US1830842A - Hardness testing machine - Google Patents

Description

Nov. 10, 1931. H. H. LA VERCOMBE 1,830,842

HARDNES S TESTING MACHINE Filed Aug. 28, 1925 2 Sheets-Sheet l NOV. 10, 1931. VERCOMBE 1,830,842

HARDNES S TESTING MACHINE Filed Aug. 28, 1925 2 Sheets-Sheet 2 57 l-. Zlwuentoz:

Patented Nov. 10, 193 1 UNITED STATES PATENT OFFICE HARLEY H. IA vnncomnn, or DETROIT, MICHIGAN, ASSIGNOR 'ro ABRASIVE ENGINEER- ING CORPORATION, or DETROIT, MICHIGAN, A. CORPORATION or MICHIGAN HAnnNEss TEs'rINe MACHINE This invention relates to means for testing "the hardness of grinding wheels, stones and similar material and articles which 1t is desirable to grade according to set standardsso that uniformity in such grading may be secured and the relative hardness of difl'erent grinding wheels or stones ascertained in order to determine their suitability for different uses, and to that end it has heretofore aflected by such impacts.

The hardness which it is desired to ascertain is that which results from the natureof the material forming the grinding wheel or stone as a composition or structure and is not necessarily governed by the size or nature of the grains of the abrasive material. For instance it may be governed by the nature of the matrix in which the abrasive material is embedded.

The success of'comparative hardness tests must necessarily depend upon identical or definitely related circumstances governing the treatment -of different stones which are to be so compared, otherwise the conclusions arrived at would be unreliable, and it is the object of this invention to provide, in a hardness testing machine, for the ensuring of the carrying out of such tests under practically identical conditions as to duration ofoperation, frequency of im acts, power expended in such impacts, and t e manner of their delivery and reception so that proper compari son as to results'of the tests on different wheels or stones may be made. 1

The invention also is intended to provide for variation of the length of stroke of the impact drill and also variation of the power I expended in such impacting stroke; a further object of the invention being to provide for the determining ofthe number of blows to be delivered by the drill in an-operation, and the duration .of such operation.

Further objects of the said invention are to provide for themounting of the grading 'drill on a spindle which delivers its blows inafter In carrying the said invention into efiect,

Application filed August 28, 1925. Serial Roi 52,975.

n'ating the lack of uniformity which is liable,

to result .from the useof springs, and to further facilitate such gravital operation by the mounting of the said spindle in roller guides.

It is also an object to provide for the rotation of the spindle by the rotation of said rollers around the axis of said spindle between each impact, whereby a flat drill may be caused to produce a round hole or depression in the surface of a wheel or stone submitted to e the impact of the said drill throughout a period of operation.

The invention also contemplates the provision of durable indexing and ratchet mechanism controlling and effecting the duration and frequency of the impact and the rotation of the grading spindle, and also the provision of an indicator giving a direct reading of the depths of penetration without necessitating the removal of the wheel or stone from the machine, or such interference with the setting of the machine as might preclude or complicate the further continuance of the test if so desired. a

Further objects are to provide means associated withthe grading table upon which the wheel rests during a test, particularly intended to efl'ect the local supporting of the wheel or stone directly beneath the dull; and to provide a simple form of chuck eminently adapted to use in a machine of this type.

Stillfurtherobjectssubsidiary to or resulting from'the aforesaid objects, or from the construction or o ration of the inventionas it may be earned into effect, will 'become ap arent as the said invention is hererther disclosed.

I may provi in a hardness testin machine for facilitating the gradin of articles such as grinding wheels, a gra ing table for the support of a inding wheel, and a drill spindle vertical y reciprocal above saidtable by means of a mechanically actuated liftin member which releases the said spindle an permits it to fall by gravity, a drill or impact tool mounted in the 'lowerend of said spindle which strikes the surface of the grindstone each time the spindle falls, and

ratchet means synchronized in operation with the lifting member, partially rotating the said drill between each blow delivered to the said grindstone.

