Patent Publication Number: US-7213803-B2

Title: Clamp and method for operating same

Description:
BACKGROUND 
     In many manufacturing operations, newly manufactured parts need to be tested to ensure that the new parts have been manufactured according to the design specifications and to ensure that the new parts perform as expected under specific test conditions. A wide variety of test equipment and instrumentation is utilized to test such newly manufactured parts. 
     When testing such parts, it is often necessary to securely hold or clamp the newly manufactured parts to test apparatus for a short period of testing. For example, in the electronics industry, an electronic device will need to be clamped to a tester so that the tester can test the electronic device. The clamping must be accomplished in such a way as to allow various probes on the tester to reliably contact various circuit nodes and contacts provided on the electronic device. Testing operations can be enhanced by clamping systems that can quickly and accurately clamp and release the electronic device to be tested. 
     SUMMARY OF THE INVENTION 
     In one embodiment, a clamp comprises a frame and a latch member mounted within the frame so that the latch member is translatable along a displacement axis and rotatable about the displacement axis. A guide pin mounted to the frame engages a channel operatively associated with the latch member. An actuator mounted to the frame and operatively associated with the latch member translates the latch member along the displacement axis. The engagement of the guide pin and channel causes the latch member to be rotated about the displacement axis as the latch member is translated along the displacement axis. 
     In another embodiment, a method for operating a clamp comprises: operating an actuator to cause a latch member to translate along a displacement axis toward an extended position, the latch member cooperating with a guide pin associated with the clamp so that the latch member rotates about the displacement axis as the latch member is translated along the displacement axis; engaging a clamp end of the latch member with a component to be clamped; and operating the actuator to cause the latch member to translate along the displacement path toward a retracted position, the guide pin causing the latch member to rotate about the displacement axis as the latch member is translated along the displacement axis to the retracted position, the rotation and translation of the latch member causing the clamp end of the latch member to clamp the component and draw the component toward the retracted position. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Illustrative and presently preferred exemplary embodiments of the invention are shown in the drawings in which: 
         FIG. 1  is a perspective view of one embodiment of a clamp; 
         FIG. 2  is an exploded perspective view of the clamp of  FIG. 1 ; 
         FIG. 3  is an enlarged perspective view of the clamp showing the engagement of the guide pin and channel; and 
         FIGS. 4A ,  4 B and  4 C are perspective sequential views of one operational mode of the clamp. 
     
    
    
     DETAILED DESCRIPTION 
     One embodiment of a clamp  110  is illustrated in  FIGS. 1 and 2  and comprises a frame  112 , and a latch member  114  mounted within the frame  112 . The mounting arrangement of the latch member  114  within the frame  112  allows the latch member  114  to be translated along a displacement axis  116 , i.e., generally in the directions indicated by arrows  118 . The mounting arrangement also allows the latch member  114  to be rotated about the displacement axis  116 , i.e., generally in the directions indicated by arrows  120 . A guide pin  122  mounted to the frame  112  engages a corresponding channel  124  associated with the latch member  114 . An actuator  126  is mounted to the frame  112  and is operatively associated with the latch member  114 . The actuator  126  moves or translates the latch member  114  along the displacement axis  116 . As the latch member  114  is translated along the displacement axis  116 , i.e., in the directions indicated by arrows  118 , the engagement of the guide pin  122  and the channel  124  causes the latch member  114  to be rotated about the displacement axis  116 , i.e., in the directions indicated by arrows  120 . In one embodiment, the clamp  110  is provided with a biasing member  144 , such as a spring  146 , which biases the latch member  114  toward a retracted position  140 . 
     The rotation of the latch member  114  about the displacement axis  116  as the latch member  114  is translated along the displacement axis  116  allows the clamp  110  to engage and securely hold a component  128  to be clamped. With reference now to  FIGS. 4A–C , in one exemplary application, the component  128  to be clamped may comprise a portion  130  having an aperture or hole  132  formed therein. The aperture  132  is sized to slidably receive a clamp end  134  of the latch member  114  when the latch member  114  is in an extended position  136 . See  FIG. 4A . When the latch member  114  is in the extended position  136 , the clamp end  134  of the latch member  114  will be located at a displaced rotational position  138 . The component  128  to be clamped and the clamp  110  may then be brought together in the manner illustrated in  FIG. 4B , e.g., so that the clamp end  134  of latch member  114  is engaged with and extends through the aperture  132  in the component  128  to be clamped. 
