US1429308A

US1429308A - Tool-grinding machine

Info

Publication number: US1429308A
Application number: US331213A
Authority: US
Inventors: Wachtler Franz Louis
Original assignee: Individual
Current assignee: Individual
Priority date: 1919-10-16
Filing date: 1919-10-16
Publication date: 1922-09-19
Anticipated expiration: 1939-09-19

Description

F. L. WACHTLER. TOOL GRINDING MACHINE.

APPLICATION FILED ocT; 16, 1919 1,429,808., Patentedsepm9,1922.

TSHEETS-SH E E F I.

F. L. WACHTLER.

TOOL GRINDING MACHINE.

APPLICATION FILED OCT-16, 1919.

1,429,308. v at n easept. 19, 922,

7 SHEETS-SHEET 2.

F. L. WACHTLER.

TOOL GRINDING MACHINE.

APPLICATION FHLED OCT. 16, 1919.

1,429,308, PatentedSept. 19, 1922.

7SHEETSSHEET 3.

F. L. WACHTLER.

TOOL GRINDING MACHINE.

APPLICATION FILED OCT. 16, 1919- 1,429,30 Pa tented Sept. 19, 1922;

7 SHEETS-SHEET 4.

F. L. wAcHTLg-iR TOOL GRINDING MACHINE.

APPLICATION FILE D OCT. 16. I919- Patented Sept- 19,1922.

7SHEETS-SHEET 5- I F. L. wAcHuE TOOL GRiNDlN-G MAQHINE.

APPLICATION FILED OCT. 16, 1919.

' l u ".127 sS HEETS-SHEET a.

l ,2 A f Y Ha:

Patented Sept. 19, 1922.

Patented Sept. 19, 1922. I

FRANZ LoUIs. WAGHTLER, -or anossnmram, GERMANY.

; TOOL-GRINDINGMACHINE- Application filed October 16, 1919. Serial No. 331,212,

To all whom it may concern: I Be it known -that I, FRAN LOUIS Wiiorrr- LER, a citizen of the Republic of Saxony, Germany, residing at 'Grossenhain, Germany, have invented certain new and useful Improvements in Tool-Grinding Machines (for which I have filed applications in Germany, G. 46,302 XII/67 dated 21st of Feb-- ruary, 1918; Germany, G. 46,536 XII/67 dated 13th of April, 1918; Germany, G,

are disposed on a reciprocating slide, so that Y the tool is passed before a stationarily journaled revolving grindingpdisc, still show+ even if working automaticallymany drawbacks, whichresult in the teeth to be ground being attacked veryunevenly by the grinding disc; SQ that'the height'of the ground teeth variesand'the latter do not attack the work evenly; the consequence is that the projecting teeth easily break off, and

the toolatoleast is'soon blunted and becomes useless. Under an inaccurately regulated pressure the cutting'edges of the tools are frequently also heated so that they become soft and unserviceable because the'reciprocated tool can be ground only while the tooth is passing the grinding-wheel in one direction, as the dead point in the feed gear renders it impossible to press the toolagainst the grinding wheel while the tooth is passing the latter in the opposite direction.' Therefore automatic tool grinding machine work uneconomically,.even if the return of the tool isaccelerate'd.

All these drawbacks are obviated by the new tool grinding machine according to the present invention; besides further advan-.

tages are-derived, which shall hereinafter be disclosed by the description of the construction'jof the'machine itself.

A feature of the machineaccording to the I present invention consists thereinthat the spindle of the center pointsupporting the one endof the mandril is *iournaled so as to revolve freely, whllst it is held in a certain position (grindingv position) by-means action frictionally' on it, whichmeans are adapted to cause, by a corresponding control, a revolution of said spindle in the one direction; the said means, furthermore, will admit of a revolution of the spindle in the opposite direction when a force, greater than the grinding pressure acts on the spindle, so that the mandril will on the one hand be held during its reciprocation in its grinding position by means frictionally acting on the center pointspindle, and may, furthermore, be turned by the same during the operation when tools with helical teeth are being ground, whilst on the other hand the turning of the tool with reference to the pitch of its teeth may be performed "durv ing the grinding operation and withoutsaid frictional means being disengaged, as soon as-the tool has moved out ofithe range of the grinding wheel. v

