US2049235A - Apparatus for testing materials by flexure - Google Patents

Description

s. TOUR ET AL TUS FOR TESTING MATERIALS BY FLEXURE APPARA Filed Jan.- 22, 1934 w w W w .a.. w w n m 0 INVENToRs: 0

. positioned in Patented July 28, 1936 APPARATUS FOR TESTING MATERIALS BY FLEXURE Sam Tour, New York, N. Y., and Charles H. Marshall, Short Hills, N. J., assignors to Lucius Pitkin, Inc., New York, N. Y., a corporation of New York Application January 22, 1934, Serial No. 707,710

serves to prevent longitudinal movement of the shaft 5. The shoulder I 'I and said collar I5 are also insulated from said bushing 6 by an insulating washer e.

A clamp I9 is rigidly secured to the front end of said shaft 5, the same having a clamping screw I9 for effecting the clamping of an article to be tested in the desired position in said clamp.

An arcuate scale 20 is marginally secured to the disc I2, the same being ate with the aforesaid pointer I6, and this scale is provided with an integral pointer 2I that is adapted, when the disc I2 rotates, to travel over a second adjustable percentage scale member 22 that is marginally secured to the face 3. Said disc I2 is provided with a plurality of diametrically disposed aptertures 25, which apertures are arranged in pairs, the corresponding apertures of each pair being the same radial distance from the center of the disc. 'I'hese apertures are adapted to receive metal pins of roller members 26, 26 which are identical in Weight with each other and accordingly, adapted to counter-bal ance each other, so that when the pin of roller member 26 is inserted in one of the apertures on one side of the disc and the pin of its counter part 26 is inserted in the corresponding aperture on the other side of the disc, the original center of gravity of said disc will remain unchanged. Said disc I2 is also provided with a series of pins 2l, 2l which are also disposed along the same radius and which pins or either of them, are adapted to receive one or more weights 28.

In order to enable the operative to more accurately determine the bending characteristics 5 Claims.

This invention' relates to the determination of the physical characteristics and more particularly the bending characteristics of various fabricated shapes such as wires, rods and strips, sheets, tubes, bars and the like, whether metallic or non-metallic or whether of elastic or non-resilient material; and has for its particular objects the expeditious testing, with precision, of such materials and the provision, for this purpose of a simple, inexpensive and rugged apparatus. Our invention is fully set forth in the following detailed description with drawing forming a part thereof, in which latter isillustrated an apparatus embodying our invention and adapted for carrying out our improved testing method. Referring to the drawing Figure I is a front elevation of our improved testing apparatus;

Fig. 2 is a central transverse section upon the line 2 2 of Fig. 1;

Fig. 3 is a diagrammatic view of the electric hook up; and

Fig. 4 is a typical graph prepared from the data obtained from a selected specimen of material tested in our improved apparatus.

The reference numeral I designates a metallic shell which is mounted upon a suitable base 2, said shell having apertured front and rear faces 3 and 4 respectively. A metal shaft 5 is substantially centrally mounted in said casing, the same being supported in a bushing 6 which is the aperture a of the rear face. Such shaft is provided with a Worm gear 'l which is splined thereto and meshes with a worm 8 carried on a shaft 8' that is suitably mounted in brackets 9 carried by said rear face 4. Said Worm is adapted to be rotated by a hand crank I that is rigidly secured to the worm shaft 8. The shaft and said gear 'I are electrically insulated from the said bushing 6 by means of insulating sleeve b and insulating washers c that are formed of fiber, hard rubber or the like. A disc I2, having a hollow spindle I3 projecting inwardly therefrom, is mounted on said bushing 6 and preferably ball bearings lli are interposed between said spindle and said bushing in order to reduce to a minimum the friction of rotation of said disc. Said dise is centrally apertured, as indicated by the reference letter d, to permit of the projection therethrough of said shaft 5 and an annular collar I5, carrying a pointer I 6, is frictionally mounted on the inner end or cylindrical shoulder Il of said shaft, which y latter has a peripheral groove I8 thereon adapted to receive the inner end'of a set screw f that such as an electric lamp 29 which is pfeferably mounted near the top of the face 3. The circuit of said lamp is controlled by the switch 30. A battery B serves to supply current to the lamp filament and a shoe 3| electrically connects the clamp I9, via the shaft 5 and gear l, with the said battery. As shown in Fig. 3, the electrical hook-up is such that when the switch is closed, the lamp 29 will be illuminated the instant the free end of the specimen .1: contacts with the stop pin 26, since the current will flow from the .positive terminal of the battery through the face 4 to th-e metal disc I2, to the pin 26, the z, the clamp I9, the shaft 5, the gear 1, the brush 3| and thence to the negative, terminal of the battery.

adapted to co-operswitch 30 to the lamp lament, thence via metal f The method of procedure in order to test the of metal specimens, we provide an indicator,

2 a bending characteristics, as well as to determine the elastic limits of a selected metal specimen in the above described apparatus is as follows:-

A test specimen, such as the metal wire 3:, which must be of a minimum length to at least extend beyond the center of the rst aperture 25 at the right side of the disc I2, is rigidly clamped in the clamp I9 in the position shown in Fig. 1. A weight 28, for example a 100 gram weight is then placed on the pin 21', the axis of said pin being a xed or predetermined distance from the centenof for convenience of calculation say l0 centimeters.

Also the scale 22 is so calibrated that on rotation of the disc I2 any point from zero to the end thereof will read in terms of percentage of gram centimeter capacity or of the total bend--` ing increment applied, such total being the weight on pin 21' multiplied by the distance of the latter from center of disc I2. Since the specimen :c is long enough to extend beyond the second aperture 25 to the right of the disc, which is located l0 centimeters from the axis of the disc I2, the pin 26 is inserted in such second aperture and an identical pin 26 is then inserted in the second aperture from the centeron the left side of the disc in order that such latter pin may, as previously explained, counterbalance the weight of the first pin 26. By means of the crank I0, the disc is now rotated in an anti-clockwise direction until the lowermost edge of the pin 26 just engages the uppermost edge of said test specimen, but without exerting any pressure and at that instant if the switch 30 has been turned to an "ON position, the light 29 will be illuminated, due to the closing of the circuit through the filament thereof. 'The pointer I6, which as stated is mounted on the friction collar I5, is now moved but without changing the position of the disc I2 until it indicates the zero position on the scale 20, and

then the adjustable scale 22 is also adjusted so that the pointer 2l, carried by the former scale 20 indicates the zero posiiton on the latter scale 22.

The test is then proceeded with by turning the crank I0 so as to produce a slight amount of bending of the test specimen :c 'and then, as the disc I2 is slowly rotated, readings are taken from scale 20 indicative of degrees of bending and readings are taken from scale 22 indicative of the load in gram-centimeters, such readings being continued until the desired amount of bending of the specimen has been accomplished and/or the desired amount of load has been applied. Thereupon the load is released by slowly reversing the direction of rotation of the worm, by means of the hand crank I0, and by taking a reading on the scale 20 at the moment the light is extinguished, thus indicating at zero load 'the amount of bending of the specimen cr the amount of the permanent vset of the test specimen thereby obtained. The readings ob-y tained from observing movements of the pointer 2I` across the scale 22 serve to indicate the amount of rotation (anti-clockwise) of the disc I2 (and the consequent amount of displacement cf attached weight 26), such rotation being produced by any pressure, however, slight, exerted by the test specimen against the pin 26 which rotation gradually elevates the weight from the zero position (shown in Fig. 1) to a higher position on the right side of the apparatus until such time as the test specimen takes on a persaid disc, for example the weight 28 will, due lo on the scale can, if desired be plotted in the formV of a graph, such as illustrated in Fig. 4, where- 15 in the vertical readings can be translated into the load in gram-centimeters and the horizontal readingsrepresent the amount of bending in degrees. 'As show by the graph z, which represents a. test conducted on a selected specimen such as the bending proceeds at a substantially uniform rate as the load is steadily increased until a load representing say about 600 gram-centimeters has been applied, after which point the bending increases at a more rapid rate with a slower rate of increase in load, thus indicating that whatever resiliency was originally present in the specimen, has been substantially overcome.

The electric indicator, such as the lamp 29, also serves toindicate whether the test specimen has been deformed after the application of a predetermined load or from a predetermined amount of bending, since if the lamp is extinguished before the pointer I6 is returned to 0 the reading on the scale 20 at the moment the light is extinguished will indicate the amount of permanent deformation which has occurred; whereas if the lamp remains illuminated upon the return of the pointer I6 to 0 it will mean that the test specimen has not been affected bythe predetermined amount of load or amount of bending to which it has been subjected.

The fact that the member 26 constitutes'a roller which is capable of free rotation on the pin on which it is mountedeliminates any tendency for such roller to bind against or cling to the metal specimen during the bending of the latter, withthe consequence that the readingson the respective scales are unaffected. The counterbalancing roller member 26 and its pin are of identical weight with roller 2B and its associated pin but, if desired, a plain pin of such a weight identical with that of roller 26 and its pin 21 may be substituted for thek roller 26' and its pin.

The apparatus is useful for a variety of purposes, for example, in testing a specimen of wire, either springwire or pliable wire, it is desirable that the specimen to be tested be clamped substantiallyas shown in Fig. l and preferably so that its longitudinal axis is substantially coincident with a horizontal diameter extending through the center `of the disc I2, and likewise, that said specimen be so clamped that the righthand vertical edge of the platen or base plate of the clamp, as viewed in Fig. l, passes through the axis of shaft 5. The specimen'so tested should be, when clamped in the central supporting clamp, at least long enough to extend beyond a pin inserted in one of the apertures 25. If the specimen is long enough to admit of the loadapplying pin being inserted in the second aperture to the right of the center of said disc I2, then said aperture-is at a distance of 10 centimeters from the center'of said disc and a 100 gram weight is placed on the pin 21 also located 10 centimeters from the center of the disc, then a reading of 20 on the scale 20 and a reading of 40 on the scale 22, will indicate that the specimen tested had been defiected 20 on the application of a load of 400 gram-centimeters, since the readings on the scale 20 are directly in degrees of bending and the readings on scale 22 are in percentage of gram-centimeter load; in this case 40% of 1000 gram-centimeters. If, however, the pin 26 is located in the rst aperture 25 and such aperture is centimeters distant from the center of the disc then, with the same weight applied to the pin 21', the actual load required to effect the aforesaid amount of 20 of deflection, would be 800 grams at 5 centimeters or again 400 gramcentimeters. Again, if the weight is applied to pin 21 and such pin is located 5 centimeters from the center of the disc, then while the percentage reading indicated on the scale 22 will be the same as when the weight is placd on pin 21' and the same located centimeters from the center of the disc, nevertheless the actual loading figured in gram-centimeters will be one-half.

For measuring the stiffness of very thin or delicate materials, which bend of their own weight when held horizontal the disc I2 may be rotated until pin 21', without any weight applied thereto, is at a definite angular distance from its lowermost position shown in Fig. l and preferably the disc is clamped with a separate individual clamp (not shown) in that position. The clamp I9 is then rotated so that the material to be tested, which is clamped therein, substantially coincides with a vertical, rather than a horizontal axis. The pointer I6 is then set at zero on scale 20 and the specimen rotated by rotating clamp I9 until the specimen contacts with either pin 21 and pin 21' and then the difference between the angular reading on scale 20 and the de nite angle at which disc l2 was clamped will be the amount of bending of the specimen due to its own weight and will be a relative indication of the stiffness of the material. A load may be applied to the lower end of the specimen tested if desired and usually this is preferable where the specimen is so light or flexible that normally it tends to curl when not under load.

