Patent ID: 12228158

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Although the present invention will be described with reference to the embodiments shown in the drawings, it should be understood that the present invention may have alternate forms. In addition, any suitable size, shape or type of elements or materials could be used. Like reference numerals throughout this specification refer to similar features throughout the figures.

Refer now toFIGS.1through3, there being shown a fastener recess according to an example embodiment. The fastener20includes a shank24having a central longitudinal axis26. A head22is positioned at an end25of the shank24. The head22has a six lobed star recess40centered on the axis26. The recess40has six wings42radiating outwardly from the axis26. The recess40has a recess outer radius57defined by a radial distance from the axis26to the outer-most extent of the wings. Each of the wings42has an installation driving surface43and a removal driving surface44(collectively drive walls) which are separated by a wing outer end wall41. The wing driving surfaces43,44are constructed in substantially parallel alignment with the central longitudinal axis26.

The installation driving surface43and removal driving surface44of adjacent wings42are separated by a respective transition contour45, the transition contour forming the radially inward-most portions of the wings42. A wedge is formed in the transition contour to present a tapered interface surface50. The interface surface50is a non-driving surface. Each interface surface50has a top51, a bottom52and a pair of opposed edges53,55. Each opposed edge53,55creates a transition from each installation and removal surfaces to the interface surface. The advantages of the edges53,55will be discussed below. The width58of the interface surface tapers from wider at the top51of the interface surface, which is shown proximate the top48of the recess40to narrower at the bottom52of the interface surface, which is shown proximate the bottom46of the recess40.

The recess extends into the head22to a recess bottom46, which may include a bottom chamfer cone49transitioning from interface surfaces50and the bottom of the drive walls43,44and wing outer end walls41to the recess bottom46. There is a top chamfer cone47transitioning from the head top surface21to the top48of the recess. However, alternative embodiments may not include top chamfer cone47. It should be noted that in alternative embodiments the top51and bottom52of the interface surface need not be proximate to the top48and bottom46of the recess40, respectively. In such embodiments the top51and bottom52of each interface surface may be offset from the top48and bottom46of the recess, respectively.

The interface surfaces50are positioned a root (or bottom) radial distance56from the axis26at the bottom52of the interface surface. The root radial distance defines the recess inner radius56. The interface surface50is positioned a top radial distance59from the axis26at the top51of the interface surface. The top radial distance59is larger than the recess inner radius (root or bottom radial distance)56. The ratio of the recess inner radius56to the recess outer radius57is from about 0.60 to about 0.65. In another example, the ratio of the recess inner radius56to the recess outer radius57is from 0.60 to 0.65. In one example, the ratio of the recess inner radius56to the recess outer radius57is about 0.64 and in another example is equal to 0.64.

The tapered interface surface50is, in one example, concave to the axis26. However, the tapered interface surface may also be flat. The tapered interface surface50may also be alternative shapes provided edges53,55are formed. In one particular concave configuration, the taper interface surface50has a radius of curvature equal to the radial distance from the axis26to the interface surface50. That is, the radius of curvature of the taper interface surface50decreases from the top51of interface50to the bottom52of interface50. In an alternative embodiment, the radius of curvature of the concave taper interface surface50is greater than distance from the axis to the interface surface. In another alternative embodiment, each portion of the concave interface surface is positioned a radial distance greater than or equal to the radial distance from the axis26to the transition contour45at the interface surface edges53,55.

The interface surface50is tapered at a taper angle54(FIG.3) with respect to the axis26from about one half degree (0.5°) to about twelve degrees (12°). In one particular embodiment, the taper angle54is preferably from about four degrees (4°) to about eight degrees (8°), and more preferably about six degrees (6°).

FIGS.1through3show taper interface surfaces50formed between every pair of adjacent wings42. However, in some applications, it may be advantageous to construct the interference contours between only selected pairs, i.e., a subset, of transition contours with the understanding that some misalignment may commonly occur. This can be avoided to some extent, for example, in multi lobed configurations, by constructing the interference contours symmetrically about the recess, such as between opposing pairs of wings, between diametrically opposed pairs of wings, between every other pair of wings, or in triangular configurations.

