US2557449A - Endurance testing machine - Google Patents

Description

June 19, 1951 1-. MELVILLE ENDURANCE TESTING MACHINE 4 Sheets-Sheet 1 Filed Jan. 2, 1947 FIG. 1- zal A June 19, 1951 'r. MELVILLE 2,557,449

ENDURANCE TESTING MACHINE Filed Jan. 2, 1947 4 Sheets-Sheet 2 FIGS- i'j w w //i w June 19, 1951 'r. MELVILLE 2,557,449

ENDURANCE TESTING MACHINE Filed Jan. 2 1947 4 Sheets-Sheet 5 FIG. 5- FIG. 7.

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June 19, 1951 T. MELVILLE ENDURANCE TESTING MACHINE 4 Sheets-Sheet 4 Filed Jan. 2, 1947 11206 72307: 7/Z/0M45 May/11E, 44 ,omzufipzabn Patented June 19, 1951 UNITED STATES PATENT OFFICE ENDURANCE TESTING MACHINE Thomas Melville, Cleveland, Ohio Application January 2, 1947, Serial No. 719,739

Claims. (01. 73-91) This invention relates to a novel method and apparatus for testing the endurance properties of wire rope, cables and the like.

As will appear more fully hereinafter, the novel method involves looping a specimen of rope around a plurality of sheaves journaled on a rotary member and applying a load of predetermined magnitude to the specimen while turning the rotary member through a predetermined number of revolutions, thus subjecting the speciment to a definite number of bendings or flexure stresses, releasing the load from the specimen and disengaging it from the sheaves and finally, either applying to the specimen a tensile stress of a magnitude to determine its safe working strength, or counting the number of strands broken by said predetermined number of bendmgs.

For a more complete disclosure of all aspects of the invention, reference should be made to the following specification, the accompanying drawings and the appended claims.

In the drawings:

Figure 1 is a plan view of novel apparatus especially designed for carrying out the herein claimed method.

Figure 2 is a front elevation of the apparatus of Figure 1.

Figure 3 is an end elevation viewed from right of Figure 2.

Figure 4 is a fragmentary detail view illustrating a modification.

Figure 5 is a section on line 5-5 of Figure 4.

Figures 6, 7 and 8 are diagrams illustrating different positions of the apparatus of Figures 4 and 5.

Figure 9 is a detail view illustrating modified means for applying the load to a test specimen.

Figure 10 is a view illustrating a further modification.

Figure 11 is a sectional view showing the application of the invention to the testing of rope or cable in a corrosive atmosphere.

Figure 12 is a diagram illustrating a further modification.

the

Figure 13 is a perspective view of a modifica tion of the apparatus to adapt the machine for the simultaneous testing of a multiplicity of specimens.

Referring in detail to the drawings, reference numeral Ill represents a base plate supported on a suitable standard as shown. The base plate has secured thereto bearings l2l2 rotatably supporting a shaft I l carrying a grooved pulley I6 adapted to be connected by a v-belt l8 with a portions secured to the underside of the base 26,

, the screw being turned by a suitable hand Wheel 32. Alternatively, variations in the speed rotation of the shaft M can be effected by use of any conventional type of variable speed motor.

The shaft I4 has keyed or otherwise secured thereto a disc 34 carrying a plurality of equidistantly spaced and circularly arranged studs 36 which serve as respective journals for a plurality of grooved sheaves 38. In the machine illus trated, four sheaves 38 are journalled on the rotary disc, these being spaced apart and all rotating on a respective journal stud spaced the. same radial distance from the axis of rotation o" the shaft l4. More or less than four sheaves 38 may be used, for example, three sheaves spaced apart may be employed or five, six, or eight sheaves may be spaced respectively 72, 60, or

45 apart. The greater the number of sheaves employed the less will be each individual bending action and conversely, the fewer sheaves used the greater will be the bending action on the test specimen.

