Abstract:
A fully automatic machine tool for simultaneously broaching parallel slots on a plurality of workpieces mounted on a rotatable table in which the table is indexed between a plurality of broaching operations to revolve the workpieces and hence to effect rotation of the workpieces about their own axes with respect to the path of broaching tools.

Description:
BRIEF SUMMARY OF THE INVENTION 
     The present invention relates to a machine tool for performing an operation on a plurality of like workpieces simultaneously. The machine tool has automatic loading and unloading equipment incorporated therein. 
     The embodiment of the invention chosen for illustration herein is a broaching machine, and more particularly a vertical broaching machine in which the broaching operation is of the type known in the art as an internal pull-down broaching operation. 
     As illustrated the workpiece to be broached is an annular body, and the broaching operation is to broach the interior cylindrical surface thereof. As the description proceeds, it will be apparent that the operation could be other than broaching, as for example grinding, turning, or the like. Moreover, where the operation is broaching, the surface to be broached may be internal or external, and the surface may be non-circular, as for example, a toothed surface. 
     BACKGROUND OF THE INVENTION 
     Machine tools of all sorts are today equipped with devices for making the operation fully automatic, and in this connection automatic loading and unloading equipment is provided as an attachment or tooling, or may be incorporated in the machine tool. 
     It is also known to provide machine tools capable of performing like operations on a plurality of workpieces, and more specifically broaching machines for simultaneously broaching a plurality of like parts are known, and are equipped with automatic loaders and unloaders. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, a machine tool, such for example as the six-station pull-down broaching machine disclosed in detail herein, is provided with a plurality of work stations equipped to perform a like number of simultaneous machine operations on a like number of identical workpieces. The work stations are disposed in a regular array, as for example uniformly spaced in a straight line. The machine tool is fully automatic in operation, and a multiplicity of workpieces are advanced in an inchute. Conveniently the workpieces may have an external cylindrical surface so that they may roll down an inclined inchute until the leading workpiece is engaged with a stop, and the following workpieces form a solid array in the chute. 
     The spacing between the work stations will normally be much greater than the spacing of adjacent workpieces, so that non-adjacent workpieces, as for example, every fifth or sixth workpiece is approximately in line with a work station. Means are accordingly provided at the inchute to displace a non-adjacent plurality of workpieces from the solid array in the inclined inchute, and the gaps in the array are filled as the remaining workpieces roll down in the chute. 
     In the machine tool illustrated herein, the workpieces are annular and are to have the central hole broached. It is therefore necessary to turn the individual workpieces 90° to properly present them to a series of vertical, pull-down broaches. 
     Furthermore, the machine tool will normally provide the plurality of work stations at an invariable spacing, and it will usually occur that the workpieces, as displaced from the solid array in the inchute, will not register precisely with the corresponding work stations. Means are provided for receiving the workpieces at the spacing dictated by their dimensions, and advancing them simultaneously into sufficiently precise registration with the broaches to provide for initial insertion of the broaches through the workpieces into engagement with an assembly of broach pullers. 
     The machine tool is designed for maximum production and unloading or ejection means is provided which is effective to simultaneously eject all finished workpieces and to again turn them through 90° so that they may roll down an inclined outchute. This comprises individual camming means associated with each workpiece which are all simultaneously actuated to displace the finished workpieces into a turnover device which deposits them simultaneously in the inclined outchute. 
     The camming means comprises a pair of blocks in alignment with and at opposite sides of each of the workpieces. At least one, and preferably both of the blocks has a camming surface thereon. Corresponding blocks are fixed, and the remaining blocks interconnected for simultaneous movement which displaces the finished workpieces from working position into engagement with the adjacent stationary block and then cams them into the turn-over device which deposits them in the inclined outchute. Accordingly, ejection of all finished workpieces requires only a short travel of the means which interconnects all of the movable blocks. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a fragmentary perspective view of the machine tool. 
     FIG. 2 is a front elevational view of the machine tool. 
     FIG. 3 is a plan view of the machine. 
     FIG. 3A is a detail view of camming ejection blocks. 
     FIG. 4 is a vertical section on the line 4--4, FIG. 3. 
