US2889731A - Tail stock spindle - Google Patents

Description

June 9, 1959 a. P. KARLE 8 3 TAIL STOCK SPINDLE 2 Sheets-Sheet 1 Filed May 19, 1955 FIG. 6

i INVENTOR GEORGE P. KARLE ATTORNEY June 9, 1959 G. P. KARLE TAIL STOCK SPINDLE 2 Sheets-Sheet 2 Filed May 19, 1955 m NN INVENTOR GEORGE. P. KARLE ATTORNEY TAIL STOCK SHNDLE George P. Karla, Oil City, P-a.

Application May 19, 1955, Serial No. 509,480

1 Claim. (Cl. 8231) This invention relates to a tail stock spindle locking means which includes a hand operated safety device which may be integral with or attached to a tail stock on a metal spinning machine. The tail stock spindle locking means of the invention may be used with a wood turning lathe, a metal turning lathe and other turning machines, but it is particularly adapted for use with hand operated metal spinning machines and metal turning lathes.

In most turning machines such as metal turning lathes and wood turning lathes and the like a wheel and screw actuated tail stock spindle is used to hold the work from a dead center against the live center moved by the tuming device of the machine. In the hand wheel and screw actuated device the spindle is moved back and forth by the wheel and screw to properly center and frictionally hold the work in the machine. The back and forth movement of the tail stock spindle in the present invention is carried out by hand, and the spindle is locked by :means of locking means which holds the spindle end against the work to center the work against the live center for proper working and turning operations.

Thus, in accordance with the invention the screw and hand wheel are wholly eliminated without any sacrifice in the efficiency of operation or in the adaptability of the metal spinning machine to handle a great variety of spinning operations.

Prior art slide devices have also been suggested which are combined with wheel and screw arrangements so that the locking pressure exerted from the dead center against the work is the result of the wheel and screw rather than the result of the pressure of the spring slide against the work.

The use of the hand wheel and screw require the exercise of judgement by the operator, a judgement based upon experience and a judgement usually lacking in the unskilled. If the hand wheel is too loose the work may fly out and seriously injure or incapacitate the operator. If the work is too tight the work is damaged and the turning operation is to no avail. In the device of the invention the adjustment is automatic by virtue of the safety locking construction. Positive and safe engagement of the Work is assured regardless of the training and ex perience of the operator. This factor alone is one which is of importance in promoting the acceptance of the machine which has hitherto considered as adaptable only for use in industrial establishments under skilled supervision and in the hands of skilled operators. Accomplishing this desirable objective in the absence of the use of complicated and expensive equipment is an object of the invention.

The tail stock locking means in the present invention eliminates this unpredictable factor of judgement. In combination with the feature of the horizontal adjustability of the tail stock spindle handle, there is the mechanical cooperation of the locking means for the tail stock spindle, which permits precise control within a high degree of accuracy of the forward movement of the tail stock spindle and as a result thereof, the forward pressure otthe tail stock spindle ag inst the work.

There is utilized a locking slot or recess in the tail stock spindle locking means of the present invention which serves the purpose of receiving the handle member for locking the handle of the spindle in the slot. By locking the handle tightly in the slot, any undesired spindle movement is effectively prevented during the turning operation of the machine and the tail stock spindle cannot he accidentally moved in a backward direction to release the holding pressure exerted against the rapidly revolving blank. There is only one position for locking which requires that the'pin be retractable across the slot. The retractable pin is embedded in the locking means or plate. The pin is fitted with a spring to press the forward end of the pin securely against the opposite face of the slot and thereby securely lock the handle member of the spindle in the slot.

The adjustment of the pressure by the tail stock spindle against the work is controlled below a maximum pressure limit in accordance with the invention in contrast with the lack of control for maximum pressure exerted by the screw and hand wheel devices of the prior art. This provides a new safety advantage which is of importance in the turning of heavier guages of metal and which ordinarily introduce a risk in the usual spinning operations. Although this latter advantage is: not too apparent when skilled operators are using the metal spinning machine, it is of considerable importance in the training of unskilled personnel who lack the necessary judgement to gauge the ultimate effects of the screw and hand wheel adjustment.

