Abstract:
A displacement sensor system for use with a tooling die having a die parting line between die sections includes a target that is attachable to one of the die sections and a laser sensor that is attachable to another of the die sections. The laser sensor is operative to transmit a laser toward the target, receive a reflected laser from the target, and produce a signal representing a distance between the die sections.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This invention relates to a displacement sensor system, and more particularly, to a laser sensor system that can be magnetically attached to a tooling die to detect displacement of the tooling die at a parting line. 
         [0002]    Molding machines, such as plastic injection molding machines, metal casting equipment, and the like utilize tooling dies to form a material into a desired shape. Typically, the tooling die includes a movable die section and a fixed die section that define a cavity in the desired shape. The molding machine exerts a clamping force that holds the die sections together at a parting line while injecting melted material into the cavity under an injection pressure. The material then cools and solidifies in the desired shape. 
         [0003]    One drawback of such molding machines and tooling dies is that variations in the molding machine may cause the injection pressure to be greater than the clamping force. This may cause the die sections to open a small amount at the parting line during injection of the melted material. For example, the die sections may open a few thousandths of an inch and allow melted material to flow from the cavity, which can result in “flash” on the molded component and damage the tooling die. 
         [0004]    One proposed solution is to monitor the separation distance between the die sections using a sensor. A potential barrier to using a sensor is sufficiently securing the sensor to the die sections to permit accurate measurement. Additionally, molding machines typically use a variety of different tooling dies over a period of time to mold different components. Therefore, there is an additional desire to be able to move the sensor from one tooling die to another tooling die. This invention addresses these needs and overcomes the shortcomings and drawbacks of the prior art. 
       SUMMARY OF THE INVENTION 
       [0005]    An example displacement sensor system for use with a tooling die having a die parting line between die sections includes a target that is attachable to one of the die sections and a laser sensor that is attachable to the other die section. The laser sensor is operative to transmit a laser toward the target, receive a reflected laser from the target, and produce a signal representing a distance between the die sections. 
         [0006]    In another aspect, a displacement sensor system includes at least one sensor member for detecting a distance between die sections, where the at least one sensor member includes at least one magnet for magnetically attaching the sensor member to one of the die sections. Thus, the magnet also provides a method of attaching the sensor member to the tooling die in a removable manner. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows. 
           [0008]      FIG. 1  illustrates an example molding machine having a displacement sensor system. 
           [0009]      FIG. 2  illustrates an example of the displacement sensor system. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0010]      FIG. 1  illustrates selected portions of an example displacement sensor system  10  used in a molding machine  12 . In this example, the molding machine  12  is a polymer injection molding machine. However, it is to be understood that this is not a limitation on the disclosed examples, and that there are various other types of molding machines that may benefit from the disclosed examples. 
         [0011]    In the illustrated example, the molding machine  12  includes an injection section  14  that receives and melts a polymer that is to be injection molded. The liquid polymer is injected under an injection pressure into a cavity  16  formed between tooling die sections  18   a  and  18   b.  In this example, the die section  18   a  is fixed relative to the die section  18   b,  which moves along direction  20  to open or close the cavity  16 . When in a closed position, the die sections  18   a  and  18   b  abut at a parting line  22 . 
         [0012]    The displacement sensor system  10  includes a first sensor member  32  attached to the die section  18   a  and a second sensor member  34  attached to the die section  18   b.  The sensor members  32  and  34  cooperate to detect a displacement distance between the die sections  18   a  and  18   b.  For example, the first sensor member  32  transmits a signal representing the displacement distance through line  36  to a controller  38 . 
         [0013]    In this example, the controller  38  includes a display  40  for providing a visual indication of the displacement distance to an operator. Optionally, the controller  38  may also include an alarm  42  in the form of the speaker that provides an audible indication in response to the displacement distance varying from a predetermined threshold, such as a predetermined acceptable range. Alternatively, the alarm may be in the form of a visual indication displayed on the display  40 . 
