US1559206A - Grinding machine - Google Patents

Description

" Oct. 27, 1925- F. D. VAN NORMAN GRINDING MACHINE Filed Feb. 20 1920 4 Sheats-Sheet l INVENTOR ATTORNEYS.

Oct. 27 1925' F. p. VAN NORM N GRINDING MACHINE Filed Feb. 20, 1920 4 sums-shut 2 ATTORNEY6.

- 1,559,206 F. D. VAN NORMAN GRINDING MACHINE' Filed Feb, 20, 1920 4 Sheets-Sheet 3 INVENTOR ATTORNEYfi.

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Dct. 27.,

F. D. VAN NORMAN GRINDING MACHINE Filed Feb. 2.0, 1920 4 Sheets-Sheet 4 n l VENTOR ATTORNEYS.

Patented Qct. 27, 1925.

UNITED STATES? PA ENT .IOFFICE.

FREDERICK n. VAN NORMAN, or SPRINGFIELD, ASSACHUSET S.

GRINDING MACHINE.

Application filed February 20, 1920. Serial No. 360,096, I

' T 0 all whom it may concern:

Be it known that I, FREDERICK D. -V-\N NORMAN, a citizen of the United States of bodimentof the invention, chosen for illustrative purposes, is adapted for high speed precision grinding and is of the general type disclosed inU. S. Letters Patent No. 1,303,744, granted May 13, 1919, to Charles E. Van Norman.

The machine disclosed in said patent is characterized by the provision of means whereby the work may be quickly brought into offset relation with 'the'tool-for the purpose of testing, measuring, inspecting, or removingthe work, and whereby the work may he as readily returned to and locked in correct operating relation with, the tool. The work-carrying spindle in such machines is mounted for exceedingly free rotation and this. coupled with the consider-- able speed; at which the spindle rotates.

means that the work will revolve for a long timeevcn after it. is disconnected tronrits source of power.

An object of this invention is to provide. 'in a machine of this general class, means cause an additional retardation of the firstnamcd'spindle. 1

Another object of the invention is to providc a grinding machine of the general type described. which is entirely self-contained and with which the several overhead belt connections. usually nccc:-;.-'1ar r. are climi natctl.

Another object is to provide a compact 1nachine,'ot' the general type described,

which .will occupy a minlmum of floor space, and to extend the working range of such machines.

According to the last-named object, separate and longitudinally spaced pedestals are provided, one for the work head" and one for-the wheel head, and such pedestals are connected together bya common base portion, but ata level whichis a substantial distance below the bases of said heads.

. Such pedestals areso arranged as to afford between them a pronounced gap or depression which underlies both the work and tool in all their various positions and extends so far below their headsv that work of widely'varying diameter may be handled..-

By this improvement, I am enabled to obtain .a workingrange at least twice as great as that of any other machine, with of floor space.

.which I am familiar, for a given amount Anotherobject of the invention isto pro-' Vide in a grinding machine, wherein arotary spindle 1S carried=bya reciprocable slide. and wherein the driving means for such spindle is mountedin the supporting frame of the machine, compensating devices associated with the connections between said means and spindle tomaintaina uniform driving engagement with the spindle at all points in itsrange of travel.

A further ohj'eet'of the invention is to provide in a grinding machine having a rotary spindle mounted-in a slide which lie movable both longitudinally and trans-- vcrsely, a driving means for the spindle mounted in the supporting frame of the nrichine. and compensating devices associated with theconnections between said means and spindle to maintain a uniform driving connection therewith at all times and yet permit free movement both longitudina ly and transversely.

A further object of the invention is to provide in a grinding machim generally improved mechanical.structure. t

other objects and advantages will appear in the following description and in the illustrative embodiment of the invention in the accompanying drawings, in which,

Fig; 1 is a'front elevational view of a machine embodying the invention; t

Fig- 2 isa plan view thereof;

I tional elevation taken on the line l1l1 of Fi 2.

