NZ197233A - Plastics drive fastener polygonal shank with radially extending wings - Google Patents

Description

Priority Kt^.e(s): ..

Complete Specification Filed: Class: J.. T. PCblioation Date: 3.1.MAYJ985.

I» 0- Joums!, No: \2-71f..

I 28 MAY 1981 Patents Form No. 5 NEW ZEALAND PATENTS ACT 1953 COMPLETE SPECIFICATION "PLASTIC DRIVE FASTENER" -S/WE ILLINOIS TOOL WORKS INC. a corporation organized and existing under the laws of the State of Delaware, -U^.A. of &501 Wejs>4- Higgles C3ex>d, lUi'-.ois, faOOlIZ>,4=»o1 LX-~>i"Ve_ct £A-cd"<ae» op A»v\e^~ie^c\.. hereby declare the invention, for which -I/we pray that a patent may lt>e granted to me/us, and the method by which it is to be performed, to be particularly described in and by the following statement * 197233 BACKGROUND OF THE INVENTION: Plastic drive fasteners of various configurations are found in the art classified within the United States Patent Office as classes 24/73 and 85/5; more particularly particular reference should be made to the patent to Edwin Grant Swick, United States Letters Patent 3,810,279 issued May 14, 1974 and assigned to the canton assignee of the present invention. Such fasteners while suitable for many applications have a single inherent problen, namely, the insertion force for installing the fastener in an aperture or bore of a work piece is substantially equal to the force required for raroval of the fastener frcm such an aperture or bore. In sane applications it has been found desirable to provide a fastener which can be readily installed but which requires an excessive amount of force to remove same.

An object of the present invention is to provide a fastener requiring a greater force for its raroval frati an aperture than for its installation.

SUMMARY OF THE INVENTION: The present invention is an improvement over the teachings of United States Letters Patent 3,810,279 and provides a one piece plastics drive fastener including at least one head and a shank, said shank having a generally polygonal axially extending body portion providing a plurality of radially outwardly facing substantially flat surfaces, a plurality of integral resilient independent wings extending radially outwardly fran each of said surfaces at axially spaced intervals, each of said wings being bendable about a respective bend line during introduction of the fastener into a ccmplanentary apertured workpiece, certain wings extending from and I positioned in spaced relation along at least one of said surfaces being | angularly disposed so as to tilt in the direction of said head, and resisting means formed integrally with each of said certain wings to substantially increase the force required for raroval of said fastener frcm said aperture as compared to the force required to introduce said fastener into said aperture, each said resisting means comprising a thickened knuckled portion located at the juncture of the respective one of said certain wings and the respective one of said surfaces and operative so that the respective 187233 said bend line extends substantially parallel to and spaced radially outwardly frcm the respective one of said surfaces of said body portion.

Preferably the thickened knuckled portion is comprised by a thickened section located on the upper surface of the respective one of the certain wings .facing the head, the juncture of said thickened section with said upper surface forming said radially spaced bend line.

A further object of the present invention is to provide an economical fastener which can be readily molded in a two-plate mold.

Still another object of the present invention is to provide a fastener capable of being utilized with multiplicity of head styles as well as a plurality of differing designs of entry or nose configurations.

Other objects will be apparent to those skilled in the art when the specification is read in conjunction with the following drawings.

BRIEF DESCRIPTION OF THE DRAWINGS: Fig. 1 is an elevational view of one embodiment of the present invention ; Case 3623 1 Fig. 2 is a cross-sectional elevational view ti .:.i along line 2-2 of Fig. 1; Fig. 3 is an end view taken from the entering end of Fig. 2; V Fig. 4 is a fragmentary enlarged cross-sectional view of the improved wing portions of the present inventioh; Fig. 5 is an elevational view of a prior art drive fastener; Fig. 6 is a fragmentary view of a drive fastener having 10 angled wing elements without the improvement of the present invention; Fig. 7 is a fragmentary view of the present invention; Fig. 8 A is a schematic view of wing elements of the prior art; Fig. 8 B is an intermediate development of the type shown in Fig. 6; and Fig. 8 C is a schematic view of the present invention.

