Abstract:
An intrusion detection system for altering the operation of an associated machine when an appropriate intrusion is detected, the system comprising: a first detector to detect the presence of a first distinguishing property and to selectively produce an intrusion signal when the first distinguishing property associated with an object is detected within a danger zone approximate a pinch point of a machine, wherein an area approximate the pinch point of the machine does not exhibit the first distinguishing property; and, a controller, operatively coupled to the intrusion detector and the machine, for controlling the operation of the machine, wherein the controller generates a corrective action signal directed toward the machine when intrusion signals are received from the intrusion detector.

Description:
REFERENCE TO RELATED APPLICATION  
       [0001]    This application claims the benefit of U.S. Provisional Application Serial No. 60/332,102, entitled “SAFETY-SHUTOFF DEVICE FOR A MANUALLY FED PROCESSING MACHINE”, filed on Nov. 21, 2001, the disclosure of which is incorporated herein by reference. 
     
    
     
       BACKGROUND  
         [0002]    1. Field of the Invention  
           [0003]    The present invention is directed to detection systems operatively coupled to safety control systems for process machines, and in particular, to detection systems operatively coupled to safety control systems for manually fed process machines having at least one pinch point that can cause serious bodily injury to a worker caught in such a pinch point.  
           [0004]    2. Background of the Invention  
           [0005]    Process equipment safety systems are well known in the prior art. Most notably, prior art safety systems for industrial machines utilize infrared light curtains or some other sort of light beam safety system. The light curtains are positioned to encircle the machine or, if the machine is rigidly protected on other sides, a light curtain is positioned approximate the area of the unprotected portion of the machine. More often than not, the light curtain is placed in positions where workers have to interact with the machines.  
           [0006]    An exemplary infrared curtain safety system comprises a series of infrared transmitters placed opposite a series of infrared detectors and aligned so that during operation of the safety curtain the infrared transmitters transmit infrared light directly to the infrared detectors. Thus, when activated, the transmitters transmit a beam of infrared light that is received by aligned detectors. When an object passes through the curtain, their corresponding detectors are no longer continuously detecting one or more beams of infrared light. This results in the safety system determining that someone or something has entered the work area of the machine. Several safety system responses are taught in the prior art. These responses include signals being sent to the controller of the machine to stop all motion of the machine or reverse the immediate motion of the machine.  
           [0007]    An example of such an interaction between a worker and a machine may be shown by way of a worker placing a piece of material in a stretch bender. After the piece is positioned on the stretch bender, the worker removes his body and any other materials hazardous to the operation of the stretch bender and finally activates the light curtain. Generally, a signal from the light curtain that all the detectors are in fact receiving infrared light from the transmitters is required before the stretch bender initiates its process. If the safety curtain for any reason indicates that a corresponding detector is not receiving one or more infrared or other light beams, the safety system considers startup of the stretch bender to be hazardous. Only after the obstructions from the light beams have been removed is the stretch bender authorized to begin its task.  
           [0008]    Other prior art safety systems have utilized infrared curtains in addition to other safety devices to provide a safety barrier around process machines. Most notably, prior safety systems have utilized one or more buttons that are depressed by a worker approximate the machine so that the worker and the worker&#39;s appendages are outside of the working zone of the machine. If one or more of these buttons fails to be depressed, an interrupt signal or some other corrective signals are sent to machine control unit to cease the movement of the machine and/or immediately reverse the previous movement of the machine. In addition, some prior art systems have utilized ultrasonic detection systems in addition to light curtains such that once the light curtain is pierced an interrupt signal to the machine is not automatic. The ultrasonic detector determines how close in proximity to the machine the object is that pierced the light curtain. If the object is dangerously close to the machine as determined by the ultrasonic detector, then an interrupt signal or other corrective action signal is sent to the machine.  
