Abstract:
A panel-securing system for various vehicle types is provided, in which various clamps and fingers for different panel shapes may be selected for operation by a single cylinder, the amount of space utilized to install the system is minimized, and parts used in the system are simplified. The panel-securing system for use in a production line for various vehicle types comprises a controller having stored therein panel information for various vehicle types, the controller generating and outputting a locator-selection control signal and a panel-securing control signal corresponding to panel information of the correct vehicle type; a first actuator for selecting a locator corresponding to the locator-selection control signal output by the controller; a second actuator for driving a locator corresponding to the panel-securing control signal output by the controller; and a panel-securing assembly including a plurality of locators, which correspond to panels of the various vehicle types.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a panel-securing system for use in vehicle assembly lines, and more particularly, to a panel-securing system for various vehicle types. 
   BACKGROUND OF THE INVENTION 
   There are various types of securing systems used in vehicle assembly lines. For example, there is a mechanical securing system that uses clamps and fingers, and a suction-securing system that uses vacuum. In the case of the mechanical securing system, since the panels of doors and other such parts are not typically formed with flat surfaces, only a minimal securing area is available. Therefore, stable securing of panels is difficult. Also, because the position of the door panel is altered following the securing operation, the door panel must be put back into its original position, which is a difficult process. 
   As shown in  FIG. 1 , a conventional panel-securing system includes a jig-rotating cylinder  10 , a clamp cylinder  12 , a clamp  14 , and a locator  16 . Reference numerals  18  and  20  refer to a first hinge and a second hinge, respectively. In an initial state of the conventional panel-securing system, all jigs are reversely rotated by the release of the clamp  14 , resulting from the reverse positioning of the clamp cylinder  12  and by the shortening of the jig-rotating cylinder  10 . 
   In the case where a panel  22  of vehicle type A is handled, jigs of vehicle type A are advanced by the elongation of the jig-rotating cylinder  10 . With reference to  FIG. 2 , when the clamp cylinder  12  is operated, the clamp  14  approaches the panel  22 . With the continuing advancement of the clamp cylinder  12 , the clamp  14  locks onto the panel  22 , and the panel  22 , secured between the clamp  14  and the locator  16 , is transported to a desired location. 
   In the case of a handling jig mounted on a conventional robot arm or overhead loader, a variety of jigs must be installed in each location in order to secure various panels of differing shapes. A rotating structure therefore must be implemented to prevent interference between the panel and jig. As a result, the overall structure becomes complicated and the assembly has significant weight. For example, in the case of a handling jig used in a door line of an assembly process that produces three different types of vehicles, three different types of jigs must be provided at each master control point as shown in FIG.  3 . 
   It is therefore necessary, with the conventional panel-securing system for various vehicle types, to use a different set of clamps and fingers for every type of vehicle, as well as separate cylinders to drive the clamps and fingers. The large number of clamps, fingers and cylinders increases overall manufacturing cost and requires crowding of parts into small areas. Further, a shut-down period is required when changing vehicle type so that changes in the securing system can be made. Finally, the conventional panel-securing system is slow in operation as a result of its increased weight, thereby slowing the overall production process. 
   SUMMARY OF THE INVENTION 
   The present invention provides a panel-securing system for various vehicle types in which various clamps and fingers for different panel shapes may be selected for operation by a single activator, such as a cylinder. According to a preferred embodiment, a panel-securing system for use in a production line for various vehicle types comprises a controller, a panel-securing assembly and first and second actuators. The controller has stored therein panel information for various vehicle types. The controller generates and outputs a locator-selection control signal and a panel-securing control signal corresponding to panel information of the correct vehicle type. The panel-securing assembly includes a plurality of locators, which correspond to panels of the various vehicle types. The first actuator selects a locator corresponding to the locator-selection control signal output by the controller. The second actuator drives a locator corresponding to the panel-securing control signal output by the controller. 
   In an alternative embodiment of the present invention, a panel securing system includes a plurality of panel locators with each locator having a locating portion configured and dimensioned to mate with a specific panel type. The locating portion is formed on a locator body and defines a hole therethrough, including an indexing notch. A rotatable first shaft passes through the panel holes. An indexing clamp is disposed on the shaft and translatable along the shaft in response to rotation thereof. A second shaft surrounds the first shaft and defines a longitudinal groove with the indexing clamp extending through the groove. The indexing clamp is positionable in a specific indexing notch in response to rotation of the first shaft in order to select a specific panel locator. The selected panel locator is then actuatable via the indexing clamp in response to rotation of the second shaft. Preferably the rotatable first shaft comprises a lead screw. Also, biasing elements acting on the panel locators to bias the locators against the second shaft may be provided. 
