US1534014A

US1534014A - Grading machine

Info

Publication number: US1534014A
Application number: US332518A
Authority: US
Inventors: Charles E Gillett
Original assignee: Norton Co
Current assignee: Saint Gobain Abrasives Inc
Priority date: 1919-10-22
Filing date: 1919-10-22
Publication date: 1925-04-14
Anticipated expiration: 1942-04-14

Description

April 14, 1925. 1,534,014;

/ c. E. GILLETT GRADING MACHINE Filed Oct. 22, 1919 2 Sheets-Sheet 1 W/ T/VESS INVENTOR M7?%r 4 Gan/MM 6711a? April 14, 1925. 1 1,534,014

C. E. GILLETT GRADING MACHINE Filed Oct. 22, 1919 2 Sheets-Sheet 2 INVENTOR W T/VES 5 flmisT 6/41- 577 Patented Apr. 14, 192 5.

UNITED STAT i t E. GILLETT, 0F "WORCESTER, MASSACHUSETTS, .ASSIGNOB, TO: NORTON COM- PANY, OF WORCESTER, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

GRADING MACHINE.

Application filed October 22, 1919. Serial No. 332,518.

To all whom it may concern:

Be it known that 1, CHARLES E. Gmnrr, acitizen of the United States of America, residing at Worcester, in the county of Worcester and State of Massachusetts, have invented certain new and useful Improvements in Grading Machines, of which the following is a full, clear, and exact specitalline alumina or silicon carbide granules 3 bonded by vitrified clay material, is to predetermine the cutting ability and other inding characteristics of the wheel when it is used in a grinding machine. This is usually donebyv testing a wheel which has proven satisfactory for a certain class of work with a grading machine which indicates certain characteristics under duplicate tests and comparing wheels to be graded with this standard. The :grade' of such wheels has heretofore been determined by a test of the hardness of the. clay bond and has not adettluately taken the physical char-1 acteristics o the abrasive grain into account, since a wheel made of weak, eas ly fractured abrasive grains will have a diflerent grinding ability from one made of tough abrasive grains, although the clay bonds in the two wheelsmay be alike.

One object of my invention is to provide a simple and accurate method of classifying abrasivebodies and similar articles and to utilize a machine for this purpose which may be easily used by an unskilled operator to obtain uniform results and a satisfactory classification of the body being graded relative to a standard body.

' It is a further object to utilize for classifying such articles the principles involved in relatively moving the tool and the article being graded in frictional engagement along an extensive pathand measuring and comparing the frictional forces involved.

To the accomplishment of these objects and such others as may hereinafter appear, as will be readily understood by those skilled in the art,'the invention comprises the general features and combination of parts heremafter described and more particularly pointed out in the appended claims.

The preferred embodiment of the machine for carrying my improved method of grading into practical effect is illustrated in the accompanying drawings in which Fig. 1 is a plan view of the machine, certain parts being omitted for the sake of clearness;

Fig. 2 is an elevation of the machine shown in Fig. 1; i

Fig. 3 is a plan of a modified form of the machine shown in Figs. 1 and 2;

Figci 4 is'a section on the line 44 of Fig. 3; an

Fig. 5 is a section on the line 55 of Fig.

cation of the characteristics of the wheel, I

prefer to measure also the wear on the tool under standard conditions which taken with the measure of friction enable one to duplicate wheels with a high degree of exactness and thus to accurately foretell the working ability of the wheel as is indicated by the grade mark.

In accordance with the illustrated embodiment of my invention I classify such bodies as grinding wheels by determining the variation in the force required to hold either the wheel or tool stationary while the other part is moved relatively thereto along what may be termed an extended path, which force varies in, accordance with the frictional characteristic of the wheel, the tool of course being of the same size and material and exertin the same pressure on the wheel for all whee s beingjcompared. In addition to determining the friction exerted by or upon a standard tool I also preferably measure the wear or abrasive action on the tool under standard conditions as a second indication of the cutting action of the wheel when in use. 0

Referring to Figs. 1 and 2, the wheel 10,

means of a clamping screw 17.

, rotating in the direction is mounted to turn in a suitable base 14 which also supports a movable tool-carrying arm 15 in which a tool 16. is secured by The arm 15 is weighted if necessary, as b pi oduce the desired pressure between the tool and the wheel and, in order that the tool as it is worn away may move toward the wheel, the arm 15 is mounted on a hinge member 19 pivotally mounted on the base 14 between ears 20. When the wheel is of the arrow shown in Fig. 1, the tool tends to move with the wheel and I make use of this fact to determine the cutting characteristics of the wheel which have a definite relation to the force required to restrain the tool from movement under the frictional action of the wheel when it is rotated. To this end the arm 15 is pivotally mounted on a vertical pivot 23 formed on the hinge member 19 so that it is capable of movement in a plane parallel to the plane of rotation of the wheel. This movement is restrained by a measuring instrument, such as a dynamometer, which mdicates the force acting on the arm tending to cause it to move with the wheel. A convenient form of dynamomcter is illustrated in Figs. 1 and 2, which comprises a stud 24 passing through'a clearance hole 25 in the arm 15 and provided with a head 26, which engages one end of a helical spring 27 confined between it and the arm.