FIG.4illustrates an example of a standard hexalobular threaded fastener having straight walled drive surfaces of the prior art. One example standard hexalobular recess, also referred to as a Torx® recess, are those fasteners made in accordance with the ISO 10664:2014 and NAS1800 (REV. 4) standards and each of those standards are incorporated by reference herein in their entirety. Each size of a standard hexalobular recess has a correspondingly mated standard hexalobular driver. Another example of a standard six lobed recess, and corresponding driver, is described in the Hughes '795 patent. Each of these recess together will be referred to herein as example standard six lobed recesses and their corresponding drivers as example standard six lobed drivers.

The term “straight walled drive surfaces” may be used herein to refer to fastener systems in which the driving surfaces are substantially in alignment, i.e., parallel with the longitudinal axis of the fastener. It is accepted in the fastener industry that statements, such as “parallel alignment” are subject to some deviation tolerances, as it is understood that such alignment is subject to manufacturing tolerances and may vary slightly in actual practice. In particular,FIG.4illustrates an example standard hexalobular recess, which is also described in the Hughes '795 patent (FIG.2, element30). With reference toFIG.4of the present application, fastener systems with a standard hexalobular recess are constructed having a fastener120and a mating driver bit (not shown). The fastener120is constructed having a head122and a threaded shank (not shown). In this example, a hexalobular configured recess140is formed in the head122with drive surfaces aligned in parallel with the axis126of the fastener120(straight walled). The recess140has a recess outer radius157defined by a radial distance from the axis126to the outer-most extent of the wings142. Installation and removal surfaces143,144of adjacent wings are separated by transition contours145and installation and removal surfaces143,144of the same wing are each separated by a wing outer end wall141. The recess has a recess inner radius156defined by the radial distance from the axis126to the transition contours145. The ratio of the recess inner radius156to the recess outer radius157of the standard hexalobular driver is between 0.70-0.75 (depending on the size of the driver), see, for example, Shinjo '334, ISO 10664:2014, and NAS1800 (REV. 4) standards, which is larger than the ratio of the recess inner radius56to the recess outer radius57of recess40of the present application. As will be discussed below, the smaller recess inner radius56to recess outer radius57ratio of example recess40results in a number of advantageous benefits including improved torque per lobe of a mated driver.

FIG.5is a schematic view showing the recess40profile ofFIG.2(an example recess of the present application) overlaid with the recess140profile ofFIG.4(a standard hexalobular recess).FIG.6is an expanded view of detail VI ofFIG.5. The contour of the recess40, in particular the contour of bottom52of the interface surface50, is shown inFIGS.5and6in dotted lines where it overlaps with the contour of the standard recess140. Although, in this particular illustration, the geometry of recess140is similar to the hexalobular type fastener systems of the Reiland reference cited above, it is intended only as an example of the use of the subject invention in comparison to a standard recess straight walled recess.FIGS.5and6are, of course, not intended to indicate that both recesses may be used at the same time, but only to illustrate the relative position of the example recess40and standard recess140features.

The interface surfaces50of recess40extends closer (radially) to axis26as compared to the transition contours145of recess140(the bottom52of the interface surface50is shown as a dotted line). Therefore, the inner radius156(FIG.4) of recess140is larger than the inner radius56(FIG.2) of recess40. In addition the wing outer walls41of recess40extends further (radially) from axis26as compared to the transition wing outer walls141of recess140. Therefore, the outer radius157(FIG.4) of recess140is smaller than the outer radius57(FIG.2) of recess40. Each of these features, i.e., the smaller inner radius56and larger outer radius57result in an increased drive wall and provides an improved driver to recess driving torque per lobe. This feature will be discussed below with reference toFIG.9.

FIG.7shows a top view of a standard hexalobular driver220mated with a standard hexalobular recess140. The driver220has a bit end which is shown in cross section. The driver and bit end will be referred together as the driver220. The driver220includes features that match those of the standard recess140including, for example, a central longitudinal axis226, a central portion, and a plurality of lobes242radiating outwardly from the central portion which match the recess wings142. Each of the lobes242have corresponding installation and removal surfaces243,244. In addition, the driver220also includes a transition contour245located between adjacent lobes242and lobe outer end walls241located between installation and removal surfaces243,244of the same lobe242. Each of the surfaces of the lobes242are constructed in parallel alignment with the driver longitudinal axis226.

