US2496663A - Metalworking apparatus - Google Patents

Description

Feb, 7, 190 F. A. FRITZSCH METAL WORKING APPARATUS 4 Sheets-Sheet 1 Filed June 14, 1946 I N VEN TOR.

Feb. 7, 1950 Filed June 14, 1946 F. A. FRITZSCH 2,496,663

METAL WORKING APPARATUS 4 Sheets-Sheet 2,

4 Sheets-Sheet 3 F. A. FRITZSCH METAL WORKING APPARATUS Feb. 7, 1950 Filed June 14, 1946 mm Q1 4 Sheets-sheet 4 F. A. FRITZSCH METAL WORKING APPARATUS Feb I,} 1950 Filed June 14, 1946 Patented Feb. 7, 1950 UNITED STATES PATENT OFFICE 'METALWORKING APPARATUS LFrankVA. .Fritzsch, Cincinnati, Ohio, aassignor to The :Lodge and Shipley Company, Cincinnati,

Ohio, a corporation of Ohio Application June 14, 1946, Serial No. 676,735

dillaims. :1 'This invention relates :to metal working, and 'is concerned particularly :with operations upon shafts of a type which heretofore'were shaped :at considerable expense and with questionable accuracy, using methods and apparatus not well adapted to the work. 7

One of the-"objects of the-invention is to provide a greatly improved method and means of shaping a complex shaft, whereby production time and costs "are substantially reduced, with a 'maked improvement in quality, finish, and accuracy resulting.

Another object is to provide -a-novel method and means for rapid turning "and forming of shafts having sections of different diameters,

"with the elimination of steady rests and-similar auxiliary supports heretofore "considered necessary to proper production of such shafts; the

- improved method'and apparatus making possible *the removal of metal at'ahigh-rate in the'turn- :ing and forming of the shaft, without chatter and the danger-of springing the shaft.

Another object of the invention is to'provide a special tailstock assembly for a lathe, adapted to facilitate and expedite the production of complex shafts of the character mentioned'above.

The foregoing and other objects are attained by'the meansdescribed herein-and'illustrated in the accompanying drawings, in-which:

Fig. 1 is-an elevational viewofa lathe embody 'ing the means of the invention.

Fig. 2 is an enlarged elevational view of the tailstock end of the lathe, parts being broken away.

Fig. 3 is an enlarged cross-sectional view taken on line 3-3 of Fig.2.

Figs. 4 to '12 inclusive,'are diagrammatic views illustrating a representative succession of operation steps constituting the method of the in- 'vention.

:Fig. 13 is a side view of -a modified headstock chuck arrangementfor the machine.

Inthe production of large shafts-characterized by frequent changes of contour and diameter,

such as the cam-shaftsof Diesel engines and the like, it has been customary heretofore to-prepare blanks by means of drop forging and turning processes, which presented-various disadvantages and objectionable limitations. in-the case of the drop forging process, the dies were "very expensive and many instances they were discarded long before the expiration of their useful life period because of the limited demand for such L'blanks, or the ifrequencymf changes :inthedesign thereof. The fforging die costs -'thereby were and tedious, resulting in high cost per unit manufactured.

To overcome the disadvantages above mentioned, long shafts were sometimes made-up of sections bolted or otherwise joined together after machining, but such procedure likewise increased tne costof production becauseof the additional .20-

handling and assembling stepsinvolved.

The method and means of the present invention are effective for obviating all ofthe common disadvantages .and limitations of the prior processes, with the result that production time and labor costs are'materially reduced, while at the same time the accuracy and finish of the blanks produced are greatly enhanced, without ahigh percentage of rejects occurring. By means :of :this invention, bar stock of any length can be used to advantage for making a one-piece blank, and all excess stock is removed at maximum speed *to produce the blank quickly and eiiiciently vwithout theaid of special supports at thecutting or forming tools. No limitations or restrictions on production are imposed, other than the horsepower 'of the machine and the life of its cutting tools. Maximum chip removal is provided for throughout the procedure, as the work-piece is always gripped at its largest diam- -:.eter and is firmly supported at all times without the use of a steady rest or other auxiliary attachment, while the cutting is performed close to the driving spindle and chuck of the machine.

