US3446293A - Pile driver - Google Patents

Description

C. L. GUILD ET AL PILE DRIVER May 27, 1969 Filed Dec. 28, 196e ATTORNEYS 2 N 0 3 6 0 A .I M m ,M 2 .I 2 .0 Y m G IIf 2 L B mi@ m mw III). D o o o o M l :sh w MIJ .Il lIlIlfsirrllfLW F 2 3 3 n 2 a w W 0 I. I. m @www III mw E @F I( wk m d F L .IWIM w IW, IH. I I .I In? 3 ,IIIII4 SI, 2 I 7 4 e III 2 IIIIII I I I Q IIIVII IIIIII e II N\\\. I I I ,II. O .E- xr May 27, 1969 c. L. GUILD ET AL 3,446,293

PILE DRIVER Filed Deo. 28, 1966 Sheet of 2 FIGIO FOR TRAVDlsTANoE DIST.

F l G. 5 F IG. 5A

83 FORCE IMPACT TRAVEL DISTANCE 6 F l G. 7

INVENTORS F G' 9 CHARLES l.. GU|LD BYWILLARD B. GOODMAN ATTORNEYS United States Patent O U.S. Cl. 173-131 2 Claims ABSTRACT OF THE DISCLOSURE A pile driving cushioning device for use for driving a member into the earth which may be readily attached to a driving ram and which includes a plurality of cushioning members which may be adjustable to vary the stiffness of the assembly and provide proper balance.

Background of the invention It is very common to utilize hammering devices of various types for driving piles into the earth and to place between the top of the pile and the hammering device some sort of a cushion block to absorb the'energy and prevent undue damage to the hammer and also to the top of the pile.

Hammering devices themselves are numerous, some being operated by compressed air or steam supplied from an external source and also there are diesel and 4drop hammers. Not only has wood been used as a prior cushioning device, but also coil cable, phenolic and aluminum discs have even been utilized between the top of the pile and the bottom end of the ram so that the peak compressive stresses that occur will not damage the top of the pile and/or the hammer. An example of a form or prior art device is shown in the Kinneman Patent 2,184,745 where a spring in the form of a Belleville washer has been utilized as the cushoining device and also illustrates the prior art scheme of utilizing a block of wood. One of the objectionable features of the prior art devices has been the noise which is generated and it is very desirable, therefore, to have a device which would be much quieter in operation. Further, it is rather desirable to have a device which will store energy and this stored energy can be released for the actual driving of the pile into the ground.

Summary This invention provides a cushioning device for pile driving which utilizes both an adiabatic compression of a gas which results in nonlinear spring action along with linear spring action or uses the two items individually to provide an improved structure of cushioning device for insertion between the ram end of a conventional hammer and the top of a pile. In the devices of this invention the load that is being imparted to the pile is not so abrupt as to damage the top of the pile, it being moditied by the particular form of cushioning devices of this invention.

Description of the drawings FIG 1 is a sectional view of the lower portion of the hammering device constructed in accordance with our invention;

FIG. 2 is a partial elevational view of the device constructed in accordance with our invention with parts broken away and showing the ram in the extreme lower position and at the point which maximum force is delivered to the driven member;

FIG. 3 is a partial elevational view with parts in section showing a modied form of drive head;

ICC

FIG. 4 is a series of diagrammatic views illustrating the operation of our device;

FIGS. 5, 5A and 7 are graphs of the performance of the device; and

FIGS. 6, 8, 9 and 10 are sectional views of modified forms of the device.

Referring to the drawings, particularly FIGS. 1 and 2, 30 designates the member to be driven. A driving head 22 has a downward extension 26 provided with an internal bore 27 which is threaded as at 28 to be screwed onto the top of the member 30. This driving head is anged as at 23 and receives a casing 10 into which the boss 24 projects. An O-ring 25 in a recess in the boss snugly lits the inner surface 12 of the cylindrical casing providing a seal. A ange 11 extends outwardly from this casing and mates with the flange 23 of the driving head 22 and is secured thereto by a plurality of bolts 32. This casing is of a size to slidably receive the piston or ram 13 which may be lifted and dropped by some conventional means such as shown in FIG. 4 from and toward the driving head 22. The piston 13 is provided with a plurality of piston rings 14 to have snug engagement with the inner surface 12 of the casing. Air or any gas may be trapped between the boss 24 and the end of the piston or ram 13 as it descends in the casing 10. The volume of air may be varied by the provision of a number of rows of apertures, there being shown rows of apertures 16, 17, 18 and 19. An outer sleeve 20 is slidably received on the exterior of the casing 10 and may be slid upwardly from the position illustrated in FIGS. 1 and 2 of the drawings to a position to control the location of communication between the outside of the casing 10 and the interior thereof -by partially or completely cutting olf one or more of the rows 16 and 17, 18 and 19 of the apertures.