As noted above, and as a practical matter, in order to enable the standard hexalobular driver220to be inserted into the standard hexalobular recess140, there necessarily must be some clearance250between the two. The clearance is the same around the circumference of the driver220.

FIG.8is a view taken along section line VIII-VIII ofFIG.7. In addition to the standard hexalobular driver220and the standard hexalobular recess140each having straight drive walls, each of the recess transition contour145and driver transition contour245are straight walled, i.e., each are parallel (within machining tolerances) with respect to axis126. Therefore, the clearance250remains constant, provided the standard driver220is coaxial with the standard recess140, and will not enhance the stability or frictional engagement of the driver/recess engagement. Although the clearance250allows the standard driver220to be easily inserted into the standard recess140, the driver220is easily accidently misaligned or rocked in the recess140(axis226is not aligned with axis126). Rocking contributes to concentrating forces on the screw head in localized areas with resulting high localized stresses and unstable alignment. Such localized high stress can plastically deform the recess, forming ramps or other deformations that result in premature, unintended disengagement of the driver from the recess and cause cam-out and driver/recess damage.

FIG.9shows the same standard hexalobular driver220in a mated engagement with an example recess40. The example recess40is configured to receive in a mated engagement any driver made to correspond to the hexalobular recess standards discussed above. As shown inFIG.2, the recess40is constructed with a tapered interference surface50formed in the “B” dimension surface of the recess transition contour45. As discussed earlier, the inner radius56(FIG.2) of recess40is smaller than the inner radius156(FIG.4) of the standard hexalobular recess. This is a result of the tapered interface surface/wedge50being tapered toward the axis26. Further, the recess inner radius56is smaller than the top radial distance59.

The recess is narrowed relative to the standard hexalobular recess140(FIG.7) to provide a frictional engagement when the fastener20and driver220are in the mated engagement. The driver220has an inner radius256greater than recess inner radius56and less then top radial distance59resulting in a negative clearance, i.e., interference at interface regions302,304, discussed below. As shown, the “A” dimension is also enlarged relative to the standard hexalobular recess140(FIG.7) in order to allow greater compatibility with other standard six lobed drivers, for example those described in the Hughes '795 patent. However, in alternative embodiments only the “B” dimension is narrowed and the “A” dimension is held to the standard recess size for a fastener of the type illustrated inFIG.4, which may improve the stability of the alignment of standard hexalobular drivers at the expense of additional compatibility.

With continuing reference toFIGS.9and10, the tapered interface surfaces50are constructed to provide a significant frictional engagement (“stick fit”) at edges53,55resulting in two separate interface regions302,304. Because opposed edge53,55are at the transition from each installation and removal surfaces to the interface surface, less material is required to deform upon insertion of a driver to acquire a sufficient stick-fit. Contacting in a lower portion of the recess also provides for a smaller area of contact also improving stick-fit. The two interface regions302,304provide an increase in the stability of the contact between the recess40and driver220by providing two points of stability at each interface surface50, thus improving axial alignment and reducing the risk of cam out. By having two interface regions as opposed to a single line or surface contact better stability is provided. The stick fit is created where the straight walled transition contour245contacts tapered interface surface50. It should be noted that some incline in the driver wall may still provide sufficient stick fit, provided there is sufficient contact at interface regions302,304. The improved stick fit of the example recess40will increase the speed of application of fasteners to the work piece as well as decrease cam-out and driver/recess damage. The degree of stick fit can be adjusted during manufacturing of the recess by adjusting the taper angle54. Each interface region302,304may be various combinations of point and line contacts along edges53,55depending on the particular configuration of the standard six lobed driver. Regardless of the type of contact, there are two interface regions302,304between each tapered interface surface50and driver transition contour245. The two interface regions302,304provide increased stability to the mated engagement of the driver bit and the recess as compared to prior known recesses by helping minimize rocking of the driver within the recess, thus greatly improving axial alignment and engagement of the lobes with the wings. This is particularly useful when the fastener20is non-uniform. Non-uniformity may occur due to a number of reasons. Examples include, but are not limited to, machine tolerances during manufacturing, un-even plating, uneven coatings, painting after fastener insertion, or deformation during insertion or previous installation or removal cycles. Example coatings include, but are not limited to, electro-zinc & clear, electro-zinc & yellow, electro-zinc & wax, mechanical zinc & clear, mechanical zinc & yellow, black phosphate, black phosphate and oil, oil, wax, nickel, cadmium & wax, hot-dip galvanized, dacrotizing. It should be noted that in some examples, such as when the driver and fastener are not in complete axial alignment or due to manufacturing tolerance in use there may not be established two interface regions in each and every recess wing. Nevertheless, stick-fit and stability advantages may still be realized with sufficient interface regions throughout the mated engagement.