           [0009]    Finally, some additional safety systems have utilized infrared detectors that detect the placement of a human hand. The systems utilize infrared transmitters that transmit infrared light and bounce the infrared light off of the human hand where it is detected by one or more detectors. If the human hand is not completely stagnant for the requisite period of time approximate a safe location as designated by the particular device, the infrared beams of light will not be reflected in sufficient amount or direction to be detected by the infrared detectors. Thus, the safety system determines that the workers appendages may potentially be within the operating zone of the machine. This being the determination, if the machine has not already started up, it will not start up; and, if it has already started its process, it will cease continuation of that process.  
         SUMMARY  
         [0010]    The present invention is related to safety-shutoff devices for manually fed processing machines (such as alligator shears) and to methods for operating processing machines having a pinch point. In addition to alligator shears, such processing machines include, without limitation, other types of shears, slicers, shredders, grinders, and the like. Therefore, for the purpose of this application “pinch point” refers to any area of such processing machine that can cause injury to an operator&#39;s hand or appendage, such as areas near shear blades, slicer blades, shredders, rollers, electrical contacts, etc. The present invention is directed to detection systems that detect the presence of a unique property exhibited by a worker or apparel worn by the worker when within a safety zone approximate the pinch point, thereby instructing the safety control system to take corrective action. Also, the present invention is directed to detection systems that detect the presence of a unique property emanating or reflecting from a source and detected by a sensor coupled to a worker&#39;s appendage while the worker is within a safety zone approximate the pinch point, thereby instructing the safety control system to take corrective action.  
           [0011]    It is a first aspect of the present invention to provide an intrusion detection system for altering the operation of an associated machine when an appropriate intrusion is detected, the system comprising: a first detector to detect the presence of a first distinguishing property and to selectively produce an intrusion signal when the first distinguishing property associated with an object is detected within a danger zone approximate a pinch point of a machine, wherein an area approximate the pinch point of the machine does not exhibit the first distinguishing property; and, a controller, operatively coupled to the intrusion detector and the machine, for controlling the operation of the machine, wherein the controller generates a corrective action signal directed toward the machine when intrusion signals are received from the intrusion detector.  
           [0012]    It is a second aspect of the present invention to provide an intrusion detection system for altering the operation of an associated machine when an appropriate intrusion is detected, the system comprising: an alligator shear processing machine having a shear blade for shearing a feed material thereby creating a potential pinch point; a first detector to detect the presence of a first distinguishing property and selectively produce an intrusion signal when the first distinguishing property associated with an object is within a danger zone approximate the pinch point of the alligator shear processing machine, wherein the alligator shear processing machine and a feed material regularly coming into contact with the machine at the pinch point do not exhibit the first distinguishing property; and, a controller, operatively coupled to the intrusion detector to receive intrusion signals and operatively coupled to the processing machine to relay an operational signal for controlling the operation of the processing machine, wherein the controller generates a corrective action signal directed toward the processing machine when intrusion signals are received from the intrusion detector.  
           [0013]    It is a third aspect of the present invention to provide a method for safely operating a processing machine having a pinch point, the method comprising the steps of: detecting the presence of at least a first distinguishing property within a danger zone in close proximity to a pinch point of a machine, the first distinguishing property being a property not exhibited by the machine in an area approximate the pinch point; and, transmitting a corrective signal, to a controller operatively coupled to the machine, upon detecting the presence of the first distinguishing property within the safety zone.  
