Abstract:
A registration alignment system to be used with a printed circuit board drilling machine for registration of PCBs on the tooling plate for drilling and other operations. The registration alignment system includes a registration bar and a registration block that move independently of each other. The movement of the registration bar is constrained to one dimension (i.e., X-axis), and the movement of the registration block is constrained to one dimension (i.e., Y-axis) that is perpendicular to the axis of movement of the registration bar. The registration bar and block contact adjusting screws which are used to control precise movement of the registration bar and block. When the registration pins of the PCB are in position against the registration bar and block, the pins are held in place by clamping bars. When the size of the registration pins change, the registration of the new PCB is still correct and does not have to be adjusted.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The field of this invention relates to registration devices used for positioning work pieces on a worktable and holding the same in place while the work piece is operated on. More particularly, this invention relates to registration devices that are attached to the tooling plate of the work tables of numeric controlled machine tools to register printed circuit boards and other work pieces for drilling or other machine operations. 
     2. Description of the Related Art 
     Printed Circuit Board (PCB) drilling machines are typically computer controlled machines having a table that moves in any X, Y plane, and a spindle that moves perpendicular to the table in the Z direction to drill holes in the PCB. One or more plates are mounted on the X, Y table, commonly called tooling plates, onto which stacks of one or more PCBs are placed. PCBs come in a variety of lengths, widths and thickness. However, PCBs always have at least two registration pins which are mounted in or through the PCB, so that the pins can be used to precisely mount the board into a known position after the board has been manually or automatically loaded onto the tooling plate. The tooling plate uses clamps and a registration bar, both of which are securely mounted on the plate, and are used to register the PCB with the drilling machine. The clamps are moving parts that are biased against the pins and hold the pins in place against the registration bar. 
     The registration pins are typically located at the center of two opposite edges of the PCB. In one common registration method as illustrated in FIGS. 8A and 8B, referred to as V-registration, the first registration pin  310  is held into place in a V-shaped registration block  125   a  at the end of a registration bar. The second pin  320 , also referred to as the anti-rotation pin, is held against the registration bar by an elongated clamping bar (not shown). The registration block may be attached or separated from the registration bar. The V-shaped end of the registration bar is aligned to the drilling machine, so that the lead pin can be used as a starting dattuin for creating a drilling program for the PCB. The trailing pin is aligned with the lead pin, so that the centerline formed by the centers of the two registration pins is parallel with the registration bar. 
     The diameter of the registration pins is dependent on the thickness of the PCB. In use the V shaped clamping mechanism receives different diameter registration pins which occupy different positions within the V and maintain the same centers. However, different diameter pins create a problem, because different diameter registration pins can result in a misalignment of the registration pins and the anti-rotation pin leading to random registration errors. The first registration pin with the new diameter will still align its center properly in the V-shaped end of the registration bar because the V shape maintains axial alignment, but the trailing anti-rotation pin is aligned to the registration bar on one side thereof. Accordingly, the anti-rotation pin will extend away from the registration bar by its radius and not its axis, such that the centerline between the lead and trailing pins axes will be skewed so that the centerline is no longer parallel to the registration bar. The registration errors are detectable in the sub-micron level precision required for the accurate drilling of PCBs and holes will be drilled in the wrong locations. 
     In order to properly register the PCB with the drilling machine, the registration bar and in some cases the registration block needs to be adjusted in the tooling plate by moving in the X and Y dimension the registration block in the X and Y dimension so that the centerline formed by the two registration pins will be parallel to the registration bar. This adjustment must be made each time a different diameter registration pin is used. Because the tooling plate is heavy, and therefore difficult to move in the small distances that are required to calibrate the registration bar and the registration block with the drilling machine, a tedious, time-consuming manual alignment process that must occur whenever a PCB with a different registration pin size is loaded onto the drilling machine. If the registration block is attached to the end of the registration bar, alignment is even more difficult. 
     For the foregoing reasons, there is a need for a registration system that will eliminate the registration errors introduced by misalignment of the PCB when the registration pin size changes. 
