Abstract:
An apparatus for performing an impact test of an object of test by use of a hammer is disclosed. The apparatus includes a pendulum arm swingable in an up-down direction in response to rotation of a rotary cam. The rotary cam is driven to rotate by a rotational drive unit, so that the hammer provided on a distal end portion of the pendulum arm successively applies impacts to the object of test.

Description:
FIELD OF THE INVENTION 
   The present invention relates to an improvement of impact or resistance test apparatus. 
   BACKGROUND OF THE INVENTION 
   To prevent an illegal act called “theft from a car”, it is required for cars or automotive vehicles to have a sufficient durability against a destructive act from outside the vehicles. Generally, in automotive vehicles, front and rear window glasses and door glasses are fitted in a steel-made vehicle body, and these glasses are much more fragile than steel plates. Thus, such glasses are reinforced by heat treatment and/or by thickness increase. It is necessary to quantitatively confirm whether such reinforcing measures meet various criteria (anti-crime or crime-prevention criteria), and various impact (resistance) test apparatus have so far been used for such purposes. 
   One example of the impact test apparatus of the aforementioned type is known from Japanese Patent Application Laid-Open Publication No. 56-43526 (JP 56-43526 A) which discloses a dent test apparatus. The disclosed dent test apparatus will be discussed below with reference to  FIGS. 11A and 11B  hereof. 
   As shown in  FIG. 11A , the disclosed dent test apparatus  101  includes: a support post  103  fixedly mounted on a support table  102 ; an arm  104  vertically swingably mounted on a shaft  109  that is in turn provided on the support post  103 ; a hammer  105  fixed on a distal end surface portion of the vertically swingable arm  104 ; a handle  106  provided on another distal end surface portion of the arm  104 ; and a locking device  107  for locking the arm  104  at a swinging-movement start position. 
   First, a human test operator holds the handle  106  to cause the arm  104  to be locked with the locking device  107 . Then, the human test operator sets an object of test  108  on the support table  102  and then operates the locking device  107  to disengage the arm  104  from the locking device  107 . As shown in  FIG. 11B , the thus-disengaged arm  104  pivots about the shaft  109  downwardly or counterclockwise, so that the hammer  105  hits the object of test  108 . 
   In the aforementioned manner, the conventionally-known dent test apparatus can readily and accurately reproduce an intensity and direction of energy applied at the time of an impact. 
   In a case where the object of test is a glass of an automotive vehicle, it is recommendable that the dent test be carried out by the glass being successively hit a plurality of times, e.g. five times. Thus, in this case, the human test operator has to repeat lifting and dropping the arm  104  a plurality of times, which would undesirably increase a load on the test operator and necessary test time and thus lead to a lowered test efficiency. 
   SUMMARY OF THE INVENTION 
   In view of the foregoing prior art problems, it is an object of the present invention to provide an improved impact test apparatus capable of successively hitting an object of test. 
   According to an aspect of the present invention, there is provided an improved impact test apparatus, which comprises: a support post disposed on a base plate; a rotational drive unit supported by the support post; a rotary cam adapted to be rotated by the rotational drive unit; a pendulum arm supported by the support post for swinging movement in a vertical direction; and a hammer disposed on a distal end portion of the pendulum arm. The pendulum arm has a proximal end portion abutting against the rotary cam, and the rotary cam is rotated by the rotational drive unit in one direction and a necessary number of times. The pendulum arm is driven to rotate by the rotational drive unit via the rotary cam, so that the hammer, provided on the distal end portion of the pendulum arm, can successively applies impacts to the object of test, as a result of which the impact test efficiency can be enhanced. 
   Preferably, the impact test apparatus of the present invention further comprises a number-of-hitting detection section for detecting the number of rotation of the rotary cam to thereby detect the number of times of hitting, by the hammer, of the object of test. With the number-of-hitting detection section, it is possible to deactivate the impact test apparatus upon completion of any desired number of times of hitting, by the hammer, of the object of test. 
   Preferably, the number-of-hitting detection section includes a plurality of projections provided on one side surface of the rotary cam, a projection detecting sensor for detecting the projections, and a number-of-rotation calculation section for calculating the number of rotation of the rotary cam on the basis of detection information acquired by the projection detecting sensor. With the detecting sensor for detecting the projections on the one side surface of the rotary cam, the impact test apparatus can be readily deactivated upon completion of any desired number of times of hitting, by the hammer, of the object of test. 
