US1812660A

US1812660A - Thread cutting means for automatic screw machines

Info

Publication number: US1812660A
Application number: US369068A
Authority: US
Inventors: Judson H Mansfield; Chester F Penrose
Original assignee: Greenlee Brothers and Co
Current assignee: Greenlee Brothers and Co
Priority date: 1929-06-07
Filing date: 1929-06-07
Publication date: 1931-06-30
Anticipated expiration: 1948-06-30

Description

June 3 0, 1931. J. H. MANsFlELD E1- AL THREAD CUTTING MEANS FOR AUTOMATIC SCREW MACHINE Filed June 7, 1929 3 Sheets-Sheet l .MM SISI/V `Fume 30, 1931. ,Sz@

THREAD CUTTINGl MEANS EQR AUTQMATIC SCREW MACHINES J. H. MNSFELD ET AL Filed Junel '7, 1929 s sheets-sheet 2 June 30, 1931. J. H. MANsFlELD ET AL 1,812,660v

THREAD CU`TTING MEANS FOR AUTOMATIC SCREW IIJAGHIIUAS- Filed June '7, 1929 l 3 Sheets-Sheet 3 fr 100 j J0 v 7j /97 /jj Jaz 98 Patented June 30, 1931 UNITED STATES PATENT OFFICE JUDSON E. HANSFIELD AND CHESTER I'. lENROSE, OF BOC'KIFORI), ILI'INOIS, ASSIGNORS TO GREENLEE BROS. & C0., OF BOCKFORD, ILLINOIS, A CORPORATION F ILLINOIS THREAD CUTTING MEANS FOB AUTOI'IATIC SCREW MACHINES Application led June 7,

This invention relates to automatic screw machmes and 1s more partlcularly concerned withv providing improved thread-.cutting`- v called upon to feed themselves, the drag is means therefor. v

It has been thev practice heretofore, in the threading or tapplng operations on ascrew machine, to feed the die head or tap part-Way under spring pressure to cut the rst-few threads, and thereafter allow the die head or tap to ltake its own lead. The result was that at least the first thread orso was always more or less distorted because ofithe thrust imposed at the commencement of the cut by the spring pressure. This characteristic has been` so well recognized that it is` common practice where a short threaded piece is to be made, with say three or four threads, to make such work at least one or two threads longer than actually needed so as to compensate for the spoiling of the first part of the thread. The reliance upon spring pressure to-start the thread cutting also involved many mech'anical diiliculties. Numerous adjustments had to be made of the parts which determined the extent of the spring pressureavailable at the beginning of the cut and this required accurate adjustment of various parts, so that considerable skill was needed on the part of the operator in making the set-up. Then, too, there was the diiculty that these adjustments had to be changed later because the chasers in a die head when they are sharp will A require. less pressure to start them on the work than they will after they have been run for some time. These repeated adjustments all meant loss of time and considerably re-v duced the all around eiliciency of the ma' chine. Even thoughthese.disadvantages be overlooked, lthat i's,fthe almost invariable distortion of the first few threads on every piece of work turned out, and the trouble in making the set-up and later adjusting the same,

as Yjust described, there is still furtherto be considered the fact that machines having the die head or tap operated in that way were necessarily limited to the use of collapsible taps and self-opening die heads, which in 'the matter of tapping, placed a` definite limitation on the size of the work that could be handled. Moreover, these collapsible taps 1929. Serial No. 369,068.

and self-opening die heads involved greater tool cost than solid taps and dies, and not only that but where the tapszand dies are or die head, as the' case may be, having a nut in the end thereof threadedly enga 'ng the lead' screw, and change speed gearing or driving the tool spindle either slower than'the lead screw so as to produce axial movement of the -spindle in one direction, or faster 'than the .lead screw so as to produce axial movement of the spindle in the o posits-direction, or to drive the spindle at t e same speed .aS the lead screw so as to hold the same against axial movement. Thus, the tap or die head is ,therewith, is a tool spindle, carrying the Itap p arranged to be fed to the Work positively under lead screw control to the end of the cut, stopped, and returned again under the control of the lead screw, all without necessitating the use of any nicely adjusted startin spring pressure, or any spring pressure at al and without necessitatingl the use of a collapsible tap or self-o ening die head and, hence,

without introducing any danger-of, strippin v of threads or damage or brea age of the too In connection with the cha-nge speed caring, we provide a two-way clutchwhic when moved in one direction positively engages the high sneed gears, and when moved in the opposite direction positively engages the low speed gears, wherebv to provide vfor the driving of the'tool spindle at the two different speeds in relation to the speed of the lead screw, and associated with the two-way clutch is another clutch arranged to positively engage the gears for driving the tool spindle at the same speed as the lead screw whenever the two-way' clutch is in neutral position. Thus the tool spindle is always driven in a definite relation to the drivingof the lead screw, and the threads produced are accordingly-absolutely uniform from beginning to end with never an indication of any irregularity due to some peculiar stress on the tap or die head. "W e also provide means for automatically shifting the clutches, this means including a rocking lever arranged to be mounted to pivot either about one end thereof or about an intermediate point so as to communicate the push and pull of a control shaft one way to shift the aforesaid clutches correspondingly one way when a right-handed thread is being cut, and 'in the opposite way when a left-handed thread is being cut. Moreover, we have provided yielding connections between parts of the co-ntrol means, so that the operation of the mechanism is never attended with the danger of jamming of parts.

The invention is hereinafter described in detail by reference to the accompanying drawings, wherein- Figure 1 is what amounts to a; developed longitudinal section through part of an automatic screw machine showing our invention, the various spindles being shown in the same plane for the purposes of illustration:

Fig. 2 is a section on the line 2-2' of Fig, 1, showing the spindles in their true relationshipto one another;

Fig. 3 is a fragmentary view partly in section and partly in elevation, showing the automatic clutch-shifting means employed; Fig. t is a fragmentary sectional view on an enlarged scale of a part of the clutchshifting means appearing in Figs. 1 and 3;

Figy is a similar view of another part of said means which appears in Fig. 3, and Y Fig., 6 is a view on an enlarged scale of a portion of Fig. 3 taken on the line 6-16 thereof.

