EP0236630B1

EP0236630B1 - Wrenching tool

Info

Publication number: EP0236630B1
Application number: EP86309812A
Authority: EP
Inventors: Jozef Ruzicka; Petr O. Ruzicka; Milan Ruzicka
Original assignee: Individual
Current assignee: Individual
Priority date: 1985-12-18
Filing date: 1986-12-16
Publication date: 1994-09-07
Anticipated expiration: 2006-12-16
Also published as: EP0525356B1; EP0236630A1; EP0525356A1; ATE111006T1; CA1327464C; DE3650060D1; DE3650060T2

Abstract

The rotary wrenching tool or spanner (20) has an opening to receive the head (24) of a threaded member. The opening has on the inner surface a number of arcuate concave curves (26), each such surface being defined as locus of points falling a given radial distance (R) from the axis. The opening also has a number of convex curves, each surface being defined as the concave curves. The wrench can be open ended (22) similar to an ordinary spanner or closed (20) similar to a ring spanner.

Description

This invention relates to rotary tools of the type used in rotating or "wrenching" fasteners such as bolts and screws having polygonal (e.g., square or hexagonal) heads. The invention particularly relates to tools capable of wrenching fastener heads designed, sized or marked in various measuring systems such as the metric system, the English or inch system such as the American fractional system (AF and SAE), and the British systems such as BA, BS and Whitworth (W).
The tools have a uniquely configured opening for receiving a polygonal head of a threaded member.
Many countries have adopted the metric measuring system for the manufacture of bolts, screws, nuts and wrenches. Such countries as France, Germany, Italy, Japan, Czechoslovakia and Russia today almost exclusively utilize the metric system for such manufactures. The United States, Canada, England, Australia, New Zealand and the like, use measuring systems based upon both the English (inch) and metric measuring systems.
National standards or specifications have been adopted by many technically developed countries for sockets and other wrenches. These standards, which differ at least in part from one another, include SAE, ASTM, MIL, GGG-W, BS, FS, DIN, JS, CSN, JUS, and GOST. No uniform international standard has yet been accepted, although more than fifteen years have been devoted to the effort to reach a standard acceptable to all technically developed countries. Great Britain, for example, presently uses up to six different systems for marking spanners, sockets and other wrenches. The United States predominantly uses the English (inch) system (AF, ANSI, MIL and SAE) and, to some extent, the metric system (millimeters). The diversity in such standards has limited the development of new types of bolts, nuts and wrenching tools. Periodic reviews and revisions of such standards have not produced the necessary changes to cover rapid development of a new type of wrenches, and the issuance of new, updated standards often takes over fifteen years. Consequently, a vast number of different wrenching tools of various designs, openings and tolerances are manufactured throughout the world. A user is subjected to a never-ending inventory of wrenching tools to accommodate all of the sizes and measuring systems in existence today. This is costly and inconvenient for individuals and for industry in general.
One attempt to simplify this situation is found in U.S. Patent 4,100,824 which desribes a wrench with a non-uniform interior configuration having one set of grooves sized in the English system and another set of grooves sized in the metric system. This patent does not address the problems created through the use of various additional measuring systems. Care needs to be taken with this system to insert the bolt or nut head in the correct set of grooves, and this wrenching system, moreover, generally is not suitable for use in impact or power sockets or in open end wrenches and British sized spanners and sockets.
U.S.Patent 3 027 790 discloses a wrench having several moving parts as adaptors and does not appear to represent a practical solution to the problem, since professionals and serious amateurs appear to prefer solid one-piece wrenching tools with no extraneous parts.
US-A-3 125 910 (Kavalar) discloses a wrench corresponding to the preamble of the appended claim 1, and having an opening to receive a nut or other polygonal head, the opening consisting of inwardly and outwardly projecting lobes. The wrench, in use, applies pressure against flat faces of the nut by means of the inwardly extending lobes contacting the nut faces at specific locations. Moreover, a variance of more than 5 from that specific contact location has deleterious consequences. Kavalar makes no reference or suggestion that the tool disclosed is of any value in meeting the requirement for a wrench for use with polygonal heads sized according to two or more measuring systems. The present invention now provides a means of satisfying that requirement.
Accordingly, the present invention provides a rotary wrenching tool having an opening for receiving a polygonal head of a threaded member, wherein:

the opening has an axis of rotation and has an inner surface comprising a series of first surfaces concave to said axis of rotation and spaced about the circumference of the opening, and a series of second surfaces convex to said axis of rotation and spaced about the circumference of the opening, successive ones of said first surfaces being disposed between successive ones of said second surfaces around the circumference;
each of the first surfaces is arcuate and is defined as the locus of points falling a given radial distance "r" from a first axis "a" itself spaced a distance "r, " from, but parallel to, said axis of rotation;
each of the second surfaces is arcuate and is defined as the locus of points falling a radial distance R from a second axis spaced itself a distance "Ri " from, but parallel to, said axis of rotation; and
the dimensions and dispositions of the second surfaces are such that, in use, the contact made by the wrenching tool with the polygonal head is a contact between the arcuate second surfaces and the sides of the polygonal head of the threaded member;
characterised in that:
each surface that forms part of the inner surface of the opening and is contiguous to an arcuate surface merges tangentially into that arcuate surface; and
the angular relationship between r₁ and R₁ is such that if r is equal to R the wrench includes flat surfaces between and tangentially merging with the first and second surfaces.

There have now been devised, according to the present invention, rotary wrenching tools having the ability to tighten or loosen two or more, for example up to six, different sizes of fasteners, without damage to either tool or fastener.
With regard to the dimensions of the wrenching tool, R₁ desirably is larger than ri, and in the case where each second axis is angularly spaced from at least one next adjacent second axis by 60 °, the ratio R, /r, desirablyexceeds 1.5 and preferably exceeds 2.0. In this case also, R is desirably equal to or greater than r, and the ratio R/r preferably exceeds about 5.0. Also in this embodiment in which each second axis is angularly spaced by 60 from at least one next adjacent second axis, the adjacent arcuate surfaces preferably merge tangentially into one another. The terms "arc" and "arcuate" used herein refer to circles.
The second axes of the embodiments described above may, if desired, be spaced from one another by 45 _°or by 90 _°to thereby provide an opening accommodating square heads of threaded members. Inwardly convex arcuate surfaces of different sizes may be interspersed with one another.
The rotary wrenching tools of the invention preferably have head-contacting interiors sized to strongly and adequately grip polygonal fastener heads sized in two, preferably three, and up to six different nominal sizes. The ratio (determined as described above) for tools accepting square heads ranges from 1.0001 to about 1.1430 and for tools accepting hexagonal heads ranges from 1.0001 to about 1.0600. Also as the wrench opening sizes are varied (for example Figures 17, 18, 19,), the included angle between any adjacent flats preferably is also varied to better accommodate fastener heads sized in different sizing systems.
In a preferred form the wrenching tools of the invention are simple, single piece rotary wrenching tools having uniform interior configurations and no moving parts and which are specifically sized for turning fasteners (nuts, screws, bolts, etc.) having square, hexagonal or other polygonal heads such that one tool size is capable of strongly and adequately fitting polygonal heads nominally sized in at least two and up to six different nominal sizes and up to seven different system markings. By "rotary tool", "spanner" or "wrench", as used herein, reference is made to tools having openings which completely or partially encircle or encompass the polygonal heads of threaded fasteners such as bolts and screws to rotate the fasteners. Thus, such tools may be of the socket variety in which the rotary tool opening completely encircles the head of the threaded member and is moved into such position axially of the threaded member, or may be of the spanner or open-end wrench variety in which the rotary tool opening only partially encircles the head of the threaded member and may be moved into its wrenching position in a direction generally normal to the axis of the threaded member. Rotary tools include such tools as may commonly be referred to as socket wrenches, box-end spanners, ratcheting box-end, open end, nut drivers, flare-nut, lug-nut, crowfoot and combination wrenches, impact and power socket wrenches, flex-head wrenches, etc.
In a preferred form of the invention wrenching tools are adapted for use with threaded members having square heads and are so sized as to accommodate maximum and minimum sized square-headed members such that the maximum ratio of the nominal distance across opposing flats of such maximum and minimum square-headed members ranges from about 1.0053 to about 1.1430. Similarly, wrenching tools adapted for use with threaded members having hexagonal heads are so sized as to accommodate maximum and minimum sized hexagonal headed members such that the maximum ratio of the nominal distance across opposing flats of such maximum and minimum sized members ranges from about 1.0053 to about 1.0600. Visible indicia are preferably carried adjacent each wrench opening, such indicia comprising at least two and preferably three or more specific but different nominal sizes in at least two different sizing systems.
There are now described, by way of example and with reference to the accompanying drawings, a wrenching tool (also referred to as "wrenching system" or "wrench") according to preferred embodiments (Figures 15 - 21) of the present invention, some of those embodiments being described, for the sake of comparison, with reference to wrenching tools (Figures 1 - 14) of the prior art.
In the drawings:

