US2086213A - Post driver - Google Patents

Description

y 1937- e. L. COLLORD 7 2,086,213

POST DRIVER Filed,Nov 14, 1934 ff yu INVENTOR afolu g'w md lma ATTORNEYS Patented July 6, 1937 UNITED STATES PATENT OFFICE 1 Claim.

This invention relates to a composite metallic post, of the general nature of the post disclosed in my co-pending application Serial No. 737,716, filed July 31, 1934, and to the combination of 5 such post with a driving hammer peculiarly adapted to the driving of the post.

Referring generally to my invention to which reference is above made, the post is a metallic post having both strength and resistance to corrosion.

In accordance with the disclosure of my above application, I make posts, for use in fencing, and as highway guard posts, as composite structures comprising a bar or rail of steel and a shoe of iron cast around the lower region of the steel bar or rail. I prefer to use blast-furnace iron taken directly from the blast furnace, rather than cupola iron, for my shoe casting. This is for the reason that direct blast furnace metal contains a high percentage of carbon, and a maximum percentage of carbon in graphitic state. It has, therefore, fora ferrous metal, maximum resistance to corrosion; but is a highly fragile metal.

It is far more desirable to drive a post than to install it in a prepared post hole; for the reason that, as driven, the ground around the post is compacted, whereas in the case of a prepared post hole it is loosened. In order, however, that my post may accurately be driven to stand in true vertical position, and in order that angularly directed shocks and stresses be avoided in the shoe during driving, I so construct and arrange my post and a hammer in assembly with it that driving blows are delivered directly upon the upper extremity of the shoe, and are so distributed with respect to the shoe, that the shock ofthe hammer blow is directly along the longitudinal axis of the shoe.

In the accompanying drawing, elevation of my composite post. 7

Fig. II is a cross-sectional view, taken on the plane II II of Fig. I, through the cast metal shoe of the post and the steel bar of the post embedded in the cast metal shoe of the post; and

Fig. 11a is a similar view taken on the plane of Fig. II, but showing a modification in the contour of the cast metal shoe. I

Fig. III is a central vertical section through a. hammer adapted particularly to use in driving my composite post.

Fig. IV is an elevational view showing the assembly of my post and the hammer adapted for driving the post.

As explained in my co-pending application to Fig. I is a side.

which reference has been made above; it is my object to provide a post for driving which has a lower portion to be driven into the ground possessing great resistance to corrosion. As there explained, simple cast-iron which contains carbon in the graphitic state is a metal which resists corrosion to an unusual degree, and is one of the least expensive metals. It is, however, impractical to make wholly of cast-iron a post which extends a considerable distance above the ground level, into the region in which the post is subject to relatively severe'shocks and blows. This is for the reason thatcast-iron, being of low tensile strength, is readily fractured.

Referring to Figs. I and II ofthe drawing, it will be seen that my composite but integral post comprises an upper or bar portion l, which is shown as a bar of T-se-ction. It is to be understood that this bar I is of steelhaving a relatively high tensile strength. It is not necessary, however, that it be a special steel of any of the more expensive grades, since I have found that a relatively light post of common structural steel has an adequatelyhigh tensile strength to withstand severe impacts without breakage. The lower region of the post is in the form of an elongate, tapering shoe member 2, comprising, as shown in Fig. II, webs 2a and 21) forming a right angle with each other. In Fig. IIa. the webs 2a and 2c are shown as intersecting at right angles to each other. This shoe is cast around the lower region 3 of the bar I, and,,in casting, the bar and shoe may be anchored to each other in any suitable manner, as by making in this region of the bar perforations 3a.

In mounting the post it may, in accordance with mypresent invention, be driven into sub' stantially any sort of ground, save solid rock.

When used asa highway guard-post, it is usually 7 driven into-ground which is broken to make a; I fill, at the sideof the highway, and I have found that I may drive my post readily into such ground, and mayv even' drive it into undisturbed sub-strata of clay or shale. It is desirable that the shoe 2 be cf relatively great length, in order that the post may be buried to a depth below the frost line in the'soil, while leaving some small 7 proportion of the'shoe extending above'the surfaceo'f the ground; and in order that the shoe may have a relatively long engagement in the ground,,to resist removal of the post, or deflection of the post from a true vertical position.

While the requisite quality of the upper region,

or bar, of the post is tensile strength, therequisite quality in the shoe which lies below and at the surface of the ground is resistance to corrosion. For this reason I utilize cast-iron as the metal composing the shoe cast around the lower extremity of the post bar. Cast-iron, as noted, is the least expensive metal which could be used, and it may be easily and inexpensively cast.

While the common run of foundry iron may be used in casting the shoes of my integral posts, since it comprises a relatively high-perecentage of carbon, I prefer to use molten metal taken directly from the blast furnace. One advantage of using blast furnace metal rather than cupola metal is that thecost of melting is avoided by such practice. A more cogent reason is that blast furnace iron contains a higher percentage of carbon than the cupola iron. I have found that blast furnace iron contains on an average from 4 to 4 total carbon, and that it contains at least 3.5% of carbon in the graphitic state. Blast furnace iron is, therefore, more resistant to corrosion than cast cupola metal which contains about 3.25 to 3.5% total carbon, a lesser proportion of which is in the graphitic state. Since the quality desired of the cast-iron shoe is resistance to corrosion, the use of metal taken directly from the blast furnace, rather than remelted cupola metal, is in itself of substantial advantage.

It may be stated, more generally, that the iron cast about the lower region of the post bar, to form the shoe, should contain at least three per cent. carbon. It is highly desirable, in order to secure long continued resistance to corrosion under all conditions of use, that the metal of which the shoe is cast contain at least three per cent. carbon in the graphitic state. While it is possible to add carbon to cupola metal, the nature and distribution of carbon in the iron is most desirable when blast furnace iron is used directly.