Re erring to these drawings; the machine includes a main supporting frame which comprises three distinct parts wviz, two separate and longitudinallyspaced pedestals A and B which are'connected by a base portion C. The top surface 1) of the connecting portion C is, however, a substantial distance below the tops of the pedestals Afllld B and leaves a gap or depression jE between them of substantial The adjacent surfaces of the pedestals and B Tare prefarably vertical, or substantially so, and these surfaces, which form wallslof the gap E are extended laterally beyond the pedestals, as indicated at]? in Fig. 4 to make the width of the gap at least substantially coextensive with the travel ofthe work head which, as will appear, is slidab'le transversely on pedestal A. i v v The pedestal B is provided with longitudinally directed wags {Fig 5) which slidably support a sli e, or carriage H and which extend from one end of the; ,edestal to the other, It ,is to be noted part cularly that the left face of pedestal B does not .project beyond the left end the ways G, so that a free, unobsti' ucted space is. left to permit free movement of the grinding wheel, both longitudinally and crosswise, through the desired ranges, even ;t hough the wheel is far greater 'infsi'zethan shown.

The crosswise movement, of the wheel, necessary for crossafeeding purposes, is ac.-

complished by relatively slow acting means of any suitable characters Thus, the wheel I, which is mounted :on a tool carrying spindle J, rotatably mounted in a whe el head or sub-slide K, slidable crosswise on slide H, may be moved 'sby screw] (conventionally indicated at L infa Well-"known manner. Scnew L maybe manually moved by means of the hand; wheel M or :by any ,,.'oths=r suitable means, as ('lesired. The cross feeding movement of the wheel may be automatically accomplished, if desired, as disclosed in the aforesaid patent.

The main slide, or carriage such gear meshes witilr-a rack PfiXtitl to the H, is longi-' tudinally reciprocable and may be reciprounderside of carriage H, all as indicated in Fig. 5. Obviously, any other suitable means may be employed, as desired, for actuating th a slide H and the invention is independent of the particular means employed. The slide H may be automatically actuated, as will later appear.

The pedestal A is extended laterally beyond pedestal B and is provided with ways Q which extend in a direction at variance with ways G and usually, although not necessari lly, transversely to the latter as shown. he ways Q slidably support a slide R and such slide carries a work head S, which is preferably angularly adjustable on slide R, as indicated, and as more fully disclosed in the aforesaid patent. The workhead S rotatably supports a spindle T which carries at one end a chuck U, or any other suitable work-supporting means. The work is indicated at V.

The, slide Bis movableby quick-acting means to bring the work V and tool I into offset relation. The means by which this result is accompli sh"d are substantially those of the aforesaid patent and therefore require no extended description here, reference being made to such patent for a more complete disclosure. Briefly, a rack W, fixed to ways Q, is engaged'by a gear X which'is supported in slide R for rotation about a vertical axis and is movable by a handle Y. Associated with handle Y is a latch Z which cooperates with a shoulder Z (preferably adjustable as indicated) to hold the work V in operating alignment with the tool I. Although the engagement'ofthe parts Z and Z hold the slide R from movement only in one direction, additional means like those of the aforesaid patent are employed so that when latch Z vengages shoulder Z the slide R is positively held from movement in either direction.

Obviously, the important result aimed at by the mechanism just described, is the rapid separation of the work and tool and 7 "thus affording opportunity for the free the provision of a machine, which is entirely I self-contained and eliminatesthe usual overhead belt connections. Thus, the source of power may advantageously, although it need changin not necessaril be, an electric motor in, which is fixed to the base portion of the main supporting frame, the portion C of the latter being made hollow for this purpose. The drive-shaft of motor m carries a ulley l and such pulley is connected by a belt 11 to a pulley 12 on a countershaft 13, which is rotatably supported from and extends along the rear side of the support ing frame. The countershaft 13 is connected through the intermediary of speed-v devices with a second arallel counters aft 14, also mounted in t e supporting frame. The speed-changing devices referred to may be of any suitable ty e and an example of one type 1s shown in and 3, wherein oppositely-arranged stepped pulleys l and 16 on shafts 13 and 14, re-

'. spect ively, are connected by a. belt 17. Ob-

viously, the pulley 12 might be driven from an external source of power, if.-'desired.

Both of the rotary spindles J and Tare -driven from the countershaft 14 and the tool-carr ing spindle J is driven therefrom in the fo lowing manner. Rotatably mounted upon and along the rear side of the supporting frame and above the shaft 13, is a shaft 18 which carries an elongated pulley or drum 19 of a length coextensive with the travel of slide H. Shaft 18 carries a pulley 20 which is connected by a belt 21 to a u ley 22 on shaft 14. The drum 19 has It and pulley connections to a pulley 23 on the rotary spindle J, but due to the cross-feeding movement of this spindle, it is necessary to 'interpose compensating devices to provide at all times a uniform driving connection for the spindle irrespective of its transverse travel. Such compensating devices, as illustrated, take the form of spring-actuated idler'pulleys, which properly tension the drivingbelt at all times.