In order that the angular movement of the arm 15 under the influence of the wheelmay not vary the frictional effect, I provide means for moving the arm to a radial position with respect to the Wheel inwhich position it will receive the maximum frictional effect. For this purpose an arm 28 is formed integral with the member 19 and is provided with a clearance hole for the stud 24. A

thumbnut 29 is provided on the stud so that the nut can be turned to exert a greater orless pressure on the arm 15 through the spring 27 sq as to bring the arm back to a radial position which will be indicated by the position of apointer-BO with relation to an index mark 31 on the arm 28. By this construction when the nut 29 is turned to bring the arm 15 to a radial position as indicated by the pointer, the'force exerted by the rotating wheel onthe arm will be indicated by the pointer 32 which moves over a scale 33 provided with any convenient graduation. In order that the starting friction,

or the friction of rest,'which will be greater than the corresponding force required fter the parts have assumed their normal running position, may not be recorduring its Wear.

the weight 18 suspended therefrom, to

suitable source of power,

' iaseaomr ed, I prefer to observe the point at which the pointer 32 comes to a substantially rest after the wheel has acquired its full or predetermined speed. In order to observe a further abrading characteristic of the wheel I may utilize a wearable tool and provide means for meas- For this purpose, I may provide a micrometer device indicated generally at 35, which may be conveniently mounted on anupright 36 formed integral with the base 14, so as tobe in position to receive the tool 16 when it is swung into a vertical position about the horizontal axis of the hinge member 19, as indicated in dotted lines in Fig. 2. Since the wear will vary in accordance with the duration of the test, it is essential that the test shall be conducted for a definite period of time or that other means be employed for limiting the abrasive action of the wheel. In using the machine illustrated, the time of treatment or the number of revolutions of the wheel is noted.

In the modification of the invention illustrated in Figs. 3, 4 and 5, a somewhat similar device is shown, the only essential distinction being that the grinding wheel shown in the modification remains stanow ary while the tool moves, which is a reversal of the relative movement of these parts as shown in Figs. 1 and 2. As illustrated, the wheel 37 is'non-rotatably held upon any convenient support, preferably in axial alignment with a vertical shaft 38 which is rotatably supported in the machine frame 39 and driven by the pulley 40. A radial arm 41 revolubly mounted on the lower end of the shaft and held in place by the head 42 is arranged to be turned by the shaft. This arm carries a wheel-engaging tool 43 which is vertically slidable through an aperture in the arm and is held down against the wheel 37 by a weight 44 guided in its Vertical movement by two guide rods In order that the frictional resistance of the wheel acting to retard the movement of the tool may be observed, the tool is driven through a spring which forms, in eflect, a dynamometer. One arrangement for this purpose comprises a spring 46 having one end secured to the shaft 38, as by a pin 47, and having the other end secured to the arm 41 by means of a pin 48. The arm 41 is rotatably mounted on the lower end of the shaft 38 so that when the shaft is rotated, as by means of a pulley connected to any the arm 41 will be moved through the agency of the spring 46, which will wind up more or less in accordance with the resistance to movement As it would be inconvenient to observe the angular, relation of the arm 41 and the shaft 38 during the rotation of the parts, I

detent 53 carried by the arm.

provide means for locking the parts in their relative position during the movement of the tool over the work. As it-is also found preferable not to observe the starting force or the friction of rest which will be first indicated by the movement of the spring, I also provide means for locking thearm and shaft in their relative positions after the tool has acquired its full speed, so as not to indicate the abnormal force involved in starting the movement For this purpose, I have provideda lockin device comprising a sleeve 49 slidably Ireye-d to the shaft 38 andheld downwardly toward the arm 41 by a spring 50. The lower end of the sleeve 49 is provided with an enlarged flange 51 having a series of teeth 52 any one of which is adapted to coop rate with a uring the initial movement of the parts the. sleeve 49 is held in elevated position with the, detent 53 out of operative .relation with the teeth 52 "by means of a book 54 mounted on any convenient fixed part of the machine frame 39. After the tool 43 has acquired its full speed the sleeve 49 maybe dropped by releasing the engagement of the hook 54'so'that the detent 53 will engage one of the teeth 52 and lock the arm ll-with relation .to the shaft 38. i As illustrated in Fig. 5, the teeth 52 may be provided with any desired index numerals such as indicated at 55, so that the friction or resistance to movement offered to the tool by various wheels may be compared by refegence to these numerals.

