US 3762733 A
Description (OCR text may contain errors)
United States Patent 1191 Lana 1 Oct. 2, 1973 1 1 NAIL SCREW DRIVING TOOL HEAD 22 Filed: Jan. 20, 1972 211 Appl.No.:2l9,382
Related US. Application Data  Continuation-in-part of Ser. No. 769,294, Oct. 21,
1968, Pat. N0. 3,654,832.
52 us. Cl. 279/103, 2791/] M, 279/23 51 Int. Cl ..B23b 31/10 581 Field of Search 279/9, 102, 103,
279/95, 1 M, 96, 23; 145/50 R, 50 D, 50 DA; 81/125, 52.3; 408/223 3,485,520 12/1969 Alexander .0 279/102 X FOREIGN PATENTS OR APPLICATIONS 319,308- 4/1920 Germany 279/103 Primary Examiner-Gil Weidenfeld AttorneySpensley, Horn and Lubtiz  ABSTRACT A nail screw fastening system comprising a novel nail screw together with a tool head for driving it, the nail screw being easily fabricable by rolling or stamping threads on the pointed end of stamped nail stock so that the thread ridges project radially outward beyond the nail shank, and by cutting V-shaped peripheral notches in the nail head to form flanges. The driving tool head is an elongate body adapted at one end for coupling to a source of rotary motion, its other end having an axial passageway of cross section complementary to the cross section of the nail screw head flange and terminating in an end wall.
2 Claims, 17 Drawing Figures NAIL SCREW DRIVING TOOL HEAD CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation in-part application for patent of my co-pending application Ser. No. 769,294 for Nail Screw Fastening System filed Oct. 21, 1968, now U.S. Pat. No. 3,654,832.
BACKGROUND OF THE INVENTION It is well known that the holding power of a wood screw is generally significantly greater than that of a nail of the same length. However, wood screws require much more time and effort to install than nails and also are more expensive. Efforts to provide a fastener combining the best attributies of both screws and nails have resulted in the developmnt of a so-called screw nail, which is a nail in whose surface shallow helical depressions are formed, so that as it is driven in place with blows from a hammer it turns like a screw. Although screw nails have somewhat more holding power than ordinary nails, their holding power is still much less than that of screws and they also possess the disadvantageous characteristic of nails (and of screws when driven without pre-drilling) of the tendency to split the wood into which it is driven. So even after development of the screw nail there still has existed a need for an in expensive fastener which has the holding power of a screw, which requires much less time and effort to install than a screw of screw nail and which doesnt have a tendency to cause splitting. The present invention is directed toward a fulfillment of this need by providing a novel fastener and tool head for driving it.
SUMMARY OF THE INVENTION The fastener can be appropriately termed a nail screw" since it is driven by rotation rather than by pounding with a hammer and is, by stamping stock and rolling or stamping threads, as inexpensively fabricable as an ordinary box nail. The nail screw generally comprises an elongate cylindrical body having a pointed tip at one end and a circumferentially. projecting head at the other end, the body being longitudinally threaded from its pointed tip throughout a portion of its total length, the head defining a plurality of radially outward extending flanges for receptive engagement with the head of the present invention driving tool. One of the important features of the nail screw is that the minor diameter of the threads is substantially equal to the diameter of the remaining unthreaded portion of the cylindrical body, whereby the threaded ridges project radially outward beyond the circumference of the remaining unthreaded body portion. This is in contrast to the ordinary screw having ,cut threads, whereby the minor thread diameter is less than the diameter of the unthreaded screw body portion and the thread ridges do not define the maximum diameter of the screw body. This feature is important since it obviates the tendency for splitting since the unthreaded shank portion does not cause undue stressing of the wood as the nail.
screw is driven. Actually, the natural resiliency of the wood fibers results in the fibers contracting to close down onto the unthreaded shank portion behind the threads, thereby providing the desired strong holding power.
Another important characteristic of the nail screw fastener is its flanged head, designed for quick and easy engagement with the head of the driving tool.
The present invention driving tool head, in its preferred embodiment, is designed for use in a hand held rotator device, typically pneumatically or electrically driven. The tool head is basically an elongate body adapted at one end for coupling to the rotator device and defining an axial passageway extending from its other end to an end wall for the interior passage termination. Such end wall may be a permanent magnet designed to hold the nail screw in place prior to driving. The cross section of the passageway is substantially identical to but slightly greater than the head flange cross section of the nail screw to accommodate insertion of the head end of the nail screw to a driving position, wherein the nail screw head may abut against the end wall of the passageway, or such passageway may be of descreasing cross sectional dimension so that the nail screw head may be press-fit into the passageway without abutting the end wall.
