Abstract:
An apparatus for testing an edge of a workpiece for sharpness includes a body, a probe extending outwardly and pivotably mounted from the body, the probe is biased in a direction for placement against an edge of a workpiece with a predetermined force, a test head on a distal end of the probe for mounting test tape for physical contact with an edge as a test medium, a test point for mounting to the workpiece, and a continuity circuit mounted to the body in electrical communication with the test head and the test point for providing a predetermined electrical current between the test head and the test point through the workpiece when the test tape is cut sufficiently by the workpiece to allow the test head to touch the workpiece to form a complete circuit.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates broadly to apparatus and methods for the nondestructive testing of workpieces, equipment, and other industrial items. More particularly, the present invention relates to an apparatus for testing the sharpness of edges of workpieces comprised in household appliances and other consumer goods. 
     Various hardware and equipment such as appliances and other such consumer goods often comprise workpieces formed from metal. Such metal workpieces are configured into shapes having edges that may be considered sharp and, for example, when such workpieces with sharp edges are comprised in a household appliance, the sharp edges may snag the clothing of a person using the household appliance. Thus, it is known to use a sharp edge test apparatus to assess the degree of sharpness of sharp edges associated with household appliances or other equipment. 
     Underwriters Laboratories, which is an independent, not-for-profit product safety certification organization that tests products, has promulgated a test for testing edge sharpness in an effort to encourage a uniform standard for edge sharpness. This test for testing edge sharpness promulgated by Underwriters Laboratories is denominated Test For Sharpness Of Edges On Equipment and has been made available as UL Form 1439 (“UL 1439”) (ISBN 0-7629-0275-2). A general test apparatus specified by Underwriters Laboratories for performing a test for testing edge sharpness includes two sensing tapes layered on top of an indicating tape to provide a three-layer tape arrangement on the test head of the sharp edge test apparatus. The sharp edge test apparatus uses an arm to support the test head and the arm is spring-biased to apply a predetermined force to the edge of the appliance as it is moved therealong and, if the tape is cut, an analysis is conducted and a subjective determination made whether or not the edge has sufficiently cut the tape to render the edge dangerous and therefore fail the test. A test apparatus having a sensing tape carried on a test head is available from Excellent Technology Co. of Hong Kong and features removable test heads to speed up ongoing testing operations. 
     While a test for testing edge sharpness such as the test just described may yield useful results, tests of this type involving a visual observation by a test performer that the sensing tape has been cut disadvantageously bring with them an element of subjective interpretation—namely, a subjective interpretation by the test performer as whether a sensing tape has, in fact, been cut or has not been cut. It would therefore be desirable if a test for testing edge sharpness could be performed that diminishes, if not entirely eliminates, the necessity for a test performer to subjectively interpret the test results as to whether a sensing tape has been sufficiently cut or not cut when deployed during a test for testing edge sharpness. 
     SUMMARY OF THE INVENTION 
     In accordance with the recognition brought forth by the present invention that it would be desirable if a test for testing edge sharpness could be performed that diminishes, if not entirely eliminates, the necessity for a test performer to subjectively interpret the test results as to whether a sensing tape has been sufficiently cut or not cut when deployed during a test for testing edge sharpness, it is accordingly an object of the present invention to provide an edge test apparatus that diminishes the necessity for a test performer to subjectively interpret test results as to whether a sensing tape has been sufficiently cut or not cut when deployed during a test for testing edge sharpness. 
     It is accordingly an additional object of the present invention to provide an edge test apparatus which provides an instant response to an edge test. 
     It is another object of the present invention to provide such an edge test apparatus which provides an objective test regarding the sharpness of the edge. 
     It is a further object of the present invention to provide such an edge test apparatus that maybe readied for use in a manner more rapid than the prior edge test apparatus. 
