US2496400A - Feed carriage control mechanism - Google Patents

Description

T. H. LJUNGGREN ET AL A A FEED CARRIAGE CONTROL MECHANISM Filed Oct. 1946 5 Shets-Sheec. i

N V T Q ill- Inveniors TEN? H Ljunugren LUiiiis F Mame W456 wwwmg 195 9 "r. H. LJUNGGREN ET AL y fi FEED CARRIAGE CONTROL MECHANISM Filed Oct. 4; 1946 Invmmrs Tim" Hl iungr mn films F. Mama At'h s 11 7 19% H. LJUNGGREN ET AL 24954@@ FEED CARRIAGE CONTROL MECHANISM Filed Oct. 4, 1946 s Sheets-Sheet 5 The?" H. Li ungfl w MM Ms F Mmm Patented Feb. 7, 1950 UNITED STATES PATENT OFFICE 2,495,400 FEED CARRIAGE CONTROL MECHANISM Vermont Application October 4, 1946, Serial No. 701,230 6 Claims. (01. 51-165) This invention relates to carriage feed mechanism by which devices such as electric switches may be actuated to produce a cycle change in the feed of the carriage, whenever the carriage reaches one or more predetermined feed positions, and has for one object to provide a construction which permits ready adjustment of the device actuating elements to accurate predetermined carriage positions and after accurate predetermined extents of feed from starting positions.

More particularly the invention relates to control of carriage feed mechanism for grinding machines in which the grinding wheel and the work are moved toward each other from a retracted relation at a rapid rate until they are near together but still out of contact, whereupon the rate of feed is reduced to a rate suitable for grinding feed, contact between the work and the wheel being effected while the feed is at the low rate. The grinding action may be divided into two phases, the first being rough grinding at a low rate, reducing the work to a size short of finished size, and the second, a finish grinding which completes the final sizing operation at a feed rate usually slower than the rough grinding rate, the wheel and the work being fully retracted between rough and finish grinding and after finish grinding. The rapid idle feed from the retracted position toward wheel and work contact may therefore be longer for finish grinding than for rough grinding because of the amount of work removed during the rough. grinding. The extent of rapid feed for rough and finish grinding is therefore independently adjustable in accordance with this invention.

For a complete understanding of this invention, reference may be had to the accompanying drawings in which Figure 1 is a fragmentary front elevation of a grinding machine embodying the invention Figure 2 is a detail sectional View to a larger scale on line 2-2 of Figure 1.

Figure 3 is a fragmentary view partly in side elevation and partly in central vertical section through the carriage feed mechanism.

Figure 4 is a detail sectional view on line 44 of Figure 2.

Figure 5 is a diagrammatic view of the work and grinding wheel showing diagrammatically the amount of stock removed in the rough and finish grinding portions of the cycle and the relative positions of the grinding wheel and work at which. the change from rapid idle feed to slow working feed takes place.

Figure 6 is a diagrammatic view of the feed mechanism and controls.

Referring to the drawings, at I is indicated a carriage which may support a work piece or a grinding wheel, or other tool, a grinding wheel being so shown in Figure 6 and the work holder being shown at 9 in Figure 5. This carriage has iournaled therein a lead screw 3 threaded into a nut 2 which is journaled in a, fixed portion of the machine frame. The nut 2 has fixed thereto a gear 4 with which meshes a gear 5 on a shaft 6. This gear 5 may have integral therewith a second gear I with which meshes a rack bar 8. By imparting axial motion to the rack bar 8, it will be evident that the gears I and 5 may be rotated, rotating the gear 4 and the nut 2, causing the lead screw 3 and the carriage to be moved axially of the lead screw.

Means may also be provided for rotating the lead screw with reference to the carriage, this imparting a selective feed motion to provide for wheel wear and truing. This additional means may comprise a worm I0 which may be brought into engagement with a worm wheel II carried by the lead screw 3. Also the lead screw 3 may have secured thereto, a hand wheel I2 by which it may be turned when the worm I0 is lifted out of engagement with the worm wheel I I. This means for feeding the Work carriage comprising the lead screw and nut is a micrometric feeding means actuable for feeding the carriage by accurate increments.

As shown best in Figure 2, the shaft 6 may have fixed thereto a disk I5, which, as shown best in Figure 1, may be graduated around its periphery, the graduations on the 'disk coacting with a fixed reference mark IT on the machine frame. By comparison of the scale readings on the disk opposite to the reference lin H, an accurate indication of the extent of feed motion imparted to the carriage as the disk is turned by the action of the rack bar 8 may be readily had.

