US2886078A

US2886078A - Wood checkering machine

Info

Publication number: US2886078A
Application number: US644041A
Authority: US
Inventors: Crowe John
Original assignee: Olin Corp
Current assignee: Olin Corp
Priority date: 1957-03-05
Filing date: 1957-03-05
Publication date: 1959-05-12
Anticipated expiration: 1976-05-12

Description

May 12, 1959 J. CROWE woon CHECKERING MACHINE 6 Sheets-Sheet 1 Filed March 5, 1957 INVENTOR.

CR'OWE N H O J May 12, 1959 J. CROWE 2,886,078

' wooo CHECKERING MACHINE Filed March 5, 19's s Sheets-Sheet 3 IN V EN TOR.

JOHN CROWE BY f w J. cRowE woon CHECKERING MACHINE 4 E q o 5 W E m 0 i m R M, W C I o N 2 5 W (M a J \A ,v I D III m L 1 A 2. Q? D 2 (M y 9 N uh uh km. m E 3,

May 12, 1959 Filed March 5, 1957 J. CROWE wooo CHECKERING MACHINE May 12, 1959 6 Sheets-Sheet 4 'Filed March 5, 1957 W V F FIG-ll INVENTOR.

JOHN CROWE May 12, 1959 J. CROWE 2,386,073

' 4 WOOD CHECKERING MACHINE Filed March 5, 1957 s Sheets-Sheet s INVENTOR.

JOHN CROWE y 1959 J. cRowE 2,886,078

- WOOD CHECKERING MACHINE Filed March 5, 1957 6 Sheets-Sheet 6 WORK AREA NO-I FIG l6 WORK AREA NO2' B FIG-l7 ELECTRICAL CONTACT CAM I35 5 FOLLOWER SELECTOR SWITCH I43 |e7 V I66 I ELECTRICAL CONTACT CAM I34 ax FOLLOWER 142 r IRETURN STROKE C 3 Y SWITCH ma MAIN MOTOR SHUT DowN SWlTCH l63 Y Fl G [5 INVENTOR.

JOHN CROWE z M M United States Patent '0 2,886,078 a WOOD CHECKERING MACHINE John Crowe, St. Joseph, M0,, assignor to Olin Mathieson Chemical Corporation, a corporation of Virginia Application March 5, 1957, Serial No. 644,941 9 Claims. ((31. 144136) The present invention relates to checkering machines and in particular to automatic checkering machines adapted to checker gun stocks. The invention also relates to a process practiced by the operation of the ma; chine.

It is a particular object of the invention to provide an automatic machine adapted to receive a wooden or plastic work piece such as a forearm of a rifle or shotgun and to perform a cutting operation thereon in accordance with a predetermined pattern.

A particular object of the present invention is the provision of a machine adapted to receive a work piece and to carve at least two independent and separate areas thereof in automatic fashion and in sequence without any manipulation by anoperator.

A further object of the invention is 'to provide a machine of the above general character which, when set in motion, will accomplish in sequential fashion a variety of operations and which, upon the completion of the operations, will automatically shut down. r

It is astill further object of the present invention to provide a machinefwhose operation involves the practice of a novel process. i i

In general, a machine embodying certain principles of the present invention may include an arbor for supporting a work piece such as a walnut forearm of a gun stock and a circular milling cutter mounted adjacent the work piece and adapted to mill grooves therein. Means are provided for rotating and reciprocating the work piece with respect to the milling cutter so that, in effect, the cutter may be said to be generating a thread having a predetermined angle of lead. Since the work is rotated or oscillated through a predetermined arc while it is reciprocated axially, the cutter head is held stationary while accomplishing a single cut.

Automatic means are also provided for reversing the rotation of the work piece and for changing the angular position of the cutter head. This action is effective to cut grooves or threads, initially, with aHleft hand lead and thereafter with a right hand lead or vice versa. In this fashion, a knurled effect, known as checkering, is achieved on the surface of the work piece. In effect, a plurality of small raised portions having a diamond or pyramid shape are created.

Meansare also provided for controllingthe cutter whereby the cutter may be moved away from the work during certain intervals and thereafter moved towards the work so that the checkering falls withina predetermined area to define a desired pattern. t

As stated previously, the work piece is oscillated through a predetermined arc while it is reciprocated. Thus, if for the interval of each cut, one were to assume that the milling cutter mounting remains stationary, it is readily apparent that a single groove or thread will be milled inthe work piece as the work is oscillated and reciprocated simultaneously. It is tobeflunderstood that to accomplish a given out in the work piece, it is necessary for the work piece to rotate first in a r 2,886,078 Patented May 12, 1959 the work piece, the cutter being raised away from the work during return strokes.

Aftereach single out has been accomplished, means are provided for indexing the milling cutter head a predetermined distance along the work piece to provide new surface for milling a new thread.

After all cuts have been accomplished (having a lefthand or right-hand lead as the case may be) the milling cutter is shifted automatically to a new angular position with respect to the work and the oscillatory cycle of the work piece is reversed correspondingly so that there after threads or grooves of the opposite hand are milled. Means are provided for indexing the cutter in both axial directions so that the cutter first is indexed from left to right as vieWedinFig. 1 to make the first series of cuts of one hand and thereafter indexed from right to left to make the cuts of the opposite hand.

Usually a forearm is checkered in accordance with a desired pattern on opposite sides.- Accordingly, means are provided by the present invention for rotating the work piece automatically when a first side is completed to present the opposite side of the work piece to the milling cutter. "Thereafter the general operation just described is repeated automatically.

Ultimately when both sides oftthe work piece are completed, a counter means is effective toshut down the machine whereupon the operator may remove the finished work piece and recharge the machine.

