US1876248A

US1876248A - Metal working machine

Info

Publication number: US1876248A
Application number: US155262A
Authority: US
Inventors: Krebs Henry
Original assignee: Packard Motor Car Co
Current assignee: Packard Motor Car Co
Priority date: 1926-12-16
Filing date: 1926-12-16
Publication date: 1932-09-06
Anticipated expiration: 1949-09-06

Description

Sept. 6, 1932. r .4, KREBS 1,876,248

METAL WORKING MACHINE Filed Dec. 16 1926 5 Sheets-Sheet l Sept. 6, 1932. H. KREBS 1,876,248

METAL WORKING MACHINE Filed Dec. 16, 1926 5 Sheets-Sheet 2 Ila/en oin ATTORN EYS Sept. 6, 1932. KREBS 1,876,248

METAL WORKING MACHINE Filed Dec. 16, 1926 5 Sheets-Sheet 5 Sept. 6, 1932. H. KREBS 1,376,243

METAL WORKING MACHINE I Filed D90- 16, 1926 5 Sheets-Sheet 4 Sept. 6, 1932! KREBs 1,876,248

T ig. 6.

METAL WQRKING MACHINE Filed Dec. 16, 1926 5 Sheets-Sheet 5 Patented Sept. 6, 1932 UNITED STATES PATENT orrice HENRY Keene, OF season, mom-can, Ass caoe T6 PAGKARDMCWOR can CGMPANY, or person, intents-AN, A CORPORATION or MICHIGAN META woexme MACHINE Application flied December 16', 1926. Serial 1%. 155,262.

This invention relates to metal working machines, and while capable of general use, is particularly adapted for machining the walls or surfaces of compression recesses formed in Q cylinder heads for hydrocarbon motors.

It has heretofore been proposed to cast cylinder heads with compression recesses therein of tapered depth, but this method is defective in that irregularities frequently occur in the contours of the compression recesses, with the resulting variation in compression of the several cylinders of the hydrocarbon motor. It has further been proposed to ma chine the walls or surfaces of the tapered F compression recesses so as to avoid the disadvantage above referred to, and it is'the principal object of this invention to provide a 7 novel manner of machining a type .of tapered compression recess that is undercut at its deeper portion around the valves to provide certain recognized advantages over tapered compression recesses heretofore employed.

ther objects of this invention are to provi'de improved mechanism for machining cyl-.

inder head compression recesses of tapered depth, which enables such recesses to be undercut at the deeper portions thereof around the valves; which includes a swinging workholder or cradle that is automatically .oscillated during the operation of the machine and controlled so that the mill or cutter may be entered in and withdrawn from the work at the shallower part of the compression recess which embodies, in addition tothe swinging work-holder, a mill or cutter that is automatically moved in directions angularly related to each other and to the direction of movement of the work-holder, so that the compression recess may be machined and undercut ina closed path beginning and ending at the shallower part of the recess; which produces, in addition to the aforesaid movements of the mill or cutter and the workholder, a movement of one with respect to the other which enables the angle that the mill or cutter makes with the work to be varied whereby a part of said work may be more expeditiously machined, and which is asimply constructed, inexpensive and highly efficient mechanism for ma cl;1ining and undercutting recesses of any desired physical shape. j v

In order to more clearly understand this invention,,reference may he had to the accompanying drawings which illustrate one embodiment of the inventive idea and wherein I Fig. l is a front view of a metal working machine embodying the present invention;

Fig. ,2 is a side, view of the machine illustrated in Fig. 1 looking from the right thereof; 1 3

Fig. 3' is an enlarged perspective view-with parts omitted, showing the driving connections for the various movable parts of the machine;

Fig. 4 is an enlarged perspective view, partly in section, of a yoke and a cradle or work support trunnioned thereon Fig. 5 is a perspective view of the cradle or Work support shown in Fig. 4, looking from the rear thereof; 7

Fig. '6 is a bottom plan view of a cylinder head, showing diagrammatically the machining and undercutting operations;

Fig. 7 is an enlarged view of a rose end mill or cutter; I

Fig. 8 is a sectional view on the line 88 of Fig. 6; c

Fig- 9 is an enlarged view of end mill or cutter, and V Figs. 10, 11 and 12 are sectional views on the lines 10-10, 11-11, and 12 12, respectively, of Fig. 6.

Referring to the drawings, wherein like reference characters designate like parts throughout the several views, 5 indicates the base of the machine" provided at the rear thereof with a vertical column 6 having a forwardly curved head 7 that overhangs a table 8 at the top of the base 5, (F igs. 1 and Q) provided on the front face thereof with m) another rose 39

r ways

14, 14, on which is mounted a horizontally movable slide that carries in su1table bearings thereon, the vertical spindles 16, 16 of a plurality of rose end mills or cutters 17, 17 disposed in spaced relation and arranged in a row at the front of the ma chine.

The table 8 is provided with ways 18, 18 that extend from the front toward the rear of the machine, and mounted on the ways 18, 18 is a horizontally movable slide 19 that carries a yoke 20 which is bolted or otherwise suitably secured to slide 19 at 21, 21. Trunnioned in

suitable bearings

21, 21, on the upper ends of the

yoke arms

22, 22 is a swinging work-holder or cradle 23 that is provided on the bottom 24 thereof with curved

slotted guides

25, 25, which engage

guides

26, 26 of corresponding curvature formed on gu de blocks 27, 27 (Figs. 2 and 4). These guide blocks 27, 27 are provided on the bottoms thereof with

guides

28, 28 slidably mounted in

slots

29, 29 formed in the yoke 20, there being

machine screws

30, 30 threaded through suitable openings in the yoke 20 so as to engage opposed extremities of one of the

guides

26, 26 and thereby serve as means for adj usting the same with respect to one of the

guides

25, 25. The other guide 26 may be adjustably secured to the yoke 20 by

machme screws

30, 30 which extend through suitable openings in the corresponding guide block 27 and are threaded into the yoke 20. The

cradle 23 has bolted or otherwise suitably secured to the top thereof, an open frame 31 through the elongated opening 31 of which the mills or cutters 17, 17 are inserted and withdrawn so as to be engaged with or di engaged from the work. As herein disclosed, the work consists of a cylinder head 32 (Figs. 1, 2 and 6) that is supported in the cradle in an inverted position against the open top frame 31 and provided with

compression recesses

33, 33 of tapered depth which are machined and undercut in accordance with the present invention. The cylinder head 32 is placed within the cradle through the front thereof which is open for this purpose, said head preferably being first engaged with

pins

34 and 35 on the cradle and thereafter clamped against the frame 31 of the cradle by a clamping head 36.