For example, an arm 24 is pivoted, to the.

supporting frame at 25" and preferably carries two idler pulleys 26, one for engagement with each lap of a belt 27 which connects the drum 19 to a pulley 28. A spring for belt 32, for these pulleys are mounted on one end of an arm 33 which is ad'ustably secured at its other end to the sli eK at 34. Thus, arm 33-is angularly adjustable to vary the center to center distance 'nected by a be between pulle s 23 and 31 andthus ad'ust the tension o belt 32. The tension of elt 27 is, of course, adjustable by the device 30. The countershaft 14 drives the spindle T in the following manner. On the end of shaft 14 whichpro'ects beyond the left end of the supporting rame 1 (as viewed in Fig. 1) is fixed a stepped pulley 35 which is cont 36 to a. similar pulley 37 fixed on a hollow sleeve 38 rotatably sup ported inthe'supporting frame, as shown in Fig. 6. .Mounted on sleeve 38 for free rotation and held from axial movement between thepulley 37 and a collar 39 on the sleeve is ialpulley 40, which is connectible with and disconnectible-from pulley 37 by a suitable clutch, as will appear. Pulley 40 is connected'by a belt 41 to a pulley 42 on'spindle T. 'Since the latter is adapted for-transverse sliding movements, it is essential to provide compensating devices to maintain'a uniform driving engagement for spindle T irrespective of its position in its transverse travel. Such compensating devices comprise anidler pulley 43 engageable with one lap of belt 41 andmounted in one end of an arm 44, which is pivoted interme- I dite its ends at 45 to the supporting frame and yieldingly connected at its other end by a'spring'46' (preferably adjustably as indicated at" 47) to such frame.

Any suitable means may beemployed for connecting and disconnecting the pulleys 37 and 40 and that particular means, shown in Figs. 6 and 7 and now to be described, is given merely for illustrative purposes. That end face of pulley 40 adjacent pulley 37 is bored out to receive a split ring 48 and radially slidable insleeve 38 and in a collar 49 thereon is a wedge block' 50, the pointed outer end of which engages between and is adapted to spread the ends of ring 48. and force it tightly against pulley 40. The band 48 is fastened at its mid point to collar 49. Thus, when the ends of band 48 are spread, the .pulley- 37 will drive pulley 40. The wedge-block 50 rests upon a wedge-like surface formed on a rod 51 slidahle in sleeve 38. A circumferentiallygrooved collar. 52, fixed on theinner end of rod 51. .is engaged by the forked lower end of a lever 53 which is fixed to a shaft 54 (see Fig. 1). On shaft 54 is an operating lever 55 which, when in the position shown. causes the ring 48 to expand and connect the pulleys" 37 and 40. Lever 55, when swung to the right causes the disconnection of pulleys 37 and 40.- The lever 55 may be operated manually. if desired, or automatically as will later appear.

It is desirable in many instances when the'work V is moved into offset relation with the tool I, to disconnect the work from its driving means in order that the work may he brought to rest for inspection, measurement or removal. The clutch just de scribed permits this result, but the spindle T. which is mounted to rotate very freely, usually on antifriction hearings, will not immediately come to rest even when disconnected from its driving means. To eliminate waste time in waiting for the spindle T to come to rest, additional means are provided to automatically retard the spindle when it it moved into offset relation with the tool. Such means may be of any suitable character and as an illustrative e ample of one of many ways of accomplishing the desired result, reference is made to Figs. 1 and 4. Thus. a brake drum 56 may be fixed to spindle T and may, as shown. be advantageously formed as a part of the pulley 42 itself, the outer face of such pulley also being so formed to provide a hand-wheel 57. if desired. Pivoted at one end at 58 to the work head S is a substantially semi-circular brake hand 59. heother end of band 59 is connected by a flexible member, as a chain 60, to one end of a lever 6 and preferably there is interposed in the flexible member 66 a yi eldable member. as a spring 62. The lever 61 is pivoted inte mediate its ends to the slide R and. preferably. through the intermediary of a bracket 63 which is connected to the slide bv bolts 64. the heads of which are received in a T-slot 65 formed in slide R. The lower end of lever 61 is arranged in the path of an abutment 66' secured, preferably in an adjustable fashion by means of the bracket 67 and holt-and-slot connection 68, to the pedestal A. Thus, as slide R moves to the right (as viewed in Fig. 4) the lower end of lever 61 will e entually engage abutment 66. and continued movenient of the slidewill cause pressure of band 59 on drum 56. Continued movement of slide R causes increasing pressure of the band on the drum. although the tension of spring 62 may be so adjusted as to yield when the braking pressure exceeds a predetermined degree. Preferably. the braking pressure is not such as to firmly hold drum 56 against rotation. for when the work is in offset relation with the tool. the operator frequently wishes to turn it bv hand to difi'erent angular positions. The degree of braking pressure may be also controlled by adjustment of the brackets 63 and 67. either relatively to the other. and so also may the time when the braking pressure is applied.