An additional feature of the present invention tool head is that the nail screw receiving end of the body may be provided with a reduced diameter tip portion shaped to form a countersink, an annular shoulder limiting the countersink depth and providing for automatic withdrawal of the nail screw from the tool head at the completion of the driving operation.
Yet a further feature of a preferred embodiment of the present invention driving tool head is one or more axially extending slots through the tool head body to the passageway to facilitate the extraction of wood chips and the like during the driving and countersink of a nail screw.
The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages thereof will be better understood from the following description considered in connection with the accompanying drawings which illustrate the present invention system and components by way of example.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a pictorial drawingindicating the fastening system apparatus in use;
FIG. 2 is a perspective view of the driving tool head used in the apparatus of FIG. 1;
FIG. 3 is a perspective view of the nail screw used in FIG. 1;
FIG. 4 is a partial elevation view of the nail screw of FIG. 3;
FIG. 5 is a cross sectional view taken along the line 55 of FIG. 2;
FIGS. 6 and 7 are opposing end views of the tool head of FIG. 2;
FIG. 8 is a partial elevation view illustrating the countersinking operation of a tool head tip;
FIG. 9 is an elevation view, partially cut away of another embodiment of the present invention tool head; FIG. 10 is an end view of the tool head of FIG. 9;
FIG. 11 is aperspective view showing another embodiment of the nail screw;
FIG. 12 is a perspective view showing an alternative embodiment of the present invention tool head;
FIG. 13 is a partial sectional view of an alternative embodiment of the present invention tool head taken along the line 13-13 of FIG. 12;
FIG. 14 is an end view of an alternative embodiemnt of the present invention tool head taken along the line 114 of FIG. 13;
FIG. is an elevation view, partially cut-away, of an alternative embodiment of the present invention tool head;
FIG. 16 is a cross sectional view of an alternative embodiment of the present invention tool head taken along the line 1616 of FIG. 15; and,
FIG. 17 is a perspective view of the detail disclosed by the cut-away view of FIG. 15.
DESCRIPTION OF THE PREFERRED EMBODIMENTS Turning first to FIG. 3 of the drawing, an embodiment of the nail screw is generally indicated by the reference numeral 20. The nail screw 20 is a unitary structure comprising an elongate cylindrical body 21 having a pointed tip 22 at one end and a circumferentially projecting head at the other end. The screw body 21 is longitudinally threaded from the pointed tip 22 for about one-fourth to one-third of the total body length. It has been found that near-maximum gripping power and proper driving is obtainable when the threads extend for only about one-fourth of the body length. On the other hand, a threading length appreciably in excess of about one-third of the total body length could interfere with proper driving of the nail screw and its positioning in the head of the driving tool.
An important feature of the nail screw is that the threaded ridges project radially outward beyond the circumference of the unthreaded portion of the nail screw body. This feature is clearly shown in FIG. 4, the thread ridges 24 being of a greater diameter than that of the remaining unthreaded portion 23 of the nail screw body 21. The nail screw 20 can be easily and conveniently fabricated by stamping on the stock. with the desired thread configuration being formed on the stock by rolling or an additional stamping operation. V-shaped notches may be cut or stamped to form the desired flanged head 25. The nail screw 20 could be fabricated from an ordinary box nail merely by rolling or stamping threads on its pointed end and notching its head. It is presently preferred that the head 25 have three flanges in large nail screw cnfigurations, its having been found that when a greater number of flanges are utilized the flanges tend to shear off during driving of the screw nail. In the screw nail embodiment shown in FIG. 3 the radially extending side surfaces of each flange are parallel.
One embodiment of a tool head for driving the nail screw 20 is shown in FIGS. 2, 5, 6 and 7 the tool head being generally indicated by the reference numeral 30. The tool head may be fabricated from a metallic cylinder 31 which during operation rotates about its main axis. It will be seen that the tool head 30 may also reflect a quasi-cylindrical shape in outside cross section such as hexagonal, octagonal or the like. The tool head is relatively compact and designed to replace or supplement the chuck of a pneumatically or electrically operatcd hand held power tool. This embodiment is shown for use with power tools having a male coupling of hexagonal cross section. Accordingly, one end of the cylinder 31 is provided with an axially extending passageway 32 of hexagonal cross section. As shown in FIG. 9 the driving tool head may also be adapted with the male coupling 62. A permanent magnet of identical hexagonal cross section may be force fit into the passageway 32 and pushed to the very end of the passageway to form an end wall of the passageway 32. As shown elsewhere, such end wall may also be of non-magnetic material integrally formed with the body of the driving tool head.
