Gear rolling equipment
BRIEF SUMMARY OF THE INVENTION 
     The present invention relates to finish forming bevel gears, and particularly hypoid gears, by rolling them in mesh with a tool in the form of a bevel pinion. The tool is mounted on a rotary tool spindle and the work gear is mounted on a rotary work spindle. Means are provided for positively driving one of said spindles, preferably the tool spindle, in rotation and the meshed engagement between the gear and tool results in corresponding rotation of the work spindle. 
     During the rolling operation forces are applied to establish relatively heavy rolling pressure contact between the teeth of the gear and tool. 
     One of the problems in a machine as described in the foregoing is to provide automatic loading equipment in which unfinished work pieces may simply be fed into the machine and will advance continuously therethrough, entering into proper mesh with the tool gears, and finally being advanced from the machine on suitably formed exit rails. This loading equipment must provide for movement of the successive work gears into full mesh with the tool without the possibility of engagement between the crests of the teeth of the gear and tool and consequent failure to mesh. 
     Automatic meshing engagement during the automatic loading of the machine is accomplished by mounting the tool on a tool spindle in a fixed position thereon, and between gear rolling operations fixing the location of the tool spindle so that its teeth occupy precisely predetermined angular positions. Conveniently, this is accomplished by shot bolt means. 
     At the same time, after a finished work gear is removed from the work spindle, the work spindle is positively maintained in a random position as for example by the application of suitable brake means to the spindle in whatever position it happens to occupy at the conclusion of a gear rolling cycle. 
     Means are provided on the work spindle for fixing the work gear thereon against rotation so that the work gear is rotatable only with the work spindle after the brake means has been released. 
     In order to insure that the teeth of each work gear as it is located on the work spindle are in proper position to enter into full mesh with the teeth of the tool, means are provided for positioning each work gear as it advances in a fixed position in which its teeth are precisely mounted in the required angular position. This in general is accomplished by advancing each work gear along rail means into engagement with a series of resiliently mounted fingers which will enter into engagement in the tooth spaces of the work gear. Conveniently, these fingers may be mounted on a leaf spring so that if they fail to engage in the tooth spaces of the work gear, the fingers will be displaced against the spring until such time as they drop into the tooth spaces. 
     The individual work gears are advanced along the rails by a feeding abutment including the roller which engages the internal diameter of the gears in an off-center position located toward the side of the gears which will engage the locating fingers. This insures that the gear is biased toward the fingers as it advances. In the final position each gear encounters a locating abutment which determines its position in space while its angular position is determined by the tooth locating fingers as previously described. 
     At this time to provide final assurance that the gear is properly located, a ball type locator mounted on a pivoted lever is moved downwardly into engagement with a tooth space. If for any reason the ball point of the locator fails to enter a tooth space, suitable limit switch means controlled by position of the pivoted arm insures that further automatic operation of the machine is prevented until the difficulty is cured. 
     Having thus located a work gear in a precisely predetermined position in space and with the precisely predetermined angular position, the gear is now conveyed into axial alignment with the work spindle. Conveniently, the work spindle may include an expanding arbor which when contracted is adapted to receive the work gear upon relative axial movement between the spindle and the gear. 
     In the preferred embodiment of the invention each work gear after having been properly located as above described, is engaged between clamping jaws, which jaws are then elevated and transferred into position to align the gears with the work arbor. Preferably, the work gears are advanced with their axes vertical and the work spindle axis is so vertical. After the jaws advance the work gear into alignment with the spindle, the jaws lower the gear onto the spindle and hold it against rotation until the arbor is expanded to fix the gear thereon against rotation. 
     Thereafter, the jaws are retracted and the work spindle and tool spindle relatively moved to bring about meshing engagement between the work and tool. In the preferred form of the invention the tool spindle is maintained in a fixed horizontal position and the work spindle is elevated to bring the gear into appropriate mesh with the tool. After the tool and gear have been properly meshed, the shot bolt locator means is de-activated to release the tool spindle and the brake is deactivated to release the work spindle for rotation. One of the spindles, preferably the tool spindle, thereafter is driven in rotation at substantial speeds and the meshed engagement between the tool and gear bring about corresponding rotation of the work spindle. 
