US1821169A - Abrasive testing machine - Google Patents

Description

Sept. 1, 1931. H. H. LA VERCOMBE 1,321,159

' ABRASIVE' TESTING MACHINE I;

Filed Aug. 28, 1925 4 Sheets-Sheet 1 ymwmze Sept. 1, 1931. H. H. LA VERCOMBE 3 3 ABRASIVE TESTING MACHINE Filed Aug. 28, 1925 4 Sheets-Sheet 2 abtorwuja.

Sept. 1, 1931. H. H. LA VERCOMBE ABRASIVE TESTING MACHINE 4 Sheets-Sheet 5 Filed Aug. 28, 1925 gnuento'a:

P 1931- I H. H. LA VERCOMBE ,821,169

ABRASIVE TESTING MACHINE Filed Aug. 28, 1925 4 Sheets-Sheet 4 iiilm 55 I Q) 5/ mnmuunnum 5% 5o 3 nuanf 01 II IIHIIHW Patented Sept. 1, 1931 UNITED STATES PATENT OFFICE HARLEY H. LA VERCOMBE, OF DETROTT, MICHIGAN, ASSIGNOR TO ABRASIVE ENGI- NEERIN G CORPORATION, OF DETROIT, MICHIGAN, A CORPORATION OF MICHIGAN ABRASIVE TESTING MACHINE- Application filed August 28, 1925. Serial No. 52,974.

This invention relates to machines for testing grinding wheels to secure definite data as to their wearing and abrasive qualities so that their adaptability to different classes of work may be properly ascertained.

These qualities are not necessarily dependent upon the size, nature or sharpness of the abrasive material itself, but are usually dependent to a'considerable extent upon the manner in which the grains of such material are supported, it being understood that the matrix or binder by which the said grains are held together may vary considerably and thus alter or influence the cutting qualities of the abrasive material itself, as Well as the ability of the material to withstand wear.

Devices have been suggested from time to time in the form of machines adapted to subject a test piece of steel, or other material, to the action of a stone so that the effect of the stone on the material and the effect of the material on the stone may be observed, and a grading of the stone as to its abrasive and Wearing qualities arrived at.

For example, the machines described in United States Letters Patents granted to me, Nos. 1,435,314, dated November 14:, 1922, and 1,446,977, dated February 27, 1923, are of this type.

The present invention has for its object to effect still further improvements over the machines hitherto known, whereby the grad ing of grinding wheels according to abrasive andwearing qualities may be much more closely determined.

To this end the said invention further aims in such a machine to ensure a constant peripheral speed of the grinding surface irrespective of the circumference of the grinding wheel being testedand the wear of the stone or ofthe test piece, wherefore provision is made for the rotating of a stone at a speed inversely proportional to its diameter.

The invention has as a further object to provide .for the determining of uniformity of wearing quality in a wheel whereby uneven wear thereof may be readily detected, and the extent of such uneven wear ascertained; still further objects being to provide for variation of the pressure of the test piece on the grinding wheel, as well as providing a method of applying pressure to the test piece without materially increasing'the load on the bearings in which the spindle carrying the test piece is mounted.

Still further objects subsidiary to or resulting from the aforesaid objects, or from the construction or operation of the invention as it may be carried into effect, will become apparent as the said invention is hereinafter further disclosed.

In carrying the invention into effect I may provide a testing machine with a horizontally mounted and vertically adjustable grinding wheel arbor adapted for thereception of a wheel to be tested, and a vertical rotary spindle positioned and adapted to support a test piece such as of steel in contact with the top. of a wheel mounted on said arbor, said spindle being vertically movable and weighted so that the test piece will rest on the periphery of the said grinding wheel with a definite pressure, driving means effecting the rotation of said spindle and, through suitable gearing, the rotation of a friction pinion vertically movable over the face of a friction disk carried by said grindingwheel arbor, whereby, upon the raising of said arbor to bring a grinding wheel into contact with the test piece, said pinion approaches the axis of said disk to an extent governed by the diameter of the wheel; and the speed of the arbor is accordingly inversely proportional to such diameter. Means are provided for determining the number of revolutions made by said pinion or said spindle and for throwing the machine out of operation upon a predetermined number of revolutions being attained.

All of which is more particularly described and ascertained hereinafter, by way of example, having reference to the accompanying drawings, wherein Figure 1 is a perspective view of an abrasive testing machine embodying my improvements;

Figure 2 is a side elevation of the same, partly in section and partly broken away;

Figure 3 is a fragmentary sectional detail view taken on the line 300-300, Figure 2;

Figure 4 is a plan of the upper portion of the machine, and

Figure is a plan view of the machine with the upper cover plate removed.

Similar characters of reference indicate similar parts in the several figures of the drawings, and Figure 1 is drawn to a smaller scale than the remaining figures.