The clamping head 36 is rotatably secured on the upper end of a vertical screw-shaft 37 threaded through a suitable opening in the bottom 24 of the cradle and adapted to be adjusted vertically whereby the work is clamped against the top or frame 31 of the cradle by the clamping head 36. The clamping head 36 is provided at the rear thereof with pins 36,36 (Figs. 2 and 4) that project through slots 36", 36 in the rear wall of the cradle and serve to guide said clamping head as it is raised or lowered with the screw-shaft 37. Vertical adjustments of the screw-shaft 37 and the clamping head 36 are obtained by a hand-wheel 38 threaded on the screw-shaft 37 and rotatably mounted on the bottom of the cradle, the rim of this hand-wheel entering a recess 39 in the back of the cradle whereby said wheel is prevented from mov ng along the screw-shaft as the wheel is rotated. In order to prevent undue strain on the top and bottom walls of the cradle by the clamping of the work therein, said cradle is provided with a strut bar 40 that extends across the open front of the cradle and is pivoted at 41 to the frame 31 so that said strut bar may be swung upwardly out of the way when the work is being placed in the cradle. After the work has been placed in the work-holder or cradle, the bar 40 is swung downwardly and secured to the bottom wall of the cradle by a block 42 adjustably secured on the lower end of said bar which block engages the under side of a lug 43 on the bottom wall of the cradle. This lug 43 is slotted as shown in Fig. 4, to receive the lower end of the bar 40 and the block 42 is removably secured to said lug by a screw 43 or other suitablefastening means. After the lower end of the bar 40 has been secured to the bottom of the cradle, the work is clamped in the cradle as above described.

The cradle is oscillated and stopped automatically by means hereinafter described, and the timing of said means is such that when the cradle is stopped it will assume the full line position shown more clearly in Fig. 2, in

which position the cylinder head 32 may be" readily placed in the cradle so that on lowering the mills or cutters 17, 17 through the opening 31 they may be initially engaged in the

tapered compression recesses

33, 33 at the shallower portions thereof. This initial engagement of the mills or cutters with the work may be obtained by any suitable means, but as here shown this means is preferably comprised by the following devices.

Journalled in a bracket 44 secured on the overhanging head 7 is a screw-shaft 45 (Fig. 2) that is threaded through a lug or fixed nut 46 on the back of the slide 11 and retained against displacement by

collars

47, 47 that are fixed on the shaft 45 at the opposite sides of The slide 13 is provided with open sided lugs 52, 52 adapted to receive bolts 53, 53 that are pivoted at 54, 54 on the slide 11 and provided on their outer ends with wing nuts 55,

55 that may be clamped on the lugs 52, 52 in order to produce raising and lowering move- 33, 33. parts carried thereby is preferably counter-- ments of the

slides

13 and 15 with the slidell when corresponding movements are imparted to the latter by the screw 45 and described are clamped to the slide 11 by the bolts 53, 53 and

wing nuts

55, 55. Thereafter the handwheel 51 is turned to move. the slide 11 so that the mills or cutters 17, 17 are lowered through the cradle opening 31 into the shallower portions of the compression recesses Movement of the slide 11 and the balanced by a weight 56 disposed within a housing portion 57 on the column. 6 and secured to one end of a cable 58 which extends into the housing portion '57 through a suitable opening therein. This cable 58 passes over sheaves or pulleys 59, 59 and 60 mounted on the column 6 and the head 7 thereof respectively, and the opposite end of said cable is secured at 61 to the top of'the slide 11. After the mills or cutters 17, 17 have been engaged in the

compression recesses

33, 33 as above described, the drive for the cutters is then connected therewith to rotate the same and the cradle and the cutters are swung relatively to make an initial cut in the dome of each compression recess, said initial cut being such as to machine the major portion of the recess preparatory to profiling and undercutting operations that are performed by other mills or cutters 17, 17 (Figs. 1, 9, 10 and 11) on further movements of the cradle 23 and reciprocation of the

slides

13 and 15.

The mechanism for driving the cutters and for swinging the cradle may be of any suit able construction, but as here shown, sa d mechanism is preferably comprised by the following devices. Mounted on a bracket 62 bolted or otherwise suitably secured to the column 6, is an electric motor 63 the armature shaft 64 of which. has fixed thereon a pulley 65 over which passes a belt 66 (Figs. 1, 2 and Said belt also passes over a pulley 67 fixed on the main driving shaft 68 of the machine, this shaft 68 being ournalled in suit able hearings on the vertically movable slide 13. A suitable belt-tightener, such as a spring loaded idler pulley of conventional type, may be employed to maintain an even tension on the belt 66 if deemed desirable. Rigidly secured on the main driving shaft68 is a worm 69 which meshes with worm-gears 70, 7O fixed on the cutter spindles, 16, 16 that are carried by the slide 15 as above described. Freely mounted on one end of the main driving shaft 68 is a bracket 71 in which is journalled a short shaft 72 (Fig. 3) having fixed on one end thereof a bevel gear 73 that meshes with a. similar gear 74 rigidly secured on said main driving shaft. The opposite end of the 'shortshaft 72 has a squared telescopic fit in of which is connected by a'universal joint 76 with one end of a second short shaft 77 journalled in suitable bearings in the column .6 of the machine. This short shaft 77 has fixed 0n the opposite end thereof a bevel gear 7 8" which meshes with a similar gear 7 9 rigidly secured on the lower end of a vertical shaft 80 that is journalled in suitable. bearings in the machine column 6. Y

The upper end of the shaft 80 has fixed thereon a worm-wheel 81 that meshes with the column 6. The opposite extremity of the shaft 83 has fixed thereon a worm 84 that meshes with a. worm-wheel 85 fixed on the 1 upper end of a second vertical shaft 86 journalled in suitable bearings in the column 6.

Thisshaft 86 extends downwardly into the base of the column 6 where it is provided with a worm 87 that meshes with and drives a worm wheel 88. The worm-wheel 88 isfixed on a horizontally disposed shaft "89 journalled in suitable bearings in the column 6 and carrying a cam 90. Engaged in the groove 90 of the cam 90 is a roller 91 mounted on a lever 92, the lower end of which is pivoted at 93 in the base of the column '6 (Figs. 1 and Pivotally connected with the upper end of the lever 92 is one end of a rod 94 the opposite end of which is pivotally connected with a lug 95 that is formed on and extends rearwardlyfrom the cradle 23. The rod 94; is preferably made in two parts conneoted for adjustment of the cradle 23 with respect to the cam 90, by a turnbuckle 96, and in order to provide maximum clearance for the rod 9 1 as it is moved by the cam 90 to swing the cradle 23, the slide 19 is. preferably formed at the rear thereof with a slot 97 (Fig. 2) disposed in alinement with said rod.

The mills or cutters 17, 17 having been engaged in the shallower parts of the compression recesses 33, 33 as above described, the drive for said cutters is started as by throwing the switch for the motor 63. With the mills 0r cutters 17, 17 rotating and the parts in the position shown in Figs. 1 and 2, a clutch, to be presently described, is then tripped to connect the cradle operating mechanism with the main drive shaft 68 so that the cradle 23 is swung relatively to the mills or cutters, first rearwardly, and then forwardly, whereupon said clutch is operated automatically to disconnect the drive for the cradle which is stopped in the full line position shown in Figs. 1 and 2. This clutch may be of any suitable construction but as herein shown preferably-includes and is operated by the following instrumentalities,

