US2697938A

US2697938A - Hydraulic compression tester for concrete

Info

Publication number: US2697938A
Application number: US398585A
Authority: US
Inventors: Tanaka Taketsugu
Original assignee: Individual
Current assignee: Individual
Priority date: 1953-01-08
Filing date: 1953-12-16
Publication date: 1954-12-28
Anticipated expiration: 1971-12-28

Description

1954' TAKETSUGU TANAKA HYDRAULIC COMPRESSION-TESTER FOR CONCRETE Filed Dec. 16, 1953 2 Sheets-Sheet l 1954 TAKETSUGU TANAKA HYDRAULIC COMPRESSION-TESTER FOR CONCRETE Filed Dec. 16, 1953 2 Sheets-Sheet 2 United States; Patent HYDRAULIC COMPRESSION TESTER FOR CONCRETE Taketsu'gu Tanaka, Tokyo-To, Japan Application December 16, 1953, Serial No. 398,585 Claims priority, application Japan January 8, 1953 2 Claims. (Cl. 73-94) The present invention relates to an improved hydraulic compression-tester for concrete.

The principal object of this invention is to provide a hydraulic compression-tester for concrete which is very small, light, portable and capable of applying a smooth receiving a test concrete-cylinder therein, a cover capable -of closing said main cyllnder after msertion of said concrete-cylinder into said ram, a pressure liquid chamber formed between the bases of the ram and the main cylinder, a pressure liquid generating device capable of feeding a pressure liquid into said chamber, and a meter for measuring the pressure in said chamber.

The present invention will be more easily understood by reference to the following detailed description taken in connection with the accompanying drawings, wherein:

Fig. 1 is a perspective view of an example of this invention, sectioned vertically and removed of the cover plate of the main cylinder.

Fig. 2 is a front view of the tester illustrated in Fig. l, sectioned partly.

Fig. 3 is a perspective view of the cover supporter of the tester illustrated in Figs. 1 and 2.

Fig. 4 is a perspective view of the guide piece employed in the tester illustrated in Figs. 1 and 2.

Fig. 5 is a magnified front view of the pressure meter of the tester illustrated in Figs. 1 and 2, sectioned partly.

Fig. 6 is a front view of the most usual hydraulic compression-tester heretofore in use.

Referring to Figs. 1-4, in the main cylinder 1, at the permanent end plate or base a hollow cylindrical ram 2 is slidably fitted, between the bases of said cylinder and the ram being formed a pressure liquid chamber 1' and the hollow part of said ram being formed to receive a test concrete-cylinder 3. The guide piece 4 is formed so that it may be slidable along the inner surface of the ram 2, may support said concrete-cylinder 3 at the vicinity of the both ends thereof and may be employed to take away the broken scrap of said cylinder 3 out of the ram 2. A press plate 5 which covers the concretecylinder 3 after insertion thereof into the ram 2 is employed to apply a uniform compression-load on the end surfaces of said cylinder 3. The main cylinder 1 is provided with a cover plate 6 capable of being screwed in the opening of the cylinder 1. A pump 7 is enclosed in a pump box 8 being filled up with press liquid and said box is attached to the main cylinder 1 at the front lowerpart thereof so that the main cylinder may be supported by said box and a foot 12 at an inclined position, where the main cylinder may take a slope of about against the horizontal surface. The pressure liquid chamber 1' and the pump 7 are communicated by a tube 9 which is supported at both ends thereof by said box 8 and foot 12. In the box 8 is arranged a release valve 10 capable of being controlled by a knob 10'. In the internal surface of the main cylinder 1 are made several ring-shaped slots 11 for receiving the pressure liquid. A pipe 9' communicated to said slot is arranged at the vicinity of the opening of the main cylinder 1 to return the pressure liquid being circulated through the contact surface between the cylinder 1 and the ram 2 into the pump box 8. On

2,697,938 Patented Dec. 28, 1954 ice a side of the pump box 8, a handle lever 13 capable of operating the plunger of the pump 7 is attached to the plunger lever 13 of the pump. A supporter 14 is attached on the pump box 8 to receive the cover plate 6 when it is taken off.

The pressure liquid chamber 1' is communicated to a pressure meter 15 arranged slopewise on the main cylinder 1, said slope being suitably selected so that the graduation plate may face perpendicularly to ones eyes.

As clear from the Fig. 5, the pressure meter 15 comprises a Bourdon tube 16, a fan-shaped cog-wheel 17, a connecting rod 18 for connecting one end of said tube 16 to said cog-wheel 17, a small pinion 19 being meshed with said cog-wheel 17, a large cog-wheel 20 attached on the shaft of said pinion 19 so that they may be rotated as one body, a pointing needle 21, a pinion 22 being fixed on the shaft of said needle 21 and meshed with said cog-wheel 20, a graduation plate 23, inside and outside

circular graduations

24 and 25, each of them being respectively correspondent to the first rotation and the second rotation of the needle 21, and a case 26 of the meter.

The operation of the tester illustrated as above will be more particularly understood by the following description. When a concrete-cylinder 3 to be tested is inserted under the condition put on the guide piece 4 into the ram 2, the center of said cylinder 3 coincides automatically with the center of the ram 2.