The shaft 6 has journaled thereon a pair of arms 20 and 2|. These arms may be selectively secured at desired angular positions to thedisk I5. For this purpose they are shown as provided with thumb screws 22 and 23 which extend through arcuate slots 24 and 25 through the disk I5, these thumb screws being threaded into the arms 20 and 2|, respectively. On each side of the shaft 6 are arranged the electric switches 21 and 28 having actuating elements 29 and 30, respectively, and these actuating elements are arranged in the paths of motion of elements :.0f' the switches .54, 55 and 56.

shown as segmental pieces 3| and 32 which extend between the shaft 6 and the switch elements 29 and 30 and which at their forward ends have feet 33 and 34 which are secured to the arms 2! and 20 as by screws 35. In Figure 6 the shaft carrying the arms 20 and 2| is shown geared to the shaft 6. for. the .sakeof clarityof showing and may be actually so made if desired.

It will now be evident that as the carriage is being fed from a starting position, which-may be assumed as that where the .zero on the disk l comes opposite to the fixed indication ll, the arms and 2! are rotatediwith the disk until such time as one or the other of the segments 31 and 32 contact with and actuate their respective switches. As shown, for example, the arm 20 is arranged to contactitsswitch element after the disk has been turned twenty graduations, whereupon the switch 28 is closed, while further turning of the Idisk another ten graduaxtions-isnecessary to close the switch 21.

In Figure 6 the mechanism is shown embodied :imagrinding machinewith controls-of the type -more fully setzforthin an application for patent of Thor'i-H. .Ljunggren, Serial No. 701,443 :filed October 5, 1946, for Internal grinding -machine, wherein theva'rious phases of the-grinding cycle .are controlled by; a grinding cycle control mechanism-comprising a plurality of rotary switchactnated ,devices secured to a common shaft vwhich' isrotated step-by step to produce the de --sired: phase change of :the cycle. A portion of this cycle control, -mechanism is illustrated in Figure 6 comprising :a shaft carrying a plu- -rality of .disks' 5l,:52, and"53, each provided at 'lPUmtSI OH its periphery with projections which at" certain angular positions of the shaft 5% may close switches 54, and 56. .The rack bar 8, by motion of which the feed mechanism is operated; forms" the :piston rod of a piston '58 which rides ina fluid-.pressurecylinder 59 having pipes and-passages 6B and. Bi communicating with its interioron opposite sides of the piston .58. :-Moti0n of the piston 58 to the left from the position of Figure5 produces 'feed between the grinding wheel carried by the carriage l and the workf66 (see Figure 5), while motion of the :piston' 58 in'the opposite direction acts to retract the wheel from the work.

Controlof fluid pressure to and from the cylinder. 59 is provided by four valves '10, H, 72 and 13, each of which is normallyiin one axial posi- .tion, though it: may be moved to another axial position by energizing an actuating solenoid therefor :14, 15, 16 and 11, respectively, energizing. of these solenoids beingcontrolled by closing Fluid pressure .is supplied from a suitablesourcea pump being shown for the-purposataking hydraulic fluid from a tank 8! and-delivering it under-pressure -'determined by the setting of a relief valve 82 in .a discharge pipe83 leading back to the tank, the fluid being delivered at the predetermined .pressureto .a pressure-pipe 85. -A'discharge pipe -86 leads back to the tank 8 l Elec,tricalenergy for. energizing the various solenoids 14, .15, I6 and I1. is derived from the ;line--90,= this line leading through a lead 91 to the switches-54, 55 and 56. The line also leads to one terminal of the switch 2'! and also communicates through a lead 9| with one terrminal of a switch 92, this switch 92 being a safety switch. "The mechanism is. shown in Figure 6 as in its retracted position, the pressure pipe 85 It. through the pipe 6! leading to the left hand end of the cylinder 59, and the pipe 50 leading to the right hand end of the cylinder 59 leading past the valve H into a pipe 95 communicating with the drain pipe 85.