The cutting head is also provided with a novel means for assuring uniformity of depth of grooves through- .out the full checkering pattern in spite of variations or tion will becomemore apparent from an examination of the succeeding specification and drawings, in which:

Fig. l is a perspective view of the complete machine;

Fig. 2 is a perspective view of thecutting head assembly; r I

Fig. 3 shows a, trigger and latch mechanism utilized to cast the cutting head from a right hand thread cutting position to a left hand threadlcutting position and vice versa; I i

Fig. 4 shows a flip-over or gear change device utilized to change the direction of rotation of the Work piece;

Fig. 5 is a perspective view of the cutting head indexingmechanism with certain portions thereof broken away; I

Fig. 6 is a view of the portion of the showing of Fig. 5 illustrating the'elements utilized to engage and disengage the indexing pawls;

Fig. 7. is also a viewof a portion of Fig. 5 showing to advantage the cooperation between the indexing pawls and the driving link therefor;

Fig. 8 is a perspective view of the cutting head yoke including the indexing racks and cam contactor;

Fig. 9 is an explodedview of the clutch mechanism;

Fig. 10 shows the. clutch actuating yoke;

Fig. 11 is a schematic showing of the arrangement of the contact cams, one contact cam being utilized to cut right hand grooves, thework piece and the other contact cam being utilized to cutthe left hand grooves;

Fig. 12 is a schematic showing of the angle through which thecutting headwis rotated when shifting from a right hand groove or thread cutting position to the opposite hand or vice versa;

Fig. 13 is ashowing 'ofthe counter device utilized to shut down the machine upon-thecompletion of -a-work piece; this device is mounted upon the back side of the machine as viewed in Fig. l;

- Fig. 14 is a similar view showing-the-counter 'device in the shutdowncondition.

Fig. is a wiring diagram utilized to control the checkering machine;

Fig. -16 is a schematic showing of therelative positions of the work piece and the cutting head while checkering is beingaccomplished in workarea-No. 1;

Fig. 17 is a similar showing of the same elements while checkering is being accomplished in work area No. 2; and j Fig. 18 is a vertical section of aportion of the cutting head of Fig. 2 as viewed in'the plane of'theline 'l8'18.

Referring'now to the drawings and in particular to Figs. lthrough 7, there-isshown a -main-support memher comprising a channel 10. Three mainvertical-supports 11, 12-and 13 are spaced along the channel 10. Supports 11 and 12 define,-in"general, the area'nwithin whichthe checkeringmachineis driven and controlled,

while the area of the-machine between

thesupports

12 and 13 is occupied by'the work piece and the cutting head.

-In the embodiment of the invention illustrated .in Fig. 1, the work piece is a wooden forearm of'a conventional firearm usually of Walnut and designated here by the reference numeral W.

Referring now in detail to the powerand control area of the machine defined bythe" vertical supports 'lland 12 and for convenience referred to hereinafter by the reference numeral 14, there is shown a main power sheave 16 connected toa gearbox 17. 'The'gear box supplies power to a crank 18 which, 'in'turn, reciprocates a lever 19. The lever 19 reciprocates a primary rack '21 which is in engagement with a gear sector "22.

The gear sector 22 is keyed to and carried by a stub shaft 23 supported on a vertical web member 24 suitably mounted upon the channel 10. Upon the opposite side of the web 24a stub shaft 23'carries anothergear sector 26 (shown in dottedlines) in'engagement with a sliding rack 27. It is to be noted that the gear sector26 is generally of the same diameter as the gear sector22; however, the stub shaft 23 also carries an additional gear sector disposed in thesame vertical plane as the sector 26 but of larger diameter. This latter sector, indicated by the reference numeral 28, is utilized to reciprocate the work piece W from right to left as viewed in Fig. 1 in a'manner which will become more apparent hereinafter,

Referring now in detail to Figs. 1 and 4, it is apparent that sliding rack 27 has a projection which engages still another gear sector '29. Sector 29 in turn engages and reciprocates a relatively short rack 31.

The short vertical rack 31 carries aflip-over or gear change 'device which is operable to cause the rack to drive one or the other of a pair of work rotating racks indicated hy the reference numerals 32 and 33 .respectively.

Short rack 31 carries a generally triangular-shaped rock lever 34 having oppositely disposed'arms36 and 37 respectively. The rock" lever 34 is pivotally mounted to the rack 31 by means ofthe pin 35 and'is also provided with a suitable spring pressed detent 38 eifective to encourage the rock 'lever.to. rock from the "position shown in Fig. 4 wherein the rotating rack132 is being driven to a secondpositioncorrespondingto a condition inpwhich, the rack 33 is being driven.

' his to be noted that a cross slide 39 is also mounted in the short rack and carries a pin 41 which engages a cooperating recess 42 in the rock lever. In this manner, whenthe rock lever'34 is'rocked to and fro in 'thedirections indicated by 'the arcuate arrow in Fig. 4,'fthe rock lever-by virtue of the cooperation of the'pin41 andthe recess 42 acts to cast the cross slide 39 from the position shown in Fig. 4 wherein the'tip 43 thereof is in engagement with a notch 44 formed in the rack 32 to a position wherein the tip 46 thereof will engage a corresponding notch 47 formed in the rack 33.

Thus, by virtue of the rock lever and cross slide carried by the reciprocating short rack 31, it is possible to cause the rack 31 to drive the rack 32 or the rack 33, in turn causing gear 58 to revolve clockwise or counterclockwise during the upward stroke of short rack 31.

The manner of accomplishing -flip-over of the'rock lever is as follows:

Asstated before, the rack 31, which carries the rock lever 34 and the cross slide 39, is constantly reciprocated vertically by the gear sector 29. The cross slide may be in driving engagement with either the rack 32 or the rack 33. It is also to be noted that there is suflicient clearance between the endsof a pair of guide bars 48 (rigidly mounted tozthe web 24 in a manner more apparent in'Fig. 1) to permit the rock lever and the cross "slide'to pass between the ends of the bars 48 and the face of vertical 'rack slides 49. A block' 51* rigidly mounted to the bars 48 carries a horizontal shift-lever 52 pivotally mounted to the blockiby a pin 53.