Figure 1 is a broken-away plan view of a conventional two-contact point drive wrench, the wrench flats making contact with corners of a square or hexagonal bolt head as shown in phantom lines;
Figure 2 is a broken-away plan view of a conventional three-contact point drive wrench similar to that of Figure 1;
Figure 3 is a broken-away plan view of a conventional four-contact point drive wrench similar to that of Figures 1 and 2;
Figure 4 is a broken-away plan view of a conventional wrench similar to that of Figure 1 but having internal wrench flats designed for turning square bolt heads;
Figure 5 is a broken-away plan view of a conventional six-driving point wrench described in British Patent 508,761 for use with hexagonal bolt heads and which avoids contact with corners of a bolt head;
Figure 6 is a broken-away plan view of a conventional twelve-contact point drive wrench for turning hexagonal headed bolts;
Figure 7 is a broken-away plan view of a twelve-contact point wrench designed to contact hexagonal bolt heads without corner contact, of the type described in U.S. Patent 3,125,910 (Kavalar);
Figure 8 is a broken-away plan view of a twelve-point drive wrench which does not contact corners of a hexagonal bolt, one type of which is shown in U.S. Patents 3,272,430 and 3,495,485;
Figure 9 is a broken-away plan view of a twelve-contact point wrenching system of the type shown in U.S. Patent 3,079,819;
Figure 10 is a broken-away plan view of a two-contact point wrench driving square and hexagonal nuts;
Figure 11 is a broken-away plan view of a four-contact point wrench similar to that of Figure 10;
Figure 12 is a broken-away plan view of a three-contact point wrench of the type described in U.S.
Patent 3,695,124, used for hexagonal bolt heads and, which does not contact the corners of the heads, in a manner similar to that shown in Figures 10 and 11;
Figure 13 is a broken-away plan view of a six-contact point drive wrench used for hexagonal bolt heads and which does not contact the corners of the heads;
Figure 14 is a broken-away plan view of a twelve-point "spline" drive wrench of the type shown in U.S.
Patent 3,675,516, used for turning splined members and also hexagonal bolt heads;
Figure 15 is a broken-away plan view of a novel six-contact point wrenching tool;
Figure 16 is a broken-away plan view of a novel six-contact point wrenching tool;
Figure 17 is a broken-away plan view of a novel four-contact point drive wrench for turning square bolt heads;
Figure 18 is a broken-away plan view of a novel eight-contact point drive wrench for use with square bolt heads;
Figure 19 is a broken-away plan view of a novel six-contact point drive wrenching system;
Figure 20 is a broken-away plan view of a novel eighteen-contact point drive wrenching system for turning hexagonal bolt heads;
Figure 21 is a broken-away plan view of a novel twenty-four-contact point drive wrench;