The body structure or pedestal 1 of'the machine illustrated is shown as having mounted thereon an upper structure 2 in which the driving and gear mechanism is arranged, and on the said pedestal 1 is a vertically slidable bearing member 3 which is adjustable in its vertical movement by means of a hand wheel 4 threaded onto a fixed feedscrew 5 which extends upwardly from the base of the pedestal through a boss 6 on the lower part of the said slidable bearing member 3. In this hearing member or slide is mounted a horizontal grinding wheel arbor 7 adapted to receive a grinding wheel 8 which may be secured thereon in any convenient manner such as by the usual plate 9, collar 10 and securing nut 11. On the opposite end of the said arbor is a friction disk 12 of substantial diameter.

The said upper structure 2 is shown as being in the form of a gear housing and also forms the housing for atest cup spindle 13, the upper end of the said structure 2 being closed by a cover plate 14 which supports a jack shaft 15 upon which is mounted a driving pulley 16 and a jack shaft pulley 17 which, through a belt 18, drives a countershaft pulley 19 mounted on a spindle 20 extending outwardly of the spindle housing.

The said spindle 13 is vertically slidable in and rotatable with a sleeve 21 which is provided with an operating pulley 22 over which a belt 23 extends guided by idler pulleys 24 and 25, and on the lower end of the said sleeve 2]. is mounted a worm 26 which meshes with a worm wheel 27 mounted on a shaft 28 extending transversely of the gear housing. This shaft also carries a sprocket wheel 29 which, through the me dium of a chain 30 and sprocket wheel 31, effects the rotation of a further shaft 32 mounted in the said housing and the conse quent rotation of a bevel gear 33 also mounted on the said shaft 32.

The gear 33 is housed in the upper end of a hollow arm 34 swingablymounted on the said shaft 32, which extends outwardly of the structure 2 for that purpose, and 35 is a rotary spindle journaled in the said arm and provided at its upper end with a bevel gear 36ineshing with'the aforesaid bevel gear 33, and at its lower end with a friction wheel 37 which engages the face of the friction disk 12 under the influence of a weight 38 which exerts pressure of the friction wheel 37 against the disk 12.

It will be apparent that in this way the grinding wheel arbor 7 is rotated at the same time as the test cup spindle 13, provided that the friction wheel 37 and disk 12 are in contact, although the arm 34 may be swung outwardly of the said disk 12 against the resistance of a spring 39 situated between the gear housing and a stop 40 carried by a projection 41 on the upper part of the arm. The stop 40 may be adjustable, as by being in the form of a nut mounted upon a threaded rod 42, so that the pressure of the spring may be varied. This arrangement permits of adjustment of the pressure of the wheel 37 against the disk 12.

The testing of grindstones with this device is effected by bringing into contact with the periphery of the grinding wheel a test piece of steel or other suitable material which I prefer to provide in the form of an inverted test cup, such as 43, secured on the lower end of the test cup spindle 13 by a nut 44, this cup being rotated in contact with the peripheryof the wheel when the machine is in operation and the grinding wheel rotated at the same time by the friction wheel 37 and the disk 12.

Upon the mounting of the grinding wheel to betested on the arbor, the slide 3 is then raised by the operation of the hand wheel 4 until the periphery of the wheel engages the test piece and raises the same together with the spindle 13 to a suflicient extent to ensure a full pressure of the test piece upon the grinding wheel, this pressure being determined by the application of weights 45 to a member 46 preferably pointed at 47 at its lower end which rests upon the upper end of the spindle 13. The member 46 is threaded at 460 for adjustment in a supporting member 48 extending above the said test cup spindle.

When the grindstone is raised into contact with the test cup the disk 12 is also raised as will be obvious, and it will be read ily understood that the smaller the diameter of the grindstone, the higher it is neces sary to lift the disk 12, and the closer the friction wheel 37 approaches the axis of the i said disk. Therefore, the smaller the diam eter of the grinding wheel the faster it will be rotated, so that the peripheral speed of the grinding wheel will be practically the same. irrespective of its size. This enables grinding wheels of different sizes to be tested to all intents and purposes under precisely the same cutting conditions, and two grinding wheels of equal abrasive quality should therefore effect an equal wear of the test cup in a test carried over equal periods of operation of the machine, irrespective of substantial differences in the diameter of the grindstones.

In orderto make proper comparisons of the abrasive qualities of grinding wheels and to .ascertain definitely the amountofmaterial ground from the test cup for a given number of feet of grinding surface applied to the test cup, indicating and timing means through the gear housing, and an arm swingably mounted on the said housing at 51 and provided at its outer end with a pawl 52 engaging peripheral teeth of a dial plate 53 so that upon each revolution of the worm wheel 27 the cam will actuate the said pawl 52 against the yielding resistance of a pawl spring 54 and effect partial rotation of the said dial plate to the extent of the pitch of its peripheral teeth. The dial plate is provided on its inner side with a pin or projection 55, and 56 is a dial pointer indicating the position of the said pin relative to trip member 57 hingedly carried by the end of the downwardly depending arm 58 of a bell crank lever which is fulcrumed at 59 to the cover plate of the gear housing. The upper arm 60 of the bell crank lever is forked and engages the underside of a collar or annular projection 61 on the test cup I spindle.