The worm 82 that is loosely mounted on shaft 83, has secured to or formed integrally therewith a cone clutch element '98 which is also loosely mounted on the .shaft 83. :FiX-Qd on the shaft 83 for sliding movement along the same is a cone clutch element 99 that is urged toward the clutch element 98 for engagement therewith by a compression spring 100 (Figs. 1, 2 and This spring 100 is preferablyhoused in the hub of the clutch element 99 and is held under compression between said clutch element and a fixed abutment (not shown). The spring 100 moves the clutch element 99 into engagement with the clutch element 98 through the controlled action of a clutch operating lever 101 having a yoke 102 embracing the hub of the clutch element 99 and trunnioned thereon at 103, 103. The'lower end of the clutch operating lever 101 is pivotally mounted at 104 on one end of a toggle formed by links 105 and 106 pivotally connected at 107 and mounted on a fixed pivot 108 carried by the overhanging head 7 of the column 6. A. toggle operating rod 109 that is also pivotally connected at 107 to the toggle links depends therefrom and is pivotally connected at 110 to one end of a treadle 111 provided with a foot plate 111. This treadle is pivoted at 112 on the base 5 of the machine and connected at 113 with one end of a spring 114, the opposite end of which is connected with a pin 115 located above the pivotal point 112 and secured to the base 5. The spring 114 normally tends to lift the treadle and pull the rod 109 downwardly so that the links 105 and 106 ar held substantially in alinement and hold the

clutch parts

98 and 99 disengaged. A pin 116 secured to the overhanging head 7 serves to prevent movement of the links 105, 106 downwardly beyond their substantially alined position, and adjustment of the length of the rod 109 is provided for by making the same in two parts connected with a turnbuckle 117.

The shaft 89 has secured. to one end there of a bevel gear 118 that meshes with a bevel gear 119 fixed on the lower end of a vertical shaft 120 journalled in suitable bearings on the base 5 and overhanging head 7. The upper end of said shaft 120 has fixed thereon a bevel gear 121 that meshes with a similar gear 122 secured on a horizontal shaft 123 that is journalled in suitable bearings on the overhanging head 7. The gearing 118, 119 and 121, 122 is such that the shafts 120 and 123 are driven at the same speed the shaft 89 and the shaft 123 has adjustably secured thereon a disk 124 provided at diametrically opposite points

wi h rollers

125 and 126, each adapted on a half revolution of the shaft 89 and the cam 90, to engage a cam 127 projecting from one side of clutch operating lever 128.. This lever 128 has a forked end 129 that engages over the shaft 123 and a yoke end 130 that is pivotally connected at 131, 131 with the upper end of the yoke 102.

In the position of the parts shown more clearly in Figs. 1 and 3, and with the mills svaars cradle 23. The cradle is thus swung by the rod 94 and cam as described, the shape of the portion of the cam groove 90 then engaged with the roller 91 preferably being such that on a half revolution of the shaft 89 the cradle will be swung once toward the 80 rear and then once toward the front of the machine through a distance somewhat less than the distance between the shallower and deeper ends of the compression recesses 33,

33. After the drive for the cradle operat-Sa ing mechanism has been established, the disk 124 is rotated a half revolution, during which time the roller 125 rides onto the cam 127, whereupon the latter with the lever 128 is moved to the left against the' so action of spring 100 on lever 101. In this movement of the lever 101 to the left, the latter swings about the pivot 104 by reason of the fact that the operator has released the treadle 111 and the toggle levers 105, 106 are returned to their substantially alined position by the spring 114. l Vhen the roller 125 engages the cam 127, the lever 101 will therefore disengage the clutch 98, 99- and discona nect the drive for the cradle operating mechanism, the cradle stopping at approximatelv its full line position shown in Fig. 2 of the drawings.

During the first half revolution of the cam 90 and the resulting movement of the cradle 23, the mills or cutters 17, 17 make initial cuts in the compression recesses 33, 33 and machine the major portion of the dome of each recess. These are straight cuts obtained without lateral movement of the work or cut-"11 ters and are identical in configuration. The margins of one of these initial cuts is indicated diagrammatically at A in Fig. 6, and one of the mills 17 17 and a cross-section of the initial cut produced thereby are illustrated in Figs. 7 and 8. The distance above referred to, through which the cradle 23 swings while the initial cuts are being made in the compression recesses 33, 33 is pointed out as being less than the distance between 'tzo the shallower and deeper ends or the recesses, and the reason for this is that the cylinder head 32 herein illustrated has

reentrant portions

32, 32 at the deeper ends of the compression recesses which portions preferably are not machined by the mills or cutters 17, 17. It will of course be understood, however, that the cradle 23 may be swung through any distance desired to meet various operating conditions, and that this initial or any other 33 Immediately upon breaking the 70 completion of the half revolution of the cam 90 and dish 124, the drive for the cutter spindles 16, 16-is stopped as by again throwing the switch for the motor 63. The slides,

11, 13 and 15 are then elevated by turning the handwheel 51, so that the mills or cutters 17, 17 are withdrawn from the work 32 and the cradle 23.

or cutters 17, 17 (Figs. 1, 9, 10 and'll) are substituted therefor and the several slides are lowered together by the handwheel 51 until said mills or cutters 17, 17 pass through the frame 31of the cradle and engage the walls of the compression recesses 33, 33 at the shallower portions thereof, The bolts 53, 53 are then unclamped from the lugs 52,52 and swung clear ofQt-he latter so that the

slides

13 and 15 are free to move independently of the slide 11 which remains stationary atany desired position through its engagement with the screw 45. lVith the mills or cutters 17 17 engaged in the work, it is ready for pro-f :wi filing and undercutting which preferably, is a combined operation obtained by simultaneously rotating the mills or cutters 17 17, swinging the cradle 23, andv reciprocating the slides 13'and 15. The slide 19 may also be,

: andpreferably is, reciprocated during this, operation by means, and for apurpose, to be,

The drive for the zontally will now be described and the same f preferably consist of the following instrumentalities.

Fixed on the shaft 89.is a spur gear 132 that meshes with a similar gear 133 fixed on a horizontal shaft 134 ournalled in suitable hearings in the column 6. The gears 132 and 133 preferably have equaldiameters so that the shaft 134 will be driven at the same speed as the shaft 89. Fixed on the shaft 134 is a cam 135, the groove 136 of which is shaped 5 so that during the first half revolution of the shafts 89'and 134 a. portion of said groove is concentric with the axis of the shaft 134 and no motion is imparted to a rod 137, the lower endof which is provided with a roller enin the cam groove 136. During the second half revolution of the shafts '89 and 134, however, said rod is moved by a portion of-the cam groove 136. to reciprocate'the slides 13 and 15 vertically-so thatlike mo tion is imparted to the rose endmills or cutters 17 17'; To this end, the rod 137 is pivotally connected at 138 with one extremity of a lever or walking beam 139 pivotally mounted at 140 on the overhanging head 7 of the machine. The opposite extremity of this walking beam is pivotally connected at 141 with one end of a two part rod 142 that is pivotally connected at 143 with the slide 13 and provided with a turnbuckle 144 whereby the length of the rod 142 may be adjusted I as desired (Figs. 2 and 3). The rod 137 may also, if desired, be made a two part rod detachably connected together to provide for After the mills or cutters 17, 17 have been raised clear of the cradle, the rose end mills relativemovement of its parts during raising and lowering of the slide 11 by means of the hand wheel 51, relative motion between the parts of the rod during the -auto-' matic operation of the device being prevented provided in order to prevent lateral motion thereof, the same not being illustrated in the drawings for the sake of simplicity and clarity.

