US 1980093 A
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Patented Nov. 6, 1934 1,980,093 ANCHORAGE DEVICE Heyman Rosenberg, New York, N. Y.
Original application January 16, 1925, Serial No. 2,874. Divided and this application May 13,
1925, Serial No. 30,008
This invention relates to improvements in the art of anchorage and in anchorage devices of the type especially adapted for use in metal and other hard substances and materials susceptible of be- 5 ing flowed while cold. This application is a division of my parent application Serial No. 2,874, led January 16, 1925.
An object in view is the causing of the flow of the material of work by successive steps into ay l compact, high-frictional relation to the engaging parts of an anchorage device for insuring rm anchorage incident to the application of relatively small stresses.
A further object in view is the effecting of an l anchorage with a minimum amount of stress and `with maximum eiiiciency.
With these and further objects in view as will in part hereinafter become apparent and in part be stated, the invention comprises certain novel steps and combination of steps in the art of anchorage, and also comprises certain novel constructions combinations and arrangements of parts as subsequently specified and claimed.
In the accompanying drawing,-
Figure 1 is, a view in side elevation of an anchorage device especially Well adapted for the practicing of the improved art, and embodying the features of the structural part of the present invention, the structure being shown in engagement with work, and the work being seen in vertical section, the parts being shown on a magniiied scale beyond that of the average commercial device. Figure 2 is a horizontal section taken on the plane indicated by lines 2-2 of Figure l, and
looking along the screw toward the head.
Figure 3 is a view similar to Figure 1 of the parts with the anchorage device only partway through the work, the upper portion of the anchorage device being omitted.
Figure 4 is a sectional view through the work after the anchorage device has been fully seated and subsequently removed.
Figure 5 is a. view similar to Figure 1 dfn slightly modied embodiment, the work being omitted and fragments of the anchorage device being broken away. y
Referring to the drawing by numerals, 1 indicates the body of an anchorage device which is preferably cylindrical and provided at its entering end with a smooth or pilot portion 2 of greater diameter than the diameter of the main portion of the body, the body terminating in a point or entering. cone 3. At the opposite end, the body 1 is preferably provided with an appropriate head 4, such as that of the ordinary screw, having the kerf 5 for receiving a rotating instrument. The body 1 is provided with a ribl made up of a section 6 and a section 7, each of said sections being preferably of a length approximately equal to the thickness or depth of the work 8, or at least equal to the distance throughout which the anchorage device is to engage the work when in its seated position. The 'rib making up the sections 6 and 7 in the embodiment shown in Figure 1 is arranged on a thread spiral corresponding with that of an ordinary wood screw thread and extends from the pilot 2 to the head 4. The rib is hardened in the sense in which the term hardened is employed in the metallurgical art to distinguish from soft metals, which is to say that the thread or rib making up the sections 6 and 7 is hardened suilciently for entering metal, such as soft iron or soft steel, substantially without injury to the thread. The method of hardening the thread or rib making up the sections 6 and 'l is susceptible of a wide range of variation, but for ordinary commercial purposes the hardened condition is preferably attained by subjecting the whole anchorage device to a case-hardening process, such as the well known cyanide process. The hardening of the other parts `of the 'structure beside the thread is an incident to such process, and While adding little, if any, value to the completed structure in no sense detracts therefrom and aiords an inexpensive means of producing a hardened thread.
As will be clear from the dotted showing at the intermediate portion of the anchorage device, as seen in Figure 1, the sections 6 and 7 are alined, and, in fact, continuous of each other, the thread or rib of section 6 tapering into the thread or rib of section 7, it being apparent from Figure 1 that the thread or rib of section 'l outstands from the body 1 a less distance than the thread or rib making up section 6. In other words, the rib for section 'l is smaller and of less dimensions in every direction except length and spacing between helices than is the thread or rib making up section 6. ,The thread or rib making `up sections 6 and 7 is a continuous spiral of uniform and substantially low pitch. The dimensions of therib or thread making up section '7 are the same, that is, uniform, throughout the length of the section, and similarly the thread or rib making up section 6 has its dimensions the same, that is, uniform, throughout the length of the section, and variation in dimensions occurs only at the point of junction of the '110 only sufliciently larger to allow passage of the4 pilot therethrough with a snug t. lli'he anchorage device is applied by the introduction of the point 3 into the opening 9, the taper of the point facilitating and assisting in centering the anchorage device and bringing the pilot 2 intoaxial alinement with the opening 9. The pilot is then passed into the opening with a longitudi- :nal thrust of the anchorage device until the entering end of the rib or thread of section 'lI engages the upper part of the work 8. The anchorage device is then revolved while preferably subjected to stress in the direction of its length toward the work 8, as, for instance, by having `the kerf 5 engaged by a screw-driver and the anchorage device revolved thereby. Thethread of section '7 begins to enter the metal of work 8, severing the same and forming a passageway therein similar to internal threads, and the revolving operation continues until the pilot 2 has passed through the work 8. course, that as soon as the thread has sufficiently entered the work, the longitudinal stress may be no longer required. It will be observed from the showing in Figures 1 and 3 that during the Asteps of the operation thus far described, the ithread or rib making up section 7 will have caused the metal of work 8 to flow to a position overhanging the annular shoulder at the upper end of the pilot 2 resulting from the fact that the pilot 2 is larger in diameter than that of the body 1. The owing of the metal of work 8 thus effected causes it to enter the valleys bee tween the helices of the rib and to frictionally engage the faces of the rib. Nevertheless, since .the rib or thread making up 'section 7 is of rela- ,tively shallow depth, the twisting stress neces sary for forcing the anchorage device into the .Work 8 is comparatively small.
