US3635292A

US3635292A - Pile grips

Info

Publication number: US3635292A
Application number: US55700A
Authority: US
Inventors: Anthony Edward Walter Last
Original assignee: BSP International Foundations Ltd
Current assignee: BSP International Foundations Ltd
Priority date: 1970-07-17
Filing date: 1970-07-17
Publication date: 1972-01-18
Anticipated expiration: 1989-01-18

Abstract

A fluid-operated pile driver incorporating a pair of jaw members to grip the pile to prevent the upward reaction force from lifting the housing of the driver during the downstroke of the ram, gripping of the pile being achieved through a piston attached to one of the jaw members, the piston and associated member being movable towards and away from the other jaw member by means of a diaphragm, subjected to the pressure of a fluid supply, cooperating with the piston.

Description

United States Last it tet [54] PILE GRIPS 21 Appl. No.: 55,700

[451 Jan. 18,1972

Primary Examiner-James A. Leppink Attorney-Jones and Lockwood [57] ABSTRACT [52] U S Cl 173/132 A fluid-operated pile driver incorporating a pair of jaw mem- [51] 7/00 hers to g p h p to prevent the upward reaction force o [58] Field of Search 173/159 166]20 lifting the housing of the driver during the downstroke of the 175/55 ram, gripping of the pile being achieved through a piston attached to one of the jaw members, the piston and associated member being movable towards and away from the other jaw [56] References Cited member by means of a diaphragm, subjected to the pressure of NlT AT PATENTS a fluid supply, cooperating with the piston.

3,433,311 3/1969 Le Belle ..175/55 9 Claims, 2 Drawing Figures l I 6 r-9 a 7 1 I l 7 a m I? 22 U 25 16).

5'! 92' 6 21 00 20 l t 24 L 2 b I 1' i i {/12 I iuio V32 f l p e I, -fl26 7 f 16 26 5'0 L 17 & Lari" FILE GRIPS This invention relates to pile-driving apparatus and to pile grips for use with such apparatus.

in the operation of pile drivers or hammers having a doubleacting mechanism, if the apparatus is not directly attached to the pile, the reaction force during the down stroke of the mechanism can lift the hammer from the pile in the absence of special precautions, so reducing the efficiency of the driving operation and. possibly leading in certain circumstances to misalignment between the hammer and the pile. It is known to avoid these difficulties by increasing the weight of the hammer but this has obvious disadvantages. Rubber friction grips have also been employed but these are inconvenient to use in practice.

The use of a gripping device operated by fluid pressure can offer certain advantages, particularly if the driver or hammer is itself operated by fluid pressure, when the gripping device can be actuated from the same power source, but there are difficulties in practice of providing for and maintaining the sealing of the gripping device, especially since the equipment can be expected to have to operate exposed to the difficult conditions of earthworking and construction sites.

According to the present invention, there is provided for use in a fluid-operated pile driver, a pile grip comprising a pair of jaw members to be disposed below an anvil of the driver, at least one of the members having a clamping piston mounted to it on guide means, a diaphragm subject to fluid pressure cooperating with the piston to displace said piston and associated jaw member on the guide means, in accordance with said fluid pressure, towards the other jaw member, bearing surfaces of said jaw members being arranged to cooperate with a pile to grip the pile and attach it to the driver.

Such a diaphragm-sealed arrangement is particularly suited to operation in dirty conditions where the life of 'a conventional piston seal would be expected to be considerably shortened.

The guide means may comprise a support ring in which the piston is movable, and a backing plate for said ring, the diaphragm being located in an annular recess between said ring and plate.

Preferably the diaphragm is a loose fit in said recess to be slidable over the inner surface of the support ring with displacement of the piston and bearing against the support ring to seal thereon when subjected to fluid pressure.

Conveniently, the grip comprises opposed leg members by means of which it is attached to a body or frame portion of the driver above the anvil and the anvil may be located at its peripheral regions by the leg members.

Preferably, the jaw members are arranged to be adjustably spaced from each other, independently of the relative displacement that can be provided by said piston.