An adjustable dial device controls the duration'of the operation of the lifting androtating mechanism, and stop means, set by the said dial, ensure the cessation of the operations when they have been effected to the predetermined extent; and an indicator is adapted to be brought into operation at any stage in the test to indicate the pene tration of the grindstone effected by the drill and to give a directreading of such penetration, means being providedfor the setting of such indicating inechanisinto provide for different thicknesses or dispositions of the grinding wheels relative to the drill or for difl'erent lengths of drills which may be utilized. The said grading spindle reciprocates between friction reducing rollers which rotate therewith and about the axis thereof and are mounted in a suitable housing adapted to ratchet rotation whereby the aforesaid rotation of the spindle is effected. An adjustable member is adapted to be brought to liealii on the grindstone directly beneath the All of which is more particularly described I and ascertained hereinafter, by way of ex.-

ample, having reference to the accompanying drawings, in which Fi re 1 is an elevation of a machine embodymg my improvement; I Figure 2 is a side elevation of the same;

Figure 3 is a plan of the same;

v Figure 4 is a similar view to Figure 3, with i Mounted'on a pedestal 1 is a gear casing 2, from the upper end of which extend arms 3 carrying the drive-shaft 4 which is provided with a drive pulley 5 and a V-pulley'6 belted to a similar pulley 7 on the end of a worm gear shaft 8 journaled in the lower part of the said gear-cashig. This shaft 8 through aworm 9, worm gear 10 and its spindle 11 efl'ectsthe rotation of the lower part 12 of a dog clutch, the upper part 13 of which" is mounted on the lower end of a vertical spindle 14 journaled in 'a member 15-of the gear casing and carrying an eccentric 16 and 'a cam 17 at the upper end thereof.

It will be seen that the upper part 13 of the dog clutch is vertically movable on its spindle by a clutch fork 18 mounted on a shaft 19 extending transversely of the gear casing and operable by a clutch lever 20 exterior to the said casing, which lever is subjected to the influence of a tension spring 21 which tends to retain it in a depressed posi- 'tion and therefore tends to effect the disengagement of the clutch 12, 13. The said- -clutch leveris, however, provided with a dial latch 22 adapted to ride over the periphery or engage in a peripheral notch 23 of a rotary dial 24, according to 'the position of the said dial relative to the latch 22, for purposes which will be hereinafter further explained.

Extending forwardly of thesaid gear casing is a head 25 through which vertically passes a reciprocal and rotatable spindle 26 I mounted between upper and lower pairs of rollers 27 and 28, whereby its very free vertical movement is permitted. The said spindle is not rotatable with respect to the said rollers, but these rollers are mounted at the upper andlower ends of -a sleeve 29 in the head .25; which sleeve is provided with a ratchet 30. The rotation of the said sleeveis accompanied bythe rotation of the said 1 spindle 26 and such rotation of the sleeve is efi'ected by the movement of a pawl 31 extending from a strap 32 mounted upon the said eccentric 16, which pawl engages the teeth of the said ratchet successively with each revolution ofthe said eccentric 16. 33 is a dog locking the ratchet against reverse rotation, the said pawl'31 and dog 33 beingheld in operative relation to the ratchet by a tension spring 34. s

Reciprocation of the said spindle is effected througha lever 35 by the cam 17 which in each revolution raises the said lever and causes it to strike the-underside of a plate or weight 36 on the upper end of the said spindle, the said lever being swingably Ihounted on a shaft 37 in the gear casing and provided with a roller 38 beneath which the said cam- 17 passes. The weight 36 may be replaced vby difi'erent weights'to suit circumstances of op-' eration. y On the inner end of the shaft 37 is a ratchet wheel 39 and a gear pinion 40 which, through a train of gears 41, 42 and 43, eifects the rotation of the dial 24 upon the actuation of the ratchet wheel 39 by a pawl 44 carried by the said lev'er'35.

From the foregoing description it will be understood that one revolution of the cam 17 and eccentric 16 is accompanied by the lifting of the spindle, a partial revolution thereof while raised, the release of the spindle so that it may fall by gravity, and the partial rotation of the dial 24; a ratio of gearing which'I have found useful in this device re-.

sulting in one complete revolution of the dial 24 to six hundred. revolutions of the said strokes of the spindle-26.

cam 17 and consequently to six.hundred The lower end of the said spindle 26 is provided with a chuck 45, a preferred form ness of the said stone, and the .frequency and force of the impact is determined by the number of revolutions per minute of the cam 17 and the stroke and weight of the spindle 26. J

Furthermore, the duration of the operation, in other words the number of strokes required of the spindle 26, may be determined by rotating the dial 24 so as to vary the relative position of the notch'23 thereof to the latch 22 and thereby determine the extent of rotation of the said dial required to permit the latch to engage in the said notch 23 which determines the number of revolutions of the cam 17 which will be required to permit such engagement of the latch with the said notch.

