AU709735B2

AU709735B2 - Hydraulic ram apparatus

Info

Publication number: AU709735B2
Application number: AU16544/97A
Authority: AU
Inventors: Malcolm Stuart Story
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-03-29
Filing date: 1997-03-25
Publication date: 1999-09-02
Anticipated expiration: 2017-03-25
Also published as: AU1654497A

Description

2 connected to the reservoir through a valve which is opened. Such springs are prone to weaken or fail, requiring additional maintenance costs and, further, are not a particularly effective means for retraction.

The applicant believes that the present invention alleviates one or more of the above disadvantages and provides a hydraulic ram apparatus which will be reliable and efficient in use. In particular, the present invention aims to provide hydraulic ram apparatus in which the ram may be more rapidly advanced than achieved by using hydraulic pressure along.

The present invention in one aspect thus resides broadly in a hydraulic ram 9* apparatus, said apparatus including: o* a ram means having a cylinder and a piston adapted for motion within said cylinder; a hydraulic supply means for supplying hydraulic fluid to said ram means; and pneumatic supply means for supplying pressurized pneumatic fluid to said hydraulic supply means.

The hydraulic supply means and the pneumatic supply means are preferably arranged such that the pneumatic fluid 3 does not enter into the ram means upon supply of the pneumatic fluid to the hydraulic supply means.

Preferably, the hydraulic supply means includes an hydraulic reservoir, and the pneumatic supply means is adapted to apply pneumatic pressure and/or supply pressurized pneumatic fluid to the hydraulic reservoir.

Pneumatic return means may be provided for returning the piston from an extended position to a retracted position.

Accordingly, the pneumatic supply means may be connected to the cylinder in a manner to cause movement of the piston to a retracted position.

S"The hydraulic supply means preferably includes pumping means such as a manually operated or powered hydraulic pump. The hydraulic pump may be operated to pump hydraulic fluid from the hydraulic reservoir to the cylinder to advance the piston.

The hydraulic pump preferably includes check valve means such that the hydraulic fluid may pass through the pump in one direction only, suitably, in the direction of advancing the piston toward and/or to its extended position.

Thus, upon application of pneumatic pressure to the reservoir, hydraulic fluid under the influence of pneumatic pressure is caused to flow from the hydraulic fluid reservoir to the cylinder, whereupon the piston is advanced until a desired position is reached at which supply of pneumatic pressure to the reservoir may be terminated. Further advance of the piston, or increasing the force applied in the direction of extending the piston, may be achieved by pumping the hydraulic fluid by operation of the hydraulic pump.

For return of the piston from its advanced position to its retracted position, the connection between the cylinder and reservoir is opened and the opposing pneumatic pressure may return the piston to its retracted position.

In a further aspect, this present invention resides broadly in a method of operating hydraulic ram apparatus, said method including the steps of: providing hydraulic ram apparatus having a piston and cylinder, said hydraulic ram apparatus including a hydraulic reservoir in fluid connection with the cylinder; a applying a pneumatic pressure to said reservoir to cause hydraulic fluid to flow from said hydraulic reservoir to said cylinder to cause advancement of said piston; maintaining said pneumatic pressure until a desired position of said piston is reached; and operating hydraulic pumping means to further advance said piston or to increase the force applied in the direction of extending said piston.

The pneumatic pressure may be maintained or released upon the operation of the hydraulic pumping means.

The method may further include the operation of valving to release the pneumatic pressure from the hydraulic reservoir to permit the piston to retract in the cylinder.

The method of the invention may further include the step of applying the pneumatic 0 pressure to the cylinder to urge the piston to its retracted position. The pneumatic pressure for retracting the piston may be constantly applied to the cylinder to act as a bias to the piston against which the hydraulic fluid may act to cause advancement of the piston or may be applied only to retract the piston.