Preferably. the disconnection of the drive for spindlc T is accomplished. as by an opening of the clutch described. -or otherwise slightly in advance of the application of the braking means. To insure this result. the movement of slide R. which causes the application of the braking means, may advantageously he also made to cause the disconnection of the drive for spindle T.

Thus, for example, the abutment 66 serves as the pivot for a lever 69, the lower end of which is so connected to the described lever as to throw the latter to the right when slide R is moved toward otfset position. The upper end of lever 69 is camshapcd and lies in the path of an abutment 7 on bracket '63. The arrangement is such that lever will be engaged and moved by abutment 76 just shortly before the lever 6 engaries the abutment 66, the levers 61 and being offset to swing without interference as indicated in Fig. 1.

The connections between the levers and 69 may be of any suitable type and, as an illustrative example, reference is made to Figs. 1 and 4-. At that corner of pedestal A adjacent lever 69, there is pivotally mounted on avertical axis a bell crank having two arms 71, and 79,. Arm 71 is connected by a link 74 (preferably adjustable for length) to the lower end of lever 69. Arm 72 is connected by a link 75 to a rocker arm 76 pivoted to pedestal'A and the arm 76 is connected by a link 77 (preferably adjustable for length as indicated) to lever 55. Thus, as lever 69 is moved by abutment 70, lever 55 is swung in the right direction to open the clutch described. This clutch is of such a. type that the parts, once disengaged, remain in disengaged position. Thus, the member 51 and all connected parts, as levers 55 and 69, remain in the positions to which theyare moved. Therefore, the upper end of lever 69, which is engaged by and moved out of the path of abutment 70, may be, but is not necessarily, engaged by the latter on a return stroke of slide R.

The rocker 7 6 is provided with a hole 73 in case it is desired to move slide R in the opposite direction to that described and still ettect the same results. In such case, link 75 would be shifted from the upper end of arm 76 to the hole 73 and lever 69 would be moved relatively to bracket 63 to the left of the latter. to the left (Fi 4) the clutch would be opened and the brake applied, as heretofore described.

It has been mentioned that the slide H may be automatically moved and an illustrative example of one of many suitable ways, which will readily occur to those skilled. in the art, for accomplishing this function is shown in Figs. 5, 8, S), and Lt). Thus, the main slidc. It is provided with a portion /z, which depends between ways (i and affords a longitudinal slidcway for a. subslide I). The. latter may be locked to the main slide, when automatic feeding of the latter is desired, by a wedge block 0, which engages in a recess in sub-slide 7) as shown in Fig. 9. Block (1 is carried on the lower end of a rod (Z slidably mounted in slide 1'1 and yieldingly urged by a spring (4 toward Then on a movement of slide R necting'rod 2', the other end of the latter Subsli'de b. Ordinarily, when slides H and Z) are moved relatively to one another the block a will automatically engage in the re cess in sub-slide b and lock the two together. To prevent such action, a lever f, fixed to red (I. is provided with a cam which coacts with a fixed cam I! on slide 11, to raise the block 0 free from sub-slide b.

Sub-slide b is connected, preferably adjustably as indicated, to one end of a 'conbeing received on a crank pin j (Fig. 10). Such pin is carried by a slide hadjustable (by means of a screw, conventionally indicated at Z') longitudinally on an arm n. The latter is pivoted at one end at 7) (Fig. 5) and at the other end carries a roll 7" for engagement by a cam s. The arrangement, thus briefly described, is a well-known one for converting rotary intoreciprocating movement.

