US3039546A

US3039546A - Free-fall drive-hammer assembly

Info

Publication number: US3039546A
Application number: US772232A
Authority: US
Inventors: Leroy W Janson; Stanford B Jones
Original assignee: Sprague and Henwood Inc
Current assignee: Sprague and Henwood Inc
Priority date: 1958-11-06
Filing date: 1958-11-06
Publication date: 1962-06-19
Anticipated expiration: 1979-06-19

Description

June 19, 1962 L. w. JANSON ETAL 3,039,546

FREE-FALL DRIVE-HAMMER ASSEMBLY Filed Nov. 6, 1958 3 Sheets-Sheet l FIG. FIG. 2

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INVENTORS Z'ROY W. J'fl/VSON STANFORD B. JONES J F ATTORNEY June 19, 1962 Filed NOV. 6, 1958 L. W. JANSON ETAL FREE-FALL DRIVE-HAMMER ASSEMBLY l8 '7 "r (0 V w v 48 4 A K Sheets-Sheet 2 x, x a

1N VENTORS United States atent D 3,039,546 FREE-FALL DRIVE-HAMMER ASSEMBLY Leroy W. Jansen, Clarks Summit, and Stanford B. Jones,

North Abington Township, Lackawanna County, Pa.,

assignors to Sprague & Henwood, Incorporated, Scranton, Pa., a corporation of Pennsylvania Filed Nov. 6, 1958, Ser. No. 772,232 3 Claims. (Cl. 175-152) This invention is directed to a drive-hammer assembly for soil-testing equipment and has for one of its objects to provide an assembly which is free-fall and fully automatic in operation.

For purposes of soil-testing it is necessary to measure the penetration resistance of the soil, which is done generally by dropping an iron block of a known weight a measured distance upon the soil sampler and counting the number of blows required to advance the sampler one foot, or other predetermined distance, into the soil. With this information, charts are referred to so that an indication of the bearing capacity etc. of the soil is obtained.

The most common method now employed is to use a cast iron or cast steel drive block, which is raised and lowered by means of a manila rope over a cathead or cargo-type winch. This procedure is crude, inaccurate, and on the whole not very satisfactory.

An object of the present invention is to provide a drivehammer assembly in which the hammer is hydraulically raised a measured distance, then released and allowed to fall freely against the drive head, which transmits the driving force of the hammer to the Sampling device. This cycle is repeated automatically as many times as necessary to advance the sampling device a prescribed distance.

The assembly is not only hydraulically operated but is fully automatic in that, while the hammer is raised hydraulically and then released for a free fall, this cycle being repeated as many times as desired, it is unnecessary manually to control a valve or the like for reversing the hammer movements.

In the accompanying drawings, in which an embodiment of the invention has been illustrated,

FIG. 1 is an elevational view of the assembly; and

FIGS. 2, 3, 4, and are sectional, elevational views taken along the lines 2--2, 3-3, 44, and 5-5 of FIG. 1, respectively.

Referring to the drawings in detail,

2 designates the drive head of the drive-hammer assembly, which, it is to be understood, will be threaded or otherwise rigidly coupled to a drill casing or drill rod, which in turn is attached to the sampler to be driven.

Threaded into the top of the drive head 2 is a fixed cylinder 4, the outer end of this cylinder being provided with cylinder head 6.

8 designates the drive hammer which is to be dropped upon the drive head 2, as will be explained later, this drive hammer being slidable along the cylinde 4. 10 designates a lifting ring carried by the drive hammer. Mounted within the cylinder 4 for reciprocation therein is a piston 12. Extending through the piston 12, axially thereof from the inner or lower end of the piston to the outer or upper end of the assembly, is a tubular member 18, to be referred to hereinafter as an outlet-valve extension member or valve stem. The inner or lower end of this member is enlarged to provide an inner valve spool 20, and threaded upon this spool 26 is an outer valve spool 22. The outer valve spool 22 overlaps the outlet valve stem 18 for a substantial distance and is spaced from the valve stem as shown in FIG. 4, so as to provide for the reception of the inner end of the hollow shank 24 of the piston 12. The valve stem or extension member 18, the two valve spool-s,

Patented June 19, 1962 and piston 12 have relative sliding movement within the cylinder 4.

The inner and

outer valve spools

20 and 22 are provided with

cooperating ports

26 and 28, respectively, while the outer valve spool 22 and piston shank 24 are provided with

cooperating ports

30 and 32, respectively.

