US2429250A

US2429250A - Grinding machine

Info

Publication number: US2429250A
Application number: US491824A
Authority: US
Inventors: Christy A Wiken; Eric A Reibig
Original assignee: Rockwell Manufacturing Co
Current assignee: Rockwell Manufacturing Co
Priority date: 1943-06-22
Filing date: 1943-06-22
Publication date: 1947-10-21
Anticipated expiration: 1964-10-21

Description

Oat.v 21, 1947. c. A. WIKEN El AL 2,429,250

GRINDING MACHINE v Filed June 22, 1945 1s Sheets-Sheet 1 M J MWS Ot. 21, 1947. c. A. WIKEN ET AL 2,429,250

GRINDING MACHINE Filed June 22, 1943 13 Sheets-Sheet 2 M KM Oct. 21,' 1947. c. A. WIKEN ET AL GRINDING MACHINE Fi1ed.June 22, 1943 13 Sheets-Sheet 3 5 MV 5. A W W PM.

Oct. 21, 1947. 'C, MKEN ET AL 2,429,250

GRINDING MACHINE Filed June 22, 1943 l3 Sheets-Sheet 5 In f w HL .z -ZU. Z 24 i 69 z; mmml 7/ 4W5) 2! i; 7

CirzisyAQ men Eric/126%? Oct. 21, 1947. c. A. WIKEN ET AL 2,429,250

GRINDING MACHINE Filed June 22, 1943 13 Sheets-Sheet 6 Oct. 21, 1947. c. A. WIKEN ET AL eimmme MACHINE Filed June 22, 1943 13 Sheets-Sheet 8- GRINDING MACHINE l3 Sheets-Sheet 10 Filed June 22, 1943 och-21', 1941. c, A, KEN m 2,429,250

GRINDING MACHINE Filed JQIIG 2 2, 1943 I 13 Sheets-Sheet 11 Oct. 21, 1947.. c. A. WIKEN El AL GRINDING MACHINE Filed June 22, 194:2: 13 Sheets-Sheet 12 WMZM MNMMN Oct. 21, 1947. c. A. WIKEN ET AL GRINDING MACHINE l3 Sheets-Sheet 13 Filed June 22, 1943 Patented Oct. 21, 1%47 stares GRINDING MACHINE Application June 22, 1943, Serial No. 491,824

9 Claims.

The present invention relates to machine tools and is more particularly concerned with grinding machines having a device for carrying a rotary tool, supported on centers, past a grinding wheel for sharpening the cutting edges, although it is not limited to such use, inasmuch as certain features are capable of advantageous utilization in other machines.

Although machines of this general character have been heretofore proposed, and some of them have gone into use, they are complicated and costly, and moreover are of special construction, embodying a permanent headstock and tailstock assembly adapting the machines solely to the grinding of work between centers, and by reason of their design they cannot be successfully utilized to carry out other grinding operations. It has accordingly been impracticable for the owner of a small shop to make the substantial invest ment required to purchase the prior tool and cutter sharpening machines, especially since they would be idle except when tool or cutter sharpening jobs were actually being carried out. Small shops have therefore sent out their tool and cutter sharpening work to shops having special machines designed for that purpose.

It is accordingly the primary object of this invention to provide a grinding machine having a tool holder assembly for carrying a tool or cutter past the grinding wheel, which will accurately hold the tool in proper position during grinding, permits readly indexing of the tool, to successively present its cutting edges of the wheel, and is so designed that the tool holder assembly may be completely removed and the machine employed for surface or other classes of grinding operations.

A further important object is to provide a tool holding and centering device which is so designed that it may be installed on the tables of existing grinding machine as an attachment, will rigidly and accurately hold tools in proper grinding position, may be readily removed to restore the grinding machine to its original condition, and yet which is of low cost, rugged construction.

Another object is' to provide an auxiliary table assembly, embodying centers for holding a tool, with a pilot assembly adapting it for secure mounting on the tables of existing grinding machines, in any one of a plurality of angular adjusted positions about an axis normal to the table surface, for sharpening tools having diflerently inclined cutting edges.

A further object is to provide an auxiliary table adapted to be installed on the flat table of existing grinding machines and having flat accurately-formed bearing surfaces on its lower side adapted to rest on the table and a fiat top hearing surface on its upper side adapted to adjustably support a headstock and a tailstock, the bearing surfaces lying in parallel planesand the auxiliary table having no portions lying outside those planes, whereby the table may be accurately finished in a simple surface grinding operation, eliminating hand finishing.

Another object is to provide a tool holding assembly embodying a, headstock and a tailstock which are of substantially identical construction, it being only necessary to interchange certain minor parts to convert one to the other.

A further object is to provide a grinding machine, having a table movable in a horizontal plane under the wheel, with a novel guard assembly, embodyin an adjustably pivoted arm and a plurality of guards adapted for interchangeable installation on the arm, so as to emciently guard the wheel irrespective of the type or size of wheel that may be installed in the machine.

