US2923106A

US2923106A - Grinding machine

Info

Publication number: US2923106A
Application number: US755075A
Authority: US
Inventors: Peter U Reusser
Original assignee: Heald Machine Co
Current assignee: Heald Machine Co
Priority date: 1958-08-14
Filing date: 1958-08-14
Publication date: 1960-02-02
Anticipated expiration: 1977-02-02

Description

Feb. 2, 1960 P. u. REUSSER 2,923,106

GRINDING MACHINE Filed Aug. 14, 1958 4 Sheets-Sheet l 25/ v l l 3a 5: fl 39 b E -4z l5 46 mmvrox Peter ll. ReLlSSeT haw Feb. 2, 1960 P. u. REUSSER 2,923,106

GRINDING MACHINE Filed Aug. 14, 1958 4 Sheets-Sheet 2 INVENTOR. Pete? ll. Reusser Feb. 2, 1960 P. u. REUSSER 2,923,106

GRINDING MACHINE Filed Aug. 14, 1958 4 Sheets-Sheet 3 INVENTOR. Peter U. Reusse'r agg Feb. 2, 1960 Filed Aug. 14, 1958 Sheets-Sheet 4 0-D 0-D. [.D. WHEEL WoRKPIECE COMP. FEELER REF. FEELER FEELER UNCLAMPED RETRACTED m g 555 IN OPERATIVE FLOATING cumpco POSITION ADVANCE UNCLAHPED-o- ENG-AGES I SHOE I RATIVE CLAMPED DRESS POSITION WORKP'ECE CLAMPED IN INOPERATIVE ENGAGES p IN BORE IN SHOE POS'T'ON WORKP'ECE CLAM ED EXTENDS I CLAMPED+ ENGAGES UNCLAMPED+ FROM IN SHOE IN INOPERATIVE WORKPIECE ENGAGES END OF BORE POSITION WHEEL STEPS 3+4 REPEATED UNTIL FINISH SIZE REACHED WHEEL CLAMPED+ STARTS TO IN 5H0: INOPERATIVE ENGAGES CLAMPED RE TRACT POSITION WORKPIECE UNCLAMPED REMOVED IN OPERATIVE FL RETRACTED FROM SHOE POSITION 0A ING INVENTOR.

Pe fe'r ll. Re usse'r GRINDING MACHINE Peter U. Reusser, Ridgelield, Conn., assignor to The Heald Machine Company, Worcester, Mass., ,a corporation of Delaware Y Application August 14, 1958, Serial No. 755,075

7 16 Claims. (Cl. 51-165) This invention relates to a grinding machine and more particularly to apparatus arranged accurately to grind an internal bore in a workpiece.

In the finished grinding of internal bores, it has been the practice in the past to remove the abrasive wheel from the bore while a gauge is inserted to determine whether the bore has reached a predetermined size or not. One difficulty experienced with the practice of removing the wheel from the work is that, as the wheel moves out of'the bore, a taper remains and when the wheel is inserted again, the wheel climbs up the narrow taper and United States PatentO and the manner of its organization may be better understood by referring to the following description taken in connection with the accompanying drawings forming a part thereof, in which:

Figure l is a schematic view of an internal grinding machine embodying the principles of the present invention,

Figure 2 is an enlarged detailed view of a portion of the apparatus,

Figure 3 is a sectional view of the apparatus taken on the line III-III of Figure 2, and

Figure 4 is a chart showing the condition of the various elements of the invention at selected times during the grinding cycle.

Referring first to Figure 1, wherein are best shown the general features of the invention, the grinding machine, indicated generally by the reference numeral 10,

builds up very high forces over the length of the taper,

thus crushing the wheel. In order to eliminate this, the force has to be kept low enough so that the ends of the wheel are not crushed. .The ideal way to take care of this problem is to use a long wheel which extends from both ends of the bore and to use oscillations which are i.

very short so that the ends of the wheel never enter the bore. However, in order to gauge size accurately it is necessary that a gauge reading be taken at the end of each oscillation of the wheel. None of the previously is shown being used in grinding an internal bore in a workpiece 11, which workpiece in this case is shown as being the inner race of a ball bearing. It will be noted that in Figure 1 several of the elements are repeated for ease in understanding the invention. An abrasive wheel 12 having a drive shaft 13 is shown within the bore of the workpiece 11. The grinding machine is constructed so that feeding motion of the wheel 12 toward the surface of the bore of the workpiece takes place in a vertical direction, as shown by the arrow.