It is further necessary that the gear parts which produce said turning of the tool engage only at the very moment necessary for the reversing, and are immediately after again disengaged, so as to allow the mandril to revolve freely, independent of all, gear parts employed for saidturning. As everywhere in mechanical"construction the'most simple design will also here lead to securing a perfect working of the turning gear; therefore the known.,device of a ratchet wheel and pawls has been-employed, said ratchet wheel having a number'of notches for the engagement of 'the pawls, said notchescorresponding in number with the number of teeth on the tool' to be ground, so'that by simply exchanging the ratchet wheel the turning or dividing gear as we may call it,

may be readily adapted for tools of-any number of teeth, The intentionito secure the 'most simple design has furthermore lead to securing the said ratchet wheel immediately "on the mandril. This necessitated that the engagement of the pawl with the ratchet wheel cease immediately after the desired turn has taken. place. According to the present invention this is obtained by the pawl being carried by a spur wheel freely revoluble on the mandril. This spur wheel meshes with a Wheel on a haft pap frictionally journalled in the mandril headstock. 1 When revolved in one sense the said extension abuts against the one side of said recess, and thereby the pawl is brought into engagement with the ratchet wheel. When; revolved in the opposite sense the said pawl extension will abut against the other side ofthe recess and thereby the pawl is lifted fromf the ratchet wheel. By such. simple means itis possible to holdthe pawl in engagement with the ratchet wheel fitted d1- rectlyvon the mandril duringthe' time only,- which it is necessary for the respective turning, whilst during the other time,that is during the operative stroke, the mandril can revolve fully freely. -By the ratchet wheel being fitted directly on the mandril, all troubles by intermediate gears are obviated, which, as experience has proved,cause an inaccurate adjusting or setting of the tool.

Oncethus provision has been made that the setting of the tool relatively to the grinding disc'may. be performed independently of the dividing gear, also provision must be made for a proper operation of the machine, and also that the grinding wheel itself is reliably-held in its position during the whole operation. In grinding machines, however, in which the. shaft carrying the grinding tool or wheel runs at a high speed, it has i been found that the said shaft readily heats considerably in its bearings. This leads to an elongation of the shaft, which 'will thereafter axiallyvibrate. This again will have the result that the position'of the grinding wheel varies, so that the tool is submitted to an inaccurate grinding, more being ground of at some parts, less at others. This evil cannot be obviated by readjusting the heated shaft, because such readjusted shaft would seize on cooling down subsequently.

It is the object of the present invention to obviate also such drawbacks by arranging the shaft in such a manner that it is possible to compensate the change in the ,lengthof the shaft carrying the grinding wheel in such a manner that the said grinding wheel will always remain inexactly'the same place and the shaft does not vibrate axially in its bearings.

In the accompanying drawingsFigures 1 and 2 show the grinding machine in elevation, Fig. lbeing a side elevation and Fig. 2 an end elevation, seen-in the direction of the arrow in Fig. 1. Fig. 3 is a vertical longitudinal section through the 'mandril with the respective driving gear. Fig. 4 is an end elevationseen in the direction of the arrow in Fig. 3. Fig. 5 is an approximately mandril 12 carrying the tool 11.

horizontal section on the line 55 in Fig. 4.

tions thereof, in the one the chain wound around the spindle or its sleeve, respectively, having been omitted; Fig. 9 is an elevation of the mandril head stock seen from the rear; Fig. 10 is a detail side elevation partly in section of the mandril head stock; Figs. 11 and 12 show the dog and the grinding wheel. Figs. 1317 refer to a modified construction of the brake device; Fig. 18 being again an elevation of the mandril headstock, Fig. 14: a vertical central section therethrough, and Figp15 an elevation of the mandril headstock seen from the rear; Fig. 16 is a special modification of the means of securing the chain; Fig. 17 is a top view of the chain stretched out. Fig. 18 is a longitudinal section showing the journalling shaft in two different positions, both seen from above.

From the driving shaft 1 (Figs. 1 and 2) the shaft 2, axially shiftable in its lower bearing, is driven by--means of worm and worm wheel; the upper end of this shaft 2 is journalled in an overhang bearing of the body part 4, which may be raised and lowered by means of handwheel 5 and screw spindle 6. At the upper end of the vertical shaft is disposed a cr'ankwith connecting rod 7, which acts on a slide 9 guided on the slide table .8yand reciprocates the said slide. On said slide is fitted the headstock 10 and the mandril headstock 12. Between the center'point of the mandril headstock and the center point of the headstock 10 is fitted the By such means the tool is carried past the revolving grinding wheel 13, the shaft of which is supported in the forked bearing 14:, when the slide 9 is reciprocated.