   Preferably, the rotational drive unit includes a brake. With the brake, the rotation of the rotary cam can be stopped promptly upon termination of a predetermined number of impacts, and particularly; the impact tests can be performed with no trouble even if the rotary cam is rotated at a high speed. 
   Preferably, the rotary cam comprises a plurality of rotary cam members differing from each other in cam shape, the rotary cam members are mounted on a common shaft in parallel to each other, and the common shaft is moved compulsorily so that one of the plurality of rotary cam members is caused to abut against the proximal end portion of the pendulum arm. Particularly, by compulsorily moving the common shaft, the same impact test apparatus can appropriately perform impact tests on a plurality of objects of test having different heights. 
   Preferably, the rotary cam comprises a plurality of rotary cam members differing from each other in cam shape, a relay member is provided between the rotary cam members and the proximal end portion of the pendulum arm, and the relay member is moved compulsorily so that one of the plurality of rotary cam members is caused to abut against the proximal end portion of the pendulum arm. By compulsorily moving the relay member, any one of the plurality of rotary cam members can be relayed to the proximal end portion of the pendulum arm; thus, the same impact test apparatus can appropriately perform impact tests on a plurality of objects of test having different heights. 
   The following will describe embodiments of the present invention, but it should be appreciated that the present invention is not limited to the described embodiments and various modifications of the invention are possible without departing from the basic principles. The scope of the present invention is therefore to be determined solely by the appended claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Certain preferred embodiments of the present invention will be described in detail below, by way of example only, with reference to the accompanying drawings, in which: 
       FIG. 1  is a side view showing an impact test apparatus according to a first embodiment of the present invention; 
       FIG. 2  is an enlarged sectional view taken along line  2 - 2  of  FIG. 1 ; 
       FIGS. 3A-3C  are views showing the first embodiment in a test start state, hitting end state and start-position returning state; 
       FIG. 4  is a diagram showing a construction of a number-of-hitting detection section employed in the first embodiment; 
       FIG. 5  is a partly-sectional side view showing an impact test apparatus according to a second embodiment of the present invention; 
       FIG. 6A  is a view taken in the direction of arrow  6 A of  FIG. 5 , and  FIG. 6B  is a view taken in a direction of arrow  6 B of  FIG. 5  and showing a large rotary cam employed in the second embodiment; 
       FIG. 7  is a partly-sectional side view showing an impact test apparatus according to a third embodiment of the present invention; 
       FIG. 8  is a sectional view taken along line  8 - 8  of  FIG. 7 ; 
       FIG. 9  is a view showing a state when a relay member shown in  FIG. 7  has been moved in the third embodiment; 
       FIG. 10  is a sectional view taken along line  10 - 10  of  FIG. 9 ; and 
       FIGS. 11A and 11B  are schematic views showing a conventionally-known dent test apparatus. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Reference is now made to  FIGS. 1-3  showing an impact test apparatus according to a first embodiment of the present invention. The impact test apparatus  10  shown in  FIG. 1  includes: a base plate  11 ; support posts  12  supported on the base plate  11 ; a rotational drive unit  13  supported on the left support post  12 ; a brake  14  attached to a rear (left in  FIG. 1 ) end portion of the rotational drive unit  13 ; a speed reducer (transmission)  15  attached to a front (right in  FIG. 1 ) of the rotational drive unit  13  for reducing a rotational speed of the drive unit  13 ; a rotary cam  17  attached to a rotation shaft  16  extending from the speed reducer  15 ; a box frame  18  supported by the speed reducer  15  and right support post  12 ; bearing boxes  19  fixed to front and rear lower ends of the box frame  18 ; a pendulum arm support shaft  21  connected at its opposite ends to and extending between the bearing boxes  19 ; a pendulum arm  22  having a roller  22   c  provided on its proximal end portion  22   a  (see  FIG. 2 ) and held in abutting contact with the rotary cam  17 ; a hammer  23  attached to a distal end portion  22   b  of the pendulum arm  22 ; and a projection detecting sensor  24  provided in opposed relation to the rotary cam  17 . 
   The rotational drive unit  13  is preferably in the form of an electric motor, although it may be a rotary actuator, such as an air motor or hydraulic motor. 
   The speed reducer  15  is preferably in the form of reduction gears; for example, it may comprise a combination of a plurality of gears or a planetary gear speed reducer. 