     Preferably, the work spindle is carried by a vertically movable slide which in turn is moved vertically by one or more hydraulic cylinders capable of establishing the relatively great rolling pressure required to finish the toothed surfaces of the work gears by a roll finishing operation. 
     After the rolling operation is completed the work spindle moved downwardly bringing the work gear out of mesh with the tool and after this meshing engagement is terminated the location of the tool spindle is again fixed by activation of the shot bolt means and the work spindle is fixed against rotation in a random position by activation of the brake. 
     Gear receiving means are provided movable into position at opposite sides of the work spindle while the work gear is being rolled which are adapted to receive the finished gear as it moves downwardly with the work spindle. At this time the expanding arbor is contracted so that as the arbor continues its downward movement the finished gear is stripped from the arbor and deposited on the gear receiving means. 
     The gear receiving means reciprocates and following deposit of a gear thereon it moves laterally from the axis of the work spindle to move the finished gear onto discharge rails where it joins other previously finished gears which are advanced in a step-by-step relation by pivoted fingers. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a fragmentary perspective view showing the working station of the machine. 
     FIG. 2 is a diagrammatic representation of the major essential machine components. 
     FIG. 3 is a side elevation of the work loading station. 
     FIG. 4 is a plan view of the structure shown in FIG. 3. 
     FIG. 4A is an enlarged detail view of the work locating mechanism. 
     FIG. 5 is a fragmentary end view of the structure shown in FIG. 3. 
     FIG. 6 is a fragmentary elevational view of the work transfer carriage and slide. 
     FIG. 7 is an end view of the structure shown in FIG. 6. 
     FIG. 8 is an enlarged sectional view of the work clamp mechanism. 
     FIG. 9 is an elevational view of the machine structure at the work spindle. 
     FIG. 10 is a plan view of the structure shown in FIG. 9. 
     FIG. 11 is a fragmentary end view substantially at the line 11--11, FIG. 9. 
    
    
     DETAILED DESCRIPTION 
     Referring first to FIGS. 1 and 2 the machine comprises a preliminary loading station indicated at 10 in FIG. 1 in which a work gear W is located in predetermined spatial relationship and in accurately determined rotational or angularly oriented position. The machine comprises a tool T fixedly mounted on a tool spindle 12 which is maintained in fixed spatial relation. The machine frame indicated generally at 14 comprises a vertically movable knee 16 including a work spindle 17 the upper end of which terminates in an expanding arbor 18. 
     Rails 20 are provided on which a carriage 22 is horizontally slidable. Mounted for vertical movement on the carriage 22 is a slide 24 having opposed clamping jaws, one of which is indicated at 26. 
     Referring now to FIG. 2 the tool T is fixedly mounted on the tool spindle 12 and is adapted to be driven in rotation by a motor 28, preferably a hydraulic motor. Between finishing cycles the tool spindle 12 is maintained in a precisely predetermined angular or rotational position by suitable means such for example as a shot bolt 30 adapted to enter into a recess in the tool spindle 12. This accordingly arrests the tool T in a predetermined angular position. 
     Mounted at the front of the machine is a vertically movable knee 16 in which the work spindle 17 is rotatable. The knee 16 is movable vertically by suitable means such as one or more hydraulic cylinder devices 34. 
     Suitable adjustable abutment means are provided for limiting the upward movement of the knee. Such means are diagrammatically indicated as adjustable abutment screws 35. In practice, four such abutments are provided and in the gear rolling operation these adjustable abutments determine the finish size of the gear. In other words, the upward force applied by the hydraulic piston and cylinder devices 34 will bring work gears G to the same size which is determined by the adjustment of the abutments 35, irrespective of some variation in size prior to rolling. 
     Fixed to the spindle 17 is a disc 36 associated with a friction brake 38 adapted to arrest the spindle 17 in a random position. The random position is any position in which the spindle 17 happens to come to rest between gear rolling cycles. 
     A succession of work gears awaiting roll finishing operations are provided on an inclined chute which is defined by gear supporting rollers 40 down which the gears advance by gravity into a position determined by engagement with an abutment 42 from which point they are advanced to the right as seen in these Figures. 