` The same reference numerals are applied to corresponding parts throughout the views.

The present invention relates to improvements in the type of screw machine disclosed in our copending application, Serial No. 211,387, filed August 8, 1927 and only so much'of the machine isfillustrated in this case as is essential to a good understanding of the various features to be discussed. Thus there is shown only a portion of the housing 6 provided at one end of the bed of the machine for the indexing head or turret in which the stock spindles 2" are mounted to rotate. Each ofA the spindles has a suitable collet chuck 8 at its outer end for holding the bar stock, the projecting end of which is represented at 9. We have not shown the tool slide slidably mounted on ways provided on the bed of the machine between the housing 6 and the gear box 10.. The slide carries the tools for cutting the stock in the four working positions presented by the four Stoch-carrying spindles terasse in the indexing head. nly two of the working positions appear in Fig. 1, the tool-carrying spindle 1l having a die head`12 on the end thereof 1for externally threading the stock 9, and the tool-carrying spindle 13 having a: tap 14 mounted in the end thereof to tap a hole indicated in dotted lines in the end of the stock 9'. The parts 15 are bearings by means of which the spindles 11 and 13 are supported on the tool slide (not shown). 1t should be understood that while we have shown the twospindles 11 and 13 with the die head 12 and tap 141-, respectively, the invention is not to be regarded as limited to the use of either or both in the same machine.

'In other words, the invention is applicable formed, and it would only be in the case of a special job that both operations might be required to be performed on the one machine. By illustrating both the die head and the tap, we only wish to make it clear that the invention applies to thread cutting generally.

A main drive shaft 16 extends lengthwise of the machine from the gear box 10 to the housing 6 into a center bearing in the indexing head in the latter, and constitutes the main drive shaft for driving the stockcarrying spindles 7 through suitable gears (not shown), the drive ratio being 1:1, so that the spindles turn at the same speed as the shaft 16. The shaft'l derives its power from a gear 17 driven through a train of change speedgears in the gear /box 10 by a motor mounted at the front of the machine, only the gear being shown. The latter is keyed, as indicated at 18, to a sleeve 19 keyed, as at 20, onto the end of the shaft 16. Now, another gear 21 is keyed at 18 to the sleeve 19 and meshes with two gears 22 and 23 for driving .lead screws 24 and 25 at the same speed as the shaft 16, and hence at the same speed as the stock-carrying spindles, the drive ratio between the gears 21-23 being 1:1. The lead screws 24C'and 25 are fastened removably in

sleeves

26 and 26 respectively, by means of keys 27 and 27', so that aleft-handed lead screw can be substituted for a right-handed lead screw when left-handed threads are to be cut, or vice versa. In other words, the

sleeves

26 and 26 serve as stocks or chucks for the lead screws detachably mounted therein. When the lead screws are changed, the nuts 28- and 28 fixed in the centrally bored end of the tool spindles 11 and 13, respectively, and threading on the lead screws will, of course, have to be changed also, these nuts being held in place lsuitably by means of a key and set screw (not shown). The lead screws must have a lead corresponding to that of thetap 14 and the chasers used in the die head 12. The ends of thetool spindles are splined, as

indicated at 29, for a sliding driving conioc . 7. However, it will presentl the latch 39 is arranged to nection with sleeves 30 and 30 coaxially arranged with reference to the sleeves 26 and 26', the former being mounted in roller bearings 31 and 31', and the latter in

roller bearings

32 and 32. provided therefor in the gear box. The splined connections between the tool spindles and the sleeves 30 and 30 are clearly shown at 33, the same being provided at one end of the sleeves. Itv will, therefore, be clear that the spindles 11 and 13 will turn at the same speed as the'sleeves 30 and 30. The sleeves 30 and 30 have

gears

34 and 35 keyed thereon meshing wlth a gear 36 mounted on anti-friction rollers 37 on the shaft 16, a hardened steell sleeve 38 being pressed into the front end of the sleeve 19 to serve as an inner race for the rollers just mentioned. Thus the sleeves 30 and 30 are interconnected to turn together, Iand they turn at the samel speed because ofthe drive ratio between the gears 34-36 being 1 :1. The gear 36 is arranged to be clutched to turn with the sleeve 19 so as ,to cause the sleeves 30 and 30 to be driven at the same speed as the shaft 16, and hence at the same speed as the

lead screws

24 and 25, and the stock-carrying spindles 7. The clutching means comprises a latch 39 pivotally mounted at 40 in a recess 41 provided inthe sleeve 19. A compression spring 42, fitting in a socket in the latch 39 and held in place within the hub of a gear 43 keyed on the sleeve 19, serves normally to urge the one end of the latch 39 inwardly into engagement in any one of a. series of notches 44 cut in the hub of the gear 36. The latch, therefore, constitutes a clutch and is arranged to be engaged or disengaged by means of a shifter sleeve 45 when the rounded projection on the other end of the latch moves into or out of an annular groove 46 provided on the inside of the sleeve 45, that being when the sleeve 45 is moved to and from the mid position in which the same appears in Eig. 1. Now, the sleeve 45, as we shall presently see, is arranged to be shifted from one limit position through the mid position to the other 'limit position in the changing of the drive of the tool spindles from low speed to high speed, or vice versa. In other words, when the high speed or low speed drive for the tool spindles is disengaged, the sleeve 45 is naturally in the mid position, and the gear 36 is clutched by the latch 39 to turn at the same speed as the shaft 16, and the tool spindles are, therefore, driven at the same speed as the shaft 16, lead screws 24 and 25 and stock-carrying spindles appear that e disengaged from the notches 44 as the gears for the high or low speed drive are about to be engaged. In other words, the latch 39 is disengaged before the gears for the high or low speed drive are engaged, and the latch is not arranged4 to be engaged before the gears for the high or low speed drive are disengaged. We shall now describe the low and high speed drives for the tool spindles.