One feature of the invention which is responsible for the desirable results obtained, is

the special tailstock or work-piece positioner of Figs. 2 and 3, which performs the functions of the steady rest or other auxiliary work-piece support throughout the turning and forming-operations upon the blank, while permitting the tools to operate in close proximity-to the driving spindle chuck. The improved tailstock performs other functions also, with respect to positioning and ,re-positioning the work-piece relative to the tools, in aprecise andexpeditiousmanner.

The machine of the invention is a lathe comprising the usual bed It having carriage ways l5-l5 and tailstock ways l6l6 extending longitudinally of the bed and adapted to support and guide the carriage I! and the tailstock indicated generally at l8. The usual leadscrew l9 and feed rod 20 are provided for moving the carriage longitudinally of the bed, and for moving the tool slide or slides 21 transversely of the bed, in accordance with common practice. In addition to the power means for so actuating the carriage and the tool slides, these elements may be moved manually by means of hand wheels or other devices 22 and 23. As is usual in machines of this type, a mechanical apron control rod 24 may be provided, including length feed stops 25 and 26 which are adjustable along the rod, and which function to automatically limit the extent of carriage movement in opposite directions longitudinally of the bed, through the agency of trip means located within a trip box 27. In addition to the adjustable automatic length feed device, the machine may be equipped also with means for automatically advancing and retracting the tools relative to the work-piece, thereby to render the turning and forming operations of the tools completely automatic, if desired.

The machine is provided with the usual feed box 28 and quick change gear box 29, including the means necessary for the automatic functions above related. The mechanisms for performing said functions are well known in the art and form no part of the present invention, wherefore it is believed unnecessary to describe them in detail here.

The headstock of the machine is indicated generally upon Fig. l by the character 80, and in- .cludes the gears necessary to drive at selective speeds the hollow spindle 3|. The spindle at its inner end may be furnished with a chuck 32 to firmly grip and rotate a work-piece A which extends within the bore of the spindle. Chuck 32 may be of any approved type. although as shown in Fig. l by way of example, it may be a conventional chuck operated by fluid pressure conveyed to an operating cylinder 34A by means of the supply pipe 34 and controlled by means of a valve 35. The work-piece on occasion may project outwardly beyond the headstock as indicated upon Fig. 13, in which case it may be desirable to furnish a second chuck 33 applied to the machine at the outer end of the hollow spindle. Chuck 33, which is applied only when the workpiece is very long and extends well to the left of the headstock, is here shown as one manually operated through the agency of a squared operating shaft 33A. Chuck 32B may be similarly operated. Chucks operated by pressure of air or liquid and chucks which are mechanically operated, are well known in the art wherefore they are illustrated only generally upon the accompanying drawings,

The several turning and forming tools are indicated by the characters 36 and 31, and these are securely mounted upon a turret 38 carried by the tool slide '2 l the turret being operative to present any one of several tools to the work-piece. If desired, the carriage may be provided with a plurality of turrets, or with tools arranged to engage the work-piece from the rear, as well as at the front of the carriage. As will be noted by referring to Fig. l, the turning and forming of the work-piece are performed by the turret tools at a location close to the chuck 32, so that chatter is eliminated irrespectiveof the depth to which,

the tools enter the work-piece. The turret is rotatable upon the cross feed slide to present the different tools to the work, as will be understood. Grooves cut in the work-piece by the tools, are indicated at 39.

In performing the method of the present invention, the reduced leading end 40 of the workpiece is gripped by means of a chuck 4| mounted upon the inner" end of the tailstock spindle 42, the chuck and spindle being rotatable with the work-piece. This chuck may be of any approved type, although as illustrated herein by way of example, it is operated by means of air or liquid under pressure fed thereto by a supply line or pipe 43 and controlled by means of a suitable valve 44. A pipe 45 conveys the fluid under pressure to a coupling 46 at the rear of the spindle, and from this coupling the fluid under pressure is conveyed to a cylinder Ml embracing a piston which actuates the chuck ll. The fluid pressure feed line 43, or some part thereof, preferably is made flexible to permit sliding of the tailstock lengthwise ofv the bed of the machine. Sliding movement of the tailstock maybe effected in any suitable manner, as by means of a hand wheel 4'! arranged to rotate a miter gear 48 which is in constant mesh with a second miter gear 49 that threadedly engages a longitudinal screw shaft 50 extending lengthwise of the machine bed. Screw shaft 50 may be a stationary shaft for the purposes of the present invention, although in some instances this shaft may be power rotated by mechanism located upon the bed of the machine for power shifting of the tailstock. Throughout the following description, it will be assumed that screw shaft 50 is a normally stationary part. Obvious equivalents for movement of the tailstock would be a rack and pinion arrangement, or means in the form of a pneumatic or hydraulic cylinder and piston constructed to afford the length of stroke required for maximum travel of the tailstock. These equivalent devices and others of common design are contemplated within the scope of the disclosure, as they are well known and obviously adaptable for shifting the tailstock as required.