'The shift 'leverisipivotally connected to a timing rod '54 so that reciprocation of the ,timing rod alongthe path indicated 'bythe arrowsof Fig. will operate to rotate the shift lever. When the timing lever is withdrawn or moved to-the left as'shown in Fig. 4, a projection 56 of the shift lever is cast into'the path of the reciprocating rock lever'34 such that the arm36 of the lever is engaged bythe projection 56 and'the rock lever is cast to the left to the position shown in Fig. 4.

'Correspo'ndingly, the cross slide 39 is cast to the left and the tip 43thereoffinds its way'into the notch44 of the rack 32 thus making a driving connection between rack "31 and rack 32. After a predetermined interval and in sequentialfashion,-the 'timing rod 54 is automatically moved to the right as viewedin Fig. 14 thus placing a projection 57 of the shift lever 52 into: blocking ,position with respect to the blocking lug '37 of the rock lever. "When the projection 57'and'the lug 37 collide, the rock'lever is castto the right as viewed in'Fig. 4 causing the tip "46' of the cross slide39 to engage the notch'47' formed in the rack=33'. In this manner, power has been withdrawn from the rack;32 and applied to the rack 33.

Pinion v58, 'driven'for a predetermined interval by the rack32 and thereafter by the'rack 33, constantly oscillates through a predetermined arc and is carried by a main 'shaft"59 suitably journaled in the support '11. As will be apparent fromthe showing of Fig. l, shaft'59 runs the full length of the machine and rotates the work piece W through a corresponding arc.

T-hemain shaft 59 is suitably journaled in the support '12. and'in the support 13 .andalso carries a pinion 61 adjacent the support12 for driving a pair of cam "pinions '62 and"63 in a manner whichwill' become more apparent hereinafter.

"The shaft '59 carries a sleeve 64 slidably mounted 'thereonand formed on the underside thereof with a rack adapted .to engage the teeth of the large gear sector '28. Sincethe gear sector '28 constantly oscillateswith the stub shaft 23, 'the'sleeve'64 is caused to reciprocate to and'fro' al'origfthe shaft 59 whil'ethe shaft '59 rotates in oscillatory fashion. The sleeve64 is formed with an undercut groove or keyway 66 adapted to receive the ,headsi'67 of a pair.'(only one shown) of elongated'keys "68 slidablyreceived in the shaft 59 as is apparent at'69. It is to be noted that the keys68 are rigidly connected Ito the work W and function to cause the work to reciprocate'iin the -direction shown by the arrows of .Fig. 1 whilethewor k 'is oscillated through'a predetermined I ""fl fhereusjno jamm ng action with respect to 'the rethat if the work is moved relative to a stationary cutting element, a groove having a predetermined lead or a spiral is milled in the work piece.

For example, with the cutting head in the position shown in Fig. 1, and with the flip-over mechanism of Fig. 4 in the condition shown therein, the work piece W is rotated towards and away from the cutting head while it is moved axially along the axis of rotation so that a groove corresponding to the groove 61 is milled in the work piece.

Cutting head At this point it may be well to point out that the cutting head carries a circular milling cutter and means are provided for controlling physical contact of the cutter with respect to the work piece W so that the depth of cut may thereby be controlled and, too, so that the cutter is maintained clear of the work during the return portions of both the oscillatory and reciprocatory strokes.

The means for moving the cutting element into and out of engagement with the work will now be described. In this connection, a reference to Figs. 2, 8 and 18 will be helpful.

Thecutting head indicated generally by the reference numeral 71 is pivotally mounted upon a yoke 72 in turn pivotally mounted upon a plate 73. The cutting head 71. isso balanced in the yoke 72 that gravity tends to pull the left portion thereof, as viewed in Fig. 2, downwardly towards the work piece W. The plate 73 is secured to a pair of

feed racks

74 and 76 as is most apparent in Fig. 8. The racks, slidably received in slots formed in the underside of rigid bar 38, are utilized to move the cutting head along the work piece in a manner which will become more apparent hereinafter.

The forward portion of the cutting head is secured to an armature 79 integral with an electromagnet 81. The magnet, when energized, is operative to pivot the cutting head downwardly to aid gravity and to oppose a leaf spring. element tending to lift the cutting head away from the work in a manner which will become more apparent hereinafter.

For assuring the accomplishment of a uniform depth of cut a pair of

followers

83 and 84 are slidably mounted within a bracket 86 which in turn makes a lost motion connection with the cutting head wherein the bracket is pivotally supported by the pin 87. The bracket 86 is urged to move downwardly relative to the cutting head by a leaf spring 85 suitably secured to the cutting head and bearing upon a pin 90 supported in the bracket 86. A rigid bar 80 secured to the cutting head normally engages a projection 88a formed on the bracket 86 and is effective to limit the relative motion between the bracket and the head and thus between the cutting element 82 and the

followers

83 and 84. The position of the

elements

80 and 88a inFig. 18 represents their normal position and it is to be noted that normally the cutting element 82 is withdrawn with respect to the

followers

83 and 84. Although the followers normally ride upon the work piece, energization of the magnet .81 will'cause the armature 79 to pull the cutting head 71 downwardly causing the cutting element 82 to pivot about yoke 72. The force exerted by the solenoid is sufficient to overcome the tendency of the spring 85 to urge the cutting element upwardly with respect to the

followers

83 and 84 and as a result, the cutting element is moved to the dotted line position shown in Fig. 18. In this condition, the

cutting element is free to mill a groove in the work piece and the depth. of the groove is regulated by the prior set ting of the set screw 8812 with respect to a stop 880.

The pair of

followers

83 and 84 are slidably disposed in the bracket 86, as stated previously, and are carried by a cross pin 86a in turn supported by a rotatable pin90.