The wheel 12 and the shaft 13 are driven by a wheelhead 14 mounted on a table 15. The workpiece 11 is mounted in a support 16 having shoes 17 and 18 which known gauging systems will permit this type of opera- 5 tion. These and other difiiculties experienced with the prior art devices have beenobviated in a novel manner by the-present invention.

It is, therefore, an outstanding object of the invention to provide a grinding machine having a gauging system which permits'the wheel to stay within the workpiece during the entire grinding cycle.

Another object of this invention is the provision of a gauging apparatus in which entrance of the gauge into the workpiece bore is not necessary.

A still further object of the present invention is the provision of a novel compensation for variation of outside diameters of successive workpieces.

It is a still further object of this invention to provide a grinding machine containing a gauging apparatus for use with bearing races or the like in which means is provided for compensating'for variations in the outside diameters of workpieces and for gauging the internal diameter of the workpiece during an internal. grinding operation without removing the wheel from the bore.

It is another object of the instant invention to provide apparatus for compensating for varying outside diameters of workpieces having internal bores to be ground on a shoe-type grinding machine.

Another object of the invention is a provision of means engage the workpiece 11 on its outer surface. In the present case, contact is made in the semicircular groove usually formed-.on the outside periphery of the inner races of ball bearings. One end of the workpiece 11 is held against a drive platen 19 (see Figure 3) which is driven and which is slightly eccentric with the axis of the workpiece so that the friction forces tend to force the workpiece down into the shoes 17 and 18 so that the workpiece does not jump out'of the machine. A conventional clamping means, not shown, is provided at the other end of the workpiece to hold it against the drive platen 19.

An O.D. compensation feeler 21 is slidably mounted in a fixed base 22'of the machine and is resiliently biased by a spring 23 into engagement with the outside surface of the workpiece 11 at a point opposite the shoe 17. An O.D. nozzle 24 is also mounted on the base 22 in alignment with the outer end of the feeler 21 to detect axial movement of the feeler. An O.D. reference feeler 25 is slidably mounted relative to the base 22 to engage the outside diameter of'the workpiece 11 in the vicinity of the shoe 18 and this feeler is also provided with a sizing nozzle 26 which is directed parallel to the feeler and toward the workpiece. An I.D. feeler 27 is slidably mounted in the base 22 to contact the 'wheel 12 on occasion. A spring 28 biases the feeler 25 toward the workpiece and a spring 29biases the feeler 27 toward the wheel 12. The ID. feeler 27 is provided with a laterally extending block 31 which extends in frontof the nozzle 26 defining therewith a sizing gap.

The feeler 21 is provided with a clamping and swing ing means 32 while the feeler 27 is provided with a clamp 33. a i

.A source of air under pressure,'not shown, is connected through a line 34 to one side of a pressure regulating valve 35, the other side' of which is connected through a line 36 to the nozzle 24 and also through a line 37 to the nozzle 26. The

lines

36 and 37 are also connected-to a' pressure bellows 38. whoseouter end is connected to an electrical switch 39. The switchlies in a power line leading from an electrical power source, not shownyto 2f coil 41 which, when.energized, terminates the feed mechanism, not shown, of the grinding machine. A feed j apaeroe mechanism of the type which may desirably be used in the present grinding machine is shown in the patent to Schmidt et al. No. 2,771,714, wherein the solenoid 96 is the equivalent of the coil 41 shown in the present invention.

other side of the valve 43 is connected by means of -a line 461 to the clamp 33 associated with the ID. feeler 27. The pressure air line 34 is also connected by means of a line 47 to one side of a plunger-type valve 48 having a plunger 49 which is biased by a spring -1 in such a manner that the valve is normally opened when the valve is in its normal position. The other side of the valve 48 is connected by means of a line 52 to the clamping and swinging means 32 associated with the OD. compensation feeler 21. The

valves

43 and 48 are located under the table 15 which carries the wheelhead 14 in such a manner that their plungers may be contacted by earns 53 and 54 formed on the underside of the table. The particular location, arrangement, and shape of the cams and plungers will be more completely described in connection with the operation of the apparatus.