Close to the upper end of the vertical shaft 2 is fitted a cam-disc, on the surface of which is disposed aroller 15, carried by lever 16 ,keyed to a horizontal shaft 17. In consequence thereof this horizontal shaft will be oscillated by the lever 16 as the roller overrides the projection on the cam disk at each revolution of the vertical shaft 2 viz, each time after the reciprocation of slide 9 on table 8 has been completed. This oscillation of shaft 17 is transmitted by rod gear to a horizontal shaft 19 disposed parallel to the mandril spindle 18 (see also Fig. 5). From 'shaft.19 the oscillation is transmitted, by

described by what means hereby the oscillation will during such transmission act in one sense only on the said man-dril splndle. By such means after each operative stroke, 1. e.,

after each complete reciprocation of the-tool,

rec

the latter is advanced by one tooth, so that.

' a fresh tooth will come into contact with the grinding wheel.

' Themandril spindle 18 (Figs. 3 and 5) which isrigidly secured thereto by means of a nut'24 and a washer 25. The spindle runs in two ball bearings, disposed in theparts' 26 and 27 of the forked headstock 12. The

ball races 28-on the spindle 18 are held by means of an intermediate sleeve 29 and nuts 30'and '31. The ball races 32 in the;

bearings

26 and 27 are secured by means of a 'nut 33. On-an extension of theboss of part'26 is fitted freely revoluble a spur gear 21, on which -a ring 34 is screwed. This ring 34 has. a pin 35 on which is fitted a' pawl 36, which-cooperates .with the'ratchet wheel 23 in a mannerto be hereinafter described. 0n the inner side of'the extensiorf-of boss 26 an annular body is'frictionally coupled thereto by means of a slip spring 37, said annular .body having an upwardly extending horn 38 (Fig. 4). This horn has at its upper end a recess 39, in which engages a nose on the boss of pawl 36.

The gear 21 carrying the pawl meshes, as beforesaid, with the gear '20- onshaft 19. This shaft '19, which is parallel to the manedril spindle is oscillated in the. following manner: From the vertical shaft 2 the horizontal shaft 17 ,to which lever 16 is fitted, is oscillated once at each' operative stroke by -means ofithe cam disc and the lever 16 engaging with roller 15 in the groove of said cam disc. To the one end of shaft 16 is fitted a lever 41,'having in its free end a curved guide slot. In this guide slot a block fitted to the end of a rod 42 may be adjusted. The said rod 42 acts on a lever 43 which is fitted freely revoluble on shaft 19 (Fig. 5). On"

gear train has been employed in order to. allow ofreadjusting the tool relatively to' the grinding wheel. Such readjustment may be necessary in consequence of the wear of the grinding wheel and the tool in course of time. For this purpose the pin 46, carrying the

gears

45 and 47, is fitted to a worm wheel 49, the worm 50 of which may be turned by means of a hand wheel 51. The turning of the worm wheel will cause the

gears

45 and 47 to roll on the

respective gears

44 and 48 and to thuscause a lead or lagging of the shaft 19, which means a fine adjustment of the total relatively to the.

grinding wheel. The gear 20 fitted to shaft performed in the following manner:

19 is axially adjustable withits bearing car'- ried by slide 9, for which purpose a key 52 to of suitable length has been employe hold gear 20 to shaft19.

The mandril 12 with the tool 11 is held inoperative position in the following manner: On the sleeve 29 fitted to the mandril spindle 18 is wound a chain (Fig. 8).:. The one. end'of this chain is run over a roller 53 and carries a weight 54. The

otherend of the chain is coupled toa slide 55. This slide'tr'avels' in guides 56 crosswise to the axis of the mandril spindle, the said guides being fitted to the headstock 111. 111 v the middle of the guides 56 is disposed a pin 57, on which a pawl 58 is pivoted. This awl can be thrown over so that it engages in a recess '59 in slide 55 (see dotted lines in Fig. 8). When the said pawl thus engages in the recess in slide 55, the latter will be held in'a givehyposition, the pull of the weight 54 on. the chain forcing the slide against the pawl. weight; the chain wound around sleeve 29 has a high friction on the latter, the mandril spindle, which is freely revoluble in its

hearings

26 and 27 is held in its position determlned by the position of the slide. The friction of the chain is so great, that it exceedsthe grinding pressure. It is only necessary to provide that this position of the sleeve 29, and thereforealso on the mandrilfspindle 18 corresponds to the operative position, i. e., that position in which the tool bears with the face of-one of its teeth against the grinding wheel 13. The fine adjustment is Asr now, owing to the performed by aid of handwheel 51 in the manner hereinbefore described.