By a simple manual adjustment of the handle in a recess in the tail stock spindle, the spindle is made ready for its locking position.

The locking means of the invention insures that there will be no longitudinal movement of the tail stock in the locked position, and holds the work securely against the turning form at the headstock of the turning or spinning machine.

By virtue of the positive safety action of the springfitted locking device embedded in the locking means, the locking operation automatically brings the work into proper alignment and maintains the proper pressure relationship to substantially obviate any possibility of unintentional accident during operation by unskilled personnel.

An important safety feature of the locking means comprises the spring-fitted safety locking device embedded in the locking means provided with a locking pin which projectsinto the recess for the handle, the pin being formed with a pull button at the other end so as to detachably secure the handle member for firm connection with the tail stock spindle.

The locking means in combination with the handle means for the ordinary tail stock spindle serves to control the positive pressure of the ordinary tail stock spindle at the headstock end of the machine in a new and improved manner.

The handle connection to the tail stock spindle locked in the recess of the locking means by the spring fitted pin embedded in the locking means is prevented from moving backwards because the locking means is made fast to the tail stock. The handle may be pulled out of the recess by merely retracting the spring fitted locking pin, and the spindle is retracted from the work by sim ply moving the handle back away from the headstock. Accordingly, the locking means of the invention permits easy assembly and disassembly of the work by even un skilled personnel.

The development of a safe and economical locking means is of great importance in developing portable spinning machines for home and for educational use such as for the training and education of unskilled persons whether in industrial art programs or in vocational training programs, in home study programs and in industrial training programs. It is of particular importance that the high speed machiney be provided with suitable safety equipment to prevent mishap during the critical early stages of education. This purpose is achieved in a new and highly satisfactory manner in accordance with the present invention.

It was hitherto thought that spring slide spindle mechanism would be too unsafe for use by unskilled operators due to the tendency of the spindle to retract in a backwards direction to cause the work to fly out of the machine at high turning velocities which would subject the operator to great danger. The hand wheel and screw were preferred for safety reasons, although their use provided difiiculties in the training of unskilled personnel. The present locking construction provides a novel and highly useful solution to the problems of avoiding the training difliculty with the wheel and screw device and eliminating the risk of injury to the unskilled operator during metal spinning operations.

Accordingly, an object of the invention is to eliminate dilficulties during the training and education of unskilled personnel and to provide suitably safety devices to facilitate the use of metal spinning lathes in educational training programs.

A further object of the invention is to provide a selfcontained locking means suitable for attachment to ordinary metal spinning machines or lathes in lieu of the screw and hand wheel device for bringing the tailstock spindle into frictional holding engagement against the work at the headstock during turning operations.

A further object of the invention is to provide an adjustable means for controlling the pressure of the tail stock spindle against the work in metal spinning operation which in turn improve the flexibility of small turning machines in safely handling heavier gauges of metal.

Other and further objects and advantages of the present invention will appear from the more detailed description set forth below, it being understood that such more detailed description is given by way of illustration and explanation only, and not by way of limitation, since various changes therein may be made by those skilled in the art without departing from the scope and spirit of the present invention.

In connection with the more detailed description, there is shown in the accompanying drawings, in

Fig. 1, a side elevational view showing the operative relationship of the tail stock spindle locking means to the tail stock of a metal spinning machine; in

Fig. 2, a. top View of the construction shown in Fig. l to which are added conventional elements used in spinning operations; in

Fig. 3, a sectional view taken along line 33 of Fig. 2; in

Fig. 4, a fragmentary top view as in Fig. 2 showing some of the details of the locking means of'the invention.

Fig. 5, a sectional view along line 5--'5 of Fig. 4.

Fig. 6, a fragmentary top view of another embodiment of the locking means of the invention; in

Fig. 7, a fragmentary vertical view partly in section of another embodiment of the locking means of the invention; and in Fig. 8, a vertical elevation of a modification of the spindle handle connection in accordance with the invention.