     The actuator  126  may then be operated to cause the latch member  114  to be translated along the displacement axis  116 , e.g., from the extended position  136  to the retracted position  140 . In the embodiment shown and described herein wherein the clamp  110  is provided with a biasing member  144 , the latch member  114  may be moved from the extended position  136  to the retracted position  140  by simply de-energizing the actuator  126  and allowing the biasing member  144  to return the latch member  114  to the retracted position  140 . As the latch member  114  returns to the retracted position  140 , the engagement of the guide pin  122  with the channel  124  causes the latch member  114  to rotate about the displacement axis  116 , e.g., from the displaced rotational position  138  to an initial rotational position  142 . The translation and rotation of the latch member  114  causes the clamp end  134  of the latch member  114  to clamp the component  128  and draw the component  128  toward the retracted position  140 , as best seen in  FIG. 4C . In the embodiment shown and described herein, the biasing member  144  (e.g., spring  146 ) securely holds the component  128  in engagement with the clamp  110  without the need to further operate the actuator  126 . 
     One aspect of the clamp  110  is that clamping is achieved using only a single actuator  126  to produce two desired movements of the latch member  114  (i.e., translation along and rotation about the displacement axis  116 ). The use of a single actuator  126  to produce the two desired movements of the latch member  114  also eliminates the need for a timing sequence to coordinate the two desired movements which would be required if separate actuators were used to produce the two desired movements. In addition, the modular design of the clamp  110  allows the clamp  110  to be conveniently mounted almost anywhere. The modular design also allows any desired number of clamps to be readily used in a desired application. In embodiments wherein the clamp  110  is provided with a biasing member  144  (e.g., spring  146 ), the biasing member  144  may be configured to bias the clamp in the retracted position  140  ( FIG. 4C ). Accordingly, the clamp  110  will continue to provide the clamping function without the need to continuously operate or energize the actuator. 
     Having briefly described one embodiment of a clamp, various exemplary embodiments of the clamp will now be described in greater detail. However, before proceeding with the description it should be noted that the various embodiments of the clamp  110  are shown and described herein as they may be used to provide a clamping function in a circuit testing application. In this exemplary application, the clamp  110  is mounted to a circuit test head and the component  128  to be clamped comprises an electronic device to be tested. The clamp  110  is used to clamp the electronic device to the circuit test head, allowing the test head to test the electronic device. Accordingly, the particular sizes and configurations of the various components of the clamp  110 , as well as the materials that may be used to fabricate the various components are consistent with this particular application. However, persons having ordinary skill in the art, after having become familiar with the teachings provided herein, will recognize that various modifications may be made to the clamp depending on the particular application. 
     Referring back now primarily now to  FIGS. 1 and 2 , one embodiment of a clamp  110  may comprise a frame  112  configured to receive a latch member  114 . The frame  112  and latch member  114  are configured so that the latch member  114  is translatable and rotatable about a displacement axis  116 , as indicated by arrows  118  and  120 , respectively. Accordingly, the frame  112  may comprise any of a wide variety of structures and configurations suitable for this purpose. However, by way of example, in the embodiment shown and described herein, the frame  112  may comprise an upper plate  148  and a lower plate  150  that are positioned in spaced-apart relation by a plurality of elongate rods  152 , as best seen in  FIG. 1 . 
     The various components, such as upper plate  148 , lower plate  150 , and elongate rods  152 , comprising the frame  112  may be fabricated from any of a wide variety of materials, such as metals, plastics, or combinations thereof, suitable for the intended application. However, by way of example, in one embodiment, the upper and lower plates  148  and  150 , as well as the elongate rods  152 , are fabricated from aluminum. 
     In one embodiment, the upper plate  148  is provided with a bearing member  170  ( FIG. 3 ) suitable for allowing both axial and radial (i.e., rotational) movement of the latch member  114  with respect to the upper plate  148 . Alternatively, a separate bearing member  170  may not be required, depending on the particular application. For example, the particular materials used for the latch member  114  and upper plate  148  may or may not indicate the need for a separate bearing member  170 . Similarly, a separate bearing member  170  may not be required if the expected loads are small or if the expected number of cycles during the life of the clamp is low. If a separate bearing member  170  is used, bearing member  170  may comprise any of a wide range of bearing types suitable for the intended application. By way of example, in the embodiment shown and described herein, bearing member  170  comprises a bronze bushing sized to slidably and rotatably receive the latch member  114  in the manner described herein. 
     Latch member  114  is best seen in  FIG. 2  and may comprise an elongate shaft  154  having a flange end  156  and a clamp end  134 . The clamp end  134  may be provided with a boss or clamp member  160  suitable for engaging the aperture  132  provided in the component  128  to be clamped. See  FIGS. 4A–C . Accordingly, the clamp member  160  may comprise any of a wide variety or shapes or configurations and should not be regarded as limited to the particular shape shown and described herein. The clamp member  160  may comprise a separate component that is attached to the elongate shaft  154 , as best seen in  FIG. 2 . Alternatively, the clamp member  160  could be formed as a single piece (i.e., integral) with elongate shaft  154 . 
     Referring now primarily to  FIG. 3 , elongate shaft  154  may also be provided with a channel or groove  124  therein sized to engage the guide pin  122 . The channel or groove  124  may be provided with a first section  162  that is substantially axially oriented along the length of the elongate shaft  154 . The channel or groove  124  may also be provided with a second section  164  that includes a transverse component (i.e., a component that is not substantially axially oriented). The length  166  of the first section  162  dictates the length or distance by which the latch member  114  moves along the displacement axis  116  before the latch member  114  begins to rotate. Thus, the length  166  of the first section  162  of channel  124  may be selected to be any convenient length suitable for the intended application. 
     The length  168  of the second section  164  dictates the length or distance by which the latch member  114  moves along the displacement axis  116 , as well as the degree of rotation about the displacement axis  116 . Thus, the motion “schedule” (i.e., the length by which the latch member moves along the displacement axis  116 , the degree of rotation about the displacement axis  116 , as well as the point at which rotation begins) can be selected as desired by simply providing the channel  124  with first and second sections  162  and  164  having the appropriate lengths and transverse components. Consequently, the latch member  114  should not be regarded as limited to having a groove or channel  124  having first and second sections  162  and  164  that provide the particular motion schedule shown and described herein. However, by way of example, in one embodiment, the groove or channel  124  is configured to provide a total axial (i.e., translational) movement along the displacement axis  116  of about 5.0 millimeters. The groove or channel  124  is configured to provide total rotational movement about the displacement axis  116  (i.e., the angular difference between the displaced rotational position  138  and the initial rotational position  142 ) of about 45°. In an alternative embodiment, the channel  124  is configured to provide a total rotational movement of about 90°. 
     The various components comprising the latch member  114  may be fabricated from any of a wide variety of materials, such as metals, plastics, or combinations thereof, suitable for the intended application. However, by way of example, in one embodiment, the elongate shaft  154  as well as the clamp member  160  are fabricated from a steel. 
     Guide pin  122  may be mounted to the frame  112  at any convenient position that will allow the guide pin  122  to engage the channel  122  associated with the latch member  114 . However, by way of example, in one embodiment, the guide pin  122  is mounted to the upper plate  148  of frame  112  in the manner best seen in  FIG. 3 . 
     Guide pin  122  may be fabricated from any of a wide range of materials, such as metals or plastics, suitable for the intended application. However, it is generally preferred that the material used to fabricate the guide pin  122  provide a low-friction engagement with the material selected for the elongate shaft  154  in which the channel  124  is formed. Thus, in the embodiment shown and described herein wherein the elongate shaft  154  comprises steel, the guide pin  122  is fabricated from bronze. Optionally, a suitable lubricant may also be provided to further ensure a low-friction engagement of the guide pin  122  and channel  124 . 
     Before proceeding it should be noted that the positions of the guide pin  122  and the channel  124  could be interchanged. That is, the guide pin  122  could be mounted to the latch member  114  and the channel  124  provided on the frame  112 . Still other arrangements are possible, as would become apparent to persons having ordinary skill in the art after having become familiar with the teachings provided herein. 
     Referring back now to  FIGS. 1 and 2 , the clamp  110  may also be provided with an actuator  126  suitable for moving the latch member  114  along the displacement axis  116  in the manner described herein. The actuator  126  may comprise any of a wide range of actuators (e.g., pneumatic, hydraulic, or electric) suitable for providing the desired magnitude (i.e., length) of motion of the latch member  114  along the displacement axis  116 . However, by way of example, in one embodiment, the actuator  126  comprises a pneumatic actuator. 
     In the embodiment shown and described herein, a push plate  172  is positioned between the actuator  126  and the latch member  114 . The push plate  172  is slidably mounted to the rods  152  of the frame  112  and serves to support the flange end  156  of the latch member  114  as well as to distribute the force applied by the actuator  126 . Consequently, the push plate  172  helps to prevent binding of the latch member  114  as the same is moved between the retracted position  140  and the extended position  136  (See  FIGS. 4A–C ). The push plate  172  may be fabricated from any of a wide variety of materials (e.g., metals or plastics) suitable for the intended application. By way of example, in one embodiment the push pate  172  is fabricated from steel. 