It will be noted that the upper face 4 of the cast shoe 2 is, as shown in Figs. I and IV of the drawing, a plane surface lying at right angles to the longitudinal axis of the bar I. Further, the formation of the shoe 2 by means of webs arranged angularly to each other serves to center along the longitudinal axis of the shoe the force of a blow struck squarely upon this upper face 4 of the shoe.

The special hammer of my assembly is so formed as to strike a centered blow directly and squarely upon the upper face 4 of the shoe. The hammer comprises an elongate, tubular portion 5, which has a bore of such cross-sectional dimension as. to embrace closely the bar I of the post. At the lower extremity of the tube 5, constituting the guide portion of my hammer, there is mounted a weight, which is arranged to extend concentrically about the tubular guide.

As shown in Fig. III of the drawing, this weight comprises a casing 6 and a weighting filler 7, engaged between the casing 6 and the wall of tubular guide portion 5. The weighting material I is desirably lead, or other extremely heavy material, and the casing 6 is desirably welded to the tubular portion 5 to hold the heavy filler I firmly in position at the lower extremity of the tubing. It should be noted that the floor 6a of the hammer, which floor is desirably formed as a part of casing 6, presents a plane annular striking face, normal to theaxis of the tubular guide portion 5 of the hammer. Desirably, the tubular guide portion 5 of the hammer is provided with diametrically extending handles 8, Welded or otherwise suitably secured to this portion of the hammer.

In the operation of driving my composite post, the pointed, lower terminal 9 of shoe 2 is positioned at the point on the surface of the ground where the post is to be driven, and the post is brought to a true vertical position. The assembly of post and hammer having been made. the hammer is raised a suitable distance, and is allowed to fall, so that the plane, lower face 6a of the hammer strikes the plane, upper face 4 of the shoe a direct and squarely delivered blow. Desirably, as is usual, a few relatively light spudding blows are first struck, and thereafter greater driving force is obtained by raising the hammer along the bar I a greater distance above the upper face of the shoe.

During the driving of the post, the centering of the hammer by elongate tubular guide portion 5, which embraces the bar I, and the direct, square blows of the hammer weight delivered on the upper face of the shoe prevent deflection of the post as a whole from a direct, vertical position. Also the blow struck, being imposed directly at the lowest possible point, which is on the upper face of the shoe, and being delivered squarely and concentrically, there is no angular force produced by the blows of the hammer which might tend to crack or strain the fragile metal of the shoe. On the contrary, the shock of the blows is delivered axially of the shoe, and axially of that portion 3 of the bar I, which extends concentrically into the shoe and there serves as a reinforcement to the cast metal of the shoe. Thus fracturing tendency is effectively neutralized, during the operation of driving thepost, by the definite axial distribution of the driving shocks imposed by blows of the hammer.

I wish to emphasize the fact that, in my metallic post, high resistance to corrosion in the shoe is necessarily coupled with lack of toughness of the shoe metal. Directly cast, blast furnace iron, containing as it does a high percentage of graphitic carbon, is of particularly high fragility. It has been my observation that the fragile shoe of the post does not tend to fracture even when driven into resistant material, if the shoe be maintained accurately in perpendicular position, and if the driving blows be squarely delivered. If, however, the post is allowed to deviate from the vertical, or if stresses oblique to the longitudinal axis of the post are imposed on the shoe, cracking, or absolute breakage, of the shoe becomes far more probable.

It is a fact that the driving of my composite metal post is of great importance commercially, as well as in practice. The economy effected in eliminating the digging of post holes, coupled with the fact that the greater weight of the post is in a shoe of inexpensive cast-iron, permits my metallic posts to be used in competition with Wooden posts. An article of industrial production may thus be substitutedfor one obtained directly from natural resources.

It is to'be understoodthat the term bar as used throughout the specification and claim is not used in a technical sense. element is to be considered in the sense of the specification and claim to constitute a bar. Further, it is within the contemplation of my invention to utilize wrought-iron either in the form of a solid section, or in the form of a tube, to replace what is technically termed steel in the upper, or bar, portion of my composite metallic post. While wrought-iron has a greater resistance to corrosion than ordinary steel, its resistance to corrosionis relatively low, as compared Thus a tubular.

to cast-iron. While its tensile strength is not so great as that of ordinary steel, it is great as compared with cast-iron. Wrought-iron is, therefore, to be considered the substantial equivalent of steel in my composite metallic post.

I claim as my invention:

As an article of manufacture for use with a composite metallic post comprising an elongate bar element for extension above ground and a ground-penetrating heavy shoe of fragile corrosion-resistant metal embedding the lower region of said bar element, said shoe being pointed for driving and having an upwardly presented surface radiating in common plane from the bar element of the post; a driving hammer for striking axially distributed blows upon the upwardly presented face of such post comprising an elongate tubular element adapted to embrace the bar element of such post and having projected therefrom means for lifting engagement of the hammer, and a weight element mounted and wholly concentrating the driving weight of the hammer at the lower terminal of the said tubular element, said weight element being in concentric relation to the said tubular element and presenting for striking contact with the upwardly presented face of the post shoe a striking face extended radially beyond the tubular element and of an area adequate simultaneously to contact a relatively great area of the upwardly presented face of a post shoe extended in common plane from the axis of the post bar and the tubular element of the hammer; whereby in use of the hammer the blows thereof are delivered directly upon the upper face of the post shoe and are uniformly distributed thereover thereby protecting the post against the shattering effect of blows delivered angularly or upon a, surface spaced vertically from the upwardly presented face of the post shoe.

GEORGE L. COLLORD.

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