Cam 8 is fixed to a vertical shaft t mounted within the hollow base frame and driven by a worm gearu from a worm o. The latter is fixed to a shaft in which carries a pulley 00, all as indicated in Fig. 3. Pulley as is driven by a belt from a pulley 81 fixed to a stepped pulley 82 which is mounted for free rotation on the countershaft 14 described. Freely rotatable on a stud 83 on frame C (Fig. is a double stepped pulley, one portion 84 of which is adapted for connection to pulley82 by a belt 85 to drive the latter at various speeds. The other portion 86 is connected by a belt 87 to a stepped pulley 88 on the described shaft 13. Thus, by means of the various speed changing devices described, slide H may be driven at various speeds and at relatively slow speed, as desired for feeding purposes.

While it is not essential that the hand wheel N (used for manually feeding slide H) be disconnected when the automatic feed is used, it is generally desirable so to do in order to prevent the possibility of the handle (which would otherwise rotate) injuring the operator or his clothes. This is readily accomplished as shown in Fig. 11.

The hand wheel N, which is arranged to turn the gear 0, is loosely rotatable on a shaft 90, which in turn is rotatably mounted in a bracket 91 fixed to pedestal B and which is fixed to the gear 0. A collar 92, on shaft 90, cooperates with the bracket 91 to prevent axial displacement of handwheel N. The latter is provided with a keyway 93 and the shaft carries a slidable key 94 to engage therewith. Key 94 is fixed to a rod 95 slidable in shaft 90 andprovided with a knob 90 on its outer end for convenient actuation. The key 94 extends radially through a slot 97 in shaft 90 and its outer end is freely rotatable in a counterbore 98 in bracket 91. With the parts in between the elements 100and 101.

It is frequently desirableto provide stops for limiting! or defining the limits of, travel of the tool I relatively to the work V. Generally, it is the forward stroke of the tool (the cutting; stroke) which requires the stop, as the precise position of the tool at the end of its rearward stroke is. generally immaterial. For example, in finishing hollow work, as-by grinding the internal .periphery of the hole therein,a stop to limit the inner travel of the wheel is desirable to control the depth of the hole. So also when the work is faced off. as by moving the slide R by means of lever Y, it is desirable to limit the relative movement of wheel and work toprevent, in the present case, en-' and 101 limits the extreme outward movement of slide H and may be used for de-' termining the depth of the hole to be ground; A distance piece 102 is provided, which is loosely carried by an arm 103 pivoted to-a rod 104 carried by slide H, and this arm 103 may be swung downwardly at option, to interpose the distance piece 102 The function of the distance piece is to position the slide H for the performance of a secondary operation, as for example, the finishing of the outer end face of the work V. Distance pieces of various types and lengths may also readily be substituted to effect various results. For controlling the relative transversepositions of the tool and work, as for an end facing operation, a similar arrange-' ment is employed, as indicated in Fig. 1, wherein 105 representsthe fixed stop, 106 the adjustable abutment, 107 the distance piece, and 1.08 the pivoted arm. Where, as here, the end facing operation is performed by moving the work-carrying slide R, the stop 105 is fixed to pedestal A and the other elements are carried by slide R. a

The operation of the machine will vary according to the nature of the work to be performed and, in the usual aspects, will readily be understood from the foregoing description by those skilled in the art. 0 The operation of the unusual features of the invention, as the provision for rapidly ofilee setting the work and tool for the purpose of test, inspection, assembl or removal of work, and the provisions .or retardm the rotation of the work at such a time, ave been explained in the foregoing description, together with the operation of the compensating devices and the auxiliary stops.

Aside from these features of the inven tion, a most important feature is the peculiar arrangement of parts which permits a very substantial increase in working range without any increase in floor space, the advantages of which will be readily apparent to the manufacturer. I obtain these advantages by the provision of separate pedestals for the work head and tool head, which permit of the pronounced depression between the two to provide the desired wide working range which permits work of widely varying diameter to be handled. While obtaining the advantages described by the use of separate pedestals, I recognize the practical necessity forrigidly connecting them so that they are not independent. That is, a rigid common support for the pedestals is a necessity in a grinder intended for high speed precision work. The advantages of rigidity of the Work and wheel heads have been'retained and yet the supporting pedestals therefor have been separated as much as possible, without sacrifice to rigidity, to obtain the other important results described. The invention has been disclosed herein in a single form for illustrative purposes. It is recognized, however, that many other forms and arrangements will readily suggest themselves to those skilled in the art, having for their object the use of the invention in a specific form differing from that disclosed. It is, therefore, desired to have the scope-of the invention determined by the appended claims interpreted by the spirit of the present disclosure rather than in the letter of the exact form disclosed.