One embodiment of the invention will be more particularly described with reference to the accompanying diagrammatic drawings of which:

FIG. 1 shows the lower region of a pneumatic pile driver or hammer with a pile grip according to the invention, and

FIG. 2 is a detail of FIG. 1.

Referring to the drawings, the pile driver comprises a casing or frame 2 mounted in which there is an operating mechanism (not shown) of any one of a variety of forms actuable by pneumatic pressure. One example of a suitable mechanism is illustrated in my copending application No. 698,624, issued as US. Pat. No. 3,529,511 on Sept. 2.2, 1970. At the bottom of the casing 2 there is secured anvil 4 on which is impacted a piston weight (not shown) forming part of the pneumatically operated mechanism, to drive a pile P on which the anvil bears.

To hold the pile driver securely to the pile during driving operations, a pile grip is provided comprising a pair of opposed leg members 6 bolted to the casing 2 to depend below the anvil 4, each carrying a jaw member 8 of the grip in that lower depending region and having a locating shoulder 7 that is received in a recess 9 of the anvil. Bottom faces 7a of the shoulders are not normally engaged bythe anvil in operation but provide a support for the anvil when the driver is suspended out of contact with the pile and prevent the anvil impacting the opposed faces of the jaw members should there by any fracture or uncontrolled movement of the pile. To form these faces, each jaw member comprises a gripping plate, l0,

12, respectively between which the pile P is located and the plate 10 is displaceable towards and away from the plate 12, it being secured to a piston 14 that isslidable in a support ring 16 including a nylon bearing ring 17 which prevents fretting between the piston 14 and the ring 16. Welded to the support ring 16 is a backplate 18, an annular recess 19 being formed between the support ring and the backplate as shown most clearly in FIG. 2. A diaphragm 20 extends over the backplate l8 and has its peripheral region fitting freely into this recess. An air supply line 22 is connected to a port 24 in the backplate so that, with the admission of pressure air, the diaphragm is displaced to urge the piston 14 and attached plate 10 outwards in the support ring 16, and the pile is thereby gripped between the two

plates

10, 12. The peripheral region of the diaphragm 20, being a loose fit in the recess, slides with the displacement of the diaphragm and is urged by the air pressure into sealing engagement against the shoulder of the support ring 16. Since the peripheral region of the diaphragm can thus move under the force of the air pressure, there is less tendency for high local stresses to be built up in it and a large stroking movement is possible without undue stretching of the diaphragm material at any point. At all times, of course, the complete peripheral edge of the diaphragm will remain in the recess 19 so that a seal can be maintained.

In the illustrated embodiment, the piston 14 is 10 inches in diameter and the depth of the annular recess I9 is seveneighths inch. The diaphragm 20 is of A inch thick neoprene of 60 Shore hardness although any suitable rubberlike material, which is flexible and oil resistant to combat the hammer lubricating oil suspended in the pressure air, could be used.

The maximum stroke of the illustrated piston is some fiveeighths inch, although a stroke of 1% to 2 inches could be achieved by suitable modification to the grip assembly. The two main limitations to be considered in any such modification are the increasing difficulty of assembly of the diaphragm into the deeper recess that would then be required and the increased wrinkling of the periphery of the distended diaphragm as the stroke increases.

Weld beads 24 are provided on the opposed faces of the

plates

10, 12 to improve their grip on the pile and the plate 10 has a flared lower portion 25 that assists location of the apparatus when it is initially lowered into position on the pile.

The jaw members 8 each comprise a pair of parallel plates 26 welded to the plates l2, 18 respectively, the assemblies being stiffened by gusset plates 28, and each pair of plates 26 embraces pads 30 that form a widened box section over a part of the length of the leg members 6. The jaw members are secured to the pads by bolts 32 passing through apertures 34, of which there are a plurality of sets so that the lateral spacing between the gripping faces can be adjusted to suit varying sizes of pile, independently of the pneumatic displacement of the gripping face 10 which is relatively limited in extent.

