Abstract:
A punch press alignment instrument has upper and lower cylindrical components that are associated for vertical displacement relative to one another. Both components have outer tool holder engaging surfaces which are to be aligned with one another so as to in turn align the tool holders of the punch press when the upper and lower components themselves are in alignment. Alignment elements, e.g., ridges and grooves provided on mating surfaces of the components confronting each other are brought into contact with one another to move the components of the instrument into mutual alignment. An alignment control member, e.g., a screw is preferably provided for progressively bringing the upper and lower components toward one another and an indicator such as a lamp, a dial indicator or an audible indicator is provided for denoting the spacing between the upper and lower components to thereby confirm the alignment of the tool holders.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates to the punch and die art and more particularly to an alignment instrument for a punch press.  
       BACKGROUND OF THE INVENTION  
       [0002]     In many standard punch presses, a punch element is carried on an upper turret in alignment over a die that is mounted on a lower turret. The punch and die are both held in circular tool holders. Before the press can be operated, the tool holders must be placed in vertical alignment with one another so that the punch and die are in turn in alignment during operation. An alignment tool previously used by the assignee of the present invention included upper and lower parts in which the upper part was provided with a pair of laterally spaced apart downwardly extending cylindrical pins that were placed in corresponding cylindrical openings in the lower part of the device to align the tool holders. The device was cumbersome to operate and there was no means of indicating when the upper and lower parts of the device were in alignment. Alignment tolerances were also not as good as are sometimes required. In addition, there was no device for progressively moving the upper and lower parts toward one another or for automatically bringing them into progressively better alignment with one another.  
         [0003]     In view of these and other deficiencies of the prior art, it is one object of the invention to provide an improved alignment instrument that will align a punch and a die in three ways simultaneously; horizontally on perpendicular x an y axes with respect to the base of the punch press as well as automatically rotating the die with respect to the punch about a common vertical axis.  
         [0004]     Another object of the invention is the provision of a device for moving upper and lower components of an alignment instrument apart or toward one another under the control of an operator for bringing them into alignment.  
         [0005]     Yet another object of the invention is the prevision of an indicator that operates automatically to indicate the alignment of two components of the instrument which in turn align a punch holder with a cooperating die holder.  
         [0006]     A still further object of the invention is the provision of an improved punch press alignment instrument having a visual display that will indicate both partial and complete alignment of components.  
         [0007]     These and other more detailed and specific objects of the invention will be apparent in view of the following description and drawings which illustrate by way of example a few of the various ways the invention can be carried out within the scope of the appended claims.  
       SUMMARY OF THE INVENTION  
       [0008]     Briefly, the instrument comprises first and second mating parts or components, preferably cylindrical in shape, that are associated for longitudinal displacement relative to one another. Both parts have outer tool holder engaging portions which are to be aligned with one another to align the tool holders of the punch press when the first and second parts are in alignment. Alignment elements that are provided on mating surfaces of the parts confronting each other are brought into contact with one another to move the first and second parts of the instrument into mutual alignment. An alignment control member, e.g., a screw, is provided for progressively bringing the parts toward one another and an indicator such as a lamp, a dial indicator or an audible indicator is provided for denoting the spacing between the first and second parts to thereby confirm the alignment of the tool holders. In one preferred form of the invention, the alignment instrument includes upper and lower cooperating components that are each cylindrical in shape and connected together for longitudinal displacement relative to one another on a vertical axis as well as for rotation about the vertical axis. The indicator may consist of a dial indicator or one or more colored lights to indicate correct alignment. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]      FIG. 1  is a perspective view of one form of punch press in which the invention can be used.  
         [0010]      FIG. 2  is a perspective view of the alignment instrument with the upper and lower components spaced apart from one another for clarity of illustration.  
         [0011]      FIG. 3  is a vertical sectional view taken on line  3 - 3  of  FIG. 2  with the upper and lower components in contact.  
         [0012]      FIG. 3A  is a greatly enlarged diagrammatic view showing tactile alignment switches on a larger scale.  
         [0013]      FIG. 4  is a side elevational view of  FIG. 2  partly in section.  
         [0014]      FIG. 5  is a perspective view of the invention with the cover removed.  