IVhat I claim is:

1. In a grinding machine, aligned rotary workholding and tool-holding devices. quick acting means to move one of said devices into offset relat on with the other, driving means for said movable devices in cluding means associated with the driving means to maintain a uniform driving connection therewith throughout its range of movement.

2. In a grinding machine, a work head and a wheel head, a supporting frame for said heads, a rotary spindle mounted in each head. one of said heads being movable on said frame in directions parallel to and at an angle with the axis of the spindle in the other head, driving means for the spindi in said movable head including compeneating means movable in one direction with the movable head, whereby uniform driv- 3. In a grinding machine, aligned rotary.

work-supporting and tool-holding devices, quick acting means to move one of said devices into offset relation with the other, driving means for said movable device, and mechanism operable on such movement to connect or disconnect said driving means.

' t. In a grinding machine, aligned rotary \vork-supporting and tool-holding devices, quick acting means to move one of said devices into offset relation with the other, driving means for said movable device including means associated with the driving means to maintain a uniform driving connection therewith throughout its range of movement, and mechanism operable on such movement to connect: or disconnect the driving means for said movable device.

5. In a grinding machine, a work head and a Wheel head, a supporting frame therefor, a rotatable spindle mounted in each head, one of said heads being movable on said frame in directions parallel to and at an angle with the axis of the spindle in the other. driving means for the spindle in the movable head mounted in said frame. said driving means including compensating means for maintaining a uniform driving connection with the movable spindle at all positions in its range of travel. and nieans for automatically feeding the movable head inoue of its directions of movement relative to the supporting frame.

6. In a grinding machine. a work head and a wheel head. a supporting frame therefor. a rotatable spindle mounted in each head. one of said heads being slidable on said frame in directions substantially parallel to the axis of the spindle in the other head and also at substantially right angles thereto. driving means for the spindle in the slidable head mounted in said frame, said driving means including compensating means for maintaining a uniform drivin. connection with the slidable spindle at all positions in its range of travel; and means for :uitomaticallv feeding the slidable head in one of its directions of movement relative to the supporting frame.

7. In a grinding machine, a supporting frame, two separate slides mounted thereon for horizontal travel in different directions. a rotary spimllerarried by each slide. driving means mounted in said frame. and connections from such means to each spindle including con'ipensating means for main taining a uniform driving connection with the spindles at all positions in their ranges of travel, and means for both manually and automatically feeding one of said slides in a horizontal direction relative to said frame.

8. In a grinding machine, a work head and a wheel head, a supporting frame therefor, a rotary spindle mounted in one of said heads, the last-named head being movable both longitudinally toward and away from the other and in substantially transverse directions, driving means on said frame, and connections between such means and said spindle includ'ng devices to permit longitudinal and transverse'movement thereof and maintain at all times a uniform driving connection for the spindle, and means for automatically feed i'igsaid wheel head in one directionrelative to said frame.

9. In a grinding machine, a supporting frame,a work head and a wheel head thereon and mounted for relative movement toward and away from one another, one of said heads being movable in a direction transverse to the first-named movement, a rotary spindle in the last-nan'ied head, a pivoted arm movable longitudinally with the latter, idler pulleys thereon. connections between one of such pulleys and the spindle, driving means for the spindle mounted in said frame, connections between the other pulley and said driving means, and a yieldingly actuated idler pulley associatedwith the last-named connections to maintain. a uniform driving connection with the spindle at all points in its transverse travel.

10. In a grinding machine, a supporting frame, a work head and a wheel head thereon and mounted for relative movement toward and away from one another, one of said heads being movable in a direction,

transverse to the first-named movement, a rotary spindle in the last-named head, an arm pivoted to the latter, idler pulleys thereon, connections between one of such pulleys and the spindle, an elongated drivin; pulley mounted in the frame, connections between the latter and the other pulley on said arm, and a yieldingly actuated idler pulley associated with the last-named connections to maintain a uniform driving connection with the spindle at all points in its transverse travel.

