US2676507A - Device for automatically reproducing through the copying of templets - Google Patents

Description

April 27, 1954 R. LE BRUSQUE ETAL 2,676,

DEVICE FOR AUTOMATICALLY REPRODUCING THROUGH THE COPYING OF TEMPLETS 4 Sheets-Sheet 1 Filed Oct. 23, 1948 in N J 1% \N 42- M I I N N L3 N f 1 N W x ii INVENTORS Rene LeBrusqae BY Arr/mudarce/ lelm April 27, 1954 Filed Oct. 23, 1948 R. LE BRUSQUE DEVICE FOR AUTOMATICALLY REPRODUCING THROUGH THE COPYING OF TEMPLETS ETAL 4 Sheets-Sheet s 4 v L I .51 '50 xf m J6 I I =rlllllllll f V 31 w 33 INVENTORS F?ene Leflrusque d/l/ r e/LeLan M1 27, 1954 R. LE BRUSQUE ET'AL 2,676,507

DEVICE FOR AUTOMATICALLY REPRODUCING THROUGH THE COPYING OF TEMPLETS Filed Oct. 23. 1948 4 Sheets-Sheet 4 IN VEN TORS Rene LeBrusque Patented Apr. 27, 1954 DEVICE FOR AUTOMATICALLY REPRODUC- fig fgHROUGH THE COPYING 0F TEM- Ren Le Brusque and Armand Marcel Le Lan, Paris, France, assignors "to Societe Anonyme dite: Compagnie Generale deConstructions fle Locomotives .France '(Batignolles-Ghatillom Paris,

Application October23, 1948, Serial No.56,22\4

The present invention relates to copying lathes, and is particularly directed to .a device associated with a lathe for reproducing the form of a template incompletely automatic operations.

This invention particularly relates to copying .Ia-thes wherein the tool'carrier is moved in .two directions which are respectively parallel and at right angles to the axis of rotation of the work pieceand the longitudinal axis of the template, and an object of the invention is to provide a tracer mechanism .in association with a lathe of this description which permits the accurate reproductionof templates having steeply inclined shoulders thereon, such reproduction being achieved in a fullyautomatic manner and without any supervision .or manual control by an operator. Anotherobject is to providea tracing mecha-v nism for association witha lather-of the described.

character, wherein the movements of the tool in the direction at right angles .to the axis of rotation of the work piece are effected'by hydraulic actuation controlled through a suitable valve assembly, and wherein the valve assembly is manipulated. mechanically by the tracer mechas versal movements imparted thereto during the reproductionof slopes ranging in steepness up to. a predetermined value, for example, 760, and the reproduction of slopes of a steepness exceedin tha pre t rminedyalue is carried out in steps by imparting successive and alternatingj1ongitu dinal. and ,transversal movements to the crossslide.

'In accordance with ithe present invention, above objects, and other objects, features and advantages thereof appearing in the following de:

tailed description of an illustrative embodiment,-

are achieved by providing a copying'lathe having a cross-slide carrying-the cutting tool and movable longitudinally a1on-g a path iparallel tothe axis of rotation of the work piece and transversely at right angles'to that axis.- The fixed template and :COntIO]. the movements of the cross-slide in accordance with the shape of the template The itransversal movements of the cross-slide are effected by a hydraulic system which is controlled by-a suitable valve assembly. The tracer mechanism includes a tracing member which is mounted pivotally for movement about a first axis which ,is parallel to thelongitudinal movements of the cross-slide and a second axis which is perpendicular to the .planeof the transversal and longitudinal movements of the cross-slide. The tracing member is provided with a valve actuating finger which manipulates the valve assembly controlling the hydraulic system in response to pivoting of the tracing memher about the first axis. Eivoting of the tracing member about the second axis resiliently resisted and control of the valveassembly, during the reproduction .of slopes having less than a predetermined steepness, is effected only by pivoting of the tracing member-about the vfirstaxis. However, whenaslopeon the templateexceeding the predetermined steepness is encountered by the tracing member, the resultant force is suflicient topvercome the resilient resistance to pivoting .of the tracing member about the second axis and-the-finger-memberin pivoting about the second axis actuates a switch in an electriccir-s. cuit to open the-latter. The electric circuit ineludes a normally energized solenoid having a plunger which is spring urged, when the solenoidv is ,deenergized, a ainst the valve actuating finger to effect further rocking of the Jlatterabout the. first axis, thereby iurther manipulating the valve assembly of the hydraulic system actuating the cross-slide. The electric circuit further includes a magnetic clutch interposed in the lathe mechanism efiecting longitudinal movement of the cross-slide so that, when the electric circuit is opened, the clutch .is ole-energized and the longitudinal movement of the cross-slide is .momentarily halted. "Ihere'fore, when a slope of relatively great steepness is encountered on the template, the cross-slideis moved alternatelyand successively in the transversal and longitudinal directions and in .a step-.by-step manner to substantially reproduce the steep slope on the workpiecemountedinthelathe The foregoing features v.or characteristics of devices embodying the present invention will be apparent in the following detailed description of anillustrative embodiment, when the description is read in connection with the accompanying drawings which .formhapart hereof and wherein:

Fig. 1 is a top ,plan' view, partly broken away and in section, of a copying lathe incorporating tracing mechanism constructed in accordance with the present invention;

Fig. 2 is a vertical sectional view taken alon the line 2-2 of Fig. 1, but on an enlarged scale and showing the construction of the tracing mechanism;

Fig. 3 is a horizontal sectional view along the line 3-3 of Fig. 2;

Fig. 4 is a fragmentary plan view, partly broken away and in section and on an enlarged scale, of an assembly forming a part of the mechanism of Figs. 2 and 3; and

Fig. 5 is a diagrammatic representation of the related movements of the feeler mechanism and of the cutting tool in reproducing a shoulder of relatively great steepness on the fixed template.

Referring to the drawings in detail, and initially to Fig. 1 thereof, a copying lathe is there shown embodying tracing mechanism constructed in accordance with the present invention. The lathe, as usual, includes a chuck or face plate and a tailstock between which the work piece I is supported for rotation about its longitudinal axis. A carriage is slidable on the bed of the lathe for movement parallel to the axis of rotation of the work piece and such movement of the carriage is effected by the conventional worm screw. The drive for the worm screw includes a magnetic clutch 6 interposed between a belt and pulley transmission and the worm screw so that the latter is rotated, to effect longitudinal movement of the carriage, only when the clutch 6 is electrically energized. A cutting tool 8 is mounted upon a cross-slide l0 which is carried by the carriage and is movable relative to the latter at right angles to the axis of rotation of the work piece I. Such transversal movement of the cross-slide is eifected hydraulically by an arrangement which includes a piston 9 (Fig. 2) working in a cylinder 90 fixed to the carriage. The piston 9 extends axially from the cylinder 90 and is coupled, as at l2, to a connecting rod H (Figs. 1 and 2) which is secured to the crossslide Hi. It is apparent that the position of the piston 9 within its cylinder determines the position of the cutting tool 8 relative to the workpiece.

The purpose of the described lathe is to reproduce the contours of a template I on the work piece I, and the template I is accordingly mounted between suitable centers 2 and 3 with its longitudinal axis extending parallel to the axis of rotation of the work piece. In order to facili tate the mounting of the template, the centers 2 and 3 are preferably slidable in housings 2' and 3, respectively, which are movable along a bed or guide 4 fixed relative to the bed or frame of the associated lathe. The centers or points 2 and 3 are axially adjustable, to grip the template I therebetween, by manually adjustable screws 2" and 3", respectively. Thus, the centers 2 and 3 may be drawn apart to permit the removal or replacement of the template.