The tailstock comprises the spindle housing 18,

and a separate tailstock carriage or base 5| upon which the spindle housing is guided for sliding movement by means of the dovetail 52. By means of a suitable clamp or binder mechanism, the spindle housing may be firmly fixed relative to the carriage or base. In the example illustrated, the binding or clamping means may be in the form of a shaft 53 extending transversely of the spindle housing for rotation within the bore 54. One end Oif shaft 53 may carry a binder or clamp lever 55 adapted to apply force at one side of the spindle housing, while the opposed threaded end 56 of the shaft threadedly engages a large clamp block 51 disposed along the opposite side of the spindle housing. Clamp block 57 is held against rotation in any suitable manner, and it will be noted that the action of the binder is to pull both sides of the spindle housing toward the dovetail, with spreading of the clamping force over a substantial area. This construction prevents undue distortion of the parts, and ensures efiicient repeated clamping over a long period of time without injury to the dovetail guide. Release of the clamp or binder mechanism by means .of lever 55 enables the tailstock housing to be with a plurality of clamping nuts 58 which are accessible at opposite sides :of the "carriage to tightly draw up one or more clamp bars 59 in which the lower ends of the clamp screws or bolts 60 are anchored. Tightening of the clamp nuts the dovetail guides 52, relative to the base :or carriage without disturbing a predetermined seti ting of the latter upon the bed of the machine.

In accordance with the present .invention, it

.is desirable that the tailstock spindle housing be made quickly retractable lengthwise of the base or carriage 5|, through a succession of steps, the steps being spaced apart predetermined distances in conformity with predetermined tool operations to be imposed upon the work-piece. Accordingly, it is desirable that a pattern be established and applied to the tailstock structure for predetermining the shifting movements of the tailstock, its chuck M, and the work-piece gripped by said chuck. That is to say, the method contemplates drawing the work-piece through the hollow spindle of the headstock and past the tools, with a succession of steps or movements dependent upon the locations at which the work-piece is to be machined.

For accomplishing this purpose, there is provided a stop bar 52 notched or otherwise provided with a series of abutments 63 formedat the upper edge 64 of the bar. Since the stop bar is in reality a pattern or template, it will in every instance be notched to suit a particular job. In the exemplification illustrated, the distance between successive notches or abutments in the upperedge of bar 62 are spaced apart in correspondency with the distance between the grooves to be formed in the work-piece, as illustrated at 39-49 of Fig. 1. use, is fixed to one side of the tailstock carriage or base 5!, with its edge 64 uppermost and in substantial parallelism with the bed of the machine. The notches or abutments are adapted to be engaged by a plunger 65 carriedby the tailstock spindle housing, so that when the plunger is in engagement with any one of the abutments of the stop bar, retraction of the tailstock housing away from the headstock will be definitely precluded. Thus, the plunger-5E may be dropped .into the various notches in succession, to limit the extent of withdrawal of the work-piece from the hollow spindle of the headstock, and the withdrawal steps or movements will be determined by the distance between successive notches or abutments 63 of the stop bar. Referring to Fig. 2, by way of example, it will be seen that the tailstock is locked by plunger 65, at the second last notch of the stop bar, work having been performed upon the work-piece A at each of the five preceding notches or abutments to the left .of the plunger. Since there isbut one additional notch at the right of the plunger, it is evident that only one more operation upon the work-piece is required in order to meet the specifications. Therefore, upon completion of the operation being performed while the plunger-is in thesec- 0nd last notch of the stop bar, the operator of the machine will lift the plunger momentarily, :move the tailstock to thei'right until the plunger The bar 62, when the machine is in lit.

seats within the lastznotch or abutment 63, and

"then clamp the tailstock tothe carriage or base :51 preparatory to performing the last machining :operation upon the work-piece. As long as the said machining operation is in progress as the result of automatic ror manual carriage and tool movements, the :tailstock will remain at the position determined by one of the abutments or notchese63.

