US3568592A

US3568592A - Power hammer

Info

Publication number: US3568592A
Application number: US807624A
Authority: US
Inventors: Pavel Harvanek
Original assignee: VYZKUMNY USTAV TVARECICH STROJ
Current assignee: Vyzkumny Ustav Tvarecich Stroju a Technologie Tvareni; VYZKUMNY USTAV TVARECICH STROJ
Priority date: 1968-03-18
Filing date: 1969-03-17
Publication date: 1971-03-09
Anticipated expiration: 1988-03-09
Also published as: GB1207785A; DE1913255B2; FR2004154A1; DE1913255A1

Abstract

In a power hammer wherein work located on an anvil is acted upon by a ram located over the anvil an upper piston-and-cylinder means coacts with the ram to lower the latter along a driving stroke by way of a gaseous fluid under pressure and to raise the ram back to its starting position along its return stroke by way of a hydraulic fluid under pressure. A frame means which carries the anvil also carries part of this upper piston-and-cylinder means, while another part thereof is operatively connected with the ram. Beneath the frame means the foundation carries part of a lower piston-and-cylinder means which is operatively connected with the frame means for raising and lowering the latter. A conduit provides communication between the hydraulic fluid of the upper piston-and-cylinder means and the lower piston-and-cylinder means. A control valve is provided in the conduit to open the latter so that when the gas drives the ram downwardly the hydraulic fluid under pressure will flow through the conduit from the upper piston-and-cylinder means into the lower piston-andcylinder means to raise the frame means, and the anvil therewith, simultaneously with the downward movement of the ram.

Description

United States Patent [72] Inventor Pavelllarvanek Zdar nad Sazavou, Czechoslovakia 21 AppLNo. 807,624 [22] Filed Mar.17, 1969 [45] Patented Mar. 9, 1971 7 3] Assignee Vyzkumny ustav tvarecich stroju a technologie tvareni Brno, Czechoslovakia [32] Priority Mai-.18, 1968 [33] Czechoslovakia [31] 2063/68 [54] POWER HAMMER 5 Claims, 1 Drawing Fig.

[52] U.S.Cl 100/269, 72/453 [51] Int. Cl. B30b 1/32 [50] Field ofSearch 100/264, 269, 244; 72/453 [56] References Cited UNITED STATES PATENTS 2,655,002 10/1953 Terhune (100/269UX) 2,914,971 12/1959 KendalletaL- 100/264X 3,103,136 9/1963 Bollar 100/269 3,145,648 8/1964 Mureketal. 100/264 3,353,396 11/1967 Brauer Primary Examiner-Billy J. Wilhite Attorney-Richard Low its return stroke by way of a hydraulic fluid under pressure. A

frame means which carries the anvil also carries part of this upper piston-and-cylinder means, while another part thereof is operatively connected with the ram. Beneath the frame means the foundation carries part of a lower piston-and-cylinder means which is operatively connected with the frame means for raising and lowering the latter. A conduit provides communication between the hydraulic fluid of the upper piston-andcylinder means and the lower piston-and-cylinder means. A control valve is provided in the conduit to open the latter so that when the gas drives the ram downwardly the hydraulic fluid under pressure will flow through the conduit from the upper piston-and-cylinder means into the lower piston-andcylinder means to raise the frame means, and the anvil therewith, simultaneously with the downward movement of the ram.

POWER MER BACKGROUND OF THE INVENTION The present invention relates to a power hammer.

in particular it relates to power hammers of the counterblow type wherein the moving operating components are driven by a hydraulic-pneumatic drive.

in conventional hammers of this type the anvil itself is moved toward the ram by way of a hydraulic coupling of the ram with a piston which actuates the anvil.

ACtuation of the anvil with such conventional structure presents a considerable disadvantage in that for the particular weight of the anvil, its stroke and speed must have a certain relation to the manner of operation of the ram. The less the weight of the anvil, the larger the stroke and the greater the speed thereof, so that a considerable drawback is encountered through the necessity of providing a relatively large stroke and high speed of movement for the anvil because of its relatively small weight with respect to the-ram.

SUMMARY OF THE INVENTION It is accordingly a primary object of the present invention to provide a power hammer which will avoid these drawbacks.