Referringnow to the slide 15 on which the spindles 16, 16 for the mills or cutters are journalled, this slide is reciprocated laterally or horizontally as it is being reciprocatedvertically with the slide 13,-and for this purpose the shaft 86 has fixed thereon a worm 145 that meshes with a wormvwheel 146 secured on a horizontal shaft 147 journalled in suitable bearings in a housing portion 148 extending from one side of the column 6 .(Figs, 1, 2 and The shaft 147v extendsthrough the housing portion 148, at

thefront of the machine and has fixed. on

the projecting end a cam 149, the groove 150 ofwhich is so shaped that during the first half revolution of the shaft 89 and cam a portion of the cam groove 150 is concentric with the axis of the shaft 147 and no motion is imparted to a rod 151, one end of which is provided with a roller 152 engaging in the groove 150. During the second half revolution ofthe shaft 89 and cam 90, however, the groove of the cam 149 acts to move the rod 151 and reciprocate the slide 15 horizontally. For this purpose the rod 151 is pivotally connected to said slide at 153, and has a toggle connection with shaft 147 through a'link 151 suitably pivoted at its ends to said rod and shaft as clearly shown in Figs. 1 and 3 of'the drawings.

Assumingnow, that the machine has been set up for the profiling and undercutting of the work and that the mills or cutters 17 17 are'engaged with the work 32 in the shallower parts of the compression recesses 33, 33, the drive for the cutters is started to rotate the same, as by again throwing the switch for the motor 63, and the operator depresses through engagement of the

clutch elements

98, 99. After the drive for these various instrumentalities has been established, the shaft 89 and cam 90 make a second half revolu- ;tion in the course of which the roller 126 rides onto the cam 127 which thereupon moves to the left (Fig. 3) as before and engagement of the roller 126 with the cam 127 disconnects the

clutch parts

98, 99 and therefore stops the movement of the slide and cradle operating mechanisms at the end of the second half revolution of the shaft 89 and the cam 90. The positions of the relatively movable parts when the operation is stopped at the end of the second half revolution of the cam 90, is substantially thesame as shown in full lines in Figs. 1 and 2 of the drawings.

During the second half revolution of the cam 90, however, the mills or cutters 17, 17, and the cradle and

work

23, 32, are swung relatively and have relative rectilinear movementssimultaneously imparted thereto in a plurality of directions that are angularly related to each other and to the direction of swinging movement. These relative movements result in a machining of the walls of the compression recesses 33, 33 in closed paths.

beginning and ending at the shallower parts of said recesses, and undercutting of said walls at the deeper portions of the recesses. These closed paths are identical in configuration and one of them is indicated diagrammatically in Fig. 6 where B represents the path of the aXis of the cutter and C, D, E, F,

' G, H and I represent, in the order named,

positions successively occupied by the cutter as the later and the work are moved relatively in the manner stated. The undercutting 4 preferably begins at the position D, ends at the position H, and is greatest at the positions E and G where are located the deeper portions of the recess that lie over the valves when the head 32 is secured on the internal V combustion engine.

In performing the machining and undercutting operation with the mills or cutters 17, 17, the latter and the work, as herein shown, are moved relatively in three planes each at right angles to the other two. The motion in a horizontal plane and in a direction toward and away from the deeper or valve pocket ends of the compression recesses, is obtained by swinging movement of the cradle 23 during the second half revoluters 17, 17 to machine and undercut at the extreme, deeper ends of the compression recesses.

The depth of the cut, during the machining and undercutting operation, is obtained by the vertical component of the motion of the swinging cradle and by the vertical motion of the slide 15 and cutters 17', 17, which during swinging movement of the cradle 23, are reciprocated vertically with the slide 13 by the cam 135, rod 137, walking beam 139 and rod 142. The width of the machining and undercutting is obtained by the horizontal motion of the slide 15 and cutters 17, 17 which, during swinging movement of the cradle 23 and vertical reciprocation of slide 13, are reciprocated horizontally or lengthwise of the cylinder head 32, by the cam 149 and rod 151.

In addition to the described simultaneous motions of the parts occurring in the course of the machining and undercutting operation, an additional motion is preferably introduced at this time lasting only for a'predetermined interval of time in order to enable the mills or cutters 17, 17 to more readily machine and undercut adjacent the

reentrant portions

32, 32 of the cylinder head. This additional motion is preferably imparted to the slide 19 near the end of the rearward traverse of the cradle 23 and varies the angular relation between the mills or cutters 17 17 and the work during the time that the mills or cut ters 17 17 are adjacent the

reentrant portions

32, 32 of the cylinder head in a manner clearly illustrated in Figs. 10 and 11 of the drawings. For the purpose of changing the angular relation of the mills or cutters 17', 17 with the work when said cutters reach the

reentrant portions

32, 32 of the cylinder head, the shaft 134 has fiXed thereon a pair of cams 153, 153', the grooves 154, 154 of which rotate concentrically with the shaft 134 during the major portion of acomplete revolution thereof, so that no motion is imparted to a pair of

rods

155, 155 provided with rollers 156, 156 engaged in the cam grooves 154, 154. These

rods

155, 155 extend from the cams 153, 153' to opposite sides of the slide 19 and are pivotally connected therewith at 157, 157. It will be understood that suitable guide bearings, not shown, are provided for the ends of rods 155 adjacent the cam mem- 19 and this slight reciprocation of said slideis converted into a slight forward and rear tilt of the cradle 23 that Varies the angular relation between the work and the cutters 17, 17, enables the latter to more accurately follow the margins of the

reentrant portions

32, 32, and undercut the walls of each

reentrant portion

32, 32 to a depth that is somewhat less than the depth of the undercutting at the cutter positions E and Gr, shown in Fig. 6. The depth of the undercut at the position G is clearly shown in Fig. 10 and the depth of the undercut at one of the

reentrant portions

32, 32 is clearly shown in Fig. 11.

In the machine herein illustrated, it is preferable to brace the yoke 20 by connecting one ofits

arms

22, 22 to the column 6, and as clearly shown in Fig. 2, this is accomplished by means that provide for reciprocation of the slide 19. Said means consists of a plunger 158 that is bolted at 159, 159 to a projecting part 160 of the yoke arm, and a bracket 161 bolted at 162, 162 to the column 6 and having a cylinder 163 in which the plunger 158 is slidably fitted.

.As above pointed out, the roller 126 and cam 127 stop the operation of the machine at the end of the second half revolution of the cam 90, at which time the machining and un dercutting has been completed so that'the walls of the compression recesses 33, 33 are undercut substantially as indicated diagrammatically at K, K in Fig. 6 ofthe drawings. As herein disclosed, the cradle 23, during the initial cutting or machining operation, is swung once toward the rear and then once toward the front of the machine, and said cradle, during the machining and undercuttingoperation receives a similar movement 40 accompanied. by reciprocation of the

slides

13 and 15. It is to be expressly'understood, however, that in either or both of these operations the cradle may be swung repeatedly and that during the machining and 4 undercutting the

slides

13 and 15 may be repeatedly reciprocated through the employment of devices suitable for these purposes and embodying the principles of the above described cradle, clutch, and slide'opcrating devices.

it is to be further understood, that while one embodiment of this invention is herein illustrated and described in detail, the invention is not limited thereto but may be embodied in a variety of mechanical expressions within the scope of the appended claims.

cutter'and arranged to swing on an axisex' tending transversely of the axis of rotation of the mill orcutter, said cradle being adapted to support a cyhnder head thereon with the compression recess faced toward, and its wall engaged with, the mill or cutter, means for rotating the mill or cutter, and means causing said mill or cutter to machine the entire wall of the compression recess and comprising mechanism for automatically swinging said cradle in opposite directions,

and mechanism for automatically reciprocating the rotating mill or cutter along a 11116 substantially parallel with the axis of swing of the cradle and said cylinder head.