When, now, a fresh tooth .of the tool is to be' brought into contact with the grinding wheel, the tool will have to be advanced, and this will have to be at the moment when'the tool has been moved out of the range of the grinding wheel, i. e., after it, during its reciprocating stroke, has been passed twice along the grinding wheel. This advance is The gear 21 carrying the pawl 36 meshes in the manner hereinbefore described with gear 20 on shaft 19. Shaft l9.is oscillated, therefore also gear 21, carrying pin 35 of the pawl. Therefore also the extension 40 is. oscillated. If now the oscillation proceeds in the direction of the arrow in Fig. 4, the extension will bear against the left side of the recess 39. Thereby the pawl 36 is pressed into the ratchet wheel 23. notch therein and thus produces the movement necessary forturning the mandril recess 39 and thereby the pawl is lifted out from theratchet wheel. At a further turn in this direction the shoulder 60 of extension It engages in .the next.

40 finally bears against the'upper end of the part 38 having the rece'ss'39, so that said part 38 is. dogged against the action of its to the twist of the teeth of the tool.

cal'twist of theteeth. This twist may be" performed by ,the .parts producingthe ad- Vance without aifecting the mandril spindle, because'the pawl is lifted out immediately after the advance has been-completed. The arrangement which produces the twist of the mandril spindle in correspondence with the .helic'altwist of the tool must be so construct- .ed that it allows of the spindle being twisted during the advance. 4 The mandril spindle is twisted in correspondence'with the helical twist of the tool teeth is performed by aid of the hereinbefore described slide 55. This slide-has at its lower end a roller 61, with.

which it engages; on a guide-bar 62,- when the pawl 58 is lifted. This guide bar swivels on a central pin 63 and may be fixed in any adjusted position. The guide bar is stationary' and therefore does not participate in the reciprocating movement of slide 9 on table 8. On the other hand the slide 55 gliding crosswise to the axis ofthemandril spindle is dogged together with its guides 56 during the reciprocating movement of the tool. In follows therefrom that the slide will during such reciprocating be lifted and. lowered by the slantingly disposed guide bar 62. The adjustment of the guide bar must correspond slide 55 is held with its roller 61 down on the guide bar 62 by means of the weighted chain. The pull of this weight has the effect that thechain'wound on-thesleeve 29 exerts a pull on the slide 55, on the one hand, and

' on the other that on the slide 55 being raised and lowered, 'by the friction of the said chain'the sleeve 29, and with it the mandril spindle 18 is dogged.

According to the present. invention the chain is constructed in sucha manner that its upper part. acting on the slide 55 is composed of two parallel thrums 64, whilst the lower, weighted part consists of one thrum 65 ,only,,in such a mannerthat the part 65 remains in the gap between the two thrum's 64, where the chain is wound. on the sleeve 29.; Thereby it is possible that the middle I line of the chain always remains in the same plane'althou h the chain is wound on the sleeve 29. hen now a force appears which tends to turn the sleeve in the direct-ion of the pull of we1ght'54, viz., contrary to the arrow shown in Fig. 8 within the sleeve 29,

thefricti'on ofthe chain on sleeve 29 will oppose such force. Such force is the grinding 65 pressure exerted by the grinding wheel on The- eaeoa the tool. When, on the other hand, a force appearsywhich tends to turn the sleeve 29 and the man'drilvspindle 18 in. opposite direction--viz., in the direction of the arrow shown in Fig. 8 inside of the sleeve 29-such turning may proceed without any'difiiculty, as the weight acts towards slackening the 'ehain. Such turning will proceed when the advance is being" made, as in this case the mandril spindle 18 is by the ratchet gear '23, 36 dogged in the direction of the arrow (Figs. 4 and 8). The advance will therefore notaifect the weightin parts, which produceflthe twisting of the mandril spindle 18 taining this rough adjustment the dog,