     A work advancing mechanism is provided comprising a bar 44 connected to a piston and cylinder device 46 for reciprocating the same. To the bar 44 a gear advancing pin 48 is pivoted, as indicated at 50 and includes a counterweight 52 which normally maintains the pin in its erected position against an abutment screw 54. Also connected to the bar 44 is a second gear advancing device comprising a finger 56 pivoted at 58 and including a counterweight 60 normally holding the finger 56 against abutment means indicated at 62. At the end of the finger 56 is a roller 64 engageable with the interior of a gear in an off-center position with respect to the center line 66 along which the gears advance. The off-center position of the roller is best indicated at 64a in FIGS. 4 and 4A where it is seen to engage within the annulus of the gear in the off-center position as illustrated. 
     On forward movement of the bar 44 the roller 56 is prevented from yielding by the abutment 62 but upon movement to the left of the bar 44 the finger 56 rocks to the position in which the roller 64 occupies the position indicated at 64b, thus leaving the gear in its advanced position. 
     When the work advancing mechanism operates to move a gear into finally located position, it advances the gear into engagement with a fixed abutment 68 which determines the spatial position of the gear. The means for determining its angular or rotational orientation is best illustrated in the enlarged fragmentary view of FIG. 4A. As seen in this Figure the gear G has been advanced into engagement with the stop or abutment 68 by the off-center roller 64a. As a result of the location of the roller the gear is not only advanced to the right as seen in the Figure, but is also given a lateral bias as well as forces tending to rotate the gear in a clockwise direction. It will of course be understood that the gear advances along a horizontal track or rails with its axis vertical preparatory to being positioned on an expanding arbor at the upper end of a vertical work spindle. 
     The advancing work gear is advanced along a side rail 70 to which is attached one end of a leaf spring 72 carrying a plurality of adjustable fingers 74, 76 and 78. It will be observed that finger 74 has a shape corresponding to a tooth space of the gear, whereas the fingers 76 and 78 are ball shaped. The fingers extend through openings 80 in the rail 70 in position to be engaged by teeth at the periphery of the gear G. When the gear comes into engagement with the stop abutment 68 it will have been rotated into the correct angular or rotational orientation by the fingers 74, 76 and 78. 
     As a final assurance that the work gear is in prperly oriented position the mechanism illustrated in FIGS. 4A and 5 is provided. Here, it will be seen that there is provided a lever 82 pivoted as indicated at 84 and adapted to be swung about the pivot axis by means of a piston and cylinder device 86. Mounted on the lever 82 is a limit switch 88 adapted to be engaged by a plunger 90 having a ball tip 92 adapted to enter into the space between teeth of the gear G if the gear is precisely oriented in predetermined angular position. If the ball point 92 happens to engage on the crest of the tooth or fails to enter fully into a tooth space, the limit switch 88 is connected to terminate further automatic operation of the machine. 
     Referring now to FIGS. 6, 7 and 8 there is illustrated the mechanism for gripping the gear in its predetermined angular position and moving it into alignment with the work spindle of the machine. 
     In FIG. 6 the vertically movable knee 16 and work spindle 17 of the machine are illustrated and the spindle at its upper end is provided with an abutment surface 94 and the expanding arbor 18. Separated posts 98 and 100 are provided which at their upper ends carry the rails 20 along which the carriage assembly 22 is movable to the right and left as seen in FIG. 6. The carriage has an upwardly extending bracket 106 carrying limit switches 108 and 110 actuated by abutments 112 on a vertically movable rod 114. Vertically movable on the carriage 22 is a slide 24 carrying clamping jaws 118 at its lower end. The bracket 106 carries a piston and cylinder device 120 to which the slide 24 is connected and the carriage 22 is connected to a piston and cylinder device 122 adapted to move the carriage 22 from the full line position illustrated in FIG. 6 to the right, to a position in which it actuates a limit switch 124. The right hand position of the carriage 22 moves the work gear G to the position indicated in dotted lines at Ga, after which downward movement of the slide 24 moves the gear downwardly to the position Gb in which it abuts the surface 94 and receives the expanding arbor 18 within the central opening therein. 