The tracing mechanism embodying the present invention is generally indicated by the reference numeral 1 and serves to control the transversal and longitudinal movements of the cutting tool 8 in accordance with the changing configuration of the template I as reproduction of the form of the template proceeds. In order to control the transversal movement of the crossslide l0, and hence .of the cutting tool, a valve assembly (Fig. 2) is associated with the piston 9 of the hydraulic system. This valve assembly taken includes a valve body or housing l3 mounted on a portion of piston 9 disposed outside of the cylinder 90. A valve member I4 is vertically reciprocatable within a suitable bore formed in the body 13 and projects upwardly from the latter. A spring I5 is disposed below valve member [4 to continuously urge the latter upwardly. A hydraulic fluid, under pressure, is supplied to the cylinder So at the opposite faces of the piston 9, as indicated by the arrows J and f, from a, suitable source (not shown). Since the area of the face 9a of piston 9 is greater than the area of the face 9b, the piston 9 will move toward the left, as viewed in Fig. 2, when the pressure of the hydraulic fluid at the opposite sides of the piston is the same. Such movement of the piston 9 causes the cross-slide ID to move transversely in the direction backing the tool 8 away from the work piece I. In order to control the relative pressures acting against the opposite faces 9a and 9b of the piston, a passage I3a is formed in the valve body l3 and communicates at one end through the piston 9 with the portion of the cylinder facing toward face So of the piston. The passage |3a opens into the bore accommodating valve member I4 and an exhaust passage l3b also opens into that bore at a location spaced axially from the passage I3a. The valve member [4 is formed with a reduced diameter portion Ma which more or less communicates the passage l3a with the exhaust passage 131), depending upon the position of the valve member I 4 within the body l3. The various parts are dimensioned so that the pressure acting against face 9a of the piston is sufliciently reduced to equalize the forces acting against the faces 9a and 9b when the valve member 14 is raised a predetermined distance to provide partial communication between the passages Ba and l3b. When the valve member I4 is raised more than the above mentioned predetermined distance, the increased communication between the passages l3a and l3b further decreases the pressure in the fluid acting against the face 9a so that the force acting against the face 91) is predominant and the piston 9 moves to the right, as viewed in Fig. 2, to displace the cross-slide Ill and the tool 8 in the direction moving the latter toward the work piece I. Thus, the position of valve member I4 within the valve body l3 determines the position and movements of the piston 9 and the cross-slide I 0.

In order to control the position of valve mem-. her I 4, the tracing mechanism I illustrated in Figs. 2, 3 and 4 includes a pair of spaced apart, transversely extending support arms 33 and 34 secured to the top of the valve body l3 and directed toward the fixed template I. A gimbal mountv is supportedby the free ends of arms 33' and 34 and includesa body 30 having trunnions 3| and 32 projecting from the sides thereof and received in suitable recesses formed in the confronting side surfaces of the support arms. Thus, the body 30 is rotatable about an axis l1 passing through the trunnions 3| and 32 parallel to the longitudinal axes of the template I and the work piece I. The body 30 is formed with a bore extending therethrough at right angles to the axis l! for rotatably accommodating an axle 35. Axial movement of the axle 35 relative to the body 30 is restrained by suitable-structure which may include a shoulder or rim 39 on the axle adapted to overlie the upper surface of the body 30 and a securi g disc-38 fixed to the lower. end of axle 35 below the under surface of body by a machine screw 40. :In order to reduce the frictional resistance to turning of axle .35

within the body 30, ball bearings 36 and 31 are disposed between the upper and .lower faces of the body 30, which are preferably bevelled, and the rim 39 and disc 38, respectively.

The axle has an upper portion above the rim 39 which supports a member4| intended to carry a tracing member 42 in a position to ride upon the surface of the template I- Themempber 4| is formed with a bore which receivesrthe accommodating the stem 43 so that a ball or detent disposed inthe tapped bore may engage the notch 44 and locked in "this position by a set screw 45 to prevent withdrawal of the stem '43 from the assembly. It will be noted that the longitudinalaxis of the tracing member 42 is disposed'substantially above the axis oi the trunnions '3l and 32 so that a force applied axially.

to member 42 in the direction toward the left, as

viewed in Fig. 2, causes counter-clockwiserocking of the member 4|, axle'35 and body 30 about the axis 11.

In order to translate such rocking movement of the member 4| into vertical displacement of the valve member I 4, a finger i6 extends from the member 4| in the direction opposite to the tracing member 42 and offset downwardly relative to the latter, and overlies the upper end of the valve member l4 projecting from fthe'body 13. 'The finger 16 preferably carries an abut ment |6a for engaging the upper end of valve member l4 so that, when the member 4| is rocked about axis I! in the counter-clockwise direction, as viewed in Fig. '2, the valve member |4 will be depressed against the :force of spring |.5 to further restrict communication between the passages .l'3a. and i317 and thereby cause movement of piston 9 toward the left, in the manner previously described. Further, it is apparent that, when the axial force is removed from the tracing member 42, the spring l5 raises valve member H to increase the communication be tween passages 13a and Bo thereby causing movement of piston .9 toward the right, as viewed in Fig. 2, and the upward movement of valve member l4 causes rocking of member 4| about axis. I! in the clockwise direction, .as viewed in Fig. .2. A .bo1t53 .is preferably threaded into the top surface .of the valve body 13 with its head overlying thefreeend portion olfinger It to proszide' anadjustahle-sstop forjlim'iting llllwardimove \ment of .t'hefinger 1.6. v