When the anchorage device has reached the position with the pilot 2 extending beyond the work 8, the thread or rib will have reached that point at the upper surface of the work 8 where it tapers from the enlarged rib of section 6. However, as the internal thread produced by section '7 is completed before section 6 begins to enter, continued rotation of the anchorage device will cause section 6 to enter the Work with very little, if any, additional force or torsional stress required than that required for the introduction of section 7. Continued revolution of the anchorage device causes the thread or rib of section 6 to enter the material 8 and to proportionally increase the internal threads being formed therein until they assume the proportions indicated in Figure 4, the metal entered by the larger rib or thread being caused to ilow thereby to a greater extent toward the body 1 than was effected by the action of the smaller section of thread or rib until the material of the work.8 extends in toward the body 1, as indicated at 10, 10, in Figure 4, a distance occupying substantially all of the space represented by the It is obvious, of,`
difference in diameter of the opening 9 and the body 1, whereby the material of work 8 is caused to practically ll the valleys between the helices of section 6 and to proportionally increase frictional resistance to removal of the anchorage device. The anchorage device can, of course, after reaching the final seated position with the section 6 extending throughout the thickness of the work 8 be backed olf by a reverse or withdrawing rotation, but such rotation will be highly resisted by the friction effected by the flowed metal at 10, 10.
It will thus be seen that -in a very simple manner the anchorage is caused to assume a relation to the work without the exercise of any great amount of stress which it will maintain under all ordinary operating conditions.
In Figure 5 is illustrated a very slight modified l embodiment in which the body 21 is provided with a low-pitched thread or rib forming sections 26 and 27,.the rib for the section 26 being of greater dimensions than the rib for section 2'7 land tapering into the latter after the manner of the taper of the rib or thread making up section 6 into the rib or thread making up section 7. But, in the embodiment seen in Figureg, the body 21 is itself tapered at the place of tapering of the thread, producing a reduced portion 22 which causes the thread of section 27 to have approximately the same relation to that part of the body which it engages as has the thread of section 26 to its part of body 21. Where ay pilot is employed, the pilot willbe of a diameter bearing that relation to the body 21, or larger diameter of the body of the anchorage device, which pilot 2 bears to body 1. The operation of the structure seen in Figure 5 is the same as that described with'respect to the structure seen in Figure 1, except that in instances where metal may be caused to ow by the rib or thread 27 far enough to underhang the larger portion of the body, such flowed material is compressed by the body on reaching and passing the point of such flowed material, and an increased frictional engagement is thus effected.
Because of the difficulty of accurately illus trating so small a structure as the average commercial anchorage device, a magnified scalehas been utilized throughout the drawings, and yet, for the purpose of enabling those skilled in the art to understand that the proportions have been as nearly as practically maintained in these mag nied showings, it may be stated that an acceptable embodiment will have an overall longitudinal measurement of one inch; a diameter for the pilot 2 of one hundred thirty-two thousandths of an inch; and the body 1 one hundred eighteen thousandths of an inch. A. circle capable'of contacting at diametrically opposite points with projected diametrically opposite points of the edge of a helix of rib or thread 7, that is, such a circle as seen in Figure 2 representing said helix, in a structure of the size just mentioned should measure in diameter one hundred forty-six thousandths of an inch, and a corresponding circle for a helix of rib or thread 6 should' have a diameter of one hundred seventy-four thousandths of an inch. In other words, an anchorage device having an overall length of one inch should have a pilot one hundred thirty-two thousandths of an inch in diameter, a body 1 one hundred eighteen thousandths of an inch in diameten' a thread or rib.'7 outstanding from the body at any one point a maximum of fourteen thousandthsof an inch, and a thread or rib 6.out-
standing from the body at one point a maximum of twenty-eight thousandths of an inch.
Obviously, a wide range of variation from these measurements is clearly within the spirit, intent and scope of the invention, but the foregoing will give definite data for indicating the preferable lrelative proportions, and it should be noted that while only two sections, 7 and 6, have been illustrated, a number of such sections successively tapering into each other may be utilized for increasing the diameter or diametrical space occupied by the final engaging rib or ribs without substantially increasing the difficulty or stress necessary for locating the anchorage device in its final position.
It should also be apparent that in the practicing of the art embodying the present invention the material of the work is severed in a spiral path and caused to flow in an encircling mass toward the body of the anchorage device, and then, While the anchorage device continues to move, the flow is interrupted; and subsequently the encircling mass is further flowed toward the bOdy.
body and a single continuous thread of constant pitch outstanding therefrom hardened suii'lciently for entering metal, such as soft iron or soft steel, substantially without injury to the thread, said thread comprising' alined and joined sections of geometrically similar cross-section, each section outstanding from the body a constant distance and being of substantially uniform cross section within its own limits throughout its length, the section adjacent the entering end of the body outstanding a less distance than the HEYMAN RosENBERG.