In operation, the grip steadies the hammer on the pile to maintain the hammer and pile in alignment with each other and has the particular effect when the driver employs a double-acting mechanism, of preventing separation between the pile and the driver that might otherwise be caused by the reac-.

tion forces developed in the driver casing during the downwards stroke of the piston weight. Since the grip can employ the same pressure fluid as the driving mechanism-in the drawing the supply line 22 is shown as a tapping from the main pressure supply line 36 leading to the driver mechanismit is relatively simple to apply and operate. In the case of a hydraulically operated hammer, the grip could of course be arranged to be operated by the same pressure liquid.

Whatl claim and desire to secure by Letters Patent is:

1. A fluid-operated impact-type pile driver for driving a pile, the driver having an anvil and including a pile grip comprising a pair of jaw members to be disposed below the anvil, bearing surfaces on said jaw members, a clamping piston mounted on at least one of the jaw members, guide means for the piston, a diaphragm cooperating with the piston, and a fluid supply acting on said diaphragm, the arrangement being such that the diaphragm displaces the piston and the associated jaw member on said guide means towards the other jaw member with the application of pressure by the fluid supply, the hearing surfaces of said jaw members thereby cooperating with the pile to grip the pile and attach it to the driver,

2. A pile driver according to claim 1 in which the guide means comprise a support ring in which the piston is movable, and a backing plate for said ring, the ring and plate defining an annular recess therebetween, the diaphragm having a peripheral region which is located in said recess.

3. A pile driver according to claim 2 in which said peripheral region of the diaphragm is slidable in the annular recess with displacement of the diaphragm and said peripheral region is arranged to seal against the support ring by the fluid pressure applied to distend the diaphragm.

4. A pile driver according to claim 1 and having a body portion, the pile grip comprising opposed leg members by means of which it is attached to the body portion above the anvil.

5. A pile driver according to claim 4 in which the anvil has a peripheral region and is located at said region by the leg members.

6. A pile driver according to claim 1 and having adjustment means for the jaw members which permit adjustment of the spacing between said members independently of the relative displacement provided by said piston.

7. A pile driver according to claim 1 in which plates, one attached to the piston and the other to the other jaw member, form the bearing surfaces of thejaw members.

8. A pile driver according to claim 7 in which at least one of the plates has a flared lower portion to assist initial location of the driver on the pile.

9. A fluid-operated pile driver for driving a pile, the driver having an anvil, opposed leg members depending from the anvil, respective mounting means on said opposed leg members, respective jaw members carried by said mounting means, one of said mounting means comprising piston guide means, a clamping piston displaceable on said guide means to move the jaw member of the associated leg member towards the other jaw member, a diaphragm mounted on said one mounting means to define a boundary of a closed space, a recess on said mounting means peripherally of said space, a peripheral region of the diaphragm slidable within said recess, and a fluid supply means connected to said closed space, the arrangement being such that application of fluid pressure from said supply means to said space distends the diaphragm to slide said peripheral region partially from said recess and said distension of the diaphragm displaces the piston on said guide means to move its jaw member towards the other jaw member, the jaw members thereby cooperating to grip the pile.

* IF =I UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Dated January 18, 1972 Patent No. 3', 635, 292

Inven or( Anthony Edward Walter Last It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Cover Sheet 32 Priority July 23, 1969 [33 Great Britain (SEAL) Attest:

EDWARD Y M.FLETCHER ,JR ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents USCOMM-DC 60370-P69 U.5. GOVIRNMEN'I' PRINTING OFFICE I", 0-366-3 4 'ORM PO-105O (10-69)

Claims

1. A fluid-operated impact-type pile driver for driving a pile, the driver having an anvil and including a pile grip comprising a pair of jaw members to be disposed below the anvil, bearing surfaces on said jaw members, a clamping piston mounted on at least one of the jaw members, guide means for the piston, a diaphragm cooperating with the piston, and a fluid supply acting on said diaphragm, the arrangement being such that the diaphragm displaces the piston and the associated jaw member on said guide means towards the other jaw member with the application of pressure by the fluid supply, the bearing surfaces of said jaw members thereby cooperating with the pile to grip the pile and attach it to the driver.

7. A pile driver according to claim 1 in which plates, one attached to the piston and the other to the other jaw member, form the bearing surfaces of the jaw members.