' The said dial may be indexed as at .47 to facilitate its proper setting for any desired number of revolutions of the said cam 17 and also may be frictionally mounted upon its shaft 48 to permit of its adjustment.

For the support of the grinding wheel or abrasive material, a table 49 is provided beneath the said spindle 26 and also beneath a jaw 50 extending from the lower. part of the said gear casing, this table being verticalraising or lowering the position of the weight on the spindle such as by the use of shims 85..

It is preferable that adequate support be given, especially in the testing of compara-v tively thin wheels or material, to the underside of the material immediately beneath the impacting drill, and as sometimes there are depressions in such underside which would not be properly supported by a flat table of any considerable area it is proposed to provide the table and its support with a bore 55 in the lower end of which a compression spring 56 is accommodated and from the upper end of which projects a lunger 57 supported by the said s rm the grinding wheel e .p aced upon the said table 49 clamped thereby beneath the onsequently, if

jaw 50, this plunger will bepressed by its spring into engagement with that part of the underside of the grinding wheelimmediately beneath the drill 46, even though there may be a depression at this point, and the said plunger is then clamped firmly into such engagement with the a set screw 58.

When the machine is operated the spindle is successively raised to a definite height,

grindstone by means of turned while the tool 46 is out of contact with the material being tested, and allowed to fall with a definite impact for a number of times determined by the setting of the dial 24, as explained, the partial rotation of said spindle and its drill between impacts forming a round hole or depression in the surface of the grindstone; and since the force of impact is equal with each blow (excepting insofar as the stroke is slightly increased by the depth of the depression formed, which is negllgible) a very definite force is expended in any determined number of impacts.

Therefore, two wheels of equal hardness, as it is understood in a test of this nature,

will show resultant depressions by the drill of equal depth if tested under identical conditions. The depth will be greater in the case of a wheel of lesser hardness and less in a wheel of greater hardness. Thus a series of wheels may be so tested and graded as to their hardness by relatively measuring the depth of depressions formed in them by an equal number of impacts in each case, or, on the other hand, by comparing the number of impacts required in each case to produce depressions of equal depth. i

I facilitate the ready reading or determining of such hardness by the provision of. means which will visually indicate the result of a test in a very simple manner, such means consisting of a bell crank 59- fulcrumed at 60 to the gear casing, the horizontal arm 61 of i the said bell crank being provided with an adjusting screw 62, the end of which rests upon a projection 63 on the upper end of the spindle 26, 64 being a locking screw for securing the set screw in adjusted positions.

"Also mounted upon the upper part of the gear casing is an indicator 65 having an operating pin 66 projecting therefrom in the direction of thevertical arm 67 of the said bell crank lever; and before commencing a test upon a grinding wheel or other piece of abrasive material, the spindle is permitted to descend until the drill fully rests upon the surface of the said grinding wheel after a tive position and the test proceeded with, the dial '24 being first set with the index showing the number-of impacts of the drill upon the grindstone to be made.

The machine now being set in operation by the driving of the pulley 5 by an suitable means, the drilling takes place an the dial 24 gradually revolves until the latch 22 is coincident with the notch 23 of the said dial, whereupon the tension of the spring 21' causes the latch to enter the said notch which is accompanied by the disengaging of the upper part13 from the lower part 12 of the clutch due to the depression 0 the clutch lever 20 by the said spring 21. This results in the cessation of the operation of the-machine.

After the operation of the machine has ceased, the bell crank is again brought 1nto operative position relative to the spmdle which is in a position of rest with the drill bottoming the depression formed thereby in the grindstone, and consequently the vertical arm 67 of the bell crank will actuate the pin of the indicator to an extent relative to the depth of such depression so that the indicator will be operated to show such depth. Upon the insertion of another wheel or stone in the machine for testing, the adjusting screw of the bell crank .is again reset, if required, to insure the proper zero setting of the vertical arm of the said bell crank relative to the indicator and the test again proceeded with as before, and if with the same setting of the dial 24 as used in the previous test the same reading is secured on the indicator when the bell crank is brought into operation as was secured in the previous test, the two wheels or stones so tested may be graded as of equal hardness, but if a greater depression be indicated the stone so tested would be graded as of lesser hardness, or vice versa.