To aid in understanding the concept of rotary wrenching tools in general, a brief explanation is given below of the contact that occurs between the working surfaces of a rotary wrenching tool and a nut or bolt head. With reference to the conventional wrench of Figure 1, for example, the wrench (10) has wrench flats (11), (12) which are spaced apart a sufficient distance to loosely accommodate the confronting flat surfaces (13), (14) of a hexagonal bolt, shown in phantom lines. If the wrench is turned in the direction of arrow A, it will be understood that the wrench flats bear against the corners of the bolt head, rather than upon the flat surfaces of the bolt head; this is referred to as "corner contact", and use of wrenches of this type can readily score and round the corners of bolt heads, particularly hexagonal bolt heads. With wrenches of the type shown in Figure 7, on the other hand, the interior surface of the wrench opening makes contact not with the corners of the bolt head but rather at points (actually, lines) along the length of the flat bolt head edges. The rounded lobes (15) of the wrench (16) initially make line contact with the bolt head, but as pressure is applied, the bolt head edges are deformed slightly so that contact between the lobes and the bolt head occurs over a broader surface. Although certain wrench configurations, such as that depicted in Figure 8, have been advertised as providing "flat-to-flat" surface contact with hexagonal bolt heads, it will be understood that tolerances in the manufacture of both the wrench and the bolt heads prevent such contact from in fact being along the full surface of the wrench flats, such contact being in fact a line contact until the bolt head is suitably deformed by sharp edges of the wrench. Note that the wrench of Figure 8, in a manner similar to that shown in Figure 5, employs recessed portions to accommodate corners edges of fastener heads to thereby avoid corner contact with the heads.
With reference to the tools exemplified in the drawings, such tools are characterized as having uniform interior configuration. That is, similarly configured interior surface elements (e.g., lobes) are radially spaced the same distance from the axis of the wrenching tool opening. For example, the lobes (15) depicted in Figure 7 are equally radially spaced from the axis X.
The present invention provides rotary wrenching tools which have no moving parts and which are specifically sized for turning fasteners such as nuts, screws and bolts that have square, hexagonal or other polygonal heads. These wrenching tools are characterized by being capable of strongly and adequately fitting polygonal heads nominally sized in at least two different systems such as, for example, the American Fractional standard ("AF") and the British Standards ("BS", for example), and preferably carrying at least two and preferably three or more suitable size markings in different size systems. That is, the rotary wrenching tools of the invention fit polygonal fastener heads such that scoring or rounding of the heads does not occur even when substantial wrenching torque is applied thereto. Such strong and adequate fitting of the tool to the head of the fastener is such that the application of excessive substantial wrenching torque is more apt to cause physical breakage of the fastener head from the threaded stem of the fastener, or simply cause the deformation ("stripping") of the stem threads. Of particular importance to this embodiment of the invention are those wrenches which have head-confronting surfaces that are contoured to provide recesses opposite corners of the heads to thereby avoid contact with the head corners. Most preferably, the head-confronting surfaces of the rotary tool are provided with inwardly protruding, rounded lobes positioned to encounter the head of a fastening member along flat surfaces of the head, rather than at its corners, the lobe, upon the application of substantial torque, tending to slightly deform the flat surfaces of the head to provide surface-to-surface contact between the wrench and head.
The driving heads of bolts and similar fastening members can be sized in the metric system (e.g., mm) and also in inches using American Fractional ("AF") standards (SAE, MIL, etc.) and British standards such as "BS", "BA" and "W" (Whitworth) measurements. The wrenches preferably are sized so as strongly and adequately accommodate fastener heads of at least two different nominal sizes such that the ratio of the nominal distances across opposing head surfaces falls, in the case of square heads, within the range of about 1.0053 to about 1.1430, and, in the case of hexagonal heads, with the range of about 1.0053 to about 1.0600.
Table I set out below provides a non-inclusive, exemplary list of nominal head openings and size combinations for square and hexagonal head fasteners. Referring, for ease of explanation, to the first entry in the table, this entry describes a wrench which will fully and adequately engage the polygonal head of a threaded fastener that has the nominal dimensions of 1.5mm & 1/16 (AF, U.S. standard) & 16 BA (British standard). As shown in the table, 1/16 inches converts to 1.5875 millimeters. 16 BA, in the British standard, corresponds to 1.4224mm. 1.5mm, in the metric system, is, of course, 1.5mm. The maximum ratio of the maximum nominal distance across flats (1.5875) to the minimum nominal distance across flats (1.4224) is 1.1161, and this is recorded in the final column of the table. As further explanation, the last entry in the table refers to a fastener head having a nominal distance across opposing flats of 220mm. The wrench of the invention, suitably sized, also fully and adequately fits fastener heads sized in the U.S. American Fractional system as 8 5/8" & 8 3/4". The latter nominal values correspond to 219.0731mm and 222.2481mm, respectively. The maximum ratio of the maximum nominal size to the minimum nominal size hence is 222.2481/219.0731, or 1.0145. The ratios thus referred to are calculated according to the following formula:
The rotary wrenching tools of the invention can, for example, bear visually readable markings indicating the at least two and preferably three different head sizes for which they were designed. For example, the first wrench appearing in Table I may be marked "1.5 mm & 1/16in. & 16 BA". The table has been computed using international (ISO) and many national standards and specifications from the United States (SAE, ANSI, MIL, ASTM), British (BS), German (DIN), France (FS), Yogoslavia (JUS), Japan (JS) and specifications from various manufacturers in the United States, England, France, Germany, Canada, Japan, Italy, Sweden, Spain, Czechoslavakia, Yugoslavia, Taiwan, China, Brazil, etc.
With reference to Figures 3-21, each figure shows positions of a bolt head within the gripping opening of a rotary wrenching tool, the bolt head positions shown in phantom lines referring to the smallest bolt head that can be fully and adequately gripped by the tool. Certain of the Figures also show a wrenching tool in both a socket form (wherein a full circle in either solid or dotted lines appears about the bolt head) or in open-ended wrench form. In Figure 3, for example, a socket is shown in dotted lines as (17), the open-ended wrenching tool version being shown in solid lines as (18). In Figures 4, 5, 7, 9-11, 13-18, 20 and 21, similarly, the socket embodiment is shown in solid lines as (20) and the open-ended embodiment is shown in phantom lines as (22). Further, alternate positions for the ends of the open-ended embodiments may be varied, and several positions are shown, for example, in Figure 14.
The following non-limiting examples will serve to more clearly illustrate various further embodiments of the invention.

