US3468222A - Control for a ramming hammer with hydraulic drive - Google Patents

Description

Sept. 23, 1969 CORDES ET AL 3,468,222

CONTROL FOR A RAMMING HAMMER WITH HYDRAULIC DRIVE Filed June 30, 1967 3 Sheets-Sheet 1 6%Wm M 19 Sept. 23, 1969 H. H. CORDES ET AL 3,453,222

CONTROL FOR A RAMMING HAMMER WITH HYDRAULIC DRIVE Filed June so. 1967 s Sheets-Sheet 2 &@W I was Sept. 23, 1969 H, CORDES ETAL 3,468,222

CONTROL FOR A RAMMING HAMMER WITH HYDRAULIC DRIVE Filed June 30, 1967 3 Sheets-Sheet :3

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3.5w a K 32 8 j 445' mum mfaq United States Patent 3,468,222 CONTROL FOR A RAMMING HAMMER WITH HYDRAULIC DRIVE Hugo H. Cordes, 7 Rulantweg, Hamburg 50, Germany, and Hans A. Kroger, Hamburg, Germany; said Kriiger assignor to said Cordes Filed June 30, 1967, Ser. No. 650,411 Claims priority, application G6ermany, July 6, 1966,

Int. Cl. F61121/04 US. Cl. 91222 8 Claims ABSTRACT OF THE DISCLOSURE Background of the invention The invention relates to a ram with hydraulic drive. Such rams are used on mobile carrier equipment for smashing or compacting purposes. They are also employed to drive in sheet piles, piles or the like while suspended from a rope or guided by a ram guide.

The object of the invention is to provide a ram of high efficiency with handy dimensions which is mobile and may be employed in any position i.e. not only with the working member moving in the vertical direction.

Another object is to provide a ram with a simple and reliable automatic hydraulic control which allows for a wide variety of sequence of strokes.

The ram comprises a ram block which is movable with respect to the ram housing and which is connected with the piston of a hydraulic cylinder to which pressure fluid is supplied at a substantially constant rate from a pressure fluid pump situated outside the ram.

Summary of the invention .block a greater impact velocity than would correspond to the quantity of liquid delivered by the pump. The accumulators arranged near to the control device reduce the pressure fluctuations in the supply and discharge lines and make available a suflicient quantity of pressure fluid for the control. Thereby, a safe and quick control is made possible. There is also a practically steady supply and drain flow taking place through the hoses, thus sparing them.

In an especially preferred embodiment of the invention the piston which is displaceably guided in a working cylinder is connected with the ram block by means of a hollow piston rod. The volume portion of the working cylinder through which the piston rod passes, may be steadily connected to the delivery side of the pump. A hollow control rod adapted to be pushed into the holice low piston rod passes through the upper volume portion of the working cylinder. The control rod connects at times the hollow space of the piston rod with the upper portion of the working cylinder by means of openings. Moreover, the hollow control rod connects permanently the hollow space of the piston rod with a control chamber. This control chamber is open to at least one accumulator cylinder.

The control supported in the ram housing for longitudinal movement therein. Moreover, the control rod is connected to a valve spool controlling the liquid flow in the ram. The control rod may also be stationarily supported in the ram housing. Then, the valve spool will be arranged separately and moved by a piston projecting into the control space. The pressure fluid displaced from the cavity of the piston rod during the upward movement of the ram block at first pushes back a storage piston arranged in a first storage cylinder, to a stop and then displaces the valve spool against the action of a small piston pressurized by the supply pressure, and/or against a spring.

It may be recommendable to provide the control space with a second storage cylinder in which a storage piston designed as a separating piston is arranged, the side of which faces away from the control space which is subjected to the supply pressure.

In this manner, at first, a very exact and reliable reversal is effected by means of the valve spool and thereafter the working piston is still capable of moving a further small distance in the same direction while displacing one storage piston.

The ram designed in accordance with the invention may be employed with any angle with respect to the vertical line.

Further improvements and suitable features of the invention are explained by way of the drawing which shows some embodiments in a diagrammatic view.

Brief description of the drawing FIG. 1 shows a ram for smashing or compacting operations, which is pivotally connected to the cantilever of a dredge or other building machinery vehicle, the pressure fluid feed with constant flow of delivery being shown diagrammatically.

FIG. 2 shows the same ram however with a ram plate having the ram block beating thereon, for driving in posts and sheet piles.

FIG. 3 shows a longitudinal sectional view of one embodiment of the control device for automatically controlling the liquid flow within the ram housing, the accumulators being shown diagrammatically on a reduced scale.