         [0015]      FIG. 6  is a horizontal sectional view taken on line  6 - 6  of  FIG. 4  on a slightly smaller scale.  
         [0016]      FIG. 7  is a partial perspective view of the punch press turret area showing the positions taken by the upper and lower components of the instrument just prior to aligning the tool holders.  
         [0017]      FIG. 8  shows how an alignment bar is placed in contact with the alignment instrument.  
         [0018]      FIG. 9  is a diagrammatic plan view showing how the instrument is aligned about a vertical axis with respect to the punch press base.  
         [0019]      FIG. 10  is a greatly enlarged side elevational view taken on line  10 - 10  of  FIG. 5 .  
         [0020]      FIG. 11  is a circuit diagram for the indicator.  
         [0021]      FIG. 12  is another form of an alignment indicator. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0022]     The invention can be employed in several different kinds of punch presses one of which is illustrated by way of example in  FIG. 1 . The punch press indicated generally by the numeral  10  includes a fixed base  12  that may be provided with vertically extending fibers  14  only a few of which are shown for supporting workpiece  16  that is securely held by a pair of clamps  18  which are in turn connected to a positioning rail  20  that is moved rapidly during operation to a series of programmed positions along horizontal x and y axes  22  and  24  under the automatic control of a computer (not shown) to punch a series of openings  26  in the workpiece  16  or otherwise form the workpiece each time the workpiece is brought into the proper position between a punch  28  and cooperating die  30 . The punches  28  are distributed circumferentially on a circular punch turret  32  and the dies  30  in turn are each supported on a lower turret  34  in alignment below one of the punches. During operation, the turrets  32  and  34  are rotated together under control of the machine-operating computer to place the pre-selected punch and die sets sequentially in an operating position  36  where the punching operation is preformed to produce a pre-selected pattern of openings  26  in the workpiece  16 . The punch press  10  as described hereinabove is of any suitable commercial available type and the invention can, of course, be used with any of a variety of punch presses, the construction and operation of which is well known to those skilled in the art.  
         [0023]     As best shown in  FIG. 7 , punches  28  are held in a series of circumferentially arranged annular punch holders  28   a  and the dies are held in annular circumferentially arranged die holders  30   a , each of which can be secured to its supporting turret once aligned with one another by means of fasteners in this case cap screws  40 . To place upper and lower cooperating pairs of tool holders  28   a  and  30   a  in alignment with one another, the alignment instrument  42  of the present invention is set in the tool holders  28   a ,  30   a  and aligned, as will be described below, so as to thereby place each punch and die set into alignment with one another. The cap screws  40  can then be tighten to maintain the alignment once the alignment instrument  42  has been removed.  
         [0024]     The alignment instrument will now be described with references to  FIGS. 2-5 . The alignment instrument  42  includes an upper component  44  and a lower component  46  each generally cylindrical in shape and having outer cylindrical alignment surfaces  48  and  50  respectively which fit within the tool holders  28   a  and  30   a  respectively during use. The upper component or part  44  includes a central chamber  52  within which is provided a battery pack  54 , a control circuit  56  ( FIG. 3 ) described more fully in connection with  FIG. 11  and an indicator light  58  which projects through an opening in a removable sheet metal cover  60 . The upper and lower components  44 ,  46  are provided with complementary mating surfaces comprising a pair of upwardly projecting downwardly opening slots  43  and  45  in the upper component  44  and two pair, i.e., four vertically disposed upwardly extending complementary teeth  43   a  and  45   a  that project upwardly from the top surface of the lower component  46   a  into the mating slots  43  and  45 . It can be seen that the teeth  43   a  and  45   a  are in nonparallel (in this case perpendicular) relationship as are the cooperating slots  43  and  45 . The teeth  43   a  and  45   a  are provided only on the outer annular portion  46   a  of the lower component  46  and the slots are similarly positioned to extend upwardly from the lower surface of the upper component  44  of the instrument.  