The invention further aims to provide a tooth stop device comprising a novel assembly of parts which may be interconnected in a plurality of difierent relationships to correctly cooperate with the teeth or other projections of the various types and sizes of tools or cutters to be ground, and yet which permits ready indexing of the tool to successively present'its cutting edges to the grinding wheel.

Another object is to provide a, grinding machine, having a table reciprocable with respect to the wheel, with a center device for holding a tool, and a tooth stop device for successively stepping the tool about its axis to present its cutting edges to the wheel and to provide means for mounting the tooth stop device either stationarily upon the machine or upon the reciprocable table, to achieve the desired tooth-stopping action.

Additional objects are to provide improved headstock and tailstock assemblies, and other grinding machine improvements and refinements to be hereinafter pointed out.

Further objects will become apparent as the specification proceeds in conjunction with the annexed drawings, and from the appended claims.

In the drawings:

Figure l is a perspective view of the grinding apparatus of the invention, showing-a side milling cutter in grinding position thereon;

Figure 2 is a similar view of the apparatus, showing a, hand reamer in place-on the machine;

Figure 3 is a front elevational view of the wheel guard mounting frame. showing a small diameter cup wheel guard in operative position thereon;

Figure 4 is a vertical sectional view through the guard and mounting assembly of Figure 3, looking in the direction of the arrows, the wheel being shown in broken lines;

Figure 5 is a view similar to Figure 3, but shows a large diameter disc wheel guard in place;

Figure 6 is a vertical sectional view through the apparatus of Figure 5;

Figure 7 is a top plan view showing the auxiliary table assembly of the invention in place on the main grinder table, with parts broken away and in section to more clearly illustrate the structure;

Figure 8 is a front elevational view of the device shown in Figure 7, parts being broken away and in section to illustrate certain details of the structure;

Figure 9 is a vertical sectional view on an enlarged scale, taken substantially on the line 9-9 of Figure 8:

Figure 9a is a fragmental sectional view illustrating the manner in which the tailstock is guided on the auxiliary table;

Figure 10 is a vertical sectional view on an enlarged scale, taken substantially on the line ill-l 0 of Figure 8;

Figure 11 is an exploded view of the parts of the tooth rest of the invention;

Figure 11a is a perspective view of a modified form of stop finger for use with the assembly of Figure 11;

Figure 12 is a longitudinal sectional view illustrating certain parts of the tooth rest;

Figure 13 is-a perspective view showing a spiral cutter mounted on the apparatus of the invention by means of a mandrel;

Figure 14 shows the machine with the side milling cutter of Figure 1 in place thereon, but illustrates the parts from a different angle;

Figure 15 is a perspective view showing the side milling cutter of Figures 1 and 14 in place on the machine, and with the auxiliary table swung through 45 to present the bevel side edges of the cutter to the wheel;

Figure 16 is a perspective view of the device shown in Figure 15;

Figure 17 is a perspective view with a form cutter in place on the machine of the invention and with a dish wheel and dish wheel guard installed;

Figure 18 is a side elevational view, with parts in section, of a headstock of modified form, also forming part of the invention; 1

Figure 19 is a view similar to Figure 18 showing a modified form of tailstock also forming part of. the invention;

Figure 20 is a top plan view with parts broken away and in section showing the auxiliary table equipped with a fine adjustment device forming part of the invention; and

Figure 21 is a vertical sectional view through the device of Figure 20.

With continued reference to the drawings, wherein like reference characters have been employed to designate similar parts throughout the several views thereof, and referring first to Figure 1, the grinding machine to which the invention has been applied comprises a base 9, carrying an upright column II, on which a grinder head i2 is mounted for vertical adjustment by means of a screw 13 and a hand wheel I4. Mounted for rotation in a grinder frame III, which is rockably carried by head l2, and driven by a motor (not 4 shown) is an arbor assembly I6, carrying a grind-.- ing wheel l1. a cup type grinding wheel being shown installed in Figures 1 and 2. A micrometer screw I8 is employed to adjust grinding frame Ill up and down with respect to head l2.

Mounted for movement in a horizontal plane toward and away from column H is a table slide l9, adapted to be actuated by a hand wheel 2|, the latter being carried by a screw (not shown) which is threadedly connected to the table slide. Mounted for sliding movement on the table slide at right angles thereto, and actuated by means of a hand wheel 22, is a table 23, having a flat work supporting surface 24 and a longitudinal T- slot 25.

Movement of table 23 is limited in both directions by means of a pair of stop brackets 26 carried by a rod 21 mounted on the table, and cooperating with a stop screw 28 carried by a boss 28 on slide member IS.

The grinder structure so far described is fully disclosed and claimed in our co-pending application, Serial No. 467,512, filed December 1, 1942, for Machine tools," which is now Patent No.

2,386,283, issued October 9, 1945, and which may be referred to for a more detailed disclosure thereof.