The trip member 57 rests upon a stop 62 and is provided with a shoulder 63 with which the said stop engages, 64 being a spring tending to effect the movement of the arm 58 of the bell crank lever away from the dial plate and to thereby effect the raising of the upper member 60 of the a bell crank lever, this tendency of the spring 64 being rest-rained during the operation of the machine by the engagement of the said stop 62 with the shoulder 63 of the trip member.

The object of the projection 55 on the dial m plate is to effect the release of the said trip member fromthe stop when the pro ection,

as a result of the rotation of the dial plate by the pawl 52, engages beneath the outer end of the said trip member and lifts it,

and the dial plate is provided with a knob 65 by means of which it may be manually rotated to set the projection 55 in such position that it will release the trip member 57 from its stop 62 upon the cam having made a predetermined number of revolutions.

' The said dial plate is preferably indexed as at 66 so that the pointer 56 will show the number of revolutions required to effect the disengagement of the trip member 57, which disengagement is accompanied by the lifting of the test cup spindle due to the upward size of the wheels,

swinging of the arm 60 of the bell crank lever under the influence of the springtla, whereupon the test cup 43 is lifted out of contact with the gllldlllg wheel.

In testing a grinding wheel it is placed upon the arbor and the arbor adjusted to the test cup in the manner hereinbefore described, the trip member 57 being lirst en gaged with the stop 62 for which purpose ahandle 67 is provided, and the machine is set in operation after the dial plate has been set to provide for the number of revolutions of the spindle required. The operation of the machine then continues until such number of revolutions of the spindle has been effected. the revolutions of the grinding wheel being governed by the size of the wneel as has also been described; and when the pin 55 trips the trip lever 57, the test cup 1 .3 is lifted out of contact with the grinding wheel by the action of the spring 64.

The test cup is then measured to ascertain to what extentit has been abraded by the grinding wheel, and the grinding wheel is also measured to ascertain to what extent it has been worn. and as a definite number of surface feet of the grindstone have been brought into abrading contact with the testcup, the wear of the test cup will definitely indicate the abrading quality of the grinding wheel, and the wear of thegrinding wheel will indicate its wearing quality.

If another grindstone be then substituted for that previously tested and the (.ial plate set to the previous setting, upon the completion of a further test, the same amount of wear on the test cup is an indication that thesecond grinding wheel is of the same abrading quality as the previously'tested wheel, irrespective of any difference in the and of course the wearing qualities of the wheels may be likewise compared.

It will also be apparent that uneven wear of the grindstone will manifest itself in a noticeable rising and falling of the test cup spindle, and after the test it is quite easy to adjust the. stone so that its lowspot is directly beneath the cup and then measure the extent to which the spindle'is raised when the high spot of the wheel is brought beneath the cup. This will show the uneven shape or eccentricity of the stone.

The cup shaped test piece is preferably so disposed towards the abrasive wheel that its rim lies in a plane tangential to the peripheral face of the said 'wheel. Consequently wearing; of the test piece by the abrasive wheel does not alter the diameter of the test piece of the relative velocities of the meetin faces of the wheel and the 1 l l) test piece.

Accordingly it is a very simple matter with a machine of this type to test large numbers of wheels and classify them as to their abrading and wearing qualities, without especial calculation for did erent sizes of wheels, and by actual test the results attained by a machine constructed as herein described and shown are very reliable and the grading of stones can be done much more accurately than has been possible by the methods heretofore generally adopted for that purpose.

This invention may be developed within the scope of the following claims without departing from the essential features of the said invention, and it is desired that the specification and drawings be read as merely illustrative and not in a limiting sense, except as necessitated by the prior art.

What I claim is 1. In a machine for testing abrasive wheels, means for rotatably supporting an abrasive wheel, means for supporting a test piece in contact with the periphery of said wheel, and a variable speed driving mechanism through which the wheel supporting means is rotated, means for adjusting said mechanism according to the distance of said test piece from the center of said wheel, whereby said supporting means is rotated at speeds varying inversely as the diameter of the wheel.

2. In a device of the class described, an arbor for the support of an abrasive wheel, means for supporting a test piece in contact with the periphery of said wheel, means adjustably varying the distance between the test piece support and the arbor to suit different sizes of Wheels, and a variable speed device driving said arbor, and means .for adjusting said device to maintain constant the linear velocity of the periphery of said wheel.

3. A device according to claim 2 wherein the arbor is movable towards the test piece support, and the variable speed mechanism comprises a disk mounted on said arbor and a friction driving pinion towards which the center of said disk moves as said arbor is moved towards said test piece support.

4. In a machine for testing abrasive wheels, means for rotating an abrasive wheel in peripheral contact with a test piece and means controlled by the bodily movement of the abrasive wheel relative to the test piece and ensuring a constant peripheral grinding speed of the wheel irrespective of its diameter.

5. In a machine for testing abrasive wheels, means for ,rotatably supporting an abrasive wheel, means for rotating said abra sive wheel, means for supporting a test piece in contact with the periphery of said wheel, means for maintaining constant the linear velocity of the periphery of said wheel, means for moving said test piece to an inoperative position, and timing means in suring the actuation of said moving means upon the completion of a predetermined duration of operation of said device.

In testimony whereof I afiix my signature.

HARLEY H. LA VERCOMBE.

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