Ahousing 22 for the .tracingmechanism issu" ably secured on top of the valve body .|.3 and with the latter forms a .head which opens towardthe template I to permit the tracing member .42 to project therefrom. ,Ashaft .|.9 is journalled in the side walls of housing 22 .for rotation about an axis parallel .to the longitudinal axis of the template. .An arm 20 isfixed on shaft H by a .pin .or the like and overlies the finger 16. Thus, when theshaft 9 isrockedin the counterclockwise direction, as viewed in Fig. '2, the fires and :or arm 2.0] hears downwardly on linger .l'igto depress "thelatter and cause downward move;

ment ioi'wazlve member 4. .In order to permit manual rocking oi the shaft t9, ajhandle i8 is coupled toanendof the shaft I19 extending from the-housing 22, as in Fig. 3,, and .the handle l8 extends to alocation at which it can be conveniently manipulated by the operator of the machine. The separable coupling of .handle |8 to the shaft I9 is preferably achieved by a pin laeu'tending axially from the :handleatian eccentrio location and into a recess .or :notch 21a of a flanged sleeve 21 which is fixed to the shaft l9. Thus, the handle 8 may :be removed from the shaft l9 or assembled, as in Fig. 3, when a manual control desired.

In order to provide the previously mentioned step by step reproduction of slopes of a steepness exceeding a predetermined value, the tracing mechanism 1 includes the following structure, illustrated indetail in Fig. 4. A cantilever spring :mem'ber. .41 extends from the body 30 alongside the finger .I6 and bears against the latter to continuously urge the finger I6, member 4| and tracing member -42 to rotate in the counter-clockwise direction, as viewed in Fig. 4, about the axis of axle 35. The spring urged rotation of finger l6 about the axis of axle 35 is limited'by a stop 4-8, which may be formed by the head of a bolt extending from the body 30. A plunger 5| is axially slidable in a bearing '50 carried by the support arm 34 and .engages at one end the adjacent side face of the finger 16. A resilient element '52 is secured to the outside of support arm 34' and is engaged by the other end of the plunger 5|. A micro-switch 49 is mounted on top of the valve body l3 adjacent nricro-switch. The micro-switch 49 is of conventional construction and is arranged so 'that the contacts thereof are closed, when the actuating plunger ispermitted to project from the sw-itchhousing, and so that the-contacts are sep* arated to break the associated electrical circuit, when the'actuating plunger is depressed into the switch housing. Thus, when the finger i5 is in its normal position, shown in *full lines in Fig. '4, thecontacts of switch '49 are closed; and, when the finger 1-6 is rocked in the clockwise direction to the broken-line position of Fig. 4, the plunger 5| urges-the resilient element52 against th-e'actuating'p'lunger of the switch 49 to depress the last mentioned plunger and thereby separate the switch contacts.

seen in Fig. 2, a solenoid 2| is mounted on top of the housing 22 and includes a vertically movable core 23 which is positioned above the arm orjlever-2fl. Arspring 24"is-provided around the *lower' portion of the core '23 to yieldably urge thelatter downwardly against the arm 20, and suitable adjustable stop nuts 25 and '26' are tlnreaded onto "the upper portion of core '23 to limit such downward movement of the core; However, the solenoid 2] is arranged so that the core "23 held in an elevated and inoperative position (Fig. '2') against the action of the spring 24 when {the coil of the solenoid is electrically energized.

As seen diagrammatically in Fig. '1, the magnetic clutch i6 and the-solenoid 2| are electrically connected in parallel with each other and in series with the contacts of switch 49 across the lines of a suitable source of electric current.

I "Thus, solong as the contacts of the switch- 49 are. .clos.ed, the clutch .8 and the solenoid time continuously-energized, however, wherithe-cmi;

tacts of switch 49 are separated in response to rocking of the finger l6 about the axis of axle 35, both the solenoid 2| and the magnetic clutch 6 are simultaneously de-energized. It is preferable to provide an electrically actuated brake (not shown) of conventional construction in association with the driven part of the clutch 6 to instantly and automatically halt rotation of the driven part when the clutch is deenergized.