     FIG. 5 is an enlarged sectional view on the line 5--5, FIG. 2. 
     FIG. 6 is a view in the direction of arrow 6, FIG. 2. 
     FIG. 7 is a fragmentary section on the line 7--7, FIG. 3. 
     FIGS. 8-11 are sections on the lines 8--8, 9--9, 10--10 and 11--11, FIG. 7. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 is a fragmentary perspective view of the broaching machine and in this view the inclined inchute is indicated at 10 and is associated with a corresponding pusher bar 12 provided with an assembly of adjustable push rods which move non-consecutive workpieces from the inchute through inclined guide tubes 14 and deposit them on a horizontal support plate along which they are advanced by a multiplicity of pushers into position registering with a like plurality of vertical pull-down broaches. 
     Details of this mechanism are seen in the remaining figures. 
     The present invention relates to a machine tool and in many of its aspects it may relate to different types of machine tools. However the invention is illustrated and described in connection with a machine for broaching cylindrical holes in annular workpieces to a predetermined cylindrical configuration. 
     The inchute 10 which comprises a base plate 16 and side plates 18 is inclined to permit a multiplicity of workpieces W to be received in the chute and to roll downwardly so that the foremost workpiece engages a stop plate 20, the remaining workpieces forming with the foremost workpiece a solid array. 
     It will be understood that it is important to provide the broaching machine with a plurality of stations, each of which has associated therewith a vertical pull-down broach adapted to be drawn through the opening in the aforesaid workpiece W. After each broach has been drawn completely through the workpiece, means are provided for expelling the completed workpieces from the machine and thereafter broach retrievers forming a part of the broaching machine move downwardly and engage the upper ends of the broaches and draw them to the initial position, leaving clear a space into which the following workpieces are advanced for the next broaching operation. The succeeding broaching operation of course involves downward movement of the gang of broaches carried by a retriever support bar, to insert the lower ends of the broaches through the workpieces and into engagement with connections to a puller bar adapted to be moved downwardly by suitable means, such for example as a hydraulic piston and cylinder device. 
     The apparatus has been designed for the specific purpose of increasing the production rate of the machine and accordingly automatic means are provided which ensures rapid infeed and outfeed of the workpieces with a minimum of time consumed by all functions of the machine except for the actual broaching operation. 
     The workpieces may be supplied to the inclined inchute 10 by any suitable mechanism and the supply of workpieces is monitored by a switch 22 which has a flexible actuator 24 adapted to being engaged by successive workpieces as they are supplied to the machine. This switch, details of which form no part of the present invention, incorporates a brief time delay mechanism so that operation of the switch by passage of a succession of workpieces passing beneath the actuator 24 will not terminate operation of the machine. 
     In order that the present machine shall be capable of the operation on a variety of differently dimensioned workpieces, it is designed such that non-consecutive workpieces are projected from the inclined inchute 10 into curved turnover tubes 14 best seen in FIG. 4. For example, if the individual broach stations on the machine have a spacing 41/2 inches and if the individual workpieces have an outside diameter of 11/2 inches, it will be appreciated that every third workpiece in the solid array of workpieces in the inchute 10 is approximately aligned with an individual broach station. However in order to accommodate workpieces which in a solid array have spacings so that not all of the workpieces are aligned with an individual broaching station, means are provided for advancing the workpieces so that each is in substantially exact alignment with an associated broaching station. 
     The individual turnover tubes 14 include a 90° arcuately curved portion and are formed to have a bottom wall 26 and side walls 28 forming a U-shaped tube adapted to receive a workpiece in suitably interfitting relationship so that the workpiece as it is moved through the tube, is turned over so that its axis extends vertically as it is deposited on a base plate 30. The open sides of the support tubes are partially closed by a bent flexible plate 32. 
     Since the support plate 30 is horizontal and the individual workpieces as they are delivered from the inclined inchute are at different heights, the lower end of the turnover tubes 14 are provided with guide tubes 34 of different heights so that all curved turnover tubes 14 for a particular workpiece may be identical. 
