US3483797A - Jacks and applications thereof - Google Patents

Jacks and applications thereof Download PDF

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Publication number
US3483797A
US3483797A US729963A US3483797DA US3483797A US 3483797 A US3483797 A US 3483797A US 729963 A US729963 A US 729963A US 3483797D A US3483797D A US 3483797DA US 3483797 A US3483797 A US 3483797A
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US
United States
Prior art keywords
piston
cylinder
jack
pressure
chamber
Prior art date
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Expired - Lifetime
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US729963A
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English (en)
Inventor
Lucien Diolot
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Societe Nouvelle Spidem
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Societe Nouvelle Spidem
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Publication date
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B66—HOISTING; LIFTING; HAULING
    • B66F—HOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD
    • B66F3/00—Devices, e.g. jacks, adapted for uninterrupted lifting of loads
    • B66F3/24—Devices, e.g. jacks, adapted for uninterrupted lifting of loads fluid-pressure operated
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B31/00—Rolling stand structures; Mounting, adjusting, or interchanging rolls, roll mountings, or stand frames
    • B21B31/16—Adjusting or positioning rolls
    • B21B31/20—Adjusting or positioning rolls by moving rolls perpendicularly to roll axis
    • B21B31/32—Adjusting or positioning rolls by moving rolls perpendicularly to roll axis by liquid pressure, e.g. hydromechanical adjusting
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
    • F15B15/08—Characterised by the construction of the motor unit
    • F15B15/14—Characterised by the construction of the motor unit of the straight-cylinder type
    • F15B15/1409—Characterised by the construction of the motor unit of the straight-cylinder type with two or more independently movable working pistons

Definitions

  • Known jacks are of two types, i.e. single acting and double acting. In the former kind driving pressure is exerted on only one of the faces of the piston, whereas in the latter type pressure is exerted on oppositely disposed faces of the piston.
  • the end of the working chamber is integral with the cylinder of the jack and thus is subjected to the effects of the pressure to the same extent as the walls of the cylinder.
  • the present invention relates to a jack which, as contrasted with existing jacks, affords a number of advantages stemming from the fact that the end of the working chamber is no longer fast with the corresponding end of the jack cylinder, but can slide within the latter, under the action of a judiciously applied auxiliary pressure.
  • a cylinder there are arranged within a cylinder at least a pair of pistons that are axially movable relative to each other.
  • One piston is provided with an enlarged area which functions as a wall for a chamber and a closure plate for the cylinder forms another wall for the chamber which is filled with a fluid of a predetermined value during operation.
  • Complementally formed portions of the cylinder and piston limit movement of the piston relative to the cylinder.
  • the aforesaid piston provided with the enlarged area is denoted hereinafter as the working piston and as pointed out, the enlarged surface area is arranged to move relative to the base portion and these surfaces thus form therebetween a precompression chamber.
  • the pressure in the precompression chamber is of a distinctly greater value than that which is introduced to the oppositely disposed surfaces of the several pistons with certain pressure responsive signal means being subjected to the pressure between the pistons and associated with a valve control means that is in operative relation with the precompression chamber.
  • the said precompression chamber can be instantaneously connected to the atmosphere by means of an ultra-rapid valve with a large opening, such as, for example, that described in US. Patent No. 3,277,794, mentioned hereinbefore, when, as is the case with the latter valve, all the control mechanism is directly fixed on the wall of the cylinder, the effectiveness of the valve is further increased owing to the over-pressure in the piping which may be present, causing pressure losses and thus slowing the discharge of the fluid.
  • the said piping constitutes, on the other hand, more particularly owing to the connections which they comprise, as many risks of leakages in the system.
  • the discharge of the precompression chamber is effected markedly more quickly since as soon as the valve referred to above opens, the second piston is driven towards the end of the precompression chamber by the action of the over-pressure prevailing in the working chamber, which adds its action to that of the initial pressure of the auxiliary fluid for discharging the said chamber.
  • One distinct advantage of the jack according to the invention is that it will permit the working piston to benefit from a considerable safety travel without disturbing the rigidity of the assembly, thus freeing itself of the effects of the compressibility of the working fluid.
  • Another advantage of the jack according to the invention is that, with the pressure of the fluid in the precompression chamber optionally available, it is possible instantaneously to connect the chamber with the atmosphere even in the absence of any action of the safety system previously described; for this, in fact, all that has to be done is to deliberately initiate the opening of the safety valve, either manually or automatically, under the action of any appropriate device, completely independent of that provided on the working fluid supply circuit.
  • Still another advantage of the jack according to the invention is that once the precompression chamber is emptied, it is possible to continue using the jack for a limited amount of time, for example, until the complete apparatus is returned to normal, taking precaution, of course, that overloads do not occur during such operation.
  • Yet another advantage of the jack according to the invention is that after some incident has caused the emptying of the precompression chamber there is no need, as in the case of conventional systems, to again drain the system conduits before placing it back into service, thus obviating losses of time which are often considerable.
  • FIG. 1 shows in vertical cross-section a single-acting jack according to the invention
  • FIG. 2 shows generally in vertical cross-section a clamping cylinder for a rolling mill, constituting one application of the jack according to the invention.
  • FIG. 1 shows a simplified adaptation of the invention with a single acting jack and a projecting piston; however, it is to be understood that the invention taught herein applies equally as well to double-acting rod-type jacks.
  • the jack cylinder 4 wherein three bores are formed, each of which increases in size towards one end of the cylinder, forms successively housings for the working piston 6, the precompression piston 5 and the closure plate 8 of the cylinder.
  • the conduit 12 is adapted to introduce a fluid into the working chamber formed between the oppositely disposed faces of the first and second pistons 5 and 6, respectively.
  • the pressure sensitive responsive means or detecting device which is connected to the conduit 12 that extends into the bore provided in the wall of cylinder 4.
  • the first piston 5 is provided with a shoulder which is arranged to abut against a corresponding complementally formed portion of the bore provided in the cylinder 4.
  • Auxiliary fluid is admitted through an inlet orinfice 26 into the precompression chamber 14 by means of the conduit which extends to the supply 24.
  • the ultra-rapid full-opening valve 16 intended to connect the chamber to the atmosphere is denoted in FIG. 1 merely by an arrow but a further detailed description of the actual operating mechanism will be later described in connection with FIG. 2.
  • the jack operates as follows:
  • auxiliary fluid is emitted into chamber 14 and the fluid is then maintain during the entire operation at a value very markedly higher than that of the working pressure which, by way of conduit 12, is admitted into the chamber 10 between the opposed pistons 5 and 6, respectively. From this instant, the jack is operated as a conventional jack, irrespective of type.