A small gear 47, keyed on the sleeve 19, meshes with a larger gear 48` arranged to turn freely on the sleeve 30. Another gear 49, also arranged to turn freely on the sleevev 'and 49, is arranged when moved to the left from the neutral position shown to engage clutch teeth 51 on the gear 48, so as to drive the sleeve 30, and hence the spindles 11 and 13 4at a slow speed, slower than the drive shaft 16, lead screws 24 and 25 and the stock-carrying spindles. On the other hand, when thel sleeve 50 is moved to the right, it engages clutch teeth 52 provided on the side of the gear 49 and the sleeve 30, and hence the spin dles-ll'and 13, are driven at a highv speed, higher than/'the speed at which the shaft 16, etc., are turned. A single shifter yoke 53 has engagement with the sleeve 45 and collar 50, as best appears in Fig. 2, to move the same together. It is evident that when the collar 50 is in neutral position, the sleeve 45 is in mid pt tfm so as to permit the latch 39 to clutch the ver 3G to drive the tool spindles at the same spI f l as the lead screws 24. and 25, etc.,

but that when the collar 50 is shifted either way from neutral position to engageeither the low speed or the high speed gears, the sleeve 45 disengages the latch 39 so as to permit the gear 36 to turn at a different speed; lower than the speed of the shaft 16 when the low speed gears are engaged, and higher than the speed of the shaft 16 when the high speed gears are engaged, as should be evident from, the foregoing description. For example, these various gear combinations may be of such ratios as to make it possible to operate the tap or die at a speed which is, say, either a third slower than the lead screws, or else the same speed as the lead screws, or else a third faster than the speed of the lead `screws. The ratios employed obviously de# pend on the lead of the thread to be cut, the

lead of the lead screws being, 'as stated be# fore, always the same as the lead of the tap or die. In passing, it should be evident that the relationship of the lead screw and nut to the parts associated therewith may be reversed; the nut 28, for example, might be mounted where the lead screw 24 is mounted and driven at a constant speed, and the lead screw 24 might be carried onthe spindle 11 and arranged to turn with it at its diierent speeds. However, the arrangement shown is,

of course, preferred, as it presents obvious.4

advantages over a reverse arrangement. Claims to the arrangement should, however, be construed so as to cover a reversal 1n the relationship of these parte.

ln operation, assuming that the lead screws 24 and 25 are right-handed for the cutting of right-hand threads, at the beginning of the thread cutting operation, whether it be an external thread produced by means of a y,die head 12, or a tapped thread produced by a tap 14, the clutch collar 50 is shifted to the left to engage the low speed gears 47-48 so as to turn the tool spindles at a slower speed than the lead screws. That being the case, the nuts 28 and 28 hack up on the lead screws and move thetool spindles forwardly to feed the die head and tap onto the work to cut the threads. At the end of the thread, the clutch collar 50 is moved to neutral position, and when that'occurs the sleeve 45 is simultaneously brought to mid position to clutch the gear 36 by means of latch 89 to turn at the same speed as the shaft 16, whereby both of the tool spindles 1l and 13 are caused to turn at'the same speed as the lead screws 24 and 25 and the stock-carrying spindles 7. The nuts 28 and 28 are, therefore, turning at the same speed as the lead screws, and consequently, the feeding of the die head and tap is stopped. Naturally then, there is no need for opening of the die head or collapsing of the tap, asthe case may be; the parts simply assume a definite relation to one another and keep that relation. The die head may, of course, be arranged to be opened if desired, and a collapsible tap may likewise be used, if desired, but, as stated, there is no absolute need therefor. The yoke 54, appearing in Fig. 1, in connection with the die head l2, is, therefore, not' absolutely necessary since a solid die head might be employed. However, where a die head of the typearranged to be opened is used, a yoke, such as that shown, is employed mounted on a rod 55 slidable in aL fixed bearing 56. A collar 57 is set to come into engagement with the bearing 56 toopen the die head at the end of the thread. Another collar 58 is set to engage the other end of the bearing 56 to close the die head when the same arrives at its fully retracted position. To retract the die head and/orL tap, the 'tool spindle or spindles are arranged to be sped up to a speed beyond that ofthe lead screws and stock-carrying spindles by shifting the clutch Icollar 50 to the right to engagev the gears 43-49. With these gears engaged, the latch 89 being at the same time disengagedby reason of movement ofthe sleeve 45 to the right with the collar 50, the nuts 28 and 28T are turned at a higher speed lthan the lead screws 24 and25 respectively, so that, instead of backing oifthe lead screws as before, they thread onto the same and thereby return the tool spindles and retract the die head and tap therewith from rsaeeo the work. Briefly stated, therefore, the die head or-tap, in the case of a right-hand thread, is fed to the work by the driving of the spindle at a slower rate of speed than the lead screw, and is backed away by speeding it up faster than the lead screw. ln cutting a left-hand thread, a left-handed lead screw and nut will, of course, be required, and in that case, the spindle is driven faster than the lead screw to feed the die head or tap to the work, and is driven at a slower speed to back it olf. In either case when the die or tap is in the retracted or idle position, and also when it is on the work at the end of the thread, it is obviously necessary that the spindle be driven at the same speed as the lead screw, so that the nut threading on the lead screw will not have any movement relative thereto. Such a drive is provided for by the clutching of the gear 36 in both of these instances, as fully described above.