The axis of rotation of the pin. 90 is co-planar with the vertical plane which includes thegma'ximum diameter of the cutter. The pivotalmounting of the

followers

83 and 84 in conjunction with their ability to slide upwardly and downwardly assures a uniform depth of cut during the, occurrence of variations in surface contour or radius of the work piece. 1 i

It is to be understood that the followersactually ride on the work at all times; however, when the solenoid 81 is not energized the cutting element remains withdrawn above the lowermost portions of the followers therefore no cutting occurs even though the cutting element is rotating. Energization of the solenoid merely hauls the cutting element downward a predetermined distance beyond the lowermost portions of the followers and cutting occurs.

v Indexing As stated previously, means are provided for indexing the cutting head in incremental fashion along the workpiece W after each cut has been completed.

Referring again to Figs. 1, 2, 5 and 8, it is apparent that the cutting head slides along a rigid bar 88.wherein feed racks 74 and 76 are provided with extensions which carry the cutter yoke 72. Feed rack 74 is utilized to index the cutting head from left to right as viewed in Fig. 1 while feed rack 76 is utilized to index the cutting head from right to left. A timing bar is provided for placing one feed rack or the other in operation and correspondingly rendering the other inoperative in sequential fashion. The power for the indexing mechanism is pro-. vided by sliding rack 27 (Fig. 5) wherein one end thereof is provided with a cross pin 89 straddled by a pair of feed levers 91 and 92.

A reference to Figs. 5, 6 and 7 will make this structure more apparent. Note that the elementsare shown as viewed from the opposite side of the showing of Fig. 1. j The feed levers are pivotally mounted individually to the vertical support 12 as at 93 and each carries a pivr otally mounted pawl or dog 94. Each dog is adapted to engage a corresponding rack and are effective to advance the cutting head a predetermined distance in one direction or the other, depending upon which dog is engaged, asthe slide rack 27 is reciprocated.

.The dogs. are brought into and out of engagement with their corresponding racks by a pair of rock levers 96 pivotally mounted to the vertical support 12 and actuated by a timing bar. 97.. Each rock lever is provided with a projection 98 which cooperates with a pin 99formed on each dog.

As is apparent in Fig. 6, rotation of the rock lever in thejdirection shown by the arrow will cause the projection 98 to contact the pin 99 thereby camming the dog upwardly out of engagement with its corresponding rack. Both rock levers are generally of the same construction, however, the projections 98 are [formed on opposite sides thereof so that when the timing bar 97 pivots therock levers, one lever operates to drop a dog into engagement with its corresponding rack while the other lever operates to disengage the opposite .dog from its rack.

- Timing bar 1 As is apparent, a great number of mechanical operatrons occur automatically in the course of checkering a work pieceutilizing the machine of the present invenhas a projection thereof in the form of a rod 54 extending towards vertical support 11. It will be recalled that the timing rod 54 was discussed in connection with the operation'of the'flip-over mechanism for changing rotation of the workpieces The connection between the timing rod 54 and the timing bar 97 is accomplished through the instrumeutality of the rock levers 96 as w1ll I be apparent inFig. 5.

The timing bar contains an elongated slot 101 engaged by a depending lug 100 mounted upon the cutting-head. The timingbar andits accompanying rod are shifted in the direction of the arrows shown in Fig. 2 by the engagement of the lug 100 with the corresponding end of the slot I01'as the cutting head is indexed to its extreme right-hand or left-hand positions as viewed in Fig. l. The timing bar 97 and its. extension 54 control 1) the gear change or flip-over mechanism (2) the actuation of selector switch 143 and (3) the engagement and disengagement of the indexing pawls or dogs Reversal of angular position of 'cutting head As is apparent in Fig. 12, the cutting head is first disposed with respect to the work piece W in a first angularposition. While in this angular position, the cutting head is indexed after accomplishing each out along the full length of the desired pattern accomplishing a plurality of parallel cuts. Upon completion of these cuts, the head is automatically shifted from a position indicated in Fig. 12 by the reference numeral 102 to a position indicated bythe reference numeral 103 and a new series of parallel cuts are accomplished making an included angle of approximately 55 degrees with respect to the cuts formed by the previous position 'of the cutter.

Incidentally, it is to be noted that "at the time of occurrence of the shift of the cutter fromposition 102 to 103, the cutting head has actuated the timing bar to cause the indexing mechanism to shift from one indexing rack to'the other.

A reference to Figs. 2 and 3 will reveal the mechanism that is utilized in accomplishing the angular shifting of the cutting head. Fig. 3 is a perspective view of the underside of the head support and for purposes of explanation, the plate member 104 may be considered integral with theyoke element 72. These members are both pivotal "about the pin 106 and are connected by the post 107-. The plate 104 is formed with a finger 108 disposed between a pair of Cooking springs 109. The plate also carries a pair of "oppositely disposed notches lllengageable by corresponding pivotally mounted triggers 112. As the cutting head assembly approaches an extreme position marking the end of a predetermined group of parallel cuts, a spring housing 113 slidably mounted in.

the bearings 1 14 encounters a stop or an abutment such as the abutment 116. Continued indexing of the cutting head causes the spring housing to slide through the'bearings 114 thus compressing the adjacent cocking spring 109 against the finger 108. The plate 104 is held against rotation about the pin 106 wherein the trigger 112 and the corresponding lug 111 are latched in the manner shown in Fig. 3. 1

Further indexing of the cutting head towards the end of its run moves the latched trigger 112 towards another abutment such as the abutment 117. Up'on contact the dog is unlatched=and the compressed cocking spring 109 operates to rotate (in the direction of the arrow of Fig. 3) the plate 104 including the yoke 72 and the cutting head through an angle of approximately 55 degrees or to the position shown by the reference numeral 104 in Fig. 12. At this time, the opposite trigger andits corresponding'not'ch 111 latch the cutting head firmly in positi'on. a

It is t' 'o be understood that the

abutments

116 and 117 respectively are mountedupon the vertical upport 13 arfdthat corresponding 'a'bu'trnents are provided upon the Turning the workpiece As stated previously, it is frequently desirable to checker a given pattern on one area of a work piece and thereafter checker the same pattern on the opposite side; consequently, the checkering machine of the present invention includes means for automatically turning the work piece W from a first work position to a second work position for the purpose of forming an identical pattern in at least two different areas.