which couples the mandril with the mandril spindle, is-made of a special form. This dog consists of a part 66'screwed to the end of the mandril. On a screw bolt 67 (see Fig. 11) are fitted two jaws 68, one to the right and one to the-leftof the part 66 screwed to the mandril. These jaws form a fork. They engage in a circular groove 69 in the nut 31on spindle 18 and are of a corresponding curvature. When, now, one of the nuts 70.0n the endof bolt 67 is tightened, the jaws68 are clamped both to the dog 66 and into'the annular groove 69. By such means the mandril 12 is dogged. As soon as one of the nuts is loosened, the clamping pressure ceases which holds the jaws 68 in the annular groove 69. Then the dog Ina be turned at will with the mandril l2. This'possibility of turning the mandril is employed for rough adjusting the tool. If one of the nuts 70 is loosened, and the center point is withdrawn into the headstock 10 by turning handwheel 71., the mandril 12 may be taken with the tool from'the machine. I

In Fig. 12 the grinding wheel 13 is shown in contact with the tool 11. One may see hew the tooth being ground bears with its face against the grinding surface. The ar-' row indicates the direction opposite to that in which the mandril must be. advanced for the nexttooth to be brought into contact.

accurate adjustment, which exactly corre- .sponds to the pitch. of the respective teeth of the tool. F or this purpose an arrangement is provided,-which may be termed the micrometer adjusting attachment. 9

The guide bar 62 islcoupled by means oi .inbeforedescribfed will not or not very well a bolt 71 (Fig. 10) with asector72 pivoted on a pin. 63' This sector forms a part of a worm wheel and meshes with a worm 73.

The worm, to which 'a handwheel 74 is at tached, is fitted freely revoluble on the one.

leg ofan angle bolt '75 .(shown separately below Fig. 6). Theother end of the angle bolt engages in an arm 77 extending from the bearing 76 of bar 62. On a collar 78 on-bol't 7 5 is a mark (a cut) and on the collar 79 of the .worm is a graduation from 0 9, To the end of'bolt 75 is attached a pointer 80, the point of which plays over a dial on sector 7 2: The zero of this dial coincides with the point of said pointer, when the guide barv 62 is absolutely horizontal,

thus in an indiflerentposition, and therewillbe' no twist of the mandril. The dial is so divided that at each full revolution of the worm the sector will be moved by one graduation relatively to the pointer. The graduation-on the collar of the worm allows the operator/to set the attachment to 1/10 of a divisionof the dial on the sector. The guide bar 62 can be fixed in-any adjusted position by means of nut 81 on bolt 63..

The mark on bolt 75 may also be omitted and the reading may be made along. the

pointer.

I The tool bears in the manner shown in Fig. 12 with the face of one of its'teeth against the grinding wheel l3.

According to the present invention a chain weighted or under action of a spring is wound around the mandril spindle which is journalled freely revoluble in its bearings; the upper end of'said spring being at- 'tached to a slide which may travel crosswise to the axis of said spindle'and be fixed. I

The pull of the weight or spring has the effeet that the spindle is held by friction with the chain in its operative (or grinding) position, providing that the grinding pressure. of the spindle acts in the direction of the pull of'the weight or spring. If, however,

the spindle is turned opp'ositelyto the pull of said weight orspring, this may be per-.

formed without any nominallresistance, so that such turning'may be utilizedfor the advance of the toolorthe accurate ad ustthe end of the chain is .attached,-is moved,

' main.

the spindle will be turned,'the hereinbefore described :c onditions regarding the resistance against't-he turning of the spindle in by means ofthe slide is utilized, when tools siderable pressure, the arrangementshereperience that the chain'be wound several in such a manner that the links are set off mentof. the same. When the slide, to which The rotation of the spindle producedwith helical teeth are to be ground, with When toolshave to beground ata contofore disclosed, and including" those here- 7 hereinbefore described arrangement by ina creasing the pull ofthe weight ,or the spring. By thus increasing the brake effect, however, also the advance of the tool will become more difiicult, so that it is either necessary tomake provisions, to annul the brake effect during the. advance, or to heavily weighten the advancing'gear, for it to overcome the frictional resistance.- In either instance. the grindingwill suffer thereby, by springeffects being introduced into the gearing, which will impair the production of straight ground surfaces. f

Whereas in the'hereinbefore described arrangement the chain is .wound once only .around the spindle, the present invention provides for such purpose according to extimes around the spindle. -It is thereby secured that the spindle cannot by any means he turned in the direction of the pull of the chain, because the'frictional resistance is too extraordinarily great, that it will resist even the highest grinding pressure; ..but the spindle may without any essential resistance be turned inthe opposite direction the same as before. It is thereby obtained that on the one hand the brake effect on the spindle will meet very high grinding pressures,

whilst on the. other hand, the; possibility of readily turning the spindle for advancing the tool is not reduced.