More particularly, it is an object of the invention to provide a power hammer which will increase the weight of the structure which moves upwardly, while the ram moves downwardly along its working stroke, to such an extent that a maximum weight is achieved resulting in the possibility of achieving the desired results with a relatively slow speed and a relatively small stroke for the upwardly moving structure.

In addition, it is an object of the invention to provide a construction which will accomplish this result with simple reliably-operating components which are interconnected and which operate in a simple fully reliable manner to achieve the desired results.

In accordance with the invention, the ram is driven downwardly by a gaseous fluid under pressure and upwardly by a hydraulic fluid under pressure which extends beneath a piston which is operatively connected with the ram. The frame of the hammer carries the anvil which is situated beneath the ram, and a lower piston-and-cylinder means is mounted in the foundation and is operatively connected with the frame for raising and lowering the latter together with the anvil. An operating conduit provides communications between the hydraulic fluid under pressure which raises the ram and the I lower piston-and-cylinder means. When this conduit is opened upon downward driving of the ram along its working stroke, the hydraulic fluid under pressure is driven from beneath the upper piston into the lower piston-and-cylinder means to raise the entire frame of the hammer together with the anvil carried thereby so that in this way the mass which is displaced upwardly while the ram moves downwardly is very greatly increased by the weight of the entire frame of the hammer.

BRIEF DESCRIPTION OF DRAWING The invention is illustrated by way of example in the accompanying drawing in which there is schematically illustrated one possible hammer structure having the features of the invention.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring to the drawing in greater detail now, there is schematically illustrated a frame means 1 of the power hammer. This frame means fixedly carries an anvil 20 which is situated beneath a ram 2. Suitable guides are provided for guiding the ram 2 upwardly and downwardly. An upper piston-andcylinder means generally designated 21 is provided for controlling the movement of the ram 2 downwardly along its working stroke and upwardly along its return stroke. This upper piston-and-cylinder means includes an upper piston 3 and an upper cylinder 4. The cylinder 4 is directly carried by the frame means 1 while the piston 3 is operatively connected directly with the ram 2. At least one of these assemblies 3,4 is provided, although a plurality thereof may be provided as well, if desired and required. In a well-known manner, the space within the cylinder d above the piston 3 receives a gaseous fluid under pressure; while a hydraulic fluid under pressure is situated beneath the piston 3 within the cylinder 4. The space within the cylinder 4 above the piston 3 communicates with one or more tanks in which a compressed gas is situated. These pressure vessels are illustrated schematically since they are conventional and controlled in a well-known manner to admit gas under pressure into the upper part of the cylinder 4 when it is desired to drive the ram 2 downwardly along its working stroke.

The structure of the invention includes further a lower piston-and-cylinder means which, as schematically shown in the drawing, includes pistons 5, each piston being fixed to and extending downwardly from the frame means 1, and cylinders 6, each receiving a piston 5 and being fixedly carried by the foundation which is beneath the frame means 1. The cylinders 6 may be embedded in the foundation. The same hydraulic fluid under pressure which is situated beneath the piston 3 is also located within the cylinders 6 to coact with the pistons 5 in a manner described below.

An operating conduit means 7 provides communication between the space beneath the piston 3 within the cylinder, 4 and the cylinders 6 so that through this operating conduit means 7 it is possible for the hydraulic fluid to flow directly from the upper cylinder 4, that is, from the space beneath the piston 3 therein, into the cylinders 6. It will be noted that the cylinders 6 all communicate with each other through a conduit 22 so that the operating conduit 7 need only communicate with one of the cylinders 6, as shown in the drawing.

A control valve means 8 is operatively connected with the operating conduit means 7 for opening and closing the latter. This control valve means may be manually opened and closed or may be electromagnetically actuated in a well-known manner.

A bypass valve means 9 communicates with the operating conduit means 7, bypassing the control valve means 6, so that fluid can flow upwardly through the valve 9 and bypass the valve 8. Thus, while fluid can flow downwardly from the upper to the lower piston-and-cylinder means through the valve 6 when the latter is opened, for instance, manually or electromagnetically, fluid can move from the lower pistonandcylinder means upwardly back into the upper piston-andcylinder means through the bypass valve 9.