Referring next to Figures 2 and 3, wherein are best shown the details of the control apparatus, it can be seen that the OD. compensation feeler 2 1 is slidably mounted in a block 55 which, in turn, is mounted for swinging movement by means of

reeds

56 and 57 which connect it to a portion of the base 22. The feeler is mounted in a bore 58 and in this same bore is mounted the nozzle 24 which has a long nose and is surrounded by the spring 23. A port 59 extends through the block 55 and has access to the nozzle 24 and an exit port 61 passes through the block 55 into the bore 58 to provide an exit for any air which passes out of the nozzle between the end of the nozzle and the end of the feeler 21. The clamping and swinging means 32 consist of a bore 61 formed in the block 55 and carrying therein two plungers 62 and 63. The line 52 carrying air under pressure enters the bore 58 outboard of the nozzle 24 and gains access to the space between the plungers 62 and 63 by means of passages 64 and 65 extending through the block 55. A stop 66 is fastened to the base 22 in line with the plunger 63 and closely adjacent thereto, while a stop 67 is attached to the support 16 some distanceabove the block 55. An en larged passage 68 is formed in the support member 16 to permit free swinging of the feeler 21.

A passage 69 is formed in the support 16 to permit the entrance of the feeler 25 and to permit its engagement with the outer surface of the workpiece 11. The lower end of the feeler 25 is fixed in a block 71 having formed therein the passages leading to the nozzle 26; the line 37 is suitably attached to the block and to these passages. The ID. feeler 27 is slidably mounted in a bore 72 formed in a portion of the base 22 and the spring 29 lies in the bore at the outer end of the feeler, thus providing a compressive force between the end of the feeler and a plug 73 threaded into the end of the bore 72. A suitable diamond dressing tool 74 is also mounted in the base 22 beside the LD. feeler 27, but this construction forms no direct part of the present invention' A suitable recess 75 is formed in the portion of the base 22 containing the feeler 27 properly to seat the spring 28 which presses against the block 71 and in turn presses the feeler 25 continually against the outside diameter of the workpiece 11. The axis of the feeler 27 is somewhat inclined to a line at right angles to the axis of the wheel 12 so that the feeler may more easily engage a small portion of the wheel as it emerges from the bore. A surface 76 of the block 31 is arranged soas to be parallel to the axis of the-wheel and to cooperate with the nozzle 26 to form the sizing gap. The clamp 33 consists of a bore 77 formed. in the portion of the base 22 which contains the toward the workpiece and toward the support 16.

feeler 27, and a plunger 78 situated in the bore. Access to the bore 77 is provided for the line 46 so that pressure air may be admitted thereto.

The cross-sectional area of the QD. nozzle 24 is selected to be one-half that of the sizing nozzle 26; the apparatus is arranged so that, when a workpiece '11 of exactly the proper CD. is used in the machine, the OD. gap and the sizing gap will be equal at the moment that the proper I.D. is reached in the grinding cycle. The

selection of these relationships will be explained more fully hereinafter.