It is, insuch case, important, that'the individual turns'of the chain do not touch each other, because, as soon as the spindle is v turned from the slide, to which the. end of the chain is secured, the chain will no more be stationary but be partially wound or unwound, respectively, whereby the thrums, if 4 they rub against each other, would not only i'inpare' the effect but also be destroyed by wear. For preventing this the 'part of the chain which is to wind on the spindle is made 2 meas es glides between the guides 81 connected by set-screws, which may be set at will from the handwheel 74 by means of a worm gear, so

that when theheadstock 111 is shifted longi tudinally,-the slide 55 is moved transversely,

when the guides 81 are set at an angle (con trary to the position shown in .F i 13).

To the upper end of the slide 55 is attached the chain 64. This chain is wound in several (3) turns around the spindle or a sleeve 29 connected to the spindle, said sleeve being freely revoluble in the

bearings

26, 27 of the headstock. The other end of the chain is attached to a spring bolt 82, which is fitted axially displaceable to the lower end of the slide 83 and is pulled downward. by 'th spring 8 1 around it.

The spring 84 need be only quite weak, be-

cause the three turns of the chain on the spindle will already afford so great a frictional resistance against the turning of-the spindle in the one direction, that no con.- siderable pull by weight or spring on .the

. end of the chain is anymore required. The

object is only to yieldingly secure the end of the chain, so as to keep the chain in order in its position.

As may be seen in particular from Fig. 17, the chain is so constructed, that its two ends .64 and 64 extend in a straight-direction.

The part of the chain, however, which winds on the sleeve 29 has its links set off to one side, so that the individual turns of the chain on the sleeve 29 willnot touch each other (Fig. 15). When the spindle isthere- 'fore turned, by the travel of the slide 55,- the chain, winding onto or unwinding from the spindle, cannot rub with its turns against each other.

3 In the form shown in Fig. 16 the slide 55 is provided with a rack in which engages a gear 86 loosely revoluble on'sleevc 29. To-

grinding wheel 13 to be secured by means of the screw thread 87.

The invention wliich. is intended to be chiefly employed with precision machine tools with high-speed spindle in thrust bearings, provides that the'shaft revolves with.

two conical collars tapering towards each other, 88, 89 in two correspondingly bored journals 90, 91. This type of bearing is employed forreason'of the greater possibility of accurately adjusting the same.

Ifnow, as it is the case in the left hand bearing with regard to

cones

92, 93 and with the right hand bearing with regard to the

cones

88, 89 the two cones of the bearing are .fixed relatively to'the shaft .(on the left sleeve 941) an axial play will appear in the bearing on the latter being much heated, so that the spindle will greatly vibrate and the accuracy of the work will suffer. In the bearing shown-this trouble will be particularly noticed in the right hand bearing, be

cause the-latter is under the greater load, the

bearmg.

I may here point out that even 1f an even heating of the two

cones

88, 89, on the one one hand, and of the sleeve'90 on the other be supposed, the sleeve must expand radially more when the sleeve is madein the usual and approved manner of gun metal, because the cones are made of steel or iron, when thus the metal of the sleeve has a higher coeificient of-expansion. The greater expansion causes the fit to slacken the more,

because it produces a radial'receding of the conical. line of the sleeve 90 from the angle formed by the cones, thus a relative shortening of the sleeve, which cannot be compensated by the greater longitudinal extension of the sleeve as a consequence ofthe higher coefficient of expansion.

-F or the purpose of maintaining the original fit even when the bearings heat,

thetwo

cones

88, 89 will,thereforehave to be approached towards each other in approximate correspondence withthe increasing heat or the expansion,respectively. According to the present invention the heat produced by the slipping of the belt is utilized in such a manner, that one of the cones, viz. 88, is formed by a sleeve 99 made in the form of a belt pulley 98. By said sleeve 99, which drives the spindle 96 by means of a key 100, bearing against the abutment formed by the lock nutslOl, 102,

it will, on being heated by the slip of the belt, force. the cone 89 to theright towards the cone 88 rigidly fitted to the spindle 96. As a heat producing agent not only the slip of the belt (which just at high speeds and small pulleys is unavoidably great.) but also the lateral shifting of the belt (which likewiseappearsunder the said conditions with a high number of oscillations). Besides the same as the heating of the bearing, also the heating of the sleeve 99 by the slip of the belt will increase with the duration of the work and with the load, so that the utilization of the slip of the belt as source of Heat for producing the expansion of a slackening of thefit of the bearing caused by the heating of the latter.