     To those and other ends, the present invention is directed to an apparatus for testing an edge of a workpiece for sharpness including a body; a probe extending outwardly from the body and pivotably mounted thereto, the probe being biased by biasing means in a direction for placement against an edge of a workpiece with a predetermined force; a test head disposed on a distal end of the probe for mounting test tape for physical contact with an edge as a test medium; a test point for mounting to the workpiece; and a continuity circuit mounted to the body in electrical communication with the test head and the test point for providing a predetermined electrical current between the test head and the test point through the workpiece when the test tape is cut sufficiently by the workpiece to allow the test head to touch the workpiece to form a complete circuit and thereby use electrical continuity as an indication of an excess of edge sharpness. 
     Sharpness is a difficult concept to quantify. There are no units for sharpness, yet different degrees of sharpness exist, to the extent that there can be an excess, if a predetermined standard is set for acceptable sharpness. UL 1439 sets forth the criteria for determining whether an edge has become unacceptably, therefore excessively sharp. Accordingly, with such parameters set, “an excess of edge sharpness” is a definite, measurable parameter. 
     Preferably, the apparatus further includes a continuity indicator to provide an indication that electrical continuity has been achieved during a test, thereby indicating excess edge sharpness. It is preferred that the continuity circuit be configured such that a current of at least 5 mA is considered continuity for the purposes of an indication of excess edge sharpness, and more specifically, the continuity circuit is configured such that a current of 5 mA activates the indicator for the purposes of an indication of excess edge sharpness. 
     It is preferable that the apparatus further includes a continuity indicator to provide an indication that electrical continuity has been achieved during a test, thereby indicating excess edge sharpness, the indicator remaining active until reset; and a reset switch is disposed in the continuity circuit for interrupting current flow within the continuity circuit including current to the indicator and maintaining such interruption until continuity is achieved during a sharpness test, thereby preparing the continuity circuit for testing. 
     Preferably, the apparatus further includes a continuity indicator to provide an indication that electrical continuity has been achieved during a test, thereby indicating excess edge sharpness, the indicator remaining active until reset and a reset switch disposed in the continuity circuit for interrupting current flow within the continuity circuit including current to the indicator and maintaining such interruption until continuity is achieved during a sharpness test, thereby preparing the continuity circuit for testing; and a second indicator providing an indication that the continuity circuit has been reset and is ready for use in testing an edge of a workpiece for sharpness. 
     It is further preferred that the continuity circuit include a main power switch for electrically disabling the apparatus when not being used for testing an edge of a workpiece for sharpness. 
     Preferably, the probe is electrically conductive and in electrical communication with both the test head and the continuity circuit. Alternately, the test head may be wired to the continuity circuit. 
     The present invention also includes a method for testing an edge of a workpiece for sharpness using the present apparatus. The present method includes the steps of providing an apparatus for testing the edge of a workpiece for sharpness including a body; a probe extending outwardly from the body and pivotably mounted thereto, the probe being biased by biasing means in a direction for placement against an edge of a workpiece with a predetermined force; a test head disposed on a distal end of the probe for mounting test tape for physical contact with an edge as a test medium; a test point for connecting to the workpiece; and a continuity circuit mounted to the body in electrical communication with the test head and the test point for providing a predetermined electrical current between the test head and the test point through the workpiece when the test tape is cut sufficiently by the workpiece to allow the test head to touch the workpiece to form a complete circuit and thereby use electrical continuity as an indication of an excess edge sharpness. 
     The method further includes the steps of applying a plurality of tape members in a layered configuration on the test head in a predetermined manner; and connecting the test point to the workpiece. Next, the method includes the step of applying the tape members on the test head to the edge to be tested by applying a predetermined force using the body, the probe and the biasing means and drawing a stroke of predetermined length across the edge under test. 
     The next method step includes inspecting the apparatus for an indication that continuity had been achieved wherein the tape was cut by the edge under test sufficiently to make electrical contact between the test head and the workpiece, thereby allowing electrical communication between the test head and the test point via the continuity circuit and the workpiece, and thereby indicating to the user that the edge tested had excess sharpness. 