A supply conduit means communicates with the operating conduit means 7 between the valve 8 and the cylinder 6 in order to supply hydraulic fluid under pressure into the cylinder 4 beneath 81 piston 3. A valve 11 is operatively connected with the conduit 10 for permitting fluid under pressure to flow upwardly through the conduit 10 into the cylinder 4. The supply conduit means 10 is supplied with fluid under pressure by a pump 12 which has a suction conduit communicating with a reservoir 14 in which the hydraulic liquid, such as a suitable oil, is located. A valve 13 is situated in the suction conduit so that this valve controls the flow of fluid from reservoir 14 into the suction side of the pump 12.

A bypass conduit 16 extends from the pressure outlet of the pump 12 between the latter and the valve 11 to a controlled bypass valve 17 through which the hydraulic fluid is circulated back to the tank 14.

The spaces within the cylinders 6 beneath the pistons 6 communicate not only with the operating conduit means 7 but also with a return flow conduit means 15 which provides communication between the cylinders 6 and the suction inlet of the pump 12 between the latter and the valve 13.

The valves 9, ll, and 13 may be nonreturn check valves permitting the hydraulic fluid to flow upwardly but not downwardly, while the manually or electrically actuated valve 8 can be a nonretum valve permitting the hydraulic fluid to flow downwardly but not upwardly. The valve 17 can be automatically actuated to provide for a flow from the pump 12 back to the tank 14.

The above described power hammer operates as follows:

The pump 12 which operates continuously whenever the hammer is operated sucks the fluid from the reservoir 14 through the valve 13 and delivers the fluid under pressure through the supply conduit means 10 and the valve 11 into the cylinder 4 beneath the piston 3 therein. As a result, the piston 3 moves upwardly to raise the ram 2 up to its top dead center position which is the starting position for the downward driving stroke of the ram. When the ram 2 has reached its top dead center position, an electrical mechanism such as a time relay switch S and which is conventional is automatically actuated to open the valve 17 so that while the pump 12 continues to operate the fluid will simply be circulated back into the tank 14.

ln order to initiate the working stroke of the ram 2, the control valve means 8 is opened so that now the gas under pressure above the piston 3 will drive the latter downwardly while at the same time the hydraulic fluid under pressure can flow downwardly out of the cylinder 4 into the cylinders 6 through the operating conduit means 7. The ram 2 will, thus, move downwardly along its working stroke partly as a result of its own weight and partly as a result of the pressure of the gas acting downwardly on the piston 3. Simultaneously, the frame means 1, as a result of the action of the fluid under pressure which enters the cylinders 6 from the conduit 7, is displaced upwardly by the hydraulic fluid under pressure so that both the frame means 1 and the anvil 20 carried thereby move upwardly simultaneously with the downward movement of the ram 2. Of course, valve 17 closes as soon as ram 2 moves down from its upper dead center position.

When impact on the work has taken place, the frame means 1 will react by moving downwardly so that the pistons displace the hydraulic fluid under pressure through the prefilling conduit 15 into the suction conduit of the pump 12 and, further, through the supply conduit means back into the cylinder 4 beneath the piston 3. In this way, use is made of the energy stored in the raised frame means 1 and all the structure carried thereby, upon raising of the latter, so that the entire weight of the raised frame means 1 is used to at least partly fill the space in the cylinder 4 beneath the piston 3. The bypass valve means 9 also contributes to the return of the hydraulic fluid under pressure from the lower to the upper piston-andcylinder means by automatically opening at the instant of hard impact and rapid return of the ram so that at this time fluid also flows upwardly through the conduit 7 bypassing the valve 8 in order to enter the cylinder 4. Because of the presence of the bypass valve 9, undesirable pressure peaks generated by the violent impact of the piston 3 with the oil therebeneath in the working cylinder 4 in the case of inadequate filling, as the ram 2 moves rapidly back toward its starting position directly after impact, are avoided. Such pressure peaks which otherwise would occur are eliminated by way of the bypass 9 that enables the hydraulic fluid to flow not only through the conduit 10 but also through the conduit 7 to achieve the required rapidity of the supply of hydraulic fluid beneath the piston 3 during the initial very rapid part of the return movement of the ram 2.