Whilst the invention has been described by reference to the rapid advancing of a piston in a cylinder through application of pneumatic pressure, it may equally be R~ 0/r ~Yr~ 6 applied to the rapid retraction of a piston in a cylinder.

In order that this invention may be more readily understood and put into practical effect, reference will now be made to the accompanying drawings which illustrate a typical embodiment of the invention and wherein:- Fig. 1 is a schematic diagram of a hydraulic circuit for a conventional hydraulic press of the prior art; o oo °0 ~and 1. 0 Fig. 2 is a schematic diagram of a hydraulic circuit for a hydraulic press of the present invention.

Referring to Fig. 1, there is illustrated a hydraulic circuit for a conventional hydraulic press 10 including a .cylinder 11 having a piston assembly 12 arranged therein 15 for reciprocation between an extended position in the :direction of arrow 13 and a retracted position in the direction of the arrow 14.

The piston assembly 12 is advanced by operation of a pump through which hydraulic oil 15 is pumped from a reservoir 25 through an oil suction line 26 and an oil delivery line 27 to the cylinder 11. The hydraulic oil cannot return from the cylinder 11 to the pump because of the provision of respective non-return valves 22 in the pump 20. The hydraulic oil 15 is pumped by operation of a plunger 21 in the pump In order to permit the retraction of the piston assembly 12 into the cylinder 11, a valve 16 is provided in a return line 28 through which, upon opening of the valve 16, hydraulic fluid 15 may pass from the cylinder 11 through to the reservoir 25. In order to allow for pumping of the hydraulic fluid 15 from the reservoir and the return of hydraulic oil 15 to the reservoir 25, a 10 vent 24 is provided in the reservoir eo Referring now to Fig. 2, there is illustrated hydraulic oooeQ apparatus according to the present invention including an hydraulic ram 30 which includes a cylinder 31 having a piston assembly 32 mounted therein for reciprocation between an extended position in the direction of the arrow 33 and a retracted position in the direction of the arrow 34. The cylinder 31 is in fluid connection with a :pump 20 of the same type as that shown in Fig. 1 via an oil delivery line 37.

An oil reservoir 35 is in fluid connection with the suction side of the pump 20 through an oil suction line 36. Additionally, an oil return line 38 having a valve 16 therein is provided in a similar fashion to that described in relation to Fig. 1.

8 The reservoir 35 is not vented as in the case of the reservoir 25 shown in Fig. 1, but rather the reservoir is connectable to a compressed air supply via a reservoir air line The compressed air supply 40 includes a control valve 41 through which compressed air may pass from an air pressure line 44 connected, for example, to a conventional compressor charged air supply system. The control valve 41 includes a valve member 48 which, in the 10 position as shown, permits air pressure from the air e e o pressure line 44 to be transmitted through a reservoir port 55 and through the reservoir air line 45 to the reservoir Thus, in the position as shown, air pressure is applied to the oil 15 in the reservoir 35 urging the oil 15 to flow through the oil suction line 36, the pump 20 via the non-return valves 22 and the oil delivery line 37 to the cylinder 31 which in turn urges the piston assembly 32 to advance in the direction of the arrow 33.

Moving the valve member 48 in the direction of the arrow 49 to the position shown in dotted outline permits air pressure from the air pressure line 44 to be transmitted through a cylinder port 56, a cylinder air line 46 in fluid connection between the control valve 41 and the cylinder 31 to pressurize the piston rod end of the 9 cylinder 31. Upon opening of the valve 16, the oil 15 in -1 the cylinder 31 at the piston end of the cylinder 31 is permitted to return to the oil reservoir 35 through an oil return line 38 allowing the piston assembly 32 to retract in the direction of the arrow 34 under the influence of the air pressure supplied through the line 46.

During the advancement of the piston assembly 32 in the direction of the arrow 33, air is vented from the of*: 10 cylinder 31 through the cylinder port 56 and a cylinder exhaust 43 provided in the control valve 41. During the 0.:006 retraction of the piston assembly 32 in the direction of the arrow 34, the oil reservoir 35 is vented through the ooo• reservoir air line 45, reservoir port 55 and a reservoir exhaust 47.