2. In a machine of the character described,-

a rotatable mill or cutter adapted to machine the wall of a cylinder head compression recess, a swinging-cradle adapted to support the cylinder head with the compression recess faced toward, and its wall engaged with, the mill or cutter, a support on which the cradle is arranged to swing about an axis extending transversely of the axis of rotation of the mill or cutter, and means causing said mill or cutter to machine the entire wall of the compression recess mechanism for automatically swinging the cradle and cylinder head in opposite directions and mechanism for automatically re-.

and comprising.

ciprocating the rotating millor cutter in the direction of depth of said recess and along a line substantially parallel with the axis of swing of the cradle and said cylinder head.

3. In a machine of the character described, a rotating mill or cutter adapted to machine 7 the wall of a cylinder head compression remechanism for automatically reciprocating the rotating mill or cutter rectilinearlyin angularly related dlrections, and guide meansfor the oscillating cradle comprising a slotted rib or extension formed on theun der side thereof and a guide block en agedin the slot of said rib and adjustably mounted in the slot of saidsupport.

described,

a. In a machine of the character a rotating mill or cutter adapted to machine the wall of a cylinderhead compression recess, a swinging cradle adapted to support the cylinder head with the compression recess faced toward, and its surface engaged with, the rotatmg mill or cutter, a support on which the cradle is arranged to swing about an axis extending transversely of the axis of rotation of the mill or cutter, said support having spaced parallel slots formed therein below the cradle, means causing said mill or cutter to machine the entire surface of the compression recess and comprising .angularly related directions, and means for guldlng the swinglng cradle comprising spaced parallel ribs or extensions formed on the under side thereof and having curved slots therein, and guide blocks adjustably mounted in the slots of said support and having curved upper extremities engaged in the curved slots of said ribs or extensions.

5. In a machine of the character described, a pivotally mounted work support, a plurality of mills or cutters arranged to simultaneously engage work carried by the work support, means for rotating the mills or cutters, means for automatically shifting the axis of the pivoted work support toward and away from the mills or cutters during a portion of their cutting operation, and means automatically oscillating said work support while the tools are rotating and engaged with the work.

.6. The combination with a machine tool, of a pivotally mounted cradle having an opening in one side thereof, a device on an adjacent side of the cradle for clamping work to the opposite side thereof, an element pivoted on the cradle to swing across said opening, and means for securing said element to the cradle before the work is clamped thereto, whereby the cradle is strengthened to withstand the force exerted by said clamping de vice.

7. The combination with a machine tool, of means for supporting work to be machined by said tool, said means comprising a hollow swinging cradle open at its top and front sides and closed at the remaining sides, a de vice for clamping the work in the cradle under the open top side thereof, and a member adapted to be secured to the cradle across the open front side thereof after the work has been placed in said cradle and the before said work is clamped therein by said device.

8. The combination with a mill or cutter, of means for supporting work to be machined by said mill or cutter, said means comprising a hollow pivoted cradle having an opening in one side through which the mill or cutter is passed into and withdrawn from the cradle and an opening in another side through which the work is passed into and withdrawn from said cradle, means for clamping the work in the cradle adjacent the opening therein for the mill or cutter, an element pivoted on the cradle to swing across the open ing therein through which the work is passed, and means for detachably securing said element in position across said last-named opening to strengthen the cradle against the force exerted by the clamping means.

9. The combination with a machine tool, of means for supporting work to be machined by said tool, said means comprising a yoke 01' the like, a cradle trunnioned on said yoke to swing the work during the machining operation, a rectilinearly movable screw shaft extending in said cradle, a hand-wheel for turning Said Screw shaft and retained in the cradle against displacement with the screw shaft, and a device mounted on said screw shaft within the cradle and adapted to clamp the work against a part of the cradle opposite said device.

10. The combination with a machine tool, of means for supporting work to be machined by said tool, said means comprising a yoke, a cradle pivoted on said yoke and provided in one side thereof with a slot, a rectilinearly movable clamp operating device extending in the cradle, a clamp rotatably mounted on said device, and a guide pin on said clamp engaging in said slot to prevent rotation of the clamp as the latter is moved by said operating device.

11. In an apparatus for machining recesses in cylinder heads for engines, a rotating tool, a work holder adapted to swing on an axis substantially perpendicular to the axis of the tool, and means for oscillating the work holder and traversing the tool substantially parallel to the axis of swing whereby the tool is caused to machine out a recess of varying width in the cylinder head.

12. In an apparatus for machining recesses in cylinder heads for engines, a rotating tool, a work holder, means for clamping a cylinder head in the work holder with the face to be machined adjacent the tool, and means for rocking the work holder and the cylinder head in opposite directions along a curvilinear path while the tool is in contact with said face, the axis about which said curvilinear movement takes place lying parallel to said face.

13. In an apparatus for machining recesses in cylinder heads for engines, a rotating tool, a Work holder, means for clamping a cylinder head in the work holder with the face to der heads for multi-cylinder engines, a plurality of rotating tools, a work holder, means for clamping a cylinder head in the work holder in position for the tools to machine out a row of recesses in said cylinder head, and means for swinging the work holder in opposite directions along a curvilinear path during the machining operation, the axis about which said curvilinear movement takes place being parallel to said row of re- CGSSBS. V

15.. In; an apparatussioremaehiningrcylins der. heads for. multi-cylinder: engines, a: p11 rality of rotating-tools,,ai ork-hOIdBIamGanS for clamping a: cylindersheadsinzthe Work holden inipositionfor '611'621-t001S-7t0; machine out a row of; recesses therein; meansefor Swinging;the WOrk2hOld0D in ;op.posite dime. tions along a. curvilinear path,- the:axis;&bbut: which; said curvilinear movementitakes-place: being parallel; to. said rem ofrrecesses-,pand means-- for simultaneously; traversing the. tools to I and froinlardirmtion,parallelato said axis during; the-machining;operations,

16. In an apparatns==fon= machining cylin: der heads .for 'multi cylinder engines-angina rality of rotating tools,galwnrk holder; means for clamping a, cylindenheadrim: the-ework holder-win. positionsfor; thQ?ftQQ1S.-ftOi machine out. a row of recesses thereinmeans; for. swinging the; work holderdnzoppositedirece tions along atcurvilineargpath the-axisnbout which.saidicurvilineamm-ovementztakes.iplace being, parallel tosaid. rowaof rece'ssesameans for simultaneously traversing;thentools'a to and fro in. a (liI'GGtiOIl'z parallelrto .said.:..axis, andi'means-for advancing -and;.retnacting:the tools; with IBSPGGlZZitD: the 1 worksto varya-r'the depth-.ofthe: recesses.