The shifter yoke 53 is fastened to a shifter rod 59 reciprocable in bearings 60 and 61 in the gear box l0. The rod 59 has a pin and slot connection at 62 with a rocker lever 63 arranged to he pivoted by means of a pin 64 to a bracket 65 provided on the outside of the gear box'lO. The pin 64 is removable and insertable by hand in either one of two sets-of registering

holes

66 and 66", and 67 and 67 provided in the bracket 65 and lever 63, respectively, for a purpose we shall presently explain, the pin 64 being herein shown as entered through the registering holes 66 and 66 so that the lever 63 swings about the one end thereof relative to the bracket 65. A wire spring 68, mounted in a lug 69' into which the spring 68 may enter to hold the pin securely in place. Now, the lever 63 is pivoted at 70 to a stop shaft 71. The location of the pivot 70 is significant; it will be noticed in Fi 5 that the distance from the point 70 to t e point 66 is approximately equal to two-thirds the distance from the point 66 to the point 62, and that the distance from the point 67 to the point 62 is also approximately equal to two-thirds the distance from the point 62 to the point 70. It makes no difference, therefore, whether the pin 64 provides a pivot at 66 or 67; the stop shaft 7l will communicate a greater movement to the rod 59 whenever 'it is moved itself through a certain distance, the ratio of the movement of the shaft 7l to the movement of the rod 59 being approximately as 1:11@ However, it will be seen that when the pin 64 provides a pivot at 66, the shaft 7l is arranged to move the rod 59 in the same a ball bearing 74 at the other end providing a connection with the tool spindle 11 to cause the bracket 72 to move back and forth with the spindle in its feed and return movements.

Stops

75 and 76 are adjustably secured on..the shaft 71 ateitherside ofthe bearing 73. Thus, at the end of the forward travel of the-tool spindle, the stop 75 is arranged to be engaged to move the shaft 71 in the one direction to shift the clutch collar 50 to neutral position so as to disengage the one set of earsl and stop the lead screw feed of the spindle, the spindle being then driven at the same speed as the lead screw by reason of en agement of the latch 39 with the gear 36.l Afgter that the shaft 71 is arranged to be moved endwise, in a manner we shall presently explain, to shift the clutch collar 5 0 to engage the other'gears to bring about the return of the tool spindle. ,At the end of the return travel, the stop 76 is arranged to be engaged by the bearing 73 to move. the shaft 71 1n the opposite direction to disengage the clutch collar 50. Now, it should be evident that when a right-hand thread is being cut, the pin 64 provldes a pivot for the lever 63 at the one end thereof, so that the rod 59 is shifted in the-same direction jas the shaft 71.

Thus, the low speed gears 47-48 are engaged during the feed movement of the tool spindle and are arranged to be disengaged by movement of the clutch collar to the right when the sto 75 ismoved to the right at the end of the feed movement of the spindle. Then, the high speed gears 43-49 are yengaged for the return movement of the tool spindle and are arranged to be disengaged by movement of the clutch collar 50.to the left caused by movement of the stop 76 to the left at the end of the return movement of the tool spin- -dle. On the other hand, when a left-hand thread is being cut, the high speed gears are engagled during the feed movement of the spm e,'and at the end of theL feed move'- ment, ,the clutch collar 50, to'be disengaged, must be moved to the--left by movement of the stop 75 to the right. Hence,the 4necessity dfor the shifting of the pivot pin 64'to the intermediate positin in order that the 'lever- 63 will constitute aA reversing connection between the shaft 71 and rod 59. Similarly, at the end of the return movement of the spindle, the low 4speed gears are disenthe disengagement of the clutch co1lar'50 is" taken care of just as Well in one case as in Y. the other. In passing, it will be observed in Fig. 3 that a plunger 77 slidably mounted ina hole 78 in the wall of the gear box 10 communicating with the bearing 61, has the V-shaped end thereof normally urged toward engagement in either one of three notches 79, 80.4.and 81 by means-.of a compression spring 82 bearing against the back of theplunger. The middle notch' 80 is fairly deep, and when the plunger 77 engages in this notch, the clutch collar 50 is in neutral position and the sleeve 45 correspondingly in mid position. When the plunger engages in notch 7 9, the low speed gears 47--48 are engaged, and when the plunger engages notch 81, the high speed gears 43-49 are engaged.

Referring now to Figs. 3, 4 and` 6, shaft 83 constitutes the l'main cam shaft for controlling all of the vvarious movements of the screw machine. It is shown as havinga gear drive in the housing 84 provided on one side of the bed of the machine. A cam disk 85 is mounted on the shaft 83 outside the housing 84 and `has a dog 86 fastened on one side thereof, and

married on thf side of the housing 84. The

bell crank lever 92 has an arm 95 on the upper end thereof, which is suitably bifurcated Y at its free end for pivotal connection 96 with a sleeve 97. The sleeve 97 receives the reduced end 98 of the stop shaft 71, previously referred to. Two-

rings

99 and 100, with a. coiledk compression spring 101 therebetween,

lit on the reduced end 98 of the shaft 71, the

ring 99 normally in engagement with the annularshoulder 102, and the `ring 100 held by a washer' and nut at 103 and normally resting in engagement with an annular shoulder 104 provided on the inside of the sleeve 97 A gland nut 105 threadingon the end of the sleeve 97 completes the connection, and it will be seen that the shaft-71 can move in either direction relative to the sleeve 97 against the pressure of the spring 101 for a purpose that will presently appear. Now, the sleeve 97 ,has two

notches

106 and 107 cut in the side thereof, into either one of which a roller 108/is arranged to engage. The roller 108 is carried by a lever 109 pivoted at 110 on the bracket 94. The lever carrying the roller is urged toward the sleeve by means of a heavy coiled compression spring 111 disposed in a hole 112 providedin the bracket 9d.

