Abstract:
A coating adhesive strength and shear strength measuring apparatus is provided which can measure both the adhesive strength and the shear strength of the coating of a test piece at higher accuracy while its structure being simple and inexpensive.  
     A vertical pressure sensor  15  is linked at one end to a guide shaft  14  which is movable in two, vertical and parallel, direction relative to the coating surface of a test piece S while a parallel pressure sensor  17  is linked at its first end by a link  16  to the other end of the vertical pressure sensor  15.  The second end of the parallel pressure sensor  17  is linked to a cutting knife  18.  As the coating of the test piece S is sliced with the cutting knife  18,  the vertical pressure and the parallel pressure exerted on the cutting knife  18  can be measured.  
     Since no sliding guide shaft is provided between the cutting knife and each of the pressure sensors, the sliding related interruption is hardly involved and the measurement can be improved in the accuracy. Also, the cutting depth and the cutting plane can be affected by no sliding guide shaft play. The absence of any sliding guide shaft can contribute to the simple and inexpensive arrangement of the apparatus.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a coating adhesive strength and shear strength measuring apparatus and more particularly to a coating adhesive strength and shear strength measuring apparatus which can accurately measure the adhesive strength and the shear strength of a coating film bonded to a test piece while its structure is simple and low in the cost.  
           [0003]    2. Description of the Related Art  
           [0004]    Disclosed in Japanese Patent Laid-open Publication (Heisei)3-67151 is a conventional coating adhesive strength and shear strength measuring apparatus which comprises a cutting knife holder arranged for moving in two, vertical and parallel, directions relative to a vertical sliding guide shaft which can be moved in vertical to the coating surface of a test piece and a parallel sliding guide shaft which can be moved in parallel to the coating surface, a cutting knife mounted to the cutting guide shaft for slicing the coating, a vertical pressure sensor for measuring a repulsion in the vertical direction along the vertical sliding guide shaft, and a parallel pressure sensor for measuring a resistance to the cutting action in the parallel direction along the parallel sliding guide shaft.  
           [0005]    The conventional coating adhesive strength and shear strength measuring apparatus is designed for measuring the repulsion in the vertical direction from a displacement of the vertical sliding guide shaft and the resistance to the cutting action in the parallel direction from a displacement of the parallel sliding guide shaft. Accordingly, a measurement of the repulsion includes a sliding related resistance derived from the displacement of the vertical sliding guide shaft while a measurement of the resistance to the cutting action includes a sliding related resistance derived from the displacement of the parallel sliding guide shaft.  
           [0006]    It is however disadvantageous that the measurements of the repulsion and the resistance to the cutting action are substantially incorrect as they include the sliding related resistance on the sliding guide shafts.  
           [0007]    Also, since there is a play gap (clearance) between the vertical sliding guide shaft and its supporting members, the depth of the cutting may be incorrect. Equally, as a play gap (clearance) is provided between the parallel sliding guide shaft and its supporting members, the cutting plane may hardly be smooth. Accordingly, the cutting plane will be elongated with much difficulty.  
           [0008]    Moreover, the arrangement including both the vertical sliding guide shaft and the parallel sliding guide shaft becomes intricate and its overall cost win be increased.  
           [0009]    It is hence an object of the present invention to provide a coating adhesive strength and shear strength measuring apparatus which can accurately measure the adhesive strength and the shear strength of the coating of a test piece while being simple in the structure and inexpensive in the cost.  
         SUMMARY OF THE INVENTION  
         [0010]    As a first feature of the present invention, a coating adhesive strength and shear strength measuring apparatus for cutting the coating of a test piece with a cutting knife, measuring the force vertical to the coating and the force parallel to the coating which both are exerted on the cutting knife, and calculating the adhesive strength and the shear strength of the coating is provided comprising: a stage means arranged movable in two, vertical and parallel, directions relative to the coating; a vertical pressure sensor linked at one end to the stage means; a parallel pressure sensor linked at its first end to the other end of the vertical pressure sensor; and the cutting knife linked to the second end of the parallel pressure sensor, wherein the vertical force exerted on the cutting knife is measured by the vertical pressure sensor and the parallel force exerted on the cutting knife is measured by the parallel pressure sensor.  
           [0011]    In action, the stage means may be moved while the test piece remains stationary. Alternatively, the test piece may be moved while the stage means remains stationary or both may be moved.  
