US2442150A

US2442150A - Control for recording platen in tensile testing machines

Info

Publication number: US2442150A
Application number: US605390A
Authority: US
Inventors: David C Scott
Original assignee: HENRY L SCOTT Co
Current assignee: HENRY L SCOTT Co
Priority date: 1945-07-16
Filing date: 1945-07-16
Publication date: 1948-05-25
Anticipated expiration: 1965-05-25

Description

May 25, 1948. D. 'c. SCOTT 2,442,150

CONTROL FOR RECORDING PLATEN IN TENSILE TESTING MACHINES Filed July 16, 1945 N 2 Sheet s-Sheet 1 INVEN OR fiavj'a co// ATTORNEYS y 1943- D. c. scoTT 2,442,150

CONTROL FOR RECORDING PLATEN IN TENSILE TESTING MACHINES Filed July 16, 1945 2 Sheets-Sheet 2 ,zay.

a V I 6 ATTORNEYS Patented May 25, 1948 UNITED CONTROL FORRECORDING PLATEN IN TENSILE TESTING MACHINES David C. Scott, Providence, R. 1., assignor to Henry Rhode Island L. Scott Company, a corporation of Application July 16, 1945, Serial No. 605,390

7 Claims.

This invention relates to a testing machine of the inclined beam type and more particularly to the control for the platen which is carried by the beam and which records the behavior of the specimen being, tested.

In the use of a testing machine such as shown in my Patent No. 2,205,579 dated June 2 5, 1940, where the beam swings through a relatively great angular are, a slight variation may enter into the movement of the platen relative to the beam by reason of the angular relation assumed by the flexible element which is fixed to the base and extends up to andover a pulley on the beam and thence to the platen.

One of the objects of this invention is to pro-- vide an arrangement so that the platen will move equal amounts relative to the beam for each angular movement of the beam about its pivot.

Another object of the invention is to provide a simple arrangement so that movement of the beam will unwrap aflexible element from a surface which may be shaped to compensate for any irregularity and provide an arrangement so that the let-off of the flexible element will be in the desired proportion to the angular movement of the beam.

With these and other objects in view, the invention consists of certain novel features of con struction, as will be more fully describedand particularly pointed out in the appended claims.

In the accompanying drawings:

Fig. 1 is an elevation of a testing machine equipped with the platen let-off which is the sub- .iect of this invention;

Fig. 2 is a sectional view through the platen illustrating the flexible element attached to the platen with various other parts of the mechanism removed;

Fig. 3 is a plan view of the cam surface diagrammatically showing its arrangement relative to the pivot of the bea Fig. 4 is an edge view of the cam;

Fig. 5 is a fragmental view showing the uniform graph of the chart used;

Fig. 6 is a rear view of the testing machine shown in Fig. 1;

Fig. '1 is a sectional view through the platen with a modified form of drum;

Fig. 8 illustrates an eccentrically mounted drum of Fi '7;

Fig. 9 is an edge view thereof;

Fig. 10 is a fragmental view illustrating the error which may occur in a machine of the type illustrated in the above-mentioned patent.

In proceeding with this invention 1' have pro-i;

vided a cam. surface along which the flexible elementwhich controls the platen extends. This surface is such that-"as the beam tilts the flexible element will be made available in. amounts to control the descent of the platen in its guided path. The shape of the surface is such that equal amounts of let-off are provided for equal amounts of angular movement of the beam on its pivot.

With reference to the drawings 10 designates the base of the machine with a standard ll projecting upwardly therefrom. A beam designated generally I2 is pivoted on shaft l3 so that it may rock relative to the standard H. The beam will be lowered through a fixed leg l4 provided thereon, which leg has rollers l5 and i6 engaging a yoke I! on the rack bar l8 which engages with a pinion in a gear box IS, the gears therein being driven through a motor 20 and belt 2! and controlled by a lever 2-2 having handle 23.

A clamp 24 is carried by the beam in order that a specimen 25 may be fixed.- thereto. A clamp 26 engages the other end of the specimen and is carried by a movable weight carriage 21 having wheels 28 to engage a track 29 on the beam and be moved by gravity in response to the tilting of the beam about the pivot 13. A bumper 30 mounted at 3| on the other end of the beam is provided to catch and cushion the carriage should it move suddenly after the break of a specimen.

Anti-friction roller

32, 33, 34, 35 are grooved to slidingly mount a platen 36 having a clamp 31 thereon for the gripping of chart 38 which is to be marked upon by an instrument 3-9 carried by rod 40 attached to the carriage. This platen 36 will move by gravity at right angles to the beam.