Fig. 9, a vertical elevation of another modification of the spindle handle correction.

In Figs. 1 and 2, the operative relationship of the tail stock spindle lockingmeans to the tail stock of a conventional metal spinning machine is shown. In Fig. 7 the adaptation of the tail stock is shown which includes the safety locking means of the invention as part of the tail stock casting. The spinning machine is mounted on table 10 and includes a suitable electrically operated motor 11, gear reduction means 12, and the base mount- 4 ing 18 for the tail stock 1 and head stock of the machine.

The conventional spinning machine is fitted with usual chuck 14 at the head stock end. (Fig. 1.) The head stock end is fixed in the longitudinal direction in rela tion to the tail stock 1 which is movable, the latter being slidably mounted on its separate lathe type bed 15, which is adjustable in the longitudinal direction within an accuracy of 1/1000 to 1/ 10,000 of an inch, if desired. The locking bolt 15a fixes the tail stock in the bed.

As shown in Fig. 2 the metal blank 17 which is being spun on the machine by the operator is held against the chuck 14, the live center, by a conventional back block assembly 16, 16a and 16b which includes the usual ball bearing mounted back block body 16a and the standard taper front fitting 16b and back fitting 16a, each fitting in frictional engagement with the frictional holding body 16d and the tail stock spindle 2, respectively.

The blank 17 is thus effectively held against the form 18 on chuck 14 by meansof the pressing force exerted by the end of the tail stock spindle 2 which presses statically against the intermediary rotatable back block 16, standard taper 16b and friction body 16d in contrast with the blank. The back block assembly 16, 16a and 16b moves forwards or rearwards as a unit with the tail stock spindle 2; for this movement there is provided a handle member 3 for suitable connection to the tail stock spindle which is locked in a fixed position in relation to the fixed tail stock by means of the safety locking means of the present invention.

In the ordinary spinning operation, the metal blank 17 may vary from very thin to heavier gauges of sheet metal such as'aluminum, stainless steel, sheet steel, etc. of the order of 0.01 inch thickness to about 0.1 inch thickness. The'work rotates at about 1800 to 3000 r.p.m. under an axial pressing force or thrust of about 20 pounds exerted against the rotating form 18. The tail stock spindle 2 is static whereas the internal ball bearing construction of the'member 16 permits the spindle to be static while the rotation of the friction body against the work is at the same velocity as the work 17 on turning form 18.

It has been found that the forward longitudinal displacement of the tail stock 2 by an amount of about l of an inch towards the head stock increases the spindle holding thrust acting against the work from a minimum safe value of about 25 pounds to a value of about 75 pounds. This latter value does no damage to the work and lessens the tendency of the work to fly out of the machine at high speed. This adjustment of the forward location of the fitted end of the spindle is readily effected by either moving the tail stock 1 forward on the bed 13 or by the structural adjusting features of the locking means as is shown in Figs. 1 and 2.

The locking means of the invention in combination with the handle member 3 which is securely fastened to the tail stock spindle 2 comprises the locking plate 5 having a recess 6 for the handle at one end of the plate where the handle projecting upwardly from the tail stock spindle 2 to be readily locked into position by the plate 5, the plate recess 6 and the locking pin 9 which holds the handle in the recess 6.

