US2845900A - Mechanical hammer - Google Patents

Description

MAKOTO USUKI MECHANICAL HAMMER 2 Sheets-Sheet 1 INVENTOR d 16/0 6% (114 ATTORNEY Aug. 5, 1958 Filed Feb. 1, 1955 I mi? 57% a F FIE. 4.

Aug. 5, 1958 MAKOTO USUKI MECHANICAL HAMMER 2 Sheets-Sheet 2 Filed Feb. 1, 1955 INVENTOR ATTORNEY United States Patent MECHANICAL HAMMER Makoto Usuki, Fukuoka City, Japan Application February 1, 1955, Serial No. 485,485

Claims. (Cl. 121-30) The present invention relates to a method and apparatus for driving statically such objects as piles, rivets, or the like by utilizing reactional force arising when sudden movement is started.

The invention has for its object to drive statically piles, rivets, drill or other objects utilizing no impulsive force.

Another object of the invention is to drive piles, rivets,

or other objects entailing no disadvantageous troubles such as noises, vibration, and so on in the driving operation by means of a cheap and simple arrangement.

A further object of the invention is to drive piles, rivets, or other objects causing no damage to piles, rivets, or the like.

A still further object of the invention is to carry out easily and quickly the driving operation of piles, rivets, or other objects.

Other objects, features and advantages of the invention will be apparent from the following description.

Apparatuses heretofore in use for driving piles, rivets, or other objects, such as a drop hammer, a pneumatic hammer, a steam hammer and the like, have primarily employed a ram type impact tool and produced instantaneously large thrust by the impact of the ram, such impulsive force being utilized for the purpose of pile driving. These pile-driving means, however, not only make noises due to exhaust and impact but also entail severe vibration and are sometimes in danger of even causing damage to piles to be driven. The present invention has improved pile-driving methods heretofore followed to remove defects involved therein, utilizing the reaction of inertia arising in a weight when it starts a sudden upward movement away from the top of a pile and thereby pressing the pile top to push or drive the pile statically.

The present invention is characterized in that it utilizes quite effectively the pressure and expansion speed of a highly-compressed gas and the pressure of a high pressure liquid to each other to produce instantaneously large, effective pressure and by means of the pressure thus produced makes a body of large weight at rest start movement acceleratively so as to produce instantaneously large,

effective thrust or pressing force relative to the impulsive force by the reaction of inertia arising in the weight in the movement thereby to drive statically piles, rivets, or

other objects.

The present invention relates also to apparatuses for carrying out the method as above described for driving such objects as pile, rivets, or the like.

Further, the present invention is applicable for forging and stamping iron and steel materials or their works in place ofthe forging machine.

In order that the invention may be clearly understood, it will now be described with references to the accompanying drawings.

The accompanying drawings illustrate by way of example only apreferred embodiment of an apparatus for carrying out the method according to the present invention, and wherein:

Fig. 1 is a front view of the above embodiment;

Fig. 2 is a longitudinal sectionalview of the same;

Fig. 3 is a horizontalsection taken on the line IIIII'I of Fig. 2;

Fig. 4 is a horizontal section on the line IV-IV of Fig. 2;

Fig. 5 is an enlarged view, partly in section, showing the main valve of the apparatus, with a part broken away, and

Figs. 6 to 11 are each a longitudinal sectional view, illustrating respectively a successive position of the automatic valve in operation.

Referring to the drawings: the interior of the upper portion It of the casing of the apparatus is divided by a first piston 5 into an upper first chamber. or pneumatic cylinder 7 and a lower portion including a first oil pressure chamber (second chamber) or hydraulic cylinder 8 and a valve means for feeding pressure oil to a pasasge 9. Compressed gas or other non-combustible gas under pressure and an adequate amount of cylinder oil are fed through an inlet hole (44) for compressed gas (Figs. 1 and 2) into the cylinder 7. A second oil pressure chamher (third chamber) or hydraulic cylinder 30 in the lower portion 2 of the casing of the apparatus has a second piston 31 inserted thereinto from below and is provided on its front side with oil discharging- means 35 and 32. The second piston 31 carries at itsend projecting from the casing 1, 2 (see Fig. 1) an engaging member such as a cap or pressure plate 45. The head cover 3 of the upper portion 1 of the casing is connected by bolts 4 to the lower portion 2 having an inlet pipe 42 to supply pressure oil to the first hydraulic cylinder 8. Inside of the center of the head cover 3 is a recoiling cylinder 17,