In order to control the movement of the platen I provide shaft 4| mounted on the roller frame in the back of the platen. A drum 42 is fixed on this shaft M and has a flexible element 43 fixed to the drum and coiled about it and extending to the lower edge of the platen as at 44 (see Fig. l or Fig. 6). Thus, as the shaft turns the drum will wind up or let off the flexible element 43. A drum 4'5 also secured to the shaft 41 and a flexible element 46 is attached to this drum and coiled about it. flexible element extends along a slightly grooved surface 4''! which is in. the shape of a cam 48, the surface being eccentric to the pivot l3 about which the beam 12 swings. This cam is supported by an arm 48' which is fixed with reference to the frame of the machine. As the beam swings to the left in the position illustrated by Fig. 6, the flexible element '06 is unwrapped from the cam 48 thus permitting gravity to move the platen downwardly to wrap this element 46 about the drum 45 as the platen descends. The amount the platen descends or moves with reference to the beam will be controlled by the amount of let-off from this surface and accordingly I may control the amount of let-off by the shape of the surface 48 so that the let-off will be proportional to the angular swing of the beam about its pivot.

This cam surface 48 as shown in Fig. 3 is substantially on the arc of a circle but assuming that the pivot is at l3, see Fig. 3, I then move the center of this circle of radius 49 to a location 50 which in the case of an are having a ten inch radius will be moved to the right an inch and a half and downwardly an inch and a half as one example of eccentricity which I have found to provide a correct relationship of cam surface to the arcuate swing in a machine substantially of the proportion here illustrated.

In Fig. 8 I have illustrated the drum on the shaft 4| as eccentrically arranged which may be an optional means of controlling the platen in the correct amount. In this case a truly concentric surface for the cam 48 with reference to the pivot l3 will be provided.

In Fig. 10 I have illustrated a diagrammatic view showing at angle 10 the variation from a straight line which will occur during movement of a beam with a flexible element arranged as shown in Patent No. 2,205,579. The dot-dash line will be somewhat longer than a vertical from the point H to the base 12, which would be the true distance desired if the amount of let-off was to be directly proportional to the angular relation of the beam.

I claim:

1. In atesting machine, a support, an inclinable beam mounted on said support, a platen carried by said beam, said platen being movable relative to said beam and laterally thereof by gravity when unrestrained, a member fixed relative to said support, a rotatable member mounted on said beam and movable therewith toward said fixed member, means secured to said platen and operatively connected to said rotatable member to restrain the movement of the platen, a flexible element extending between said members and secured thereto controlling the rotation of said rotatable member, and eccentric means carried by one of said members and engaging said element and operable upon the tilting of the beam to control the length of said'element between said members to cause movement of the platen relative to the beam directly proportional to the angular are through which the beam moves.

2. A testing machine as set forth in claim 1 wherein said eccentric means comprises a surface from which said flexible element is unwrapped, the shape of said surface determining the relative movement of said platen and said surface being fixed.

3. In a testing machine, a support, an inclinable beam pivotally mounted on said support, a platen carried by said beam, said platen being movable relative to said beam and laterally thereof by gravity when unrestrained, a member fixed relative to said support and having a cam surface thereon, a rotatable member mounted on. said beam and movable therewith toward said fixed member, means secured to said platen and operatively connected to said rotatable member to restrain the movement of the platen, and a flexible element extending between said members and over said cam surface for controlling the rotation of said rotatable member whereby upon the tilting of the beam the flexible element is unwrapped from said cam surface to cause movement of the platen relative to the beam directly proportional to the angular arc through which the beam moves.

4. A testing machine, as set forth in claim 3, wherein said cam surface is substantially on the arc of a circle,

5. A testing machine as set forth in claim 4, wherein the center of the arc of the circle is positioned closely adjacent and spaced from the pivoted mounting of the beam.

6. In a testing machine, a support, an inclinable beam pivotally mounted on said support, a platen carried by said beam, said platen being movable relative to said beam and laterally thereof by gravity when unrestrained, an arm extending generally toward said platen and fixed relative to said support, a drum carried by said beam and movable therewith toward said arm, means secured to said platen and operatively connected to said rotatable member to restrain the movement of the platen, said arm having a curved surface extending in the general direction of the arc of movement of the beam, and a flexible element extending between said drum and said arm and over said curved surface for controlling the rotation of said drum whereby upon the tilting of the beam the flexible element is unwrapped from said curved surface to cause movement of the platen relative to the beam directly proportional to the angular are through which the beam moves.

7. In a testing machine having an inclinable beam movable on the arc of a circle and a platen carried by said beam and movable relative thereto laterally thereof by gravity when unrestrained, means to cause movement of the platen relative to the beam directly proportional to the angular are through which the beam moves, said means including a support having a surface fixed thereto and extending in the arc of a circle and positioned to be eccentric with the arc of movement of said beam and flexible means engaging said eccentric surface and operatively connected to said platen and through which the movement of the platen is restrained, said flexible means being unwrapped from said surface as the beam moves on an are about its pivot.

DAVID C. SCOTT.

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

UNITED STATES PATENTS Number Name Date 2,205,579 Scott June 25, 1940 2,286,651 Scott June 16, 1942