' Referring now to Figs. 1, 9 and 10, it will be apparent that the main shaft 59 is provided with a clutch indi cated generally by the reference numeral 118. The clutch comprises a driving element 119, a driven member 121 and a locking member 122. An operating yoke 123 is formed with an arcuate portion 124 adapted to engage an undercut portion 126 formed on the locking member. The yoke is pivotally mounted to the block 51 and carries a pair of operating arms 127 having cam surfaces 128 formedon the undersides thereof and engagerespect to the driving member 119 wherein the lugs 131 are moved beyond driving surface 132.

During the moment of disengagement, a' suitable coil spring (not shown) is free to cause the driven member 121 and locking member 122 to rotate or to be phased approximately 180 degrees with respect to the driving member whereby the lugs 131 encounter stops 133. The stops limit the phasing to 180 degrees.

During this occurrence the timing bar 97 hasbeen actuated by the lug (Fig. 2) depending from the cutting head to cause the indexing to be reversed so that upon the next stroke of the slide rack 27 the follower 129 moves away from the cam surface 128 permitting the yoke to return the locking element 122 into a driving connection with the driving element 119.

A second predetermined work area,.namely, the opposite side -of the work piece W having been presented to the cutting head, the machine automatically begins to perflgrm cutting operations upon this new area of the wor A more detailed explanation of the sequence cutting operations will be presented hereinafter.

Electrical control cams As stated earlier, electrical means are provided for controlling the checkering pattern. This is accomplished by sending an electrical signal to the cutting head solenoid which is eifective to cause the solenoid to pull the cutting element into the work at a predetermined time interval permitting the cutting element tomill a groove of predetermined length as the 'work is rotated and oscillated and thereafter the signal operates. to dee-n'ergize the cutting head solenoid effective to terminate cutting, thereby limiting the length of groove'and permitting the work to accomplish its return stroke without engaging the cutter.

Obviously, the parallel grooves formed while the cutting head is in the position represented by the reference numeral 103 in Fig; 12 and those of the opposite band formed when the cutting head "is in the position designated by the reference numeral 102 inFig; '12 must be con-trolled so that'the ultimate configuration or outline of checker-lug falls within a predetermined are'a.

For example, a pattern on work piece W shown in Figs.

7 l and 12 is representative of such an outline.

In order to control the cutting element and the cutting head to accomplish the desired pattern, four contact cams are provided.

For reasons that will become more apparent hereinafter the electrical contact cams are provided in pairs,

one pair effective to control the grooves formed while the cutting head is in the position represented by the reference numeral 102 and the other pair eifective to control the grooves milled when the cutting head is in the position represented by the reference numeral 103 of Fig. 12. e p

Referring now to Figs. 1, 8, 11 and 12, the pairs of contact cams are designated by the

reference numerals

134 and 135 mounted on

shafts

136 and 137 respectively in turn supported for rotation in the vertical supports 11 and 12.

It is noted that the shafts carry pinions 62 and 63 in driving engagement with main shaft pinion 61.

Since the function and structure of each pair of cams is substantially identical, the structure and operation of only one pair thereof will be described in detail, it being specifically understood that one pair of cams is utilized whenever the cutting head is in the angular position represented by the reference numeral 102 while the other pair of cams is utilized when the cutting head is in the 103 position.

It is noted that each pair of cams take the form of a split cylinder and in the case of contact cams 135 comprising an arcuate electrical contact of brass or copper 138 and another, referenced 139. Current is passed through these contact cams to a contactor 141, in the case of pair 135, and 142, in the case of pair 136 (Fig. 8), in a manner which will become more apparent hereinafter. The cams are in circuit with the solenoid 81 which controls cutting head. The configuration or outline of each cam is formed in accordance with the pattern desired to be cut upon the work piece W. For example, as the work piece is rotated, the contact cams will be rotated whereby the arcuate cam 138 or 139, depending upon the phasing of the work piece W, will sweep past the contactor 141.. Whenever the cam surface engages the contactor, current will flow into cutting head solenoids to pull the, cutting element into the work. When the contact cam sweeps past the contactor 141, the circuit is broken and the cutting head is immediately re leased from the work. t

. It is to be noted that the contactors 141 and 142 are mounted upon the feed rack; consequently, they are in dexed along the contact cams, simultaneously with the indexing of the cutting head. r

Pairs of contact cams (such as the segments 138 and 139) of generally identical configuration are provided on each

shaft

136 or 137 so that when the work piece is rotated from the first work area to the second work area as described under that portion of the specification entitled Turning the Work Piece above, a contactscam will be available for controlling the cutting head in each position of the work piece. As stated before, the pair of contact cams individual to a given shaft control the cutting head while in a given angular position such as represented by the reference numeral 102 while the other pair, of electrical contact camscontrol the cutting head while in the opposite angular positiondesignated by the reference numeral 103.. l 1

Current is provided to the contact cams by means .of conventional brush and commutator arrangements mountedonthe

shafts

136 and 137. A cut out switch is provided for breaking the electrical circuit to the brushes in a manner which will be more apparent hereinafter.

By the same token, the current flow through a particular pair of contact cams 133 or 134is controlled by a selector switch 143 (see Fig. 1) actuated by the cutting head carriage.