ln operation, assuming that the tool spindles 11 and 13 with the die head 12 and tap 14- are backed away froml the work, the main cam shaft 88 in the course of a turn brings the cam disk 85 around to a position where the dog 86 engages the roller 90 and forces it to the right, as it is viewed in Fig. 3. Thus, the shaft 71, shifter rod 59, and clutch collar and sleeve 45, are thrown to the left to engage the low speed gears 47-48 so as to reduce the speed of the tool spindle or spindles to a speed below that of the lead screw or screws to feed the die head and/or tap to the work as previously described. When the shaft 71 has been moved to the left, the roller 108 is engaged in notch 107 to hold the clutch collar 50 and the clutch shifting means in position until the bracket 72 in moving with the tool spindle 11 engages and moves the stop 75 to shift the shaft 71 to the right, in the manner previously described, to disengage the clutch collar 50. The endwise movement of shaft 71 produced by actuation of the stop 7 5 in the manner stated, will force the sleeve 97 to the right just enough to bring the roller 108 in engagement on the dat be tween the

notches

106 and 107 the clutch collar 50 and shifter sleeve d5 being then in neutral or Amid position. The pin and slot connection at 62 between the rod 59 and lever 63 permits a little play between the shaft 71 and the rod 59. rEhe bracket 72 forces the shaft 71 endwise until the rod 59 has pulled the clutch collar 50 out of engagement with the teeth on gear 4&8, at which time the plunger 77, by reason of its V-shaped end riding out of the notch` 79-a11d part way into the notch 80, will move the rod 59 under the impulse of the spring 82 independently of further movement of the shaft 71 to bring the clutch collar 50 and shiftersleeve 45 to the neutral or mid position. lhey keep this position until the dog 87 comes into engagement with the roller 90 and moves the same to the left as itis viewed in Fig. 3, thus pulling the shaft 71 and rod 59 to the right to engage the clutch collar 50 with the teeth 52 on the gear 49 to throw the high speed gears 43-49 into action. When the sleeve 97 moves to the right, the roller 108 drops into the notch 10G so as tohold the clutch collar -50 and the clutch-shifting means in their new positiom During this `operation of the tool' spindle at a higher speed than the lead screw, the spindle is backed away neiaeee from the work and continues to do so until the stop 76 is engaged by bracket 72, and the shaft 71 together with rod 59 is` moved. to the left to bring the clutch collar 50 and shifter sleeve d5 to neutral or mid position. rllhe cycle of Jfeed and return of the tool spindle or spindles is, of course, repeated again and again in the continuous operation of the screw machine. live have described the cycle any possibilityoic jamming. For example,-

cam disk 85 may turn so slowly that the

dogs

86 and 87 after operating the roller 90 one way Aor the, other may not happen to be movedentirely clear of the roller at the instant the shaft 71 is moved by the bracket 72. If that occurs, the spring 101 is simply placed under slight ladditional compression until the disk 85 has had time enough to turn a little farther to bring the obstructing dog clear of the roller.

ln setting up, as for example, for threading with a die head, it is necessary to provide a lead screw and lead screw nutl at 24 and 28, respectively', having a lead corresponding to the lead of the die head. chasers being used. rlhe machine is then started to feed the die head onto the stock the required ydistance whereupon the machine is stopped. rlhen the collar 57 is set to open the die head, and the stop collar 75 is set to bring the clutch collar 50 and shifter sleeve 'i5 to neutral mid position. The cam do 87 is then adjusted and fastened in a position where it engages the cam roller 90 to throw the high speed gears into action to back the die head off the stock, and the machine is then started up, and when the die head has.

cleared the work, the machine is stopped again. Then the collar 58 is set to close the die head, and stop collar 76 is set to throw again to reduce the diameter of the thread,

after which the work is again tested andthe procedure repeated until the proper diameist ter is reached. This simple procedure is rendered possible, dueto. the fact that the lead screw will feed the die head back onto the work onto the same thread. =Heretofore,

where the old style of threading mechanism was.emp1oyed, the chasers could not be brought back onto the same thread, and consequently a new piece had to be used for each test, the disadvantages of which must be self-evident. In tapping small holes requiring a solid tap, the yoke 54 used with a collapsing tap or die head can, of coursel be dispensed with so that the set up for this class of work is extremely simple.

y The spindle 13 is nt limited for use in tapping, but niay be employed to feed nonrotating tools carried on the tool slide, such as reamers, counter-sinks, facing tools, etc. Tools of that kind can befu'sed in either the third or fourth spindle positions and are especially advantageous in the fourth position. The work is usually cut off from the bar in the fourth position by a tool carried on the cross feed slide. With any tool fed by thethreading device in the fourth position, it is possible to perform an extra operation such as reaming or counter-boring, and get'the tool backed away clear of the work before the cut-olf. v p l It is believed the foregoing description conveys a clear understanding of all of the objects and'. advantages of our invention. While we have referred to various specific details of construction in the course of this specification, it should be understood that invention is not limited thereto, but that many changes might be made without seriously departing from the spirit and scope of the invention. The appended claims have,

` "o therefore, been drawn with a view to cover- ,ing all legitimate modifications and adaptations which no doubtgwill occurV those skilled in the art to which this invention relates.

We claim:

1. In a machine of the character described, the combination of one or more lead screws, one or more stock-carrying spindles arranged to be disposed coaxial with the lead screws, means for driving the screws and stockcarrying spindles at the same speed, the tool spindles having nuts carried thereby threading on the lead screws, and means for driving the tool'spindles and nuts carried thereby at the same speed as the lead screws to hold the` same against axial movement, or slower than the lead screws to produce axial movement of the tool spindles in one direction, or faster than the lead screws to produce axial moveo ment of the tool spindles in the opposite direction.

2. In a machine of the character described, the combination of one or more lead screws,- one yor more tool spindles, one' or more stockcarrying spindles coaxial therewith, the lead 'relative to the other spindles is desired in the y opposite direction.

and return '3. In a machine of the character described, l

the combination of one or morestock-carrying spindles, means for driving the same at a certain speed, one or more tool spindles coaxiallyl disposed with respect to the stock- .1

carrying spindles, means for feeding and returning the tool spindles comprising one or.'

more lead screw elements having nut elements threading thereon, and means for driv ing the elements, both at the same speed as i -the stock-carrying spindles when thev tool y spindles are to be held against axial movement, anddriving the one set of elements to turn relative to the other set of elements.

when axial movement of the tool spindles in one direction is desired, and vice versa for axial movement of said tool spindles in the opposite direction.