ton 5. The main valve 18 is conical in its lower end and has a cylindrical part 19 a little smaller in diameter than the top of the lower conical part, thus forming a shoulder 20 to fit tightly a valve seat 21 arranged within the top of the second hydraulic cylinder 30 in the lower portion 2. The top of the valve seat 21 is ring-shaped, extending into the upper portion 1 to be capable of tight contact with the lower face of the first piston 5, and thusforms the passage 9 between the first hydraulic cylinder 8 and the second hydraulic cylinder 30. In the center of the main valve 18 is provided an oil hole 43, in which is disposed a spring 26 and on it a residual oil discharge valve 24, the top of which is formed with a piston 25. Oil discharging ducts 23 directed toward said part being provided in the top part of the main valve within the passage. An oil duct 29 bent at its top is formed above the cylinder 27 in the main valve 18 and another oilduct 28, which communicates with the duct 29 when the main valve 18 is in its upper position, is arranged in the .first piston 5, with its lower end opening into the first hydraulic cylinder 8. A safety valve consisting of avalve body 32, a spring 34 and an adjuster (or adjusting screw) 33 is provided above an oil-discharging safety valve consisting of valve bodies 35, 36, a spring 37 and anadjuster (or adjusting screw) 38.

An oil discharging safety valve is provided on the closing thereby the second hydraulic cylinder. If pressure in the second hydraulic cylinder 30 drops to that set in advance, the spring 37 urges the valve bodies 35 and 36 (discharging valve) to the left. As a result, the oil in the second hydraulic cylinder 3% is caused to be discharged into the discharging oil vessel 39 through the valve seats of said valve bodies 35, 35 and oil holes formed in the cylindrical valve housing surrounding these valve bodies 35 and 36. Y

The operation of the automatic control of the apparatus will now be described with reference to Figures 6 to 11. Fig. 6 shows the main valve 18 in the position assumed before the start of operation. In this position the passage 9 is closed, the air pressure in the compressed air cylinder 7 being balanced with that in the inner cylinder 11 by-the check valve 12. In Fig. 7, a small quantity of driving oil is forced into the first oil pressure cylinder 8, through the inlet pipe 42 by a pump (not shown) causing the first piston to commence its upward movement against the gas pressure in cylinders 7 and 11 acting upon the upper surface of the piston 5, whereby its lower surface is lifted from the upper opening of the passage 9, thus transmitting the oil pressure in the first cylinder 8 to the inside of the passage 9. The oil pressure transmitted to the inside of the passage 9 acts upon the pressure-receiving surface in the upper portion of the main valve 18 to urge the valve downwardly. Since the main valve 18 and the recoiling piston 16 are connected to the common rod 10, and since the cross-sectional area of the passage 9 is larger than that of the recoiling cylinder 17 and thus the pressure acting on the main valve 18 is larger than that on the piston 16, the valve 18 is lowered by the pressure in the nozzle 9, together with the cylinder 11 and the recoiling piston 16. However when the valve has descended a certain predetermined distance, the cylinder 11 prevents further descent of the valve. The reason for this can be found in the fact that when the cylinder 11 descends together with the main valve 18, the volume within the cylinder 11 is reduced in proportion to the extent of the descent so that the pressure of the compressed air within the cylinder 11 is raised until it prevents any further descent of the cylinder 11 and accordingly of the main valve 18 connected to the cylinder 11 by the rod 10. In this case, the shoulder 20 of the valve 18 and the valve seat 21 are separated a certain distance from each other, creating some clearance therebetween, but the close contact between cylindrical part 19 of the valve 18 and the valve seat 21 maintains the nozzle 9 in perfect closure and no leakage of oil into the cylinder 30 occurs. Pig. 8 shows the first piston 5 which has been lifted by the increase of the oil quantity in the first hydraulic cylinder 8 until its head 6 comes in contact with the lower end of the valve rod 15. In this stage the main valve 18 is back in its upper position with the ascent of the first piston. As described above, in the states as shown in Figs. 7 and 8, the main valve 18 is downwardly intensely urged by the internal pressure of the pressure oil being forced into the first oil pressure cylinder 8 above said valve 18, while on the other hand the main valve 18 is subjected to two upwardly directed forces by the piston 16 provided on the head of the valve rod and by the compressive resistance of the compressed air in the cylinder 11.

Let the downwardly acting force due to the pressure in the first hydraulic cylinder=F Let the upwardly acting force by the piston 16=F and Let the upwardly acting force due to the compressive resistance of air within the cylinder 11=F In the cases of Figs. 7 and 8 1 2+ 3 that is, the sum of forces acting upwardly on the main valve 18 is larger than F and hence the valve does not descend. Thus the main valve 18 is tightly closed.