   In a further preferred alternative embodiment, the system further includes a servo motor cooperating with the first shaft to rotate the first shaft and a hydraulic cylinder and linkage cooperating with the second shaft to rotate the second shaft. An electronic control unit may be provided to control the servo motor and hydraulic cylinder based on panel selection and actuation signals. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention, and, together with the description, serve to explain the principles of the invention: 
       FIG. 1  is a schematic view of a conventional panel-securing system for various vehicle types; 
       FIG. 2  is a schematic view of the panel-securing system of  FIG. 1  in operation; 
       FIG. 3  is a schematic view showing the placement of a variety of conventional panel-securing systems to enable operation on a specific number of vehicle types; 
       FIG. 4  is a schematic view illustrating mounting positions of a panel-securing system for various vehicle types according to a preferred embodiment of the present invention; 
       FIG. 5  is an exploded perspective view of a panel-securing system for various vehicle types according to a preferred embodiment of the present invention; 
       FIGS. 6-8  show different perspective views of the panel-securing system of  FIG. 5  in an assembled state; 
       FIG. 9  is a partially disassembled perspective view of the panel-securing system of  FIGS. 6-8  used to describe a connection between a clamp and a locator; 
       FIG. 10  is a partially disassembled perspective view of the panel-securing system of  FIGS. 6-8  used to describe a connection between a locator and an elastic element; 
       FIG. 11  is a schematic perspective view of the panel-securing system of  FIG. 5  in an assembled state showing the operation of a locator corresponding to the driving of the panel-securing system; and 
       FIG. 12  is a process flow diagram of the operation of a panel-securing system for various vehicle types according to a preferred embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. 
   Referring to  FIGS. 4 and 5 , a system for securing a panel for various vehicle types in a vehicle production line according to a preferred embodiment of the present invention includes a controller  100 , a first actuator  110 , a second actuator  120 , and a panel-securing assembly  130 . 
   The controller  100  has stored therein panel information regarding various vehicle types, and, using this information, performs overall control of the panel-securing system. In particular, the controller  100  generates a locator-selection control signal and a panel-securing control signal corresponding to panel information for the correct vehicle type. In addition, the controller  100  preferably includes a separate memory portion, in which there is stored panel information according to vehicle type. The controller  100  may be a microprocessor and may use a server or a typical personal computer in the assembly line. 
   The first actuator  110  selects a locator (shown in  FIG. 5 ) that corresponds to the panel information supplied by the locator-selection control signal received from the controller  100 . The first actuator  110  comprises a servomotor having a rotating spindle. The second actuator  120  drives the locator corresponding to the panel-securing control signal received from the controller  100 . The second actuator  120  comprises a hydraulic cylinder having a rod  122  that undergoes rectilinear motion during operation. 
   As shown in  FIG. 5 , the panel-securing assembly  130  includes a plurality of locators  136  corresponding to panels of various vehicle types. The assembly cooperates with the first and second actuators  110  and  120  such that the locator corresponding to the panel information is driven. The panel-securing assembly  130  includes a main body frame  131  and an auxiliary body frame  132 , a first shaft  133 , a clamp  134 , a second shaft  135 , and locators  136 . There are as many locators  136  as there are a number of vehicle types that are applied to the production line. In a preferred embodiment of the present invention, there are five locators  136  to handle five different vehicle types. 
   The second actuator  120  is mounted to the main body frame  131  and the first actuator  110  is mounted to the auxiliary body frame  132 . The main body frame  131  and the auxiliary body frame  132  are connected, preferably by bolts. That is, the auxiliary body frame  132  is placed on an extended portion of the main body frame  131  and bolted thereon. 
   The first shaft  133  comprises a ball screw mechanism wherein the lead screw is rotated by the first actuator  110 . The clamp  134  is driven linearly along the axis of first shaft  133  by the lead nut in response to rotation of the first shaft  133 . Clamp  134  may be formed as part of or separate from the lead nut. Rotation of first shaft  133  causes the clamp to be linearly positioned in association with a selected locator based on the panel information from controller  100 . Clamp  134 , driven by second shaft  135  as explained below, then rotates together with the selected locator  136 . Hence, the clamp  134  functions to actuate the locators  136 . In a preferred embodiment of the present invention, clamp  134  acts similarly to a clutch that operates to rotate only the one of the locators  136  that is selected. 
   The second shaft  135  is preferably substantially cylindrical and is rotated by second actuator  120 . Rod  122  of the second actuator  120  is linked to second shaft  135  by a level arm or other substitute linkage such that rectilinear motion of rod  122  rotates the second shaft  135 . The first shaft  133  is inserted inside the second shaft  135  along the longitudinal axis thereof, and a groove is formed in the second shaft  135  along the length thereof so that the clamp  134  can protrude past the second shaft  135  to perform its operation. 
   The locators  136  are connected to the second shaft  135  as described below. Each locator  136  includes a body plate  140  having a mounting hole  142  through which the second shaft  135  passes for mounting thereon. A clamp groove  144  is formed into the body plate  140  in an upper portion of the circumference of the mounting hole  142  (as in FIG.  5 ). Clamp  134  connects with the clamp groove  144  of the selected locator  136  when moved along the first shaft  133 . Panel-securing members  146  are formed extending from an upper portion of the body plate  140 . Bushing  147  is inserted in the mounting hole  142 , and weight plate  149  is at one side of each body plate  140 . 