By this arrangement as the ram or piston descends, an air cushion is developed in the casing beneath the piston or ram which is so designed as to volume that the resistance due to the air cushion is equal to the force developed by the mass of the ram and its acceleration when descending so that the ram will never hit the driving head 22, but rather the energy which is stored in the compressed gas of this resilient cushion will be such as to force the driving head downwardly and consequently the member downwardly into the medium in which it is to be driven, and by reason of this cushion no striking noise is heard but rather a quiter action of driving the member is provided than has heretofore rbeen known in hammering devices.

Referring to FIG. 3 of the drawings, a slightly modied form of drive head has been shown. In this embodiment the drive head 22' is rovided with a lower extension which is recessed in the form of a spherical surface 35 and clamped below the flange 23 is a flange 37 of a lower guide sleeve 38. Located within the bore of the sleeve 33 is an auxiliary spherical head member 40 having a lower cylindrical plate portion 41 which rests on the top of a member 42 to be driven =by the provision of the head 22. The force of the blow that is exerted on the drive head 22 will be distributed more evenly over the entire end surface of the driven member 42 and it will prevent any concentration of forces at one edge of the end surface.

The operation of the device shown in the drawings is schematically illustrated in FIG. 4. After the drive head is placed on the member to be driven, for example, a cylindrical pipe or pile, an engineering decision is made as to the amount of force which the device is to exert on each stroke. If a large value of force is desired, all of the ports are left open as shown in the drawing but if a lesser force is desired, then the sleeve 20 is moved upwardly to either partially or fully cover one or more of the rows of the ports 16, 17, 18 or 19. The piston is raised by a suitable means which is illustrated in simplest form, FIG. 4, by means of a cable 15 that is guided over a winch drum 45. At the top of the stroke and after the piston has been raised a predetermined distance above the lowermost row of ports or apertures 16, 17, 18 or 19 the cable is released permitting the piston a free fall. At this point it will be realized that during the upward travel of the piston or ram 13 air has been drawn in through the rows of apertures and now on the downstroke a certain amount of this air is exhausted and the -piston travels downwardly until the piston rings 14 thereof seal the lowermost row of apertures that have been left open. At this point the air that is within the bore 12 below the lower end of the piston 13 is compressed and the piston 13 continues its downward stroke based on the acceleration it has attained, all of the air below the piston being compressed to act as a cushion. With the design constants being proper the piston 13 does not contact the upper edge of the drive head 22 but there is created a cushion of air of several thousand pounds per square inch pressure and the resultant of this action of the piston traveling downward and compressing the air will exert a force on the drive head through this air cushion and drive the member 30 into the ground or whatever other medium is provided without any solid contact. Due to certain elasticity in the driven member 30 there will be effectively an overtravel of the drive head which will spring back for a partial distance in the manner of a sharply damped oscillation.

In the above example the adiabatic compression of the air or gas results in a non-linear spring action. In utilizing a non-linear spring action, such as is created by the pneumatic cushion device, we have a rapid buildup of force as the pressure is increased by the dropping ram. This eiect is illustrated graphically in FIG. of the drawings which is a graph of distance of travel of the ram versus the force exerted thereby. It will be seen by examining this figure that the force that is exerted increases rapidly as the pressure increases by the descending ram. This pressure will of course reach a peak value. A true uncushioned blow type of impact represented in a similar fashion would be substantially as shown in FIG. 5A where a line that is nearly vertical represents a rapid increase in force and resultant stress. By comparing these two diagrammatic views, it will be seen that there is a great similarity in impact when one considers the pneumatic spring cushion device as operating against a straight impact hammer device. Thus, where a large blow is desired for each stroke the pneumatic cushion spring device is a desirable solution to the problem.