In addition to the increased stability provided by the frictional interface at the interface regions302,304, the inner radius56of recess40is smaller than the inner radius156of the standard hexalobular recess140. That smaller inner radius56in combination with the tapered interface surface50results in contact with the driver closer to the center axis226. This provides additional drive wall for transferring torque as shown as driver lobe engagement length310. This results in a drive-wall-ratio of the driver lobe engagement length310to “AT” dimension of from about 0.15 to about 0.21. In one particular embodiment, the drive-wall-ratio is preferably from about 0.17 to about 0.19, and more preferably about 0.18. An increased drive-wall-ratio improves bit to recess driving torque per lobe. This increase drive-wall-ratio is an advantage as compared to standard six lobe recess that utilize a 0.11 drive-wall-ratio according to the hexalobular recess standards when mated with a standard hexalobular driver

FIG.10is a view taken along section line X-X ofFIG.9through diametrically opposed interface regions302. It shows the frictional engagement between the driver bit end and the tapered interface surface50at interface region302occurs in the lower part of the recess. In an alternative embodiment, the tapered interface surface50at interface region304occurs in the lower one third of the recess. A small clearance310between the driver220and the recess40is provided upon mating to ensure contact at interface regions302,304instead of bottoming out, to allow clearance for plating build up in the bottom of the recess, and also to prevent damage to the driver220tip.

FIGS.11-12shows another standard six lobed driver420, namely the six lobed driver described in the Hughes '795 patent, in mating engagement with recess40. Because of the improved configuration of recess40, fastener20is able to provide mating engagement with multiple six lobed drivers, including the Hughes '795 patent driver. The driver420includes a central longitudinal axis426, a central portion, and a plurality of lobes442radiating outwardly from the central portion. Adjacent lobes442are separated by transition contours445. The lobes442have been expanded in the “AH” dimension between opposing lobe outer end walls441as compared to the standard hexalobular driver220and as described in the Hughes '795 patent.

The driver420has an inner radius456greater than recess inner radius56(FIG.2) and less then top radial distance59(FIGS.2-3) resulting in a negative clearance, i.e., interference at interface regions402,404. The driver420to recess40mated engagement provides similar advantages as those described with reference toFIGS.9and10including, but not limited to, decreased rocking and an increased drive-wall-ratio that improves bit to recess driving torque per lobe.

FIG.12is a view taken along section line XII-XII ofFIG.11through diametrically opposed interface regions402. It shows the frictional engagement between the driver bit end and the tapered interface surface50at interface region402occurs in the lower part of the recess. In an alternative embodiment, the tapered interface surface50at interface region304occurs in the lower one third of the recess. A small clearance410between the driver220and the recess40is provided upon mating for the same reasons discussed with reference toFIG.10.

The above features may be applied with similar results to other straight walled fastener systems. As another embodiment, the spiral drive system of the cited standard spiral driver patents may be improved upon by constructing a tapered interface surface/wedge on the opposing “B” dimension transition contours.

For example, shown in TABLE 1 are example “A” and “B” dimensions at the outermost portion of the wing and at the transition contour, respectively, in inches. Such drivers and corresponding recesses may be formed according to SAE International standard AS6305 (issued 2017-01) and are available from The Phillips Screw Company™ under the drive system MORTORQ® Spiral. SAE International standard AS6305 (issued 2017-01) is incorporated by reference in its entirety herein.

