US3855848A

US3855848A - Hardness testing machine

Info

Publication number: US3855848A
Application number: US00314346A
Authority: US
Inventors: M Sidler
Original assignee: SKF Compagnie dApplications Mecaniques SA
Current assignee: SKF Compagnie dApplications Mecaniques SA
Priority date: 1971-12-21
Filing date: 1972-12-12
Publication date: 1974-12-24
Anticipated expiration: 1991-12-24
Also published as: FR2165164A5; DE2260614A1; GB1385940A; DE2260614B2; IT974181B

Abstract

A machine for testing hardness by the Rockwell method and apparatus includes a single lever permanently supporting a preloading weight positioned on the same side of the lever fulcrum as the operative connection of the lever to a penetrator, and, on the free end of the lever, an attachment to a main weight, all moving parts being articulated and guided exclusively by transversely elastically flexible but longitudinally nonextensible blades which are restrained at their ends.

Description

limited States Patent 1191 Sidler [4 Dec. 24, 1974 [54] HARDNESS TESTING MACHINE 2,333,747 11/1943 $111111 73 113 3,416,367 12/1968 E t r. 73/81 X [75] Inventor: 2 2 Le vesmett 3,443,422 5/1969 H rzberg 73/81 ra e Q FOREIGN PATENTS OR APPLICATIONS [73] Asslgnee' D Appl'cat'ons 919,437 1954 Germany 73/81 Mecanlques, Clamart, France e [22] Filed: Dec. 12, 1972 4 1 Primary ExaminerRichard C. Queisser Assistant Examiner-Stephen A. Kreitman pp 3141346 Attorney, Agent, or Firm'McGlew and Tuttle Foreign Applicati on Priority Data '1 [57] ABSTRACT Dec. 21, 1971 France 71.45860 A ma ne f r t sting hardness by the Rockwell 4 method and apparatus includes a single lever perma- [52] U.S. Cl. 73/81 nently supporting a pre-loading weight positioned on [51] Int. Cl. G01n 3/44 the same ide of the lever fulcrum as the operative [58] Field of Search .1. 73/81, 78, 83, 85, 141 A; nne i n of the l r to a p n on 177/229, BIG 9 free end of the 1ever,.'an attachment to a main weight,

all moving parts being articulated and guided exclu- [56] References Cited sively by transversely elastically flexible but longitudi- UNITED STATES PATENTS nally non-extensible blades which are restrained at 1,141,881 6/1915 01561.; 1. 73/81 ends 5 1,646,195 10/1927 German 73/81 11 Claims, 7 Drawing Figures 1 11. Z 9 Y 7 a 3 o 71 2 A 72 l i yl l l 25 79 PATENIED [181241974 SHEET 1 [If 2 I I-IARDNESS TESTING MACHINE FIELD AND BACKGROUND OF THE INVENTION The technical province of this invention is that of to allow a pyramid-shaped diamond point to be applied to the material to be tested. The penetrator is initially subjected to a minor load and thereafter, at a diminished rate of penetration controlled by a damper, to a major load which is removed after a given time lapse. The test is completed by reading, on a dial gauge, the residual penetration due to the effect of the major load.

In known testers of this kind, the penetrator, which is supported on a sliding device (usually a ball cage), has applied thereagainst, through the agency of knifeedge articulations, two levers pivotally mounted on ball-bearings or knife-edges. One of the levers supports the minor pre-loading weight positioned on the same side of its fulcrum as the knife-edges bearing against the penetrator, and the other end of this lever continuously actuates the feeler of a dial gauge- The second lever is provided, on the same side with respect to its fulcrum bearing, with a knife-edge contacting the penetrator, through an intermediate window therein providing a predetermined clearance, with a damper and with means for permanently attaching the major load-forming weight.

All such components, like the ball-bearing articulations, sliding cages and the like, though claimed to im prove precision, in fact introduce many factors of inaccuracy 'which make this alleged improvement illusory.

' Further, the mechanism is complex and costly, and

moreover the speed and time of application of the minor load are imprecise, as is also the rate of penetration due to the major load (as controlled by the damper), whilethe time of application is left to the operators initiative and is not constant. These random factors are likewise detrimental to the accuracy of the measurement.

SUMMARY OF THE INVENTION It is the main object of the present invention to overcome these drawbacks by providing a hardness testing machine of this kind in which a single lever, permanently supporting a pre-loading minor weight, includes means for attachment to at least one major weight and means for attachment to a' penetrator, the single lever being pivotally supported at a fulcrum point by a pivot having crossed non-extensible flexible blades and being connected to the penetrator by a non-extensible flexible blade preferably working in compression, the penetrator itself being provided, like a major-weightsupporting rod, with guidance means formed in each case by at least one pair of non-extensible flexible blades likewise disposed in a parallel configuration.

Associated to the penetrator is an electrically operated clutch for uniting the penetrator with a dial gauge feeler as and when required.

The major-weight-supporting rod is associated to a follower cooperatingwith a test program establishing cam, the lobes on which successively cause: lifting of the lever and the penetrator; lowering of the penetrator alone, and thereafter activation of the minor weight and subsequently the major weight for time lapses determined by the action of a motor and an adjustable timer; and ultimate reverting to the above firstmentioned position whereby to disengage the penetrator after the residual depth of indentation has been read on the dial gauge.

Preferably, the dial gauge driving electric clutch and illumination of the gauge dial are controlled during the operating cycle of the machine.

Triggering means are provided for starting the cycle, which cycle continues until it is terminated by means,

for instance, of contact points rotatably associatedto the cam. I

Further, the machine, as devised above, can readily be equipped with a composite .major weight the constituent elements of which can be rendered operative or inoperative by suitable control means.

The point of the penetrator can be protected inside a movable test specimen thrust surface, which surface can be moved elastically towards an abutment position by the test specimen.

Likewise at this level may be provided electrical contacts for allowing the measurement cycle to be initiated automatically once the test specimen has been positioned beneath the penetrator.

The above-described arrangement makes it possible to achieve considerably improved accuracy in respect of both the component parts of the mechanism and the operation of the cycle, which cycle is fully mechanized and repetitive. In addition,-this increased accuracy is accompaniedby considerably simplified design, which is consistent with significantly improved accuracy.

' BRIEF DESCRIPTIONOF THE DRAWINGS FIG. 4 is a front elevation view of the machine head;

FIG. 5 is a view of the underface of the penetrator protector; and

FIGS. 6 and 7 are schematicillustrations of two alternative embodiments of means for controlling weights usable alternately or jointly as major-weight variators to suit the range of hardness values involved.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, the test mechanism includes a penetrator 1 having a pyramid-shaped diamond point 2, and this penetrator 1 is connected to a pair of nonextensible

flexible blades

3 and 4 of substantial length, arranged parallel to each other and having their penetrator-remote ends restrained at

fixed points

5 and 6. Penetrator l is axially connected to another nonextensible flexible blade 7 capable of working in com: pression, likewise without variation in length, which blade has one end restrained in penetrator 1 and the other in a beam 8 proximate a fulcrum-point 9 thereof adjacent one end of the beam. Fulcrum 9 is formed by two sets of flexible, non-extensible and noncompressible crossed blades restrained respectively on the beam 8 and on fixed points.

Beam 8 carries a positionally adjustable weight 10 adapted to produce a pre-loading of diamond point 2 on the surface of the test specimen. The fulcrumremote free end of beam 8 supports a ring 11 having internal tapering feelers and into which penetrates, with clearance, a hook 12 on the end of a rod 13. Rod 13 is supported and guided by a pair of long flexible but

non-extensible blades

14 and 15 fast at one end with clamps rigid with the rod 13 and restrained at the other end at

fixed points

16 and 17. Rod 13 supports a majorweight-forming plate 18 and its lowermost end remote from hook 12 carries a follower 19 adapted to ride over successive lobes formed on a cam 20 rotated by drive means.

An electromagnet 21 positioned between penetrator 1 and the feeler of a dial gauge 22 is fixed either to the feeler or to the penetrator and, upon being energized, actuates a flexible blade whereby to unite the penetrator and the feeler. Obviously, this flexible blade can be fast with the feeler, if the electromagnet is mounted on the penetrator, or vice versa.

The above-described parts can easily be accommodated in an angled arm 23 forming part of a machine frame, within a column 24 on which arm 23 is cantilevered, and inside a base 25 supporting the column. The base 25 receives a nut 26 carrying hand-operating spokes and into which engages a screw 27 formed with a flat head 28 coaxial with the screw and the penetrator.

Likewise mounted in the base 25 is an electric motor 29 for driving the cam 20, operation of which will be described hereinbelow.

The load forming plate 18 can be associated to other.

weights

30 and 31 for example, which can be raised as required. These weights can be made to rest on plate 18 and to be separated from it responsive to actuation of light individual

flexible ties

32 and 33 attached to a driving drum 34 operated by a knob 35. Knob 35 is mounted on the end of arm 23, opposite a window 36 for reading the dial gauge scale 22. Alongside knob 35 is provided a further knob 37 which allows adjusting a timer for activating the motor 29. The above-described machine is thus provided with a veritable panel of adjustment and reading rneans which facilitate the operators task and insure reliable testing (see FIG. 4).

As shown in FIGS. 2 and 5, the point of penetrator l is protected by a cap 38 consisting of a base and a tapering mouth thereon, the base carrying three adjustable setting bolts 39 arranged to contact the underface of arm 23.-This protective cap is mounted on an elastic diaphragm 40 which is made resilient by flexibilityincreasing stepped arcuate slits. The diaphragm has its periphery secured by screws 41 to spacers beneath the underface of arm 23.

For the purpose of actuating the

ties

32 and 33, drum 34 has a common fastening means to the two ties, the latter being run through separate intermediate eyelets. An eyelet 42 for tie 33 is positioned beneath the pivot of drum 34, and the other eyelet 43 for tie 32 is laterally spaced therefrom. The drum is formed with a series of holes 44 with which a sliding latching peg (not shown) cooperates.

As shown in FIG. 7, as alternative arrangement could be used in conjunction with knob 35, to wit tapering stubs 45 adapted to vary the deflection of a tie, such as tie 32, between a fixed attachment point 46 and an intermediate eyelet 47. The advantage of this arrangement is that it permits operation without latching means, the friction of stub 45 beneath the tie providing sufficient restraint.

Operation of the above-described mechanism is as follows:

An operator places a test specimen on flat head 28, and, by cooperation of nut 26 with screw 27 causes it to be lifted into contact with the end-section of the tapering mouth of the penetrator-protecting cap 38.

Nut 26 can be tightened until the thrust bolts 39 contact the surface of arm 23.

Through the agency of a special starting button (not shown) or of electrical contact points activated when protecting cap 38 abuts against arm 23, the test cycle is initiated with the starting up of motor 29. The highest lobe on cam 20, which through follower 19, rod 13, hook l2 and the upper surface of ring 11 theretofore kept the point of the penetrator inside protecting cap 38, allows follower 19 to descend and to thereby cause the hook 12 to separate from the upper surface of ring 11 as soon as the point of the penetrator is applied against the test specimen. In response to the preloading provided by the weight 10, this application takes place freely and gradually at controlled speed by virtue of the sloping land between the highest lobe on cam 20 and an intermediate lobe thereon. Furthermore, the length of the intermediate lobe determines the controlled time for which the minor load is applied.

At the far end of this intermediate lobe, the follower 19 is caused to descend onto a low lobe on cam 20 that corresponds to hook 12 contacting with the bottom of ring 11 and hence to application of the additional load, provided by the weight of plate 18, to beam 8 and penetrator 1. In this case also, application of the load takes place at controlled speed governed by the profile of the land between the intermediate and low lobes on cam 20.

In this configuration of cam 20 with its low lobe contacting follower 19, a switch operated by actuating means on cam 20 cuts off the electric current to motor 29 and places in circuit the timer set by the position of knob 35. The latter determines the motor shut-off time, and hence the time for which the full load provided by weights l0 and 18 is applied, before it operates once more to activate the motor and fetch a lifting lobe beneath follower 19 that restores the mechanism into its initial position, that is to say with follower 19 on the high cam-lobe beam, 8 supported by hook l2, and penetrator I lifted off the test specimen.

When the timer operates, a lamp for illuminating the dial of gauge 22 is energized to draw the operators attention to the need to take a reading from the instrument.

Further, an electrical contact associated to cam 20 adjacent the downstream end of the intermediate lobe v closes the circuit of the electromagnet 21 which unites penetrator 1 with the feeler of dial gauge 22, this circuit being broken as soon as rotation of cam 20 fetches its final lifting lobe beneath follower 19.

It will thus readily be appreciated that as soon as the measurement cycle is initiated the operator need only vice may be either an independent pushbutton or a contactor associated to protecting cap 38. Further, cap 38 may be formed with a radial slot 48 to provide access to a screw for securing the diamond point to penetrator l.

It should be noted that, whereas in the event of utilization of the

weights

30 and 31, the associated

ties

32 and 33 will be slack, they have only negligible influence on the action of these weights.

On the other hand, the protecting cap 38 performs a useful function since, even if the machine should be operating under no load, the diamond point is not exposed by reason of the mounting 38 on an elastic diaphragm 40. In any event, the bolts 39 permit accurate adjustment-of the position of the diamond point in relation to the test surface to be penetrated.

Clearly, the fact that use is made, for the pivot, for guidance of the beam and the rod, and for transmitting drive between the beam and the penetrator, of nonextensible flexible blades instead of ball-bearings, knife-edges, ball-cages and the like, markedly improves the precision and measuring accuracy of the singlelever mechanism while basically simplifying the construction of the machine.

The same holds true for the use of a single beam instead of two classic levers, as well as for the measurements taken directly off the penetrator.

A very big'improvement, which decisively increases precision and substantially improves efficiency in the case of serially performed hardness tests, stems from full automation of the cycle achieved through the use of a powered cam to fully control the pre-loading and loading apparatus, in conjunction with the use of a timer which sets the time for which 'the full load is applied as well as the approach speeds, thereby making it possible to dispense with the clamping device required in prior art machines.

The electric clutch device between the penetrator and the gauge feeler avoids the traditional preliminary three turns of the pointer on conventional machines and insures that the dialgauge is used only when it is useful and only for a strictly minimum distance travelled.

lt goes without saying that changes and substitutions may be made in the exemplary embodiments described hereinabove without departing from the scope of the invention.

What is claimed is:

1. In a machine for testing the hardness of material by the Rockwell testing method, of the type including, in its frame, a single pivoted lever permanently supporting a minor preloading weight positioned on the same side of the lever fulcrum as means for operatively associating the lever with a penetrator having a point, and having, at its free end, means for attaching it to a major loading weight, the improvement comprising said fulcrum being formed by a pair of crossed first blades secured to said lever and forming an articulation therefor; second and third blades secured at their free ends'respectively to said penetrator and to said major weight, and having fixed ends secured to said frame, said second and third blades respectively guiding said penetrator and said major weight; said means for operatively associating said lever with said penetrator being constituted by a fourth blade secured to said penetrator and engaging said lever; said blades being elastically flexible transversely but non-extensible longitudinally; said crossed first blades constituting the sole means articulating said lever, and said second and third blades constituting the sole means respectively guiding said penetrator and said major weight.

. 2. A machine according to claim 1 in which the major weight is provided with a hook which cooperates, with intermediate clearance, with the tapering inner edges of a coupling ring supported onthe end of said lever.

3. A machine according to claim 2, including powered lifting and lowering means operatively associated with said major weight.

4. A machine according to claim 1, further including a dial gauge having a feeler; and an electrically operated clutch member interposed between said penetrator and said dial gauge feeler and selectively operable to directly couple said penetrator and said dial gauge feeler to each other.

5. A machine according to claim 3, including a motor-rotatated cam, constituting the major weight lifting and lowering means, and having a plurality of lobes thereon providing at least three steps with progressive blending lands therebetween; a plate forming a component of said major load; a rod supporting said plate; a follower on the lower end of said rod engaging said cam; and a controllable motor operable to rotate said cam.

6. A machine according to claim 5, including additional weights selectively usable to form components of said major load; and means, including light, flexible inextensible ties connected to said additional weights and operable to suspend said weights and to deposit the same on said plate. v

7. A machine according to claim 6, including means inside said machine operatively associated with each tie and operable to vary the length of the associated tie; and latching means cooperable with said length varying means.

8. A machine according to claim 5, including a base; an arm; a column connecting said base to said arm; said base containing said cam andits driving motor; said column enclosing said rod and cam follower; said plate positioned substantially at the midpoint of said rod; said arm containing said single lever, said blades, said penetrator, and said minor pre-loading weight; said arm having a head forming a control panel; and a timer setting means, a major-load adjusting means and a dialgauge reading window on said control panel.

9. A machine according to claim 4 including means for signalling the measurement cycle period in the course of the test.

10. A machine according to claim- 3 comprising means for varying the test conditions, including an adjustable timer for rendering the major-weight actuating means inoperative for a predetermined time and means for varying said major weight itself.

11. A machine according to claim 1, including a penetrator point protector elastically mounted on the machine frame and comprising thrust members which limit its movement responsive to approach of the test specimen.

Claims

1. In a machine for testing the hardness of material by the Rockwell testing method, of the type including, in its frame, a single pivoted lever permanently supporting a minor preloading weight positioned on the same side of the lever fulcrum as means for operatively associating the lever with a penetrator having a point, and having, at its free end, means for attaching it to a major loading weight, the improvement comprising said fulcrum being formed by a pair of crossed first blades secured to said lever and forming an articulation therefor; second and third blades secured at their free ends respectively to said penetrator and to said major weight, and having fixed ends secured to said frame, said second and third blades respectively guiding said penetrator and said major weight; said means for operatively associating said lever with said penetrator being constituted by a fourth blade secured to said penetrator and engaging said lever; said blades being elastically flexible transversely but non-extensible longitudinally; said crossed first blades constituting the sole means articulating said lever, and said second and third blades constituting the sole means respectively guiding said penetrator and said major weight.

2. A machine according to claim 1 in which the major weight is provided with a hook which cooperates, with intermediate clearance, with the tapering inner edges of a coupling ring supported on the end of said lever.

6. A machine according to claim 5, including additional weights selectively usable to form components of said major load; and means, including light, flexible inextensible ties connected to said additional weights and operable to suspend said weights and to deposit the same on said plate.

8. A machine according to claim 5, including a base; an arm; a column connecting said base to said arm; said base containing said cam and its driving motor; said column enclosing said rod and cam follower; said plate positioned substantially at the midpoint of said rod; said arm containing said single lever, said blades, said penetrator, and said minor pre-loading weight; saiD arm having a head forming a control panel; and a timer setting means, a major-load adjusting means and a dial-gauge reading window on said control panel.

10. A machine according to claim 3 comprising means for varying the test conditions, including an adjustable timer for rendering the major-weight actuating means inoperative for a predetermined time and means for varying said major weight itself.