10 Timing Ina typical cycle of operation, the cutting head and the work piece assume'the following positions in sequential fashion and the checkering machine correspondingly forms a variety of operations automatically. A reference to Figs. 16 and 17 will show schematically the sequence of these positions. In Fig. 16 the work piece W is shown positioned with the first work area presented to the cutting head. Assume that the cutting head is disposed in position A. Operationof the checkering machine will cause the work piece W to rotate and reciprocate so that a groove ismilled in the work piece in the direction shown by the arrow. Obviously, the length of the grooves is controlled by the action of the particular electrical control cams corresponding to position A. and to work area No. 1, i.e., cam segment 138 of pairs 135. The cutting head will be indexed along the work piece in the direction shown by the horizontal arrow of Figs. 16 until ultimately the final groove is milled. Upon completion of the last groove the angular position of the cutting head will be reversed simultaneously with the reversal of the direction of rotation of the work piece so that thereafter the cutting head will be in angular position B and the cutting element will begin to mill grooves along the new angular position; the grooves being milled in the direction shown by the arrow. 1

Obviously, when the cutting head is in position B, the control cam corresponding to the angular position and to the particular work area, is in circuit with the cutting head solenoid, i.e., the timing bar 97 actuates selector switch 143 to place the proper cam segment of the pair of segments 134 in circuit with the magnet 81.

While in position B the cutting head will be indexed in incremental fashion along the work piece until ultimately the desired number of parallel grooves are complete in accordance with the signals controlled by the corresponding electrical contact cam. At this point the clutch is disengaged by the action of the lug 129 upon the cam surface 128 (see Fig. 10) whereupon the clock spring (not shown) causes phasing or rotation of the work piece through degrees to present work area No. 2, represented by the showing of Fig. 17, to the cutting head. While the work piece is being rotated to work area No. 2, the cutting head is flipped from angular position B to angular position A by the operation of the trigger and latch mechanism of Fig. 3. Furthermore, the direction of rotation of the work piece isalso reversed by the operation of the gear shift device of Fig. 4. Thereafter the work piece W is in the position shown in Fig. 17 while the cutting head is in angular position A and the checkering operation proceeds as described in connection with Fig. 16. Thereafter and upon completion of the desired number of threads or grooves from the A position the head shifts automatically to angular position B; work rotation having been reversed and the series of grooves corresponding to the B position of the cutting head are milled.

Upon completion of work area No. 2, a counter mechanism to be described hereinafter is effective to shut down the checkering machine whereupon the work piece may be removed and the machine reloaded.

Counter mechanism Referring now to Figs. 13 and 14, there is shown a counter mechanism comprising a pivotally mounted dog 146 having an operating arm 147. The dog is pivotally mountedto a bracket 148 in turn secured to the channel 10. A coil spring 149 urges the dog into engagement with rotatable lug 151 having a plurality of

projections

152, 153 and 154. Coil spring 149 constantly urges the dog 146 in the direction tending to engage

lugs

152 and 153. Cooperating with the rotatable lug 151 is stop lever 156 having a hook portion 157 adapted to engage projection 154.

When the lug 151 is inthe position shown in Fig. 14 the stop lever rotates in the direction shown by the arrow in response to theurging of a spring 150 wherein the hook 157 and the projection 154 are engaged. When this rotation occurs, a pin 158 mounted in the upper regions of the stop lever assumes a blocking relationship with respect to a crank arm 159 rigidly secured to stub shaft 23 thus blocking further operation of the machine.

Simultaneously, the opposite end of the stop lever 156 carrying a pin 161 in turn engages a U-shaped switch operating element 162. Consequently, when the stop lever 156 assumes its blocking position the element 162 is moved to the right as viewed in Fig. 14 with the result that a switch 163 operates to open the electrical power circuit to the checkering machine thus shutting it down.

The counter mechanism is operated by the contact of a lug 164 projecting from the underside of the indexing rack 76.

When the cutting head is in position B, the rack 76 is indexed constantly to the right as viewed in Figs. 13 and 14 until ultimately the lug 164 contacts the operating arm 147. When this occurs, the arm 147 is rotated in the direction shown by the arrow and the dog slides to the left and over the lip of lug 152. When the cutting head returns to the left, spring 149 causes the dog 146 to rotate the lug 151. 1 V

The counter action occurs for the first time upon the completion of work area No. 1 and corresponding counteraction occurs upon the completion of work area No. 2 wherein the dog 146 engages projection 153 to rotate the lug 151 into a position to receive hook 157 into engagement with projection 154 whereupon switch 163 is opened and operation of the machine is blocked as shown in Fig. 14.

Electrical circuit Referring now to Fig. 15, there is shown schematically the electrical circuits for controlling the operation of the checkering machine of the present invention.

Current is supplied from a suitable source of power through the lead 166 to the selector switch 143. From the selector switch, depending upon the position thereof, current flows through electrical cam 135 and follower 141 to the junction 167. Of course, if the selector switch is in the opposite position current will flow alternatively through electrical contact cam 134 and follower 142 to the junction 167. These two current flow paths correspond to 1) the A and A angular position of the cutting head in one case and (2). the B and B angular position thereof in the other case.

In other words, when the cutting head is making grooves from the A or A positions depending upon which work area is presented to the cutting element, current is flowing through the electrical contact 135 and follower 141 while when the cutting element is making grooves from the B and B' position current flows to the electrical contact cam 134 and corresponding follower 142.

It is to be understood that when each follower and its corresponding cam are in contact, current flows and that when the contour of the cam is such that there is no physical contact between the two elements, current does not flow in the respective circuits.

From junction 167 current flows through a return stroke switch 168. This switch is located on the main drive sheave 16 and takes the form of a circular commutator segment having a conducting segment of approximately 180 and a non-conducting segment through the remaining 180. The angular position of this commutator is so phased with respect to the reciprocatory and oscillatory rotation of the workpiece W that during the return reciprocatory and oscillatory strokes the electrical circuit is broken so that there is the assurance that the cutting head magnet will be de-energized and the cutting element correspondingly raised out of contact with the work piece.