     Means are provided for projecting non-consecutive workpieces through openings 36 provided in the side wall 18 of the chute and for this purpose a pusher bar 12 is provided having a plurality of pusher elements 40 adjustably secured thereto in elongated slots 42 as best seen in FIGS. 2 and 4. 
     Referring now to FIG. 5 the pusher bar 12 is connected to an actuator plate 44 as by screws 46 and is adapted to be actuated by a piston and cylinder device 48 which in turn is connected to the actuator plate 44 by the piston 50. Guide bars 52 extend through openings in the inchute 10 so that actuation of the piston and cylinder device 48 advances the pushers 40 so as to project the individual workpieces sufficiently into the curved upper end of the turnover tubes 14 to cause them to move by gravity the remaining distance and thereby deposited on the base plate 30 as best seen in FIG. 4. The corresponding position of plate 44 is shown in dot and dash lines. 
     Referring now more particularly to FIGS. 3 and 4 the workpieces W are received in the individual straight vertical tubes or magazines 34 in side abutting relationship, the lowermost of which is slidably supported on the base plate 30. Spaced above the upper surface of the base plate 30 is a keeper plate 53. A plurality of elongated feed bars 54 are provided slidable in rectilinear guideways provided between the base plate 30 and the keeper plate 53. Feed bars 54 are individually secured to feed bar brackets 56 as by screws 58 and the bracket is connected to a piston 60 extending from a feed cylinder 62 rigidly secured as by screws 64 to the keeper plate 53. 
     The individual feed bars 54 are spaced in conformity with the spacing of the turnover tubes 14 and magazines 34, without reference to the precise spacing between the individual broach stations. This permits adaption of the apparatus to workpieces of different dimensions while maintaining the same spacing between adjacent work stations, as determined primarily by the broaches, broach pullers, retrievers, etc. 
     In order to provide precise alignment of the individual workpieces with the corresponding broaches, the latter being shown at 66 in FIG. 4, the individual feed bars, as best illustrated in FIG. 3 are provided at the front ends thereof with semi-circular recesses 68. These recesses are formed individually in each feed bar so as to be substantially exactly aligned with the corresponding broach station. As a result of this the recesses 68 in the different feed bars are not symmetrically provided at the forward ends of the feed bars. For example, the recess 68 in the second bar from the right in FIG. 3 is adjacent the right side thereof, while recess 68 at the end of right hand bar is centered with respect thereto. In order to provide for proper registration between the workpieces and the broaches, a cam plate 70 is provided having at its lower side individual trackways 72 appropriately and usually differently inclined as appears in FIG. 3 to guide the individual workpiece from its position below the magazine 34 into alignment with the corresponding broach 66. As will be apparent from FIG. 3 the feed bar usually engages the workpiece while the workpiece is not in alignment with the semi-circular recess 68. As the feed bars advance the workpieces move forwardly towards the broaches along the paths determined by the corresponding inclined grooves 72 during this advance, and accordingly are brought into alignment with the associated semi-circular recesses 68. Thereafter the feed bar moves the workpiece forwardly into a located position determined by engagement with a locater pin 74. At this time the workpiece as best illustrated in FIG. 4 is positioned as precisely as required beneath the bottom end of the broach 66. Normally, as is conventional in broaching practice, the workpiece is not positively held but is permitted to be moved by its engagement with the broach into precisely centered relationship therewith. 
     To accomplish this result of course the feed bars are retracted, leaving the workpieces slidable on the support 30 except as such movement is limited by its associated pin. 
     It will be observed that as a particular workpiece is advanced to the right to the position beneath its corresponding broach, as seen in FIG. 4, the superimposed workpiece in the magazine moves downwardly into engagement with the upper surface 76 of the feed bar 54. After the individual workpiece has been suitably engaged by the associated broach, the feed bar 54 is retracted and as soon as its leading end moves to the left of the stack of workpieces, the bottom workpiece drops downwardly onto the top surface of the base plate 30, ready to be advanced by the next actuation of the feed bar. 
     The stroke of the feed bars is determined by a threaded adjustable stop 78 carried by the keeper plate 53 on which the cylinder 62 is mounted. As seen in FIG. 4 the feed bar 54 is shown in its advanced position cooperating with the locater button 74 to locate the workpiece directly beneath the lower end of the broach 66. The adjustable stop 78 is shown in the position it occupies when the feed bars are retracted. 