A revolution counter 48 is connected by a conventional form of self-aligning coupling 42 to one end of the shaft 14. This counter includes a known form of mechanism diagrammatically indicated at 44 which is efiective to operate a switch 46 so as to open the circuit of a relay 48 for the express purpose of stopping the motor 24 after a predetermined number of revolutions have been imparted to the shaft M and disc 34 which moves in unison therewith. As thus arranged, it is manifest that the counter 40 may be set to interrupt the circuit of the motor 24 after the test specimen reeved around the sheaves 38 has been subjected to a predetermined number of bending stresses. From the drawings, it will be understood that in order to test the endurance ,prop erties of a specimen of rope, cable, cord or the like, a short length of such material may be severed from the supply reel or coil of rope to be tested. Such a specimen is indicated at 50 in Figure 2. Respective loops 52 are formed in each end of the specimen by means of suitable clamp tically adjusted by a screw 86 having a thumb wheel 68 secured thereto, the screw being provided with fixed collars and being rotatable in fixed lugs 18. The loading beam 68 carries a spirit level I2 for convenience in positioning the beam in a truly horizontal position. Slidably mounted on the loading beam there is a weight I4 carrying a set screw I6. As thus arranged, it will be appreciated that by shifting the weight I4 along the beam 68 the magnitude of the force exerted on the test specimen may be varied.

The mechanism described is adapted to stop the motor 24 after the test specimen has been subjected to a predetermined numberof bendings. And in some cases, I also contemplate the provision of means for automatically stopping the motor 24 after the test specimen has been stretched beyond a predetermined amount. As shown diagrammatically in Figure 2, the means for automatically stopping the motor upon the determined stretch of the specimen may take the form of a relay switch which will be operated by a finger II on the extreme end of the beam 68 so as to close the circuit of a battery I8 to energize a magnet 88 which will open a switch 82 which normally closes the motor circuit across the contacts 84.

The degree of stressing to which the specimen 58 under test is subjected is dependent upon three variable factors namely, the number of sheaves 38 around which the specimen has reeved, the diameter of the sheaves 38, and the load imposed on the specimen as controlled by the weight I4 or its position on the beam 68. By a different combination of these variables (number of sheaves, diameter of sheaves and load applied) the conditions which the rope or cable under test is adapted to withstand in practice can be readily simulated. To simulate the normal working conditions of rope or cable performance, I consider it desirable to incorporate in the testing apparatus a vibration dampening means. For this reason in the embodiment of the invention, shown in Figure 2, I interpose a vibration dampening spring 86 between the base 88 of the yoke and member 98 on the underside of the beam 68. The use of such vibration dampening means also prevents chattering of the testing machine as the disc 38 rotates at a high speed and also ,contributes to smoothness in the entire testing operation.

In carrying out a test in accordance with my herein claimed method, after the specimen has been subjected to the desired number of bendings, the load will be removed from the specimen and the specimen unreeved from the sheaves 38, whereupon the loops 52 will be disengaged from the anchorages 56 and the ends of the test specimen will be engaged with the members of a conventional form of tensile strength, testing machine. Suflicient load will be exerted by this machine to strain the specimen to a degree suflicient to cause a permanent set to take place which will usually occur after the elastic limit has been exceeded or of suflicient magnitude to rupture the specimen. In other words, after the predetermined number of bending stresses have been imposed on the specimen, it will be tested in a conventional testing machine in order to evaluate its strength characteristics. Instead of such tensile stretching of the specimen in some cases I contemplate merely counting the number of strands which have been broken after the specimen has been subjected to a predetermined number of bendings by the action of the rotation of the disc 84 in order to evaluate the endurance properties of the specimen.

It is well known that on installations where a rope or cable passes over a sheave that it is important that the sheave be located so as to maintain a small fleet angle at all times. By fleet angle is meant the side angle at which the rope or cable approaches the sheave. It is the angle between the median plane of the sheave groove, as viewed edgewise, and the longitudinal axis or center line of the rope or cable. In order to carry out a test on the endurance testing machine of the invention to determine the efl'ect of fleet angle on a wire rope passing over a sheave, spacers, not shown, may be mounted on the studs 36 between the grooved sheaves 38 and the disc 34 so as to produce a predetermined angle between the rope or cable and a plane passing through the groove of the sheave perpendicular to the rotating axis of the same. With such an arrangement of the apparatus, the method for determining the endurance properties of the rope at various given fleet angles may be readily carried out.

Figures 4 to 8, inclusive, illustrate means whereby the driving motor for the testing machine may be automatically stopped upon breakage of one or more strands of the test specimen. Referring to these figures, the disc 34 carries a bale-like member 92 which straddles the flats of a hexagonal nut 94 secured to the end of the shaft I4. The member 92 has a shallow recess It formed therein to accommodate the end of a shut-off arm 98 pivoted on a screw stud I88 which carries a washer I82 between which, and the end of the arm 88, there is interposed a spring I84.

The arm 98 is slotted at I86 to adjustably accommodate a stud I88 carrying a wing nut I I8, thus forming an adjustable journal for a circular pad N2 of felt or similar fibrous material mounted between two washers I I4 on the stud I88.

Near its outer end, the arm 98 has rotatably journaled therein a wheel IIG which rides on the periphery of the diSc 34. This wheel carries a radially extending pin III which when turned through an angle at approximately 90 will occupy the position shown diagrammatically in Figure 7. When in this outward position, the pin II8 enters a notch I28 formed in the outer extremity of the arm 98. With the pin III in the extended position of Figure 'I, after further rotation of the disc 34*, said pin H8 is adapted to strike an arm 8 of a microswitch such as indicated at I22 in Figures 6 to 8. This switch, when closed by being engaged by the pin III, is efieetive to out 0115 the power current to the driving motor 24. The mechanism as described only comes into operative position upon the breakage of one or more strands of the test specimen. When such breakage occurs, the broken strand will snare the felt, fibrous material of the circular pad I I2 and will impart suillcient angular movement to the arm 98 to swing the pin I I8 from the position of Figures 4 to 6 to the position of Figure 7, thus continued rotation of the disc 34* will shift the pin I I8 into position for coaction of the microswitch as described, thus automatically stopping the motor of the testing device upon the breakage of one or more strands in the test specimen.

In a modification of Figure 9, I have shown a test specimen '50, the ends 52 of which are engaged with a hook 56 of a rod 58 carrying a plurality of weights 16, the lower one of which bears on a vibration absorbing compression spring 86, whose lower end rests on a washer 88 hearing on a nut 88 screwed to the lower extremity of a rod 58. It will be understood that the principle of operation of this embodiment of the invention, insofar as the vibration absorption is concerned, is much the same as that shown in Figure 2 and that the magnitude'of stress exerted can be readily varied by changing the weights I6 In a modification of Figure 10 I have illustrated a loading beam 60 pivoted at 62 carrying an adjustable weight 14 In this modification the test specimen is secured at 5|) to a vibration dampening spring 86*, one end of which is secured to an end of the test specimen, the other end of which is anchored at 86 to the beam 60. The dead end of the specimen is secured to the hooked portion .ill of a fixed anchorage rod 50 secured to the base or any other fixed support.

In Figure 11, I have diagrammatically illustrated means for testing rope specimens or the like in a corrosive atmosphere. Such tests will be carried out by reeving the rope specimen around sheaves 38 of a disc 34 located in a substantially gas-tight casing such as indicated at I30. One end of the test specimen will be secured to a fixed anchorage 50 within the casing. The other end portion will pass around a guide sheave I32 within the casing and will connect with an exterior vibration dampening spring 86 whose opposite end is connected to a beam Go The motion will be transmitted to the rotary disc 34 within the casing by means of suitable bevelled gearing I34 powered by a shaft I35 connected with a suitable drive motor whose power circuit may be controlled as hereinabove described.

Figure 12 diagrammatically illustrates a modification employing means for imparting an oscillation to the test specimen. In this modification, the disc 34 will carry a plurality of sheaves 38 around which the specimen 50 to be tested is reeved. A load l4 is secured to one end of the test specimen and its other end is secured to an oscillating disc I36 secured to a rock shaft I38 which is adapted to be oscillated by means of a pitman I39 whose ends I40 and I42 respectively are secured to studs mounted in the member I 36 and in a rotating member I44 which may be regarded as a gear meshing with a gear carried by the shaft supporting the disc 34.

Figure 13 diagrammatically illustrates means whereby a multiplicity of test specimens may be simultaneously tested. As shown in this figure there are a plurality of rotatable discs 34 each carrying on its opposite faces a plurality of sheaves 38 around which are reeved the specimens to be tested. One end of each specimen is dead ended for example, by being fastened to eye-anchorages I48. The opposite ends of the specimens are secured to vibration dampening springs 86 which are secured to eye-members I48 carried by beams I50 pivoted on a fixed crossrod I52, each beam having adjustably mounted thereon a loading member I54 as shown. With the parts as shown in this modification, the discs 34 are so constructed and arranged so as to have a free-wheeling mounting on the supporting shaft by interposing a free-wheeling clutch between each disc and shaft. With such an arrangement one or more discs 34 can be permitted to be operating'while others are at a standstill. The use of the clutches would greatly facilitate obtaining a typical number of cycles vs. breaking load curve, such as is frequently used in comparing strength characteristics of different ropes or cables.

In the various embodiments of the invention illustrated, it will be understood that one or more test specimens are adapted to be subjected to a multiplicity of bendings resulting from the rotation of the sheaves 38 through a circular orbit. In their travel through. the circular orbit the sheaves ride through the bight of the test specimen, thus all portions of the bight will be repeatedly subjected to a predetermined number of bendings or fiexings. In this way the endurance qualities of various sizes and types of rope,

cables, cords and the like can be readily evaluated.

In the use of rope or cable for various purposes, it is frequently desirable to employ a particular diameter of sheave bearing a definite rela- 'tionship to the rope or cable to be reeved thereover. The herein described apparatus lends itself to the testing of the proper size sheaves for use with given cables and the sheaves to be tested may be mounted at the locations indicated for the sheaves 38 and 38 hereinabove described.

The drawings and detailed description above are to be construed in an illustrative rather than a limiting sense, since various modifications and substitutions of equivalents may be made by those skilled in the art without departure from the invention as defined in the appended claims. The described apparatus may also be used for testing the comparative desirability of sheave bearings constructed of various suitable materials which may be either metallic or non-metallic for use with given cables and sheaves, the hearings to be tested being mounted at the same locations indicated for the sheaves.

I claim:

1. A machine for testing the endurance properties of wire rope comprising a frame structure, a disc rotatably mounted on said frame structure, motive means for driving said disc, a plurality of circumferentially grooved sheaves mounted on a face of said disc for free rotation and adapted to have a wire rope test specimen reeved therearound, an arm fulcrumed to said frame structure beneath said disc, an attachment device carried by said arm adapted to fix the free ends of the test specimen, and an adjustable weight carried by said arm beyond said attachment device for tensioning the test specimen.

2. A machine for testing the endurance properties of wire rope comprising a frame structure, a disc rotatably mounted on said frame structure, motive means for driving said disc, a plurality of circumferentially grooved sheaves mounted on a face of said disc for free rotation and adapted to have a wire rope test specimen reeved therearound, a bearing carried by said frame structure below and to one side of the disc axis and being adjustable toward and away from said disc, an arm fulcrumed to said bearing and extending beneath said disc, a yoke carried by said arm and provided with attachment means adapted to fix the free ends of the test specimen, vibration dampening means between said yoke and said arm, an adjustable weight carried by said arm beyond said yoke for tensioning the test specimen, and means for auto-'- matically stopping said motive means after a test has progressed beyond a predetermined point.

3. A machine for testing the endurance properties of wire rope comprising a frame structure, a disc rotatably mounted on said frame structure, motive means for driving said disc, a plurality of circumferentially grooved sheaves mounted on a face of said disc for free rotation and adapted to have a wire rope test specimen reeved therearound, a bearing carried by said frame structure below and to one side of the disc axis and being adjustable toward and away from said disc, an arm fulcrumed to said bearing and extending beneath said disc, a yoke carried by said arm and provided with attachment means adapted to fix the free ends of the test specimen, vibration dampening means between said yoke and said am, an adjustable weight carried by said arm beyond said yoke for tensioning the test specimen, and an electric switch engageable by said am after elongation of the test specimen by a predetermined length for automatically stopping said motive means.

4. A machine for testing the endurance properties of wire rope comprising a frame structure,

a disc rotatably mounted on said frame struc-' ture, motive means for driving said disc, a plurality of circumferentially grooved sheaves mounted on a face of said disc for free rotation and adapted to have a wire rope test specimen reeved therearound, an arm fulcrumed to said frame structure beneath said disc, an attachment device carried by said arm adapted to 11:: the free ends of the test specimen, an adjustable weight carried by said arm beyond said attachment device for tensioning the test speciof the anchored ends of the specimen, and turning the rotary member so as to subject the specimen to repeated bending stresses in at least two different planes.

THOMAS MELVILIE.

REFERENCES CITED The following references are of record in the file oi. this patent:

UNITED STATES PATENTS Number Name Date 889,993 Vaughn et al. June 9, 1908 1,062,595 Kapp May 27, 1913 1,875,439 Gerstenslager Sept. 6, 1932 1,913,502 Millward June 13, 1933 1,938,282 Zapf Nov. 21, 1933 1,954,483 Krall Apr. 10, 1934 1,987,787 Miller Jan. 15, 1935 2,170,640 Kenyon Aug. 22, 1939 2,291,086 Lessig July 28, 1942 FOREIGN PATENTS Number Country Date 225,087 GreatBritain Nov. 27, 1924

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