A reference to Fig. '16 will provide clarification of the function of this switch. Assume that the cutting head is in the position A and that the: corresponding electrical contact cam and follower having. come into physical contact. The cutting head will be pulled into the work and a groove will be milled in the direction of the arrow as work piece W is reciprocated from left to right and rotated towards the cutting element. When the reciprocatory stroke has been completed to the left and the rotational stroke has been completed in a direction toward the cutting element, the work piece traverses return strokes to the starting point. It is during this latter interval, corresponding to the return strokes and actual indexing of the cutter that current to the cutting head solenoid 81 is divered by the return stroke switch 168, thus assuring that the cutting element remains raised out of contact with the work piece.

From the return stroke switch, current flows through the shut down switch 163 normally in a closed position until the counter mechanism operates to break the circuit in a manner previously described. Thereafter currentflows through the winding of the cutting head solenoid 81 and thence back to the other side of the line.

It is to be understood that the cutting head motor is energized by a separate circuit and the cutting head motor is maintained in operation constantly.

Loading and unloading the work piece The work piece W is inserted in the checkering machine by dropping the upper portion 171 of the vertical support 13 about hinge pin 172 in the direction shown by the arrow of Fig. l. Thereafter the work piece is removed from the shaft 59 by sliding it axially along the shaft to the right. A new and uncheckered piece may thereafter be inserted by performing the above steps in reverse. It is noted that the shaft 59 in the area where the work piece is reversed is formed with an arbor having the general configuration of the interior of the work piece, thus assuring that the work piece is adequately keyed against relative rotation with respect to the shafts.

Operation Assume that the checkering machine has been loaded with a work piece W and that the cutting head is disposed in position A ready to begin checkering work area No. 1 as shown in Fig. 16. Prior to starting the machine it is necessary to disengage the clutch and wind the clutch spring manually so that upon completion of work area No. 1, the shaft 59 will be automatically phased through 180 with respect to the driving shaft.

It is also necessary to set the counter mechanism in the position shown in Fig. 13.

Thereafter the machine may be set in operation by suitably driving the sheave 16 whereupon the work piece W will begin to reciprocate and to rotate in oscillatory fashion. As the work piece rotates toward the rotating cutting element and moves to the left as viewed in Fig.

16, contact 141 also begins to scan cam segment 138 of the pair of cams 135. When physical contact between these two elements occurs, current flows to the cutting head solenoid 81 causing the cutting element to be pulled into the work piece. When the length of cut is signaled by the breaking of physical contact between the

elements

141 and 138, the cutting element is withdrawn from the work and the work piece continues to rotate towards the cutting head and to reciprocate to the left and until the ends of the respective strokes are reached.

At this instant, return stroke switch 168 becomes operative to open the electrical circuit to magnet 81 and the circuit remains open during the complete return stroke of the work piece in spite of the fact that contact 141 will physically sweep over cam-segment 138 in the course of the return stroke.

As soon as the first cut is complete, the appropriate feedv rack and pawl, such as the rack 76 and the pawl 94,

are operative in response to slide rack 27 to index the into position A in the first instance.

cutting head a predetermined distance along the work piece. The appropriate driving rack has been placed in driving condition, by the operation of the timing .bar 97 in conjunction with rock levers 96, the timing bar, of course, having been set by the engagement of the lug 100 with the 'end of the slot 1 01 asthe cuttinghead' swung The cutting head] is indexed alongthe work piece in incremental fashion until all grooves have been milled from position A. I This occurrence is signaled by the engagement of depending lug 100 with the timing bar,

specifically the opposite [end of slot 101. Correspondingly, the trigger and latch mechanism of Fig.3 are operative to cast the cutting head from position A toposition B. During this occurrence the lug 100drives the timing bar 97 to the left with positive motion and the timing bar, in turn, operatesto (1) actuate the selector switch 143 to place the appropriate cam in circuit (2) actuates the gear change or flip-overmechanism'through the instru- A. Upon the completion of all cuts from the B position,

the cutting head is automatically shifted to the A position; the selector switch shifts the current to the opposite pair of. contact cam segments, the gear change device is actuated to reverse rotation of the work piece, the appropriate end rack is engaged while the other is disengaged in generally the same fashion as the occurrence of these events previously described .witbrespect to the shifting of the cutting head from position A to position B. There is, however, one additionaloccurrence at this moment; namely, the clutch 118 is actuated by the lug 129 to permit the work piece to be phased through 180 so as to present work area No. 2 to the cutting head.

Thereafterithe machine proceeds automatically to perform the function and operation described with respect to Fig. 16.

During the course of the operation of the checkering machine, the counter mechanism of Figs. 13 and 14 is operative in the manner previously described until ultimately, upon the completion of work area No. 2, the

counter mechanism is rendered operative to shut down i the machine thereafter the complete work piece W is removed and a new piece inserted. Repetition of the above described operations may then be undertaken to checker the new work piece.

It is anticipated that various modifications and arrangements may be undertaken as design considerations and engineering practices may dictate without departing from the spirit and scope of the present invention.

What is claimed is:

1. An automatic checkering machine comprising an arbor movably mounted in a frame for supporting a work piece, a cutting head mounted in the frame and movable from a normal position to a cutting position effective to cut grooves in the workpiece, means for indexing the cutting head along the work while in the normal position,

means for rotating and reciprocating the arbor and thus the work simultaneously with respect to the cutting head so that the cutting head while in the cutting position mills grooves of a predetermined hand and angle of lead in the stock, a first control means. operable to move the cutting head from the normal position to the cutting position in accordance with a predetermined pattern and a second control means including a pair of relatively movable followers cooperating with the cutting head and the surface of the work piece effective to insure a uniform depth of out throughout the pattern.

2. An automatic checkering machine comprising an arbor movably mounted in a frame for supporting a work piece, a cutting head mounted in the frame and movable from a normal position to a cutting position to cut a plurality of grooves in the work, means for indexing the cutting, head along the stock after each groove iscut, means for rotating and reciprocating the work simultaneously with respect to the cutting head so that the cutting head while in the cutting position mills grooves of a predetermined hand and angle of lead, automatic means controlled by the indexed position of the cutting head for shifting the cutting head and shifting the motion of the workpiece whereupon grooves of the opposite hand are milled, a first control means operable to move the cutting head from the normal positionto the cutting position in accordance with a predetermined pattern and a second control means including a pair of relatively movable followers cooperating with the work piece and the cutting head effective to insure a substantially uniform depth of out throughout the pattern.

