US2843390A

US2843390A - Fluid operated testing machines

Info

Publication number: US2843390A
Application number: US477175A
Authority: US
Inventors: Francis C Huyser
Original assignee: American Machine and Metals Inc
Current assignee: American Machine and Metals Inc
Priority date: 1954-12-23
Filing date: 1954-12-23
Publication date: 1958-07-15
Anticipated expiration: 1975-07-15

Description

F. CfHUYSER FLUID OPERATED TESTING MACHINES Filed Dec. 23, 1954 2 Sheets-Sheet 1 w mun INVENTOR Evan/c4: Obi/n5 BY m mzm ATTO R N EY July 15, 1958 F. c. HUYSER FLUID OPERATED TESTING MACHINES Filed Dec. 23, 1954 2 Sheets-Sheet 2 Aw Q 31 25 27 I F mvus gag 124 /4 K BY Xlw/MQnxPW ATTORNEYS 2,843,390 Patented July 15, 1958 fitice FLUID OPERATED TESTING MACHINES Francis C. Huyser, Moline, Ill., assignor to American Machine and Metals, Inc., New York, N. Y., a corporation of Delaware This invention relates to grips or chucks for specimen testing machines and particularly to power operated grip means for use in torsion testing machines and the like.

One of the problems in testing machines wherein a test specimen is twisted about its longitudinal axis is to grip the specimen so that it will be held firmly from turning in the grip regardless of direction of torque or dwell in movement thereof. Many prior gripping devices have been mechanically operated which do not provide sufficient gripping force, and some have had a wedgeshaped arrangement so that the devices will tighten when force is exerted on the piece in one direction, but tend to loosen when force is in the other direction.

One of the objects of this invention is to provide a grip or chuck capable of exerting high holding force between its specimen holding members, said force not being affected by the direction in which the torque is exerted on the specimen by the head or grip.

In one aspect of the invention, the gripping head may have jaw means movable inwardly relative to each other or toward a specimen, and may have fluid pressure motor means connected therewith for completing the tightening movement of the jaw means relative to said specimen. Sufiicient force can be exerted by a fluid motor to an extent not possible with mechanical moving mechanisms, which insures that the jaw means will grip the specimen with sufficient force to hold the same. Position locking means, such as a means movable between said jaw means and the head, can be provided to lock or locate the jaw means in tight specimen gripping position after operation of the pressure motor means.

In a preferred form, position locking nuts are screw threadedly mounted on the jaw means or means connecting the motor means and said jaw means, the nuts cooperating with an abutting face means on the head. The nuts may have teeth on their exterior engageable by teeth located upon a shaft means, or by gear means so that when the shaft means is turned, the nuts will be appropriately rotated to lock the jaw means in position. The nuts can be rotated to bring the jaw means initially into contact with the specimen, such serving to properly synchronize the jaws. Fluid pressure then can be applied to the motor means to provide the required force to engage properly the specimen. The nuts then can be turned further to lock the jaw means in tight specimen gri ping position. The nut means also could be mounted on the head and the fixed abutment carried by the jaw means or means moving the same. It is particularly of importance that the jaw means engage the specimen in a torsion testing machine with suflicient force to prevent slippage of the specimen as torque is applied thereto.

Other objects, features and advantages of this invention will be apparent from the following detailed description and the accompanying drawings of illustrative embodiments of the invention, which are merely exemplary.

In the drawings:

Fig. 1 is a side elevational view of a torsion testing machine in which the grip means can be employed;

Fig. 2 is an enlarged front view of one of the gripping heads;

Fig. 3 is a cross section along line 3--3 of Fig. 2;

Fig. 4 is a cross section along line 4-4 of Fig. 2; and

Fig. 5 is an enlarged fragmentary front view of a portion of the grip, partly in section.

An example of one use of the invention is seen in Fig. 1 wherein a torsion testing machine can have gripping heads 11 and 12 for gripping test specimen 13, it being understood that the invention is capable of being used in other types of machines of this general nature, and is not limited to a torsion testing machine.

In the illustrated torsion testing machine, gripping head 11 is rotatably mounted upon indicating unit 14, said unit having the usual indicating dial 15 together with a conventional stress-strain recording unit if desired. Gripping head 11 can be arranged to transmit the load exerted upon the specimen through a knife-edged lever system to a pendulum load indicator, the applied load being automatically balanced against the corresponding displacement of a weighted pendulum. Indicating unit 14 can be moved along track means 16 so that specimens of different lengths can be accommodated between the gripping heads. It should be evident that either head could be so constructed as to be moved .relative to the other and to the base of the machine.

Twisting head 12 can be carried upon the loading unit 17 and turned by any suitable mechanism such as a positive infinitely variable speed drive.

Each of the gripping heads may have jaws 18 and 19 (Figs. 2, 3, 5) movable toward each other so as to grip a test specimen therebetween, said jaws preferably being V-shaped so as to grip a specimen on either side of a radial center line through the bottom of the notch of the jaws.

Cylindrical members

20 and 21, carrying the jaw moving mechanism, are mounted in opposed relationship upon base member 22, fluid connections 32, 33 being provided for

cylindrical members

20, 21, respectively. A suitable fluid pressure supply system can. be connected to pipes 32, 33, and by way of example, 50 to 60 tons of pressure or force can be employed.