17. In;v an. apparatus 2- for: machining: coma-1 pression; recesses-a in cylinder heads fonrem gines, the combination ofs'adrivenurose end mill, a pivoted work;holdenradaptedxto.support alcylinder: head).with;atcompressioniInes cess thereof; facing; toward the millggand. means for. autoinatioally.:oscillatingesaidielea m-ents ,relatively and; simultaneously;imparts; in g relative rectilinear movcments i thereto @in" a plurality of directions. that/.1. arezangulanly; related: to each othenr andxto the directionroft; oscillating: movement,-',Wher.ehy::said: mill is caused to .machinethe Walllfofltheerecess and: undercuti said. "walliao the deeperepart of said: recess; I

18'. .Inw an apparatus a for; machining re.

- cesses in cylinder :heads :for engines, ;.the;com'-..

bination of a rotary rose end milling-tool; a. pivoted Work holder adaptedatorsupport a cylinderhead with 8.3 compression, recess: thereof facingtoward, the) mill-' means afon driving the tool,'means simultaneou lyioscile lating the Work holder and: reciprocating: the tool rectil-inearly-across theypatlr-ofitraveb of the Work holder; andzmeans:fonreciprocane ing the tool in thedirectiom of-ktherdepthrofr the work, whereby :s-aidfmillris'zcausedstoamae chine the Wallof the recess anderundercut said Wall: at the deeper'partioh'saidireeessaz.

19; Inn-machine ofqthe .Cha1'fiGteI dSClihi 5 the combination of a pivotally mountedi cradle adapted totsuppontiaacylindel. head having. a compressionrecess,thereinyadrivena movably: mounted rose; end; millv adapt d: engage the .walL of; said recess. andmotat'abl about: anoxis; extending at. right.: angles to, thepivotal axis .of the. cradle, and-.means-fon,

antomaticall-y v moving; the cradle: and; the mill-relativelyindifirentdirections-where: by; the;-latten machines the: recesswall ,1 and undercutseit-at; thel deeper;partcofethezrecess, 2,0..11-1; 3.1 machine oi; the character -de= scribed-,.. the. combination Of'i as. pivotally mounted cradle adapted-:to;supportsaqcylin der head al driven bodily-movable r0se-.; n milLada-ptedto.machine ':&..('3OII pI'@S l0I1: fi eSS intend; cylinder. :head? and -.I0t&l3tble:;fib ()l1l35fi.-H axis extending; atzrightz nglesi o :the piv tal axis :Q thecradle andlmeans ton oscillating and: bodil moving t-l1e.:.cradle and, the 5 mill relatively; wherebysthe millizmachineseas e: (1QS,S,- th3Wall;-Of; Whichi is -undercut an, the deeper partoflsaidsrccess. i

211;:- 3 In; a machine; of. the, 1' oharactec 1e: seribi'ed the; combination: of; a piv tally mounted cr.-adlezad aptedtosnppmt; a;-;cylin= der head, a driven bodily movablegrose end mill adaptedito machinea;compression reoess' in saidscylinder :head' ,androtatablm ahtmtr n axis {extending at; right; angle to thegypiiviotal aX-is'oftthe cradle, and means. foremovingz he cradleand. the mill relativelyxwherebyr the lattes machines a a recess the; Wall"; of'jwhichzis undercut; at: one; part: thereon; said: means comprisingzdevices eforyoscillatinggthe cradle and; devices. for reciprocating; the ;-to0l-:acr.0s& the: path of; travel 0f.:the cradle-1 and; toward and awayfromtheasame. I

22.; machine of; the?v character; described, the .com-binationof alcradle arrangedto swing :on a-h-orizontal; axis and adapted to. support; a). cylinder head; with; the-:com: pression recesses thereof facedyupwardlyg; a plurality r of drivem ,roseendigmi'lls z'arrangfid. above the. cradle to. rotate aon-sventical: axes and eachaadaptedsto engage; the. Wall; of; one. of 1 the compression recesses, and means for. automatically oscillatingthevcnadle v and? the; mills relatively. and... for: imparting: relative rectilinear movements thereto in a plurality offzdirecti'onsangularly related. o .eacli. oth

and-i-to-the direetiomof;oscillatingvmovemelltg.

Wh'ereby the: mills: machinetherwalls of? the. compression recesses and undercutwsaidnwalls atatliedeeper;'parts:ofasaidrrecessesz;

23;..In': a1 machine of; the:.- character? dee scribedgt. a; .pinotally mounted: cradle, .araverti'l. I

callyrmovab-le slide, as honizontally.v movable slide: carried bynthe' vertically-movable:slide; a rose-endzmill; or ncutten mounted;.onthe -1ast-.

named. slide and adaptedgtn; engageworlo supportedfon. the. cradlenand:automatically operatedv means; rotating :theamillg or cutter,

reciprocating ;-theslides; and swinging; said;

crad1e,--..Wl1ereby; saidi millwisvcansedtte IIljflrchineandi-lmdercut saidlwrorkl 242.111,; a machine of; the. character; described,; asvertically movable slide, ,a; driven shaft journalledithereon, a horizontallymovs able: slide carried :by, the: vertically movable slide, .auroseeend milLor cutterzj ournalled on. thezhorizontally movable. slide and adapted.

to be rotated by said driven shaft, a pivotally mounted cradle adapted to support work that is engaged by the rotating mill or cutter, and automatically operated means reciprocating said slides and oscillating said cradle so that the work thereon is machined and undercut by said mill or cutter.

25. Ina machine of the character described, a pair of slides arranged to be reciprocated substantially at right angles to each other, a plurality of rose-end mills or cutters carried on one of said slides, means rotating the mills or cutters, a pivotally mounted cradle arranged to support work engaged by the rotating mills or'cutters, and means for automatically reciprocating the slides and swinging sait cradle during rotation of the mills or cutters whereby said mills or cutters are caused to machine and undercut said work.

26. In a machine of the character described, a mill or cutter, movable means on which the mill or cutter is mounted, a pivot ally mounted cradle arranged to support work adjacent the mill or cutter, means for manually adjusting the movable supporting means to engage the mill or cutter with said. work, and means for thereafter automatically'rotating the mill or cutter, oscillating the cradle, and reciprocating said movable means in angularly related directions. 27. In a machine of the character described, a plurality of vrose-end mills or cutters, movable 11 cans on which the mills or cutters are carried, a pivotally mounted cradle arranged to support work in engagement with the mills or cutters, and automatic mechanism for simultaneously rotating the mills or cutters, swinging the cradle, and reciprocating said movable means in angularly related directions whereby the mills or cutters are caused to machine and undercut said work, a 28. In a machine of the character described, a pair of slides movable in angularly related directions, a rose-end mill or cutter carried 7 by one of the slides, a pivotally mounted cradle arranged to support work in engagement with the mill or cutter, means for rotating the mill or cutter, mechanism for moving the slides in said directions, and devices for swinging the cradle during rotation of the miller cutter andsaid movement of the slides whereby the mill or cutteris caused to machine andundercut said work.

29. In a machine of the character described, a slide, a second slide carried by the first slide and movablesubstantially at right angles thereto, a rose-end millor cutter carried by one of the slides, a pivotally mounted cradle adapted to support work in engagement with the mill or cutter, means for rotating the mill or cutter, cam operated means for reciprocating the slides, and means for swinging the cradle during rotation of the millor cutter and reciprocation ofthe slides whereby the mill or cutter is caused to machine and undercut said work.