     In the embodiment shown and described herein, the clamp  110  is also provided with a biasing member  144  which biases the latch member  114  in the retracted position  140 . The use of the biasing member  144  thereby allows the clamp  110  to exert a clamping force on the component  128  ( FIGS. 4A–C ) being clamped without the need to operate (e.g., continuously energize) the actuator  126 . The biasing member  144  may comprise a coil spring  146  having a first end  174  positioned in contact with the upper plate  148 . A second end  176  of spring  146  is received by a lower support  178 . Lower support  178  is configured to contact the push plate  172  in the manner best seen in  FIG. 2 . 
     Spring  146  and lower support  178  may be fabricated from any of a wide variety of materials, such as metals or plastics, suitable for the particular application. By way of example, in one embodiment, spring  146  comprises steel, whereas lower support  178  comprises aluminum. 
     It should be noted that if a biasing member  144  is provided, it may be configured or arranged to bias the latch member  114  in either the retracted position  140  or the extended position  136 . If the biasing member  144  is configured to bias the latch member  114  in the extended position  136 , then continuous operation of the actuator  126  will be required to maintain clamping of the component  128  to be clamped, which may be required or desired depending on the particular application. 
     Referring now primarily to  FIG. 2 , the clamp  110  may be provided with a bearing  180  suitable for receiving the flange end  156  of the elongate shaft  154 . The bearing  180  supports the flange end  156  of the elongate shaft  154  and allows the elongate shaft  154  to be rotated with respect to the push plate  172 . In the embodiment shown and described herein, the bearing  180  is captured or held between the lower support  178  and push plate  172 . In this manner, the bearing  180  retains the flange end  156  of the elongate shaft  154  so as to enable a transfer of the clamping force applied by the biasing member  144  to both the shaft  154  and clamp member  160 . Lower support  178  may be provided with a suitable recess (not shown) therein to receive the bearing  180 . 
     Bearing  180  may comprise any of a wide range of bearing types, depending on the particular application. However, by way of example, in one embodiment, bearing  180  may comprise a cross roller bearing. 
     Clamp  110  may be used in any of a wide variety of applications to clamp or secure a component  128  to be clamped. Consider, for example, the situation illustrated in  FIGS. 4A–C  wherein the component  128  to be clamped comprises a portion  130  having an aperture or hole  132  formed therein. The aperture  132  is sized to slidably receive the clamp end  134  provided on the latch member  114  when the clamp end  134  is in the displaced rotational position  138 . As mentioned, the clamp end  134  of latch member  114  is in the displaced rotational position  138  when the latch member  114  is in the extended position  136 . See  FIG. 4A . Accordingly, a first step in the clamping process involves operating the actuator  126  to move the latch member  114  to the extended position  136 . The component  128  to be clamped and the clamp  110  may then be brought together in the manner shown in  FIG. 4B , i.e., so that the clamp end  134  of latch member  114  is engaged with and extends through the aperture  132  in the component  128  to be clamped. 
     The actuator  126  may then operated to cause the latch member  114  to be translated along the displacement axis  116 , e.g., from the extended position  136  to the retracted position  140  illustrated in  FIG. 4C . The latch member  114  may be moved from the extended position  136  to the retracted position  140  by operating the actuator  126  to return the latch member  114  to the retracted position  140 . In the embodiment shown and described herein wherein the clamp  110  includes a biasing member  144  for biasing the latch member  114  toward the retracted position  140 , the latch member  114  may be returned to the retracted position  140  by simply de-energizing the actuator  126 . In the case where the actuator  126  comprises a pneumatic actuator, this can be accomplished by simply releasing the air pressure supplied to the actuator  126 . As the latch member  114  moves to the retracted position  140 , the engagement of the guide pin  122  with the channel  124  causes the latch member  114  to rotate about the displacement axis  116 , e.g., from the displaced rotational position  138  to the initial rotational position  142 . The translation and rotation of the latch member  114  causes the clamp end  134  of the latch member  114  to clamp the component  128  and draw the component  128  toward the retracted position  140 , as best seen in  FIG. 4C ). The biasing member  144  (e.g., spring  146 ) securely holds the component  128  in engagement with the clamp  110  without the need to further operate the actuator  126 . 
     The component  128  to be clamped may be released by operating the actuator  126  to move the latch member  114  to the extended position  136 . As the latch member  114  moves to the extended position, the engagement of the guide pin  122  and the channel  124  causes the latch member  114  to be rotated from the initial rotational position  142  ( FIG. 4C ) to the displaced rotational position  138  ( FIG. 4A ), thereby allowing the component  128  to be disengaged from clamp  110 .