We have found that, by providing a pilot member A, rigidly anchored to the grinder table, and auxiliary table B, carrying a headstock C and a tailstock D, and mounting a tool rest assembly E upon either the auxiliary table or the main grinder structure, it is possible to convert the surface grinder of the aforementioned application, or similar grinders, into a tool and cutter grinder which will accurately sharpen a wide variety of tools, thereby obviating the necessity of purchasing special machine and yet provid ing a structure which is of simple rugged design and which will turn out work of equal if not greater accuracy than the machines designed especially for tool and cutter sharpening purposes.

Referring to Figures 7 and 8, auxiliary table B is of elongated form and has a flat upper surface 3! and a ribbed and flanged lower surface.

Table B is preferably made of ordinary gray iron, and is of such design that the upper surface thereof may be finished in a simple surface grinding operation, there being no elements projecting above this surface. A longitudinal T-slot 32 extends longitudinally along the top of the table and is utilized to secure the headstock and tailstock in place in a manner to be hereinafter described. The central part of the underside of the table is provided with a pair of

ribs

33 and 34 defining a central space 35 to receive the pilot member A, and (as seen in Figure '7) the forward ends of

ribs

33 and 34 are curved to lie substantially concentrically with the pilot member. A second pair of

ribs

36 and 31 on the underside of the table, are concentric with the pilot member, and as seen in Figure 8 have their lower surfaces lying in a plane common with the lower edges of

ribs

33 and 34. All of the foregoing bearing surfaces are adapted to seat snugly against the upper side of work table surface 24. Depending from one side of the auxiliary work table at 01)- posite sides of the space 35 are flanges 39 and M and depending from the opposite side of the auxiliary work table are flanges 42 and 43, it being observed that

ribs

33 and 36 merge into flanges 39 and 42 and

ribs

34 and 3! merge into flanges 4| and 43. The ribs on the underside of the table also merge into a longitudinally extending boss 44, which (as seen in Figure 9) provides the required metal for forming T-slot 32. By reason of the interconnected webs and ribs, and the fact that the lower surfaces of

ribs

33, 34, 36 and 3'! are utilized as bearing surfaces engaging the top of the work table, an extremely strong and rugged table unit is provided, and one which transmits the cutting or grinding forces to the main table in such manner as to avoid any strains that would result in distorting or springing the parts sufliciently to impair the accuracy of the apparatus.

In order to facilitate finishing of top surface 3| of the auxiliary table in a simple surface grinding operation, a pair of lugs 45 are cast on its lower side and have their lower surfaces disposed in the same plane as the bearing faces of the ribs. "Accordingly, the auxiliary table may be so supported on the grinding machine during manufacture throughout its length by the ribs and lugs that it will not undergo distortion during the grinding operation. After manufacture of the table has been completed, lugs 45 may be removed if desired.

The novel manner in which the auxiliary table is held in place by the pilot member will now be described. Referring to Figures 7, 8 and 10, the pilot A is of generally disc-like form and is provided with a central opening 41 (Figure and a cylindrical periphery 48, carrying graduations 49 (preferably being divided up directly into degrees running from zero to 45 in each direction from the zero or parallel position of the tables shown in Figure 8. The pilot member is secured to the main work table 23 by means of a pair of T-bolts 5| having heads seating in T-slot 25 of the table and projecting upwardly through diametrically spaced openings in the pilot member. A pair of nuts 52, seating in a pair of recesses 53 in the pilot member, are turned on the T-bolts and frictionally clamp the pilot member to the main table. V

The pilot member is accurately positioned with respect to the main table by means of a pair of keys 55 secured in a longitudinal keyway 56 in the underside of the pilot member by means of cap screws 5'! and projecting partially into T-slot 25 adjacent each T-bolt 5|, as seen in Figures 8 and 10. Accordingly, by loosening nuts 52, pilot member A may be freely slid along the top of table 23, being guided by keys 55, and locked rigidly in any desired adjusted position by tightening nuts 52.

The auxiliary table is secured in place on the pilot member and work table in a manner seen more clearly in Figures 7 and 10. The auxiliary table and the pilot member are provided with aligned

mating openings

59 and 6|, respectively, and after manufacture and grinding of the auxiliary table is completed a trunnion or pivot plug 62 is frictionally fitted into opening 59 of the table, so as to pivotally project into opening 6| of the pilot member. If desired, the plug may alternatively be frictionally fitted into opening iii of the pilot member and disposed in journalling relationship with opening 59 of the table.

From the foregoing structure it is apparent that the pilot member may be locked in the proper longitudinal adjusted position on the table, (preferably in the central position illustrated in Figure 8, so that all of the ribs (33, 34, 3G and 31) may bear upon the upper table surface) and may be locked in place by nuts 52. Also, the auxiliary table is accurately journalled for rocking movement about an axis normal to the table surface. The auxiliary table is adapted to 5 be frictionally clamped to the main table, in any desired angular position, as follows.