   The panel-securing assembly  130  further includes a power transmitter  150 . The power transmitter  150  preferably includes a first pulley  152 , which is connected to a spindle of the first actuator  110 , and a second pulley  154  connected to an end of the first shaft  133 . Drive belt  156  cooperates between the first and second pulleys  152  and  154  such that a torsional force of the first actuator  110  is transmitted to the first shaft  133 . Reference numeral  158  indicates a cover that protects the drive belt  156 . 
   The panel-securing assembly  130  further includes a position-adjusting member  160 . The position-adjusting member  160 , in a state where locator  136  is connected to the second shaft  135 , applies a predetermined elastic force in a direction toward the locators  136  such that the locators  136  maintain their state of connection to the second shaft  135 . The position-adjusting member  160  includes housings  162 , a support block  164 , elastic elements  166 , and guides  168 . 
   Each of housings  162  is mounted to contact to a lower portion of one of the locators  136  when the locators  136  are mounted on the second shaft  135 . Housings  162  are cylindrical and hollow, and one end of housings  162  is closed. The closed ends of each housing have a larger diameter than the rest of the housings. Also, screw threads are formed on an inner surface of housings  162 . 
   The support block  164  is connected to the body frames  131  and  132  of the panel-securing assembly  130  in a direction substantially parallel to the first shaft  133 . The support block  164  is preferably hexahedral and includes holes into which housings  162  are inserted. 
   Elastic elements  166  are provided between the housings  162  and the support block  164 . Elastic elements  166  are preferably compression coil springs. Housings  162  are inserted within the elastic elements  166  with one end of elastic elements  166  abutted against the closed ends of each housing  162 , and opposite ends of the elastic elements  166  abutted against the support block  164 . The elastic elements  166  act to fix the locators  136  in a horizontal direction. 
   Guides  168  are inserted into the holes formed in the support block  164 , and the housings  162  are inserted into the same holes of the support block  164  as described above with the guides  168  interposed therebetween. Bolts  170  are screwed into the threads of the housings  162  such that the housings  162  are secured in their positions within the holes of the support block  164  but are able to undergo sliding motion therein in the longitudinal direction of the housings  162 . The guides  168  act to guide the housings  162  during their sliding motion. 
   Reference numeral  148  of  FIG. 5  indicates a protrusion formed at a bottom portion (in the drawing) of the locators  136 . In an assembled state, the housings  162  contact the protrusions  148  of the locators  136 . 
   Operation of the panel-securing system according to a preferred embodiment of the present invention will now be described with reference to  FIGS. 6-12 . 
   As discussed above, the panel-securing system according to a preferred embodiment of the present invention is structured to select the locators  136  using a single actuator. The selected locator  136  is then operated using a different actuator. A swing operation of one of the locators  136  corresponding to vehicle type, information of which is received from the controller  100 , will first be described. 
   As shown in  FIG. 12 , the controller  100  supplies a locator-selection control signal to the first actuator  110  (servo motor) in step  1 . Next, the first actuator  110  rotates according to the input of the locator-selection control signal received from the controller  100  in step  2 . As a result, the first pulley  152  of the power transmitter  150  rotates by its connection to the first actuator  110 , which, in turn, rotates the second pulley  154  via the drive belt  156 . 
   The first shaft  133  then rotates through its connection to the second pulley  154 . Therefore, the clamp  134  is moved along the first shaft  133 . The distance that the clamp  134  moves is controlled by the locator-selection control signal supplied to the first actuator  110 . That is, the first actuator  110  rotates by an amount corresponding to the locator-selection control signal, and the clamp  134  moves along the first shaft  133  according to the degree to which the first actuator  110  rotates. As a result, the clamp  134  comes to be positioned at the locator  136  corresponding to the locator-selection control signal and connection between the clamp  134  and the clamp groove  144  occurs, thereby completing locator selection in step  3 . 
   In this state, a panel-securing control signal is supplied to the second actuator  120  from the controller  100  such that the second actuator  120  is operated in step  4 . With the operation of the second actuator  120 , the rod  122  of the second actuator  120  is extended such that the second shaft  135  undergoes rotation in step  5 . This results in the rotation of the locator  136  connected to the clamp  134  in step  6 . Hence, only the locator corresponding to the panel of the correct vehicle type is selected and operated such that the securing of panels of various vehicle types is possible. 
   With the use of the panel-securing system for various vehicle types of the present invention described above, it becomes unnecessary to stop the production line for the changing of jigs since the securing system may be used for multiple types of panels. Also, the number of jigs is reduced and the jig parts are made simpler such that overall production is simplified and panel-securing is made more efficient. 
   Further, because the number of cylinders is reduced, the cost and weight of the panel-securing system are significantly reduced, and maintenance is required less frequently. 
   Although preferred embodiments of the present invention have been described in detail hereinabove, it should be clearly understood that many variations and/or modifications of the basic inventive concepts herein taught which may appear to those skilled in the present art will still fall within the spirit and scope of the present invention, as defined in the appended claims.