The

locknuts

101, 102 allow, as anad-' justable abutment the regulation of the fit of the bearing.

. For adapting-the grinding wheel to the twists of tools with helical teeth, the'bearing 14 of the grinding wheel shaft is, as

groove is curved to 'a circular line 107 the center of which is situated at w (see also arrow in FigI-QO), viz., inthe vertical middle line of the grinding 'wheel 13. By shifting the sliding bearing the grinding wheel 13 may be brought into any angular position, one of which is shown in Fig. 20.

The intermediary position of the grinding wheel 13 shown in Fig. 19 is employed for tools with straight teeth.

With the new girinding machine both, tools-with pointed and with undercut teeth may beground, it being immaterial whether their teeth are parallel to the axis of the tool or helically wound to the right or the left, grinding wheels of any kind being used. I claim: 1. In a tool grinding machine in which i the tool .is fitted on a mandril held between two center points fitted to a reciprocating bination of a freely revolubly journalled spindle carrying the one of said center points, a flexible element wound around said spindle, a tensioning element connected to one end of said flexible element,theother end of said flexible element attached toa controlling member shiftable crosswise to the axis of the said spindle; k

2. In a tool grinding machine in which the tool is fitted on a mandril held between two center points fitted to a reciprocating slide, which movesthe tool past a stationarily revolving grinding wheel, the combination of a freely revolubly journalled spindle carrying the one of said'center points, a flexible element wound'around said spindle, a tensioning device connected to one end of the flexible element, the other end of said flexible element attached to a slide shiftable crosswise to the axis of the spindle, apawl engaging in and arresting .rides on said adjustable guide rail,

said slide, an adjustable guide rail, anda roller on said slide, with which said slide when not arrested by said pawl.

3. In a tool grinding machine in which the tool is fitted on a mandril held between the two center points fitted to. a reciprocating slide, which moves" the tool past a stationarilyjrevolving grinding wheel, the combination of a freely revolubly journalled spindle carrying the one of said center points, a flexible element loosely Wound around said spindle, a tensioning device connected to one end of said flexible element,

the other end of flexible element attached to a slide shiftable crosswise to the axis of the spindle, a pawl engaging in and arresting said slide, a guide rail adjustable on a pin and a roller on said slide, with which said slide rides on said adjustable swivelling rail, when not arrested by said pawl, said chain holding said slide down against said guide rail, said guide rail fitted with a 'wormwheel sector, engaging with a worm rily revolving grinding wheel, the combination of a freely revolubly journalled spindle carrying the one of said center points, a

flexible element consisting by one half of two parallel thrums, in the other half of one central thrum adapted to'engage in the gap between the other two thrums, said chain wound with its two-thrum part loosely around said spindle, the one-thrum end of said chain carrying a flexible element, the other two-thrum end attached to a slide shiftable crosswise to the axis of the spindle a pawl engaging in and arresting said slide, a guide rail swivellingly adjustable on a pin and a roller on said slide, with which said slide rides on saidadjustable swivelling guide rail, when not arrested by said pawl,

said chain holding said slide down against said guide rail, said guide rail fitted with a worm-wheel sector, engaging with a worm havinga handwheel, andapointer and dial for reading the relative adjustment of said worm and sector. Y

5. In a tool grinding machine in which the tool is fitted on a mandrel held between two center points fitted to a reciprocating slide, which moves the tool past a stationarily revolving grinding wheel, the con'lfbination of a freely revolubly journalled spindle carrying the one of said centerpoints, a

flexible element, wound around the said spindle, the one end of said elementcarrying a tensioning device, the other end of said element attached to a controlling member shiftable crosswise to the axis of the said spindle,

a ratchet wheel having the same number of teeth as the .tool to be ground fitted on the spindle holding the mandrel, a pawl engaging in said ratchet wheel and carried by a member, revoluble on the mandrel spindle, means for oscillating said member on the 1 tool is fitted on a mandril held between two:

eaaeoe completion. of the reciprocating operative 9. In a tool grinding machine in which 65 stroke of the mandril, on said pawl an extension, a controlling member held by fric tion in the mandril spindle bearing and having arecess, in which said pawl extension engages.