           [0014]    It is a fourth aspect of the present invention to provide a method for operating a processing machine having a pinch point that comprises the steps of: sensing the presence of at least a portion of a user&#39;s appendage in a zone approximate the pinch point; and, upon sensing the presence of the portion of the user&#39;s appendage in the zone, transmitting a shutoff signal to a control of the processing machine. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    [0015]FIG. 1 is a schematic diagram of a first exemplary embodiment of the present invention;  
         [0016]    [0016]FIG. 2 is a cross-sectional view of a shearing zone of a machine;  
         [0017]    [0017]FIG. 3 is a schematic diagram of a second exemplary embodiment of the present invention;  
         [0018]    [0018]FIG. 4 is a cross-sectional view of a shearing zone of a machine including a user wearing sensors in accordance with the second exemplary embodiment of the present invention;  
         [0019]    [0019]FIG. 5 is a schematic diagram of an alternate first exemplary embodiment of the present invention; and  
         [0020]    [0020]FIG. 6 is a schematic diagram of an alternate second exemplary embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0021]    The exemplary embodiments described herein relate to safety-shutoff devices and methods for process machines having a pinch point, for example, without limitation, an alligator shear processing machine. It will, of course, be apparent to those of ordinary skill in the art that the devices and processes disclosed herein may be useful for other types of processing machines having mechanisms that are dangerous to a worker&#39;s appendage, such as pinch points, shear blades, slicers, shredders, grinders, rollers, electrical contacts and the like, collectively referred hereinafter as “pinch points”. The devices and methods herein described are intended to be used in addition to, or even in place of, existing mechanical guards, restraints, and other devices that are intended to protect the operator from such pinch points. Many applications of the inventions described herein are intended to provide protection to a worker without creating other hazards to the worker, and are intended to prevent the worker from injury due to the worker&#39;s lapses and/or absence of safe practices, while not interfering with the proper use of the machinery. Nevertheless, it is to be understood that other objects and advantages of the invention may exist inherently. Therefore, it is not necessary to meet any stated object or advantage of the inventions described herein in order to fall within the scope of the inventions described herein.  
         [0022]    As shown in FIG. 1, an alligator shear machine  10  includes a frame  12  having a stationary shear blade  14  and a moving shear blade  16 , which is pivotable between point A and point B. A hydraulic cylinder  18  is coupled between the frame  12  and the shear blade  16 , activation of which causes the shear blade to move from point A to point B, thereby causing the cooperating shear blades  14 ,  16  to shear any object positioned therebetween. Obviously, the pinch point P created by the shear blades  14 ,  16  is dangerous to a worker&#39;s hands.  
         [0023]    Operation of the hydraulic cylinder  18  is controlled by a control  20 , which transmits control signals  22  to the cylinder  18 . Such control signals  22  may include “forward”, “reverse”, and “stop”. Foot pedals  24 ,  26  operated by the worker are used to send manual commands to the controller  20 .  
         [0024]    As shown in FIGS. 1 and 2, a sensor  28  is provided to detect a property unique from a zone  30  approximate the pinch point P and unique from materials being fed between the blades  14 ,  16  by the worker. If this unique property is detected in the zone  30  by the sensor  28 , the sensor transmits a signal  32  to the controller  20  directing the controller  20  to stop and/or reverse the operation of the hydraulic cylinder  18 .  
         [0025]    The unique property detected by the sensor  28  in the zone  30  may be a magnetic property, a thermal energy property, an optical property, or an electromagnetic property. Exemplary optical properties include, but are not limited to, visible light and visible light reflected in the presence of a non-visible light source such as, for example, ultraviolet light. Exemplary electromagnetic properties include, but are not limited to, radio waves, microwaves, infrared waves, ultraviolet light waves, and X-rays. In this first exemplary embodiment, the worker will be wearing a glove  34  that exhibits a unique optical property; the glove  34  reflects green light in the visible spectrum. This unique property is detected by an optical sensor  28 , which in this exemplary embodiment is a video camera having appropriate light filters to detect only the presence of green visible light. Therefore, when the worker&#39;s glove  34  enters the zone  30  the sensor  28  will be operative to transmit the signal  32  to the controller  20 , directing the controller to stop and/or reverse advancement of the shear blade  16 . Optionally, the sensor  28  may be operative to transmit continuous signals  32  to the controller  20 , directing the controller to stop and/or reverse advancement of the shear blade  16  so long as the unique property is within the zone  30 . In such an exemplary system, the lapse of signals  32  to the controller  20  would enable normal operation of the shear blade  16  by way of operation of the foot pedals  24 ,  26 . It is also within the scope of the present invention that this unique property may be exhibited by transponders carried in or on the gloves or wristbands worn by the worker so as to emit the unique property.  