Example I

With reference to the embodiment shown in Figure 16, socket and open-end rotary wrenching tools shown generally at (20) and (22) are sized so as to strongly and adequately grip the hexagonal heads of threaded fasteners sized 4 mm a 5/32" & 8 BA, giving a ratio of 1.0363. The wrench of Figure 16, as shown from the drawing, has an axis of rotation X that extends normal to the plane of the paper and has an opening for receiving the polygonal head of a threaded member, in this case, a hexagonal head shown as "H". The opening has an inner, head-confronting surface comprising a series of arcuate first surfaces (24) concave to the axis of the opening and spaced about the circumference of the opening. Each such first surface is defined generally as the locus of points falling a given radial distance r from a first axis "a" that is itself spaced a distance ri from, but parallel to, the axis X of the opening. Between the arcuate first surfaces (24) are positioned a series of arcuate second surfaces (26) which are convex to the axis of the opening and are spaced about its circumference, each such second arcuate surface being defined general as the locus of points falling a radial distance R from a second axis A which is itself spaced a distance R₁ from, but parallel to, the axis X of the opening. Each surface that forms the opening and that is contiguous to an arcuate surface tangentially merges into that arcuate surface. R₁ preferably is larger than ri , and the ratio R, /r, desirably exceeds 1.5 and preferably exceeds 2.0. The arcuate second surfaces (26), it will be noted, form "lobes" having rounded surfaces for making contact with the flats of a hexagonal head of a threaded member. One such member, designated "h," is shown in operative contact with the lobes. Each second axis A is angularly spaced from at least one next adjacent second axis A by 60 °.
With further reference to Figure 16, rotary wrenching tools of this general configuration may be manufactured as socket, box-end, open-end, flare nut, nut driver and crowfoot wrenches, sized for receiving hexagonal fastener heads nominally sized as follows:

10 mm & 3/8" (AF) (ratio of 1.0499);
11 mm & 7/16" (AF) & 3/16 W (Whitworth) & 1/4 BS (ratio of 1.0275);
19 mm & 3/4" (AF) & 3/8 W & 7/16 BS (ratio of 1.0563).

Similarly, rotary wrenching tools configured as shown in Figure 16 may be designed as socket, box-end and crowfoot wrenches, sized to accommodate hexagonal fastener heads nominally sized as 28 mm & 27 mm & 1 1/16" (AF) & 1 1/8" (AF) & 5/8 W & 11/16 BS, the wrench having a ratio, as defined above, of 1.0588. Other wrenching tools configured as shown in Figure 16 may be provided as socket and box-end tools sized to receive hexagonal fastener heads nominally sized as 32 mm & 33 mm & 1 5/16" (AF) & 1 1/4" (AF) & 3/4 W & 7/8 BS, the wrench having a ratio of 1.0500. Yet another wrench configured as shown in Figure 16 may be provided as a socket wrench sized to receive hexagonal fastener heads nominally sized as 220 mm & 8 5/8" (AF) & 8 3/4" (AF), the ratio of which is 1.0145.
If the ratio R/r is substantially greater than 1.0, preferably exceeding about 5.0, and if R₁ is substantially larger than ri , the particularly desirable configuration of the wrench shown in Figure 15 is obtained. This embodiment makes use of large, gently rounded, inwardly projecting lobes (26) separated by rounded recessed arcuate portions (24), the latter providing room to accommodate corners of the head of a threaded member without coming into corner contact therewith. Again, each surface forming the opening that is contiguous to an arcuate surface tangentially merges into that surface.

Example 11

Socket and Box-End rotary wrenching tools configured as shown in Figure 15 are sized to receive hexagonal heads of threaded members nominally sized 35 mm & 34 mm & 1 3/8" (AF) & 1 5/16" (AF) & 13/16W & 15/16 BS, the tool having a ratio, as defined above, of 1.0591. Similarly, socket wrenches may be designed in accordance with Figure 15 and sized to receive hexagonal heads of threaded fasteners nominally sized as follows:

a) 105 mm & 4 3/16" (AF) & 4 1/8" (AF) & 2 3/4 W & 3 BS, the ratio being 1.0152;
b) 140 mm & 5 5/8" (AF) & 5 1/2" (AF) & 3 3/4 W & 4 BS, the ratio of which wrench is 1.0227.
c) 200 mm & 7 7/8" (AF) & 8" (AF), with a ratio of 1.0160.

If the wrenching tool shown in Figure 16 in which R is approximately equal to r is modified so that R₁ is approximately equal to ri, then tools of the general type shown in Figures 18, 20 and 21 are obtained. Referring to Figure 18, eight contact points or lobes (26) are provided. This wrenching tool is particularly adapted for receiving square heads of threaded fasteners. The inner surface of the tool includes portions designated (30) which are generally flat surfaces and that extend between the arcuate first and second surfaces. Such flat surfaces (30) may be oriented so as to come into generally surface-to-surface contact with the flats of a threaded member head, as shown in Figure 18, the angular dimensions appearing in Figure 18 being adapted to promote such surface-to-surface contact. Figure 20 and 21 show tools somewhat similar to that shown in Figure 18, except that the tool of Figure 20 has its lobes angularly spaced 20 apart and the tool of Figure 21 has its lobes spaced angularly 15 apart. Note is made that the spacing between adjacent second axes A of the embodiments of Figures 18, 20 and 21 are generally less than 3R in which R is as described above in connection with Figure 16.