         [0025]     Extending downwardly through a bottom surface  62  component of  44  are a plurality (typically three) alignment indicators comprising contact sensing switches, two of which,  64  and  66 , can be seen in  FIG. 3 .  FIG. 3   a  shows how actuator buttons  68 ,  71  and  73  of all the switches  64 ,  65  and  66  are placed at different elevations so as to be actuated sequentially by contact with a flat horizontally disposed upper switch contact surface  70  of the lower component  46 . Because the switch contact buttons  68 ,  71  and  73  are at different elevations, as the upper component  44  is lowered, switch  66  will be actuated first, then switch  65  and finally switch  64  will be actuated. To establish the correct zero point, each of the switches  64 - 66  is threaded into the upper component  44 . The switch  64  is then threaded up or down until it turns on exactly when the upper and lower components  44  and  46  are aligned and in contact with one another. The other two switches  65  and  66  are then set to project different distances below switch  64  to indicate when the components are coming close to alignment.  
         [0026]     The upper and lower components  44  and  46  of the instrument  42  are brought toward one another during operation by means of a control member consisting of a screw  72  having an operating knob  74  that is turned manually and a threaded section  76  at its lower end that is screw threaded into a vertical threaded bore  78  in the lower component  46 . The screw  72  is provided with a shoulder  80  that bears against the bottom wall of the chamber  52 . A snap ring  82  on screw  72  keeps the screw within a bored opening  84  ( FIG. 3 ) at the center of the upper component  44 . The lower component  46  consists of an annular outer portion  46   a  and a central disc  46   b  which is secured to  46   a  by fasteners such as screws  90  ( FIG. 3 ). Optionally provided on the lower component  46  are plurality, in this case three spaced apart spring loaded plungers  92  each having an upwardly projecting downwardly compressible spring loaded plunger element  94  that exerts an upward force on part  44  as parts  44  and  46  are brought together. The spring loaded plunger  94  functions as lifting units to raise the upper component  44  from the lower component  46 . The travel of the plungers is great enough to lift the upper component  44  a sufficient distance to compensate for rotational inaccuracies of the upper turret with respect to the lower turret when the turrets are rotated into the loading position, i.e., when not in the active position shown at  36  in  FIG. 1 . Alternatively, a spring can be placed between clip  82  and component  44 .  
         [0027]     Component  44  includes a vertical longitudinally extending outwardly opening alignment slot  49  on its outer surface  48  that during operation is engaged on a positioning lug  29  which extends centrally from an inside surface of the punch holder  28   a . Similarly, the lower component  46  is provided with a vertical outwardly opening slot  51  which is engaged during use over a centrally extending alignment lug  31  that projects centrally from die holder  38 . The lug  29  thus provides a zero reference point to establish the correct rotational position of the punch holder  28   a . The positions of the upper and lower components  44  and  46  just prior to alignment are indicated by dashed lines in  FIG. 7 . The upper component  44  is also provided with a horizontally extending outwardly opening slot  53  with a vertically disposed inner surface  53   a  ( FIG. 8 ).  
         [0028]     Refer now to  FIGS. 8 and 9 . When the upper portion  44  the instrument is to be aligned with the positioning rail  20 , an alignment bar  100  is placed manually in the slot  53  and is held firmly against the inner surface  53   a . The bar  100  is then aligned with positioning rail  20 , e.g., by making measurements at (A) and (B) until (A) and (B) are equal. The dimensions (A) and (B) can be measured using an ordinary linear scale, a dial indicator or by means of a suitable optical distance measuring system. Once (A) and (B) are measured and found to be equal, the punch holder  28   a  is properly aligned about a vertical axis  6 . The caps screws  40  holding the upper tool holders  28   a  in place can then be tightened to securely lock the upper component  44  of the instrument in place on the upper turret  32 . With the lower caps screws loose, the lower component  46  of the instrument is placed in the die holder  30   a  with the lug  31  in slot  51 . The alignment control screw  72  is then turned downwardly by hand using the knob  74  so that the threads  76  at its lower end draw the upper component  44  downwardly into contact with the lower component  46 .  
         [0029]     Refer now to  FIG. 10  which shows how each of the teeth  43   a ,  45   a  are tapered by providing tapered side walls  110  that converge toward one another proceeding toward its upper surface  112  so that each of the teeth is wider at its base. It was found suitable to taper each of the sidewalls at an angle S which can be about 15° to the vertical as shown in  FIG. 10 .  