The operation of the apparatus of the invention will now be readily understood in view of the above description. Referring to Figure 4, it can be seen that at the beginning of the grinding cycle the wheel 12 is in retracted position and is outside of the bore of the workpiece away from the support 16. The workpiece is inserted in the support 16 so that its outside diameter lies against the shoes 17 and 18. At that time the OD. compensation feeler 21 is in the position shown in Figure 2 and is free to slide in its bore 58 under the impetus-of the spring 23. At the sametime the OD. reference feeler 25 is free to move vertically and is pressed upwardly by the spring 23. At this time the ID. feeler 27 is clamped by the plunger 78. This is because the valve 43 is in the condition in which the plunger 44 is contacted by the cam 54 and is depressed, so that the valve is open and air passes from a line 42 to the line 46 into the bore 77. The feeler 27, therefore, is not free to move in its bore 72 under the impetus of the spring 29. At the second stage of the grinding cycle the wheel 12 advances axially It is, of course, being rotated at a high rate of speed by the wheelhead 14. In passing toward the workpiece the wheel passes over the diamond dressing tool 74 and is dressed. At this stage of the cycle the workpiece is firmly held against the shoes 17 and 18; because the platen 19 is rotating and because of the eccentric position of the platen, the workpiece is forced into positive contact with the shoes 17 and 13. The O.D. compensation feeler is, of course, unclamped and engages the outside diameter of the workpiece 11. In a similar manner, the OD. reference feeler engages the outside of the workpiece, but the ID. feeler 27 remains clamped as before. In the third stage of the dressing cycle, the wheel resides within the bore of the workpiece and, as is evident in Figure 3, the wheel is slightly longerthan the bore, so that during this portionof the cycle it extends from both ends of the workpiece. However, it extends only by a sufiicient amount to permit the reciprocating action which is usual with machines of this type. During this third portion of the grinding cycle, when the wheel is entirely within the bore, the OD. compensation feeler 21 becomes clamped and is moved into an inoperative position. This is be cause of the fact that the cam 53 no longer depresses the plunger 43 of the valve 48. While the wheelhead and wheel were in retracted position, the cam '53 held the plunger 49 in a downward position, so that the valve was in effect closed and the line 52 was connected with atmosphere so that clamping did not take place in the clamping means 32. As the wheel moves into the bore, however, the cam 53 .is removed from the plunger so that the plunger moves upwardly to connect the air pressure line 47 to the line 52 and to permit air to enter the bore 61 in the block 55. The air, therefore, presses the plunger 62 and 63 apart. This has the effect first of clamping the feeler 21 in its bore 58 and, secondly, to move the block and feeler upwardly about the pivot furnished by the

reeds

56 and 57. The block ultimately strikes the stop 67 and cannot move upwardly further. By that time the feeler 21 has been moved away from outer surface of the workpiece 11. The 0D. reference feeler 25 continues to engage the outside diameter ofthe workpiece and the ID. feelerv 27 is'stillclamped At the fourth part of the cycle the wheel at the end of one of its reciprocationsexenema reference feeler 25 continues to engage the workpiece. TheLD. feeler 27, however, is unclamped and engages the wheel. I This is because 'of the fact that, as the wheel comes out of the bore, the earns 53 and 54 straddle the plunger 44 of the valve 43 and the plunger is no longer depressed. This means thatthe plunger is in its upright position in which the line 42 is not connected to the line 46 and the line '46 is open to atmosphere. The plunger 78is thus relieved of pressure and the spring 29 presses the feeler 2 7 forwardly against the surface of the wheel 12. The sizing gap, which is the space between the nozzle 26and the surface 76 of the block 31 is, therefore, indicative of the wall thickness of theworkpiece at that moment. The condition of the elements described in connection with

Steps

3 and 4 are repeated as the wheel reciprocates within the bore of the workpiece. The ID. workpiece feeler 27 being clamped when the wheel does not extend from the bore and being unclamped and engaging the wheel when it does extend from the bore. Eventually the pressure isreached at which the bellows 38 closes the switch 39 and energizes the coil 41 thus stopping the feed of the machine and retracting the wheel. 'In Step 6 of the cycle, wherein the wheel starts 'to retract, theOlD. compensation feeler 21 is still clampedand is in its inoperative position. The-OD. referencefeeler 25 continues to engage the outside diameter of the workpiece and the LD. feeler 27 is in clamped condition. The finalStep -7 of the cycle comes about when the wheel is entirely retracted and the workpiece is removed from the shoe. With'the wheel in retracted position the cam 53 again engages the plunger 49 of the valve 48 and puts it in lower position so that theline 52 is:op en toatmosphere and the block 55 swings downwardly and the feeler 21 is free to slide in 'its'bore 58 under the impetus of the spring 23; The CD. reference feeler 25, as always, continues to float in raised position under the biasing action of the spring 28; furthermore, the LD. feeler 27 is clamped, since the cam 54 resides on the upper end of the plunger 44 of the valve 43 and causes airipress'ure to act against the plunger 78-.