FIG. 4 shows a longitudinal sectional view taken on another embodiment of the control device.

Description of the preferred embodiments The two control devices according to the invention shown in the FIGS. 3 and 4 essentially differ from each other in that the embodiment of FIG. 3 makes use of an axially displaceable control rod and the embodiment of FIG. 4 uses a stationary one. Like reference numerals are used in the figures for corresponding parts.

In accordance with FIGS. 1 and 2 pressure fluid is supplied to thehousing 1 of the ram from apump 39 after themaster valve 40 has been opened. Said pressure fluid moves theram block 5 supported in theram housing 1 up and down. In this operation, the ram housing (FIG. 1) mounted at acantilever 37 of a mobile building machine may be guided over the ground in such a manner that theram block 5 strikes the ground by itstool 41. Theram housing 1 may also be suspended freely (FIG. 2) or with guidance in a ram guide and put onto apost 35 with anintermediate ram plate 34, the ram block beating onto the post via theram plate 34 and driving the same into the ground.

Thepump 39 with the main valve and accessory is arranged on the carrier stand, i.e. themobile building machine 36. Thepressure line 44 of thepump 39 is con nected with thesupply line 9 of an automatic hydraulic control device by means of ahose 42, said control device being arranged in theram housing 1. In a corresponding manner, ahose 43 is used to connect return line to the controldevice return line 16. Theram housing 1 contains a workingcylinder 2 with workingpiston 3,piston rod 4 and aram plate 5 fastened thereat. Thepiston rod 4 is provided with acavity 6 with ahollow plunger rod 7 adapted to be plunged thereinto. The inflowing pressure fluid in thesupply line 9 is controlled by avalve spool 8, the pressure fluid being capable, for example, of permanently biasing the underside of the workingpiston 3 via theline 10.. Theplunger 7 is provided withbores 11 communicating thecavity 6 of thepiston rod 4 with theupper volume portion 12 of the workingcylinder 2 with theram block 5 being near its lowest position.

A compressed-airhydraulic accumulator 13 is inserted in thesupply line 9 which may be designed as a bubble accumulator with agas bubble 14 and abottom valve 15 or also as a piston accumulator.

A compressed-airhydraulic accumulator 17 for low pressure is fitted in thereturn line 16. Thebore 18 of theplunger rod 7 is permanently in communication with thecontrol chamber 19 and astorage cylinder 20, thepiston 21 of which is subjected to supply pressure on its other side via theline 22. Adifferential piston 24 is fitted inanother storage cylinder 23 the large piston surface of which is in communication with theupper volume portion 12 of the workingcylinder 2 via theline 25. Thesmall surface 26 ofpiston 24 is permanently in communication with thecavity 6 via thehollow plunger rod 7. Thisdifferential piston 24 is additionally permanently biased by a psring or by apiston 27 subjected to supply pressure. Its stroke is limited by theadjustable abutment member 28. The small piston surface and its annular surface may be interchanged. Instead of the emerging action of the small piston as shown in the drawing, it is also possible to overrun slots.

FIG. 3 shows theplunger rod 7 rigidly connected with thevalve spool 8 while movably supported in theram housing 1. Theplunger rod 7 is pressed into a position in which thevalve spool 8 fixed thereto causes a lifting movement of theram block 5, by a spring or asmall piston 29 subjected to supply pressure. In this operation, the annular area of thedifferential piston 24 is in communication with thecavity 6 of thepiston rod 4 via thepassage 30 and thebore 18.

In the embodiment shown in FIG. 4, theplunger rod 7 which may be axially adjusted by means of an adjustingscrew 31, is rigidly connected with theram housing 1. The liquid displaced from thecavity 6 acts on thepiston 32 connected with the valve spool S and, with high pressure, causes the reversal against a permanently effective return force for example by thespring 33. This spring may also be replaced by asmall piston 29 subjected to supply pressure as shown in FIG. 3.

The mode of operation is as follows:

Thevalve spool 8 is initially in a position effective to cause the lifting movement of the ram block 5 (FIG. 3). Before lifting, thebores 11 are open so that a balance may take place between thevolumes 12 and 6. During the lifting movement, thesebores 11 become blocked by thepiston 3. The liquid displaced from thevolume 6 flows now through the upper bores of theplunger rod 7 and first displaces thedifferential piston 24 against the force of thesmall piston 27 to theabutment member 28. Upon further increase of the pressure withinvolume 6, until the upward force acting onplunger 7 exceeds the 4 downward force onpiston 29, theplunger 7 will be moved upwardly shiftingvalve 8 to its upper position. This occurs because thesmall piston 29 has a smaller diameter than theplunger rod 7.

In accordance with FIG. 4, the reversal is effected in that a liquid pressure smaller than the supply pressure and acting on thepiston 32, suffices to revert thevalve spool 8 against the force of thespring 33. Instead of thespring 33, asmall piston subjected to the supply pressure and having a diameter smaller than that of thepiston 32 may effect the return movement.

After reversal ofvalve 8, theram block 5 will continue its upward movement due to inertia. Thereby, pressure liquid is pressed into theaccumulator 13, and liquid is displaced from thecavity 6 into thestorage cylinder 20. This liquid moves thepiston 21 against the supply pressure and the displaced liquid is pressed into theaccumulator 13.

Theram 3 will stop its upward movement upon forcing fluid intoaccumulator 13, and as the supply fluid communicates withchamber 12 andexhaust passage 16 is blocked theram 3 is forced downward. During the lowering movement, thepiston 21 returns into its starting position. Thedifferential piston 24 returns only until thesmall piston surface 26 enters into its cylinder bore because the liquid trapped in the annular space cannot escape through thechannel 30. Now, the reversal into the position causing the lifting movement is effected, namely by thesmall piston 29 in accordance with FIG. 3 and by thespring 33 in accordance with FIG. 4, because the liquid pressure in thecavity 6 drops. The shifting of theplunger 7 under the influence of thesmall piston 29, and the shifting of thepiston 32 under the influence of thespring 33 in the embodiment of FIG. 4, results from the diflerential pressure acting upon these small pistons due to the pressure drop occurring incavity 6. This pressure drop incavity 6 results from the fact that less fluid flows intocavity 6 from the chamber betweenpistons 24 and 26 than was previously accepted fromcavity 6, due to the stopping of thepiston 24 at the location determined by the entering of thepiston 26 into its cylindrical bore. Thus, the introduction of a lesser amount of fluid intocavity 6 results in a lowering of its pressure permitting the shifting of theplunger 7, or thepiston 32, before the initial position of theram block 3 is reached. After reversal has been effected, the annular space of thedifferential piston 24 is drained via the nowopen line 30 into thecavity 6 and thebores 11 are opened.

The upper point of reversal may be varied by adjusting theabutment member 28.

In accordance with FIG. 4 theplunger rod 7 can be axially displaced by means of the adjusting screws 31 whereby the lower point of reversal is adjusted.

What we claim is:

1. A double action ram adapted to be supplied at a substantially constant rate of delivery of pressurized medium comprising, in combination, a ram housing having a cylinder defined therein, a piston movably mounted in said cylinder and including first and second oppositely related faces, said first face having a smaller area than said second face, a ram block mounted on said piston, an axially extending chamber defined in said piston, a tubular plunger mounted on said housing located within said chamber and slidably sealed with respect thereto and having an inlet communicating with said chamber and an outlet, a pressurized fluid supply conduit communicating with said first piston face, a passage defined in said housing between said piston second face and said supply conduit, a valve within said passage controlling fluid flow therethrough, piston reversing control means communicating with said plunger sensing the pressure within said piston chamber as said piston is axially translated relative to said plunger selectively positioning said valve, and an exhaust conduit selectively communicating with said piston second face.

2. In a double-acting ram as inclaim 1 wherein said piston reversing control means includes a differential pressure piston mounted in said housing in communication with said plunger outlet.

3. In a double-acting ram as inclaim 2, biasing means biasing said differential pressure piston.

4. In a double-acting ram as inclaim 1 wherein said valve is mounted on said plunger.

5. In a double-acting ram as inclaim 4, means mounting said plunger on said housing for limited axial movement relative thereto.

6. In a double-acting ram as inclaim 1, a control piston slidably mounted in said housing communicating with said plunger, said valve being mounted on said control piston.

7. In a double-acting ram as inclaim 6, means adjustably fixing said plunger to said housing.

8. In a double-acting ram as inclaim 1, a first compressed gas accumulator communicating with said supply conduit and a second compressed gas accumulator communicating with said exhaust conduit.

References Cited UNITED STATES PATENTS 2,182,059 12/1939 Schwartz 60-51 3,322,038 5/1967 Dobson 9130O 3,353,352 11/1967 Gardner 6051 FOREIGN PATENTS 845,069 8/1960 Great Britain.

15 PAUL E. MASLOUSKY, Primary Examiner US. Cl. X.R.

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