The piston rod 34 for the piston 12 is tubular and carries a pressure inlet T 36, which is threaded thereto, as seen in FIG, 2. Packing gland 38 for the outlet valve stem 18 is threaded into the pressure inlet T 36.

Fixed to the piston rod 34 below the pressure inlet T 36 is a lifting tube 40, rigidly secured to the piston rod 34 by retaining ring 42, so as to be reciprocated with the rod.

Mounted on the exterior of the lifting tube 40 is a plurality of lifting hooks 44. Each hook is pivoted intermediate its ends to the lifting tube, as shown at 46, and the hooked end of each hook is urged inwardly toward the cylinder 4 by a spring 48.

Trip earns 59 for the lifting hooks 44 are secured to the outer surface of the cylinder 4, as seen in FIG. 3.

As shown in FIG. 4, the outlet-valve extension member or valve stem 18 carries a plurality of spool-actuating lugs 54, which project outwardly radially with respect to the extension member 18 through slots 56 in the wall of the piston rod 34. It is to be noted that the slots are substanti-ally larger than the lugs so as to permit of relative axial movement between the piston rod 34 and valve extension member 18.

Assuming that the pressure inlet T 36 is connected to a source of oil or other fluid under pressure and that the tubular outlet-valve extension member or valve stem 18 is connected to a suitable tank or the like and that the drive head 2 has been connected to the drill casing or drill rod, which, of course, is attached to the soil sampler; also assuming that the drive hammer 8 is resting upon the drive head while the lifting tube 40 is in raised position, as shown in FIG. 1; if pressure fluid is then admitted to the pressure inlet T 36, the fluid will flow. downwardly through piston rod 34 between the rod and the valve stem 18 and thence out through the slots 56 in the piston rod to the annular space between the piston rod and the cylinder 4. This applies pressure to the top of the piston assembly, so that the piston assembly, including the piston 12, piston rod 34, valve spools 2d and 22, the valve extension member or valve stem 18, as well as the lifting tube 40, etc., move as a unit downwardly or inwardly of the cylinder 4, fluid below the assembly exhausting through

ports

28 and 26 and valve stem 18 to a tank. When the outer valve spool 22 bottoms in the cylinder 4, further inward movement of the

spools

20 and 22 and of the valve stem 18 is arrested. Inward movement of the piston can continue, however, so as to close the

ports

26 and 28 and open the ports 3% and 32. The spool-actuating lugs 54 will now be at the top of the slots 56 in the piston rod 34 as distinguished from the position illustrated in FIG. 4, and pressure fluid is now free to flow between valve stem 18 and the shank 24 of the piston and through ports 32 and 30' to beneath the piston assembly to raise the same. As the piston assembly was descending, the lifting tube 40 and lifting hooks 4 were moved downwardly, so that the lifting hooks engaged the lifting ring 1i consequently, as the piston assembly is driven upwardly, the drive hammer 8 will be raised.

It should be noted that, when the piston assembly is in its innermost position, pressure will be applied both above and below the piston assembly, but, inasmuch as the area below the assembly is greater than that above it, the assembly and the drive hammer will be raised.

As the lifting tube 40 nears the end of its outer or upper stroke, the lifting hooks 44 will engage the disengaging cams 50, spreading the lifting hooks so as to release the drive hammer 8 to allow the same to fall freely upon the drive head 2. It will be appreciated, of course, that the time of release of the lifting hooks can be varied merely by shifting the piston of the earns 51 along the cylinder 4, to which they are secured by set screws 52.

Rising of the piston assembly continues for a short dis tance after the drive hammer 8 has been released until the spool-actuating lugs 54 engage the cylinder head 6. The piston, however, continues its upward movement for a short distance thereafter, so that the lugs will be shifted again to their initial position in the bottom of the slots 56, as shown in FIG. 4, the ports as and 32 will again be closed while the ports as and 28 will again be opened, so that another cycle of operation will begin. This cycle of operation will be repeated over and over again until the pressure entering at the pressure inlet T 36 is shut olf by the operator.

it will be seen from all of the foregoing that the present invention provides a drive-hammer assembly which is completely automatic in operation, the drive hammer being raised, released, and dropped time after time without manual assistance or control of any kind and, as above stated, will continue to operate in this fashion until pressure is shut off by the operator at the pressure inlet. inasmuch as the drive hammer is released by the action of the earns 50, Wnich are fixed in position throughout a run, it is a simple matter to raise the hammer a measured distance, release it after it has reached that distance, and allow it freely to fall against the drive head. The fact that the assembly is hydraulically operated is obviously of advantage over the rather crude method presently employed and is of considerable advantage for the further reason that many of the modern machines employed in core-drilling and soil-sampling operations are equipped with a hydraulic system, so that the drive-hammer assembly of this invention may readily be connected in the same hydraulic system.

