Power plants – Pressure fluid source and motor – Pulsator
Patent
1981-10-30
1985-02-19
Hershkovitz, Abraham
Power plants
Pressure fluid source and motor
Pulsator
60583, 60589, 60591, 60593, 60594, F15B 700
Patent
active
044997280
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a national phase application corresponding to PCT No. FR 81/00034 filed Mar. 11, 1981 under the Patent Cooperation Treaty and in turn based upon French Application No. 80 05 955 filed Mar. 12, 1980 under the International Convention (the priority of which is claimed).
FIELD OF THE INVENTION
This invention relates to a hydraulic press mechanism and, more particularly, to a mechanism providing, in succession, a fast approach stroke and then a work stroke with a substantial developed stress, in operations such as riveting, marking, clamping and, more generally, in any operations in which the work stroke can be relatively short by comparison with the approach motion.
BACKGROUND OF THE INVENTION
Presently known hydraulic press mechanisms often consist of a single movable piston. In order to have an approach stroke, it is necessary, in that case, to displace all more hydraulic fluid as this stroke is greater. This can essentially be accomplished only by a pump, i.e., by a device which is complex with respect to the simplicity of the jack itself. Displacement of the fluid with a manual pump has to be effected using a large number of manoeuvers which of course make the operation slow and impractical.
Certain known devices provide a substantial and rapid approach displacement but require for this purpose a second jack and corresponding distribution chambers in order to transport the fluid.
Certain existing presses provide a fast approach stroke by means of the high flow rate of a low pressure pump, and a slow work stroke by means of the low flow rate of a high pressure pump. The feeding and control device, in the latter case, is costly with regard to the desired result.
Finally, certain devices are known which provide the same results at the price of greater complexity, for, in particular, control can only be effected using compressed air which must be introduced in several places of the device.
OBJECTS OF THE INVENTION
The object of this invention is to overcome all of these disadvantages by providing a press mechanism whereby, by application of a moderate stress at a single point of the device, a fast approach stroke is first induced until the tool comes into contact with the part to be pressed, and then from this point on, a work stroke is provided during which the device multiplies by itself the stress exerted, so that the part is subjected to the large stress desired. The invention also aims to achieving other results, in particular, use of an entirely hydraulic operation, by providing an automatic compensation of volume variations in the fluid related, for example, to operational leaks of the seals, these leaks becoming substantial when the device has gone through several hundred thousand operations and when a very fluid oil is used in order to obtain a high operational speed.
SUMMARY OF THE INVENTION
To this effect, the invention provides a hydraulic mechanism comprising a stem, on which the control action of the device is exerted, and a main body, which can be moved along one and the same axis in a fixed guiding bore, means being provided for the non permanent releasable locking of the body with respect to the stem, said body comprising a chamber filled with an incompressible fluid, in which a primary piston penetrates extending said stem, this chamber communicating, on the one hand, with an expansible casing axially immobilized around the body and which can be pressed against the wall of the previously mentioned bore so as to block the body with respect to the bore and, on ther other hand, with a cylindrical chamber in which is slidingly mounted a secondary piston, the latter being integral with a work tool and subjected to the action of a return spring.
The mechanism thus defined can cause the tool to describe an approach stroke followed by a work stroke, while being controlled only by a member which will be known in this disclosure as a stem, the work stroke being started at the time at which the tool comes into contact with the par
REFERENCES:
patent: 1659157 (1928-02-01), Prouty
patent: 3059433 (1962-10-01), Hirsch
patent: 3266415 (1966-08-01), Palmer
patent: 3830061 (1974-08-01), Severinsson
patent: 4249380 (1981-02-01), Melendy
patent: 4271671 (1981-06-01), Smeets
patent: 4288987 (1981-09-01), Grullmeier
patent: 4300351 (1981-11-01), Grullmeier
Hershkovitz Abraham
Ross Karl F.
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