     It is preferred that the step of providing an apparatus includes providing such an apparatus with a continuity indicator to provide an indication that electrical continuity has been achieved during a test, thereby indicating excess edge sharpness and the step of inspecting the apparatus includes inspecting the indicator. 
     It is further preferred that the step of providing an apparatus includes providing a continuity indicator to provide an indication that electrical continuity has been achieved during a test, thereby indicating excess edge sharpness, the indicator remaining active until reset and a reset switch disposed in the continuity circuit for interrupting current flow to the continuity circuit including current to the indicator and maintaining such interruption until continuity is achieved during a sharpness test, thereby preparing the continuity circuit for testing; and the step of inspecting the apparatus includes inspecting the indicator and resetting the continuity circuit using the reset switch in preparation for further use. 
     Preferably, the step of providing an apparatus includes providing a continuity indicator to provide an indication that electrical continuity has been achieved during a test, thereby indicating excess edge sharpness the indicator remaining active until reset, a reset switch disposed in the continuity circuit for interrupting current flow to the to the continuity circuit including current to the indicator and maintaining such interruption until continuity is achieved during a sharpness test, thereby preparing the continuity circuit for testing; and a second indicator providing an indication that the continuity circuit has been reset and is ready for use in testing an edge of a workpiece for sharpness. It is also preferred that the step of inspecting the apparatus includes inspecting the indicator and resetting the continuity circuit using the reset switch in preparation for further use. The method further preferably comprises the step of inspecting the second indicator for an indication that the continuity circuit has been reset and is ready for use in testing an edge of a workpiece for sharpness. 
     Preferably the step of providing an apparatus includes providing such an apparatus with an electrically conductive probe in electrical communication with both the continuity circuit and the test head. Alternately, the step of providing an apparatus includes providing such an apparatus with a test head wired to the continuity circuit. 
     The present invention can also be defines in terms of a carrier, a trip component and a signal generating element. In that manner, the present invention is directed to an apparatus for testing an edge of a workpiece for sharpness, the apparatus including a carrier and a trip component mounted on the carrier. The trip component is deployable against an edge of a workpiece and is also disposable between a trip condition that occurs when the trip component is deployed against an edge of a workpiece, the edge of the workpiece has a predetermined sharpness characteristic, and the predetermined sharpness characteristic of the edge of the workpiece effects a change in the trip component and a non-trip condition that occurs when the trip component is not deployed for testing against an edge of a workpiece and the edge of the workpiece has a predetermined sharpness characteristic. 
     The present invention also includes a signal generating element, the signal generating element being operatively connected to the trip component. The signal generating element provides an electrical current that, when the trip component is in its trip condition, flows through the signal generating component and the trip component in a complete electrical circuit and the signal generating element operates to generate a signal in response to the flow of electrical current therethrough in a complete electrical circuit. 
     Preferably, the trap component is in electrical communication with the signal generating element and the signal generating element is in electrical communication with an edge under test such that a complete circuit is formed through the trip component, the signal generating element and the edge under test when the trip component is in its trip condition. It is further preferred that the trip component includes an electrically conductive test head for supporting test tape for physical contact with an edge as a test medium. 
     The present invention may also include an indicator light operative responsive to a signal generated by the signal generating element. The present invention may also include a reset switch in electrical communication with the indicator light, signal generating element and the trip component operable to effect a change in the trip component from a trip condition to a non-trip condition after the trip component has been used for testing against an edge of a workpiece, and to effect a change in the signal generating element from a signal generating condition to a non-signal generating condition after the signal generating element has been used during an edge sharpness test. 