Example III

Socket and box-end rotary wrenching tools may be designed and manufactured in the configuration shown in Figure 18 and specifically sized in accordance with the invention to receive square heads of threaded fasteners nominally sized 13 mm & 1/2" (AF) & 1/4 W & 5/16 BS, and having a ratio of 1.0500. Similarly, socket, box-end and open-end wrenching tools may be designed and manufactured in accordance with the configuration of Figure 18 and sized for receiving square-headed fasteners nominally sized 16 mm & 5/8", and having a ratio of 1.0079. The same socket and box-end tools may be designed and manufactured in accordance with the configurations of Figures 20 and 21 and sized to receive hexagonal fastener heads nominally sized 16 mm & 5/8" (AF), the tools having a ratio of 1.0079.
Using the nomenclature described above in connection with Figure 16, the rotary wrenching tool of Figure 19 is provided with inwardly convex lobes (26) formed generally on radii R swung about axes A, the latter axes being angularly spaced about the axis of rotation X by 600. Inwardly concave surfaces (24) are formed on radii r swung about axes a and positioned such that two spaced inwardly concave arcuate surfaces are positioned between each of the inwardly convex surfaces (26) forming lobes of the wrench. Generally flat surface portions (30) extend between adjacent inwardly concave and convex surfaces (24) and (26), the inwardly concave surfaces being joined by a surface (32) that is formed on a radius about the axis of rotation X. Again, each surface that forms the wrench opening and that is contiguous to an arcuate surface tangentially merges into that arcuate surface. The wrenching tool of Figure 19 has head-receiving openings configured to provide combinations of line, surface and flat-to-flat contact with differently sized fastener heads.

Example IV

A socket wrenching tool designed and manufactured to have the configuration shown in Figure 19 is specifically sized to receive hexagonal head fasteners nominally sized at 5 mm & 3/16" (AF) & 6 BA, the tool having a ratio of 1.0499. A similar tool is sized to receive hexagonal fastener nuts nominally sized 100 mm & 3 7/8" (AF) & 2 1/2 W & 2 3/4 BS, the tool having a ratio of 1.0160. Similarly, a wrenching tool fabricated in accordance with the configuration of Figure 19 may be specifically sized to receive hexagonal head fasteners nominally sized at 14 mm & 9/16" (AF), the tool having a ratio of 1.0205. Socket and box-end wrenching tools configured as in Figure 19 may be sized to specifically receive hexagonal fastener heads nominally sized 75 mm & 3" (AF) & 2 15/16" (AF), and having a ratio of 1.0213.
An embodiment similar to that described above in connection with Figure 19 is shown in Figure 17, this rotary tool having internally projecting lobes (26) spaced 90 from one another and having a pair of inwardly concave arcuate surfaces (24) formed between each pair of inwardly projecting lobes (26). Generally flat interior surfaces (30) extend between the arcuate surfaces and merge tangentially into such arcuate surfaces.

Example V

Socket, box-end and open-end wrenching tools may be manufactured in accordance with the configuration shown in Figure 17 and sized to receive square heads of threaded fasteners nominally sized as follows:

a) 11 mm & 7/16" (AF) & 0 BA (ratio of 1.0593)
b) 14 mm & 9/16" (AF) & 1/4 W & 5/16 BS (ratio of 1.0714)
c) 16 mm & 15 mm & 14 mm & 9/16" (AF) & 5/8" (AF) & 5/16 W & 3/8 BS (ratio of 1.1429).