TABLE 1Recess “A”Recess “B”Driver “B”DimensionDimensionDimension(diameter at(diameter recess(diameter atoutermosttransitionthe driverDRIVEportion of the wing)contour)transition contour)SIZE(inches) (MAX)(inches) (NOM)(inches)000.0750.0355.032500.1230.0585.05410.1724.0821.07791.2425.1141.10912.3100.1460.13993.3557.1676.16044.4305.2030.19415.5083.2399.22956.5958.2811.26947.8023.3787.3655

An improved recess, in accordance with the present disclosure, that would correspond to the standard Stacy driver can be constructed with disclosed interface surfaces/wedges such that the driver bit end has a radius at the transition contour (half of the driver “B” dimension), which is greater than the recess root radial distance of the improved recess and less than the improved recess top radial distance. This embodiment will not be described further, since its operation and construction can be obtained from the above description.

The recesses of the present application may be manufactured in a conventional two-blow header machine. The punch typically will be formed to include a body and a nib adapted to form the head of the fastener with the disclosed corresponding recess (FIGS.1-3and9-11). Punches may be formed according to conventional punch-forming techniques such as use of hobbing dies. Drivers in accordance with the invention also can be manufactured using conventional techniques, such as by stamping a driver blank with one or more shaped dies to form the desired shape wings or, by milling the driver bit using specially shaped milling cutters.

With reference toFIGS.13-16, disclosed example recesses may be formed by a heading punch adapted to form the head of the fastener with the disclosed corresponding recess. The recess can be formed in conventional heading techniques in, for example, a two blow header.FIGS.13-16illustrate a punch520configured to form example disclosed recess40. The punch is a positive corresponding to the negative of the recess40embodiments described with respect toFIGS.1-3and9-11. Thus, features and dimensions described with reference to disclosed punch520are also applicable to corresponding recess40features and embodiments and vice versa.

The punch includes body portion (not shown) having a face (not shown) and an integral nib540that protrudes from the face. The nib540is the complement of the shape of the recess and the face of the punch is of complementary shape to that of the intended screw head, shown inFIG.3as a flathead. The nib540includes a top chamfer cone forming portion547, which has a chamfer angle564. The nib540has a six lobed star configuration centered on the axis526. The nib540has six wing forming portions542radiating outwardly from the axis526. The nib540has a nib outer radius557defined by a radial distance from the axis526to the outer-most extent of the wing forming portions542. Each of the wing forming portions542has an installation driving surface forming portion543and a removal driving surface forming portion544(collectively drive wall forming portions) which are separated by a wing outer end wall forming portion541. The wing outer end wall forming portion541have a depth566. The wing driving surface forming portions543,544are constructed in substantially parallel alignment with the central longitudinal axis526.

The installation driving surface forming portion543and removal driving surface forming portion544of adjacent wing forming portions542are separated by a respective transition contour forming portion545, the transition contour forming portion forming the radially inward-most portions of the wing forming portions542. A wedge forming portion is formed in the transition contour forming portion545to present a tapered interface surface forming portion550. The interface surface forming portion550forms a non-driving surface. An additional benefit of the location of the interface surface forming portion550is that interface surface50is easier to form with a punch at the “B” dimension as compared to, for example, forming the recess in the “A” dimension, for example the recess of the Hughes '795 patent. Forming the interface surface on the “B” dimension has less risk that the material outside the wing will blow out during manufacture.

Each interface surface forming portion550has a top forming portion551, a bottom forming portion552and a pair of opposed edge forming portions553,555. The advantages of the edge forming portions553,555were discussed above with reference to opposed edges53and55of recess40. Further, because the edges53and55are tapered to a point proximate the bottom46of the recess40, in this example, by edge forming portions553,555, the punch520is capable of removing more material and making the process of forming the recess more efficient. The width558of the interface surface forming portions550taper from wider at the top forming portion551of the interface surface, which is shown proximate the top forming portion548of the recess540, to narrower at the bottom forming portion552of the interface surface forming portion550, which is shown proximate the bottom forming portion546of the recess540.

The nib540extends to a recess bottom forming portion546, which may include a bottom chamfer cone forming portion549transitioning from interface surface forming portions550and the bottom forming portions of the drive wall forming portions543,544and wing outer end wall forming portions541to the recess bottom forming portion546. The bottom chamfer cone forming portion has a chamfer angle562. There is a top chamfer cone forming portion547transitioning from the body portion top forming portion548of the recess. However, alternative embodiments may not include top chamfer cone forming portion547. It should be noted that in alternative embodiments the top forming portion551and bottom forming portion552of the interface surface forming portion need not be proximate to the top forming portion548and bottom forming portion546of the recess forming portion540, respectively. In such embodiments the top forming portion551and bottom forming portion552of each interface surface forming portion may be offset from the top forming portion548and bottom forming portion546of the recess forming portion, respectively.