   The projection detecting sensor  24  is preferably in the form of a proximity switch that detects metal pieces (later-described projections) through an eddy current action; alternatively, the number of rotation may be detected directly by a rotary encoder. 
   The brake  14 , rotational drive unit  13 , brake driver  25  and motor driver  26  are controlled by a test apparatus control unit  27 . For example, the test apparatus control unit  27  includes: a start switch  28 ; an operation lamp  29 ; a number-of-hitting setting dial  31 ; a set number-of-hitting display section  32 ; a number-of-rotation calculation section  33 ; an actual number-of-rotation display section  34  and a buzzer  35  that informs an end of the test. 
   As shown in  FIG. 2 , the rotary cam  17  has a plurality of projections  36   a ,  36   b ,  36   c  and  36   d  provided at equal angular pitches (e.g., 90° angular pitches). The rotary cam  17  is a disk-shaped cam that includes a large-diameter portion  17   a , a small-diameter portion  17   b , a diameter-changing portion  17   c  smoothly interconnecting the large- and small-diameter portions  17   a  and  17   b , and a stepped portion interconnecting the large- and small-diameter portion  17   a  and  17   b.    
   The box frame  18  includes an upper limit stopper  38  defining an upper limit of the pendulum arm  22 , and a lower limit stopper  39  defining a lower stopper of the pendulum arm  22 . 
   Next, with reference to  FIGS. 3A-3C , a description will be given about behavior of the first embodiment of the impact test apparatus  10  arranged in the aforementioned manner. 
   In  FIG. 3A , the proximal end of pendulum arm  22  is held in abutting contact with the large-diameter portion  17   a  of the rotary cam  17 , so that the pendulum arm  22  is held at a predetermined test start position (height). The projection detecting sensor  24  detects the projection  36   b . In these conditions, the rotary cam  17  is rotated in the counterclockwise direction at a predetermined speed. Then, once the roller  22   c , provided at the proximal end portion  22   a , shifts from the large-diameter portion  17   a  to the small-diameter portion  17   b , the roller  22   c  of the pendulum arm  22  is released, and thus, the pendulum arm  22  rotates in the counterclockwise direction about the pendulum arm support shaft  21 . Then, the hammer  23  hits the object of test  37 , as shown in  FIG. 3B . 
     FIG. 3C  shows the hammer  23  returning to its test start position after having hit the object of test. Because the rotary cam  17  has been rotated in the counterclockwise direction at the predetermined speed, the pendulum arm  22  is rotated back about the pendulum arm support shaft  21  through the diameter-changing portion  17   c  via the roller  22   c . As a consequence, the hammer  23  moves away from the object of test  37 . Once the projection  36   b  reaches a detecting range of the projection detecting sensor  24  as the rotary cam  17  further rotates back, the impact test apparatus is brought back to the conditions of  FIG. 3A . 
   Namely, one impact test is completed when the projection detecting sensor  24  has sequentially detected all of the four projections  36   a - 36   d.    
   The following lines describe an operational sequence of the impact test process. First, the human test operator sets a desired number of times of object-of-test hitting (e.g., five) by means of the number-of-hitting setting dial  31 . The thus-set number of object-of-test hitting is displayed on the display section  32 . 
   Then, once the test operator depresses the start switch  28 , the rotational drive unit  13  is activated to cause the rotary cam  17  to start rotating, so that the impact test is carried out in the manner as shown in  FIGS. 3A-3C . 
   During the impact test, the projection detecting sensor  24  sequentially detects the projections  36   a - 36   d . Each projection detection signal is sent to the number-of-rotation calculation section  33 . Once four projection detection signals are received from the sensor  24  in succession, the calculation section  33  judges that the single operational sequence of the impact test has been completed, assuming that one rotation of the rotary cam  17  has been made. Then, the number-of-rotation calculation section  33  causes the actual number-of-rotation display section  34  to display an accumulated number of rotation of the cam  17 . On the actual number of rotation display section  34 , any numerical value in a range of 0 (zero) to the operator-set value is displayed to inform the human test operator of a progress status of the test. Once the actual number of rotation of the rotary cam  17  reaches the operator-set value, the control unit  27  sounds the buzzer  35 , stops electric power supply to the rotational drive unit  13  and places the brake  14  in a braking state. 
   By the rotary cam  17  being rotated continuously at a predetermined speed, five impact tests, for example, can be carried out in succession. Thus, the human test operator only has to perform operation for starting the impact test, so that a load imposed on the test operator in connection with the impact tests can be significantly reduced. 