     SUMMARY 
     The present invention is directed to registration devices that permit accurate registration of a PCB to a drilling machine without the need to recalibrate the registration surfaces each time a registration pin diameter change occurs. The registration alignment system of the instant invention comprises a tooling plate that has a channel and a registration bar and registration block that are mounted in the channel. The registration bar and registration block are each constrained to move in different directions. The registration bar moves along the X-axis and the registration block moves perpendicular to the X-axis, along the Y-axis. The registration bar and registration block are spaced apart so that they can be moved independently. There is at least one first adjustable mechanism for engaging and moving the registration bar. The adjusting mechanism is coupled to the registration bar such that it can be used to control precise movement of the registration bar. An adjusting screw is used for the first adjustable mechanism and the adjusting screw can be turned by hand or by tool. Once the registration bar is in the proper calibrated location, it is secured to the tooling plate by mounting screws. Similarly, there is at least one second adjustable mechanism for moving the registration block. This second adjustable mechanism is also coupled to the registration block such that it can be used to control precise movement of the registration block and is also an adjusting screw. 
     The object of this invention is to provide a convenient, simple, easy and accurate means for registration of a PCB on a machine that operates on the PCB. 
     This is extremely important in the context of machine drilling holes in PCBs, as very fine accuracy is required due to the high density of electrical components that are mounted on PCBs. 
     One feature of the present invention is the design of the registration block that accommodates any size diameter registration pin without the need for re-calibration. 
     Another feature of the present invention is the ability to move the registration bar and registration block independent of each other. 
     Still another feature of the present invention is the design of the adjusting mechanisms so that the registration bar and registration block can be easily moved in micro increments. In the present invention, the registration bar and registration block can be easily moved by hand in controlled, precise movements. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will be described herein in conjunction with the appended drawing figures, wherein like numerals denote like elements, and: 
     FIG. 1 is a top view of a manual registration pin alignment system according to the present invention. 
     FIG. 2 illustrates a perspective view of a PCB with two registration pins; 
     FIG. 3 is a detailed top view of part of the system of FIG. 1, depicting a registration pin in position for registration 
     FIG. 4 is a close up view of the clamping mechanism in an open position including the operating activator; 
     FIG. 5 is a close up view of the clamping mechanism in a closed position including the operating activator; 
     FIG. 6 is a view of registration pin and clamping cam; 
     FIG. 7 is a view of registration pin in registration position engaged by clamping cam; 
     FIGS. 8A and 8B are views of the prior art device. 
    
    
     DETAILED DESCRIPTION 
     The invention provides a manual registration pin alignment system for positioning printed circuit boards (PCB) and other work pieces for drilling or other machine operations. The invention could be used to position a variety of work pieces for drilling or other operations, but the invention is particularly suited for use in positioning PCBs for drilling. As a result, the preferred embodiment of the present invention is described in that context. It should be recognized, however, that such description is not intended as a limitation on the use or applicability of the present invention, but is instead provided merely to enable a full and complete description of a specific embodiment. Other implementations may be recognized by those skilled in the art upon review of this disclosure. 
     FIG. 1 is a top view of a tooling plate  100  that is used to hold a PCB for machine drilling. Tooling plate  100 , preferably fabricated from a light metal such as aluminum, has a work area  110  onto which the PCB is placed. A registration bar  120  is located in a channel  115  of the tooling plate such that the top surface of registration bar  120  is coplanar with, or below, work area  110 , Similarly, a registration block  125  and a clamping bar  105  are located in channel  115 , so that the top surfaces of registration block  125  and clamping bar  105  are also coplanar with, or below, work area  110 . Registration block  125  is spaced away from registration bar  120  so that block  125  and registration bar  120  can each be moved independent of the other and thus may be separately calibrated. 
     referring now to FIG. 2, a PCB  300  is illustrated with first registration pin  310  and second registration pin  320  inserted therein. The registration pins are used to align the PCB  300  to tooling plate  100  of a machine tool (now shown). Registration pins  310  and  320  extend below the surface of PCB  300  to engage the channel  115 . the PCB is manually loaded on tooling plate  100  so that registration pins  310  and  320  extend into channel  115  of the tooling plate to permit the PCB to lie flat on the tooling plate  100 . As shown in FIG. 3, illustrating a top view of a portion of the tooling plate  100  from FIG. 1, first registration pin  310  (PCB is not shown) is positioned in place against registration block  125  and registration bar  120  by a clamping cam (not shown). Second registration pin  320  (not shown), also referred to as an anti-rotation pin, is held in place against registration bar  120  by clamping bar  105  (see FIG.  1 ). In this configuration, the PCB is held securely in place for drilling. The spindle (not shown) moves perpendicular to the tooling plate in at least the Z direction to drill holes in the entire tooling plate is moved in the plane to position the board or work piece for drilling 
     Referring to FIG. 1, registration bar  120 , preferably fabricated from stainless steel so as to better withstand changes in temperature, is mounted to tooling plate  100  by a plurality of mounting screws  155 . Registration bar  120  preferably has an elongated straight edge  122  so that the registration pins can be biased against the registration bar at any position along the bar. Edge  122  is aligned to the machine calibration position to align the anti-rotation pin in a registration position known to the machine. Adjustment mechanisms  130  are positioned along the outer edge of registration bar  120  on the side opposite surface  122 . The number of adjustment mechanisms may vaty, but in this specific embodiment preferably there are three such mechanisms  130  that are equidistantly spaced apart along the registration bar  120 . 
