AU761726B2 - Set of jaws for sheet pile - Google Patents

Description

WO 00/61878 PCT/AUOO/00316 -1- SET OF JAWS FOR SHEET PILE FIELD OF THE INVENTION The present invention relates to a set of jaws for a vibratory hammer used for driving a sheet metal pile into the ground and relates particularly, though not exclusively to such a set ofjaws for gripping a sheet metal pile of between 3-5mm in thickness.

BACKGROUND TO THE INVENTION The mechanics of pile-driving with vibratory hammers are generally well understood. The vibrations generated in the pile to be driven, such as a sheet pile or tubular pile, produce reduced soil resistance in the ground immediately adjacent to the moving surface of the pile. Therefore comparatively low impact forces are required to drive the pile into or withdraw it from the ground. Nevertheless, in the case of sheet metal pile the material of the pile must be capable of withstanding significant driving forces, particularly in hard soil or clay soil in which substantial resistance during pile driving may be encountered.

Over the last ten years or so there has been a trend toward using a thinner sheet metal pile of the order of 3-5mm in thickness, with fold lines incorporated along its length to impart additional rigidity and strength. A problem has been encountered with this type of thin sheet pile in that some weakening or tearing of the sheet metal can occur along the fold lines during or after driving of the pile into the ground. Australian Patent No. 684957 sought to overcome this problem by providing a set ofjaws having multiple faces arranged at relative angular dispositions designed to match the angular disposition of the flat planar surfaces intersected by longitudinal fold lines of a piling panel. By providing multiple faces on the jaws, the vibration is transferred more uniformly down the entire length of the pile.

However, whilst the jaws of 684957 generally operate satisfactorily and help to overcome the particular problem addressed in the patent, other problems may arise in practice. A typical sheet metal pile of thin form comprises a plurality of first and second coplanar flat surfaces and a plurality of first and second diagonal planar surfaces joined by longitudinal fold lines. The set of jaws of 684957 has at most four pairs of planar contacting surfaces PCT/AU00/00316 Received 24 January 2001 2/1 for gripping four corresponding surfaces of the piling panel. However, all four surfaces of the piling panel which are gripped are centrally located, being one of the first and one of the second diagonal planar surfaces and two of the coplanar surfaces adjoining the respective diagonals. There are typically at least two more diagonals and two more of the coplanar surfaces which hang loose and unsupported either side of the jaws of 684957.

Hence, during driving of the sheet pile into the ground there is a tendency for the sheet pile to bow as the unsupported surfaces either side of the jaws tend to distort under pressure from the uneven resistance of the soil, and due to the fact that most of the downwardlydirectioned driving force is being transmitted through the four centrally located surfaces of the panel described above. Furthermore, because the unsupported surfaces tend to flex and move about during lifting of the piling panels into position, it tends to make the handling of the panels more difficult.

SUMMARY OF THE INVENTION The present invention was developed with a view to providing a set of jaws which enable a sheet metal pile to be more firmly gripped during driving of the pile with a vibratory hammer.

According to the present invention there is provided a set of jaws for a vibratory hammer for driving a sheet metal pile into the ground, said set of jaws including a first pair of opposing jaws and a second pair of opposing jaws, said first pair of jaws being spaced a predetermined distance, in a direction transverse to the driving direction, from said second set of jaws and being substantially aligned in a common plane with said second set of jaws, each jaw of each said pair of jaws having a substantially planar contacting surface of elongate rectangular configuration for compressibly gripping said pile at a predetermined planar surface thereof, and wherein said first and second pairs of opposing jaws are mounted in a common mounting plate adapted to be removably fixed to a vibratory hammer, whereby, in use, said pile can be firmly gripped by said set of jaws at two horizontally spaced locations to transmit a driving force to the pile.

Preferably each said pair of jaws comprises a first stationary jaw and a second moveable jaw. Advantageously said moveable jaw is provided with a guide flange along one edge AMEIDED SHIEET

FIPWAU

PCT/AU00/00316 Received 24 January 2001 2/2 thereof, said guide flange assisting with locating said sheet metal piling between said first and second pair of jaws. Typically said sheet metal pile is of folded form having a plurality of first and second coplanar flat surfaces and a plurality of first and second AMDSD HEt Si-sU WO 00/61878 PCT/AUOO/00316 -3diagonal planar surfaces joined by fold lines. Preferably said first and second pairs ofjaws are arranged to grip respective pairs of flat surfaces of one of said plurality of first and second coplanar flat surfaces. Advantageously said predetermined distance between said first and second pairs of jaws is adjustable, to accommodate different types of sheet metal pile.