As has been described above, the bellows 38 actuates the switch 39 to end the grinding cycle when the pressure in the bellows rises above a pre-determined value. The pressure inthebellows is determined by the sum of the leakages through the OD. gap and through the sizing gap. At the beginning of the grinding cycle the sizing gap is very large so that the pressure in the bellows is fairly low,'irrespective of how small the CD. is. As the workpiece bore approaches the desired size the sizing gap gets smaller and smaller. Eventually, the amount of air escapingfrom the OD. gap and from the sizing gap is so small thatthe pressure rises sufficientlyto cause the bellows 38 to ,close the switch 39 and terminate the grinding cycle. Let us suppose, for instance, that the outside diameter of vthe workpiece is larger than its normal value.- Then, the OD. 'gap is small'and the leakage of air through the OD, gap is also small so that its pressure contribution, to the bellows" 38 .is larger than normal; this meansthat the'sizing gap does nothave to become quite as small as usual to bring the total pressure up to the amount necessary to actuate the cycle stopping switch; Naturally, since the sizing gap is larger, when the switch is actuated inthis unusual condition, the wall thickness-(O.D.I'.D./2) will be greater, which is what is desired to give a fixed I.D. when the 0D. is too large. If the cross-sectional area A of the OD. nozzle is selected to be twice that of the: cross: sectional area B of the sizing nozzle 26, the change in sizing gap will exactly compensate for the fact that the OD. istoo large. 1 This is because ofthe fact that, if the. O.D. is large by a certain amount d, the wall thickness must be increasedby half that amountd/Z, to obtain the.

(normal O.D. gap).

selected I .D. f Since'the'O;D.1gap increases the same amount as the OD. decreases, thus increasing the escape- 'men t area by the nozzle circumference multiplied by the change in gap, the sizing gap (at the moment of switch actuation) must be decreased an amount sutficient to keep the total of the escapement areas constant. The amount of decrease of the sizing escapement area must be equal to the increase in e'scapement area at the OD. gap. That is to say, I want to keep the sum of the escapement areas the same, irrespective ofrwhether the 0D. is large or small. This means that 1e 3.14c (normal, sizing gap decrease in the sizing cap e) plus n r 3.14 (normal O.D. gap-i-d) should always be maintained equal to (normal sizing gap) Since it is necessary to keep the ID. constant, it is necessary that e equal d/2; then BXd/Z must equal A d or A/B equals /2. If the area, A, of the OD. nozzle is /2 of the area B of the sizing nozzle, the correct compensation of ID. will be made for every variation ofO.D. It will be understood that, since the nozzle 24 of the OD. gap memorizes the diameter of the-workpiece before the grinding cycle begins, the subsequent expansion of the workpiece during the grind ing cycle will not afiect the size of the finished surface after the workpiece has cooled. The apparatus, therefore, is effective to compensate for thermal changes during the grinding cycle.

While certain novel features of the invention have been shown and described and are pointed out in the annexed claims, it will be understood that various omissions, substitutions and changes in the forms and details of the device illustrated and in its-operation may be made by those skilled in the art without departing from the spirit of the invention; 1 l

The invention having been thus described what is claimed as new and desired to secure by Letters Patent is: 1'. A grinding machine for use with a workpiece: having an .outer surface and a bore of circular cross-section, comprising means giving a first signal indicative of the position of the said outer surface of the workpiece relative to a reference plane, means giving a second signal indicative of the position of the surface of. the bore of the workpiece relative to the reference plane, the said second signal changing during the grinding operation as the diameter' of 'the bore becomes larger, means adding the first and second signals and serving to terminate-the grinding operation when the sum reaches a predetermined value.

2. A grinding machine for use with a workpiece hav-' ing an outer surface and a bore of circular cross-section, comprising an abrasive wheel for grinding the surface of the bore, the wheel being longer than the bore so that it I extends from the ends of the bore, means adapted to engage the outer surface for producing a first signal indicative of its positionrelative to a reference plane, means for engaging the surface of the wheel when it extends a substantial amount from one end of the bore, the posidiameter 'of the bore becomes larger, means adding the fir'stand second signals in serving to terminate the grind ,ing operationwhen the sum reaches apredetermined value.