     Each adjustment mechanism  130  is mounted such that its upper sluface is co-planar with, or below work area  110 , so that the PCB can be positioned flat on the tooling plate. Refeiring to FIG. 3, adjustment mechanism  130  comprises a molunting block  140  fastened to adjacent channel  115  with fasteners  160 , and an adjustment screw  135 . Fasteners  160  may be rivets, screws, pins or the like. Moumting block  140  is securely attached to tooling plate  100  by the fasteners, and is held rigidly in place. Alternatively, the mounting block may be made integral with the tooling plate. Adjustment screw  135  extends through mounting block  140 , so that the adjustment screw contacts the edge of registration bar  120  to effect the controlled movement of the registration bar, as will be described in more detail below. In this mainuer, registration bar  120  is coupled operatively to adjustment mechanisms  130 . In the illustrated embodiment, there is a recess  130   a  in the tooling plate for receiving the adjustment mechanism  130 . The recess provides sufficient clearance between adjustment mechanism  130  and the sides of the recess  130   a  to permit manipulation of the adjustment screw  135 . 
     Referring to FIG. 1 clamping bar  105 , preferably fabricated from stainless steel, is slidably mounted to tooling plate  100  by mounting screws  157 . Clamping bar  105  is positioned so that its longitudinal axis is parallel to the longitudinal axis of registration bar  120 . Clamping bar  105  is moveable across channel  115 , toward and away from the registration bar. Clamping bar  105  clamps the anti-rotation pin  320  into place as described in more detail below. 
     Referring again to FIG. 3 registration block  125 , preferably fabricated fiom stainless steel, is mounted to tooling plate  100  by at least one mounting screw  175 . In the described embodiment two moumting screws  175  are shown. In the illustrated forming a block embodiment, registration block  125  is formed with a straight edge  127  registration suface for receiving registration pin  310  against the registration block at any position along the straight edge to accommodate registration pins of different diameters without the need to recalibrate the position of registration block  125 . When registered, registration pin  310  is clamped into position against edge  127  and registration bar  120 . Adjustment mechanism  162  is attached to the tooling plate adjacent to registration block  125  and is received in a recess  162   a . Adjustment mechanism  162  is mounted such that it is co-planar with or below work area  110  so that the PCB to be worked can be positioned flat on the tooling plate. Adjustment mechanism  162  comprises a mounting block  165 , a plurality of fasteners  170 , and an adjustment screw  145 . Fasteners  170  may be rivets, screws, pins or the like. Mounting block  165  is securely attached to tooling plate  100  by the fasteners, and thus is held rigidly in place. Alternatively, the mounting block may be made integral with the tooling plate. Adjustment screw  145  extends through mounting block  165 , so that the adjustment screw contacts registration block  125  on a side opposite the straight edge  127  to effect the controlled movement of the registration block, as described in more detail below. In this manner, registration block is coupled operatively to adjustment mechanism  162 . In the illustrated embodiment, there is a gap between registration bar  120  and registration block  125  so that the registration bar and the registration block can move independently. This gap is less than the radius of any registration pin  310 . 
     A cover  150  is secured to the tooling plate by fasteners  180 . Cover  150  is easily removed so that there is access to the registration block cam  200  beneath the surface of the tooling plate. 
