US1758649A - Grinding machine - Google Patents

Description

y 1930. w. H. VCHAPMAN 1,758,649

GRINDING MACHINE Filed Jan. 10, 1927 3 Sheets-Sheet 1 2o 40 24 l 1 38 l l 1 May 13, 1930. w. H. CHAPMAN GRINDING MACHINE Filed Jan. 10, 1927 3 Sheets-Sheet 2 llilrmltill ll /N\/ENTOQ- WILL/AM H. CHAPMAN,

HIS ATTOQNEV.

May 13, 1930. w. H. CHAPMAN GRINDING MACHINE Filed Jan. 10, 1927 3 Sheets-Sheet 5 Patented May 13, 1939 NE'IE STAT T :0 F FI CE \VILLIAM -I-I. CHAPMAN, 0F IMQN'J'.CLAIR, NEW JERSEY, ASSIGNO'R TO GENERAL MOTORS CORPORATION, OF ZDETROIT, "MICHIGAN, A CORPORATION OF DELAWARE GRINDING BEACH-ENE Application filed January 10, 1927. Serial No. 1G0,068.'

placed in a V-block and rotated under an indicator so that contact is at points 120:apart,

three high spots will be noted. There is r no satisfactory theory to account for this. Possibly initial irregularities in the workengage with the guide or the wheels in a manner to deflect the work from a normal central position, thus resulting in slip and the grinding of flats which remain equally Spaced. Grinding of the work above or below a normal position in the grinding throat between the wheels introduces conditions hard to control or correct for and results in inaccurate sizing.

An object of the inventionis to provide, for centerless grinders, an improved form of work guide which will insure the production of perfectly round work andavoid the above and other defects of prior machines. Another object is 'to provide improved mechanism for locating and holding work-pieces in a definite and established axis or path of travel between the wheels to the end that accurate sizing of the work is promoted.

To these ends and also to improve generally upon devices of the character indicated the invention consists in the various matter's hereinafter described and claimed.

The invention, in its broader aspects, is not necessarily limited to tlieiparticular embodiment selected for illustration in the Iancompan-ying drawings in which Figure 1 is a'plan view and Figure 2 is a front elevation of portions of a .centerless grinder with a centering andlocating device inoperative position.

. Figure 3 is aside elevation partly in .section of the work guidesand assoeiated medl i A nu anism.

of which is adjustable endwise.

Figures land 5 are detail sectional views f the work guides.

Figures 6 and 7 are perspective views of certain work guides.

F igures S, 9, 10, and 11 are diagrammatic views indicating the relation of the work and its guides to the wheels, Figure 11 being a modification.

The numeral 6 indicates a grinding w h'eel rotatable at high-speed withits shaft 8, and 10 indic'a'tesa slower regulating wheel whose axis or shaft 12 is tiltable in-a plane parallel to a work :guide extending between the wheels. The grinding wheel moves downwardly at the work, the regulating wheel moves upwardly at the work, and the work guide is adjustable to locate and support 'work-pieces for lravel through the machine with the axes of the work-pieces always in a b definite .locatiompreferably at'the point of nearest approach of the wheels. Any suitably known form of control mechanism :may be provided to cause the wheels to feed towards or from one another and the interposed work. The wheel shafts and their mountings are arranged to extend away from each other and from the wheels on the opposite sides of the guide to neutralize the tendency for deflection :of the shafts during grinding to thus maintain the acting parts of the wheel 0 tering device is provided. This comprises a centering rod 16 haviiigrend openings to be engaged by aligned xtape'r centers 18 one The taper centers 1:8 are carried "by swingable arms 20,

reachpivoted at 225011 a-standard 24 andeach "having at one end a screw 26 arranged to engage either in a tapped opening 28 in .an opposite, companion standardmrin ia tapped opening 3.0 inthe same (standard. Figure 1 shows rod in cente i g position with, a

' operated at a common source.

dummy or reference work-piece D sleeved upon it, the piece being previously accurately sized externally and accurately fitting the rod internally for the purpose of locating, with reference to it, the work guides and the wheels for producing finished work of the same external size. This reference axis is preferably arranged to pass through the grinding throat at the point of nearest approach of the wheels. By the use of difierent sized dummy work pieces, all sizes of work can be ground by the wheels at the same level so no inaccuracies will result from a variation in the sizing recess between the wheels. After locating the wheels and work guide by moving them into contact with the reference work-piece, the centering rod is removed and its supporting arms swung to vertical inoperative position.

