US3416374A - Sampling device - Google Patents

Description

Dec. 17, 1968 c. s. SMITH SAMPLING DEVICE 7 Filed April 24, 1967 INVENTOR COLEN 5. SMITH ATTORNEY United States Patent ABSTRACT OF THE DISCLOSURE A device for obtaining samples of materials consisting of an outer cylindrical housing, a cutter-retainer mechanism which is inserted into the outer housing to loosen and hold the sample during withdrawal of the device and a valve mechanism within the cutter-retainer to release the vacuum in the area behind the device as it is withdrawn.

This invention resulted from work done by the Bureau of Mines of the Department of the Interior, and the domestic title to the invention is in the Government.

Background of the invention Representative samples of unconsolidated or poorly consolidated bulk materials are required for a variety of testing purposes. Such samples are routinely needed for the determination of density, moisture, composition and other properties of the materials sampled. The bulk materials sampled range from dry unconsolidated powders, such as cement, to cohesive, partially consolidated, liquidsaturated materials such as hydraulically emplaced fill materials.

The simplest type of device used for obtaining such samples consists of an open tube which is forced into the material being sampled. A core of material is squeezed into the tube and is retained there when the tube is withdrawn by friction with the interior tube walls. The use of this type of sampler is limited to a small range of materials. In sampling very soft or cohesionless materials, means must be provided to prevent loss of samples when the sampling device is withdrawn. Various types of sample retainers have been used to keep the core within the barrel or tube of the sampler. Examples of such retainers are various types of core springs, core baskets, flap and cock valves.

As the sampler is withdrawn, a substantial decrease in the pressure on the underside of the sample will occur which will greatly increase the danger of losing the sam ple. A partial vacuum will generally be formed below the sampler unless special measures are taken to admit water or air to the space below the sampler. It has been suggested that the passage of fluid along the outside of the sampling tube be facilitated by placing small longitudinal ribs on the outside of the sampling tube. When the sampler is then rotated, an annular space is formed which allows fluid to enter the space below the sample. This approach has been only partially successful.

It has also been suggested that a more positive means of maintaining the pressure below the sample be employed such as supplying compressed air to the void space below the sample via conduits in the walls of the sampling tube. This approach has two disadvantages; it requires additional equipment and the air conduits have a tendency to plug when sampling viscous materials such as clays.

The widespread use of bulk material sampling devices and the lack of a simple, dependable and versatile sampler has led to the present invention. This device was developed primarily for obtaining representative in situ samples for the determination of density of hydraulically emplaced backfill materials used in underground mining operations. Prior to the development of this device, one

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method of securing samples and data was to wait until the fill materials had solidified and then (1) make an irregularly shaped hole in the backfill material, (2) collect and weigh the cuttings, (3) use a water inflatable balloon device for determining the in situ volume of the sample hole, and (4) calculate fill density.

When using the sampling device of this invention, it is not necessary to allow the fill material to solidify prior to sampling. Total in-place volume of the obtained sample is equal to the cross-sectional area of the outer casing multiplied by its depth of penetration into the sampled material. A determination of the Weight of the sampled material then allows density to be calculated.

Accordingly, it is an object of this invention to provide an improved materials sampling device.

It is a further object of this invention to provide an improved bulk materials sampler which provides positive means for retaining the sample within the sampler barrel and which provides positive, automatically operating means for allowing fluid to fill the void formed by removal of the sample.

Description of the invention The invention will be more clearly understood from the following description of a preferred embodiment wherein reference is made to the accompanying drawings.