         [0030]     It will be noted that when the upper and lower components  44  and  46  approach one another as shown in  FIG. 2  and  10 , the tapered walls of the teeth  45   a  as well as teeth  43   a  will gradually be brought into contact with the slots  43  and  45 . Since the teeth  43   a  are not aligned with teeth  45   a  (in this case are at right angles thereto) the upper and lower components will be brought into coaxial alignment on horizontal x and y axes simultaneously. At the same time, the engagement between the sidewalls  110  of the teeth with the corresponding inner walls of the slots  43  and  45  will rotate the lower component  46  slightly bringing it into perfect rotational alignment with the upper component  44  about a common vertical axis that is orthogonal to the x and y axes. Thus, alignment is achieved between the upper and lower components  44  and  46  simultaneously on two mutually perpendicular horizontal axes while angular alignment is achieved about a common vertical axis.  
         [0031]     The instrument can be manufactured in various ways, but it has been found highly advantageous first to machine the sidewalls  48  and  50  of the instrument  42  including both the upper component  44  and the lower component  46  while part of a single cylinder of steel and to grind the outer surfaces  48  and  50  concentric with one another to form the tool holder engaging surfaces and thereafter sever the upper component  44  from the lower component  46  by electrical wire discharged machining (EDM). Alternatively, the components  44  and  46  can be securely reconnected after being severed and then finished on their outer surfaces. In EDM machining, a high voltage electrical potential is established between the part being machine and an electrical discharge wire that is held under tension. To simplify machining, the teeth and the slots are each positioned somewhat laterally of center as shown in  FIGS. 2 and 6 . For example, in separating the parts  44 ,  46  in  FIG. 10  an electrical discharge wire  115  shown in end view is first moved laterally at  116 , then upwardly at a 15° angle as shown at  117 , laterally across the top of the teeth  45   a  toward the right, downwardly on a 15° incline, horizontally at  120  until the parts are separated. The surfaces of the teeth and slots, i.e., ridges and grooves, can be left unpolished or if desired can be polished by hand with an abrasive surface such as an Arkansas stone. EDM has been found highly effective in maintaining alignment between the upper  44  and lower  46  components of the instrument  42 . The concentric machining of the surfaces  48  and  50  while the instrument is in one piece or subsequent to splitting it will assure concentricity and hence proper alignment of the tool holders after the components  44  and  46  have been separated. Other precise machining methods can be used in place of EDM if desired.  
         [0032]     Refer now to  FIG. 11  which shows the circuit diagram for the indicator light  58 . In this case the indicator light  58  is a three lead tri-color light emitting diode (LED) having a green diode component (A) and red component (B) which are connected in parallel so that the light or diode module  58  has three leads  120 ,  122  and  124  which are wired across the battery  54  (two AA cells) by conductors  126  and  128 . Wired in series with the diodes are two dropping resisters  130  and  132  that are connected in parallel through the normally closed switch  64  to the battery  54  via conductor  128 . The resistors can be  47 -ohm  1 / 4  watt resistors. Wired between the resistor  136  and the diode (B) is the normally closed switch  65 . In series with the battery  54  is a normally open switch  66 . While any suitable switches can be used, tactile switches such as DB 5 series switches by Omron Corporation of Schaumberg, Ill. can be used. The LED  58  can be a model LTL-30EHJ unit by Light-On Electronics, Inc.  
         [0033]     In operation, as the knob  74  of the control  72  is turned bringing the upper and lower components  44  and  46  closer together, the switch  66  is closed first through engagement with the switching surface  70  which turns on diode (A) to produce a red light. Next, as the upper and lower components  44 ,  46  are brought into even better alignment, the switch  65  is opened thereby turning on the diode (B) so as to produce a yellow light through a combination of (A) and (B). Finally, when the upper and lower components  44  and  46  are in perfect alignment, the switch  64  is opened so as to turn off the current to the diode (A) leaving only (B) a green light which indicates that the components  44  and  46  of the instrument  42  and the tool holders  28   a  and  30   a  which are in contact with them are in alignment with each other. The caps screws  40  that hold the punch holder  28   a  have already been tightened or can now be tightened to lock the punch holder  28   a  in place on the turret  32 . Cap screws  40  that hold the die holder  30   a  can now be tightened to secure the die holder  30   a  in place on the turret  34 . The alignment of the punch and die is now assured. The instrument is then removed from the punch and die holders  28   a ,  30   a . This process is continued until all the cooperating pairs of punch and die holders have been locked in alignment on the turrets  32  and  34 . The punch and die sets can then be placed in the holders with assurance that they are in alignment. The punch press  10  is then operated conventionally.  