When the solenoid 2| is deenergized, the core 23 presses downwardly on the arm 20 which in turn depresses the finger It to displace the valve member |4 downwardly thereby interrupting communication between the passages |3a and |3b to cause'the piston 9 to move inthe direction displacing the tracing member 42 and the cutting tool 8 transversely away from the template I and the Work piece |,respectively. At the same time, the deenergization of the magnetic clutch 6 interrupts the drive of the worm screw causing longitudinal movement of the carriage with the cross-slide ii). Thus, when ever the contacts of switch 49 are separated, the longitudinal movement of the cutting tool ceases and the tool is moved transversely away from the work piece. a

The operation of the above described'device in reproducing the form of a template will now be described:

The template I and work piece I are mounted between the centers or points 2 and 3 and the chuck and tail plate of the lathe, respectively, with the tracing member 42 of the tracing mechanism and the cutting'tool 8 being positioned the same distance from the longitudinal axes of the template and work piece and with the carriage and cross-slide It being longitudinally positioned so that the tracing member 42 is adjacent the right hand end of the template, as viewed in Fig. 1. If the tracing'member 42- is initially spaced transversely from the template, no force will be exerted on the tracing member 42 and the valve member l4 will be moved upwardly by the spring |5 to provide the maximum communication between the passages I30; and

| 4, thereby decreasing communication between ner described above for interrupting the longipassages Na and |3b to equalize the forces acting on the opposite faces of the piston 9 and halt the transverse movement of the cross-slide It). It is to be understood that the lathe carriage and its cross-slide are longitudinally moved at a substantially continuous rate during normal operation of the copying lathe in the direction from right to left as viewed in Fig. 1. the tracing member 42 moves longitudinally along the surface of the template I. slope of a steepness less than a predetermined value is encountered on the template by the tracing member 42, the force acting on the member 42 in the direction transversal-with respect to the axis of the template is initially increaswl to cause further rocking of member 4| and finger |6 about the axis I! in the direction further depressing the valve member .|4. This further depression of valve member. l4 again decreases the em n q ii n betwe n, a e 1 a I 1 80 Thus,

When a h that the piston 9 and cross-slide |0"are displaced transversely to move the tool 8 transversely away from the axis of rotation of the vwork piece at a rate corresponding to the slope of the template then being reproduced. While the force acting on the tracing member 42 in the direction tend:- ing to produce rocking of the member4| and finger l6 about the axle 35 is increased when the tracing member encounters a slope on the template, the spring 41 (Fig. 4) is suflficiently strong to prevent rocking about the axle 35 so long as the slope does not exceed a predetermined steepness, for example, a steepness of 60". Therefore, for normal slopes on the template, the transverse movement of the cross-slide is controlled only by rocking of the tracing member 41, member 4| and finger IB about the axis l1.

However, when a slope exceeding the predetermined steepness is encountered by the tracing member 42 on the template a strong force is imposed on'the tracing member in the direction parallel to the longitudinal axis of the template, and the force of spring 41 is overcome so that the member 42, member 4| and finger l6 are rocked together about the axle 35 in the clockwise direction, as viewed in Fig. 4, to separate the contacts of switch 49 through the previously described action of the plunger 5| and resilient element 52. The separation of the contacts-of switch 49 causes deenergization of the magnetic clutch S and of the solenoid 2|. There-,- fore, longitudinal movement of the carriage and cross-slide I0 is momentarily halted, and the core 23 of the solenoid acts on the finger l6 through the arm 20 to further depress valve member l4 and cause transverse movement of the cross-slide in the direction moving the tool 8 and tracing member 42 away from the work piece and template, respectively. As soon as the cross-slide has been moved transversely in the above indicated manner, the forces acting on the tracing member 42 to cause rocking about the axle 35 are reduced so that the spring 4'! can again return the finger 6 to its position against the stop 48 and the contacts of switch 49 are again closed to energize the solenoid 2| and the magnetic clutch 6, Thus, the longituzdinal feed of the carriage is resumed and the core 23- of the solenoid is raised to permit valve member I4 to return to a position equalizing the forces on both sides of the piston 9. However, the resumed longitudinal movement of the carriage again presses the tracing member 42 against the steep slope of the template to again cause opening of the contacts of switch 49 in the mantudinal movement and producing transversal movement of the cross-slide. Thus, as the trac ing member 42 of the tracing mechanism 1 rides on a relatively steep slope of the template I, as in Fig. 5, the tool 8 will have successive and alternating transversal and longitudinal movements imparted thereto so that the steep slope is reproduced on the work piece I in a step-by-step manner, as illustrated. v

From the foregoing description of an illustrative embodiment of our invention it is apparent that all transverse movements of the cross-slide In result from hydraulic actuation, and that an electrical control for that hydraulic actuation comes into operation in reproducing slopes on a template which exceed a predetermined steep ness. Thus, the simplicity and accurate performance of hydraulic actuation are achieved while producing a copying latheofthe described character capable of reproducing steep slopes, for example, slopes of from 60 to 90.