The stop bar may be mounted upon the tail- :stock base or carriageiin'any suitable manner. As disclosed herein by way of example, the stop bar 62 provided with thenecessary notches or abut- 'ments, is laid fiatwise against a seat 66 formed at oneside of the carriage or base, and may be held inplace by means of a-series of bolts or other fasteners .61. To provide for slight longitudinal adjustment, the bolts or fasteners may pass through-elongated slots .68 formed in the material of the stop bar. Micrometric longitudinal adjustments of the stop bar may be desired in some instances, and .in :such case it may be desirable to provideanadjusting screw-69 .in endwise abutment with one end of the stopbar, the screw being threaded through a stationary block in applied to the side of the tailstock carriage or base. The screw may be locked in adjusted positions by means of a nut or other expedient l l.

At the opposite or forward end of th stop bar, an end stop or abutment 12 may be furnished, if desired, for locating the tailstock and clutch 4| relative to the forward end .of its carriage *or base 5 I ,and consequentlylocating the work-piece initially relative to the cutting tools. This end stop preferably, though not necessarily, may be formed from a separate piece 13 fixed to the carriage by means of screws or bolts M which need not-be disturbed by application and removal of stop bar 62. For the details of plunger 65 and its supporting means, reference may be had to Figs. 2 and 3 wherein 14 indicates a housing for the plunger, said housing being provided with a vertical bore or way 15 to accommodate the plunger and permit its shifting vertically into and from the notches of the stop bar. The plunger may be lifted manually by means of a handle or finger piece '16, theinner end of which has suitable connection with the plunger, as by means of a ring .or collar 11 surrounding a reduced portion of the plunger. The plunger preferably is non-rotatable in the bore 55, and ring 11 has limited rotational movement relative to the plunger, so that the lifter l6 may be elevated manually andthereafter thrown over slightly into a bayonet slot .18 formed at the upper end of the vertical slot 19 in the side of housing it. By means of the bayonet slot or latch, the plunger .may be retained .in an elevated position above the stop bar, so as to be inoperative to limit shiftinglmovements of the tailstock whenever free tailstock movements are necessary or desirable. When using the stop bar, however, as a means .to automatically position th work-piece relative to the cutting tools, the lifter 16 is to be slid in bar between successive abutments. The plunger may be forced against the upper edge of thestop 'barby means of alspring .80, if desired, the spring being compressed between the upper end of the plunger .and the lower face ofa screw 8| threaded into the upperend o'fthe plungerbore;

From the foregoing, it will be understood that successive shifting movements of the tailsto'el:

:spindle' housing to theright, is determined by the location of the notches or abutments 63 upon the stop bar 62.

1 spindle housing to the left may be limited by the forward abutment or stop 12. Movements in either direction, of course, may be precluded by tightening the binder clamp by means of lever 55.

The tailstock of the invention preferably is furnished with a guard to prevent an accumulation of chips and other foreign substances upon the screw shaft 50 and other vital parts of the tailstock assembly that require protection against scoring and premature Wear. The chip guard as herein disclosed comprises a flexible curtain which may be in the form of a band or ribbon of sheet bronze, steel, or other material. The upper reach of the curtain or band is indicated at 83, and will be seen to rest upon opposed parallel ledges 84 formed upon the upper face of the tailstock carriage, between the dovetails 52. The side edges of the curtain fit snugly within the confines of the ledges, so that foreign substance may not enter beneath the curtain at its opposite side edges, as the curtain travels lengthwise in contact with the surfaces 84.

The curtain has a free end 85 which is anchored to the slidable tailstock spindle housing in any suitable manner, as by means of rounded squeeze blocks 86 between which the curtain material is clamped by means of screws or other fasteners 81. The edges of the squeeze blocks are curved or rounded as indicated, to prevent sharply bending the material of the curtain, and thereby possibly weakening same.