         [0014]    Line  44  electrically connects the controller  38  to an injection machine controller  46 . The injection machine controller  46  controls operation of the injection machine  12 , such as opening and closing of the die sections  18   a  and  18   b,  a clamp force that holds the die sections  18   a  and  18   b  together, the injection pressure, and other operating parameters of the injection machine  12 . For example, the injection machine controller  46  may increase the clamping force in response to the displacement distance varying from the predetermined threshold. The controller  38  may include hardware, software, or a combination of hardware and software for storing values of the predetermined threshold, and comparing the displacement distance to the stored values to determine whether the displacement distance varies. If the displacement distance varies, the controller  38  may signal the injection machine controller  46  to increase the clamping force. 
         [0015]    The controller  38  may also save a log the signal from the first sensor member  42  or calculated distances over a desired period of time. Logging of the signal or displacement distance values provides the benefit of having a history of displacement distances over a period of operation of the molding machine  12 . For example, the history may be over a period of time when the molding machine  12  is automatically operated without supervision of an operator. 
         [0016]      FIG. 2  illustrates an example of the displacement sensor system  10 . In this example, the first sensor member  32  and the second sensor member  34  include respective magnets  72   a  and  72   b  for attaching the sensor members  32  and  34  to the respective die sections  18   a  and  18   b.  In one example, the magnets  72   a  and  72   b  are permanent magnets. Attaching the sensor members  32  and  34  using the magnets  72   a  and  72   b  provides the benefit of removably securing the sensor members  32  and  34  to the die sections  18   a  and  18   b.  Additionally, the magnets  72   a  and  72   b  firmly affix the sensor members  32  and  34  such that the sensor displacement system  10  can accurately detect the distance between the die sections  18   a  and  18   b  without significant variation caused by movement of the die section  18   b  or vibration from the molding machine  12 . 
         [0017]    Alternatively, the first sensor member  32 , the second sensor member  34 , or both may be attached to the die sections  18   a  and  18   b  using a fastener  82  rather than the magnets  72   a  and  72   b.  The magnets  72   a  and  72   b  or the fastener  82  provide the benefit of allowing the sensor members  32  and  34  to be removed from the die sections  18   a  and  18   b  and secured to another tooling die used in the molding machine  12 , or used with another molding machine. The magnets  72   a  and  72   b  have the added benefit of not requiring any alteration to the die sections  32  and  34 , such as the machining of screw threads. Thus, the displacement sensor system  10  is portable and may be used with a variety of different tooling dies. 
         [0018]    In the disclosed examples, the first sensor member  32  is a laser sensor and a second sensor member  34  is a target. For example, the laser sensor includes a laser diode  56 , a laser image sensor  58  (e.g., a charge coupled device), and a processor  60 . The target includes a reflective surface  62 . 
         [0019]    In operation, the laser diode  56  transmits a laser  92  toward the second sensor member  34 . The laser  92  reflects off of the reflective surface  62  in the form of a reflected laser  94 . The laser image sensor  58  receives the reflected laser  94  and transmits an electrical signal along line  96  to the processor  60 . The electrical signal represents the location on the laser image sensor  58  that receives the reflected laser  94 . As the die section  18   b  moves relative to the die section  18   a,  the angle of the reflected laser  94  changes such that the received location on the laser image sensor  58  changes. Thus, the received location corresponds to the distance between the die sections  18   a  and  18   b.    
         [0020]    The processor  60  may be used to calibrate or calculate the distance between the die sections  18   a  and  18   b  based upon the signal received from the laser image sensor  58 . The processor  60  then sends an electrical signal to the controller  38  that represents the displacement distance between the die sections  18   a  and  18   b.  In one example, the laser sensor and target are capable of measuring distances as low as one mil between the die sections  18   a  and  18   b.  Given this description, one of ordinary skill having the benefit of this disclosure will be able to select a suitable laser sensitivity to meet their particular needs. 
         [0021]    Although a combination of features is shown in the illustrated examples, not all of them need to be combined to realize the benefits of various embodiments of this disclosure. In other words, a system designed according to an embodiment of this disclosure will not necessarily include all of the features shown in any one of the Figures or all of the portions schematically shown in the Figures. Moreover, selected features of one example embodiment may be combined with selected features of other example embodiments. 
         [0022]    The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this disclosure. The scope of legal protection given to this disclosure can only be determined by studying the following claims.