BRIEF DESCRIPTION OF THE DRAWINGS In order the facilitate a more detailed understanding of the nature of the invention a preferred embodiment of the set of jaws will now be described in detail, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a side elevation of a preferred embodiment of the set of jaws in accordance with the invention mounted on a hydraulic vibratory hammer; Figure 2 is an end elevation of the set ofjaws and hammer of Figure 1; Figure 3 is an enlarged side elevation of the set of jaws of Figure 2 viewed in the direction of arrow C; Figure 4 is an enlarged end elevation of the set ofjaws of Figure 1; Figure 5 is a plan view of the set ofjaws of Figure 1; and Figure 6 is a plan view of the set ofjaws of Figure 5 shown gripping a sheet metal pile.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT Figures I and 2 illustrate a preferred embodiment of a set of jaws 10 in accordance with the invention mounted on a hydraulic vibratory hammer 12. The vibratory hammer 12 is of conventional design and in this case is provided with a coupling 14 for mounting to the arm of an excavator (not shown). Pivotally suspended from the coupling 14 is a support frame 16 on which the hammer 12 is pivotally supported. Frame 16 can be pivoted about a vertical axis A relative to the coupling 14 by means of hydraulic controls. Similarly, the WO 00/61878 PCT/AU00/00316 -4hammer 12 can also be pivoted about a horizontal axis B relative to the frame 16 by means of hydraulic controls. All hydraulic control lines have been omitted from the drawings for clarity. The vibratory hammer 12 is also hydraulically driven. Within a gear case of the hammer a number of eccentric weights are rotated at high speed by one or more hydraulic motors (not shown). The rotation of these weights generates a vertical vibratory force of sine wave form, the frequency of which corresponds to the rotational speed of the eccentric weights. At the base of the hammer 12 the vibrations thus generated are transmitted to the pile via a base plate 18 and the set of jaws 10. The transmission of vibrations from the hammer 12 to the excavator is suppressed by means of special dampers 20 provided between the hammer 12 and the frame 16 (see Figure 1).

The arrangement of the set of jaws 10 is illustrated more clearly in the enlargements of Figures 3 and 4. The set of jaws 10 include a first pair of opposing jaws 22 and a second set of opposing jaws 24 mounted on a common mounting plate 26 by means of a plurality of bolts 28 shown in broken outline. Mounting plate 26 is in turn bolted to the base plate 18 of the hammer by means of four mounting bolts 29. As can be seen most clearly in Figure 3, the first pair of jaws 22 are spaced apart a predetermined distance from the second pair ofjaws 24.

As can be seen most clearly in Figures 5 and 6, each jaw of each said pair of jaws 22, 24 has a substantially planar contacting surface 30 for compressibly gripping a sheet metal pile at a predetermined planar surface thereof. Each pair of jaws 22, 24 comprises a first stationary jaw 22a, 24a and a second moveable jaw 22b, 24b. The moveable jaws 22b, 24b are moveable between a first open position as shown in Figure 5 in which there is a gap of approximately 50mm between the planar contacting surfaces 30 of the jaws, and a second closed position as shown in Figure 6 in which the planar contacting surfaces grip respective predetermined planar surfaces of a sheet metal pile 32.

As shown in Figure 6, the illustrated sheet pile 32 is of folded form having a plurality of first coplanar flat surfaces 34 and second coplanar flat surfaces 36, and a plurality of first diagonal planar surfaces 38 and second diagonal planar surfaces 40. In this embodiment, the first and second pair ofjaws 22,24 are arranged to grip respective flat surfaces of a pair WO 00/61878 PCT/AU00/00316 of the first coplanar surfaces 34. In this regard, the first and second pair of jaws 22,24 are spaced apart a predetermined distance corresponding to the gap between the pair of first coplanar surfaces 34 of the sheet metal pile 32. In this way, the pile can be firmly gripped by the set of jaws 10 to transmit a driving force to the pile during insertion into the ground.

Furthermore, because the sheet pile is being firmly gripped at two spaced locations the force transmitted to the pile via the set of jaws 10 is distributed more uniformly across the width of the sheet pile 32. Also, only a short length of the sheet pile, namely first and second diagonal surfaces 38,40 and respective adjoining second coplanar surfaces 36 of truncated form, are left unsupported either side of the set of jaws 10. Therefore, flexing and/or distortion of the sheet metal pile 32 during insertion is minimised.

Each of the moveable jaws 22b, 24b are driven by an hydraulic ram 42 capable of producing a compressive force of 25 tonne. The planar contacting surfaces 30 of both the stationary jaws 22a, 24a and moveable jaws 22b, 24b are of elongate rectangular configuration, the moveable jaws 22b, 24b being slightly longer in length than the stationary jaws 22a, 24a as can be seen most clearly in Figure 4. Each of the moveable jaws 22b, 24b is also provided with a guide flange 44 provided along one edge thereof as can be seen most clearly in Figures 5 and 6. The primary function of the guide flanges 44 is to assist with locating the sheet metal pile 32 between the first and second pairs of jaws 22, 24 so that the pair of first coplanar surfaces 34 of the sheet pile 32 are correctly aligned with the planar contacting surfaces 30 of the respective first and second pairs of jaws 22, 24.