           [0012]    The coating adhesive strength and shear strength measuring apparatus of the first feature has the cutting knife mounted to the parallel pressure sensor with no sliding guide shaft disposed between the cutting knife and the parallel pressure sensor. This allows the parallel pressure to suffer from no sliding related resistance and its measurement to be accurate. Also, the cutting knife is linked by the parallel pressure sensor to the vertical pressure sensor with no sliding guide shaft disposed between the cutting knife and the vertical pressure sensor. This allows the vertical pressure to suffer from no sliding related resistance and its measurement to be accurate. Moreover, the cutting depth and the cutting plane can be affected by no sliding guide shaft play. Accordingly, both the adhesive strength and the shear strength of the coating of a test piece can be measured at higher accuracy. As no sliding guide shaft is involved, the structure of the apparatus will be simple and inexpensive.  
           [0013]    As a second feature of the present invention, a coating adhesive strength and shear strength measuring apparatus for cutting the coating of a test piece with a cutting knife, measuring the force vertical to the coating and the force parallel to the coating which both are exerted on the cutting knife, and calculating the adhesive strength and the shear strength of the coating is provided comprising: a stage means arranged movable in two, vertical and parallel, directions relative to the coating; a parallel pressure sensor linked at one end to the stage means; a vertical pressure sensor linked at its first end to the other end of the parallel pressure sensor; and the cutting knife linked to the second end of the vertical pressure sensor, wherein the vertical force exerted on the cutting knife is measured by the vertical pressure sensor and the parallel force exerted on the cutting knife is measured by the parallel pressure sensor.  
           [0014]    In action, the stage means may be moved while the test piece remains stationary. Alternatively, the test piece may be moved while the stage means remains stationary or both may be moved.  
           [0015]    The coating adhesive strength and shear strength measuring apparatus of the second feature has the cutting knife mounted to the vertical pressure sensor with no sliding guide shaft disposed between the cutting knife and the vertical pressure sensor. This allows the vertical pressure to suffer from no sliding related resistance and thus its measurement to be accurate. Also, the cutting knife is linked by the vertical pressure sensor to the parallel pressure sensor with no sliding guide shaft disposed between the cutting knife and the parallel pressure sensor. This allows the parallel pressure to suffer from no sliding related resistance and thus its measurement to be accurate. Moreover, the cutting depth and the cutting plane can be affected by no sliding guide shaft play. Accordingly, both the adhesive strength and the shear strength of the coating of a test piece can be measured at higher accuracy. As no sliding guide shaft is involved, the structure of the apparatus will be simple and inexpensive.  
           [0016]    As a third feature of the present invention, the coating adhesive strength and shear strength measuring apparatus is modified wherein the stage means is slightly moved up to 500 μm by the action of piezoelectric devices.  
           [0017]    The stage means may be implemented by an XY stage driven by a stepping motor or an ultrasonic oscillating motor. As the XY stage has sliding portions, its clearance should allow a margin of 1 μm. The clearance may however produce an error in the measurement.  
           [0018]    The coating adhesive strength and shear strength measuring apparatus of the third feature has the movable stage driven by piezoelectric devices and its overall components including the support base and the cutting knife can thus assembled integrally with no involvement of clearance. Accordingly, the measurement can be improved in the accuracy.  
           [0019]    As a fourth feature of the present invention, the coating adhesive strength and shear strength measuring apparatus further comprises a graphic means for converting changes in the vertical pressure measured by the vertical pressure sensor, the parallel pressure measured by the parallel pressure sensor, and the depth of cutting by the cutting knife into graphic representations.  
           [0020]    The coating adhesive strength and shear strength measuring apparatus of the fourth feature allows changes in the vertical pressure, the parallel pressure, and the cutting depth measured to be converted into graphic representations which can explicitly exhibit the relationship between the changes. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]    [0021]FIG. 1 is a front explanatory view of the structure of a coating adhesive strength and shear strength measuring apparatus according to a first embodiment of the present invention;  
         [0022]    [0022]FIG. 2 is a primary explanatory view illustrating a cutting action on the coating of the coating adhesive strength and shear strength measuring apparatus of the embodiment of the present invention; and  
         [0023]    [0023]FIG. 3 is a front explanatory view of the structure of a coating adhesive strength and shear strength measuring apparatus according to a second embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0024]    Some embodiments of the present invention will be described referring to the relevant drawings. It would be understood that the present invention is not limited to the embodiments.  