11. In a grinding machine, a supporting frame, two separate slides thereon, rotary work-supporting means on one slide and a tool-carrying spindle on the other, means for moving one slide relatively to the other for feeding the tool longitudinally and transversely relatively to the work, quickacting means to move the other slide to bring the work and tool into off-set relation and means operable as the work and tool, the one relatively to the other, are brought toward their positions of offset relation to retard the rotation of the work-supporting means.

12. In a grinding machine, a supporting frame, .two separate slides thereon, rotary work-supporting means on one slide and a tooLcarrying spindle on the other, means for feeding the tool longitudinally and transversely to the work, quick-acting means to ll'lOYO the work-carrying slide to bring the work and tool into offset relation, driving means for the work-supporting means, means to disconnect the driving and worksupporting means, and means operable as the work is moved toward its offset position to retard the rotation of the work-support ing means.

13. In a grinding machine, aligned rotary work-supporting and tool-holding devices, quicl -acting mechanism to move one of said devices into offset relation with'the other, and mechanism operable on such movement to retard the rotation of the device thus moved.

14. In a grinding machine, aligned rotary work-supporting and tool-holding devices, quick-acting mechanism to move one of said devices into offset relation with the other, and means to disconnect and retard the rotation of the said device.

15QIn a grinding machine, a supporting frame, a rotary work-supporting device, a slidefor the latter movable on said frame, a rotary toolholding spindle movable longitudinally with respect to said device, slowacting crossfeeding mechanism for said spindle, quick-acting means to move the work-supporting device into offset relation with the spindle, means operable to retard the rotation of said device as it is moved into offset relation with the spindle including devices one on said slide and one on said frame and engageable on movement of the slide, and means permitting one of said devices to be moved relatively to the other.

16. In a grinding machine, a supporting frame, a rotary work-supporting device, a

slide for the latter movable on said frame, a rotary tool-holding spindle movable longitudinally with respect to said device, slovv acting cross-feeding vmechanism for said spindle, quick-acting means to move the work-supporting device into ofiset relation with the spindle, means operable to retard the rotation of said device as it is moved into offset relation with the spindle including devices one on said slide and one on said frame and engageable on movement of the slide, and means permitting each of said devices to be moved independently of the other. I

17. In a grinding machine, a supporting frame, a slide thereon, a rotary Work-carrying spindle in said slide, a brake drum on such spindle, a brake band cooperating with the drum and suported on said slide, and means for applying the band to the drum including a lever pivoted to said slide and an abutment on said frame engageable by said lever on movement of the slide.

18. In a grinding machine, a supportin; frame, a slide thereon, a rotary workcarryin; spindle in said slide. a brake drum on such spindle, a brake band cooperatin; with the drum and supported on said slide, and means for appl vin.; the band to the drum including a lever pivoted to said slide and an abutment on said frame engageable by said lever on movement of the slide together with a yieldable connection between said lever and band.

19. In a grinding machine, a tool-carrying spindle, rotary \vork supporting means, drivinn mechanism for the latter, quick-acting means to separate the spindle and worksupporting means to brine them into offset relation, and means operable on such separation to disconnect the work-supporting means from its driving mechanism.

20. In a grinding, machine, a tool-carrying spindle, rotary Work-supporting means, driving mechanism for the latter, quick-acting: means to separate the spindle and work supporting means to brine them into offset relation, and means operable on such separation to disconnect the work-supporting means for its driving, mechanism, and apply asaeoe a retarding force to the disconnected worl supporting means.

21. In a grinding machine, aligned rotary work-holding and tool-holding devices, quick actin means to move one of said devices into offset relation ,Wlilll the other, means for moving one of said devices axially toward and away from the other, means for driving said devices including means associated with the driving means for one of said movable devices to maintain a uniform driving connection therewith during its movement.

22. In a grinding machine, a work head and a wheel head, a supporting" frame for said heads, a rotatable spindle mounted in each head, one of said heads bein e movable on said frame in directions parallel to and at an angle with the axis of the spindle in the other, driving means for the spindle in the movable head comprising a drum substantially coextensive in length with the. longitudinal travel of the movable head, and compensating means movable in one direction with the movable head whereby driving; force may be transmitted uniformly to the spindle in the movable head in any one of its various positions.-

FREDERICK D. VAN NQRMAN.

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