  • the pressure responsive signal means 19 acts instantaneously to cause the opening of the valve 16 and consequently to bring about an immediate decompression of the system so as to eliminate any danger or damaging fracture.
  • FIG. 2 discloses a clamping cylinder for a rolling mill and constitutes another application of the improved jack according to the invention.
  • the piston 6 comprises a rear portion of reduced diameter which is permitted to slide into or telescope the corresponding bore formed coaxially in the piston 5. This is a device whereby suitable guiding can be ensured for the piston 6 where a low height of the cylinder 4 is utilized.
  • clamping cylinder rests on the lower portion 1 of the upright of a rolling mill housing.
  • the chock depicted at 2 is provided with a lining 3 which is adapted to bear against the piston 6 of the clamping cylinder.
  • clamping cylinder of FIG. 2 comprises the same parts as that shown in FIG. 1.
  • a specially treated metal plate which is formed of a highly compacted or denser material which is availed of where the base portion 8 is constructed of cast iron or other cheap material and may be assembled in the chamber in any suitable manner.
  • sealing rings such as 9, 9a, 9b, 9c, 9d, 9e, are arranged on the peripheries of the two bores of the cylinder 4 as shown and at 9f there is provided a sealing ring which is situated adjacent the edge of the plate 7 and the complemental shoulder 9g which is provided on the cylinder 4. Also, as shown in FIG. 2, fluid is arranged to travel through the channel 10, then into the axial grooves 13 to ensure permanent communication between channel 10 and the transversely extending fluidized area 11.
  • fluidized channel 10 is of annular form.
  • the cylinder 4- is bored at 15 and provided at its outer terminal wall with a safety valve 16.
  • the reference numeral 18 denotes only one of the plurality of vents which are formed in the wall of the cylinder 4 to permit discharge of any air which may become entrapped within the cylinder when the piston S is raised to the position shown in FIG. 2.
  • Numeral 20 is, for example, the electromagnetic valve forming part of the system described in the aforesaid patent and permitting the instantaneous opening of the valve 16 in the event such is required.
  • a hydromechanical clamping device typical of those used in rolling mills which act on the volume of the fluid imprisoned with such a device and permit, more particularly, regulating the spacing desired between the rolls of the rolling mill with all necessary precision.
  • a pump 23 is adapted to supply the precompression chamber 14 by drawing fluid from a reservoir or sump 24 and passing it through line 22 to said chamber. It will be apparent that other means, such as a pressure fluid distribution network, can be made available for use in lieu of the system described.
  • this second embodiment is, generally speaking, identical to that described for the jack shown in FIG. 1.
  • the critical pressure in this case is the pressure admissible and envisaged during the course of the rolling operation. Also, it will be apparent that it is permissible to carry out all desired adjustments in a manner completely independent of the operation of the safety system by means of the two clamping cylinders provided on the rolling mill, whether it is at the beginning or during a rolling operation.
  • the increased travel of the jack according to the present invention constitutes a particularly advantageous arrangement for use in rolling mills.
  • a fluid operated jack comprising a cylinder provided with a base portion forming one Wall of a chamber, a first piston means, said piston means including a portion forming another wall of the chamber, said piston further arranged to be normally supported above the base portion of the cylinder by a pressure medium of predetermined value introduced into said chamber, a second piston in said cylinder means arranged to introduce a pressure of lesser value than said first-named pressure between the first and second piston means to actuate the latter and pressure responsive signal means, said pressure responsive signal means adapted to detect excessive force on said second piston and reduce the pressure in said chamber.
  • seal means are spacedly arranged between the cylinder and said first and second piston means.
  • seal means are spacedly arranged between the cylinder and said first and second piston means.
  • a fluid operated jack according to claim 1, wherein a discharge conduit connects the end section of the working chamber at the side opposite from that occupied by the working piston with the atmosphere.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Fluid Mechanics (AREA)
  • Geology (AREA)
  • Structural Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Crushing And Grinding (AREA)
  • Actuator (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Jigs For Machine Tools (AREA)
  • Earth Drilling (AREA)
US729963A 1967-05-22 1968-05-17 Jacks and applications thereof Expired - Lifetime US3483797A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR107300A FR1539009A (fr) 1967-05-22 1967-05-22 Perfectionnement aux vérins et applications

Publications (1)

Publication Number Publication Date
US3483797A true US3483797A (en) 1969-12-16

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Family Applications (1)

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US729963A Expired - Lifetime US3483797A (en) 1967-05-22 1968-05-17 Jacks and applications thereof

Country Status (5)

Country Link
US (1) US3483797A (fr)
DE (1) DE1756451A1 (fr)
ES (1) ES353940A1 (fr)
FR (1) FR1539009A (fr)
GB (1) GB1221660A (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2459692A1 (fr) * 1979-06-26 1981-01-16 Secim Dispositif d'entrainement de bande

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3265345A (en) * 1964-05-14 1966-08-09 Michel A E Vuichard Seat suspension for a tractor and the like
US3267677A (en) * 1963-05-09 1966-08-23 Leo C Bollar Impact forming machine

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3267677A (en) * 1963-05-09 1966-08-23 Leo C Bollar Impact forming machine
US3265345A (en) * 1964-05-14 1966-08-09 Michel A E Vuichard Seat suspension for a tractor and the like

Also Published As

Publication number Publication date
FR1539009A (fr) 1968-09-13
ES353940A1 (es) 1969-10-16
GB1221660A (en) 1971-02-03
DE1756451A1 (de) 1970-04-02

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