US1649160A - Bolt anchor - Google Patents

Description

Patented Nov. l5, 1927.

UNITED STATES Ltalu PATENT OFFlClE.

JOSEPH K. FISHER, OF SANTA MONICA, CALIFORNIA, ASSIGNOR TO TOEN EIWARZD OGDEN, OF MOUNTAINVILLE, NEW' YORK.

BOLT ANCHOR.

Application filed January 7, 1921.

My invention relates to improvements in bolt anchors or expansion shields, and has for its object the provision of a simplified and very effective device of this character.

In bolt anchors as heretofore made, it is customary to provide the body or walls of the anchor with external projections of one kind or another, which are forced against or into the surrounding material in which the anchor is placed as the latter is expanded, usually by a lag screw. It is found that in this form of anchor the main body portion or walls of the anchor are more or less spaced from the surrounding material, the degree of spacing depending among other things, upon the depth of penetration of the projections. In cases where the walls are in contact with the surrounding material, the closeness or pressure of Contact on the walls is not as great as would be the case if there were no external projections. It is also found that the external projections tend to cut grooves in the surrounding material if for any reason the anchor is accidently moved around or pulled out of the hole in which it is placed.

This grooving is objectionable for various reasons, among which the following may be mentioned: When the anchor is reinserted in its hole, the projections will enter the grooves already formed, thus making satisfactory holding engagement well nigh impossible, or if such engagement should be effected temporarily, there is the ever present possibility that it will be accidentally drawn out or rotated about its axis along the broken surface existing in the surrounding material. Furthermore, since the projections enter the surrounding mate-rial, the diameter of the hole is enlarged at those points with the result that eventually the hole would be too large for the anchor.

When soft metal sleeves with cylindrical outer surfaces are used, the smoothness of their outer surfaces is more or less liable to slip and thus fail to provide the firm holding engagement with the surrounding material which is needed.

It is the purpose of my invention to provide a bolt anchor which shall not be open to the objections mentioned and which at the same time shall enable thorough gripping action to be obtained and which can be manufactured at a minimum cost.

Briefly stated, the invention consists in providing the walls of the anchor with pits Serial No. 435,619.

or surface depressions instead of outwardly extending projections. These pits provide spaces into which the surrounding material may enter as the anchor is expanded into intimate contact therewith, the intruded material offering positive resistance to the with drawal or rotation of the anchor as long as the same is maintained in the expanded position. On the other hand, when the expanding means is removed, the anchor may be readily withdrawn without any injury to the surrounding material and may be replaced without any thought or care being given to the former positions occupied' by said depressions with respect to the surrounding material. My invention also makes possible the obtainment of intimate contact between the walls of the anchor and the surrounding material, thus materially increasing the frictional resistance obtained when `the anchor is expanded into place.

For a further understanding of the invention, reference is made to the detail description and drawings forming a part of this specification.

In the drawings:

Figure l is a view showing an anchor which embodies this invention having in its walls a series of pits in the form of perforations, portions being broken away to show the screw threads.

Figure 2 is a transverse section of the anchor shown in Figure l.

Figure 3 is a transverse section which shows the pits in the form of surface indentations or recesses.

Figure 4f is a transverse section which shows a shield provided with both the pits and the surface indentations of Figures 2 and 3.

Figure 5 shows the invention applied to an anchor of the machine bolt type.

Figure 6 is a transverse section through the anchor body shown in Figure 5.

In the drawings, like reference characters designate like parts throughout the several views.

In the form ofthe invention shown in Figure l, the anchor consists of a cylindrical body which is divided into at least two parts l0 and ll. The bore of the anchor may be of any desirable or suitable shape and may be provided with threads l2 for cooperation with the threads of a. lag screw. At regular or irregular intervals the exterior walls of the anchor are provided with pits or recesses 13 of appreciable depth, those in Figure 1 bein r shown as extending through the anchor waIls. In some instances, it may not be desirable to perforate the walls of the anchor and in such cases shallow pits 13 may be provided, as shown in Figure 3. If desired, the depressions may consist of both recesses and perforations, as shown in Figure 4.

The invention is not limited to the form of anchor shown in Figure 1. It may be embodied in anchors which are adapted to be expandedby any suitable means. As an example, I have shown in Figure 5, the invention embodied in an anchor of the type adapted to be expanded by a machine screw, a form well known in the art and comprising as usual separate parts 10 and 11 which together form at their ends inwardly tapered bores in which are fitted tapered expanding members 20, 21, one of which is a collar with a clearance hole for a bolt and the other of which is intcriorly threaded to form a nut.

wWhile I have illustrated the surface recesses or depressions as being of diamondshaped form, it is to be distinctly understood that the invention is notlimited to any particular form of pits or depressions. It is however, advantageous to have the edges of the pits or depressions with well defined marginal edges.

What I claim is:

An expansion shield formed of relatively thick cast metal and having its exterior expansible surface in the forni of a cylinder and surface depressions in said surface, said depressions being spaced circumferentially and longitudinally and the marginal edges of the depressions being well defined.

In witness whereof, I hereunto set my hand this 27 th day of December, 1920.

JOSEPH K. FISHER.

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