US2620654A - Core hardness tester - Google Patents

Description

H. L. CAMPBELL coma HARDNESS TESTER Dec. 9, 1952 2 SHEETSSHEET 1 Filed Feb. 4, 1950 Patented Dec. 9, 1952 CORE HARDNESS TESTER Harry I3. Campbell; Oak Park, Ill., assi'gnor to Claud S..(3rord'onv Company, Chicago, 111., a. corporation of Illinois.

Application February 4, 1950', Serial No. 142,379

13 Claims. 1;

This inventionrelates to'a core-hardness tester, and more particularly to such device in which an abrading point is moved under predetermined pressure over a predetermined distance of travel against an exposed surface of a baked foundry core, for ascertaining the hardness of the core and its adaptability for making satisfactory castings for various kinds of work.

The making of foundry cores requires skill and care in selecting the right kind of core sand, and

. the rig-ht kind and proportions of binding ma terial to be addedto the sand; suchascore coinpound; molasses water, or whatever nature of binding material the particular-foundry-"is using in the making of its'cores. The-core sand and binding materials will vary in both kind and proportiomfordifferent-kinds of castings: One of the essential requi'rementsof foundry cores is that they have sufficient-porosity tocarry" oiT the gasesgenerated the-reinby theheat of the molten metal being poured therearound, and at the same have adequate strengtl'ito prevent breaking or crumbling that would result inanimperfect hole in the-casting. If thega-s generated-in the core during casting is not vented or relieved to the outside of the mold sufliciently quickly; cavities. called blow holes will be formed in the body of the casting, and possibly cause the casting to be'reie'cte'd.

For the above and other reasons, the core materials must be carefully selected and proportioned,v asrwell as properly compressed when the core is being formed, soas to meet themany core requirements for making good castings; After the cores have. been formed they are'baked in an oven; andibythe. use of the present invention one or more of the baked cores may be selected at random" and tested to" ascertain their hardness whiclr'wil'li'indicatez their suitability for thepariicuiar jobin which they are to be used, and whether the core mix should be changed. If desired avfew' test cores may he -first made, baked and tested, or such tests may be carried outfrom time to. time. and from day to day as thefoundry work proceeds, to ascertain Whether the coremix is satisfactory. If thebaked cores are too-hard they-Will not have the required porosity to carry the generated gases therefrom and out of the mold, and if too soft they will not stand up to-the required work. With the present invention it is thuseasily and quickly possible to test the 'baked cores to ascertain whether they meet the requirements of good foundry practice for'theparticular job. in which they are'tobe used.

Among the objects of this invention are: to

provide a new-and improved core hardness tester;

to provide a core hardness testerthat'is small and portable and can be readily carried around from place to place, can be easily and conveniently manipulated, and is efficient and accurate inoperation; to provide such tester having a stationary part within whichis mounted a rotatable portion provided with an eccentric abrading element, and means for indicating the amount of penetration of'the abrading element into the core after the abrading element has moved a predetermined distance, under a predetermined pressure, over the core surface; to provideacore hardness tester having means for abrading the surface of a baked core, and means for reading the'depth of abrasion to determine the hardness of the core; to provide a core hardness tester having an abrading element movableboth laterally and longitudinally, and novel means for indicating the amount of longitudinal movement of the abrad ing element when the tester'is operated against a baked core; and such further objects, advantages and capabilities; inherently possessed by the invention, as will later more fully appear.

My invention further resides in the combination, construction and arrangement of parts illustrated in the accompanying drawings, and while I have shown therein a preferred embodiment, I wish it understood that the same is susceptible of modification and change without departing from the spirit of the invention.

In. the drawings: I

Fig. l is a side elevation of my core hardness tester in the position indicating maximum hardness of. a core upon which it had been operated;

Fig. 2 is a bottom plan view of Fig. 1;

Fig- 3' is an enlarged, longitudinal section on a median. plane, parts being shown in elevation for clearness;

Fig. 4 is a top plan view of Fig; 3, but including the portions removed by section in Fig. 3-;

Fig. 5 is a view similar to Fig. 3, but showing the parts in a different relative position;

Fig. 6 is a top plan view of Fig. 5, but including the portions removed by section in Fig. 5;

Fig. '7 is an enlarged, fragmentary longitudinal section on a median plane, of the lower end portion of the tester; and

Fig. 8 is a transverse section on the line 8-8 of Fig. 5.

In the form shown in the drawings for illustrative purposes, and referring to Figs. 1, 3. and'5, my core hardness tester comprises generally a stem 1 having a cylindrical bore; 2, a supporting element 3 fixed onthe top' of the stem, a knurled wheel 4 rotatable on the supporting element, a shaft 5 rotatable with the knurled wheel but longitudinally slidable therein, an externally threaded head 6 fixed to the upper end of the shaft, a. knurled nut threadably mounted on the threads of the head 6, a cylindrical foot member 8 fixed to the lower end of the shaft to rotate and slide in bore 2, and abrading point 9 fixed eccentrioally to protrude from the lower face of the foot member, an annular ball bearing device ID resting on the upper face of the foot member, a ferrule above the ball bearing device, and a coil compression spring I2 between the ferrule and the supporting element 3. The tubular stem is of a length to be comfortably held within the grip of one hand of the operator. This stem has fixed at its lower end an outwardly extending flange 13, downwardly and outwardly beveled on its upper surface and with its bottom face M, as viewed in Figs. 3 and 5, falling within a plane at right angles to the longitudinal axis of shaft 5. Fixed to the lower face M of flange I3, at suitably circumferentially spaced points, are any suitable number of short, sharp-pointed pins l5, sufficiently small to be readily embedded a short distance into the surface of a baked core being tested so as to prevent the tester from slipping with relation to the core, and yet prevent any penetration damage to the core during testing. Three of such points are shown for illustration in Fig. 2.

The supporting element 3 has an outer marginal edg circular in contour and formed its vertical face with a circumferential groove I6 extending entirely therearound. On its under face, supporting element 3 is formed with a downwardly extending annular flange ll fixed in any suitable manner in the top of stem l, to be stationary therewith during operation of the tester. Supporting element 3 is provided with a central opening l8 within which shaft 5 .is rotatable and longitudinally slidable.

porting element but permit free rotation thereon. Three of such studs are shown for illustration, see Fig. 8, but any other number may be used as desired. Fixed by screw-bolts or the like 2|, to the under face of supporting element 3, is a radially extending stationary arm 22, having its outer end turned upwardly to form an index member 23, the upper end of which flush with the upper face of the knurled wheel 4 and formed with a radial stationary index line 24. Also formed at a desired marginal location on the upper face of knurled wheel 4 is a radial index line 25 which moves with relation to the stationary index line 24 as the knurled wheel 4 rotates on the supporting element 3.

The externally threaded head 6 is fixed to the reduced diameter portion 26 of shaft 5, preferably with a set screw, as indicated at 2'! in Figs. 3 and 5, the outer end of this set screw when tight being inside of the outer surfaces of threads 28 of the head, so as to permit the inside threads 29 of knurled nut 1 to freely pass thereover when the knurled nut is being rotated thereon. When the threaded head 6 is fixed on the reduced end of the shaft, it will be positioned with its lower face bearing against the shoulder 38 formed between the reduced end and the main portion of the shaft. As will be seen in Figs, 3 and 5, the externally threaded head 6 is formed with only three threads at the bottom portion of its external surface, the remaining portion being unthreaded and of a diameter slightly less than the root diameter of the threads thereon, so as to be sure and clear the threads on the inside of the knurled nut l. The outer annular corner of the top end of head 6 is beveled to provide a slanting surface 3| which is of the same angle as the upper beveled slanting surface 32 at the top of the knurled nut i, so that these two slanting surfaces will form continous, uninterrupted surfaces when they are brought into registry, as shown in Fig. 3. For this purpose the threads on the inside of this nut are terminated a slight distance short of the top of the nut where they merge into an inner cylindrical surface freely rotatable on the unthreaded side portion of the head 6, and of a diameter slightly greater than that of said unthreaded side portion. This enables a quick detection of the registry of slanting surfaces 3| and 32.

It is also to be noted that when slanting surfaces 3| and 32 are in registry, the bottom surface of knurled nut 1 and the bottom surface of head 6 fall in the same plane, which, when the abrading point 9 is free and out of contact with any object, is also the plane of the upper surface of the knurled wheel 4. At this same time the point of the index marker 33, stamped on the slanting surface 3| of the head 6, will point to the radial line bearing the numbers 0, 50 and as stamped on the slanting surface 32. This latter surface also has stamped around its inside edge, circumferentially equally spaced marks and numbers from 5 to 45, and on its outside edge similar marks and numbers from 55 to 100, for a purpose later more fully explained.

Knurled wheel 4 is also formed with a central opening 34 Within which shaft 5 is longitudinally slidable but is prevented from rotation therein by a key member 35 integrally fixed to knurled wheel 4 and seated in key slot 36 over which key member the slot is longitudinally slidable. In this connection see Figs. 3, 5 and 8. This construction causes shaft 5 to be rotated with knurled wheel 4, and to be longitudinally slidable therein. As seen in Figs. 3 and 5, the coil compression spring I2 is seated at its top end in the recess 3'! formed in the bottom face of the supporting element 3, this spring surrounding shaft 5. At its bottom end spring I2 is seated over the upstanding tubular neck 38 of ferrule II to bear against the lateral annular flange 39 thereof.

As seen in Fig. '7, the ferrule H is slidably mounted on the shaft 5 to be rotatable with relation thereto, and is provided with a downwardly extending integral sleeve or neck 40, which is loosely inserted within the inner circular opening of the annular inner ball-race member 4|, within the latter of which are rollably seated a series of anti-friction balls 42 which, on their opposite face, rollably contact the annular outer ball-race member 43 which is fixed within the annular-ball-bearing casing 44 which in turn is slidably mounted within the bore 2 of acac a-54.-

stemil andrests atiitsbottom: on the-foot-mem her 81. The inner ball-race member 41 is 1:0 tatably slidable with:v relation. to the bottom flange: of casing 44'." This ballbearing' assembly asdescribed above, and. indicated generally in Figs. 3: and 5,. at llli, is a. conventional; device obtainable on the market.

The abrasionv member 91 is. a steel pin, adjustably fixed in hole 45. in. the. foot membenit by a. set screw 46; for longitudinal; adjustment. as desired. The bottomen'd" of. this pin is tapered to asharp point 41, see-Fig.7, and is eccentrically located. in foot. member: 8 so that when. shaft 5 isrotatedz under pressure of spring I.2,. this abrading point will rotate in.a circle and scratch into a; baked. core against. which: the tester is. posie' tioned. In the position. shown. in Figs 5 the shaft 5 has: been rotated. for. three: revolutions, which caused the abrading point. 413'. under: the constant pressure offspring t2, to travel imamcircle' against the surface? of the core. 48' and, during: such travel, dig intosthe bodyof the baked core to a 01250 inch. in. length from where it begins: to

taper to the tipof the point, and thepins I 5 arersharppointed and. merelylong enough to prevent slipping of. the bottom face it of the testerwhena the knurled. wheel 4. is rotated with theitester pressed against the core. The. threads 28 011113116 head 6- are made with a: pitch of one eighth of. an inch, or in other words, eight threads to theinch; This means that one revolution of the knurled nut l will move it one eighth: of an'inch with. relation torthe' head, and. tworevolutions will: move: it one quarter. of

inchz thereon.

r The operation of-. the device will be under:- stood' fromthe above: description; The maximum hardness value indicated'by the. hardness tester islOO for zero penetration. When the abrading point moves: down adistance of 0.250: inch,. the hardness of the core is Intermediate values cam-be found withinvthese twoextremesras: indi catedby the scale. When. a: reading ofiO is re-- ferred to, it means that: the marker index point 33ionthe slanting surface 31- of. thehead' 6 stands opposite the: 0-50-100' lineon'the slantingv surface 32 of. the. knurled nut. 'l, with. these two: slanting surfaces in registry and the bottom faces. of the. head' and nut in the same plane andresting om the top surface of the knurled. wheeli 4 This means that the tester was pressed. against a baked core. flat surface with: the head: and nut standing at. 0, and: the knurled: wheel. 4 rotated three: revolutions; starting and stopping with the fatten-point- 25' of? the-wheel in registry with the index line: 24- of the index arm 2223 During these. three revolutions the. abrading point 4:! cut intothe-core a. distance: of one-quarter of an inch; with the topof' the taper in the plane of the bottom. face it ofthe stem flange l3 as seen in Fig. 7, and with the: bottom faces of the head and nutcontacting the upper face of the. wheel,. thus-- indicating, that: the. core Wasof 6 0 hardness. A space still intervenes. between thertop. of the taper of the pin and thebottom face of the. foot member 8;v to receive any loose particles forced up thereinto by the: abradingi point.

Again,. with the head andinut' standing: at 0 with relation to each other, and with the? tester pressed against a baked core flat surface, if the. wheel 4 is rotated: three revolutions and: the abrad'ing point. still stands in. the position. shown in. Fig; 3- with no penetration into the core, a rotation of the nut l: clockwise. for: two revolutions. will be required, with the Wheel 4 held stationary, in order? to make the bottom surface: of the nut touch the top surface ofith'e wheel,. which will bring the marker" index point 33 in registry with" the 0-50-100 line, thus reading on the outside,v because of the tworevolutions of the nut. This: I00 reading after: two clockwise revolutions of' the nut indicates that the core being tested is of maximum hardness with zero: penetration of the abrading point- Afterthe-three revolutions of the Wheel, preferably in a clockwisedirection, and the clockwise rotation. of the nutuntilzit touches thewheeLwith the. tester during. this time being. pressed against the core, the. tester may then'be removed from the core and the reading read on the top of the nut with relation to: the index 33 on thetop of the head 6 Any'interme'diate degrees of penetration of the: abrading point into the core may likewise be read nthe scale,

In other words, to: make a hardnessit'est of any baked core desired to be: tested, set th pointer or line 25' on the wheel in registry with". the stationary index line 2 4, turn the knurled nut 1 until the two slanting surfaces are evem; with marker point 33' opposite the zero" on indexf line 0 -50400; place. the tester on a fiat. surf'acrez'v of the core and hold the.- testerv against the corewdth one. hand'while. the: wheel 4' is turned: clockwise for a total; of; three. complete revolutions; and: with the tester'still held against? the core turn thernut 1 clockwise (to move it downwardly") until it touches the wheel 4.. Then lift: the testenfrom the: core and. read. the. hardness: value on the" dial opposite the arrow on the central head... The inside figures onthe: dial. are for the first revoluetionof the" nut and. the outside figures:- are for the second revolution of thenut.

To check theinstrument, see that. the end; of the-'abrading point is even: with the bottom. ot the: tester when'the dial is. at: 100; Alia reading of 0; when the two slanting surfaces: are in line, the abra-di'ng. point extends 0.250 inch from. the bottom of the instrument;

Hardness.- readingscan be taken. on. horizontal-,1 vertical; or intermediate: surfaces, as well: as in recesses. When the required'hardness standards are established for a given practice, the condie tion. of any core can. be determined quickly and easily.

While-it has been stated that abrasion member 9-- is a steel pin,. itis to be understood that thesame is very hard tobe abrasive resistant, or it may be. of any other material sufliciently hard to maintain its sharp point for long durations 0t. use.

Also while Iv have, for illustrative purposes; shown and described my hardness tester as applied to the testing of the hardness of" bakedfoundry cores, I wish it understood: that it may be employed for the testing of the hardness: or plaster; plaster-of-P'aris, mortar, soft pfasticgand any other: material of. semi-hardness to which it. may be. adaptable.

I claim:

1. A hardness tester, comprising, a stem having a supporting element fixed to one end, a shaft mounted in said stem and supporting element for rotation and longitudinal movement therein, a wheel member rotatable on said supporting element for rotating said shaft, the shaft also being longitudinally slidable through the wheel member, a threaded head fixed to the shaft beyond said wheel member, a nut threaded to move longitudinally on the head, an abrading element eccentrically mounted on the end of the shaft removed from said head, and a scale on one of said nut and head and an index marker on the other for indicating the value of penetration of the abrading element into a surface being tested.

2. A tester as claimed in claim 1, including a spring connected to the shaft and stem for urging the shaft and abrading element in a direction away from said supporting element at a predetermined pressure.

3. A tester as claimed in claim 2, including a foot member at the bottom portion of said shaft in which said abrading element is fixed, an annular anti-friction device resting on the foot member, and an annular ferrule bearing against said anti-friction device and against which said spring exerts its pressure.

4. A tester as claimed in claim 3, in which said spring is a coil, compression spring surrounding the shaft and bearing against the ferrule at its lower end and against the supporting element at its upper end.

5. A baked foundry core hardness tester, comprising, a tubular upright stem, a circular supporting element fixed to the top of the stem and having a circumferential groove around its outer edge, a wheel member rotatable on the supporting element and having an annular depending flange encompassing the outer edge thereof, adjustable and removable means at spaced intervals around the circumference of said flange to enter said groove to enable r0- tation of the wheel on the supporting element but prevent separation thereof, a shaft rotated by rotation of the wheel member but longitudinally slidable therein, said shaft being rotatable in the supporting element and in the stem, an eccentric abrading element mounted in the bottom end of the shaft, said shaft extending above said wheel member and having a threaded head fixed thereto, a nut threadably mounted on the threads of the head, and a scale on one of the nut and head and an index marker on the other, for reading the amount of penetration of the abrading element into a core after rotation of the abrading element on the core and when the nut has been screwed down until it touches the wheel member.

6. A tester as claimed in claim 5, in which the supporting element and the wheel member have respective index marks to enable a predetermined amount of movement of the wheel member and the abrading element.

'7. A tester as claimed in claim 6, in which a coil compression spring encircles the shaft and bears at one end against the shaft and bears at the other end against the supporting element to exert a predetermined downward pressure on the abrading element,

8. A hardness tester, comprising, a tubular stem having a supporting element fixed to the upper end thereof, a wheel member rotatably mounted on said supporting element, a shaft extending into the stem and rotatable in the supporting element and rotatable with the wheel member, said shaft being longitudinally slidable through the supporting element and the wheel member and extending beyond the top of the latter, an externally threaded head fixed on the top end of the shaft, a nut threadably mounted on the threads of the head to move up and down with relation thereto upon rotation of the nut depending on the direction of rotation, an enlarged foot member fixed on the bottom of the shaft, a ferrule on the shaft, an anti-friction device between the ferrule and the foot member, a coil compression spring bearing against the ferrule at one end and against the supporting element at the other end, and an eccentric abrading point fixed in the lower face of the foot member of the shaft.

9. A tester as claimed in claim 8, in which a scale is mounted on the nut to cooperate with in index marker on the head, and an index marker is provided on each of the supporting element and the wheel member to enable counting of the number of full revolutions of the wheel member on the supporting element.

10. A tester as claimed in claim 9, in which the ferrule is formed with a radially extending flange to seat the ferrule on the anti-friction device, and to receive the thrust of the lower end of the compression spring.

11. A hardness tester comprising, a stationary tubular stem, a rotatable and longitudinally movable shaft in said stem, an eccentric abrading point on the bottom end of said shaft, a wheel for rotating said shaft, the shaft being longitudinally slidable in the wheel and rotatable therewith, a spring for normally urging said shaft longitudinally downwardly, and a twopart member on the upper end of the shaft, one part of the two-part member being fixed to the shaft, and the other part thereof being longitudinally movable with relation to said one part to measure the value of downward movement of the abrading point when testing the hardness of a material being tested.

12. A hardness tester, comprising, a tubular stem, a supporting element fixed to the top of the stem, a shaft rotatably and longitudinally movable in said supporting element and having a foot member assembly at its lower end, a wheel member rotatably mounted on the supporting element, resilient means for normally urging said shaft downwardly, a downwardly extending abrading element eccentrically fixed to th lower face of said foot member assembly to rotate with the shaft, and means on the top portion of the shaft above the wheel member to indicate the value of hardness of an article against the surface of which the abrading element is moved under pressure by rotation of the wheel member and shaft, the wheel member and the shaft being interconnected for rotation togethe but with longitudinal movement of the shaft with relation to the wheel member.

13. A hardness tester, comprising, a stationary member, a shaft mounted in the stationary member for rotation and longitudinal movement therein, an abrading member eccentrically mounted on one end of the shaft, a Wheel member rotatable on the stationary member and interconnected with the shaft for providing rotation and longitudinal movement of the shaft with relation to the wheel member, said abrading member being movable along a closed circular path a plurality of times when pressed against a surface to be tested during rotation of the shaft.

and means on the tester for measuring the value of the penetration of the abrading member into said surface when the abrading member has moved over said path under a predetermined pres- HARRY L. CAMPBELL.

REFERENCES CITED Number UNITED STATES PATENTS Name Date Guillery Mar. 24, 1914 Tone Oct. 29, 1918 La. Vercombe Nov. 14, 1922 Craemer Sept. 11, 1934 Dietert Sept. 13. 1938 Podesta Jan. 4, 1944

Images