It is to be unde" tood that changes may be made in the details of construction and arrangement of parts herein above described without departing from the spirit and scope of the invention.

What is claimed is:

1. A free-fall drive-hammer assembly comprising, in combination, a drive head; a free-fall hammer for driving said head; a fixed cylinder extendin through said hammer; a piston assembly within said cylinder, said piston assembly comprising a tubular piston, a piston rod, a valve stem within the piston and piston rod, slide valve mechanism at the inner end of said valve stem, and a lifting tube atte red to said piston rod; means for admitting fluid pressure to the drive-hammer assembly to drive the piston assembly, slide valve assembly, and lifting tube inwardly relative to said cylinder to effect coupling of the lifting tube to the said drive hammer, said slide valve being shifted automatically as the piston assembly nears the end of its inward movement to admit pressure fluid beneath the piston to move the piston assembly, valve stem, lifting tube, and hammer outwardly relative to said cylinder; and means operating automatically near the end of said outward movement of the piston assembly and lifting tube for uncoupling the drive hammer from the lifting tube to permit a free fall of the hammer upon the drive head, continued outward movement of the piston assembly effecting shifting of the slide valve mechanism into position to begin the next cycle of operation. 2. A free-fall drive-hammer assembly comprising, in combination, a drive head; a free-fall hammer for driving the same; a fixed cylinder extending through said hammer; a piston assembly within said cylinder comprising a tubular piston, a piston rod, a valve stem Within the piston and piston rod, carrying slide valve mechanism at its inner end, and a lifting tube attached to said piston rod; means for admitting pressure fluid to the drive-hammer assembly to drive the piston assembly, slide valve assembly, and lifting tube inwardly relative to said cylinder to efiect coupling of the lifting tube to said drive hammer, said slide valve mechanism shifting positively near the end of the inward movement of the piston assembly to reverse the movement of the piston assembly and lifting tube; stationary means engaged by the lifting tube on its outward movement to uncouple the hammer from the tube to effect a free fall of the hammer upon the drive head; and means operable on continued outward movement of the piston assembly to restore the slide valve mechanism to initial position, to cause the drivehammer assembly to begin another cycle of operation.

3. A free-fall drive-hammer assembly comprising, in combination, a drive head; a free-fall hammer for driving said head; a cylinder rigidly attached to said head; a tubular piston and a piston rod within said cylinder, the outside diameter of the piston rod being substantially less than the inside diameter of the cylinder; a shank for said piston; a tubular slide valve assembly within said piston shank, said valve assembly comprising an inner valve spool and a tubular valve stem rigid with said spool and extending along the interior of said piston shank in spaced relation thereto; a lifting tube rigidly attached to said valve stem; valve-operating lugs rigidly attached to said valve stem and extending radially therefrom through port slots in the wall of the said piston shank;

a head for said cylinder; means for admitting fluid pressure to the drive-hammer assembly, said fluid, with the said hammer resting upon the drive head and all other parts in outward position relative to said cylinder, imposing pressure upon the end of said piston to drive the piston assembly and associated parts inwardly of the said cylinder, the slide valve mechanism being positively shifted on this inward stroke of the piston and said lifting tube automatically coupling itself to the hammer, said shifting of the slide valve mechanism effecting reversal of movement of the piston assembly and associated parts to raise the hammer; means in the path of the outwardly moving lifting tube for automatically uncoupling the tube from the hammer near the end of the outward movement of the tube; and means carried by the valve stem thereafter engageable with said cylinder head to shift the slide valve mechanism to start another cycle of operation.

References Cited in the file of this patent UNITED STATES PATENTS 248,702 Button Oct. 25, 1881 2,804,857 Haage Sept. 3, 1957 FOREIGN PATENTS 138 Great Britain Jan. 2, 1909 29,031 Denmark Dec. 19, 1921 676,882 France Nov. 29, 1929