The other end of the metallic cylinder 31 is provided with an axial passageway 33 extending into communication with the passageway 32, whereby the permanent magnet 35 forms an end wall for the passageway 33. The cross section of the passageway 33 is substantially identical to, but slightly greater than, the cross section of the flanged head 25 of the nail screw 20 to allow the nail screw to be inserted, head end first, into the passageway 33 and pushed therein to a driving position wherein the nail screw head is abutting against the permanent magnet 35.
The end of the cylindrical body 31 which contains the passageway 33 defines a tipped portion 36 formed to provide a countersink, the edge surfaces defined by the junction of the passageway 33 side walls with the exterior surfaces being somewhat sharpened. The maximum diameter of the tipped portion 36 may be coincidental with or smaller than the outer diameter of the cylinder 31, thereby forming an annular shoulder, which may be either transverse or sloped at any predetermined angle, for determining the counter-sink or nail head embedding depth and providing automatic withdrawal of the nail screw 20 from the tool head 30, as will be explained with reference to FIGS. 1 and 8. It may be seen that the depth of desired countersink and the form of the counter-sink indentation may be varied in accordance with a preselected definition of the tipped portion 36 and the shoulder 38.
To prepare for operation the tool head 30 is coupled to a hand held power tool 40 by insertion of the male power tool coupling into the passageway 32. In the illustrated embodiment the power tool 40 is of the pneumatic type operated from a pressure tank 41 and coupled thereto by an air hose 42. A tool head 30 is selected in accordance with the size of the nail screw 20 to be driven, it being contemplated that a set of tool heads 30 be available to accommodate various nail screw sizes.
A nail screw 20 is loaded into the tool head merely by bringing the flanges of the nail screw head 25 into register with the passageway 33 and axially inserting the nail screw, head end first, into the passageway until the head 25 abuts against the end wall 82, permanent magnet 35 forming the end wall of the passageway or the reduced cross sectional area 84. This loading operation is very quick and simple, the nail screw being retained in a driving position in the tool head by abutment with the end wall and support over a substantial portion of its length, by magnetic force or by press-fit such as into the members 88 or the reduced cross sectional area 84. i
The loaded power tool 40 is then used somewhat in the manner of a power drill, the pointed tip of the nail screw 20 being pushed against the surface of the pieces to be joined, such as the illustrated wood pieces 45 and 46. Axial pressure is used to start the nail screw, but once the threads are engaged in the wood, then further axial pressure is unnecessary since the screw action of the device tends to pull the nail screw into the wood, the threaded nail screw point acting somewhat like a drill because of its thread configuration. Of course, the power tool must be continually moved forward as the screw nail progresses into the wood in order to prevent the nail screw from being permaturely withdrawn from the tool head. Upon nearing completion of the driving operation, if countersinking is desired, the countersink tip 36 of the tool head is urged into contact with the surface of the wood piece 45, further pressure thereby causing a counter-sinking operation as indicated in FIG. 8. Upon sufficient countersink penetration or contact of the shoulder 38 with the wood surface, axial motion of the power tool is halted and further rotation of the tool head and nail screw causes automatic withdrawal of the nail screw from the tool head as the nail screw penetrates deeper into the wood. Finally, with the tool head flange 38 being lightly head against the wood surface, the nail screw will be completely driven, the head then clearing the countersink tip portion 36 of the tool head. Thus, it is seen that in one operation there are performed the functions of drilling, seating and countersinking. Furthermore, this operation takes no more time than pounding a nail and actually requires less labor, the movement being similar to that of drilling a hole with a power drill.
In FIG. 11 of the drawing there is shown an alternative embodiment of the present invention nail screw,
generally indicated by the reference numeral 50 and differing from the FIG. 3 embodiment primarily in the shape of its head 55. The head 55, is in the general form of a triangular pyramid with its largest crosssection defining one end surface of the nail screw. Therefore, the axial passageway in the tool head for driving this nail screw must be of triangular cross section complementary to the'end of the nail screw.