If desired, the control valve 41 and the valve 16 may be interlocked such that the valve 16 is in the closed S"position when the control valve 41 is in the position shown in solid outline, whereas the valve 16 is in the open position when the control valve 41 is in the position shown in dotted outline.

Additionally, upon or after the advancement of the piston assembly 32 towards its load, the pump 20 may be operated through reciprocation of its plunger 21 in order to apply hydraulic pressure to the cylinder 31 through the nonreturn valve 22 and the oil delivery line 37.

In use, a source of compressed air is connected through line 44 to the common port of the control valve 41 which comprises in this embodiment a five-port two-way directional control valve. The valve member 48 is spring loaded by the spring 42 to normally maintain air pressure on the piston assembly 32 to provide a bias against .:69 movement of the piston assembly and provide for 10 retraction of the piston assembly 32 when the valve 16 is opened to allow oil 15 from the cylinder 31 to return to the reservoir 35. As oil 15 returns to the reservoir the displaced air is free to escape via the reservoir port exhaust 47.

15 When rapid advance of the piston assembly 32 is required, the control valve member 48 is advanced against the bias provided by the spring 42 to move to the position shown thereby exhausting air pressure from the lower side of the piston assembly 32. At the same time, air pressure is applied to the oil reservoir 35 through the line 45 to pressurize the reservoir 35 and cause oil to pass from the reservoir 35 through the valves 22 within the pump and into the top side of the piston assembly 32 causing the piston assembly 32 to advance to a desired position adjacent a load, for example an article to be pressed.

At this position the valve member 48 is released so that 11 the biasing spring 42 returns the valve member 48 to the position shown in dotted outline.

The piston assembly 32 will maintain this advanced position as the check valves 22 prevent oil returning to the reservoir 35. The hand operated pump 20 may then be operated to further advance the piston assembly 32 and apply a pressing force to an article to be pressed.

When the pressing operation is terminated, the valve 16 is opened to allow oil to flow from the cylinder 31 back 10 to the reservoir 35 under the influence of air pressure applied by the valve 41 to the cylinder 31 through the line 46 thus causing the piston assembly 32 to retract.

*o* e Suitably, the valve member 48 is provided with a push button 50 to facilitate its operation by hand for overcoming the bias of the spring 42, It will be appreciated that the components of the apparatus described may vary from that illustrated and described. For example, the valve 41 may be any form of valve such as a spool valve or a poppet valve or a combination thereof. In addition, the valve 16 may be conveniently incorporated into the body of the pump Whilst the pump 20 is normally a hand operable plunger pump, it may be a power operated pump if desired.

Further the hydraulic circuit described may be reversed in its connection to the ram 30 to cause rapid retraction of the piston assembly 32 under the influence of pneumatic pressure as described.

It will, of course, be appreciated that the piston assembly 32 may be coupled to any tool or implement required in a pressing or other operation.

Thus whilst the above has been given by way of illustrative example of the invention, all such modifications and variations thereto as would be apparent 10 to persons skilled in the art are deemed to fall within the broad scope and ambit of the invention as defined in the following claims.

o* C o• 13 THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS: 1. A hydraulic ram apparatus, said apparatus including: ram means having a cylinder and a piston adapted for motion within said cylinder; hydraulic supply means for supplying hydraulic fluid to said ram means; and Spneumatic supply means for supplying pressurized pneumatic fluid to said hydraulic supply means.

2. An apparatus as defined in claim 1 wherein said hydraulic supply means and said pneumatic supply means are arranged such that said pneumatic fluid does not enter said ram means upon supply of said pneumatic fluid to said hydraulic supply means.

3. An apparatus as defined in claim 1 or claim 2 wherein said hydraulic supply means includes a hydraulic reservoir, said pneumatic supply means being adapted to apply pneumatic pressure and/or supply pressurized pneumatic fluid to said hydraulic reservoir.