While an illustrative embodiment of the invention has been described in detail, it is to be understood that the invention is not limited to the precise details thereof and that various changes and modifications may be made therein without departing from the spirit or scope of the invention as defined in the appended claims.

What is claimed is:

l. A tracing mechanism for use in a machine duplicating the contours of a template; said tracing mechanism comprising a tracing head mounted for movement longitudinally along a template and for transverse movement toward and away from the template, a tracer member disposed for contact with the surface of the template, pivotal mounting .means supporting said tracer member on said head for rocking relative to said head about a first axis parallel to the direction of longitudinal movement of said head and about a second axis normal to said first axis, hydraulic means for effecting transverse movement of said head toward and away from the template, valve means operative to control the operation of said hydraulic means and engaged by said tracer member to control said hydraulic means in response to rocking of said tracer memher about said first axis, normally closed switch means, switch actuating means engaged by said tracer member and operative to open said switch means in response to rocking of said tracer member about said second axis, resilient means yieldably resisting rocking of said tracer member about said second axis in the direction causing opening of said switch means so that said tracer member normally rocks only about said first axis and rocks about said second axis only when a slope is encountered on the template having a steepness exceeding a predetermmed value, a solenoid coil on said head, a movable core in said coil, spring means continuously urging said core to project from said coil, said coil being arranged to move said core in the direction opposite to the action of said spring means when said coil is energized, means interposed between said tracer member and said core to be engaged by the latter when said coil is de-energized and to rock said tracer member about said first axis in the direction causing transverse movement of said head away from the template, means for effecting longitudinal movement of said head along the template and including electrically energized transmission means, a source of electric current, and electric circuit means having said switch means interposed therein and connecting said coil and said transmission means to said source so that said transmission means and said coil are de-energized when said tracer member rocks about said second axis to halt the longitudinal movement of said head and to simultaneously cause transverse movement of the head away from the template.

2. A tracing mechanism for use in a machine duplicating the contours of a template; said tracing mechanism comprising a tracing head mounted for movement longitudinally along a template and for transverse movement toward and away from the template, a tracer member disposed for contact with the surface of the template, means supporting said tracer member on said head for movement relative to the latter in the directions of said longitudinal and transverse movements of said head, hydraulic means controlled in response to the movement of said tracer member in said direction of the transverse movement or said head for effecting said transverse movement of the head toward and away from the template, normally closed switch means, switch actuating means operated by said tracer member and effective to open said switch means in response to movement of said tracer member in said longitudinal direction or movement of said head, resilient means yieldably resisting movement of said tracer member in said longitudinal direction of movement of said head in the sense causing opening of said switch means so that said tracer member normally moves relative to said head only in said transverse direction of movement of the latter and moves in the other of said directions only when a slope is encountered on the template having a steepness exceeding a predetermined value, a solenoid coil on said head, a movable core in said coil, spring means yieldably urging said core to move in one direction relative to said coil, said coil being arranged to move said core in the direction opposite to the action of said spring means when said coil is energized, means interposed between said tracer member and said cor to be engaged by the latter when said coil is de-energized and to act against said tracer member in the direction causing transverse movement of said head away from the template, means for effecting longitudinal movement of said head along the template and including electrically energized transmission means, a source of electric current, and electric circuit means having said switch means interposed therein and connecting said coil and said transmission means to said source so that said transmission means and said coil are deenergized when said tracer membermoves in the direction causing opening of the switch means to halt the longitudinal movement of said head and to simultaneously cause transverse movement of the head away from the template.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date ,518,114 Shaw Dec. 21, 1924 1,840,853 Shaw Jan. 12, 1932 1,948,617 Hoagland Feb. 27, 1934 2,007,899 Shaw July 9, 1935 2,025,748 Howe Dec. 31, 1935 2,101,712 Johansen Dec. 7, 937 2,347,367 Rosen Apr. 25, 1944 2,375,831 Turchan May 15, 1945 2,386,825 Turchan Oct, 16, 1945 2,422,682 Johnson June 24, 1947 2,470,244 Fryklund May 17, 1949

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