I prefer to use a chuck such as that shown in Figures 7, Sand 9, wherein a tubular head 7 2 receives a-jaw 73, one arm 7 of which jaw is longer than the other arm 75.. The longer arm 7 4 projects beyond the end of the head 72 'to facilitate the insertion of the drill into the groove 77, as the flat side of the drill may be simply engaged with the inner side of the projecting end of the arm 74 which guides the drill into the groove. 78 is a set screw securing the jaw in the head and 7 9 is another set screw in the hea by means of which the drill is clamped be ween the arms of the jaw. Where a considerable amount of testing is to be done it is usually advisable to frequently change the drill as it becomes worn and the provision of a chuck such as that described greatly facilitates this changing operation.

A machine-of this type if properly constructed isvery positive in its operation. and indications, and affords a means of readily obtaining comparisons of the hardness of different grinding wheels, stones or abrasive materials,irrespective of other qualities which are often confounded with true hardness as properly understood in this art and which very often lead to improper rating of abrasive materials.

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 specificationand drawings be read as merely illustrative and not in a limiting sense, except as necessitated by the prior art.

WhatI claim is 1. In a machine for testing the hardness of abrasive and similar materials, a reciprocal drill member, a drill carried thereby, means for supporting material to be tested in opposition to said drill, means effecting the recip- Y in opposition to said drill, means effecting the reciprocal movement of said member whereby said drill is caused to frequently strlke the presented surface of said material,

, timing means determining the number of reciprocations of said member, and stop mechan1sm controlled by said timing means, said stop mechanism rendering said member inoperative when such number of reciprocations has taken place.

3. In a device of the class described. means for supporting the material to be tested as to hardness, impacting means adapted to be brought into frequent contact with a localized area of said material on said supporting means, and a member adapted to be projected from the surface of said support for the local I supporting of said material directly beneath the impacting means.

4. A device according to claim 3, wherein the-main supporting means for said material is 1n the form of a table and said supplementary supporting means in the form of a spring pressed plunger extending beyond the surface ofsaid table, whereby it may enter depressions in a material supported on said table and a lock securing said plunger rigidly in its engagement with said material. j

5. In a device of the class described, in combination, a reciprocal drill member, a cam mechanism effecting the reciprocation of said member, said mechanism including a clutch, declutchlng means, and timingmeans operatmg said declutching means upon the completion of a predetermined number of reciproca- .tions of said member.

6. In a device of the class described, in

combination, a reciprocal drill member, a cam mechanism effecting the reciprocation of said member, said mechanism including a clutch, declutching means, and timing means operating said declutching means upon the completion of a predetermined number of reciprocations of said member, said timing means be? Y ing actuated by said member.

7 In a device of the class described, in

combination, a reciprocal drill member, a cam 10 efiecting the reciprocation of said member,

cam operating means, means for disconnecting said cam Irom said operating means, said disconnecting means being geared to said operating means and adjustable for disconnecting the cam upon the completion of a predetermined number of reciprocations of said 8. .ln a device ofthe class described, in combination, an impacting device, means'for operating said device, aciutch in said means,

declutching means, and timing means operated by said operating means and operable on said declutching means, sai d timing means being adjustable to operate said declutching means on the completionof a predetermined {Lumber of movements of said impact memr. 9. A method of testing the hardness of abrasive and similar materials consisting in 3b applying to said material a known number of impacts with a straight-edgeddrill, turning a said drill through a small angle between im;

pacts and while out of contact with thematerial whereby a round hole is formed in said material, and measuring the depth of said hole after a known number of impacts has been applied.

10. A method of testing the hardness of abrasive and similar materials consisting in 40 applying to said material a known number of impacts with a straight-edged tool with a v striking end of an appreciable area, turning said tool through a small angle between impacts and while out of contact with the material, whereby a round hole is formed in said material, and measuring the depth of said hole after a known number of impacts has been a plied. 11. a machine for testing the hardness so of abrasive and similar materials, a reciprocable s indle, a straight-edged impact tool carrie thereby and having a striking, end of an appreciable area, means for supportin material to be tested in opposition to sai tool, said means engaging the material over an area directly beneath that struck by said tool, means for raising said s indle and tool, means for turning said spin ewhile raised, and means for withdrawing support from said spindle while raised, whereby said spindle falls and said tool strikes the material' to be tested. In testimony-whereof I aflix my signature.

HARLEY H. LA VERCO E.

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