6. In' a tool grinding machine in which the center-points fitted to a reciprocating slide, which moves'the tool past a stationarily revolving grinding wheel, the combination of a freely revolubly journalled spindle carrying the one of saidcenterpoints, means ac-ting on said spindle and adapted to turn said spindle in one direction, to hold said spindle in a given position (grinding position) and to allow of the said spindlebeing turned 1n the'opp'osite direction on a force exceeding the spin le, a slide carrying the grinding wheel, said slide having a web or the like, in the slide table a groove of a circular curve, the center of said circular curve beingin the vertical middle line of the grinding wheel, said web engaging in said groove.

.7. In a tool grinding machine in which the tool is fitted on a mandril held between two center points fitted to a reciprocating slide,-

which moves the tool past a stationarily revolving grinding wheel the combination of a freely revolubly journalled spindle carrying the one of said center points, means acting onsaid spindle, adapted to. turn said spindle in one direction, to'hold the said spindle in a given position (grin'dingposition) and. to allow of the said spindle being turned in the opposite direction on a force exceeding. the grinding pressure acting on the said spindle, the grinding wheel spindle having a double conical bearing, the one of the cones formed by asleeve non-revolubly fitted to. the spindle, and bearing against an abutment on said spindle, said sleeve so formed as to simulta neously serve as belt pulley. f

8. In a tool grindingmachine in which the.

the said spindle, the grinding wheel spindle having a double-conical bearing, the one of the cones formed by a sleeve non-revolubly fitted to the spindle, and bearing against an abutment on said spindle, consisting of two rindin'g pressure acting on the said the tool is fitted on a mandril held between two center points fitte'd to a reciprocating slide, which moves the tool past a station-- arily revolving grinding wheel, the combination of a freely 'revolubly journalled spindle carrying the" one of said center points, a chain wound several turns, around said spindle, in-the part of the said chain -which is thus wound around said spindle the links continuously set off on one side, the one end of said chain carrying a tensioning device, the .other end of said chain attached .to a cont'rollin crosswise to the axis o the said spindle.

10. In a tool grinding machine in {which the tool is fitted on a mandrel held between two center points fitted to a reciprocating slide, which moves the'tool past a stationarily revolving grinding wheel, the combination of a freely revolubly journalledspinmember shiftable dle carrying the one of said center points,

a chain wound several turns around said spindle, in the part of the .said chain which is thus wound around said spindle the links continuously set off on one side, theone end of said chain.carrying a .tensioning device, the other end of said chain attached to a slide shiftable crosswise to the axis of the spindle, a block on said slide, two guides adapted to be obliquely adjusted, said block on said slide, sliding between said adjustable guides.

11. Ina tool grinding machine, a cutter shaft adapted to carry a cutter, a tool supporting spindle adapted to carry a tool, means for intermittently advancing said spindle in strokes of predetermined length, .and adjusting means for causing the lead and lag ofsaidstrokes dependent upon the relative wear and adjustment of said cutter and tool for maintaining desired pressure between the same.

12. In a tool grinding machine,"a cutter shaft adapted to carry a cutter, a tool supporting spindle adapted to carry a tool, a reciprocating -member for advancing said spindle instrokes of predetermined length, and variable adjusting means arranged between the reciprocating member and the spindle for causing the lead and lag of said tool and cutter.

13. In a tool grinding machine, a cutter shaft adapted to carry a cutter, a tool supporting spindle adapted to carry a tool, a reciprocating member for advancing the spindle'in strokes of predetermined length, a differential mechanism connected between said reciprocating member and said spindle, and means for a justably anchoring an element of said differential mechanism for causing advance-of said spindle, said m ans -,when adjusted being adapted to vary the lead and lag of said stroke through said dif- 1,429,308 I, v Q

advancement of said spindle through said. differential mechanism upon operation of said reciprocating member, said manually adjustable device bein adapted to vary the lead and lag of s'aic strokes whereby to maintain a predetermined relation between said cutter and tool.

In testimony whereof I affix my signature in presence of two witnesses.

FRANZ' LOUIS WAGHTLER.

Witnesses:

RICHARD Trrnn'rn, GUSTAV MI'iLLER.