     FIG. 4  shows a number-of-hitting detection section  50  which detects the number of impact tests, i.e. which detects the number of object-of-detection hitting by detecting the number of rotation of the rotary cam  17 . 
   The number-of-hitting detection section  50  includes: the plurality of projections  36   a ,  36   b ,  36   c  and  36   d  provided on one side surface of the rotary cam  17 ; the projection detecting sensor  24  that sequentially detects these projections  36   a ,  36   b ,  36   c  and  36   d ; and the number-of-rotation calculation section  33  that calculates the number of rotation of the rotary cam  17  on the basis of detection information from the sensor  24 . 
     FIG. 5  shows an impact test apparatus  20  according to a second embodiment of the present invention, where the same elements as in the first embodiment of  FIG. 1  are indicated by the same reference characters and will not be described here to avoid unnecessary duplication. The second embodiment of the impact test apparatus  20  is similar to the above-described first embodiment but different therefrom in terms of structural arrangements within the box frame  18 . 
   Namely, in the second embodiment, the rotation shaft  16  in the first embodiment is replaced with a spline shaft on which is axially movably mounted a movable shaft  41 . Small and large rotation cam members  17   f  and  17   g  are mounted on the movable shaft  41  within the box frame  18 , and fork-shaped receiving flanges  43  are formed integrally with the movable shaft  41 . 
   Distal end portion  42   a  of a shift lever  42  is inserted between the fork-shaped receiving flanges  43 , and the shift lever  42  is pivotably supported by the box frame  18 . Knob  44  is provided on the proximal end of the shift lever  42 . 
     FIG. 6A  shows the small rotary cam member  17   f  of  FIG. 5 , while  FIG. 6B  shows the large rotary cam member  17   g  of  FIG. 5 . 
   In the state illustrated in  FIG. 5 , the large rotary cam member  17   g  contributes to the swinging movement of the pendulum arm  22 . As the human test operator operates the knob  44  to cause the shift lever  42  to pivot in the counterclockwise direction, the movable shaft  41  moves rightward as indicated by an imaginary line in  FIG. 5 . Then, the small rotary cam member  17   f  contributes to the swinging movement of the pendulum arm  22 , taking over the large rotary cam member  17   g.    
   In the aforementioned manner, there can be achieved an impact test apparatus which can perform impact tests of two different specifications. 
     FIGS. 7-10  shows an impact test apparatus  30  according to a third embodiment, where the same elements as in the first embodiment of  FIG. 1  are indicated by the same reference characters and will not be described here to avoid unnecessary duplication. The third embodiment of the impact test apparatus  30  is similar to the above-described second embodiment in that the small and large rotation cam members  17   f  and  17   g  are mounted within the box frame  18 , but different from the second embodiment in that these rotary cam members  17   f  and  17   g  are fixed to the rotation shaft  16  and a relay member  46  is disposed between the small and large rotation cam members  17   f  and  17   g  and the pendulum arm  22 . 
   The relay member  46  is connected to a shift shaft  47  which is in turn movably supported by the box frame  18  via bosses  48 . As the human test operator operates a knob  49  to cause the shift shaft  47  to move in a leftward/rightward direction of  FIG. 7 , the relay member  46  selectively abuts against the small or large rotation cam member  17   f  or  17   g.    
   As the large rotary cam member  17   g  rotates, the relay member  46  swings up and down about the shift shaft  47  and thereby causes the pendulum arm  22  to swing, as seen from  FIG. 8 . 
   Further, as the relay member  46  is shifted leftward, it abuts against the small rotary cam member  17   f , as seen in  FIG. 9 . 
   Furthermore, as the small rotary cam member  17   f  rotates, the relay member  46  swings up and down about the shift shaft  47  and thereby causes the pendulum arm  22  to swing, as seen from  FIG. 10 . 
   Whereas the third embodiment is shown in  FIGS. 7 and 9  as including just two rotary cam members  17  for convenience of explanation, it may include three or more rotary cam members  17  depending on the type of the object of test. With such three or more rotary cam members  17 , the third embodiment of the impact test apparatus can perform impact tests of a plurality of types of automotive vehicles, such as SUVs (Sports Utility Vehicles), sedans and sports cars, differing from one another in window inclination. 
   Obviously, various minor changes and modifications of the present invention are possible in light of the above teaching. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.