Assuming that a piece of work is in position in the work holder 9, and the. rough grinding operation is to be started, the shaft 50 is turned into the angular position to bring one of the projections on the disk 5| into position to close the switch 54,.and to bring one of the projections on the disk 53 into position to close the switch 56. Closing of the switch 54 energizes from the lead 9i and the switch 54, a lead H35 passing to one side of the rough grinding switch 28. The closing of the switch 56 energizes a lead ltl which energizes the solenoids 14 and 15, lifting the valve (0 and "H. Lifting oi the valve ll allows pressure'from the pipe 95 to pass the valve H into the pipe Gil leading to the right hand end of the cylinder .58, while the lifting of thevalve- Ill causes the pipe (ii to conduct d'mcharge pressure from the left hand end of the cylinder-59 past the valve 'lil:and into the pipe .l02, whichrleads to the valve 12. The switch 92.being closedwvhen the feed. carriage is in fully retracted position, energizes the lead I03 and energizes the-solenoid .76 so that the. valve 12 is in-.lif-ted position-as shown, the discharge-from thetpipe lll2then passing around the valve 12 through the pipe M4 to the valve Handout through the-pipe L05 containing a' throttle waive-106 to the main-drain pipe Jill leading-back to thetank ll'l. The deed mechanism then star-ts tomove to feeclthe-wheel toward the work, but-soonrafter this is done'the switch92 opens,.allowing the valve 12- to -drop so that-discharge takesplaee from-the pipe. I02 through the valve-I2 into the pipe. SIG-and, the drain pipe 36 without throttling. The feed thus after predetermined. delaying .action'of switch 32 is ata relatively rapid rate and this takes place until the cam 32. engagesand closes .theswitch 23. This takes place when thegrindingwheel G5 has moved toward the workup .to the .linea shown ,in Figure 5, atwhich point it is .not quite in contact with the work. As soon as this switch 28 is closed, the solenoid .15 is energized .irom the lead I00 through the switchZS, leads Mtand .103, this lifting the valve 12 and causing the discharge to take place through pipe lMpast the valve 73, through pipe I05 and through the throttle valve N36. The further feed between the wheel and the work up to the limit of rough grinding at the line b then takes place at the relative slow rough working feed rate. When this limit b is reached, the shaft 50 is turned a further distance so asto allow the switches 54 and 56 to open, conditioning the various valves, except the valve I2, in the positionv shown. in Figure 6, so that the carriage is retracted to its starting position. at which time the switch-=82 is closed, lifting the valve 12 so that all the parts except the shaft 50 and its disks is in'the position shown in Figure 6. At this point in the cycle, the wheel may be retracted and trued, as-is fully described in the Ljunggren application to-which attention has heretofore been called, but as this portion of the cycle is not concerned with the present invention it is not here shown.

Thefinish grindingoperation is then initiated, thisbeing done by rotating the shaft :50 until projections on the disks 52 =and-53 closethe -switches-55-and 56. Asbeforeznoted, closing of the switch'56 lifts thevalves' flfl and- 1|,=thus communicating through a pipe 95, past the valve .-.75 causing the piston tube-driven in feed-direction, and assoon as the feed starts the valve 12 drops so that the feed takes place at the rapid unrestricted rate. The closing of the switch 55 energizes the lead H5 which energizes the solenoid 'l'l, lifting the valve 13. This connects the pipe I04 past the valve 73 to the pipe I20, in which is placed the throttle valve I21, and after passing this throttle valve the fluid pressure flows to the discharge pipe I01. This throttle valve l2! may be set to restrict the flow more than the throttle valve I06 so that the speed of slow feed for finish grinding, as will later appear, is slower than the feed for rough grinding. The rapid rate feed continues until the cam 3| closes the switch 21, which, itwill be noted, is after the closing of the switch 28, but as during the finish grinding feed the lead 100 is not energized, switch 54 being open, nothing happens when the switch 28 is closed. When the switch 21 is closed, however, energypasses from the line 90 through this switch 21 and the lead I03 to the solenoid 16, which thereupon lifts the valve 12 into the position shown in Figure 6, whereupon the discharge from the left hand end of the feed cylinder 59 is compelled to go through the pipe I04, past the lifted valve 13, and through the throttle valve Hi.

It will be noted that the limit of fast feed in the finish grinding phase of the cycle may be beyond the limit of fast feed for the rough grinding, for the reason that the stock up to the line b was removed during the rough grinding. Limit of fast feed before the wheel can contact the work during the finish grinding may thus be at the point e, and from this point the wheel is moved with the slow finish grinding feed to the finish size position at d, at which point the feed is stopped by any suitable means, and the grinding operation has been completed.

The switch 92 has a delaying function of particular importance in connection with certain high rate production work. This switch is normally open, but it is held closed by the rack bar 8 when the rack bar is in the retracted position of Figure 6, so that the discharge from the cylinder 59 when the feed action is started, is throttled. After a short travel of the rack bar 8 toward the left, the switch 92 opens and the desired quick approach movement in transverse direction between the wheel and the work takes place. Because of the delaying action of the switch 92, the grinding wheel and the work have had time to arrive at approximately the relative overlapping axial positions of Figure before the wheel can contact with the work, so that any risk that the wheel will bump its corner against the corner of the work piece on entering the work is eliminated.