The spring fitted plate locking pin 9 projects at one end into the recess 6 and is urged into the locking position by spring 19. At its opposite end the spring 19 and pin 9 seats against the back end of the pin recess 21. The pin 9 is thus effectively seated in the plate 5, its forward movement being limited by projecting detent 22 in slideway 23 formed in the surface of plate 5. Adjacent the perpendicular inner front surface of recess 6, the detent 22 may be moved backwards in the slideway 23 to a handle releasing position at the opposite end of the slideway. The normal movement of the tail stock spindle'Z is forward towards the head stock when the blank17is locked to press against form 18. The tail stock spindle 2 is normally rotatable by hand in the unlocked position within the tail stock 1 and it is a natural movement to position handle member 3 at the operato'rs side of the Spinning machine against the rear end of the tail stock spindle locking plate 5 so that oblique surface 7 of the locking plate recess efiectively guides the handle into the recess along said surface 7 to retract plate locking pin 9 due to the thrusting movement against the tapered surface 9a of the pin 9. As soon as the handle 3 moves past the back surface of locking pin 9, spring 19 pushes the pin towards the rear end of the plate 5 and snaps the locking pin 9 into the position limited by detent 22 in slideway 23. The only movement required thus is to guide the handle and spindle by a hand movement into the recess along the oblique recess surface 7 and the tapering end 9a of the pin so that there is only one operative locked position which can be attained. The click or snap of detent 22 is positive assurance that the work is locked in place and is an important safety feature of the invention.

The forward adjustment of the tail stock spindle and as a consequence thereof the pressure or thrust against the work within predetermined safety limits is positively and precisely controlled for training purposes and for operations by unskilled personnel as a result of the construction and arrangement of the locking means for the tail stock spindle. In addition to the conventional means for control by adjusting the forward location of the tail stock 1 by moving the stock forward in the bed 13, the tail stock spindle handle 3 is securely attached to the tail stock in a variety of predetermined forward thrusting positions as is illustrated in Figs. 2, 7 and 8.

The handle 3 may be screwed, taper fit or otherwise suitably connected in corresponding handle recesses in the body of tail stock spindle 2, as in recess 24a, 24b, 24c, and 24d, which are shown in Fig. 2 or as in a recess 26 in a longitudinally adjustable set screw fitted collar 25 as shown in Fig. 8. The spacing between the fixed positions 24a through 24d is in accordance with predetermined spacings for standardized shaping operations. a variety of shaping operations are to be carried out on different forms these may be stages on forward movement during the shaping of the blank 17.

Accordingly, the successively locking stages position 24d, 24a, 24b, and 24a each provide the necessary safety factor for each this insures that the metal blank the live center of the machine.

The taper or angle of the oblique surface 7 of the locking plate recess 6 for the handle permits lateral limited movement of the handle 3 along surface 7 towards the pin 9 to take up the back thrust of the tail stock surface 7 affords the back edge of the handle. In addition, the depth of the recess 6 is adapted to provide for additionally increasing the thrust of the handle and spindle against the work; in terms of forward movemnet on the order of 3/ of an inch, the handle against the work of about 25 to 30 pounds as compared the threads may be omitted, if desired, and the handle being taken to insure sulficlently deep and tight fitting connection of the handle 3 in the spindle 2. Or, as shown in Fig. 8, a collar 25 may be mounted about the tail stock spindle 2 and the upper part of the collar provided with a suitable recessed connection to engage the tail stock spindle handle 3. In this embodiment the positions which correspond to the turning forms may be at 27a, 27b, 27c, 27d, and 27e. The setscrew 28 in collar 25 serves to lock the collar 25 against the spindle or into an appropriate recesses if desired. Usually, the set screw may simply be utilized with a solid standard tail stock spindle and a suflicient tightness of the connection is to be maintained 1n order that the connection be at least twice or three times the reaction pressure developed by the blank during the turning operation, to thereby hold the splndle tightly. In Fig. 9 the handle 3 is shown in a taper fit with the recesses 27a, 27b, 27c, 27d and 27e respectively.

The tail stock spindle and tail stock spindle handle are fabricated of high grade tool steel or equivalent materlal and are strong enough to be subjected to very large tension, flexure or impact forces without danger of bending, breaking or other failure. The usual requlrement 1s that the steel in the thickness of the material employed to /3 round stock for the handle or to 1% inch round stock for the spindle), be capable of being subjected to ten ton load under any of these conditions without undue deformation or failure. Although the spindle and handle are shown in the form of round, any other shape may be used if desired.