         [0025]    (First Embodiment)  
         [0026]    [0026]FIG. 1 is a front explanatory view of a coating adhesive strength and shear strength measuring apparatus showing the first embodiment.  
         [0027]    The coating adhesive strength and shear strength measuring apparatus denoted at  100  has a guide shaft  2  fixedly mounted on a support bed  1 . A sliding member  3  is movably mounted on the guide shaft  2 .  
         [0028]    A nut unit  7  has a threaded rod  6  screwed therein and is fixedly mounted to the sliding member  3 .  
         [0029]    The threaded rod  6  is joined at the other end to a parallel motion motor  5 . As the parallel motion motor  5  rotates, the threaded rod  6  is spun to actuate the sliding movement in a horizontal direction of the nut unit  7 .  
         [0030]    The parallel motion motor  5  is a stepping motor fixedly mounted to a stationary block  4 .  
         [0031]    A pivotal head  8  is joined to the nut unit  7  and arranged for pivotal movement on the vertical plane with the use of a knob  30 .  
         [0032]    The pivotal head  8  may be replaced by a tiltable test piece head.  
         [0033]    A guide shaft  9  has a sliding member  10  movably mounted thereon and is fixedly mounted to the pivotal head  8 .  
         [0034]    A nut unit  14  has a threaded rod  13  threaded therein and is fixedly mounted to the sliding member  10 .  
         [0035]    The threaded rod  13  is joined at the other end to a vertical motion motor  12 . As the vertical motion motor  12  rotates, the threaded rod  13  is spun to actuate the sliding movement in a vertical direction of the nut unit  14 .  
         [0036]    The vertical motion motor  12  is a stepping motor fixedly mounted by a link  11  to a stationary block  8 .  
         [0037]    A vertical pressure sensor  15  is fixedly mounted at one end to the nut unit  14 .  
         [0038]    The vertical pressure sensor  15  is a weighing load cell (e.g. the trade name “CB17” of MINEBEA Co.,Ltd) for measuring the pressure exerted in a vertical direction on the other end thereof.  
         [0039]    The first end of a parallel pressure sensor  17  is fixedly mounted by a link  16  to the other end of the vertical pressure sensor  15 .  
         [0040]    The parallel pressure sensor  17  is a weighing load cell (e.g. CB17 of MINEBEA CO.,LTD) for measuring the pressure exerted in a horizontal direction on the second end thereof.  
         [0041]    A cutting knife  18  is fixedly mounted to the second end of the parallel pressure sensor  17 .  
         [0042]    In addition, a vertical displacement sensor  19  is fixedly mounted by a support  20  to a cutting knife holder end of the parallel pressure sensor  17 .  
         [0043]    A test piece S is a coated strip which is held with its coating surface extending horizontally between a test piece bed  23  and a clamp  22 .  
         [0044]    The parallel motion motor  5  and the vertical motion motor  12  are electrically connected by an output interface  28   a  to a personal computer  28 .  
         [0045]    The vertical pressure sensor  15 , the parallel pressure sensor  17 , and the vertical displacement sensor  19  are connected by an input interface  28   b  to the personal computer  28 .  
         [0046]    Upon receiving a command from the operator, the personal computer  28  actuates both the parallel motion motor  5  and the vertical motion motor  12  to cut the coating of the test piece S. The personal computer  28  then receives a measurement of the vertical pressure from the vertical pressure sensor  15 , a measurement of the parallel pressure from the parallel pressure sensor  17 , and a depth of the cutting from the vertical displacement sensor  19 . The vertical pressure, the parallel pressure, and the depth of the cutting are then converted into graphic representations which are displayed on a display or printed down by a printer.  
         [0047]    The measurement of the coating adhesive strength and shear strength is conducted by the following steps.  
         [0048]    (1) A test piece S is placed on the test piece bed  23  by the clamp  22  with its coating surface extending horizontally. The edge of the cutting knife  18  is set in parallel to the coating surface of the test piece S. In case of using a tiltable test piece head, the coating surface of the test piece S is set in parallel to the edge of the cutting knife  18 .  
         [0049]    (2) The cutting knife  18  is lifted down by the action of the vertical motion motor  12  until it exerts a predetermined load (e.g. 1 g) against the coating surface of the test piece S. It is then determined that the depth of the cutting read from the vertical displacement sensor  19  is zero at the time.  