It will be noted that the rough and finish grinding actions alternate so that the switch actuating elements 3| and 32 become effective alternately, the cycle mechanism automatically selecting alternate switches to be effected during the feed actuations.

From the foregoing description of an embodiment of this invention, it should be evident to those skilled in the art that various changes and modifications may be made without departing from its spirit or scope.

We claim:

1. In combination with a movable carriage and micrometric means for feeding said carriage including a rotary shaft turnable through an angular extent proportional to the amount of feed of said carriage from a starting position, means for turning said shaft, a pair of switches located'on opposite sides of said sha'ft,-a disk fixed to said shaft, a pair of arms each pivoted on said shaft, means for selectively locking said arms independently to said disk in desired angular positions, and an element projecting from each of said arms between said shaft arid switches in position to actuate said switches on feed of said carriage to positions corresponding to the angular settings of said arms relative to said disk.

2. In combination with a movable carriage and micrometric means for feeding said carriage including a rotary shaft turnable through an angular extent proportional to the amount of feed of said carriage from a starting position, means for turning said shaft, a pair of switches adjacent to said shaft, a disk fixed to said shaft, a pair of arms each pivoted on said shaft, means for selectively locking said arms independently to said disk in desired angular positions, an element projecting from each of said arms between said shaft and switches in position to actuate said switches on feed of said carriage to positions corresponding to the angular settings of said arms relative to said disk, and means controlled by the actuation of one or the other of said switches depending upon whether rough or finish grinding is to be effected to slow the action of said feeding means.

3. In combination, a work support and a grinding wheel support, one of said supports comprising a movable carriage, means for moving said carriage to produce feed and retracting motions between a wheel on said wheel support and work on said work support, means including a pair of independently adjustable slow speed controls selectively made operative or inoperative for controlling the speed of such carriage motion in feed direction, means effective when said carriage reaches independently selectable positions in feed direction to render a correspondingly slow speed control effective for the remainder of such feed motion and means automatically controlling said carriage moving means to retract the carriage on the completion of each such feed motion.

4. In combination, a work support and a grinding wheel support, one of said supports compris ing a movable carriage, means for moving said carriage to produce feed and retracting motions between a wheel on said wheel support and work on said work support, means including a pair of independently adjustable slow speed controls selectively made operative or inoperativ for controlling the speed of such carriage motion in feed direction, means effective when said carriage reaches independently selectable positions in feed direction to render a correspondingly slow speed control efiective for the remainder of such feed motion, and means for selecting said controls alternately.

5. In combination, a work support and a grinding wheel support, one of said supports comprising a movable carriage, means for moving said carriage to produce feed and retracting motions between a wheel on said wheel support and work on said work support, hydraulically actuated means for moving said carriage to relatively feed and retract said wheel and work, a pair of independently adjustable flow limiting elements, means actuated automatically when said carriage reaches a predetermined position short of contact between the wheel and work when moving in feeding direction from a starting position during a rough grinding operation to interpose one of said elements into the hydraulic circuit with said vworking-speed and for interposing said other element at-, another predetermined position of said carriage short of contact between thewheel and work during the next feed which is a-finish grindingfeed of said carriage from said starting posi- :tion'to reduce the rate of feed to finish grinding iieedspeed.

- 6. In combination, a Work support and a grinding-wheel support, means for relatively moving said Supports to cause a wheel on said wheel sup- ,porhto ,move relatively axially to work on said work-1 support into and out of overlapping relation therewith and to traverse the Work, means or relatively moving said supports transverse to .saidaxial motion to feed said wheel relative to :the work-first at arapid rate from a retracted position toward the work and then at a slower rate into feeding contact and working feed, and

means for delaying the initiation of said rapid feed after the start of relative motion ofasaid wheel and work from retracted to overlapping relation to insure such overlapping relationbefore said wheel contacts the work.

THOR H. LJUNGGREN.

WILLIS F MOORE.

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

UNITED STATES PATENTS Number Name Date 1,673,078 Kempton et al. June 12, 1928 1,682,672 Guild Aug. 28, 1928 1,682,673 Taylor Aug. 28, 1928 1,949,511 Flygare Mar. 6, 1934 2,113,367 Belden et al. Apr. 5, 1938

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