Projecting through a pair of openings 64 in the auxiliary table and a pair of arcuate slots 65 in the pilot member, and having heads 66 seating in arcuate counter bores 67 in the pilot member, are a pair of bolts (i8. Nuts 69 on the bolts are adapted to pull the table down into tight engagement with the main table, it being observed in Figure 10 that when the parts are pulled up tight a clearance 1| exists between the lower face 12 of recess 35 of the auxiliary table, and the upper surface of the pilot. The provision of this clearance prevents the pilot from holding the auxiliary table with its bearing surfaces out of contact with the main table, it being understood that only a few thousandths of an inch clearance is necessary, and that if desired the clearance may be decreased by the use of shims. In order to locate nuts 69 below the top surface 3| of the auxiliary table, they are preferably disposed in recesses H3 at opposite sides of the table.

Secured to the front of the table adjacent front hold-down bolt 58, is a scale plate '25 by means of screws 16 having a reference line 11 cooperating with the graduations on cylindrical face 48 of the pilot member, it being understood that the holes in the plate are sufi'iciently oversize to permit the screws to be loosened and the plate adjusted by minor amounts in either direction to properly calibrate the machine, and when the adjustment has been obtained the screws are tightened to permanently lock it in position.

The auxiliary table is accordingly rigidly mounted upon the main work table, and by loosening nuts 69 the table may be rocked about the vertical axis of pilot trunnion 62, the desired angular position being secure by bringing the appropriate graduation on scale 48 into alignment with the zero reference line on plate 15. When the proper adjustment has been obtained nuts 69 are tightened, it being observed that, by reason of the clearance between the underside of the table and the pilot member, tightening of the nuts serves to directly pull the auxiliary table down into clamping engagement with the main table, with the bearing surfaces of

ribs

33, 34, 36 and 31 in frictional locking engagement with the main table. The manner in which the tools or cutters are adapted to be mounted on centers and presented to the wheel will now be set forth.

Referring particularly to Figures 7, 8 and 9, tailstock D is provided with a fiat face adapted for sliding engagement with the upper surface of the auxiliary table, and is guided for movement along it by a pair of keys 8i secured in a longitudinal recess 82 in the tailstock by a pair of screws 83, one key being located at each end .of the tailstock. As seen in Figure 9a, keys 8| project into the upper part of T-slot 32 and are snugly guided therein so as to maintain the tailstock square with the auxiliary table.

The tailstock is adapted to be frictionally clamped to the upper side of the table by means of a. single T-bolt 84, having a head seating in T-slot 32 of the auxiliary table, and a nut 85 bearing against the base of the tailstock. 'In order to line up the tailstock with the auxiliary table, it is provided with a pressure member 81 hearing against accurately formed faces 88 and 89 on the tailstock and the table respectively, it being observed in Figures 7 and 8 that, aside from the central break produced by front recess 13,

surface 89 extends throughout the length of the table, so that pressure member 81 may cooperate with it in any desired longitudinally adjusted position. A lug BI is also provided on the tailstock adjacent the pressure member for preventing it from tending to rotate and rock the tailstock out of firm engagement with the table. The pressure member is held in place by means of a thumb screw 92 threaded onto a stud 93 secured in the tailstock base.

It is accordingly apparent that the tailstock may he slid into any desired position along the table and when the desired position has been attained thumb screw 92 is tightened, so as to cause the tailstock to be pulled toward the front of the table. This action causes keys 8I to engage the front wall of T-slot 32, taking up any lost motion between the keys and the slot and accurately aligning the tailstocks with the longitudinal axis of the table by a T-square" action. Nut 85 is then turned home to' rigidly clamp the tailstock in place.

Mounted for reciprocation in the upper end of the tailstock is a center 95, urged toward work gripping or loading position by a. compression spring 96 seating against a cap 91 and adapted to be locked in place by a set screw 98. The center 95 is adapted to be retracted by means of an eccentric 99 seating in a transverse slot I M in the center and carried by a shaft I02 having a reduced portion I03. The shaft is adapted to be locked in place by a set screw and lock nut assembly I04 having a reduced end seating in groove I03. The shaft is adapted to be rocked by means of a lever I 05 secured to the end of the shaft. In the positions shown in Figure 8 the parts are in loading or work gripping position, and if desired screw 98 may be tightened to lock center 95. When it is desired to remove the work from the centers it is merely necessary to loosen screw 98 and rock handle I05 counterclockwise, which, through shaft I02, eccentric 99 and slot IOI, retracts the center against the action of spring 96. A lubricant fitting I 05 may be provided for admitting lubricant to the center and associated parts.

The headstock is supported upon and secured to the auxiliary table in a manner similar to the tailstock, and therefore similar reference characters, with the subscript c," have been employed to designate the similar parts and they will not again be described. The headstock is provided with a simple cylindrical portion I08 in which a center I09 is adapted to be locked in longitudinally adjusted position by a set screw II I.