If considered necessary the conduit may be provided with a suitable throttling aperture to assure displacement of the fluid from the conduit 7 into the cylinders 6 for raising the pistons 5 rather than displacement of the fluid out of the cylinders 6 through the conduit 15 to the pump 12 during the downward working stroke of the piston 2. Such a throttling means can assure that the entire frame means 1 and the structure carried thereby will be properly raised to coact properly with the downwardly moving ram while upon rebounding downward thrust of the frame means 1 immediately after impact the pressure in the cylinders 6 beneath the pistons 5 is increased at least for a short period to such a great extent that fluid is displaced through the throttling means and the conduit 15 to the pump 12 as well as through the bypass valve means 9 in the manner described above.

I claim:

1. In a power hammer, a ram and an anvil situated therebeneath, movable frame means carrying said anvil for movement jointly therewith, upper piston-and-cylinder means carried in part by said frame means and operatively connected in part to said ram for driving the latter along a downward working stroke with a gaseous pressure fluid and for raising said ram along its return stroke with a hydraulic pressure fluid, lower piston-and-cylinder means carried by a foundation beneath said frame means and operatively connected with said frame means for raising and lowering the latter, operating conduit means providing communication between said lower piston-and-cylinder means and the hydraulic fluid of said upper piston-and-cylinder means, and control valve means operatively connected with said conduit means for opening the latter to provide for flow of the hydraulic fluid from said upper to said lower piston-and-cylinder means for raising said frame means and anvil while said ram is driven downwardly by said upper piston-and-cylinder means.

2. The combination of claim 1 and wherein a bypass valve means communicates with said operating conduit means bypassing said control valve means for directing hydraulic pressure fluid from said lower back to said upper piston-andcylinder means for at least partially returning said ram upwardly to its starting position directly after impact on the work by the downwardly moving ram and anvil carried by the upwardly moving frame means.

3. The combination of claim 1 and wherein said upper piston-and-cylinder means includes a cylinder carried by said frame means and a piston operatively connected to said ram and movable in said cylinder, said cylinder having a space beneath said piston in which is located the hydraulic fluid under pressure which communicates through said operating conduit means with said lower piston-and-cylinder means, and the space within said cylinder above said piston being adapted to accommodate a gaseous fluid under pressure.

4. The combination of claim 1 and wherein a supply conduit means communicates with said operating conduit means at a location between said control valve-means and said upper piston-and-cylinder means for supplying hydraulic fluid under pressure to the latter, pump means communicating with said supply conduit means for pumping hydraulic fluid under pressure thereto, suction conduit means leading into said pump means for delivering hydraulic fluid thereto, and connecting conduit means leading from said lower piston-and-cylinder means to said suction conduit means so that during downward movement of said frame means part of the hydraulic fluid displaced out of said lower piston-and-cylinder means will flow into and through said pump means along said supply conduit means to said upper piston-and-cylinder means.

5. The combination of claim 1 and wherein said lower piston-and-cylinder means includes stationary cylinders carried by the foundation and pistons respectively fixed to said frame means and extending therefrom downwardly into the latter cylinders.

Claims

2. The combination of claim 1 and wherein a bypass valve means communicates with said operating conduit means bypassing said control valve means for directing hydraulic pressure fluid from said lower back to said upper piston-and-cylinder means for at least partially returning said ram upwardly to its starting position directly after impact on the work by the downwardly moving ram and anvil carried by the upwardly moving frame means.

4. The combination of claim 1 and wherein a supply conduit means communicates with said operating conduit means at a location between said control valve means and said upper piston-and-cylinder means for supplying hydraulic fluid under pressure to the latter, pump means communicating with said supply conduit means for pumping hydraulic fluid under pressure thereto, suction conduit means leading into said pump means for delivering hydraulic fluid thereto, and connecting conduit means leading from said lower piston-and-cylinder means to said suction conduit means so that during downward movement of said frame means part of the hydraulic fluid displaced out of said lower piston-and-cylinder means will flow into and through said pump means along said supply conduit means to said upper piston-and-cylinder means.