     Referring now particularly to FIG. 8 there is illustrated the mechanism for actuating the clamping jaws 118. The jaws 118 are each secured to rods 126 the inner ends of which confront each other and are provided with recesses 128 receiving the ends of a compression spring 130 normally urging the jaws away from each other into gear releasing position. Rods 126 are longitudinally slidable in a bore provided in a head 132 at the lower end of the slide 116. A cylinder 134 is provided in which a piston 136 is vertically movable. The rods 126 at their inner ends ar provided with upstanding ears 138 having inclined camming surfaces 140. The lower end of the piston 136 has a recess 142 having correspondingly inclined surfaces engageable with the surfaces 140. When pressure fluid is admitted above the piston 136 the piston is moved downwardly and cams the rods 126 inwardly to clamp the jaws 118 against the periphery of the work gear G. A piston and cylinder device 144 includes a cam (not shown) which retains the jaws clamped during transfer. 
     As best illustrated in FIG. 6 the jaws 118 are located to have a line of action extending diagonally with respect to the center line of advance of the gears so as to avoid interference with the remaining machine structure. 
     After a work gear has been deposited on the expanding arbor 18 of the work spindle 17, the arbor is expanded so that the work gear is securely retained thereon against rotation. At this time the friction brake prevents rotation of the work spindle and accordingly, the work gear maintains its precise required rotational orientation with respect to the tool or die, which of course also remains in fixed position at this time as a result of actuation of the shot bolt. 
     At this time the knee 16 is elevated and the teeth of the tool T and gear G enter into mesh. As soon as this has been accomplished the shot bolt and brake are de-activated so that both work and tool spindles are rotatable and the motor 28 is activated to initiate power rotation of the tool spindle. At the same time continuous pressure is applied to the knee 16 to raise it until further advance is arrested by engagement of the adjustable abutments 35 previously referred to. 
     This completes the rolling operation and thereafter the knee is lowered. 
     Referring now to FIGS. 9-11 there is illustrated the mechanism which strips the finished gear from the expanding arbor and advances it to a discharge chute for step-by-step further advance. 
     The finished work gear G is illustrated in FIG. 9 as supported on the surface 94 of the work spindle 17 and upon downward movement of the knee 16 the gear G will be engaged on support surfaces 150 of a pair of nest members 152 having abutment surfaces 154 engageable with surfaces on the work gear G to the left of its center line designated at 156 in the Figure. Nest members 152 are connected to a transverse bar 158 which in turn is connected to a piston and cylinder device 160 by a bracket 162. It will be observed that the nest members 152 are spaced apart to extend at opposite sides of the reduced portion 164 at the upper end of the work spindle and are movable by the piston and cylinder device 160 from the positions illustrated in FIG. 10 to the right to a position in which they permit downward movement of an unfinished gear onto the expanding arbor 18 when the knee 16 is in its lowermost position. 
     Discharge movement of the finished gears as seen in FIGS. 9 and 10 is to the right, and for this purpose there is provided a trackway or chute indicated generally at 165, as best illustrated in FIG. 11, comprising spaced rollers 166 and vertically extending guard rails or flanges 168. 
     With the parts in the position illustrated in FIG. 9, downward movement of the knee 16 will cause the finished gear G to be deposited on the support surfaces 150 and to have trailing surfaces thereof engaged by the abutment surfaces 154 on nest members 152. At this time of course the expanding arbor 18 is contracted so that downward movement of the knee 16 strips the finished gear G from the expanding arbor and leaves it supported on the nest members 152. 
     At this time the piston and cylinder device 160 is actuated moving the nest members 152 to the right to displace the gear from its position overlying the work spindle 17 preparatory to the placement of a following work gear thereon. The finished gear is advanced onto the beginning of the trackway or discharge chute indicated generally at 165. In order to prevent retrograde movement of a finished gear after it has been removed from alignment with the work spindle, a stop 170 is provided having an inclined upper surface 172 and a stop shoulder 174 engageable with the trailing bottom corner of a work gear. The finished gear thus occupies the position designated in FIG. 9 as Gd, at which time it is prepared for further advance to the right by reciprocation of longitudinally extending bars 176 between which are pivoted feed dogs or fingers 178, the pivot means being indicated at 180. The pivoted dogs are provided with a counterweight 182 normally maintainng the dogs or fingers 178 erect, in which position they are maintained against counterclockwise rotation by an abutment 184. The dogs 178 extend upwardly within the annulus of the gears G and are thus effective to move them to the right by an amount equal to the stroke of the bars 176, which are connected to the piston and cylinder device 160 for accomplishing step-by-step advance of the finished gears. 