For measuring the dynamic stiffness of materials the specimen may be clamped in clamp I9 so that the specimen hangs vertically and just touches the left side of pin 21, the pointer is then set at zero on scale 20, the desired weight 28 is put on pin 21', the disc I2 is rotated by hand to any desired load percentage as indicated on scale 22 and then the disc I2 is suddenly released and allowing the disc I2 to swing in a clockwise direction and allowing pin 21 to strike the specimen thus bending it in a clockwise direction. With the disc I2 then at rest with weight 28 in its lowermost position the specimen is rotated in a counter-clockwise direction by rotating clamp i9 until the specimen again just touches the left side of pin 21. The angular degree of bending of the specimen is then indicated by pointer I6 on scale 20 and this degree of bending is inversely proportional to the dynamic stiffness of the material being tested.

Various changes in the construction of the aforesaid apparatus and in the manner of operating the same from that specifically described herein may be made without departing from the spirit of our invention as embraced within the scope of the appended claims.

Having thus described our invention, what we claim and desire to obtain by United States Patent is:

l. In an apparatus for measuring the bending characteristics of material, the sub-combination comprising a rotatable support adapted to receive a specimen of material to be tested, a rotatable load-applying member mounted on` said support and movable relative thereto and a pointer carried by said support and adapted to rotate therewith but being capable of adjustment relative thereto, a co-operating scale carried by said loadapplying member, a second pointer carried by said load-applying member and a co-operating adjustable scale mounted in proximity to but separate from said load-applying member.

2. In an apparatus for measuring the bending characteristics of material, the sub-combination comprising a rotatable support adapted to receive a specimen of material to be tested, a rotatable load-applying member mounted on said support and movable relative thereto and a pointer carried by said support and adapted to rotate therewith but being capable of adjustment relative thereto, a co-operating scale carried by said loadapplying member, a second pointer carried by said load-applying member, a co-operating adjustable scale mounted in proximity to but separate from said load-applying member and an electric signal adapted to indicate when contact has been made or broken between a test specimen mounted in said support and said loadapplying member.

3. In an apparatus for measuring the bending characteristics of material, the combination comprising a shaft mounting, a shaft journaled therein, a pointer carried by said shaft which normally moves therewith but virtually engages the same so as to be capable of movement, when pressure is applied thereto, peripherally of said shaft, but is incapable of movement longitudinally of said shaft, means for applying a predetermined load to said specimen of material to be tested While effecting rotation thereof, including a disc member through which said shaft projects, such disc being capable of relative movement with respect to said shaft, said disc carrying a scale over which said pointer is adapted to travel during the relative movements of said shaft and disc, means for mounting on said shaft a specimen to be tested and means for rotating said shaft.

4. In an apparatus for measuring the bending characteristics of material, the combination comprising a shaft mounting, a shaft journaled therein, a pointer carried by said shaft which normally moves therewith but virtually engages the same so as to be capable of movement, when pressure is applied thereto, peripherally of said shaft, but is incapable of movement longitudinally of said shaft, means for applying a predetermined load to said specimen of material to be tested while effecting rotation thereof, including a disc member through which said shaft projects, such disc being capable of relative movement with respect to said shaft, said disc carrying a scale over which said pointer is adapted to travel during the relative movements of said shaft and disc, means for mounting on said shaft a specimen to be tested, a second pointer carried by said disc and an adjustable co-operating scale extending marginally of said disc but mounted independently thereof.

5. In an apparatus for measuring the bending characteristics of material, the combination comprising a support for a specimen o! material to be tested, a load-carrying and force-developing member rotatable about said support. removable and adjustable weights on this member, adjustable attachments also mounted on this member for transmitting the desired static or dynamic load or force reaction to a specimen of material mounted in said support and a pointer carried by said support and adapted to rotate therewith but being capable of adjustment relative thereto, a co-operating scale carried by said load-applying member, a second pointer carried by said load-'carrying and force-applying member and a co-operating adjustable scale mounted in proximity to but separate from said load-applying member. v

SAMA TOUR.

CHARLES H. MARSHALL.

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