It will be obvious that. the modification of the invention illustrated in Figs. 3-and 4: maybe provided with a measuring device similar to that shown in the preferred form of' the invention for measuring the wear on the tool 43. As illustrated, however, the tool would .beremoved from the arm 41 and measured by any convenient instrument such as the usualhand micrometer.

If it is desired to grade abrasive bodies by friction alone without considering tool wear, the tool may be of a relatively nonwearable material, such as a diamond, but. if the wear of-the tool is to be measured I prefer to use a tool of soft iron or steel not over A" in diameter on which the wear is large enough for convenient comparison. My improved method may. be carried'into practical effect by the machine's illustrated, if it is so preferred, by adjusting the pressure on the tool until a standard power is indicated on the dynamometer and then determining this pressure due to the weight acting on the tool. In this case, the weights 18 (Figs. 1 and2) 6r 44 (Figs. 3 and 4) are varied until a standard readingis obt-ained on the, scales 33 or 55 respectively and then a comparison of the weights required on any two wheels indicates their relative grades.

By the constructions described in connection with the two illustrated embodiments of k the invention, mechanism has been provided for? grading abraslve wheelsand similar objects by a method including the steps of holding a wearable tool in engagement with the body, giving them a relative motion so that an extended straight or curved path .will be generated by any point in the active face of the tool and thenmeasuring the drag or friction between the ,tool and the body and the amount worn from the tool. Both of these measurements are closely related to the grinding ability of the wheel and by the use of these characteristics the action of the wheel may be predetermined with much greater degree of accuracy than has heretofore been possible. It will of course be understood that the measurement of force may be made in accordance with any suitable standard scale or an arbitrary one which has not significance in engineering practice since the, apparatus may be used for.

comparative as well as absolute measurements; hence the claims are to be interpreted in this light.

What, I claim as new and desire to secure by Letters Patent is V '1: The method of grading an abrasive wheel comprising the steps of rotating the wheel at a fixed rate, causing a tool to bear against the wheel under a definite pressure and move along an extended path thereon and measuring a force which varies with and is produced by the friction between the wheel and the tool during such movement.

2. The method of grading an abrasive i wheel comprising the steps of rotating the wheel at a predetermined speed, causing a tool to engage the wheel and thereby generate. a circular path on the wheel, maintaining. a standard pressure between the tool and the wheel and measuring the force re ired to overcome frictioir between the tool and the wheel.

3. The'method of grading an abrasive wheel comprising the steps of rotating'the wheel at a predetermined speed, causing a tool of standard dimensions and material to beanagainst the wheel in an extended path, maintaining a co stant pressure therebe-: tween, determining the frictional and abrasive resistance between the wheel and the tool and comparing the data thus obtained with measurements similarly made upon standard wheels. 'f 1 4. The method of grading an abrasive wheel comprising the steps of cans? a wearable tool to bear against the wheel, relatively moving the wheel and the tool so that the tool will describe on the wheelan extended path, measuring the force of the frictional drag between the wheel and the tooland measuring the wear on the tool.; 5. A machine for abrasive wheels drag between the relatively moving wheel and tool.

6. A machine for grading abrasive wheels comprising means for rotatably supporting the wheel to be graded, a tool adapted to engage the wheel in a circular-path during said rotation, means to produce sure between the tool to resist movement of the tool under the frictional pressure of the rotating wheel and means to indicate the force necessary to resist such movement.

7. A machine for grading abrasive wheels comprising a rotatably mounted wheel supwheel and means port, a pivotally mounted arm carrying a tool adapted to frictionally engage a wheel on said support, a spring to control the position of the arm, means for adjusting the spring to position for measuring the force a definite pres-. and the wheel,'means the arm on a radius of the required by the rotating 'wheeL.

8. A machine for gradingabrasive wheels comprising a rotatably mounted wheel support, a pivotally mounted arm carrying a wearable todl bearing on a wheel on said support, means for measuring the friction between the tool and the wheel, means for moving the arm into a second position and means for measuring the tool" in the second mg on a wheel on said support, a spring to control the position of the arm in one plane,

means to indicate'the force exerted'on the spring by friction. of the rotating wheel on the tool and means for measuring the Wear on the tool when it is swung in the second plane. V Signed at Worcester, 20th day of Oct, 1919.

orLARn s is. GILLETT.

Massachusetts, this to hold the arm in such position I under the frictional drag exerted on the tool