The machine has a lower supporting bar or guide'32 and a parallel upper supporting bar or guide 34, each bar being secured at its ends to a slide block 36. Each block is grooved to slide vertically in the standards 24 and its ends are split as at 38 to enable it to be clamped in adjusted positions on the standards by bolts 40. The blocks and bars are simultaneously movable towards or from each other in equal degreeby gearing Swivelled to the lower blocks are screws 42 freely guided through openings in the bases of the standards but supported and fed endwise by worm wheels 44 connected for simultaneous rota- 1 tion by a shaft 46. The upper slide blocks are suspended by rotatable screws 48 guided loosely through cross bars 50 connecting the standards, the screws being supported and fed endwise by worm wheels52 which are connected for simultaneous rotation by a shaft 54. The worm wheels 44 and 52 at the front are driven by worms 56 and 58, respectively, and the worm shafts are connected by sprocket wheels 60 and a chain 62,

.1 the upper worm shaft being directly controlled by a hand wheel 64. Thus the guide bars move together but in opposite directions equally so that work-pieces of different diameters will be supported at the same level be- ."ftween the wheels. Individual movement, as

to provide for initial adjustment or for wear, is eifccted by lining to the screws. hand wheels 66 which enable either screw to be turned individually to feed it endwise past its worm t wheel.

-' grinding. wheel and projects beyond it to.-

wards the front or work receiving side as shown in Figures 1 and 10 so that by pressing the work towards this projecting portion of the regulating wheel, the work is started rotating before it reaches the grinding wheel and hence the grinding of flats or the mutilation of the leading end of the Work by the grinding wheel is obviated. The work may be pressed towards the regulating wheel and the lower work guide by any suitable mech anism. As shown, a blade 74 having a bevelled end 76 is slidably mounted in a recess 78 of the upper guide bar and is pressed clownwardly by a leaf spring 80 between. the top edge of the blade and the top wall of the recess. The blade is loosely confined laterally by a cover plate 82 clamped by screw bolts 84 against a shoulder or ledge 86 surrounding the blade recess, some of the bolt heads having flats so that the cover plate and blade can be removed upon a partial turn of the bolts. The downward movement of the blade under influence of the spring is limited by nuts 88 on adjustable stop screws 90 threaded in the blade and passing loosely through openings in the top of the bar.

The lower work guide which forms one of the important features of the invention comprises a plurality of blades the work engaging points of which are arranged in an are having a radius R exactly equal to the radius of a finished and accurately sized work-piece, the blades being located wholly to one side of the axis A or path of travel of the center of the work-pieces. In a recess near the center of the length of the bar 32, at a location including the peripheral width of the wheels, a blade 94 is secured by bolts passed through openings 96. The blade is let into a recess 98 of the bar and is adjustable edgewise by a screw 100 to locate its top edge 102 just beyond the top of bar 34 or flush with a wear plate 104 on the bar. The blade is located wholly at one side of the center of the bar and on the side opposite the regulating wheel. Other blades 106, 108, are spaced apartin parallel relation to one another and to the blade 94. Blades 106, 108, and 110 are adjustably mounted in grooves of end guide blocks 112 and 114 which are rigidly spaced by a back plate 116 secured to them by screws 118. The guide block 112 is secured to bar 32 by a bolt 120 passing through the block 112, through a spacing member or bushing 122 which is in a notch of blade 94, and

through the bar 32. The spacing member 122 holds the end block 112 flush with the side of the bar 32. The guide block 114 is secured directly to the side of the bar 32 by a bolt 124. The blades 106, 108 and 110 have end faces 126, 128 and 130 which are inclined and these faces may be straight or transversely curved. The blades are adjustable edgewise by adjusting screws 132, 134 and 136 engaging the bottom edges of the blades and threaded in bottom plates 138 attached to the end guide blocks by screws 1 10. Clamping screws 144, 146 and 148, threaded in the guide blocks, hold the blades in adjusted positions in their grooves.