In the case of Fig. 9, since the upper part 6 of the first piston forces the valve stem 15 upwardly to open the exhaust valve 13 provided on the cylinder 11, the air compressed within the cylinder and urging the latter upwardly is exhausted through said exhaust valve 13 into the upper compressed air chamber 7, thus causing the force F acting upwardly on the cylinder 11 to disappear. Therefore, the relation of the forces acting on the main valve changes to that is, the force acting downwardly comes to predominate and causes the main valve 1% to descend together with cylinder 11. In Fig. 10 the main valve 18 is shown opened with the oil accumulated in the first oil pressure cylinder 8 forced into the second oil pressure cylinder 39 through the agency of the first oil pressure piston 5 under the pressure within the compressed air chamber 7. In this case, since the lower surface of the first oil pressure piston 5 tightly closes the upper end of the passage 9, F disappears and that portion of the internal pressure within the compressed air chamber 7 which acts on the main valve 13 is the sum of F i. e., the force acting on the piston 16 and F i. e., the force urging the valve rod 10 downwardly (F =cross-sectional area of the valve rod 16X pressure of the compressed air).

Further, since F F the main valve 18 readily starts to return to its upper position while drawing air through the suction valve 12 into the cylinder 11. In Fig. 11 the point has been reached in which the ejection of the pres sure oil out of the first hydraulic cylinder 8 into the cylinder 30 has ceased as the first piston 5 has blocked the passage 9. The pressure prevailing in the cylinder 7 acts now on the piston 16 in such a manner that it is pressed upwardly, resulting in the upward movement of the valve 18 so as to bring the top of the cylindrical part 19 of the valve in contact with the lower end of the valve seat 21. The residual oil is then discharged through the oil discharging ducts 23 to the oil hole 43, but when the main valve is so raised so that the oil duct 29 therein communicates with the oil duct 23 in the first piston, the oil pressure in the first oil pressure cylinder 8 is transmitted immediately to the cylinder 27 to close the valve 24- and thereby to break the connection between oil discharging ducts 23 and 43 so that the passage 9 is closed completely by the main valve. The cycle or process of operation is thus completed and the arrangement shown in Fig. 6 is restored in preparation for elfecting the operation again in the same manner. Further, the main valve 18 may be arranged to slide a certain distance along a portion of the inner wall of the passage 9 in order to prevent the shoulder of the valve 18, even in the position of Fig. 7, from clearing the valve seat 21.

In operation, first of all, non-combustible gas under pressure, for example, compressed air and an adequate amount of cylinder oil are filled through an inlet hole 44 for compressed gas into the cylinder 7, and the bottom of the second piston 31 formed with a cap 45 or other suitable pressure plate is brought into contact with the top of a pile or the like object to be forged, or an object to be pressed, while maintaining the stability of the driving body by adequate guide rails or other suitable means. A flow of driving oil is continuously forced into the first oil pressure cylinder 8 through a high pressure hose or piping connected from an oil pressure pump (not shown) to the inlet opening 42, whereby the second piston 31 projects outwardly and effects accurately operative strokes with a certain acceleration to apply an instantaneously powerful static pressure repeatedly to the body to be pressed. The object of applying pressure is thus readily attained. Under these circumstances, the driving body of the apparatus is also pushed back upwardly by the reactional force against its own pressing action on the body to be pressed and hence retracts acceleratively. This is due to the fact that the driving body of the apparatus has no obstacles other than its own inertia to prevent its retracting movement and thus is in the position that it can retract freely by any external force.

The principle applied in this invention in which, as described above, powerful static pressure can be applied to the body to be worked with the driving body held in the position allowing free retracting movement thereof pertains to an extremely simple theory completely conforming to the first law of Newton expressed in the formula F=mz, as in the case of striking. Thus the action of the pressing force of the present invention is expressed by the above formula, wherein:

F=(Oil pressure in 2nd oil pressure cylinder) (crosssectional area of the same cylinder) =pressure,

m=Mass of retracting driving body, and

a=Acceleration of the driving body when retracting.

Accordingly, the driving body and the body to be worked are separated while applying external force F to each other according to the principle of action and reaction, with the piston 31 interposed therebetween, so that the purpose of applying statical pressure to the object to be worked can be attained by keeping the intensity of the given external force F constant at a sufficiently high level until the end of the operative stroke of the second piston 31.

Furthermore, the relationship of compressed air to the present invention will now be described.

A feature of the present invention resides in that, as described above, a very large acceleration is imparted when the second piston 31 effects operative movement.

Thus, for causing the second piston 31 rapidly to effect operative movement, the forcing of driving oil into the second hydraulic cylinder 30 must be effected extremely rapidly. However, since the oil delivery of the hydraulic pump in a unit time is so small the aforesaid object cannot be attained. Moreover, intermittent oil delivery into the second hydraulic cylinder 30 is also difficult. Therefore, in accordance with the present invention, the driving oil incessantly delivered from the hydraulic pump is accumulated within the first oil pressure cylinder 8 for a certain period of time until the amount of said driving oil accumulated reaches a certain predetermined level, after which the main valve 18 is opened so that the force of the compressed air may be utilized as a powerful pneumatic spring to instantaneously deliver the said driving oil into the second oil pressure cylinder 30, thereby imparting the second piston 31 an accelerative operative movement.