FIG. 6 illustrates the adaptation of the mechanical spring cushioning theory to any conventional type hammer by the use of a mechanical spring. For example, one such hammer is illustrated in the U.S. Patent 2,004,180 which patent is illustrative of a pneumatic type hammer in which a ram is driven by some type of a piston means operating as a motor. In FIG. 6, 50 indicates the lower part of the hammer assembly or housing which may take a variety of forms and 51 is the ram that is driven by the motor means in the hammer. To the lower end of the hammer assembly or housing, designated by the numeral 52, there is fastened a cushion block generally designated 54. This cushion block is in two parts, an upper section 55 which is directly secured to the flange 52 by a number of bolts 56 being threadingly received in the block and a lower section 57 is the drive head which rests on the pile or lpiling casing and which is coupled to the upper section through a plurality of rnechanical compression springs 58. To hold the sections together and the springs in location, each of the sections 55 and 57 is recessed as at 59 and 60 respectively which recesses receive the end portions of the mechanical spring 58. Further, bolt means 61 pass centrally through the spring 58. The bolts 61 are provided with heads 62 which are themselves received in counterbores such as -63 and the threaded end of the bolts 61 are received in the upper section 55. The arrangement is such that the bolts 61 serve more or less as alignment means to maintain in alignment the two sections 55 and 57 and further alignment means may be provided if desired at the center of the two sections 55 and 57 as by a loosely received bolt such as 64. The lower section or drive head 57 vmay be shaped as by a recess such as 66 to iit the top end of a wooden pile, a steel I beam or H beam or to a driving clamp or any other suitable shape. In the case of the mechanical spring device, reference is now made to FIG. 7 of the drawing where a graphical representation of the force exerted by the section or drive head 57 for the distance of travel of the upper section 55 is illustrated. At the limit of the upper section travel, impact occurs by direct Contact of upper section 55 and drive head 57. This point shown as impact on FIG. 7. The resultant force and stress increase rapidly as shown by the vertical line and this linear increase of force is useful in some applications as it gives a more constant push to the member being driven.

Referring now to FIG. 8, there is illustrated the adaptation of the pneumatic spring cushion to the end of a standard Vulcan hammer. Utilizing the same reference numerals for the hammer as were applied to FIG. 6, a driving head 70 is provided with a flange 71 which may be bolted to the flange 52 of the Vulcan hammer construction. The drive head 70 is provided with a central bore 72 in which is received a piston 73, the upper end of which may be reduced so as tomake contact with the ram point 51 of the Vulcan hammer. The piston 73 is provided with the usual piston rings 74 to achieve sealing engagement with the bore 72.1Conduit means 75 communicate with the lower end of the bore 72 and in the conduit 75 there is located a check valve means 76. The conduit 75 is adapted to be connected to a source of air under pressure so as effectively to place within the area defined between the piston and the lower end of the bore, a predetermined amount of air under pressure. This serves to act as a return spring means so that the piston 73 will be driven up against the shoulder of llange 52 and should therefore be of a suicient pressure to normally raise the piston 73 against the forces of gravity and friction. From a practical standpoint it is usually desirable to connect the conduit 75 to a constant source of pressure furnished by the usual air compressor, the check valve 76 preventing the return of air to the compressor and damage of this auxiliary apparatus. In all basic respects this embodiment operates the same as the embodiments of FIGS. 1, 2 and 3. Thus as disclosed for the lower end of the drive head 70 may be provided with some type of an adapter recess 77 for connecting and piloting to various types of members to be driven such as cylindrical piles, H beams, I beams and the like.

Referring now to FIG. 9 of the drawings, there is illustrated therein an adapter for attaching to a Vulcan hammer which combines the desirable operation as illustrated in FIGS. 1 to 3 with a mechanical spring return means for the piston, thus obviating the need for external air under pressure. The same reference numerals are used to indicate the Vulcan hammer and with reference to the drawings. The instant embodiment is provided with a two-part housing consisting of an upper part 80 and a lower part or drive head 81. The upper part 80 is provided with a pair of opposed flanges 82 and 83 while the lower part or drive head 81 has an upper flange 84 and a lower nose section 85. The ange 82 of the upper part 80 is bolted to the flange 52 of the hammer and the ilanges 83 and 84 are also bolted together to form a composite unit. A dead-ended bore 86 is formed in the lower housing or drive head 81 and within this bore there is slidably received a piston 87 having piston rings 88 encircling the same for sealing engagement with the wall of the bore 86. A piston rod 89 passes throughl the upper housing 80 and is encircled by a return spring 90,

one end of which abuts a shelf ring 91 in the housing 80, the other end of which abuts a ring 92 that rests against a collar 93 that is iixedly attached to the piston rod 89. The operation of this device is similar to the operation as described in FIGS. 1 to 3 as air will normally enter the port 95 formed in the lower housing or drive head 81 and be compressed by the action of the piston. Venting is provided through a vent port 96 and return action of the piston against the shoulder 82 is had by reason of the spring 90.