Vhen a dummy or accurately sized reference work-piece D has been located by the centering device in the manner described, the upper and the lower bars and the wheels (then idle) are moved to work contacting position. The blades are adjusted so that they contact with different portions of the circumference of the dummy or reference work-piece, their end faces or work engaging portions 126, 128 and 130 being located in an arc of a radius R exactly equal to that of the reference workpiece. Once the blades and the regulating wheel are thus located, they are allowed to remain and, during grinding of the real work-pieces V, only the grinding wheel is fed in towards the work as the work reaches size. Meanwhile, the upper springpressed blade 74 keeps the work pressed towards the regulating wheel and the work blades. The blades being located at one side of the axis of the work, the downward pressure that the grinding wheel produces is largely exerted or transferred laterally to the regulating wheel which insures uniform rotation without the slip that may occur if the pressure is wholly or largely exerted against a work support that is continued over under the regulating wheel side of the work path. The rough work is so guided that the cutting action trues up any out of round condition and as it reaches size, it is supported in the proper final position at a number of accurately located contact points on its periphery and a true cylinder results.

If desired, the work guide may be a single wide blade 150 having a radius equal to that of an accurately sized and finished work'- piece as indicated in Figure 11. This guide also presents a plurality of work contacting portions in the finished arc and irregularities that exist in the rough work do not perpetuate themselves as they do when striking at a single point of support. The sectional type of support, however, allows grit to work out readily and is conducive to a smooth finish.

I claim:

1. In a centerless grinding machine, in combination, a grinding wheel rotatable at relatively high speed, a regulating wheel rotatable at relatively low speed, the grinding wheel moving downwardly and the regulating wheel moving upwardly with respect to an interposed work-piece, and a work guide having work engaging portions located in an arc of a radius equal to that of a finished and accurately sized work-piece, said work guide being located wholly at the side of the axis of the work-piece opposite the regulating wheel whereby the work is held from lateral displacement by a plurality of contacts with the guide without loss of rolling contact with the regulating wheel; substantially as described.

2. In a centerless grinding machine, in combination, a grinding wheel rotatable at relatively high speed, a regulating wheel rotatable at relatively low speed, the grinding wheel moving downwardly and the regulating wheel moving upwardly with respect to an interposed work-piece, a work guide having a plurality of work engaging portions located in an arc of the same radius of curvature as a finished and accurately sized workpiece and arranged to support the work-piece at the side of its axis opposite the regulating wheel, and a member for pressing the workpiece towards the work guide and towards the regulating wheel; substantially as described.

3. In a centerless grinding machine, in combination, a grinding wheel rotatable at relatively high speed, a regulating wheel rotatable at relatively low speed, the grinding wheel moving downwardly and the regulating wheel moving upwardly with respect to an interposed work-piece, and a guide for the work-piece comprising spaced blades having their end portions positioned to conform to the periphery of a finished and accurately sized work-piece: substantially as described.

4. In a centerless grinding machine, in combination, a grinding wheel rotatable at relatively high speed, a regulating wheel rotatable atrelatively low speed, the grinding wheel moving downwardly and the regulating wheel moving upwardly with respect to an interposed work-piece, and a work guide comprising a plurality of parallel blades with means for individually adjusting the blades to make their end faces contact with the periphery of a work-piece at a plurality of points; substantially as described.

In a centerless grinding machine, in combination, a grinding wheel rotatable at relatively high speed, a regulating wheel rotatable at relatively low speed, the grinding wheel moving downwardly and the regulating wheel moving upwardly with respect to an interposed work-piece, a pair of guide blocks having grooves, blades movably mounted in the grooves. means for individually moving said blades, and means for clamping said blades with their end faces in contact with a work-piece at a plurality of points; substantially as described.

6. In a grinding machine, a grinding wheel and means for rotatably supporting a workpiece in contact with said wheel, said means comprising. a plurality of parallel blades having their end faces arranged to contact with the periphery of the work-piece at a plurality of points; substantially as described.

In testimony whereof I hereunto affix my signature.

WILLIAM CHAPMAN.

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