet delivery 1 cannot simply be blocked completely against interventions by mechanical protective apparatus, since certain interventions are required in order to operate the printing press 10. For example, in the sheet feeder 11, after the feeder stack 14 has been used up, an empty pallet must be removed and a new feeder stack 14 introduced. The feeder stack 14 can be changed during continuous operation in order not to interrupt the operation of the printing press 10. This is similarly true of the delivery 1, at which the delivery stack 13 with the printed sheets has to be removed at specific time intervals in order to create space for new incoming printed sheets 17.
In addition, the operating personnel must be provided with the possibility of performing inspections of the printed image on the sheet 17 in the delivery stack 13 at specific time intervals. For this purpose, individual sheets 17 are normally removed from the delivery stack 13 by the operating personnel and assessed on a test bench. It must therefore be possible, during the operation of the printing press 10, to reach at least into specific regions of the feeder 11 and of the delivery 1. For safety reasons, however, the hazardous areas in the feeder 11 and in the delivery 1 must be safeguarded appropriately.
In addition, the operating state of the machine 10 is also taken into account. For example, a penetration location 3 in the vicinity of the gripper chains 15 only constitutes a hazard when the gripper chains are also moving. If no sheets 17 are being conveyed, the gripper chains 15 are stationary and a penetration location 3 in the vicinity of the gripper chains 15 does not lead to a hazardous situation for operating personnel penetrating there, for which reason a machine stoppage is not necessary in this case.
In an alternative refinement, provision can also be made for only the gripper chains 15 in the delivery to be switched off, if they have a separate drive. If the machine control system 5 cannot detect any immediate hazard to the operating personnel on the basis of the penetration location 3 determined by the sensor 40, an acoustic or visual alarm can nevertheless be output in order to refer the penetration into the hazardous area to the operating personnel.
Instead of the sensor 40, a 3-D camera can also be installed, which monitors the cross section of the opening 2 and the interior of the hazardous area. The camera can determine the shape and therefore the identification of a penetrating object 8, 13 shown in
In an embodiment according to
This application claims the priority, under 35 U.S.C. ยง119, of German Patent Application 10 2004 055 229.0, filed Nov. 17, 2004; the entire disclosure of the prior application is herewith incorporated by reference.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2004 055 229.0 | Nov 2004 | DE | national |