     By the above, the present invention provides a simple, objective sharp edge test apparatus that complies with standards set forth in UL 1439. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagrammatic view of an apparatus for testing an edge for sharpness according to the preferred embodiment of the present invention; 
         FIG. 2  is a diagrammatic view of the edge test apparatus illustrated in  FIG. 1  showing internal components; 
         FIG. 3  is a partial end view of the test head of the edge test apparatus illustrated in  FIG. 1 ; 
         FIG. 4  is a flow chart of the method according the preferred embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Turning now to the drawings and more particularly to the  FIGS. 1 and 2 , an apparatus for testing the sharpness of an edge of a workpiece is illustrated generally at  10  and includes a carrier such as a housing or body  12 . The body  12  may be a clam-shell type housing and it may be molded from plastic, formed from metal or any other structural material that will support the inner workings of the test apparatus  10  as seen in FIG.  2 . 
     Underwriters Laboratories, which is an independent, not-for-profit product safety certification organization that tests products, has promulgated a test for testing edge sharpness in an effort to encourage a uniform standard for edge sharpness. This test for testing edge sharpness promulgated by Underwriters Laboratories is denominated Test For Sharpness Of Edges On Equipment and has been made available as UL Form 1439 (“UL 1439) (ISBN 0-7629-0275-2). UL 1439 is referenced herein as a source of further information concerning one test for testing edge sharpness that the apparatus for testing the sharpness of an edge of a workpiece and the method of the present invention can perform. However, it should be noted that the apparatus for testing the sharpness of an edge of a workpiece and the method of the present invention can perform other tests for testing edge sharpness and the suitability of the apparatus for testing the sharpness of an edge of a workpiece and the method of the present invention for performing tests for testing edge sharpness is in no way restricted to only those tests for testing edge sharpness performed in accordance with the test promulgated by Underwriters Laboratories denominated Test For Sharpness Of Edges On Equipment and available as UL Form 1439 (“UL 1439”) (ISBN 0-7629-0275-2). 
     A probe  14  is rotatably mounted to a probe support  26  which is in turn mounted to the body  12 . A biasing arrangement, in this case a spring  18  is wound around a hub  24  which is rotatably mounted to the probe support  26 . The probe  14  extends outwardly from the body  12  from its mounted position at the hub  24 , such that the probe  14  transmits the biasing influence of the spring  18  to its distal end, for ultimate edge engagement, with a constant downwardly directed force F 1  of 1.5 pounds (6.7 N). 
     The present invention also includes a trip component including a test head  16  provided at the end of the probe  14 . The test head  16  is electrically conductive, and the entire probe  14  may be electrically conductive as well. As seen in  FIG. 3 , an inner layer of sensing tape  22  is provided around approximately one half the outer diameter of the surface of the test head  16 . The inner layer is sensing tape number  2 , a white vinyl foam tape described in UL 1439 Section 5.1(c). Attached to the inner layer is an outer layer of sensing tape  20 , namely, sensing tape number  1 , a tetrafluorethylene tape as described in UL 1439 Section 5.1(d). 
     Returning now to  FIG. 1 , a continuity circuit  30  which forms all or part of a signal generating element is provided to conduct the sharpness test by determining whether electrical continuity exists between the test head  16  and a test point  36 , which may be formed as an alligator clip in electrical communication with the continuity circuit for clipping to the workpiece, via the workpiece W and associated wiring  32 ,  34 . If the tape  20  is sufficiently cut so as to expose the conductive tape head  16  to the edge E of the workpiece W, continuity is achieved and the edge E fails the test. The circuit  30  is shown in  FIG. 1  away from the body  12  of the tester  10  for clarity, with wiring  32 ,  34  shown for completeness of the circuit path, but it will be understood by those skilled in the art that the circuit  30  may be mounted to the body, for example within the clam-shell structure thereof. 
