Fluid cylinder assembly

Details Fluid cylinder assembly Fluid cylinder assembly

1999-08-17

2001-04-17

Ryznic, John E. (Department: 3745)

Expansible chamber devices

With inspection window in expansible chamber wall portion

With lock

C092S161000

Reexamination Certificate

active

06216581

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a fluid cylinder assembly incorporating load transducers (as defined hereinafter) for detecting the thrust exerted by a piston rod.
2. Description of the Prior Art
The prior art fluid cylinder assembly is useful for various purposes such as subjecting a component part of a machine to press fit, clamping, chucking, roller pressure or stamping. According to the purpose for which the fluid cylinder assembly is used, it is necessary to detect the magnitude of thrust exerted by a piston rod or the magnitude of load acting on the component part.
For example, when a component part of a machine is subjected to press fit, force exerted thereon is measured with a view to using the measured value for passing a judgment on whether or not the component part has been properly subjected to press fit.
It is known to measure such force by means of a load cell carried either on the outer end of the piston rod (as disclosed in Japanese Utility Model Registration No. 2,569,871) or on a cap cover secured on the end of a cylinder tube opposite the end at which the piston rod is extendible and retractable.
The load cell carried on the outer end of the piston rod assures that the results of measurement are obtained with a high degree of accuracy, because the magnitude of load acting on the component part can be directly measured. The trouble is that a lead wire extending outwardly of the load cell moves as the piston rod moves. Therefore, a supporting member or members have to be employed as a means to movably support the lead wire and prevent it from being disconnected.
In case of the load cell carried on the cap cover, the output taken from the load cell contains not only the magnitude of load acting on the component part but also the magnitude of gravity acting on the fluid cylinder assembly per se. Especially when the fluid cylinder assembly is mounted on a vertical supporting structure in cantilever fashion, i.e., with the cap cover allowed to support the gross weight of the fluid cylinder assembly, the output taken from the load cell contains not only the magnitude of thrust acting on the component part but also the magnitude of angular moment acting on the fluid cylinder assembly per se. A marked decline in the accuracy of measurement results therefrom.
SUMMARY OF THE INVENTION
The present invention is concerned with eliminating the aforesaid difficulty. As such, the primary object of the invention is to provide a fluid cylinder assembly which precludes the movement of a lead wire extending outwardly of a load cell and allows the results of measurement to be obtained with a high degree of accuracy.
As indicated above, the invention is concerned with a fluid cylinder assembly of the kind provided with a cylinder tube
11
in which a piston
12
coupled by a piston rod
13
operates. The cylinder tube
11
has one end connected with a rod cover
14
. The piston rod
13
passes through an aperture in the rod cover
14
and projects outwardly. In one described embodiment, the rod cover
14
is associated with means
27
for mounting the fluid cylinder assembly on a frame FM and a transducer which converts a magnitude in load axially acting thereon to a magnitude in voltage or current and develops an electric signal (hereinafter referred to as the “load transducer”).
In another described embodiment, the load transducer includes two flanges lying on, and perpendicular to, the axis of the fluid cylinder assembly and disposed in spaced parallel relation with each other. A thin cylindrical wall capable of elastic deformation is interposed between, and integrally formed with, these two flanges and extends coaxially of the fluid cylinder assembly. At least one strain sensor is mounted on the thin cylindrical wall.


REFERENCES:
patent: 3664184 (1972-05-01), Dyer
patent: 4058178 (1977-11-01), Shinohara et al.
patent: 4860639 (1989-08-01), Sakaguchi
patent: 5163660 (1992-11-01), Yamaoka et al.
patent: 5905212 (1999-05-01), Moses et al.
patent: 2569871 (1998-02-01), None

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