Preferably, the wrenching tools exemplified in Figures 15-21 likewise carry markings adjacent each tool opening identifying at least two and preferably three or more different fastener head sizes that the opening will strongly and adequately engage. Exemplary markings are shown in Figure 16, the markings (4 mm & 5/32 AF & 8 BA) being stamped, in this example, onto or into the handle of the tool. Rotary wrenching tools in the form of sockets would normally have markings on the outer socket surfaces.
While preferred embodiments of the present invention has been described, it should be understood that various changes, adaptations and modifications may be made therein without departing from the invention and the scope of the appended claims.

Claims

1. A rotary wrenching tool having an opening for receiving a polygonal head of a threaded member, wherein:

the opening has an axis of rotation (X) and has an inner surface comprising a series of first surfaces (24) concave to said axis of rotation and spaced about the circumference of the opening, and a series of second surfaces (26) convex to said axis of rotation and spaced about the circumference of the opening, successive ones of said first surfaces (24) being disposed between successive ones of said second surfaces (26) around the circumference;

each of the first surfaces (24) is arcuate and is defined as the locus of points falling a given radial distance "r" from a first axis "a" itself spaced a distance "r, from, but parallel to, said axis of rotation (X);

each of the second surfaces (26) is arcuate and is defined as the locus of points falling a radial distance R from a second axis (A) spaced itself a distance "Ri from, but parallel to, said axis of rotation (X); and

the dimensions and dispositions of the second surfaces (26) are such that, in use, the contact made by the wrenching tool with the polygonal head is a contact between the arcuate second surfaces and the sides of the polygonal head of the threaded member; characterised in that:

each surface that forms part of the inner surface of the opening and is contiguous to an arcuate surface merges tangentially into that arcuate surface; and

the angular relationship between r₁ and R₁ is such that if r is equal to R the wrench includes flat surfaces between and tangentially merging with the first and second surfaces.

2. A tool according to Claim 1, wherein r and R are unequal and said inner surface includes flat surfaces (30) each disposed between and tangentially merging with one of said first surfaces (24) and one of said second surfaces (26).

3. A tool according to Claim 1 or 2, wherein the first (24) and second (26) surfaces are so disposed relative to said inner surface that, in use, each of the second surfaces contacts the respective adjacent side of the polygonal head substantially midway between the corners of that side.

4. A tool according to Claim 1, 2 or 3, in which each second axis (A) is angularly spaced from at least one next adjacent second axis by 60 _°.

5. A tool according to Claim 4, wherein R₁ is greater than ri.

6. A tool according to Claim 5, wherein the ratio Ri /ri is greater than 1.5.

7. A tool according to Claim 4, wherein R is equal to or greater than r.

8. A tool according to Claim 7, wherein the ratio R/r is greater than 5.0.

9. A tool according to Claim 1, wherein the series of second arcuate surfaces (26) is configured and arranged to contact the flats of the threaded member head to apply torque thereto, the tool being sized to engage the heads of threaded members that are sized in at least two different nominal sizes such that the ratio of the maximum and minimum of said nominal sizes ranges from about 1.0053 to about 1.1430 for square heads, and from about 1.0053 to about 1.0600 for hexagonal heads.

10. A tool according to Claim 1, wherein said opening is sized to engage the heads of threaded members sized in at least two different nominal sizes such that the ratio of the nominal distance across opposing flats of such at least two differently sized heads ranges from 1.0001 to about 1.1430 for square heads and from 1.0001 to about 1.0600 for hexagonal heads.

11. A tool according to Claim 10, wherein said tool carries, adjacent its opening, visible indicia identifying the at least two different nominal sizes.

12. A tool according to Claim 11, wherein said at least two different nominal sizes are expressed in at least two measurement systems.

13. A tool according to Claim 12, wherein said at least two different nominal sizes are as shown in any of the horizontal entries of the following table: