US2327139A - Holding means for test specimens - Google Patents

Description

D. c. SCOTT 2,32 7,139

` HOLDING MEANS FOR TEST SPE-CIMEN Aug. 1W'j E943.

Filed DeG. 30, 1942 INVENTOR ATTORNEYS Patented Aug. 127,

U-Ni'1fau` STATE HOLDING MEANS FOR. TEST SPCIIENS David C. Scott, Providence, It. I., assignor to Henry L; Rhode Island Scott Company, a corporation of t Application December30,1942,' Serial No. 470,554

4 claims. (o1. 265-12) This invention relates tothe testing o! flexible' materials such as tapes, webbing, cord or other flexible like materials, the ends of which must be gripped for applying tension thereto inthe performance of the test. A y

In `performing a tensile test upon a flexible material it is diilicult to obtain the proper grip upon the materialso that the samef'will not slip' or become misaligned during the test. It has been proposed to provide twovjawls one of.which is movableand to position an end of the .material to be tested between the jaws and then wrapthe material about the jaws-so that the pull of the.`

material will move one of the jaws toward the other and rmly grip the material Iwhich is located between the jaws. In order that the pull on the material being't'estedmay be free from' the ,material which is wrapped about the fixed jaw differentl expedientshave been resorted to to accomplish this purpose, such for instance as making the fixed jaw smaller than the movable jaw so that the material being tested as it leaves the movable jaw will clear the fixed jaw. This arrangement while satisfactory from the standpoint of clearance does not always position the .25

' line of pull directly through th center line of the specimen able.

One of the objects of the invention is to provide a clamp in which the pulling of thespecimen serves to hold thejaws of the clamp firmly upon the specimen and to properly align thespecimen with reference to the pull thereon.

when under test which is' also desir- Another object of this invention is to so mount the clamp that the line of pull will be directly through the center of the specimen and the' specimen will also leave one of the jaws at such` location as to clear the other jaw and the part of the specimen wrapped thereabout.

Another object of this invention is to providea pair of such jaws between which the specimens extend so mounted that when a pull is applied through the jaws to move the jaws ,directly away v from each other the jaws vwill rock to locate the specimen so4 supported that it will extend along the line of the pull with the pull extending` substantially through the center of the specimen regardless of its thickness. l

Another object of lthe invention is to provide an arrangement for clamping the specimen initially which clamp may be removed as the test proceeds.'

With these and other objects in view, the invention consists ci certain novel features of construction,A as will vbe more fully described and particularly pointed out in the appended claims.

In the accoxripanyingl drawing: 1 y Fig. 1 is a top planview showing the vtest specimen as supported by two of my improved clamps with tension applied to the clamp supports to locate the clamp in the relative position assumed while tension is applied; s

Fig'. 2 is'an elevation of one of the main clamps alone;

' Fig. 3 is an end view of the clamp shown-in Fig. 4 with the auxiliary clamp in place;

Fig. 4-is a central sectional view. oi the clamps shown in Fig. 2 with the auxiliaryl clamp in dotted lines: v

Fig. 5 is a detailed view of the auxiliary clamping means for holding the jaws in initial gripping i position; and

Fig. 6 is anelevation illustratinga machine in which the-clamps are mounted.

The testing machines in which my clamps are used are any of the well-known types of testing machines for testing the tensile strength of textile materials. The horizontal type machine such as illustrated herein may be found in the testingv machine ol Patent No. 1,911,006 dated A May 23, 1933, or No. 2,205,579 dated June 25, 1940,

although it will be appreciated that the arrange- `ment of clamps such as shown herein may be clisv posed vertically if desired.

The test specimen designated I0 is heid at each of its end portions by clamps designated gener ally Il and I2, one of which may be held and the other of which may be moved so as to apply tension on the specimen or both may be movable a load may be applied. The support for one clamp is designated I3 and the support for Athe otherclamp i4 and in the arrangement here shown the Y support l! is moved by some power means such for instance as a thread shaft I5 while the support t3 is held fixed against movement.

The ends of these supports I3 and I4` are threaded as at 20 and the body portion 2| pro- 40 vided with a threaded socket 22 is screwed onto the support I3 or il as may bedeslred. This body is reduced (see Fig. 4) to provide a stud 23 through which a pin 24 extends which is headed and provided with a cleat at one end and is threaded as at 25 at the other end. Member 26 is pivotally mounted upon the stud 23 and is held against escape from the stud by a washer 21 held i snugly against the end of the stud by the nut 28 screwed on to the pin 24'. 4The thickness ofl the collar of the member 2E is less than the length of'the stud so that it has vfreedom oi motion about the stud in a pivotal relation. However,

there extends stops 28 and 3.0 from the body 2| which will be engaged by a pin 3i on the member '2 8 to limit the pivotal movement of the member 26 about the stud 23.