         [0034]     While the alignment sensors  54 - 56  in the example given are contact sensing switches, the alignment of tool holders as determined by the spacing between the upper and lower components  44  and  46  can be sensed in other ways, e.g., optically, magnetically, by ultrasonic sensing or even with a feeler gauge to thereby indicate the degree of alignment or misalignment between the upper and lower components  44  and  46 . Alignment can be indicated either visually as already described or audibly, e.g., by means of a sound-producing device to provide a tone or series of beeps.  
         [0035]     Refer now to  FIG. 12  which illustrates another embodiment of the invention that employs a different kind of alignment indicator. In this case, the knob  74  at the top of the control  72  has rigidly connected to its lower edge a thin metal flange  74   a  with pointer  74   b . The top of the cover  60  which in this case is rigidly fastened to the top of the upper component  44  by screws or other fasteners  61  is provided with a circular scale  63  which comprises printed indicia or other markings to indicate the spacing between the upper and lower components of the instrument  42 . When the pointer  74   b  reaches zero on the scale the upper and lower components are aligned. The knob  74  includes a force-limiting clutch like that commonly used in a micrometer which is adapted to release upon reaching a predetermined torque limit to reduce and preferably eliminate distortion of the apparatus, e.g., the screw  72  or switches  64 - 66  or the surface  70 .  
         [0036]     The invention has proved to be highly successful by providing a dimensional precision that has been improved to the point where alignment devices previously available are not good enough to match tolerances that can be achieved with the invention.  
         [0037]     In addition, the present invention provides inherent precision while at the same time having a low manufacturing cost, ease of obtaining accurate alignment of undisputed quality and simplicity of operation.  
         [0038]     In one typical application, the instrument  42  is used in the following way. First, working in the loading area  37  ( FIG. 1 ), the cap screws  40  of a cooperating pair of punches including punch holder  28   a  and die holder  30   a  are tightened just barely snug. Second, the lower component  46  is installed into the die holder  30   a . The lower cap screws  40  are then tightened securely. Third, the upper component  44  is slid into the upper holder  28   a . The alignment control  72  is then rotated about five turns but without clamping parts  44  and  46  together. The light  58  should not be lit. Next the instrument  42  is rotated into the operating station under the ram at  36  in  FIG. 1 . The turrets  32 ,  34  should not be rotated when  44  and  46  are clamped tightly together.  
         [0039]     The control knob  74  is then tighten snug by hand so that the light  54  moves through red, yellow and stops on green. When the light  58  is glowing green, the alignment bar  100  is placed in the slot  53  and held securely against surface  53   a . The component  44  is then rotated slightly to twist the holders  28   a  and  30   a  until the alignment bar  100  is aligned with the positioning rail  20  as shown in  FIG. 9 , i.e., so that (A) and (B) are equal. A rod or other handle (not shown) can be attached to the component  44  to facilitate rotation. Next, as many of the upper cap screws  40  as can be reached should be tightened to secure the punch holder  28   a  in place on the turret  32 . Alignment of the bar  100  should then be re-checked after which the alignment bar  100  can be removed.  
         [0040]     Next, the knob  74  is loosened about two turns making sure that the light  58  is not lit. The turrets  32  and  34  are then turned to bring the instrument  42  back to the loading station  37 . Both upper and lower cap screws  40  are then tightened with a standard hex wrench. Clearances should then be checked again to make sure nothing has moved, but if it has previous steps should be repeated. If nothing has moved, all of the cap screws  40  should be torqued to a desired setting and held with an anti-rotational compound or by other means. Alignment should then be re-checked to confirm that nothing has moved. If it has, previous steps should again be repeated to obtain the proper alignment. Alignment can be confirmed by making sure the LED turns green when the knob  74  is tightened. The station being aligned is now in alignment and the instrument  42  can be removed.  
         [0041]     Many variations in the present invention within the scope of the appended claims will be apparent to those skilled in the art once the principles described herein are read and understood.