80. In a machine of the character described, a vertically movable slide, a shaft journalled thereon, means for driving the shaft providing for, reciprocation of the slide, a horizontally movable slide carried by the vertically movable slide, a series of mills r cutters carried by the horizontally movable slide and adapted to be rotated by said shaft, a pivotally mounted cradle for supporting work that is machined and undercut by the mills or cutters, means for reciprocatingsaid slides, and means for swinging the cradle during rotation of the mills or cutters and reciprocation of the slides.

31. In a machine of the character described, a vertically movable slide, means for reciprocating saidslide including a cam operated lever orwalking beam, a horizontally movable slide carried by the vertically movable slide, means for reciprocating the horizontally movable slide, a mill or cutter journalled on the horizontally movable slide, means for rotating the mill or cutter, apivotally mount ed cradle arranged to support work that is machined and undercut by the mill or cutter, and means for swinging said cradle during rotation of the mill or cutter and reciprocation of said slides.

32. In a machine of the character described, a rose-end mill or cutter, movable means on which said mill or cutter is carried, means for rotating the mill or cutter, a pivotally mounted cradle arranged to support work in engagementavith the mill or cutter, a pair ofcam shafts, means operated by the cam of one shaft for reciprocating said movable'means rcctilineally in a plurality of angularly related directions, and means operated by the cam of the other shaft for oscillating said cradle during the reciprocation of the movable means, whereby the mill or cutter is caused to machine and undercut said work. V

, 33. Ina machine of the character described, a slide, a second'slide carried by the first slide, amill or cutter journalled on one of said slides, means for driving the mill or cutter, a pivotally mounted cradle arranged to support work that is machined and undercut by the mill orcutter, a pair of cam shafts, means operated by the cam of one shaft for reciprocating thefirst slide, means operated by the cam of the other shaft for swinging said cradle, andmeans for reciprocating the second slide across the path of travel of the first slide.

34. In a machine of the character described, a pair of slides, a rose-end mill or cutter carried-by one of said slides, means for driving the mill or'cutter, a pivotally mounted cradle arranged to support work in engagement with the mill or cutter, and mechanism causing'the mill or cutter to machine andundercut the-work and comprisingcam operated means for-swinging the cradleand reciprocating one of theslides and cam operated means for reciprocating the other slide;

35. In amachine of the character. described, a pair of slides, a:driving shaft journalled. on:one of said slides, a mill orhcutter carried by the otherslide and adapted to be rotated by the driving shaft, a pivotally mounted cradle arranged to support. work that. is machined and undercut by the mill or cutter, a pairof cam shafts gearedxtogether anda-dapted tobe driven by saiddriving shaft,.means operated by one cam shaft for swinging the cradle, means opcratedby the othervcam. shaft for reciprocating one of illGSlldGS, and means operatively connected with the driving shaft: for reciprocating the other slide.

36. In amachine of the character described, aipivoted work support or holder,'a slide mounted. adjacent thereto, a second slide movable across the path of travel of the first slide, aplurality of rose-end mills or cutters carried by one of the slides and adapted to engage workon said work support or holder, means for driving the mills or cutters, and means automatically reciprocating the slides andoscillati'ng the work holder whereby the driven mills or cutters are caused to machine and undercut the work;

87; Ina machine of the character de-- scribed, a slide, a main driving shaft journalled thereon, a second slide carriedby the first-named slide and movable substantially at right angles to its-path of travel, a mill orcutter-carried by the second slide, worm gearing connecting the main driving shaft with said mill or cutter for driving-tl'ie latter, meansfor "reciprocating the iirstshde, and means forrec1procat1ng the second sl1de.

38; In a machine of the character de-- ver or-walking beam operatively connected with the last-named slide, and alink connected at one end with the lever or walking beam and provided at its opposite end with'a roller engaging saidcam.

89; In a machine of the character described, a: rose-end mill. or cutter, means rotatably supporting said mill or cutter, means for driving the mill or cutter,'devices reciprocating said supporting means in one direction and com prising aipivotally mounted lever orwalking beam and a cam operated: member for oscillating said lever or walking beam, means automatically reciprocating the mill or cutter transversely of the path of travel of its supporting means, apivoted work supporting cradle-{and means oscillating, the cradle dur* latter is caused to machine and undercut the work, on' said ,;cradle..

40, In a;machineof the character described, a;pair; ofslides,,one carried by the other and movable across its path of travel,.a plurality of rose endanills-or cutter-s mounted on one of" theslides and adapted to, engage. work supported adjacent thereto,,a drivenashaft, and means automatically operated thereby while'the mills or "cutter-s are engaged with the'work, for. simultaneously rotating; said millsor cutters and reciprocating-said slides whereby the mills or cutters machine and undercut; said worln 41. In a machine of the character described, a slide, a driven shaft carried there-. by, a secondslide mounted on the first slide for'movement across its path of travel, a series of rose end mills or cutters mounted on the second slide, worm gearing connecting said drivenshaft with said mills or cutters so as to rotate the latter during reciprocation of the slides, and means operated by said shaft forv automatically reciprocating bothof said, slides during rotation of said mills or cutters whereby theilatter'machine and undercut. work supported adjacent thereto.

42;. Incombination, a Work holder, a tool, meansautomatically swinging said elements relatively in opposite directions and imparting relative rectilinear movements thereto in a plurality of angularly related directions, whereby the tool machines the work on said holder, and additional means adapted during the machining operation to automatically change the angular relation between the surface of the work and the tool for a predetermined time.

43. In combination, a work holder, a tool" for machining work on said holder, means automatically swinging said elements relaswinging the work holder and the mill or cutter relatively in opposite directions, to machine certaln parts of'the work, means automatically imparting relative rectilinear movements to the workholder. and the mill or cutter during their relative swinging movement, to thereby machine'otherparts'of the v Work, andadditional means operatingiautm f lit matically during one cycle of the machine to change the angular relation between the work and the mill or cutter for a predetermined time.

a5. In combination, a movable support, a work holder pivotally mounted thereon, a tool adapted to machine work carried by the work holder, means for driving said tool, means oscillating the work holder, and means adapted to r ciprocate said support for a predetermined period during the oscillation of said work holder.

46. In combination, a movable support, a work holder pivotally mounted thereon, a tool arranged to machine work carried by the work holder, means for driving the tool, means oscillating the work holder and the tool relatively and imparting relative rectilinear movements thereto in angularly related direc tions, and means adapted to move said support for a predetermined period during said relative movements of the work holder and the tool.

4-7. In combination, a movable support, a work holder pivoted thereon, a plurality of tools arranged to simultaneously machine work carried by the work holder, means for driving the tools, means independent of said support for swinging the work holder and the tools relatively in opposite directions and for imparting relative rectilinear movements thereto in a plurality of directions angularly related to each other and to the direction of swinging movement, whereby said tools machine certain portions of the work, and means for moving said work holder support for a predetermined. period of time during said relative movements to facilitate the machining of other portions of the work.