     It is also well within the skill of one in the ordinary skill of the art to construct a DC continuity circuit of the type described and applied herein with the features described herein. Accordingly, a detailed description of the actual circuit is not warranted here. An on/off switch  38  is provided for main power control. An indicator light  40  is provided to become illuminated when continuity is achieved thereby causing the edge E of the workpiece W to fail the test. Optionally, an audible indicator may be used in place of, or in conjunction with the indicator light  40 . A reset switch  42  is provided to reset the continuity circuit in preparation for the next test. In order to inform the user that the tester  10  is ready for the next test, a ready light  44  is provided in the circuit  30 . Optionally, an indicator may be used to inform the user that the apparatus is in a proper position for executing the test on an edge of a workpiece. It will be understood by those skilled in the electronic arts that the indicators and switches may be positioned on the outside of the test apparatus  10  for convenient access by a user and need not be mounted directly to the circuit  30  as illustrated generally in FIG.  1 . 
     In order to complete the circuit illustrated in  FIG. 1 , a main wire  32  extends from the conductive head  16  and, as seen in  FIG. 1 , through the probe  14  to the circuit  30 . In addition, a second conductor  34  is provided between a clip  36  and the circuit  30  with the additional clip  36  being mounted to the workpiece W as a test point so that continuity can be established. As seen in  FIG. 2 , the wire  32  is wrapped around the probe  14  to ultimately reach the conductive test head  16 . Optionally, as seen in  FIG. 1 , the probe  14  may be electrically conductive itself and in electrical communication with the test head such that the wire around the probe  14  may be omitted. Either technique would provide a workable test apparatus  10 . 
     Turning now to  FIG. 4 , in conformance with UL 1439 and a preferred embodiment of present invention, the method of the present invention is illustrated generally at  50  in the manner of a flow chart. Initially, the power is turned on to the test apparatus  10  as illustrated at  52 . The operator then checks for a system ready light  44  at box  54  and if no light is indicated as seen in box  56 , the user presses the reset as seen at box  60  and proceeds with the test. If the system ready light  54  is illuminated, as indicated at box  58 , the user proceeds with the test. The test point clip  36  is attached to some portion of the workpiece W so that if continuity is established, current can flow. 
     Next, the user applies the test apparatus  10  to the edge E under test as seen in  FIG. 1 , thereby applying constant 1.5 pounds of force. A test apparatus  10  is then immediately moved along the edge E a distance of approximately 2 inches (50.8 millimeters) and then back to its starting position without removal of the test apparatus  10  from the edge E. It is then withdrawn from the edge E. The total distance of engagement between the edge E and the tape covered test head  16  is not to exceed 4 inches (101 mm). The time of travel is to be between two seconds and 5 seconds. That is the test applied at box  64  in FIG.  4  and as discussed in UL 1439 at paragraph 7.4. 
     Once the test has been performed, the user queries whether current from the test head  16  to test clip  36  exceeded 5 mA, In order to make this assessment, the first indicator light  40  is viewed to determine whether the Edge E has passed or failed the test. If the Edge E has failed the test, in that current from the test head  16  to test clip  36  exceeds 5 mA, as illustrated at  68 , the fail indicator  40  illuminates as indicated at  70 . If the current is not present and the fail indicator  40  does not illuminate, as illustrated at  72  the edge E has passed the test as illustrated at  74  in FIG.  4 . 
     By the above, the present apparatus and method can be used to determine whether an edge of an industrial workpiece such as an appliance is in compliance with UL standards in an objective and rapid manner. The use of a go/no-go type operational test provides such objectivity and can enhance the consistency of the test results as well as reducing the time necessary to apply the test. 
     It will therefore be readily understood by those persons skilled in the art that the present invention is susceptible of a broad utility and application. While the present invention is described in all currently foreseeable embodiments, there may be other, unforeseeable embodiments and adaptations of the present invention, as well as variations, modifications and equivalent arrangements, that do not depart from the substance or scope of the present invention. The foregoing disclosure is not intended or to be construed to limit the present invention or otherwise to exclude such other embodiments, adaptations, variations, modifications and equivalent arrangements, the present invention being limited only by the claims appended hereto and the equivalents thereof.