In FIGS. 9 and 10 of the drawing there are shown various views of an aletemative tool head 60, adapted for driving the nail screw 50. The tool head 60 is illustrated for use with a power tool having a female output coupling, the tool head having a cylindrical body 6 l'with a reduced diameter coaxial cylindrical projection 62 forming the male coupling. The projection 62 may also be threaded, notched, or be of a different cross section in accordance with the requirements of the particular power tool with which it is to be used. It is apparent that the present invention tool head; and may be provided with any type of power tool coupling, either male or female. The other end of the cylinder 61 defines an elongate coaxial passageway 64 partially threaded as shown at 65. Threaded into this passageway is a tubular insert 70 of non-magnetic material having a discshaped permanent magnet secured at one end, the magnet 71 being non rotatably secured into position by means of a stop pin 72. The exterior surface of the insert 70 is sized tofit the passageway ofcylinder 71 and also provided with threads for engagement with the threads 65 of the tool head. Thus, the insert 70.is detachably secured in the cylinder 61 for easy removal or replacement. The interior surface of the tubular insert 70 defines an axial passageway 73 extending to the sur face of the magnet 71 the cross section of the passageway 73 being sized to fit the largest triangular cross section defined by the end of the nail screw 50.
, To prepare this embodiment for use the tool head 60 is coupled to the power tool, such as by insertion of the male coupling 62 into the chuck ,ofa power drill, for example. In this embodiment the cylindrical body 61 may remain on the power tool, replacement of the insert 70 providing the necessary changes for different nail screw sizes. An appropriate insert 70, is selected in accordance with the size of the nail screw 50 to be driven,
or the degree of countersink desired, and the insert then threaded into the end of the cylindrical body 61. Loading and driving of the screw nail proceeds in a manner similar to that hereinabove described using a unitary tool head rather than one with replaceable inserts.
It will be apparent that the illustrative embodiment of the present invention depicted in FIG. 9 may be adapted for use with the other nail screw and coupling embodiment illustrated in the drawings.
Referring now to FIGS. 12 117, there are shown other embodiments of the present invention driving tool head. With particular reference to FIG. 13, there is shown an embodiment of the driving tool head invention wherein the body 76 of the tool head is formed to define a nail screw passageway 78 having an initial cross sectional area at the shoulder 80 only slightly larger than a compatibly sized nail screw head and gradually decreasing over the length of the passageway to define a cross sectional area at the end wall 82 slightly smaller than that of a compatibly sized nail screw head. Such passageway configuration provides a means for holding, by press-fit, the nail screw in substantial axial alignment during introduction at the reduced area 84. The FIGS. 12 and 13 embodiments, as well as other embodiments, may also include the beveledged material exhaust slots 86 formed through the body 76 with the passageway 78 to permit exhaustion of waste materials which may collect in the passageway 78 during nail screw driving or countersinking opera tions. Referring to FIG. 15, it will be seen that the passageway 78 may include the spring-like members 88 between which a nail screw head may be inserted to hold the nail screw in axial alignment during introduction. While the members 88 may be independently fas tened within the passageway 78 by any known method, such as soldering or metal adhesive application, there is shown an integral press-fit metal assembly 90 comprising the end wall abutting member 92 from which extend the members 88, which assembly may be conveniently'inserted in the passageway 78 if desired. While the above embodiments have been described with reference to FIGS. 12 17, only, it will be readily seen that the described portions may also be applied to other embodiments of the present invention depicted in the drawings. For example, the nail screw passageway 78 shown, in FIG. 13 could easily be formed in the present invention embodiment of FIGS. 2, 5 and 9 as could be exhaust slots 86 shown in FIG. 12.
Although the present invention has been described with, a certain degree of particuiarity, it is understood that the disclosure has been made only by way of example and that numerous changes in the details of construction may be resorted. to without departing from the spirit and scope of the invention as hereinafter claimed.
What is claimed is:
1. A tool head for driving a flanged head nail screw comprising:
an elongate substantially cylindrical body;
coupling means for coupling rotary motion to said body on one end of said body;
a splined socket in the end of said body opposite said coupling means, the minor diameter of said splined socket decreasing with respect to distance from the end of said body containing said splined socket whereby the head of a nail screw mating with said splined socket will be held at a point intermediate 7 v 8 the end of said body and the bottom of said splined end of said body containing said socket along the Socket; axis of said body, whereby chips within said socket at least one euttmg edge formed on the end of Sald from the action of said counterbore will be exbody having said splined socket, said cutting edge hausted being at the at the intersection of said socket with said end of said body whereby a counterbore will A tool head for driving a flanged head nail Screw be formed on the end of Said body. and as recited in claim 1 wherein said splined socket is suba slot extending radially from the minor diameter of stamiany Y'ShaPed, the Splines thereof being Substansaid socket to the outer periphery of said body, said tially Of q l gt and eq lly p ced. slot extending a predetermined distance from the 10