To summarize the above operation, the pneumatic spring in the pneumatic cylinder 7 is compressed by the driving oil forced into the first oil pressure cylinder 8, thereby storing a large amount of energy during the process of such compression. Said energy thus stored up in a certain period of time required is transformed or converted in quite a short time into the energy of work by the rapid expansion of the pneumatic spring 7, thereby producing an instantaneously powerful pressing force during the process of the rapid transformation of the stored energy into the work of energy.

The purpose of providing the compressed air chamber 7 lies in this point.

As above described, according to the present invention, smooth operation can be effected quietly, safely and with ease, by a method entirely different from striking methods of heretofore known impact tools, at the same time completely eliminating the vibration due to impact and the accompanying sound of impact as well as any possible damage and deterioration of the material of the object to be pressed.

What I claim is:

1. In a mechanical hammer the combination of: a casing having a first chamber, a second chamber and a third chamber capable of communication with said second chamber, a first piston member slidably arranged between said first and second chambers and separating same, said first chamber being capable of holding a compressed gaseous medium, inlet means for supplying hydraulic fluid to said second chamber, a second piston member slidably arranged in said third chamber and carrying an engaging member capable of engagement with a work, valve means arranged between said second and third chambers and being responsive to the pressure in said first and second chambers, and controlling means for controlling the opening and closing of said valve in dependence on the respective pressures in said first and second chambers, said controlling means comprising a cylinder member arranged within said first chamber and being operatively connected to said valve means, said cylinder member in conjunction with said first piston member, defining a fourth chamber capable of holding a compressed gaseous medium, a portion of said first piston member being slidably engaged with said cylinder member, a check valve arranged between said first and fourth chambers, and a further valve between said first and fourth chambers, said portion of said first piston member being capable of opening said further valve.

2. In a mechanical hammer the combination of: a casing having a first chamber, a second chamber and a third chamber capable of communication with said second chamber, a first piston member slidably arranged between said first and second chambers and separating same, said first chamber being capable of holding a compressed gaseous medium, inlet means for supplying hydraulic fluid to said second chamber, a second piston member slidably arranged in said third chamber and carrying an engaging member capable of engagement with a work, valve means arranged between said second and third chambers and being movable between a first posi tion and a second position, the communication between said second and third chambers being interrupted by said valve means in said first position, the communication between said second and third chambers being established in said second position, said valve means comprising a seat and a valve body, a connecting member, said connecting member carrying said valve body and a third piston member slidably arranged in said first chamher, a cylinder member mounted on said connecting member in said first chamber, said cylinder member defining in conjunction with said first piston member a fourth chamber capable of holding a compressed gaseous medium, a portion of said first piston member being slidably engaged with said cylinder member, a check valve arranged between said first and fourth chambers, and a discharge valve between said first and fourth chambers, said first piston member being slidable between a first position and a second position, the communication between said second and third chambers being blocked by said first piston member in said first position, and said discharge valve being opened by said portion of said first piston member in said second position.

3. A method for applying statical pressure to an object by utilizing the pressing force of a piston of a ham mer which is operated acceleratively and provided in the body of the hammer with a pressure accumulating means divided into a cylinder holding compressed gaseous medium and an oil pressure cylinder by a piston member characterized by a piston-cylinder assembly and a valve means effecting automatic control which operates to intermittently deliver a high pressure liquid, incessantly forced into and accumulated in said oil pressure cylinder, into.

said piston-cylinder assembly each time when said liquid of a predetermined quantity is accumulated, so as to operate acceleratively the piston, the pressing force there- 7 of being utilized to apply a large effective static pressure corresponding to a striking force to a pile, an object to be forged, or the like.

4. A method for applying a statical pressure to an object by utilizing a pressing force of a piston of a hammer which is operated acceleratively, characterized in that an automatic control valve is automatically operated by the utilization of the pressure variation of a fluid under pressure in a cylinder attached together to the valve rod of said valve in a cylinder holding compressed gaseous medium of a pressure accumulating means and of ti action of a piston secured to the top of said valve rod of said valve.

5. A method for applying a statical pressure to an object by utilizing a pressing force of a piston of a hammer which is operated acceleratively, characterized in that the opening and closing operation of an automatic control valve is effected by alternatively reversing the size of two opposing forces, that is, a force generated by the pressure acting in a cylinder secured rigidly to the valve rod of the said valve in a cylinder holding compressed gaseous medium of a pressure accumulating means and also due to the pressure on a piston which is secured together to the top of the valve rod of the automatic control valve in such a manner as to be subjected to the action of the pressure within the compressed air cylinder, and a force due to the oil pressure in an oil pressure cylinder of the pressure accumulating means.

References Cited in the file of this patent UNITED STATES PATENTS

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