48. In COllllDlHfltlOIl, a slide or the like, a work holder pivoted thereon, a tool arranged to machine work carried by the work holder, means for driving the tool, means for swinging the work holder and the tool relatively in opposite direct-ion and for imparting relative rectilinear movements thereto in a plurality of angularly related directions, whereby the tool machines certain parts of the work, and mechanism independent of said last named means for reciprocating the tool and said slide relatively at a predetermined time during the operation of the machine, whereby the tool machines another part of the work.

49. In combination, a slide or the lik work holding cradle pivoted thereon, a mill or cutter arranged to machine and undercut Work carried by said cradle, means for rotating the mill or cutter, means for reciprocating the mill or cutter in angularly related directions, means for swinging the cradle, and means independent the cutter and the cradle operating means and adapted to re ciprocate said slide a predetermined time during the operation of the machine.

50. In combination, a support, a work holder pivoted thereon, a tool for machining work carried by said work holder, means for driving the tool, a driven shaft, connections between said shaft and the work holder adapted to oscillate the latter with respect to the tool, a second driven shaft, and con nections between said last-named shaft and said support adapted while the work holder is oscillating to reciprocate the support for a predetermined period of time.

51. In combination, a slidable support, a work holder pivoted thereon, a pair of slides connected together and each movable trans versely of the other, a tool on one slide for machining work carried by said work holder, means for driving the tool including a driven shaft, a plurality of cam shafts, connections between said driven shaft and the cam shafts for driving the latter, means operated by certain of the cam shafts and reciprocating said slides to move the tool in angularly related directions, means operated by one of the cam shafts for swinging the work holder, and means operated by another of the cam shafts for reciprocating said supportfor a predetermined time during reciprocation of the slides and swinging movement of the work holder.

52. The method of machining metal work, which consists in making a straight initial cut in the work, machining the work along one side of the initial cut, then machining said work from said side of the initial cut to the opposite side thereof, and thereafter machining the work along the last named side of said initial cut.

53. The method of machining metal work, which consists in making a substantially straightinitial cut in the work, machining the work along one side of the initial cut, then undercutting the work from said side of said initial cut to the opposite side thereof, and thereafter machining said work along the last named side of the initial cut.

54;. The method of machining recesses in metal work, which consists in making an in itial cut in the surface of the recess, and successively machining the recess surface along one side of the initial cut, undercutting a portion only of the wall of the recess, and machining the recess surface along the opposite side of said initial cut.

55. The method of machining tapered recesses in metal work, which consists in making an initial cut in the surface of the recess, and successively machining the recess surface along one side of the initial cut, undercutting the Wall of the tapered recess at the deeper part thereof, and machining said surface along the opposite side of said cut in. a direction opposite that of the first named machining operation.

58. The method of machining tapered recesses in cylinder heads, which consists in lli making an initial cut in the surface of the recess and successively machining the recess surface along one side of the initial cut from the shallower end of the recess toward its deeper end, undercutting the wall of the recess at its deeper end from saidside of the initial cut to the opposite side thereof, and machining said surface along the last named side of the initial cut from the deeper part of the recess toward the shallower part thereof. a

57. The method of machining metal work, which consists in simultaneously making a plurality of spaced initial cuts therein, and

machining the work in a plurality of curved,

paths produced by simultaneously cutting said work along corresponding sides of said initial cuts, then cutting the Work from said sides of the initial cuts to the opposite sides thereof, and thereafter cutting the work along the opposite sides of said initial cuts.

58. The method of machining tapered recesses in cylinder heads, which consists in making an initial cut in the recess wall, and successively machining the recess wall along one side of the initial cut, undercutting the wall recess at the deeper part of the recess, and machining said wall along the opposite side of said initial cut.

59. The method of machining tapered compression recesses in cylinder heads, which consists in making an initial cut in the recess wall, machining the recess wall along one side of the initial cut and the recess from the shallower part of the recess toward the deeper part thereof, and thereafter machining said wall along the opposite side of the recess and said initial cut.

60. The method of machining tapered compression recesses in cylinder heads, which consists in making an initial cut in the recess wall from the shallower part of the recess toward the deeper part thereof, machining the recess wall along one side of the recess and the initial cut, then undercutting the recess wall at the deeper part of the recess and at one end of the initial cut, and thereafter machining said wall along the opposite side of the recess and said initial cut.

61. The method of machining tapered compression recesses in cylinder heads, which consists in simultaneously making a plurality of initial cuts in the several recesses, machining the recess walls in one direction along corresponding sides of the recesses and the initial cuts, then undercutting the recess walls from said sides of the recesses and the initial cuts toward the opposite sides thereof, and thereafter machining the recess walls along the last named sides of the recesses and initial cuts in a direction opposite to that of the first named machining operations.

62. In an apparatus for machining recesses in cylinder heads for engines, a rotatable tool, a work holder adapted to support a cylinder head -;in' position i for the tool to imachi'ne out :a compression recess'inisaid cylinder" head, :and means for rocking the Work-holder and: cylinder head together in opposite directionsalong a curvilinear'path while the tool is in contact therewith, the

.axisabout which said curvilinear movement takes place being substantially perpendicular to the axis of rotationof said tool.

63. Inan apparatus for machining recesses in cylinder heads for engines, a rotatable tool, aworkholderadapted to support a cylinder head in position for the tool to machine out a compression recess in-said-cylinder head,

means for rocking the work holder and:cylinder head together in opposite directions along a curvilinear path while the tool is in contact therewith, the axis about which said curvilinear motiontakes place being substantially \perpendicularto the of rotation of said tool, and means for simultaneously rnoving said tool to and .fro in a direction parallel to said first named axis.

64. In an apparatus for machining cylinder heads for multi-cylinder engines, a plurality of rotatable tools, a work holder adapted to support a cylinder head in position for the tools to machine out a row of recesses in said cylinder head, and means for swinging the work holder in opposite directions along a curvilinear path during the machinmg operation, the axis about which sald curvilinear movement takes place being substantially perpendicular to the axes of rotation of said tools.

65. In an apparatus for machining cylinder heads for multi-cylinder engines, a plurality of rotatable tools, a work holder adapted to support a cylinder head in position for the tools to machine out a row of recesses in said cylinder head, means for swinging the work holder in opposite directions along a curvilinear path during the machining operation, the axis about which said curvilinear movement takes place being substantially perpendicular to the axes of rotation of said tools, and means for simultaneously moving the tools to and fro in a direction parallel to said first named axis.

66. In an apparatus for machining cylinder heads for multi-cylinder engines, a plurality of rotatable tools, a work holder adapted to support a cylinder head in position for the tools to machine out a row of recesses in said cylinder head, means for swinging the 67 In a machine tool, a work holder, a tool, means for advancing and retracting the tool with respect to said work, means for swinging the work while it is engaged with the tool, and means for traversing the tool parallel to the swinging axis of the work, all of said means being automatic in operation and the operation of each being coordinated with that of the others.

68. In an apparatus for machining recesses in cylinder heads for engines, a substantially vertical rotating tool, a work holder adapted to swing to and fro along a curved path beneath said tool, the plane of said swinging movement being substantially vertical, means for oscillating the work holder and. means for simultaneously traversing the tool in a vertical plane substantially perpendicular to the plane of said swinging movement.

In testimony whereof I have signed this specification.

HENRY KREBS.