At the extreme forward end of the tailstock carriage or base a pair of rotatable rollers 88 and 89 provides means for guiding the curtain downwardly then rearwardly, so that the lower reach 90 will be directed to the rear end of the carriage or base, where a third roller 9! furnishes the necessary support at that location. From roller 9i, the curtain may pass over additional rollers 92 and 93, and from the latter it extends forwardly to a squeeze block or anchorage 94 provided at the rear end of the slidable tailstock spindle housing. Between the anchorage 94 and the roller 93, the curtain 83 rests upon ledges similar to those indicated at 84 of Fig. 3, and may slide thereon as the spindle housing is shifted lengthwise of the tailstock base or carriage 5!.

Since the slidable tailstock spindle housing may at times be moved to an extreme position toward the headstock of the machine, it may overhang the forward end of the carriage or base at roller 88, and in the overhung position it is quite possible that the squeeze blocks 86 may be disposed to the left of roller 88. It may readily be appreciated that under such circumstances the curtain 84 may have to lengthen, and for this reason a compensator is provided in the form of a swinging tension arm locatedat the extreme right hand end of the base or carriage. The tensioning means may be in the form of an end plate 95 securely fixed to the rear of the carriage or base, said plate carrying a rearwardly extended arm 96 having a journal 91 for swingingly supporting a depending tensioning arm 98. The tensioning arm carries the roller 92, and is normally urged into counterclockwise rotation about its pivot shaft 99 in any suitable manner, as by means of a counterweight I00 which is adjustable along a counterbalance rod or arm lill. As will be readily appreciated, the yielding tension established by means of the counterweight, might alternatively be obtained with the use of a suitable spring or other equivalent means. It will be understood from the foregoing, that the flexible curtain will always be maintained in a taut condition by means of the tensioning mechanism located at the rear end of the tailstock carriage or base. Rollers 9| and 93 are rotatably mounted upon the tailstock carriage or base 51, whereas roller 92 is applied to the swinging end of the tensioning arm 98. When the slidable spindle housing is moved to the left to such an extent that the squeeze blocks 86-86 pass beyond the roller 88, curtain 83 will be so extended as to draw the roller 92 toward the end plate 95, in opposition to the yielding resistance of the tensioning means including the weight 199. Curtain 83 may be constructed of any suitable material having the necessary flexibility and durability to withstand wear imposed by movements of the tailstock spindle housing. It will necessarily be non-porous or impermeable to such extent as to preclude chips and other foreign materials from reaching the screw shaft and such other operating mechanism as is located beneath the spindle housing [8.

Figs. 4 to 12 inclusive represent in chronological order, the principal steps employed in the present method of fabricating a shaft which has numerous changes of contour, utilizing the machine of Figs. 1, 2 and 3. By Way of example, and without limiting the invention thereto, the following explanation is given to indicate the method steps and operations which are typical in the production of a large cam shaft, such as may be used in Diesel engines or the like.

Referring to Fig. 4, the work-piece A in rod or bar form has been loaded into the hollow spindle and projects through chuck 32 toward the chuck 4|. Chuck M at this time does not grip the work-piece, but is used merely as a pusher to properly locate the work-piece relative to tool 36, the chuck 32 being released meanwhile. Stop 12 initially determines the position of the Work-piece relative to the tools, by limiting the movement of the tailstock toward the headstock. This stop accordingly is to be fashioned or located to conform with the work-piece specifications, as in the case of the stop bar notches previously described. Once the workpiece has been initially located as stated, the assembly I8 is retracted to the Fig. 5 position, and chuck 32 is then actuated to grip and rotate the work-piece. Fig. 5 shows the first forming out being made by tool 36 close to chuck 32, to produce a reduced end upon the work-piece.

In Fig. 6, a second cut is being completed by the forming tool, likewise in close proximity to the chuck. Both of these forming operations may be performed without use of the tailstock, which is shown standing at rest in spaced relationship to the work-piece.