Referring particularly to Figures 3, 4, 5 and 6, and referring first to Figure 4, grinder frame I is provided with an end face disposed substantially normal to the axis of rotation of the wheel, designated as I I2 in Figure 4, to which is secured, preferably by means of three screws II3, a dual purpose foundation or frame member II4, having a pair of arcuate slots I I and I I6 at its upper end and a pair of lugs I I1 and H8 at its lower end. The lugs are reinforced by angular webs H9 and they are each provided with an opening I2I for receiving a tooth-stop supporting screw, as will be pointed out hereinafter. Adapted for interchangeable installation in either slot H5 or slot H6 is a bolt assembly I22 carrying a. short crank arm I23 terminating in a forwardly directed pin or shaft I24. As seen in Figure 3, bolt I22 is provided with a square head I25 seating in an elongated recess I 26 in crank arm I23, so that nut I20 may be loosened and link I23 slid and rocked into any desired position with respect to bolt I22, and then looked in place.

Pin I24 is preferably tightly fitted into link I23 so as to be non-rotatable therein and is adapted to interchangeably support any one of a plurality of wheel guards. This appreciably widens the scope of usefulness of the machine because it permits either cup, or dished or peripheral grinding wheels of different diameters to be installed, as well as aifords a wide range of adjustabillty of the guards with respect to the wheel, depending upon the particular type of wheel guarding required by the work being handled.

In Figures 3 and 4 the guard of Figures 1 and 2 is shown in place on the machine, in proper guarding relationship to the wheel. The guard comprises a guard portion I20 of generally semicylindrical form, having a front flange, and an ear I29 which freely fits over pin I24 and is adapted to be locked in place by a wing screw I3I Referring to Figure 2, the parts are so adjusted as to dispose guard I28 in comparatively close guarding relationship with wheel I1 and this relationship is also illustrated in Figure 13. In Figures 14 and 16, the guard has been removed and reversed end for-end and reinstalled, with the flange on the inside of the wheel, to make room for the tool in the particular grinding operation illustrated, it being understood that while lateral guarding of the wheel is no longer present, the cylindrical portion of the guard is still effective to guard the operator.

In Figures 5 and 6, the guard foundation assembly is illustrated having a modified guard I33 installed thereon. A lug I34 on the guard fits over pin I24 and is locked in place by a wing screw I35, it being observed that nut I20 has been loosened and link I23 rocked upwardly into the position shown, to compensate for the increased diameter of the wheel and guard. The parts are then locked in place to securely hold the guard in operative position with respect to the wheel. Referring to Figure 17, guard I33 is shown in proper guarding relationship to a dished form of wheel Ila, it being observed that the guard fits down closely around the wheel and that the front flange adequately guards the operator.

While any number of different size and type of guards may be provided for interchangeable installation on pin I24, the two guards shown have been found to take care of the various sizes and types of wheels generally used, and by reason of the ready adjustability of the guard toward and away from the wheel to meet various grinding conditions, the reversibility of the guards and also the adjustability of the supporting arm, the wheel may be efficiently guarded for all grinding operations.

The invention also embodies a novel work stop device adapted to cooperate with the teeth or other projections on the work and maintain it in fixed angular relationship to the grinding wheel during the grinding operation, and yet permits ready indexing.

Referring particularly to Figures 11, 11a. and 12, the device comprises a base member I-4I, having a longitudinal slot I42 and terminating at one end in a head I43 having a pair of intersecting openings I44 and I45 which preferably are of the same diameter. A set screw I46 threaded into the head is adapted to lock a member placed in either aperture.

The base member is adapted to be secured in place on various parts of the machine by means of a T-bolt I41 and a nut I48. For instance in Figure 2 the'base is secured to the face of the auxiliary table by means of the bolt I41 seating in the T-slot 32, while in Figure 13 the base member is secured to ear I I1 of foundation memher I I4, so that the work is movable with respect to it.

Referring again toFigure 11, cooperating with head I43 of the base is a rod I49 having an enlarged end providing a. transverse opening II. Rod I49 may be mounted directly in opening I44 or I45 and locked in place by set screw I46. However, in handling certain classes of tool and cutter grinding, it is desirable to offset the rod from the base and we have accordingly also provided a pin I52 having a head providing across bore I53 of sufiicient size to receive rod I45, and a tlireaded lower end I54. Rod I49 is adapted to be installed in bore I53 and pulled down into engagement with V-notches I55 in a collar I56 by means of a nut I51 threaded on the reduced portion I54 of pin I52, it being observed that the shank of the pin is of substantially the same diameter as openings I44 and I45, whereby it may be installed in either opening. In this instance, however, it is unnecessary to lock pin I52 in place with setscrew I46, as the frictional force set up by nut I51 is usually suiiicient to frictionally lock the parts.v

Adapted to be inserted in opening I 5| of rod I49, and locked in place by means of a set screw I58, is a rod I59 having a cross bore I6I. Re-' ferring more particularly to Figure 12, rod I59 is adapted to snugly receive a thimble or sleeve I62 having a flange I63 into which ascrew I64 is threaded. Mounted for sliding movement in sleeve I62 is the threaded shank I65 of a stop finger supporting head I66, the shank having a longitudinal groove or keyway I61 cooperating with a reduced end I66 of screw I64 to restrain it against rotation within the thimble. Threaded onto the shank is a nut 69, which bears against the upper face of fian e I63 and is adapted to thread the shank upwardly in the thimble, the

shank being shown in its lowermost position in Figure 12.