The shortening of the distance from the tail stock spindle to the handle lock provides for a stronger spindle connection and for improved transmission of thrust in proper alignment against the work in the machine. Accordingly, it is desirable that the tail stock spindle means and handle be in connection with each other at a short vertical distance apart. The etfective holding and locking means for the handle is displaced from the axis of rotation in the vertical direction by only a short distance and the assembly is squat and inflexible when locked rather than tall and flexible at the handle end. This condition is enocuntered in the tail stock of the usual turning machine construction so that the portable locking means attachment may be used, which is the embodiment of Figs. 1-6. The attachment is readily mounted by suitable bolts to the existing tail stock to provide a sturdy mechanical connection to the existing tail stock 1 modified only to receive fastening bolts 31 and 32.

It is not necessary, however, that the locking means be utilized as a separate locking plate for attachment to the body of the tail stock 2. As shown in Fig. 7, the locking means may be an extension 5a of the appropriate surface, the upper surface, of the tail stock 1, this extension being reformed during the casting of the tail stock and the extension fitted as shown in Figs. 4-6 with the spring fitted locking pin and recess for locking the handle member, in the same manner as in Fig. 2.

As an indication of the ease of operation and the high degree of safety which results from the locking means of the present invention, an attachment of the type as illustrated in Figs. 1 and 2 was bolted to the tail stock of a 12-inch spinning machine, and in actual classroom tests, a blindfolded student, 12 years of age had no difficulty in locking (safety blanking) a 15 inch spindle so as to properly center and lock the work in the machine under a thrust condition where the work couid not be driven out of the machine with a hammer. The same subject, blindfolded, by grasping the detent and pulling back the spring fitted safety pin, readily released the handle from its locked position to retract the spindle for the disassembly of the work.

Since the existing commercially available tail stock is already in accurate alignment for the proper centering of the work on the form, it is apparent that the use of the locking attachment of the invention cannot affect the accuracy of the alignment of the machine and provides assurance against even accidental rearward displacement such as is so commonly encountered in many of the wheel and screw type of tail stock spindle holding devices. The blindfolded boy, in the classroom test hears the automatic click or snap of the spring fitted pin 9 when the handle is pressed into the locked position, assuring him that the work is locked in place before the motor switch is pressed. The recess is so constructed in depth that the handle fits tightly against the bottom of the recess immediately after the click is heard.

Since no axial centering operation is required there is a safety advantage for unskilled personnel without any affect on the efiiciency or speed of operation.

If a failure in the locking operation were to occur, for example, by a failure of the spring, such failure is not only seen but it is evident by the silence, lack of snap, as well. Only elementary checking or inspection operations are necessary to insure that the safety locking means operates properly and a serious operational hazard is overcome.

As will be apparent from the embodiments illustrated in Figs. 4-7, the arrangement of the locking pin 9 may be on either side of the recess 6 for the handle. In Fig. 6, pin 9 provided with button 29 is fitted securely in the transverse recess 33 of plate 5, and is fitted with spring 19 urging the pin to the closed position. Button 29 is threaded to pin 9 and the button is fitted with auxiliary pin 31 fitting into its recess 34 in the plate, pin 31 keeping button 29 from working loose and preventing pin 9 from turning to thereby maintain surface 9A in proper locking and unlocking relation. Depending upon the thrust desired, the depth of recess 6 may be varied; such depth being sufficient to provide ready clearance for the handle 3 to its locked position behind the pin 9. The mechanical advantage offered by the inclination of the oblique surface 7 of recess 6 may likewise be adjusted for the holding thrust desired and in view of the gauge of the metal turning material employed.

Although the invention has been described with reference to a metal spinning machine, the locking device may also be used with other turning machines, such as wood turning lathes, metal turning lathes, reamers, etc. and particularly those machines which are fitted with an accurately aligned housing for an axially aligned spindle to engage a live work center at the motor driven end thereof. Although a horizontally movable spindle is illustrated, it is manifest that the spindle may be movable in a direction other than horizontal. While a. simple spring has been shown, compound springs may also be used for urging the pin to the locking position.