6o tant from the pivotal mounting 23 is halt round 3Gl is slidably guided in this slot whilea .plate 3l attached as at 38 to the underside of the jaw 35 prevents the jaw from being lifted upwardly as seen' in Fig. 4 out of the slot 35. This jaw 35 may move toward the jaw 32 by sliding along the slot 35 which extends in line with the center of the pivot of the studf 23 and the center of the arc of the rounded fixed jaw y33. This movable `jaw also has a rounded surface 33 substantially on the arc of a circle and a fiat surface 39 which is on a diametrical line substantially through the center of the arc of the rounded surface 38. This flat surface 39 is roughened or serrated by means of notches 4I] so as to provide a better holding surface for the end of the specimen which is placed between the jaws to be engaged by the surfaces 34 and 39. -It will'be apparent that the rounded surface 33 is of a smallervradius than the rounded surface 38.

To load the specimen into the device the two clamps are brought sufciently close together so that theV ends of the specimen may be readily fed into each of the clamps. One end of the specimen I which is designated 4I is passed through a slot 42 in the'fixed jaw and there doubled upon itself as as 43 (see Fig. 1). The specimen is then led between the gripping surfaces 34 and 39 as at 44 and then wrapped around the curved surface 33 of the xed jaw as at 45, then about the curved surface 38 of the movable jaw as at 46 (see Fig. 1) and then to the other clamp where a similar disposition of ythe end portion of the specimen to be tested is provided to secure it in position in the companion'clamp. The pull on this specimen is directed along the line of the supports I3 and I4 and the center of the pivots upon which the members l26 of the clamps are mounted are 'in this line of pull thus the center of the studs 23 are in the line of the pull along the supports I3 and I4. As the pull commences the member 26 will rock about the pivots 23 until the specimen I 0 is disposed along the center of pull through the suppoits I3 and I4 and the pivots 23 for the members 26. Thus all of the pull is directed through the center of the specimen. The members 26 rock so' as to provide for this while at the L same time it will be apparent that the specimen l0 leaves the clamp I I at a. tangent directly below the' center of the pivot of the clamp so that the specimen pulls free from contact with any other part of the specimen which is wrapped around `the jaws in order that the directed pull may cause the movable jaw to more firmly pressthis movable jaw toward the fixed jaw without any retarding friction and firmly grip the part of the specimen designated 44 which is between the jaws. By this arrangement a very rm grip on the end portion of the specimen is had and the greater the pull the greater the grip to hold the specimen fixedly in position.

It is apparent, however, that prior to the exerting of some pull upon the specimen it is desirable to clamp the jaws together and accordingly I have provided a pair of arms 45 and 46'with a screw 41 freely rotatable in an opening 48 in the arm 45 and threaded into an opening 49 in the arm 46 by means of an abutment head 50. Another screw 5I has an end 52 abutting the larm 45 while it is threaded through opening 53 in the arm 45. The screw may be moved by reason of a handle 54. This clamp is positioned n the hollow portions and 56 of the jaws and the jaws are initially held together until tension upon the specimen commences then these auxiliary clamps may be removed or may be left in place as desired for the remainder of the test.

I claim:

1. In a testing machine, a clamp support, a member pivotally mounted thereon, a clamp carried by said member at a point spaced from said pivot mounting Aand comprising xed and movable jaws, saidfixed `iaw being distant from said pivotal mounting and the movable jaw being movable toward and from the, fixed jaw whereby the'specimen to be tested may be positioned between the jaws of the clamp and Wrapped about the fixed jaw and then about the movable jaw to extend toward a means to hold the other end so that when tension is applied through the said support the member will rock to dispose the specimen toward the line of pull through said pivotal mounting.

2. In a testing machine, a clamp support, a member pivotally'mounted thereon, a clamp carried by said member at a point spaced from said pivot mounting and comprising xed and movable jaws, said xed jaw beingdistant from said pivotal mounting and ther movable jaw being movable along a line between the fixed jaw-and pivotal mounting toward and from the fixed jaw along a line between the fixed jaw and pivotal mounting whereby the specimen to be tested may be positioned between the jaws of the clamp and wrapped about the fixed jaw and then about the movable jaw to extend toward a means to hold the other end so that when tension is applied through the said support the member will rock to dispose the specirrien toward the line of pull through said pivotal m'ounting.

3. In a testing machine, clamp supports each having a pivot, a member mounted to rock on each of said pivots, and a clamp carried by each of said members at points spaced from said pivots each clamp comprising a half round jaw fixed on the outer end of the member and a half round movable jaw movable toward the fixed jaw whereby the specimen to be tested may be positioned between the jaws of a clamp and wrapped about the xed jaw and then about the movable pull between said pivots.

4. In a testing machine, a clamp support, a member plvotally mounted thereon, a clamp carried by said member at a point spaced from said pivot mounting and comprising fixed and movable jaws, said xed jaw being distant from said pivotal mounting and the movable jaw being movable'toward and from the fixed jaw whereby the specimen to be tested may be positioned between the jaws of theclamp and wrapped about the A:fixedl jaw and then about the movable jaw to extendgtoward a means to hold the other end so that when tension is applied through the said support the member will rock to dispose the' specimen toward the line of pull through said pivotal mounting and means to initially clamp the jaws together upon the specimen.

Y DAVID C. SCOTT.

Images