3, A grinding machine for-use with a workpiece ,having an'outer surface and a bore of'circular cross-section, comprising an abrasive wheel'for grinding thesurfaceof the bore, the wheel being longer than the bore so that it extends from the ends of the bore, means adapted to engage the outer surface for p roducing a first signal indicative of its position relative to a reference plane,.means for. engaging the surfaceofthe wheel when it extends a substantial amount from one end of thebore, thewposition of said means producing a second signal indicative of the position of the surface of the bore of the workpiece relative to the reference plane, means for maintaining the second signal at its preViousvaIue; while. the wheel is in the bore and is not engaged with said means the said second signal changing during the grinding operation as the diameter of the bore becomes larger, means adding the first and secondsignals and serving to terminate the grinding operation when the sum reaches a pre-determined value.

4. A grinding machine for use with a workpiece having an outer surface and a bore of circular cross-section, comprising an air gauging system ineludingasizing nozzle and a sizing surface associated therewith for determining the air escapement area, a-feeler engaging the outer surface and serving to move the sizing nozzle an amount in dicativeof the positionofthe said outer surface .of the workpiece relativeto a reference plane, a:feeler serving gto movethesizing surface an amount indicative of the position of the surface of the bore of the workpiece relative to the reference plane, the said second signal changing during-the grinding operation as the diameter of the bore becomes larger, the sizing nozzle andsizing plane determining an air pressure which serves to terminate the grinding operationwhen the pressure reaches a predetermined value. v

5. A grinding machine for use witha workpiece having an outer surface and a bore of circular cross-section, comprising an abrasive wheel for grinding the surface of the bore, the wheel being longer than the bore so that it extends from the ends of the bore, an air gauging system including a sizing nozzle and a sizing surface associated therewith for determining'theair escapement area, a feeler engaging the outer surface and serving-to. move the sizing nozzle an amount indicative of the positionaof the said outer surface of the workpiece relative to a reference plane, a feeler for gauging the surface of the; wheel when it extends a substantial amount from one end of the bore, the-feeler serving to move the sizing surface an amountindicative of the position of the surface of the bore of the workpiece relative to the reference plane, means for fixing the, position of the feeler while the wheel is in thebore' and is not, engaged with the feeler, the said sizing surface changing during the grinding operation as the diameter of the :bore becomes larger, the sizing nozzle and'sizing plane determining an air pressure which serves to terminaterthe grinding operation when the pressure reaches a pre-determined value.

6. A grinding machine for use with a workpiece having, an outer. surface and a bore of circular cross-section, comprising-means giving a first signal indicative ofthe diameter of the outer surface, a shoe having arsurface contacting the said outer surface and supporting the workpiece during a grinding operation,.means. giving. a second signal indicative of the position of the surface of the shoe relative to a reference plane, and means operative to terminate the grinding operation when the bore has been enlarged to a normal finished size varied by an amount which is proportional to the'amount. of variation of the ratio of the first signal to theisecondvsignalfrom a predetermined value..

7. A grinding machine for usetwitha workpiece;hav.- ing an.- outer surfaceand, abore: of circulargcross-section,

cpmprisingggrinding element, means-adaptedto engage theouter surface for producing a first signal indicative ofLthefdiame't'er or the outer surface, a shoe having a surface contacting the said outer surface and supporting the workpiece during a grinding operation, means adapted .to engage the grinding element for producing a second signalfindicative: of the position of the surface of the shoe relative to a reference plane, a given change in the diameter. ofthe. outer surface producing one half as much. change in the first signal as is produced in the second signal by the same amount. of change in the position of the-surface of the shoe relative to the reference plane, and means operative to terminate the grinding operation when the bore hasbeen enlarged to a normal finished size varied by an amount which is proportional to the amount of variation of the ratio of the first signal to the second signal from a pre-determined value.