FIGURE 1 represents a sectional view of the complete sampler. FIGURE 2 is a sectional view taken on the line 22 of FIGURE 1. Referring specifically to the drawings, the outer housing consists of an open cylindrical tube or casing 1 having cutting means 2 at its lower end. These cutting means may be formed by sharpening the tube to provide a uniform cutting surface or may comprise a hardened, replaceable bit. The tube is preferably constructed of a hardenable, corrosion-resistant metal. Handles 10 may be attached at the upper end of the housing to facilitate its removal from the sampled material. Inserted within the outer housing is a hollow inner member or shaft 3 which has a handle 4 attached at the upper end and has sample cutting and retaining means 5 fixed to the open lower end. The hollow inner shaft preferably is constructed of a thick-walled rigid metal tube of a length equal to the length'of the outer housing so as to permit complete removal of the core sample cut by the casing. The cutting and retaining means may comprise a single turn helix or may comprise multiple spiral pitched vanes so as to provide a cutting and lifting action when the inner shaft assembly is rotated relative to the outer casing. The diameter of the cutting means is such as to provide a non-binding fit Within the outer casing.

A valve stem 6 extends through the interior of the hollow inner shaft and is attached at its lower end to a tapered or conical center valve 7 which forms a seal with valve seat 8. A valve stop 9 is fixed to the outer end of the valve stem in such a position as to allow a limited sliding movement of the entire valve assembly within the inner shaft, thus permitting the center valve to open and provide fluid communication through the annulus between the valve stem and the inner shaft, through the valve and into the area below the sample.

FIGURE 2 illustrates a preferred embodiment of the cutting and retaining means 5. Multiple cutting and retaining vanes can be conveniently formed from a flat, washer-shaped disk or ring of'any appropriate material. Incomplete radial cuts divide the disk into sectors and each sector is then shaped so as to provide a spiral pitch or auger configuration to the complete assembly. Although the drawing illustrates the use of four vanes, it is obvious that either a greater or a lesser number of vanes can be conveniently and successfully used.

In sampling, the sharpened end of the outer casing is forced into the material to be sampled by any suitable means, until penetration is deemed sufficient to secure an adequate portion of sample or until friction between the core and the inner wall of the casing develops resistance to penetration. The inner shaft assembly is then inserted in the casing and rotated. Such rotation causes the spiral pitched vanes at the end of the inner shaft assembly to penetrate the sample portion so as to cut, lift and retain it within the annular area between the inner shaft and the casing. Sample size is conveniently limited to the volume of the annulus formed by the inner shaft and the outer casing.

The sample portions are taken in successive increments by lifting each increment from the outer casing with the inner shaft-valve assembly and allowing the casing to remain in the sampled material. The casing is only removed after the total sample has been recovered and depth of penetration measured.

During insertion of the inner shaft assembly, the tapered center valve will close upon contact with sampled material thus preventing the material from entering the hollow inner shaft. When the sample portion is being removed, the valve will open and permit air or other fluid to flow into the area under the sample portion and thus prevent formation of a vacuum below the sample portion. The depth to which the sampler penetrates is measured and the material removed is weighed. From the volume of material removed and the weight thereof, the in-place density is readily calculated.

It will be understood that a number of variations and adaptations of the disclosed invention are possible without departing from its spirit or scope.

What is claimed is:

1. A sampling device comprising a tubular open-ended outer member having one end sharpened to form a cutting surface and adapted for forceable insertion into a relatively resistant material, an inner tubular member axially and concentrically disposed within said outer memher, said inner member having cutting and retaining means comprising multiple pitched vanes fixed to one end of said inner member and valve means comprising a stern extending through the interior of said inner member, stopping means so fixed as to provide a limited longitudinal movement of said valve means relative to said inner member and closure means comprising a conical member attached to said stem, the base of said conical member being of larger diameter than said inner memher and adapted to contact and seal the end of said inner zmember upon insertion into said relatively resistant material.

References Cited UNITED STATES PATENTS 1,847,136 3/1932 Rauberstrauch 73-4252 2,361,067 10/1944 Shaw 73-425.2 2,753,717 7/1956 Obrcian 73-425.2 3,217,547 11/1965 Cordell et a1. 73-424 LOUIS R. PRINCE, Primary Examiner. D. E. CORR, Assistant Examiner.

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