The interface surface forming portions550are positioned a root (or bottom) radial distance556from the axis526at the bottom forming portion552of the interface surface forming portion550. The root radial556distance defines the recess forming portion inner radius556. The interface surface forming portion550is positioned a top forming portion radial distance559from the axis526at the top forming portion551of the interface surface forming portion550. The top forming portion radial distance559is larger than the recess forming portion inner radius (root or bottom radial distance)556. The ratio of the recess forming portion inner radius556to the nib outer radius557is from about 0.60 to about 0.65. In one example, the ratio of the recess forming portion inner radius556to the nib outer radius557is about 0.64 and in another example, the nib outer radius557is equal to 0.64.

The tapered interface surface forming portion550is concave to the axis526. However, the tapered interface surface forming portion550may also be flat. Tapered interface surface forming portions550may also be alternative shapes provided edge forming portions553,555are formed. In one particular concave configuration, the taper interface surface forming portion550has a radius of curvature equal to the radial distance from the axis26to the interface surface forming portion550. That is, the radius of curvature of the taper interface surface forming portion550decreases from the top forming portion551of interface forming portion550to the bottom forming portion552of interface forming portion550. In an alternative embodiment, the radius of curvature of the concave taper interface surface forming portion550is constant and equal to the top forming portion radial distance559. In another alternative embodiment, each portion of the concave interface surface forming portion550is positioned a radial distance greater than or equal to the radial distance from the axis26to the transition contour forming portion545at the interface surface edge forming portions553,555.

The interface surface forming portion550is tapered at an angle with respect to the axis26from about one half degree (0.5°) to about twelve degrees (12°). In one particular embodiment, the interface surface forming portion550is preferably tapered in at a taper angle554(FIG.3) from about four degrees (4°) to about eight degrees (8°), and more preferably about six degrees (6°).

FIGS.13-16show taper interface surface forming portions550formed between every pair of adjacent wing forming portion542. However, in some applications, it may be advantageous to construct the interference contours between only selected pairs, i.e., a subset, of transition contours with the understanding that some misalignment may commonly occur. This can be avoided to some extent, for example, in multi-lobed configurations, by constructing the interference contours symmetrically about the recess, such as between opposing pairs of wings, between diametrically opposed pairs of wings, between every other pair of wings, or in triangular configurations.

A threaded fastener is formed having a driver-engageable recess, like that of recess40(FIGS.1-3), i.e., that mate with the corresponding standard six lobed drivers as discussed above, by mechanically forming the head and recess. The head22may be formed in a conventional two-blow header machine in which the end of the wire or other material from which the fastener is made is supported in a die of the header machine and its head end is impacted, first with a punch that partially forms the head, and then with a finishing punch, like those described with reference toFIGS.12-15, that finishes the head and forms the driver-engageable recess. The general manufacturing of fasteners is well known and will not be described further in this application. An assortment of such well known methods can be used to construct the subject.

The above description and drawings are only to be considered illustrative of specific embodiments, which achieve the features and advantages described herein. Modifications and substitutions for specific conditions and materials and otherwise can be made. Fasteners are constructed in many different configurations and the application of the subject matter of this application is not intended to be limited to any particular type. For example, the recess40of the embodiment ofFIGS.1-3is hexalobular. However the principles of the disclosure may be applied to recess systems with three, four, five, eight or other number of wings and lobes. As another example, the embodiments described above are illustrated as the common form of fastener system involving a female recess on the fastener and a male configured driver. The interference contours of the subject fastener system, however, can be applied as well to the opposite arrangement (not shown) with a female recess (socket) on the driver and a male configured fastener. For another example, some fasteners do not have heads that clamp the work piece to the substrate. They may use a second threaded section to engage the work piece, instead. Whereas certain fasteners have clamping heads, the advantages provided by the configurations illustrated may be obtained in other fastener types such as non-clamping fasteners and others. Accordingly, the inventions are not considered as being limited by the foregoing description and drawings, but are intended to embrace all such alternatives, modifications, substitutes and variances.