' 8. A grinding machine for use with aworkpiece having an outer; surface and a bore of circular cross-section, comprising means adapted to engage the outer surface for producing a first signal indicativeof the diameter of the outer surface, said means being disengaged from the workpiece at the beginning of agrinding operation and maintaining the first signal at its previous value, a shoe having a-surface contacting-the said outer surface and supporting the workpiece during a grinding operation, means adapted to engagethe grinding element for producing a second signal indicative of'the position of the surface of the workpiece relativeto a reference plane, and means operative to terminate the grinding operation when the bore has been enlarged to a normal finished'size varied by an amount which'is proportional to the amount of variation' of the ratio of the first signal to the second signal frorn'apre-determined value.

9; A grinding machine for useiwith a workpiece having an outer surface and a bore ofcircular cross-section, comprising an air gauging system including an'outside diameter compensating nozzle and a sizing nozzle, the compensation nozzle being responsive to the position of a feeler engaging the workpiece for producing a first pressure indicative of the diameter of the outer surface, a shoe having'a surface contacting the said outer surface and sup? porting the workpiece during a grinding operation,'the sizing nozzle being responsive to the position of afeeler for. producing a second pressure indicative of the position of the surface of the shoe relative to a reference plane, a meansoperative to terminate the grinding operation when the bore has been enlarged to a normal finished size varied by an amount which is proportional to the amount of variation of the ratio of the first-pressure to .the second pressure from. a pre-determined value.

10." A grinding machine for usewith a workpiece having an-outer surface and a bore of circular cross-section, comprisingan airgauging system including an outside diameter compensating nozzle and a sizing nozzle, the areas of the said nozzlesbeing in the ratio ofone to two, the compensating nozzle being responsive to the position of an associated feeler for producing a first pressure indicative of the' diameter of the outer surface, means for moving the compensating nozzle feeler away from the workpiece at the beginning-of a grinding operation and maintaining the first pressure at its'previouslvalue, a shoe having a surface contacting the said outer surface and supporting the workpiece during a grinding operation, thesizing nozzle being responsive to the position of an associated feeler for producing a second pressure indicative of theposition of the surface of the shoe relative to a reference plane, a given change in the diameter of the outer surface producing one half as much change in the first pressure as is produced in the second pressure by the same amount of change in the position of the surface of the shoe relativeto the reference plane, and'meansoperative to terminate the grinding operation when the feed depth has reached: a IlOImfliIfiI'llSh..POSltlOIl. varied by an amount which. isJ/z. of thesQDuvariati'on: and: the resulting air pressurehas reached apre-determinedvalue;

11. A grinding machine for use with a workpiece having an outer surface and a bore of circular cross-sectional shape, comprising means giving a first signal indicative of the diameter of the outer surface, means giving a second signal indicative of the position of the surface of the bore relative to a fixed reference plane, the said second signal changing in value during the grinding operation as the diameter of the bore becomes larger, a shoe having a surface contacting the said outer surface and supporting the workpiece during a grinding operation, means giving a third signal indicative of the position of the surfaceof the shoe relative to the reference plane, and means for receiving and adding the three signals and terminating the grinding operation when the summation of the signals reaches a pre-determined value.

12. An internal grinding machine for use with a workpiece having a bore and an outer surface of circular crosssection comprising an abrading wheel, a support for contacting and supporting the outer surface of the workpiece during the grinding operation, the support including shoes contacting the outer surface at angularly spaced positions, an outside diameter compensation gauge engaging the outer surface of the workpiece at a position diametrically opposite the position of contact with one of the shoes and giving a first signal indicative of the diameter of the workpiece, an outside diameter reference gauge engaging the outer surface of the workpiece near the position of contact with one of the shoes, an inside diameter gauge engaging the wheel when it extends from the bore, the reference gauge and the inside diameter gauge being interrelated to give a second signal indicative of the wall thickness of the workpiece, the second signal changing as the grinding operation progresses, and means're'ceiving the signals and acting to terminate the grinding operation when their sum reaches a pre-determined value.