Head I66 is provided with a recess "I and pivoted therein on a pin I12 is a finger supporting member I13. The finger support is urged in a clockwise direction by a spring I14, seating in recesses in the member and head I66, toward an adjustable stop screw I15 threaded into the head. Member I13 is also adapted to be locked against rocking movement by means of a set screw I 11 threaded intohead I66 and cooperating with a depression I18 in member I13.

Member I 13 is adapted to interchangeably support either the straight finger I19 shown in Figure 11, or the hooked finger I8I shown in Figure 11a, the fingers being secured in place by a screw I82 threaded into the end of member I13.

Taking up the grinding operations illustrated in the several perspective views, we have shown in each instance a spacer block I96 interposed between the head and tailstock and the auxiliary table. Each block is provided with a rib on its lower face adapted to seat in the T-slot of the auxiliary table and has a longitudinal slot in its upper face adapted to receive the head and tailstock keys. In this instance pressure members 81 and 81c are mounted directly on the spacer blocks. While it is to be understood that blocks I96 need only be employed when large diametered work is being handled, they may, if desired, be left in place as permanent parts of the machine.

Referring first to Figure 2, the machine is illustrated as having a simple hand reamer I9I mounted in place between centers 95 and I69; the auxiltool edges to be ground exactly parallel to the path of travel of the main table; and the straight finger stop I19 is shown as cooperating with the teeth of the reamer for stepping it around as the grinding operation proceeds. Stops. 26 are so adiusted on rod 21 as to cause stop pin 26 to limit the travel of table 23 to that required to grind the tool. The head and tailstock and spacer block assemblies are secured to the table by bolts somewhat longer than those shown in Figures 8 and9.

In this instance base member I is clamped directly to the top of the auxiliary table by bolt I41 and rod I59 is clamped directly in opening I45 by means of set screw I46. The stop assembly is directly carried by rod I59 and is so oriented as to be stopped by screw I15 when the finger pivots toward the front of the machine, with the result that the operato with each passage of the work need only rotate the reamer an angular distance corresponding to one tooth space, and during this "indexing operation the reamer will pivot the finger outwardly against the action of spring I14 into the proper position to stop the next tooth or cutting edge in the proper grinding position. It is to be understood that, if the work is not properly ground by single passage across the wheel face, handwheel 2| may be rotated to move slide table I9: work table 23; and auxiliary table B'bodily toward the grinding wheel by the necessary distance to take off the-required amount of metal to restore the cuttin edges of the tool. It is to be understood that during grinding the operator will grasp the work and urge it into firm contact with the stop.

- As is well understood in the grinding art, it is often desirable to cut with only a portion of the wheel face, the grinding face often being tilted from one-half to one degree from the plane of the surface being ground, which prevents the back edge from dragging; eliminates any possibility of burning, and results in a much better job. In the present machine this cooking or tilting of the wheel is eifected by loosening the bolt for the column and turning the column through the required angle (usually from onehalf to one degree) to incline the wheel face at a similar angle with respect to the path of travel of the main table.

It should be observed that in this particular setup of the tooth stop, neither rod I49 norpin I52 and itsassociated parts is employed. The number of parts employed in any case will depend upon the conditions of each setup. and

and peripheral cutting edges I and 45 bevel corners I96, the parts being shown in Figures 15 and 16 in proper position to grind the 45 corners and in Figures 1 and 14 in position to grind the peripheral edges I95.

Referring first to Figures 1 and 14, the auxiliary table is set on zero, to that it will move parallel to the plane of the wheel. Guard I26 has been removed and replaced in reversed position on shaft I24, and spacer blocks I 96 are again used to raise the head and tailstock the proper distance to provide the required swing of the tool.

Base member I of the finger stop assembly is secured directly uponthe auxiliary table by means of bolt I41 and nut I48 and in this instance rod I59 is mounted directly in opening I45 of the base and locked therein by screw I46. Rod I59 carries thimble I52 of the stop assembly, and in this instance the hook form of stop IN is secured to carrier I13 in an inclined position, so as to lie directly under the tooth being ground. The head IE is so disposed that arm I13 is freely pivotal toward the wheel, so that upon completion of the grinding of one face the tool may be rotated clockwise (Figure 14) to bring the next face into grinding position, it being understood that in all of the grinding operations, the operator will exert sufiicient pressure upon the tool beyond the tooth stop then re-engaging the stop to maintain the stopped tooth in firm engagement with the tooth stop, thereby predetermining the amount of metal the wheel will remove from each tooth.