     Referring now to FIG. 4 registration pin  310  is positioned adjacent to registration bar  120  and registration block  125 . A registration cam  200  is moved away fiom registration pin  310  to allow it to be manually positioned in the channel adjacent the registration block  125 . A pneumatic or other actuator  210  is coupled to cam  200  through a link  220  shown as a dotted line. The link pivots about a pivot point  225  on actuation of the actuator  220  as shown in FIG.  5  and clamps the registration pin  310  against the registration block  125  and the registration bar  120  as illustrated in FIG. 5 thus holding registration pin  310  into a registration position. A similar actuating mechanism (not shown) known in the art clamps the anti-rotation pin  320  against the registration bar  120  to hold both the registration pin  310  and the anti-rotation pin  320  in a known alignment in registration with the tooling plate. FIGS. 6 and 7 are detailed close-up views of the registration pin cam  200  in the open and in the closed position showing the mamuer of engagement with registration pin  310 . 
     Operation of the registration pin alignment system is as follows. Wien a PCB is loaded onto the drilling machine, the PCB or work piece is registered by using the location of the first registration pin  310  as the starting datum. First registration pin  310  is biased by the clamping cam  200  against registration block  125  and registration bar  120 . The zero registration point is adjusted by moving the registration block and registration bar. Registration bar  120  and registration block  125  can each be moved independently due to the clearance between registration bar  110  and registration block  125 . Movement of the registration block is restricted to one axis (i.e., the Y-axis). Similarly, movement of the registration bar is restricted to an axis that is perpendicular (i.e., the X-axis) to the axis of movement for the registration block. 
     The position of registration block  125  and registration bar  120  is adjusted as follows. Block  115  and bar  120  can be adjusted in any order. Referring again to FIG. 3, registration block  125  is moved by tulning adjustment screw  145 . Adjustment screw  145  extends through mounting block  165  and contacts registration block  125  for the controlled movement of the registration block. Turning adjustment screw  145  in one direction will cause the adjustment screw to move into contact with registration block  125 . Consequently, registration block  125  will move in one direction along the Y-axis. Turning adjustment screw  145  in the other direction will move the adjustment screw away from registration block  125 , thus enabling the registration block to be moved in the opposite direction along the Y-axis as is known in the art. Once the registration bar  120  has been properly positioned, adjustment screws  135  may be moved away from the registration bar  120 . The adjustment screw can be turned in small, controlled movements, so that the registration block can be positioned precisely to sub-micron accuracy. Once registration block  125  is in the correct position for proper registration of the machine drill, then the position of the registration block can be fixed on tooling plate  100  by tirning mounting screws  175  and thus holding the registration block rigidly in place. 
     Registration bar  120  is adjusted in a similar manner. Refeting back to FIG. 1, registration bar  120  is moved by turning adjustment screws  135 . Each adjustment screw  135  extends through mounting block  140  and contacts registration bar  120  for the controlled movement of the registration bar. Turning adjustment screws  135  in one direction will cause the adjustment screws to move into contact with registration bar  120 . Consequently, registration bar  120  will move in one direction along the X-axis. Turning adjustment screws  135  in the other direction will move the adjustment screws away from registration bar  120 , thus enabling the registration bar to be moved in the opposite direction along the X axis as known in the art. Once the registration bar  120  has been properly positioned, adjustment screws  135  may be moved away from the registration bar  120 . The adjustment screws can be turned in small, controlled movements, so that the registration bar can be positioned precisely to sub-micron accuracy. Once registration bar  120  is in the correct position for proper registration of the machine drill, then the position of the registration bar can be fixed on tooling plate  100  by turning mounting screws  155  and thus holding the registration bar rigidly in place. 
     When PCB  300  is located onto tooling plate, registration pins  310  and  320  are mounted into holes in the PCB as illustrated in FIG.  2 . The PCB is placed on the tooling plate so that the registration pins extend into channel  115  of the tooling plate adjacent to the registration bar  120  and registration block  125 . First registration pin  310  is placed against registration block  125  and registration bar  120  so that the pin is in the corner of the right angle formed by the registration block  125  and the registration bar  120 . Second registration pin  320  is placed against registration bar  120 . Trailing registration pin  320  is held in place against registration bar  120  by clamping bar  105 . Lead registration pin  310  is held in place against registration block  125  and registration bar  120  by clamping cam  200 . In this manner, the PCB is held securely in place at a known registration location so that accurate drilling or other machine operations can take place on the PCB. 
     While a specific embodiment of this invention has been described in detail above, those skilled in the art will readly appreciate that many modifications are possible in the specific embodiment, without materially departing from the novel teachings and advantages of this invention. For example, the registration block and registration bar could be made integral. Accordingly, all such modifications are intended to be included within the scope of this invention, as defined in the following claims.