The details of the jaw actuating mechanism for jaw 19 will be described, jaw 18 also having a similar arrangement, identical numerals being used where appropriate. Jaw 19 is movable inwardly and preferably radially by subjecting piston 28 (Figs. 3 and 5) to fluid pressure, through pipe connection 33, the force being exerted through shank 23 and jaw holder 24 to the jaw. Jaw holder 24 has jaw retaining plates 25 fastened to the holder 24- by screws 26. The jaw holders are held in a recess in the head and guided in their movement by guide plates 27. In the form shown, piston 28, shank 23 and jaw holder 24 are separable, projections 29 and 30 being receivable in suitable apertures in the adjacent parts. The piston 28, shank 23 and jaw holder 24, of course, can be of unitary construction. Packing 34 can be located between piston element 28 and shank 23, an O-ring or suitable packing 35 being located in a groove in said shank.

Guide bushing 36 can be removably secured to the open end of cylindrical member 21, said bushing serving as a stop face or abutment for adjustable position locking nut or means 37. Position locking nut 3'7 has internal threads engaging threads 38 on shank 23.

Position locking nut operating shaft 39 is rotatably mounted in a bore 40 in base 22, there being suitable bearings and means therein for locating and holding said shaft. Shaft 39 has elongated gear teeth 41 thereon extending axially a suflicient distance to provide for the required travel of locking nuts 37 therealong. Turning of shaft 39 in the proper direction by rotating projecting squared shank 42 thereof will appropriately rotate nuts 3 37 and cause

jaws

18 and 19 to move toward each other, guide bushing 36 receiving the thrust exerted by the nuts.

As an example of operation of the device, a specimen to be tested can be inserted between

jaws

18, 19 and shaft 39 is rotated until the rotation of the nuts causes the

jaws

18 and 19 to contact the specimen. Fluid pressure then can be exerted through connections 32 and 33 on the respective opposing pistons to force the jaws into tight engagement with the specimen. This will result in the nuts 37 moving inwardly and becoming spaced from their respective bushings 36. Shaft 39 then is rotated further to bring the position locking nuts tightly against the faces of their respective bushings 36 to lock or positively position the jaws in their tight specimen gripping condition. Thus, it is seen that the proper bite on the specimen is obtained hydraulically and that the parts then are locked with the jaws in their extended or specimen gripping condition.

It is to be understood that the arrangement herein can be used for other purposes and that details ofconstruction can be varied without departing from the spirit of the invention exceptas defined in the appended claims.

What is claimed is:

1. In an article gripping device, the combination including jaw means movable radially on a base to engage an article, power operated means connected to said jaw means for exerting a large force on said jaw means to tightly engage the article, and movable position locking means between said jaw means and base, operable to lock said jaw means against movement in releasing direction when said jaw means is extended and tightly engaging the article.

2. In a testing machine specimen gripping device, the combination including a gripping head, a pair of jaw means movable relatively toward and away from each other on said head, power operated means connected to each jaw means, position locking means adjustably mounted between each of said jaw means and said head, and means moving said locking means to hold said jaw means in the inwardly extended specimen holding position when said jaw means have been so moved by said power operated means.

3. In a testing machine specimen gripping device, the combination including a gripping head, a pair of jaw means movable relatively toward and away from each other on said head, power operated means connected to each jaw means, position locking means adjustably mounted between each of said jaw means and said head, said position locking means being arranged to move said '4 jaw means toward each other to efiect an initial gripping of a specimen, said power operated means being effective to move said jaws means into a final tightened position in which said specimen is held with great force, and means to move said position locking means so as to hold said jaw means in said final tightened position.

4. A gripping head arrangement for. use in a testing machine or the like comprising a pair of pressure cylinders mounted in aligned relationship upon a gripping head, the end of each cylinder remote from the other cylinder being connected to a source of pressure, a slidably movable member in each of said cylinders, each of said members having a threaded exterior portion, a jaw carried by each of said members, each member being so movable that its respective jaw can be moved into specimen gripping relationship with the jaw of the other member, and a position locking means threadedly mounted on the threaded exterior portionof each member, said jaws being movable by pressure in said cylinders so as to tightly grip a specimen to be tested, said position locking means being operable to locate positively said members with respect to said' cylinders and to hold said specimen in said tightly gripped position.

5. A gripping head arrangement for use in a testing machine or the like comprising a pair of pressure cylinders mounted in aligned relationship upon a gripping head, the end of each cylinder remote from the other cylinder being connected to' a source of pressure, a slidably movable member in each. of said cylinders, each of said members having a threaded exterior portion, a jaw carried by each of said members, each member being so movable that its respective: jaw can be moved into specimen gripping relationship with. the jawof the other member, and a position lockingmeans threadedly mounted on the threaded exterior portionof each member, said means being arranged to move said jaws toward each other to eifect an initial grippingof'a specimen, said' jaws being movable by pressurein said cylindersso' as to hold the specimen in a final tightened positiongsaid position locking means being operable to locate positively said members with respect tossaid cylinders and to hold said specimen in said final tightened position.

References Cited in the file of this patent UNITED STATES PATENTS 2,345,401 Lindegren Mar; 28, 1944 2,587,893 Pridy et al Mar. 4, 1952 2,656,748 Hugo et al Oct. 27, 1953' 2,660,440 Kurtz Nov. 24, 1953 2,681,581 Pearson June 22, 1954