         [0050]    (3) The cutting knife  18  is needed in both, horizontal and vertical, directions by the action of the parallel motion motor  5  and the vertical motion motor  12  so that its edge cuts into the coating of the test piece S as shown in FIG. 2. In case that the two pressure sensors  15  and  17  are forced and deformed by any pressure during the cutting operation, the cutting plane is constantly kept parallel due to maintain the shape of parallelogram thus holding the cutting knife  18  at a desired cutting angle to the test piece S.  
         [0051]    (4) The vertical pressure (a repulsion) is measured from the output of the vertical pressure sensor  15 , the parallel pressure (a resistance to the cutting action) is measure from the output the parallel pressure sensor  17 , and the depth of the cutting is measured from the output of the vertical displacement sensor  19 . The measurements of the changes in the vertical pressure, parallel pressure, and depth of the cutting are then examined.  
         [0052]    Although the vertical pressure possibly affects the measurement of the parallel pressure of the parallel pressure sensor  17 , it is much smaller than the parallel pressure in common practice and may be negligible. Also, the parallel pressure may affect the measurement of the vertical pressure of the vertical pressure sensor  15 . This can be avoided by calculating the affection of the parallel pressure over the measurement in advance and eliminating it with its offset value. Alternatively, any affection can be ignored when the measurement is examined in its relative value but not absolute value.  
         [0053]    The coating adhesive strength and shear strength measuring apparatus  100  of this embodiment provides the following advantages.  
         [0054]    (1) As no sliding guide shaft is provided between the cutting knife  18  and the parallel pressure sensor  17 , the apparatus is free from any sliding resistance and can thus measure the parallel pressure at higher accuracy. Similarly, as no sliding guide shaft is provided between the cutting knife  18  and the vertical pressure sensor  15 , the apparatus is free from any sliding resistance and can thus measure the vertical pressure at higher accuracy.  
         [0055]    (2) The cutting depth and the cutting plane can be affected by no sliding guide shaft play.  
         [0056]    (3) As no sliding guide shaft is provided, the overall structure of the apparatus can be simple and inexpensive.  
         [0057]    The cutting knife  18  may be mounted to the second end of the vertical pressure sensor  15  which is joined at the first end by a link  16  to one end of the parallel pressure sensor  17  which is fixedly mounted at the other end to the nut unit  14 .  
         [0058]    (Second Embodiment)  
         [0059]    [0059]FIG. 3 is a front explanatory view of a coating adhesive strength and shear strength measuring apparatus according to a second embodiment of the present invention.  
         [0060]    The coating adhesive strength and shear strength measuring apparatus denoted at  200  has a piezoelectric device driving slightly movable stage  30   h  fixedly mounted on a support base  1  thereof.  
         [0061]    The piezoelectric device driving slightly movable stage  30   h  includes a stage  36   h  which is driven by a piezoelectric device to move in one direction relative to a frame  35   h  (e.g. the trade name “Nano-stage” of NANOCONROL Co.,Ltd).  
         [0062]    The piezoelectric device driving slightly movable stage  30   h  is fixedly mounted at its frame  35   h  to the support base  1  so that its relative movement is carried out in a horizontal direction. This allows the stage  36   h  to move horizontally over the support base  1 . The horizontal movement of the stage  36   h  may be within 300 μm.  
         [0063]    A link rod  32  is fixedly mounted at the lower end to the stage  36   h  of the piezoelectric device driving slightly movable stage  30   h.    
         [0064]    The other end of the link rod  32  is joined to another piezoelectric device driving slightly movable stage  30   v.    
         [0065]    The piezoelectric device driving slightly movable stage  30   v  includes a stage  36   v  which is driven by a piezoelectric device to move in one direction relative to a frame  35   v  (e.g. the trade name “Nano-stage” of NANOCONROL Co.,Ltd ).  
         [0066]    The piezoelectric device driving slightly movable stage  30   v  is fixedly mounted at its stage  36   v  to the link rod  32  so that its relative movement is carried out in a vertical direction. This allows the frame  35   v  to move vertically over the support base  1 . The vertical movement of the frame  35   v  may be within 100 μm.  
         [0067]    A vertical pressure sensor  15  is fixedly mounted at one end to the frame  35   v  of the piezoelectric device driving slightly movable stage  30   v.    