In the illustration of Fig. 7, the tool has been withdrawn from the Work-piece upon completion of its forming operation, and the tailstock spindle housing has been moved to the left along its carriage or base, to an extent necessary for subjecting the reduced end of the work-piece to the grip of the tailstock chuck 4!. With the chuck 4| gripping the end of the work-piece, and the grip of chuck 32 released, the tailstock housing is moved to the right until its plunger 651 drops into and engages the first notch or abutment 63 beyond the end stop'l2', thereby-- to=exactly position the work-piece 'relativeto turret and chuck 3-2' will be released, and the plunger 65' momentarily lifted as previously explained, to

permit shifting movement of the tailstock to the third notch or abutment of stop bar 62, which results in repositioning thework-piece so that tool 36 may perform the forming operation il-' lustrated by Fig. 9. As will be understood, the tailstock and the chucks will'be firmly set immediately prior to engagement of tool 36 with the work-piece.

Following the operation depicted by Fig. 9, the entire procedure may be repeated to complete another forming operation as at I02, and when this operation is completed the tailstock may be moved further to the right, upon release of chuck 32, to position the work-piece so that" the operation indicated at I03 may be performedby tool 31. It should be noted'that the lineal extent of operation I03 corresponds to the distance between notches or abutments H35 of the stop bar. The distances between notches or abutments of the stop bar, as previously explained, are established by the specifications to which the work-piece shall be turned and formed.

The illustration of Fig. '11 indicates an operation being performed subsequently to operation I03, it being noted that the tailstock has been moved tothe right a distance of one additional notch or abutment beyond I05.

As shown in Fig. 12, the last operation upon the work-piece is being performed, the plunger 65 having been lodged in the last notch of the stop bar. If the work-piece called for an additional forming operation similar to I02 of Fig. 10, the stop bar of Fig. 12 would carry an additional notch or abutment to the right of plunger 65, and from-this it will be understood that the stop bar might be of any length, and provided with any given number of notches or abutments corresponding with the number of machining operations to be performed upon the work-piece.

It will be noted by referring to Fig. 12, thatv the work-piece has been withdrawn from the hollow spindle of the headstock, to a point at which its trailing end IDS is quite close to the chuck 32. The work-piece obviously might be withdrawn even farther, if desired, without removing it from the grip of the headstock chuck 32, so that it becomes evident that turning and forming operations may be performed upon the work-piece practically to the very end I06. It may be appreciated, moreover, that the repetition of steps depicted by Figs. 4 to 12 inclusive may be continued limited only by the length of the machine bed and the travel of the tailstock in a direction away from the headstock chuck of the machine. The stop bar 62, of course, can be made in any length, and provided with any Hi l and number of notches'or abutments corresponding" to the specifications of the work-piece to be machined.

From all of the foregoing, it should readily be apparent that-the turret-may carry any required number of forming and turning tools, and that theywill always engage the work-piece at a location close to the headstock chuck 32;

Whenever the tailstock is shifted for presentingnew sections of the work-piece to the tools,

chuck 3-2 or any additional chucks such as. 33: carried by the headstock spindle will be released, as the tailstock chuckretains its grip upon the work-piece to withdraw the latter through the.

-1 hollow spindle of the headstock. The extent of withdrawal, as previously explained, is determined solely by the relative spacings of the stop.

bar notches or abutments. The advancing, retracting, and longitudinal movements of thetools relative to the workpiece may be performed either manually or automatically, as may be desired, or within'the capabilities of theautomatic cross feed and length feed control mechanisms of the machine. Application and removal ofthe work-piece to and from the machine may be eifected by means of a hoist or other conventional expedient, as will be evident in the light of the foregoing description.

As will be manifest to those skilled inthe art to which the invention appertains, various modificationsand changes in structural details of the parts and mechanisms herein disclosed may spindle, rather than at the exit end thereof, to

perform the function of successively positioning the work-piece relative to the tool means, it might not properly be'regarded as a tailstock within the commonly accepted meaning of the- 'term. The misnomer might apply also should chuck M be power rotated by means of a motor and thereby caused to rotate the work-piece, this being a perfectly feasible proposition as will be understood. For the reasons stated, therefore, the

part or assembly herein referred to for convenience of description as a tailstock, might not under all circumstances be properly classed as a tailstock within the strict definition of the term, and this fact is to be taken into account when construing the claim terminology.