Then successively, the press plate 5 is put on the head of the cylinder 3, the cover plate 6 is screwed in the opening of the main cylinder 1 and pressure liquid is fed into the chamber 1' by operating the pump 7 by the handle 13.

With the increase of the pressure in said chamber 1' the ram 2 is pushed towards the cover plate 6 resulting in compressing the concrete-cylinder 3. At the same time with said compression, pressure liquid flows into the Bourdon tube 16 and set the end thereof in motion. This motion is transmitted to the fan-shaped cogwheel 17 through the connecting rod 18 and then to the needle 21 through the pinion 19, cog-wheel 20 and the pinion 22, whereby the magnified revolution of the needle 21 will be done. It is preferable that the gear-ratios between pmion 19 and the cog-wheel 17 and between the cog-wheel 20 and the pinion 22 are selected so that the motion of the end of the tube 16 may correspond to a suitable revolution of the needle 21 over one revolution, for instance, two revolutions.

In the manner as above, the load exerted to the concrete-cylinder 3 can be magnificently measured by the pressure meter 15.

During testing operation, if any breaking of the concrete-cylinder 3 commences, the revolution of the needle 21 stops and rather revolves backwards, so that the momentary indication of the needle 21 indicates the load capable of destructing the concrete-cylinder 3.

According to this invention, however, as will be clearly understood from said description taken in connection wlth the illustration in Figs. 1-5, the deformation of the cross-sectional surface of the main cylinder due to compression of the concrete-cylinder to be tested becomes exact circular form. Furthermore, when the thickness of the main cylinder is designed so that the expansion of the cross-sectional area of the main cylinder may be balanced by the contraction of said area, said expansion be- 1ng due to the liquid pressure exerted to the internal surface of said cylinder and said contraction being due to uniform tensile stress exerted to the wall of said cylinder, the leakage of the pressure liquid will be maintalned within a certain minimum amount without relation to the pressure magnitude of the pressure liquid or to the load exerted to the test concrete-cylinder.

Therefore, it is possible to apply a uniform and smooth load, that is, a true statical load to the test piece, whereby the exact indication of the graduation becomes always possible, because the pointing needle does not oscillate. Furthermore, friction does not occur between the main cylinder and the ram, so that an additional exactness would be obtained on the measurement.

As a whole, according to this invention, a portable and testersheretofore in usewillbe readily obtained.

In the embodiment of this invention, when a pressure meter of multi-revolving needle type is employed, as illustrated in Fig-5, as thepressure-meter,'magnifiedmeas- 'ur'ement will be obtained, which results in exact'tneasu'rement of delicatevariation of the load.

Heretofore, a Bourdon tube attached' to a compressiontester has been designed so that the pointing needle thereof may be revolved within 270 degrees, because it has been thought that even if the pointing-needleis re- -volved over 270 degrees,'the exactances of the measurement would not'be increased owing to the hysteresis phenomenon of the Bourdo'ntube, so that in the compression testersheretofore in use' it has been impossible to measure exactly the delicate variation of the load.

Howeven'when the load'varies only towards the increasing direction-as in thecaseof testing the strength of concrete, it is unnecessary to take the hysteresis phenomenon 1n conslderation-an'd it is allowable to graduate along the load increasing'branch of the hysteresis curve. Therefore, when the'motion of the-Bourdon' tube is magnlfied as in the case of this invention, the exactness would not be disturbed.

Since it is-obvious -that manychanges and modificatrons can be made in the above-described details without departing from the nature andspirit of the invention it is not limited within said illustraton.

' main cylinder provided with an end plate in one end thereof, a hollow cylindrical ram slidably disposed in said main cylinder the outer end of said ram being open for receiving "a test "concrete-cylinder therein, a cover for closing said main cylinder after insertion of said concrete-cylinder into said ram, the spacing of said ram and the end plate of said cylinder providing a pressure liquid chamber, a pressure liquidcgenerating device connected for feeding a pressure'liqui'd'into said chamber, and a pressure meter connecte'd forfmeasuring .the pressure in said chamber.

2. Compression-tester for concrete which comprises a main cylinder-provided with uansendzplatelin one end thereof, a hollow cylindrical ram slidably disposed in said'main cylinder, the-outer end'fsaid ram'being' open fortreceiving a test concrete-cylinder therein, a cover for closing saidmain' cylinderafter' insertion of said concretecylinder into said-ratmrsaid ram and' the end plate of said cylinder providing a pressure liquid chamber, a pressure liquid generating device connected for feeding a pressure liquid into said izcharn'ber, a tguide rpiece'trbeing slidable along the inner surface of said. ramiunder.thetconditions supporting said concrete-cylinder, rand a :pressure meter connected f for measuring L the :pressure 'in said chamber.

References Cited iniheafileofi this patent UNITED STATES "PATENTS Number Name Date 1,620,482 .McClelland Mar.:8, l927 1,985,598 Carver .'Dec. 25, 1934 2,030,640 Kinzl Febnll, 1936 2,414,550 Patch Ian. 2l, 194