3. An automatic checkering machine comprising a shaft movably mounted in a frame for supporting a work piece, a cutting head movably mounted in the frame and normally spaced from the work piece, means includingan electro magnet effective to move the cutting head towards the workpiece into a cutting position, means for moving the shaft and thus the work with respect to the cutting head so that the cutting head while in the cutting position mills a groove of a predetermined hand and angle of lead in the stock, electrical control means effective to regulate the electro magnet so as to control the length and continuity of said groove, and mechanical control means mounted upon the cutting head and including at least two relatively movable followers engageable with the work piece effective to insure substantially uniform depth of groove.

4 An automatic checkering machinecomprising a frame, a work holder rotatably mounted in the frame and adapted to support a generally cylindrical work piece along its longitudinalaxis, said work holder having a first working position and a second working position, acutting head movably mounted on the frame, means for reciprocating and for rotating the work piece simultaneously while in said first position, means for positioning the cutting head relative to the work piece so that while the work piece is rotated and reciprocated in said first position a threadof a given hand is milled in the work piece, means for indexing the cutting-head along the work automatically after said thread is milled, automatic means responsive to the indexed position of the head operable to reverse the direction of rotation of the work piece and to change the position of the cutting head whereby a thread of the opposite hand is milled, cam means including an 'electromagnet effective to tilt the cutting head to and fro with respect to the work piece to control the length and continuity of each thread and automatic means for shifting the work piece from said first working position to said second workingposition so that a new area of the work piece may be checkered.

5. An automatic checkering machine comprising a frame, a work holder rotatably mounted in the frame and adaptedto support a generally cylindrical work piece along its longitudinal axis, a cutting head movably mounted on theframe, means for advancing and for rotating the work piece simultaneously, control means for positioning the cutting head relative to the work piece so that while the work piece is rotated and advanced a thread of a given hand is milled in the work piece, means for returning the work piece to its starting point, said control means being etfective to tilt the cutting head away from the work piece during the return stroke", meansfor indexing the cutting head along the work automatically after each thread is milled, automatic means responsive to the indexed position of the head and operable after a predetermined number of threads have been milled to reversethe direction of rotation of thework piece and to yhange the position of, the cutting head wherebythreads of the oppesitehand are milled, andjcam means cooperating with the control means effective to control the length and continuity of each thread of both hands whereby apa-ttern of checkering having a predetermined an n i f m d- A machine for automatically checkering a gun stock comprising a fr ame, a work holder supported in the frarne and adapted to support a gun stock generally along its longitudinal axis, a cutting head mounted on the frame, means for moving the cutting headinto engagement the stock, means for rotating and advancing the stoc k simultaneously while the cutting head is in engagement with, the stock effective to mill a thread in the kfmeans for indexing the cutting head along the stock automatically for milling a plurality of said threads, automatic means responsive to'the inderring means for reversing the direction of said rotation and for changing the position of said cutting head whereby threads of the opposite hand are milled, andlcam means including an electromagnet effective to control the interval during whichitheicuttmg head is held in engagement with the stock While cuttingla given thread, means for turning the'stock automatically upon completion of a first checkering operation inatfirst area of the stock to present a new area to the cutting head and counter means responsive to the indexing mechanism operative automatically to shut down themachine after said new area has been checkered. i i

.7 A machine for automatically checkering a wooden work piece comprising a frame, a work holder movably supported in the frame and adapted to support the work piece generally along its longitudinal .axis, a cutting head mounted on the frame, means for moving the cutting head into engagement with the work, means for rotating and advancing the work simultaneously while the cutting head is in engagement with thework eifective to mill a thread in the stock, means for moving the cutting head out of engagement with the work, means for returning thework piece to its starting point, ratchet means for indexing the cuttinghead along'the stock automatically for milling a plurality of said threads, automatic means including a timing bar responsive to the indexed position of the cutting head for reversing the direction of said rotation and for changing the position of said cutting head whereby threadsof the opposite hand are milled, and cam means including anelectromagnet effective to control the interval during which the-cutting head is held in engagement with the work while cutting a given thread, means to the indexing means and'operatiye automatically to shutdown the machineafteiia predetermined number of areas have been checkered. p 4 E t Y 8. A machine for automatically checkering a gun stock comprising a frame, an arbor carried by the framefor movablysupporting the stock, a cutting head movably mounted in the frame and adapted to cut grooves in the stock, means for moving the stock with respect tofthe cuttinghead and the cuttinghead relative to the stock so that the headmills at least two groups of grQOYes therein, each group having a predetermined hand'and angleof lead, control means operable to limit thelength and continuity of each groove in accordance with apr edetermined pattern and at second controlmeans including at leasttwo relatively movable followers cooperating with 'thecutting head and the surface ofthe workpiece effective to insure a uniform depthof cut throughoutthe pattern. i v i 9. In a wood checkering machine includingfa work holder and alcutting head carrying a cutting element, a device formaintaining uniformity of depthof'cut in a :WOIk piece carried by the work holder where cutting occnrs while the work piece and the cutting element move relative to one another comprising: a pair of followers movablymounted upon the cutting head and normally disposed in sliding contact with the surface of the vwork piece while the cutting element normally projects a predetermined distance beyond'the followers into the work, saidlwork piece'having variationsin its surface contour characterized by high and low regions, said followers being movable relative to one another along paths generally normal to the surface of the work piece so that both followers remain in contact with the work as the followers encounter said high and low regions, said predetermined distance remainingsubstantially constant with 2,543,405 2,573,565 ,Hailston et all 1 Oct. 30, .1951 2,638,946 McDonald et al'. -May19,

V FOREIGN PATENTS 949,845

France Mar. 7, 1949