         [0068]    The vertical pressure sensor  15  is a weighing load cell (e.g. CB17 of MINEBEA CO.,LTD) for measuring the pressure exerted in a vertical direction on the other end thereof.  
         [0069]    The first end of a parallel pressure sensor  17  is fixedly mounted by a link  16  to the other end of the vertical pressure sensor  15 .  
         [0070]    The parallel pressure sensor  17  is a weighing load cell (e.g. CB17 of MINEBEA CO.,LTD) for measuring the pressure exerted in a horizontal direction on the second end thereof.  
         [0071]    A cutting knife  18  is fixedly mounted to the second end of the parallel pressure sensor  17 .  
         [0072]    In addition, a vertical displacement sensor  19  is fixedly mounted by a support  20  to a cutting knife holder end of the parallel pressure sensor  17 .  
         [0073]    A test piece S is a coated strip which is held with its coating surface extending horizontally between a test piece bed  23  and a clamp  22 .  
         [0074]    The two piezoelectric device driving slightly movable stage  30   h  and  30   v  are connected by an output interface  38   a  (e.g. the trade name “Nano-servo controller” of NANOCONROL Co.,Ltd) to a personal computer  28 .  
         [0075]    The vertical pressure sensor  15 , the parallel pressure sensor  17 , and the vertical displacement sensor  19  are connected by an input interface  28   b  to the personal computer  28 .  
         [0076]    Upon receiving a command from the operator, the personal computer  28  actuates the two piezoelectric device driving slightly movable stages  30   h  and  30   v  to cut the coating of the test piece S. The personal computer  28  then receives a measurement of the vertical pressure from the vertical pressure sensor  15 , a measurement of the parallel pressure from the parallel pressure sensor  17 , and a depth of the cutting from the vertical displacement sensor  19 . The vertical pressure, the parallel pressure, and the depth of the cutting are then converted into graphic representations which are displayed on a display or printed down by a printer.  
         [0077]    The measurement of the coating adhesive strength and shear strength is conducted by the following steps.  
         [0078]    (1) A test piece S is placed on the test piece bed  23  by the clamp  22  with its coating surface extending horizontally. The edge of the cutting knife  18  is set in parallel to the coating surface of the test piece S. In case of using a tiltable test piece head, the coating surface of the test piece S is set in parallel to the edge of the cutting knife  18 .  
         [0079]    (2) The cutting knife  18  is lifted down by the action of the piezoelectric device driving slightly movable stage  30   v  until it exerts a predetermined load (e.g. 1 g) against the coating surface of the test piece S. It is then determined that the depth of the cutting read from the vertical displacement sensor  19  is zero at the time.  
         [0080]    (3) The cutting knife  18  is moved in both, horizontal and vertical, directions by the action of the two piezoelectric device driving slightly movable stages  30   h  and  30   v  so that its edge cuts into the coating of the test piece S as shown in FIG. 2. In case that the two pressure sensors  15  and  17  are forced and deformed by any pressure during the cutting operation, the cutting plane is constantly kept parallel by due to maintain the shape of parallelogram thus holding the cutting knife  18  at a desired cutting angle to the test piece S.  
         [0081]    (4) The vertical pressure (a repulsion) is measured from the output of the vertical pressure sensor  15 , the parallel pressure (a resistance to the cutting action) is measured from the output the parallel pressure sensor  17 , and the depth of the cutting is measured from the output of the vertical displacement sensor  19 . Th measurements of the changes in the vertical pressure, parallel pressure, and depth of the cutting are then examined.  
         [0082]    The coating adhesive strength and shear strength measuring apparatus  200  of this embodiment employs the two piezoelectric device driving slightly movable stages  30   h  and  30   v  thus allowing its primary components from the support base  1  to the cutting knife  18  to be integrally assembled with no clearance as one unit hereby the measurement can highly be accurate.  
         [0083]    (Other Embodiments)  
         [0084]    (1) The cutting knife  18  may be replaced by a needle probe type sensor. This permits examination of the resistance to physical injury of the coating.  
         [0085]    (2) The cutting knife  18  may be replaced by a flat tip probe type sensor. This permits examination of the frictional property such as friction coefficient.  
         [0086]    As set forth above, each coating adhesive strength and shear strength measuring apparatus according to the present invention can measure both the adhesive strength and the shear strength of a coating at higher accuracy. Also, its structure can be built with ease and at less cost. Moreover, its overall weight can be minimized thus contributing to the portable design of the apparatus.