4. Thread-cutting mean's\ such as a screw machine, comprising a stockcarrying spindle, a tool-carrying spindle coaxially disposed with respect thereto and carrying a thread-cutting tool, means for driving the first spindle at acertain fixed speed, and means for communicating move- -ment to the tool spindle comprising .a lead screw and a nut threading thereon, the one part being held against endwise movement and being driven at a certain fixed speed, and the other partbeing movable endwise and being arranged to communicate .movement to the tool spindle, and means for' driving the latter part with the tool spindle at the same for a machine,

speed as the other p art when no movement of the tool spindle i's desired, or slower than said other part when movement of the tool spindle in one direction is desired, or faster than said other part when'movement of the tooll spindle in the opposite direction is desired.

5'. Thread-cutting means for. a machine, such as a screw machine, comprising in comhina-tion, a stock-carrying spindle, a lead screw spindle and a tool-carrying spindle disposed preferably in coaxial alignment, the

latter having a tool at one end to engage the. work carriedby the stock-carrying spindle and having a nut at the other end threading on the lead screw spindle, and means for driving al1 of said spindles atthe same speed when'the tool-carrying spindle is in its limitpositions at the endV of the feed and '.return. movements thereof, and driving the lead fill screw and stock-carrying spindles faster than the tool-carrying spindle to produce. the one movement of the latter and slower than the same to produce the other movement thereof.

6. 1n a machine of the character described, the combina-tion of a drive shaft, one or more stock-carrying spindles driven by the drive shaft at a certain speed, one or more lead screws driven by the drive shaft at the saine speed as the stock-carrying spindles, the latter being arranged to be disposed coaxial with t-he lead screws, one or more tool spindles carrying thread-cutting tools, the same being disposed coaxial with the stock-carrying spindles for operation of the thread-cutting tools on the work, the tool spindles having nuts mounted in the ends thereof threading on the lead screws, gears for providing a driving connection between the .drive shaft and the tool spindles fory driving the latter at the same speed as the lead screws, other gears for providingl a driving connection between the drive shaft and the tool spindles for driving the latter at a lower speed than the lead screws, still other gears for providing a driving connection between the drive shaft and the tool spindles for driving the latter at a higher speed than the lead screws, clutching means for selecting either of the last two mentioned sets of gears to drive the tool spindles slower or faster than the lead screws, and clutching means for throwing into action the first set of gears when the two other sets of gears are thrown out of action.

7. The combination set forth in claim G including means interconnecting the clutching means whereby when the former is shifted to disengaged position, the latter is shifted simultaneously to engaged position, and vice versa.

S. In a machine of the character described, the combination of a main drive shaft, a plurality of stock-carrying spindles disposed about the same in parallelism therewith and driven thereby at a cert-ain speed, a plurality of lead screws disposed about the drive shaft in parallelism therewith and driven thereby at the same speed as the stock-carrying spindles, the stock-carrying spindles being arranged to be disposed in coaxial relation with the lead screws, a plurality of tool spindles disposed about the drive shaft in parallelism therewith coaxial with the lead screws, the tool spindles having tools mounted on the one ends thereof, such as thread-'cutting tools, for operation on the work carried by the `stock-carrying spindles and having nuts carried on the other ends thereof threading on the lead screws, gears for providing a driving connection between the drive shaft and the tool spindles for driving the latter at the same speed as the lead screws, other gears for providing a driving connection between the drive shaft and the tool spindles for driving the latter at a slower speed than the lead screws, still other gears for providing ay driving connection between the drive shaft and the tool spindles for driving the latter at a higher speed than the lead screws, clutching means for selecting either of the last two mentioned sets of gears for driving the tool spindles slower or faster than the lead screws, and clutching means associated with the first set of gears for throwing the same into action whenever the other two sets of gears are out of action.

9. The combination set forth in claim 8 including means interconnecting the clutching means whereby when the former is shifted to disengaged position, the latter is shifted simultaneously to engaged position, and vice versa.

l0. In a machine of the character described, the combination of a drive shaft, one or more stock-carrying spindles driven at a certain speed, one or more tool spindles disposed coaxial with the stock-carrying spindles having tools, such as thread-cutting tools, carried on the end thereof for operation on the work carried by the stock-carrying spindles, one or more lead screws for the tool spindles disposed coaxial with the latter, the lead screws being driven at the same speed as the stock-carrying spindles, the tool spindles having nuts on the other end thereof threading on the lead screws. the latter end of said tool spindles being splined for a sliding driving connection with sleeves fitting on the same, a sleeve on the drive shaft adjacent the last mentioned sleeves, a gear fixed on the drive shaft sleeve meshing with a gear free to turn on one of the tool spindle sleeves to provide a drive for the spindles at a slower speed than the lead screws, a second gear fixed on the drive shaft sleeve meshing with a gear free to turn on the same tool spindle sleeve to provide a drive for the tool spindles at a higher speed than the lead screws, a clutch collar on said tool spindle sleeve between the two gears thereon shiftable in either direction to clutch either gear to the sleeve to drive the tool spindles slower or faster than the lead screws as desired, a third gear free to turn relative to the ,drive shaft adjacentthe end of the drive shaft sleeve meshing with gears fixed on the tool spindle sleeves serving to interconnect the tool spindles so they all operate at the same speed, and clutchingmeans for turning the third gear with the drive shaft sleeve to drive the tool spindles at the same speed as the lead screws whenever the first mentioned clutch collar is in neutral position.

11. The combination as set forth in claim l0 including means interconnecting the clutch collar with the last mentioned clutching means whereby in the movement of the clutch collar to and from neutral position,

theJclntching means is simultaneously moved to and from en aged position.

12. The com ination as set fort-h -in claim 10 including automatic clutch control means comprising a shifter element shiftable to andV fro to move the clutch collar selectively in either direction, a control shaft movable to and fro, means for automatically communicating movement to the control shaftin one di cection or the other for the purpose of shifting tle clutch collar, and means for selectively and interchangeably providing a unidirectional connection between said control shaft and said shifter element or a reversing connection between the same for the purpose described.

13. The combination as set forth in claim 1'0 including automatic clutch control means comprising a shifter element shiftable to and fro to move the clutch collar selectively in either direction, a'ycontrol shaft movable to and fro, means for automatically communicating movement to the control shaft in one directionA or the other for the purpose of shifting the clutch collar, means for selec- -means is simultaneously moved to and from engaged position.

In a machine of the'character del scribed, the combination of one or more stockcarrying spindles driven at a certain speed, one or more tool spindles coaxial therewith having tools, such thread-cutting tools, carried on one end thereof for operation on the work carried by the stock-carrying spindles, one or more lead screws coaxial with the tool spindles and driven at the same speed as the stock-carrying spindles, the tool spindles having nuts carried at the other end thereof threading on the lead screws, gears for driving the tool spindles at a slower speed than thelead screw's, other gears for driving the tool spindles at a higher speed than the lead screws, clutching means for 'selectively engaging either set of gears, gears for driving the tool spindles at the same speed as the lead screws, and clutching means for engaging said gears whenever the first mentioned clutchlng means is in neutral posltion.

15. 'In a machine of the character described, the combination of oneor more stock-carrying spindles driven at a certain speed, one or more tool spindles coaxialtherewith having tools,

by the stock-carrying spindles, one or more lead screws coaxial with the tool spindles and driven at the same speed as the stock-carrying spindles, the tool spindles havin nuts carried at the other end thereof thre ing on the lead screws, gears for driving the tool spindles at a slower speed than the lead screws, other gears for driving the tool spindles at a higher speed than the lead screws, clutching means shiftable in either direction from a middle neutral position for selectively engaging either set of gears, gears for driving the tool spindles-at the same speed as the lead screws, and clutching means shiftable with the first mentioned clutching means in either direction from a middle engaged position for engaging said gears Whenever the first mentioned clutching means is in neutral position.

16. The combination set forth in claim 15 including a shifter element associated with the clutching mea-ns and shiftable to and fro., a control shaft also shiftable to and fro and arranged to beshifted in either direction for the purpose of shifting the clutching means, and means for selectively and interchangeably providing either a unidirectional connection between the shifter element and control shaft for moving the shifter element in the same direction as the control shaft in the operation of the latter, or a reversing connection between said element and shaft for moving the element in the opposite direction when the control shaft is movedin a certain direction for the purpose herein described,

the last mentioned means comprising a fixed support, a rocker lever having the shifter element and control shaft pivotally connected thereto at two spaced points, and a removable pivot pin for pivotally mounting said lever on said support, the said pin being arranged to be removed from one position and inserted in another position on said support whereby to have the lever pivoted on said support either at a point between the said pivotal connections or at another point not between said pivotal connections.

17. The combination set forth in claim 15 including a shifter element associated with the clutching means and shiftable to and fro, a control shaft also shiftable to and fro and arranged to be shifted in either direction for the purpose of shifting the clutching means, and means for selectively and interchangeably providing either a unidirectional cona fixed support providing spa-ced parallel flanges, a lever on said fixed support between the flanges having the shifter element and control sha-ft pivotally connected thereto permanently at two spaced points, the said lever being arranged to be pivoted on said support either at a point between the said pivotal connections orat another point not between said pivotal connections, and a pivot pin removably insertible through either one of two sets of registering holes provided in the lever and in the flanges of said support for the purpose contemplated.

18. The combination set forth in claim 15 including a shifter element associated with the clutching means and shiftable to and fro, a control shaft also shiftable to and fro and arranged to be shifted in either directionl for the purpose of shifting the clutching means, and means for selectively and interchangeably providing either a unidirectional con' nection between the shifter element and control shaft for moving the shifter element in the same direction as the control shaft in the operation of the latter, or a reversing connection between said element and shaft for moving the element in the opposite direction when the control shaft is moved in a certain direction for the purpose herein described, the last mentioned means comprising a xed support providing spaced parallel flanges, a lever on said fixed support between the flanges having the shifter element and control shaft pivotally connected thereto permanent- 1y at two spaced points, the said lever being arranged to be pivoted on said support .either at a point between the said pivotal connections or at another point not between said pivotal connections, a pivot pin removably insertible through either one of two sets of registering holes provided in the lever and in the flanges of said support for the purpose contemplated, and means on the outside of one of said flanges for quickly detachably securing the pivot pin in position in either set of holes.

19.` The combination as set forth in claim 15 including a shifter element associated with the clutching means for operating the same in either direction, a reciprocable control shaft for operating said element, a dog actuated member arranged to move said Shifter element through the medium of saidlshaft in one direction to engage the low speed gears and in the opposite direction to engage the high speed gears, stops on said shaft, a part movable positively with one of said tool spini dles to engage the one stop at the end of the feed of the spindles to move said shaft and disengage the one set of gears and to engage the other stop at the end of the return of the spindles to move the shaft in the other direction to disengage the other set of gears, and means providing a yielding connection between said shaft and the dog actuated mem- "dles relative to the other kind of spindles, and

means for driving the elements both at the same speed as the other spindles to prevent axial movement, and driving the one set of elements to turn relative to the other set of elements when axial movement with respect to the other spindles is desired in one d1rection, and vice versa for axial movement in the opposite direction 21. Thread cutting means for a machine, such as a screw machine, comprising a stockcarrying spindle, a tool-carrying spindle coaxially disposed with respect thereto and carrying a thread cutting tool, means for driving the one spindle at a certain fixed speed, and means for communicating movement to the other spindle comprising a lead screw and a nut threading thereon, the one part being held against endwise movement and being driven at a certain fixed speed, and the other part being movable endwise and being arranged to communicate movement to the spindle, and means for driving the latter part with the spindle at the same speed as the other part when no movement of the spindle relative to the other spindle is desired, or

slower than said other part when movement of the spindle is desired in one direction, or faster than said other part when movement of the spindle is desired in the opposite direction.

22. Thread cutting means for a machine, such as a screw machine, comprising, in combination, a stock-carrying spindle,`a tool-carrying spindle disposed in coaxial alignment therewith, and a lead screw spindle coaxially disposed with reference to one of the aforementioned spindles, the latter spindle having a nut threading on the lead screw spindle, and means for driving all bf said spindles at the same speed to maintain a given relationship between the tool-carrying and stockcarrying spindles, and driving the lead screw spindle and the other spindle not threaded thereon faster than the remaining spindle to produce movement of the latter in one direction, and slower than said spindle produce the other movement thereof.

23. In a machine of the character described, the combination of a drive shaftpne or more stock-carryingl spindles, one or more ,tool-carrying spindles, the one kind of spindles being driven by the drive shaft at a certain speed, one or more lead screws driven by the drive shaft at the same speed ossazid spin- -ing connection between the drive shaft and said spindles for driving the latter at the same speed as the lead screws, other gears forl roviding a drivin connection between the rive shaft and sai s indles for driving the same at a lower speed tiian the lead screws, still other gears for providing a driving connection between the drive shaft and said spindles for driving 'the latter at a higher speed than the lead screws, clutching means forselecting either of the last mentioned sets of gears so as to drive the spindles slower or faster than the lead screws, and clutching means for throwing into action the first set of gears when the two other sets of gears are thrown out of action. l

24. The combination set forth in claim 23 including means interconnecting the clutch means whereby when the lformer is shifted to disengaged position, the later is shifted simultaneously to engaged position, and vice Versa..

25. In a machine of the character described,

. the combination of a main drive shaft,a pludles being drlven by the drive shaft at a cer-I tain speed, a lurality of lead screws disposed coaxiaily with the other kind of spindles and driven by the drive shaft at the same speed as the first spindles, the other spindles having nuts threading on the lead screws, gears for providin a driving connection between the drive s ft and Said spindles for driving the latter at the same speed as the lead screws, other gears for providing a driving connection between the drive shaft and said spindles for driving the latter at a slower speed than the lead screws, still other gears for providin a driving connection between the drive aft and said spindles for driving the latter at a higher speed than the lead screws, clutching means for selecting either of the last two mentioned sets 'of gears for driving said spindles slower or ,I coaxial therewith, one or more chucks having lead screws detachably mounted thereon, the lead screws cooperating( with nuts detachably carried by the one ind of spindles to feed and return the same relative'to the other kind of spindles, and means for driving the nut-carrying spindles at the same speed as the lead screw chucks when no axp ial movement vof the spindles relative to 'the' other spindles is desired, or at a slower speedI than the lead'screw chucks for axial movement in one direction or faster than the lead vscrew 'chucks for axial movement in the oppoi .m

site direction. p

27. In a machine of the character described, the combination of on'e-or more stockcarrying spindles, means for driving the same at a'certain speed, one or more tool spindles coaxially disposed with respect to the stockcarrying spindles having tools, such as thread cutting tools, carried on the end thereof for operationen the work carried by the stockcarrying spindles, one or more chucks having lead screws detachably mounted thereon disposed coaxial with the tool spindle-s, the lead s'crew chucks being driven at the same i speed as the stock-carrying spindles, the tool spindleshavin nuts detachably carried at the other end t ereof threading on the lead screws, and vmeans for driving the tool spindles and nuts carried thereby at the same;

speed as the chucks and lead screws carried thereby to hold the tool spindles against ax-l ial-movement, or slower to produce axial movement of the tool spindles 1n one dlrection, or faster to produce axial movement of the tool spindles in the opposite direction.

28. In a machine of the character described, the combination with one or morev dles and to be moved axially while driven faster or slower, of a shifter element associated with clutching means for determining the vdrive of the spindles and arranged to be movedin either d1rection, a reciprocable control shaft for operating said element, a dog actuated member arranged to move said shifter element through the medium of said shaft in one direction for low speed and in.A

the opposite direction for high speed, stops on said shaft, a part movable positively 1n the axial movement of the spindles to engage the one stop at the end of the movement of the spindles to move said shaft for the operation of clutching means and to engagethe other stop at the end of the return move.- ment of the spindles to move the shaft in the other direction to again operate theclutching means, andA means providing a yielding connection between said shaft and the dogactuated member permitting constrained movement of onepart with reference tothe other in either direction for the purpose'described.

29. A machine as set forth in claiui 28.

wherein the shaft has an end portion telescoping within a tubular part on the dog actuated member 'and arranged lfor endwise 1 compression spring in said tubular part fitting about the end portion of said shaft, the spring being held against endwise movement bodily in said tubular part in either direction but being compressible by means of said shaft in the movement of the latter in either direction relative to the tubular part.

30. A machine as set forth in claim 28 wherein the shaft has an end portion telescoping, within a tubular part on the dog actuated, member and arranged for endWise movement with respect thereto, there being a 4 compression spring in said tubular part it ting about the end portion of said shaft, the spring being held against endvvise movement bodily in said tubular part in either direction but being compressible by means of said shaft vin the movement of, the latter in either direction relative to the tubular part, the end port@ tion of said shaftbeing reduced whereby to provide an annular shoulder, a ring fitting slidably on the reduced end portion of said shaft adjacent the annular shoulder and reciprocable in the tubular part, but limited in g5 its movement in said part in one direction, the ring having one end of the spring engaging the vsame and being arranged to compress the spring in the movement of the shaft in one direction but to serve as an abutment for the spring in t-he movement of the shaft in the other direction, and a second ring slidably mounted and retained onthe end of the re- 4duced portion of the shaft and arranged to reciprocate in the tubular part but limited in its movement in said part avvay from the first ring and serving to compress the spring in the movement of the shaft in one direction and serving as an abutment for the spring in the movement of the shaft in the 4other w direction.

In Witness of the foregoing We afix our signatures. Y

JUDSON H. MANSFIELD. CHESTER F. PENRSE.