When all of the peripheral edges I95 have been sharpened in the manner Just discussed, the parts are then brought into the relationship shown in Figures 15 and 16, as follows; The tool and mandrel are removed from the centers and reversed end-for-end, so as to incline the teeth upwardly adjacent the wheel; nuts 59 are loosened and the table rocked 45, as determined by the graduations on scale plate I5. It is also desirable to recombine the parts of the tooth lock device as follows. As seen in Figures 15 and 16, base MI is clamped to the auxiliary table in reversed position from Figure 14, and pin I52 is inserted in opening I45 in the base and rigidly clamps rod I53 by means of collar I56 and nut I51. Hook finger I8I is inclined as before, but in this instance engages the top of the teeth as they are successively brought into grinding position and it is accordingly necessary for the operator to exert a clockwise rotative force upon the tool during the grinding operation.

When it is desired to grind the tapered corner I96 on the other side of the cutter, it is merely necessary to rock the auxiliary table to its opposite 45 limiting position and to move the tooth stop finger assembly onto the other side of the tool.

In Figure 13 there is shown a helical cutting tool I carried by a mandrel 202 between the centers inoperative grinding relationship with wheel II. In this setup of parts the auxiliary table is again set on zero, so as to travel exactly parallel with the cutting face of the wheel, but as the teeth'203 of the cutter are of helical form and must be rocked during grinding, a somewhat different stop arrangement is employed.

Base member MI is clamped to the underside of lug II! of the guard foundation by means of bolt I41 and nut I48, so as to maintain the stop assembly stationary while the work is being moved across the wheel face. Pin I52 is secured in vertical opening I44 in base MI and is secured therein by nut I51. Rod I59 is located in opening I53 of pin I52 and clamped against collar I55. Carried in opening IGI of rod I59 is a special form of tooth stop which consists of a plain rod 204 held in position by set screw I60 and engages between the teeth of the cutter in such manner that when the auxiliary table is moved past the wheel the cutter will be rocked about the centers the necessary amount to maintain the surface to be ground in the proper relationship to the cutting'face of the wheel, it being understood that the operator will, as before, exert with the next tooth to be ground.

In Figure 17 there is disclosed a forming tool 205 carried by a mandrel 208 between the centers of the headstock and tailstock, and is adapted to be ground by a dish form of wheel I'm. In this instance the auxiliary table is again set on zero so as to carry the work in a path at right angles to the wheel axis and a re-arrangement of the parts of the stop mechanism is also utilized. The tool is provided with inclined tooth faces 201, and in order to grind them properly a dish wheel is employed.

Referring to the tooth rest or stop mechanism, base MI is secured directly to the face of the auxiliary table by bolt I41 and nut I48, and carried by pin I52, inserted through opening I45 in the base, is rod I49. The latter in turn supports rod I59 to which the stop thimble I52 is secured. In this instance the straight stop finger I79 of Figure 11 is secured in place by screw I82 and engages directly behind the tooth being sharpened, head I66 being so oriented that the finger will freely pivot upwardly and allow a new tooth to be presented to the grinding wheel in response to indexing movement of the tool.

In Figures 18 and 19 we have illustrated a modified form of head and tailstock also forming part of the invention. Referring first to Figure 18, the.

base is of substantially the same form and is secured to the auxiliary table in a manner similar to the tailstock previously described. As seen in Figure 18, the headstock 2I2 is symmetrical in form, having an enlarged head portion 2I3 provided with a longitudinal bore 2I4 communicating with an opening 2I5. At each end of portion 2I3 is provided an ear 2I6, and each ear is split in a vertical plane by a milling cutter, the bottom of the cuts being indicated by the line 2". The

- ears are provided with screws 2I8 for tightening Ill) the split portions and locking the center H9 in adjusted axial position therein. In this instance the center is shown as made up of a major portion 2I9 of relatively inexpensive and noncritical material and a hardened alloy insert 22I, which forms the actual center.

Referring to Figure 19, the tailstock 223 is made from identically the same pattern and is basically the same in all respects, having an enlarged portion 224, a central bore 225 communicating with an opening 226, and at each end is formed an ear 227, the ears being split by a milling operation along the lines 228. In this instance however center 229 is provided with a longitudinal groove 230 cooperating with a washer 23I to prevent rotation of the center and yet permit free endwise movement. 7

Center 229 is adapted to be locked in adjusted position by a cap screw 232 threaded into one ear 221, washer 23I being sufficiently thin as to not interfere with the clamping action. Center 229 is urged toward work gripping position by a compression spring 233 reacting against a cap 234 securely clamped in the tailstock by a screw 235 cooperating with the other pair of ears 221. The center is adapted to be retracted by a rod 236 projecting through cap 234 and threaded into the center. Cooperating with a lock nut and washer assembly 231 on the free end of rod 236 is the forked end 238 of a lever 239 which is pivoted on a pin 24I carried by a pair of supports 242 formed on cap 234.