         [0026]    The sensor  28  may be mounted to the machine  10 , such as shown in FIG. 1, for example, or may be mounted remote from the machine. One example of a remote mounting of the sensor  28  involves positioning the sensor above the machine  10  (i.e., suspending it from the ceiling) so that it points downwardly towards the zone  30  approximate the pinch point P. This remote positioning above the machine would reduce any effects of machine vibration on the sensor  28  and may reduce the chance that the worker&#39;s hands/gloves  34  may be obscured by the materials being directed toward the pinch point.  
         [0027]    It is also within the scope of the invention to provide a visual indication of the zone  30  to the worker. This visual indication of the zone  30  may be provided by a light beam illuminating the zone  30 , for example, or by colored tape applied next to the pinch point, for example.  
         [0028]    As shown in FIGS. 3 and 4, in a second exemplary embodiment, sensors  36  are carried on a worker&#39;s hand, by way of the worker&#39;s glove  34 , that are adapted to detect a property unique to the zone  30 . For example, a device  38  may be used to create a magnetic field in the zone  30  and the sensors  36  may include inductive coils for sensing this magnetic field created by the device  38  when the sensors  36  enter the zone  30 . Alternatively, the device  38  may create an optical property in the zone  30  and the sensors  36  may be optical sensors adapted to sense this visible light created by, or reflecting from, the device  38  in the zone  30 . As with the first exemplary embodiment, magnetic properties, thermal energy properties, optical properties, and electromagnetic properties may emanate or reflect from the device  38  such that the sensors  36  are adapted to send a signal  32  to the controller  20 , instructing the controller to send an emergency stop command and/or reverse command to the hydraulic cylinder  18  operating the moveable shear blade  16  whenever such a property is detected and/or in a sufficient amount/magnitude. Optionally, the sensors  36  may be operative to transmit continuous signals  32  to the controller  20 , directing the controller to stop and/or reverse advancement of the shear blade  16  so long as the unique property is within the zone  30 . In such an exemplary embodiment, the lapse of signals  32  to the controller  20  would enable normal operation of the shear blade  16  by way of operation of the foot pedals  24 ,  26 .  
         [0029]    Referencing FIG. 5, it is also within the scope of the invention to have an alternate first exemplary embodiment that provides a second sensor  40  to detect a second distinguishing property unique from the zone  30  approximate the pinch point P and unique from materials being directed toward the blades  14 ,  16  by the worker. This second sensor  40  may also detect a magnetic property, a thermal energy property, an optical property, or an electromagnetic property. The second detector may be operatively coupled to the controller  20 , such that upon detection of a second unique property, a second signal  42  is sent to the controller  20 , instructing the controller to send an emergency stop command and/or reverse command to the hydraulic cylinder  18  operating the moveable shear blade  16 . It is also within the scope of the present invention that the controller  20  be configured to send an emergency stop command and/or reverse command to the hydraulic cylinder  18  only after the first and second unique properties have been detected within the zone  30  concurrently. It is likewise within the scope and spirit of the present invention to have an alternate second exemplary embodiment that provides a second sensor  44  in the form of a mobile sensor  44  carried on the worker&#39;s glove  34  or appendage to detect the second unique property emanating from the second device  46  and transmit a signal  48  to the controller  20  as shown in FIG. 6.  
         [0030]    Following from the above description and invention summaries, it should be apparent to those of ordinary skill in the art that, while the methods and apparatuses herein described constitute exemplary embodiments of the present invention, it is to be understood that the inventions contained herein are not limited to these precise embodiments and that changes may be made to them without departing from the scope of the inventions as defined by the claims. Additionally, it is to be understood that the invention is defined by the claims and it not intended that any limitations or elements describing the exemplary embodiments set forth herein are to be incorporated into the meanings of the claims unless such limitations or elements are explicitly listed in the claims. Likewise, it is to be understood that it is not necessary to meet any or all of the identified advantages or objects of the invention disclosed herein in order to fall within the scope of any claims, since the invention is defined by the claims and since inherent and/or unforeseen advantages of the present invention may exist even though they may not have been explicitly discussed herein.