     The broaching machine includes ganged broach retriever means indicated generally at 79 and similarly ganged broach pullers 80 adapted to engage and interlock with tangs at the lower end of the individual broaches 66. Separate piston and cylinder devices are connected to the ganged broach pullers and retrievers. 
     While the machine illustrated herein is designed for the broaching of small cylindrical holes in annular workpieces, it is desirable to cause the individual broaches to rotate as they are pulled downwardly through the workpieces. The means for accomplishing this comprises a vertical lead bar device indicated generally at 82 which is adapted to rotate all of the individual broach pullers through the medium of suitable gearing interconnecting the pullers. This is for the purpose of eliminating tooth marks parallel to the axis of the workpiece. 
     An important feature of the present invention is the special means designed for ejecting finished workpieces simultaneously from the machine in the shortest possible interval. It will be recalled that the individual workpieces are initially pushed prior to the broaching operation against locater pins 74. This precludes simple ejection of the finished workpiece by movement along the line traversed by the workpiece as it moves from the magazine 34 into alignment with the broach 66. 
     Referring now to FIGS. 3, 4 and 7, each work station has associated therewith ejecting means comprising a stationary unloading block or cam 84 and a movable unloading block or cam 86. Preferably both blocks 84 and 86 have inclined camming surfaces so that as the blocks approach each other the workpiece is engaged between the approaching blocks and is ejected laterally by the cam surface or surfaces thereon. It will of course be apparent that either or both of the blocks 84 or 86 may have the inclined cam surfaces which are indicated at 88 and 90 in FIG. 3A. Stationary blocks 84 are set onto recesses in the base plate 30 and the movable blocks 86 are set into recesses in a tie bar 92 retained in longitudinal slidable relation below transverse straps 94. A piston and cylinder device 96 is connected to the tie bar 92. It will be recalled that the feed bars 54 are retracted to the positions indicated in FIG. 3 after each workpiece has been suitably engaged with the associated broach. When the broaching operation is complete the upper end of the broach is moved downwardly below the workpiece which is then ready for ejection from the machine. However at this time it is still in a position engaging the locater 74. Accordingly when the cylinder 96 is actuated to move the tie bar 92 to the left as seen in FIG. 7 the movable ejection blocks 86 all engage the right hand side of the workpieces as viewed in FIG. 7 and shifts them laterally out of alignment with the locater pin 74 and into engagement with the adjacent surfaces of the stationary ejector block 84. Further motion of the tie bar at this time abruptly cams all of the workpieces laterally of the aligned row which they occupy into a curved turnover discharge chute 98. This of course requires only sufficient movement of the tie bar 92 to close the blocks 84 and 86 onto the finished workpiece and accordingly it may be accomplished with limited travel in a very brief interval. 
     The discharge chute 98 comprises a 90° arcuate portion defined between suitably curved sheets 100 and 102 which are conformed to spacers 104 as best seen in FIGS. 4 and 8-11. The discharge chute 98 as defined between the curved sheets 100 and 102 is open at both its upper and lower ends, except at its lower end it is provided with an inclined rail or rod 106. The inclination of the rail or rod 106 is indicated by the successive sections of FIGS. 8-11 and it will be understood that the finished workpieces simply roll down the rails 106 and free drainage is permitted by virtue of the open end of the discharge chute. 
     As best seen in FIG. 9 the base plate 30 is provided with an annular wear plate 108 against which the individual workpieces rest during the broaching operation and below the wear plate 108 are bushings 110 with the cylindrical openings 112 to receive the lower ends of the broaches and having the end portions of the openings 112 suitable inclined to guide the ends of the broaches as they enter the bushings. 
     Reference was made to a switch 22 including an actuator 24 to monitor entrance of the workpieces into the inclined inchute. 
     It will be understood that the machine is provided with suitable switch means responsive to completion of designated operations which initiate the next successive operation. Since these switches are in general of conventional construction and since the appropriate placement of the switches to monitor the particular operations will be obvious to those familiar with the art, no effort has been made to describe these switches.