When the jaws are in the closed position as shown in Figure 6, the guide flanges 44 do not engage with the diagonal surfaces of the sheet pile 32, and therefore are not in force transmitting contact therewith. In practice, the set of jaws 10 is also employed for grabbing a sheet pile lying horizontally at a construction site or on a delivery truck, and lifting and positioning the sheet pile to a vertical orientation prior to pile driving. For this purpose, the vibratory hammer 12 with the set of jaws 10 mounted thereon can be pivoted to a horizontal position from the vertical position illustrated in Figure 1 for picking up the sheet pile 32 using the excavator arm (not shown) for manoeuvring into position. With the set of jaws 10 in the open position as illustrated in Figure 5, the two moveable jaws 22b 4 1 WO 00/61878 PCT/AU00/00316 -6and 24b together effectively form a tray in which the sheet pile 32 can be received by a sliding movement prior to gripping. The guide flanges 44 help to guide this sliding movement of the sheet pile between the jaws and thereby ensure correct positioning of the sheet pile prior to closing of the jaws by activating the hydraulic rams 42.

The predetermined distance between the first and second pairs of jaws 22, 24 may be adjusted in order to accommodate different shapes and sizes of sheet metal pile. Also, it will be appreciated that by removing the guide flanges 44, the set of jaws 10 can be employed for lifting and driving a flat planar sheet pile (of non-folded form).

It will be apparent that the described embodiment of the set of jaws for sheet pile has a number of advantageous features, including the following: it allows the sheet pile to be more fully supported across its width thereby minimising flexing and distortion of unsupported surfaces during pile driving; it allows a more uniform distribution of the pile driving force transmitted from the vibratory hammer to the sheet pile; it can be readily modified and/or adjusted to accommodate a variety of shapes and sizes of sheet pile; and, it can be readily mounted on and is fully compatible with, conventional vibratory hammers.

Numerous variations and modifications may suggest themselves to persons skilled in the pile driving arts, in addition to those already described, without departing from the basic inventive concepts. For example, a third pair of jaws could be provided between the first and second pairs of jaws for gripping the central coplanar surface 36 of the sheet metal pile 32. All such variations and modifications are to be considered within the scope of the present invention, the nature of which is to be determined from the foregoing description and the appended claims.

Claims (7)

1. A set of jaws for a vibratory hammer for driving a sheet metal pile into the ground, said set of jaws including a first pair of opposing jaws and a second pair of opposing jaws, said first pair of jaws being spaced a predetermined distance, in a direction transverse to the driving direction, from said second set of jaws and being substantially aligned in a common plane with said second set of jaws, each jaw of each said pair of jaws having a substantially planar contacting surface of elongate rectangular configuration for compressibly gripping said pile at a predetermined planar surface thereof, and wherein said first and second pairs of opposing jaws are mounted on a common mounting plate adapted to be removably fixed to a vibratory hammer, whereby, in use, said pile can be firmly gripped by said set of jaws at two horizontally spaced locations to transmit a driving force to the pile.

2. A set of jaws for a vibratory hammer as defined in claim 1, wherein each said pair of jaws comprises a first stationary jaw and a second moveable jaw

3. A set of jaws for a vibratory hammer as defined in claim 2, wherein said moveable jaw is provided with a guide flange along one edge thereof, said guide flange assisting with locating said sheet metal piling between said first and second pair ofjaws

4. A set of jaws for a vibratory hammer as defined in claim 3, wherein said guide flange extends at a predetermined angle to the contacting surface of said movable jaw, whereby, in use, when the jaws close the guide flange is not in force transmitting contact -with the sheet pile.

A set of jaws for a vibratory hammer as defined in claim 2, wherein each said movable jaw is driven by an hydraulic ram capable of producing a compressive force sufficient to firmly hold said pile during pile driving.

6. A set of jaws for a vibratory hammer as defined in claim 1, wherein said predetermined distance between said first and second pairs of jaws is adjustable, to AENO SHEV IWAU PCT/AU00/00316 Received 24 January 2001 accommodate different types of sheet metal pile. accommodate different types of sheet metal pile.

7. A set of jaws for a vibratory hammer as defined in claim 1, wherein said sheet metal pile is of folded form having a plurality of first and second coplanar flat surfaces and a plurality of first and second diagonal planar surfaces joined by fold lines, and wherein said first and second pairs of jaws are arranged to grip respective pairs of flat surfaces of one of said plurality of first and second coplanar flat surfaces. AEN=E SHEET OWJIAU