What is claimed is:

1. A machine tool comprising in combination, a rotary chuck having an opening for the reception of an elongated workpiece to be machined at predetermined spaced areas along the length thereof, said chuck including releasable gripping means to enforce rotation of the workpiece with the chuck while precluding longitudinal shifting of the workpiece, tool means located in close proximity to the chuck and operative to shape the rotating workpiece, a workpiece positioning support shiftable toward and from the chuck and including a second rotary chuck in axial alignment with the workpiece, releasable gripping means on the second chuck for grasping an advancing end of the workpiece to move the latter through the first chuck when released, said second chuck having a closed end for abutting an end of the workpiece, and stop means for successively limiting retractileshifting movements of said positioning support, constituting a bar provided with abutments spaced apart in correspondency with specified spacings between areas of the workpiece to be machined, a cooperative plunger to engage the abutments, and means mounting the aforesaid constituents of the stop means, one upon the workpiece positioning support and the other upon a relatively stationary part of the machine.

2. A machine tool comprising in combination, a rotary chuck having an opening for the reception of an elongated workpiece to be machined at predetermined spaced areas along the length thereof, said chuck including releasable gripping means to enforce rotation of the workpiece with the chuck while precluding longitudinal shifting of the workpiece, tool means located in close proximity to the chuck and operative to shape the rotating workpiece, a workpiece positioning support shiftable toward and from the chuck and including a second rotary chuck in axial alignment with the workpiece, releasable gripping means on the second chuck for grasping an advancing end of the workpiece to move the latter through the first chuck when released, said second chuck having a closed end for abutting an end of the workpiece, and stop means for successively limiting retractile shifting movements of said support, constituting a bar provided with abutments spaced apart in correspondency with specified spacings between areas of the workpiece to be machined, a cooperative plunger to engage the abutments, and means mounting the aforesaid constituents of the stop means, one upon the workpiece positioning support and the other upon a relatively stationary part of the machine, the plunger including means for selectively disengaging it from the abutments.

3. A machine tool comprising in combination,

a rotary chuck having an opening for the receprotating workpiece, a tailstock shiitable toward and from the chuck and including a second rotary chuck in axial alignment with the workpiece, reieasable gripping means on the second chuck for grasping an advancing end of the workpiece to move the latter through the first chuck when released, said second chuck having a closed end for abutting an end of the workpiece, and stop means for successively limiting retractile shifting movements of the tailstock, constituting a bar provided with abutments spaced apart in correspondency with specified spacings between areas of the workpiece to be machined, a cooperative plunger to engage the abutments, means mounting the aforesaid constituents of the stop means, one upon the shiftable tailstock and the other upon a relatively stationary part of the machine, and means to adjustably shift one constituent of the stop means lengthwise of the workpiece.

4. A machine tool comprising in combination, a rotary chuck having an opening for the reception of an elongated workpiece to be machined at predetermined spaced areas along the length thereof, -said chuck including releasable gripping means to enforce rotation of the workpiece with the chuck while precluding longitudinal shifting of the workpiece, tool means located in close proximity to the chuck and operative to shape the rotating workpiece, a tailstock shiftable toward and from the chuck and including a second rotary chuck in axial alignment with the workpiece, releasable gripping means on the second chuck for grasping an advancing end of the workpiece to move the latter through the first chuck when released, said second chuck having a closed end for abutting an end of the workpiece, a normally stationary carriage including means to shiftably support the tailstock, a bar fixed to the carriage and having abutments thereon spaced apart in correspondency with specified spacings between areas of the workpiece to be machined, and a catch mounted on the shiftable tailstock to releasably engage the abutments of the bar in succession as the tailstock is moved to draw the workpiece through the first mentioned chuck and past the tool means.

FRANK A. FRITZSCH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 490,863 Conradson Jan. 31, 1893 848,578 Thelin Mar. 26, 1907 932,394 Johnson Aug. 24, 1909 945,979 Norton Jan. 11, 1910 1,338,742 Lofton May 4, 1920 1,664,757 Randolph Apr, 3, 1928 1,895,122 Benedict Jan. 24, 1933 1,907,961 Guillet May 9, 1933 1,981,263 Croft Nov. 20, 1934 2,416,612 Cavanagh Feb. 25, 1947 2,417,132 Schreiber Mar. 11, 1947 FOREIGN PATENTS Number Country Date 487,590 Great Britain June 22, 1938 1 559,444 Great Britain Feb. 18, 1944

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