Referring now to FIG. l() of the drawings, there is illustrated therein an alternate embodiment to that illustrated in FIG. 8. Specifically in this embodiment there is shown an increase in the piston area without any increase in diameter by in effect providing three separate pistons in parallel. By way of specific example, utilizing the same reference numerals that were applied in FIG. 8, a driving head generally designated 70 may be constructed in a number of separate parts which are suitably bolted together by means not shown and consists basically of an upper ilange section 71 intermediate ring sections 97A, 97B and 97C which receive therebetween piston divider blocks 98A, 98B and have an end member 98C which is provided with suitable adaptation for connecting and piloting the various types of members to be driven. A multiple piston 73' is provided with the usual piston rings 74 which engage the inner surface of the ring members 97A, 97B and 97C. Sealing means 99 are provided on the main stem of the piston 73 to seal the three compression areas from each other and engage inner bores of the divider blocks 98A, 98B and the upper flange 71. Each of the compression areas are connected t0- gether by a bore 75 which in turn has a check valve inserted at the outer connection portion thereof, the check valve being designated by the reference numeral 76. Vent means are provided in each of the piston areas, vent means being designated by the numeral 100, and these vent means serve to permit the pistons to move in an upward direction unimpeded. As in the embodiment of FIG. 8, the conduit 75 is adapted to be connected to a source of air under pressure so as to place underneath each of the pistons a predetermined amount of air which acts as a return spring so that the pistons will be driven upwardly against the ram 51 and in the extreme or for limiting case against the lower surface of the upper head 71. Additionally in this embodiment for purposes of alignment with the ram 51 and distribution of forces therefrom, the upper end of the piston 73' is provided with a spherical seat 35 and an adapter member 22A in a fashion similar to that shown in FIG. 3.

Basically what is being achieved here is that a change in load is being experienced on a pile which creates the so-called driving force. The manner in which this load changes has been illustrated somewhat in the diagrams in FIGS. 5 and 7 which graphically illustrate the difference in a gentle push and a more sudden load change. Of course the sudden load change should not be so severe that it actually damages the top of the pile which is being driven and also create damage to the driving means such as a Vulcan hammer for example. In the pneumatic spring, of course, we have a non-linear situation Where the spring rate increases very rapidly as the chamber gets smaller by the piston decreasing traveling downward. As has been explained before, the steep slope that is shown in the diagram of FIG. 5 is desirable as it approaches that of the steam type hammer of FIG. 5A.

We claim:

1. A cushioning device for driving a member into the earth comprising a drive head, means for attaching the drive head to the member, a ram and cushioning means interposed between the ram and the head comprising a plurality of compressible means to develop a resistance equal to the force developed by the mass of the ram and its acceleration, whereby the member is driven wholly through the cushioning means, said cushioning means comprising a plurality of coil springs, a ram contacting section, said springs circularly arranged about said section and extending between the section and said head and bolts loosely holding said section and said head in alignment.

2. A cushioning device for driving a member into the earth comprising a drive head, means for attaching the drive head to the member, a ram and cushioning means interposed between the ram and the head comprising a plurality of compressible means to develop a resistance equal to the force developed by the mass of the ram and its acceleration, whereby the member is driven wholly through the cushioning means, said cushioning means comprising a plurality of chambers, a plurality of pistons each having piston rings sealingly engaging each chamber, a common piston rod for each piston engaging the ram and means for admitting air into said chambers.

References Cited UNITED STATES PATENTS 845,953 3/1907 Hitchcock 173-131 886,193 4/1908 De Witt 173-131 911,971 2/1909 Gilbreth 173-131 X 2,184,745 12/1939 Kinneman 173-131 2,723,532 11/1955 Smith 173-131 2,948,122 8/1960 Smith 173-131 3,162,252 12/1964 Cobi 173-131 X DAVID H. BROWN, Primary Examiner.

U.S. Cl. X.R. 173-139

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