To aid in assembling and disassembling the spring fitted pin 9, a recess has been provided in the left hand position of plate 5, illustrated as recess 34 in Fig. 4 and the pin members slide through this recess. First spring 19..

is passed through, then pin 9 is slid into place to engage the spring. As shown in Fig. 5, the locking pin 22 for retractable pin 9 driven into the seating recess 9b of the pin locks the pin assembly into its operating position. In Fig. 6, pin 321 performs the same function although in a different mechanical arrangement as does pin 22 in Fig. 5. By pulling out or otherwise removing pins 22 or 31, the pin assembly is readily dismantled to withdraw the spring and pin.

In the embodiment shown in Fig. 6, separate plug 35 serves to secure the pin assembly in the recess therefor in plate 5. Plug 35 is externally threaded to be screwed in place in the correspondingly upper threaded recess therefore in the plate. Plug 35 serves as the end stop for spring 19 and the pin 9 passes through plug 35 to present its tapered end surface 9a in proper relationship for permitting the entry and snap locking of the handle member 3.

To assemble the pin and spring in the embodiment shown in Fig. 6, pin 9 is placed in recess 33, spring 19 is placed over the shank of pin 9, plug 35 is screwed in place, button 29 is screwed on the threaded end of pin 9 and the button aligned to plate locking pin 31 through the button into locking recess 34. The dismantling operation is simple. After removing pin 31, button 29 is unscrewed, plug 35 is removed and the spring and pin are withdrawn from the locking pin recess.

The accurate alignment of such turning machines is.

unimpaired by the locking device of the invention since the locking device does not affect the existing alignment. The extension of the housing to enclose the spindle locking means including the spring fitted locking pin for locking the handle extension from the spindle may be achieved either by modifying the existing housing or by attaching the detachable plate member as already described.

Particularly in standardized automatic turning operations which are becoming more widely used in machine forming operations, the locking means of the invention may be utilized with even heavy duty turning machinery to bring further advantages of safety to mass production operations, with no sacrifice in efficiency and at very little additional cost. The advantages in improved safety conditons amply justify the small expense in installing the devices of the present invention.

Accordingly, it will be appreciated that the elements of the invention may be modified in shape, design and form or through the use of equivalent elements known to one skilled in the art without altering the basic cooperating safety locking features while remaining within the scope of the invention as described and claimed.

What is claimed is:

A tail stock for a turning machine comprising a tail stock body piece having a cylindrical bore formed therein, a spindle fitted within the bore of said tail stock body piece which is slidable in said bore to permit axial movement and rotation, said spindle having a plurality of holes aligned transversely to its axis, an arm projecting outwardly from a hole in said spindle for moving said spindle, a plate secured to said tail stock body piece which is slotted adjacent an end of said tail stock body piece to define a recess, said recess being positioned to receive said arm upon rotation of said spindle and to hold said spindle against the work, the trailing end of said recess being forwardly inclined whereby rotation of said spindle for placing said arm in saidrecess at the trailing end thereof will cause said arm to slide against the inclined surface of said recess and thrust said spindle forwardly of said tail stock and locking means for retaining said arm within said recess including a spring biased locking pin slidably mounted in said plate to close the open end of said recess and hold said spindle securely against the work for turning operations.

References Cited in the file of this patent UNITED STATES PATENTS 258,582 Hyde May 30, 1882 504,633 Squires Sept. 5, 1893 660,821 Obermier Oct. 30, 1900 787,471 Russell Apr. 18, 1905 808,528 Finney et al Dec. 26, 1905 880,063 Beilfuss Feb. 25, 1908 1,005,538 Greaves Oct. 10, 1911 1,046,720 Barnes Dec. 10, 1912 1,192,733 Bennett July 25, 1916 1,357,362 Sundstrand Nov. 2, 1920 1,464,415 Fontana Aug. 7, 1923 1,823,642 Brown et al Sept. 15, 1931 1,907,961 Gu-illet May 9, 1933 1,968,721 Stewart July 31, 1934 2,201,274 Singer May 21, 1940 2,695,800 Soucy Nov. 30, 1954 FOREIGN PATENTS 2,173 Great Britain Sept. 3, 1863

Images