In the fully released position shown in Figure 19 the forked end of lever 239 lies against the rear face of cap 23!, and, when it is desired to retract the center, a handle 243, secured to lever 239 is rocked downwardly, which causes the forked end to move the center to the right, against the action of spring 233.

In Figures 20 and 21 we have illustrated a fin adjustment applied to the auxiliary table, which makes it possible to accurately adjust the table to bring the tool into correct alignment with the wheel even when extremely small angles are involved, without resort to tapping or other expedients.

Provided on the interior of the side webs of the auxiliary table both front and rear are bosses 25l and 252 into which are threaded a pair of adjusting

screws

253 and 254 respectively, which may be manually manipulated by cross pin handles or the like. The screws preferably lie in a common horizontal plane closely adjacent the level of the top of main table 23, and cooperate with a stop 255 pivoted on a pin 255 carried by a slide member 251. The latter fits into keyway 25 and has shoulders 258 adapted to be forced into tight engagement with the undersi'des of the over-hanging portion of the keyway by a set screw 259 threaded into the slide and bearing against the bottom of the keyway. Stop 255 may be pivoted clockwise out of the path of

screws

253 and 254 when it is desired to adjust the machine without them, or when the table is adjusted through angles which are too large to permit use of the adjusting screws.

Accordingly, when it is desired to employ the fine adjustment, as for instance when grinding tapered reamers or other tools which may not be true, stop 255 is swung into its full line position; the table is adjusted into the approximate position desired; and the table T-bolt nuts 52 tightened sufliciently to exert a frictional drag.

Screw

253 or 254, depending upon the direction the table must be rocked, is'then screwed in. This causes the selected' screw to engage the stop and force the table to turn about its axis against the resistance of the frictional drag. When the adjustmentis complete, nuts 59 are tightened to rigidly lock the auxiliary table in place. In the drawings both screws have, for convenience, been shown engaged with the stop, understood that in practice only one screw will be engaged, the other being backed oil to allow the tableto turn. It is also to be understood that while we prefer to employ a single stop, in combination with front and rear screws, if desired, both screws may be mounted at the front of the table on opposite sides of the pivot and cooperate with separate stops at opposite ends of the table, without departing from the spirit of the invention.

In addition to permitting fine adjustments to be carried out, the novel screw and stop assembly is also advantageous in many other classes of grinding as it makes it possible to set up the parts with the surface to be ground parallel to the travel of the main table, irrespective of shape.

From the foregoing detailed disclosure it is apparent that the invention provides a novel auxiliary table which may be readily installed on the tables of present day surface grinders, for the purpose of converting them to tool and cutter grinders, and which may be adjusted about an axis normal to the table surface to locate the tool or cutter at the proper grinding angle, and also provides novel head and tailstock but it is to be ous grinding l4 assemblies; a tooth rest or stop of novel construction; and guard and guard supporting assemblies which are so designed as to permit a number of diiIerent guards to be interchangeably mounted on the support and affords adjustment of the guards into various guarding positions with respect to the wheel, to permit varioperations to be carried out without from the guards, and at the same maximum protection to the operainterference time affords tor.-

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention. being indicated by the appended claims rather than by the foregoing description, and, all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

1. In a machine tool having a grinding wheel, a slide table and a horizontally reciprocal, work table providing a horizontal, planar work supporting surface below the grinding wheel, an attachment comprising a pilot member; means for securing said pilot member to said work support ing surface; an auxiliary work supporting table overlying said pilot member and resting on said work supporting surface in vertically spaced relationship to said pilot member;- pivot means mounting said auxiliary work supporting table for rocking movement about a vertical axis on said pilot member; means on said pivot means for drawing said auxiliary work supporting table down into clamping engagement with said work supporting surface; and means on said auxiliary work supporting table for holding a work piece thereon in position for presentation to said grinding wheel.

2. The combination defined in claim 1 wherein said auxiliary work supporting table is provided with a fiat upper face disposed parallel to said work supporting surface and on its underside is provided with at least two transverse ribs, one located each side of said pivot means, said ribs having lower faces located in a common plane and adapted to clampingly engage said work supporting surface in any one of a plurality of adjusted angular positions about said vertical axis.

3. In a grinder having a flat, T-slotted work supporting table, a tool holder comprising a pilot member of disc-like form provided at diametrically opposite points with a pair of securing devices coacting. with the T-slot of said work'supporting table and operable to secure it in frictional clamping engagement therewith; means, located adjacent each of said securing devices, and projecting into the slot of said work supporting' table, for accurately keying said pilot member thereto; an auxiliary work supporting table member overlying said first mentioned work supporting table and having a downwardly projecting portion located either-side of said pilot member and resting on said first mentioned work supporting table; a pivot pin, rigidly secured in an opening in one of said members and snugly journalled in an opening in the other member, mounting said auxiliary work supporting table member for limited rocking movement; and clamp means cooperating with said pilot member and said auxiliary work supporting table member