13. An internal grinding machine for use with a workpiece having a bore and an outer surface of circular crosssection, comprising an abrading wheel, a support for contacting and supporting the outer surface of the workpiece during a grinding operation, an air gauging system including an outside diameter compensating nozzle and a sizing nozzle, the areas of the said nozzles being in the ratio of one to two, the support including shoes contacting the outer surface at angularly-spaced positions, the outside diameter compensation nozzle having an associated feeler engaging the outer surface of the workpiece at a position diametrically opposite the position of contact with one of the shoes for producing a first pressure indicative of the diameter of the workpiece, an outside diameter reference gauge engaging the outer surface of the workpiece nearer the position of contact with one of the shoes, an inside diameter gauge engaging the wheel when it extends from the bore, the reference gauge and'the inside diameter gauge being interrelated with the sizing nozzle to give a second pressure indicative of the wall thickness of the workpiece, the second pressure changing as the grinding operation progresses, and means receiving the pressure and acting to terminate the grinding operation when their sum reaches a pre-determined value.

14. An internal grinding machine for use with a work piece having a bore and an outer surface of circular crosssection, comprising an abrading wheel, a support for contacting and supporting the outer surface of the workpiece during a grinding operation, the support including shoes contacting the outer surface at angularly-spaced positions, an outside diameter compensation gauge engaging the outer surface of the workpiece at a position diametrically opposite the position of contact with one of the shoes and giving a first signal indicative of the diameter of the workpiece, means for moving the compensation gauge away from the workpiece at the beginning of a grinding operation and maintaining the said first signal at is previous valve during the time that the compensation gauge is so moved, an outside diameter reference gauge engaging the outer surface of the workpiece near the position of 7 contact with one of the shoes, an inside diameter gauge engaging the wheel when it extends from the bore, the reference gauge and the inside diameter gauge being interrelated to give a second signal indicative of the wall thickness of the workpiece, the second signal changing as the grinding operation progresses, and means receiving the signals and acting to terminate the grinding operation when their sum reaches a predetermined value.

15. An internal grinding machine for use with a workpiece having a bore and an outer surface of circular crosssection, comprising an abrading wheel, a support for contacting and supporting the outer surface of the workpiece during a grinding operation, the support including shoes contacting the outer surface at angularly-spaced positions, an outside diameter compensation gauge engaging the outer surface of the workpiece at a position diametrically opposite the position of contact with one of the shoes and getting a first signal indicative of the diameter of the workpiece, an outside diameter reference gauge engaging the outer surface of the workpiece near the position of contact with one of the shoes, an inside diameter gauge engaging the wheel when it extends from the bore, a reference gauge and the inside diameter gauge being inter-related to give a second signal indicative of the wall thickness of the workpiece, the second signal changing as the grinding operation progresses, a given change in the diameter of the outer surface producing in the second signal by the same amount of change in the position of the surface of the shoe relative to the reference plane, and means receiving the signals and acting to terminate the grinding operation when their sum reaches a predetermined value.

16; An internal grinding machine for use with a workpiece having a bore and an outer surface of circular cross-section, comprising an abrading wheel for grinding the surface of the bore, the wheel being longer than the bore so that it extends from the ends of the bore, a support for contacting and supporting the outer surface of the workpiece during a grinding operation, an air gauging system including an outside diameter compensating nozzle and a sizing nozzle, the areas of the said nozzles being in the ratio of one to two, the support including shoes contacting the outer surface at angularlyspaced positions, the outside diameter compensation gauge nozzle being responsive to the position of an associated feeler engaging the outer surface of the workpiece diametrically opposite the position of'contact with one of the shoes for producing a first pressure indicative of the diameter of the workpiece, means for moving the compensation gauge away from the workpiece at the beginning of the grinding operation and maintaining the first pressure at its previous value, an outside diameter reference gauge engaging the outer surface of the workpiece near the position of contact with one of the shoes, an inside diameter gauge engaging the wheel when it extends a substantial amount from one end of the bore, means for maintaining the inside diameter gauge at its previous setting while the wheel is in the bore and is not associated therewith, the reference gauge and the inside diameter gauge being inter-related with the sizing nozzle to give a second pressure indicative of the wall thickness of the workpiece, the second pressure changing as the grinding operation progresses, a given change in the diameter of the outer surface producing one half as much change in the first pressure as is produced in the second pressure by the same amount of change in the position of the surface of the shoe relative to the reference plane, and means receiving the pressures and acting to terminate the grinding operation when their sum reaches a pre-determined value.

2,019,066 Balsiger Oct. 29, 1935 Schmidt et al. Nov. 27, 1956