     From the foregoing it will be observed that finished gears are removed from the working zone by downward movement of the knee with the expanding arbor in contracted position so that the finished gears are deposited on the transfer means which includes the nest members 152. As soon as the finished gears are separated from the expanding arbor the nest members are shifted to the right, transferring the finished gears to the entry end of the discharge chute 165 in which position they are retained by engagement with the abutment shoulder 174 as the transfer device including the laterally spaced nest members 152 are returned to position at opposite sides of the reduced portion 164 of the work spindle. Reciprocation of the bars 176 causes a step-by-step advance of physically separated gears as a result of engagement of the feed dogs 178. On movement to the left of the bars 176 the dogs 178 pivot clockwise to clearance position and are moved rearwardly for engagement with the next successive finished gear. 
     It will be observed from the foregoing that essentially the machine comprises means for effecting automatic loading including meshing between a work gear and a gear-like tool in which the tool is maintained against rotation in a precisely predetermined position of angular orientation, while the work spindle is retained against rotation in a purely random position. A work gear is advanced to a preliminary loading position and its rotational or angular orientation is precisely predetermined so that as long as this angular position is maintained, it is capable of moving directly into mesh with the tool or die without interference between the teeth thereof. At this time the work gear is transported without disturbing its rotational position into alignment with the axis of the work spindle and is then engaged upon the work spindle against rotation while the work spindle is maintained in its random rotational position. Thereafter, relative movement between the work spindle and tool spindle in a direction parallel to one of such spindles causes meshing engagement between the gear and tool. After this meshing engagement has been brought about the two spindles are released for rotation and one of them is positively driven in rotation while forces are applied tending to produce relative motion between the spindles in a direction which will establish an effective rolling pressure between the surfaces of the teeth of the gear and tool. This rolling pressure is sufficient to displace material at the teeth of the gear and is continued until the relative motion is terminated by engagement of rigid abutments, thus insuring roll finishing of the gears to identical size even though minor variations may exist prior to rolling. 
     Referring to FIG. 2, it will be observed that the directions in which the axes of tool spindle 12 and the work spindle 17 extend are fixed in space. Thus, tool spindle 12 is horizontal at all times and in FIG. 2 extends parallel to the plane of the Figure. Similarly, work spindle 17 is vertical at all times and in FIG. 2 extends parallel to the plane of the drawing. Since the gearing being rolled is hypoid, the axes of the gear and tool are laterally offset in the manner of operating hypoid gearing. The work gear G and its spindle 17 are movable vertically to mesh the gear and tool and to apply rolling pressure, but this movement is along the axis of work spindle 17 and hence does not disturb its orientation in space. 
     In the foregoing reference is made generally to bevel gearing and it is to be understood that this includes hypoid gearing, for which the rolling operation is primarily intended. In the hypoid rolling the pinion element, whether the tool or gear, is located so that its axis is offset laterally from the axis of the gear member. 
     The rolling operation is carried out so that the complete finish rolling of a gear including the loading and unloading is accomplished in a brief interval as for example ten to twenty seconds. The operation is fully automatic and it is necessary only to see that the inclined loading chute is provided with a supply of unfinished gears, and to remove or provide means for receiving the finished gears from the discharge end of the discharge chute 165. 
     Reference is made herein to positioning or maintaining the work and/or tool gears in alignment. This is understood to mean position the gear members as illustrated herein with their axes perpendicular and so positioned that by relative rectilinear movement without rotation they move directly into mesh without tooth interference. Obviously, the relative approach might equally well be arcuate, as by swinging the work gear into mesh on an arm pivoted on a fixed axis. Similarly, if the gears are cylindrical, their axes will be parallel to each other. 
     Reference is made herein to a work spindle and a tool spindle. The term &#34;spindle&#34; is to be understood to have its usual meaning in the machine tool industry, namely, a rotatable member having an axis of rotation on which a tool or workpiece is mounted.