Claims

4. An apparatus as defined in claim 3 further including a pneumatic return means for returning said piston from an extended position to a retracted position. An apparatus as defined in claim 3 or 4 wherein said pneumatic supply means is connected to said cylinder in a manner to cause movement of said piston to a retracted position.
6. An apparatus as defined in any one of claims 3 to 5 wherein said hydraulic supply means includes pumping means, said pumping means including a manually operated or powered hydraulic pump.
7. An apparatus as defined in claim 6 wherein said hydraulic pump supplies hydraulic fluid from said hydraulic reservoir to said cylinder to advance said piston.
8. An apparatus as defined in claim 6 or claim 7 wherein said hydraulic pump includes check valve means allowing said hydraulic fluid to pass through said pump in one direction only.
9. An apparatus as defined in claim 8 wherein said one direction is advancing said piston toward and/or to its extended position. A method of operating a hydraulic ram apparatus, said method including the steps of: providing hydraulic ram apparatus having a piston and cylinder, said hydraulic ram apparatus including a hydraulic reservoir in fluid connection with the cylinder; applying a pneumatic pressure to the said reservoir to cause hydraulic fluid to flow from said hydraulic reservoir to said cylinder to cause advancement of said piston; maintaining said pneumatic pressure until a desired position of said piston ,•is reached; and operating hydraulic pumping means to further advance said piston, or oo •I increase the force applied in the direction of extending said piston.
11. A method as defined in claim 10 wherein said pneumatic pressure is maintained or released upon operation of said hydraulic pumping means.
12. A method as defined in claim 10 or claim 11 further including the operation of valving to release said 16 pneumatic pressure from said hydraulic reservoir to permit said piston to retract in said cylinder.
13. A method as defined in any one of claims 10 to 12 further including the step of applying said pneumatic pressure to said cylinder to urge said piston to its retracted position.
14. A method as defined in any one of claims 10 to 13 wherein said pneumatic pressure for retracting said piston is constantly applied to said cylinder to act as a bias to said piston against which said hydraulic fluid may act to cause advance and/or retraction of said piston. S
15. A new hydraulic ram apparatus substantially as described herein with SS reference to Fig 2 of the drawings. *YSS*S
16. A new method of operating a hydraulic ram apparatus 10 substantially as described herein with reference to Fig 2 of the drawings. DATED THIS DAY OF June 1999 MALCOLM STUART STORY PIZZEYS PATENT TRADE MARK ATTORNEYS 17 ABSTRACT A hydraulic ram 30 includes a cylinder 31 having a piston assembly 32 mounted therein for reciprocation between an extended 33 and retracted 34 position. The cylinder 31 is connected to a pump 20 via an oil delivery line 37. An oil reservoir 35 is connected to the suction side of the pump 20 through an oil suction line 36. An oil return line 38 having a valve 16 therein is also provided. The reservoir 35 is connected to a compressed 10 air supply via a reservoir air line 45. A compressed air supply 40 includes a control valve 41 through which g :compressed air passes from an air pressure line 44 connected to a conventional compressor charged air supply system. The control valve 41 includes a valve member 48 15 which, when in an operating position, permits air pressure from the air pressure line 44 to be transmitted through a reservoir port 55 and through the reservoir air 06o .line 45 to the reservoir 35. Air pressure is applied to the oil 15 in the reservoir 35 urging the oil 15 to flow 20 through the oil suction line 36, the pump 20 via the non- return valves 22 and the oil delivery line 37 to the cylinder 31 which in turn urges the piston assembly 32 to advance in the direction 33. Moving the valve member 48 in the direction 49 permits air pressure from the air pressure line 44 to be transmitted through a cylinder port 56, a cylinder air line 46 in fluid connection between the control valve 41 and the cylinder 31 to pressurize the piston rod end of the cylinder 31.