Detailed Description A plastic drive fastener of the improved variety contemplated by the present invention is generally designated by the 20 numeral 10 and includes a head (12) and a shank (14). While the present invention shows the head (12) as being a domed ceiling head, it should be recognized by those skilled in the art that this Case 3623 is merely one showing of a head form. Such a fastener, as contemplated by the present invention, can have a single head (12), as shown, or may include a multiplicity of axially spaced heads of the type normally used to fasten trim panels to automotive door interiors, not shown. ^ The importance of the present invention relates to a plastic drive fastener which can be readily installed into an apertured panel or a bore within a thick panel in which the removal force is far in excess of the force of installation. An em-bodiement of such a fastener is shown in Fig. 1 through 4, 7 and 8C. The shank (14) of such a fastener is generally non-circular or polygonal in configuration and provides a plurality of axially extending flat surfaces (16) which in the present embodiement are four in number, however, it should be appreciated that any equal number of flat surfaces will suffice. Extending outwardly from the flat surfaces (16) are a plurality of axially spaced flexible resilient wing elements (18) which are provided with a generally tapered undersurface (20) and a radially extending upper surface (22), as best seen in Fig. 2.

Along at least one flat surface (16) are a plurality of certain resilient wing elements (30) which are angularly disposed relative to the axis of the shank (14) and tilt upwardly, as viewed in the drawing, toward the head (12). The initial development work of this fastener was to utilize a tilted wing, as seen in Fig. 6, which had substantially the same configuration as the flexible wing elements (18) that extend radially outwardly. As Case 3623 1 can be seen in Fig. 6 these elements generally designated (32) flexed along a straight line formed by their juncture with the flat surface (16). The insertion and removal forces of such items were slightly different.

Further development resulted in the present embodie- ment shown in Fig. 1 through 4 and Fig. 7 wherein a knuckle portion (34) is added to each of the angled wing elements (30) this results in the certain wing elements (30) having a bend line (36), as best seen in Fig. 1, which is generally parallel to sur-10 face (16) but radially spaced outwardly therefrom in essence , this creates a short stubby wing element (30) that can be readily inserted into an aperture or bore but which resists with great tenacity the removal of the fastener from the aperture or bore. Tests were conducted on various configurations of wings and 15 the results of such tests are shown in pounds of force required to push the fastener in and to pull the fastener out. The figures are displayed in reference to the wing configurations shown in Fig. 8 A, 8 B and 8 C, the latter being the embodiement of the present invention. These test results are as follows: Fig. 8 A Fig. 8B Fig. 8C IN OUT IN OUT IN OUT 24 32 18.5 75 21 23 11. 5 14. 5 75 23 11 16. 5 70 19 22 . 5 13 80 24 21 . 5 82. 5 22 21 14. 5 65 22 23 . 5 12. 5 c*- co 22 12. 5 75 21 19 12 22. 5 75 18 12 27. 5 72. 5 CaS€t*3623. ' • • • •• • •• /EH AGES 21.5 22.2 14.1 23. 8 75.8 R EMO VAL / IIS^ER TION RATIOS 1.0 1.4 3.2 As will be noted there is a dramatic unexpected result in the device of the present invention as shown in Fig. 8C.

In the present disclosure the improved form of resilient wing (30) with its knuckle portion (34) is shown extending in opposite directions from two of the flat wall surfaces (16) of the shank (14) with the radially extending wing element (18) occupying the other two flat opposed surfaces. It will be recognized that the amount of force removal can be controlled for a fastener of this design dependent upon the number of surfaces provided with knuckled angled wing elements (30). Wing elements (30) extending from one or more of the surfaces is all that is required, however, all of the surfaces can utilize such a wing element. Where wing elements (30) or (18) are extending from only one or two surfaces, not shown, it has been found desirable to provide means, such as an axially extending centering rib, not shown, to locate the fastener for optimum operating conditions relative to the cooperating aperture or bore.

While the present shank (14) includes four flat surfaces (16) it should be appreciated that the wing element (18) and (30) can extend from and cover the entire width of the flat surface or alternatively the shank (14) can include, if desired, a plurality of axially extending recessess (40) which interrupt and space adjacent flat surfaces for purposes of accepting an axially extending tool.

It is also envisaged that the wing elements on at least one surface are axially offset from the wing elements on the other surfaces to thereby provide a . variety of grip lengths.

The nose portion (44) in the present embodiment is shown as an arrow-shaped member but it will be appreciated that other configurations are equally usable. The shank (16) can be blunk at the end, rounded, arrow-shaped, or pointed as may be desired.

RECEIVED 197233

Claims (2)

1. WHAT WE CLAIM IS; f 1. A one piece plastics drive fastener including at least one head and a shank, said shank having a generally polygonal axially extending body portion providing a plurality of radially outwardly facing substantially flat surfaces, a plurality of integral resilient independent wings extending radially outwardly from each of said surfaces at axially spaced intervals, each of said wings being bendable about a respective bend line during introduction of the fastener into a complementary apertured workpiece, certain wings extending from and positioned in spaced relation along at least one of said surfaces being angularly disposed so as to tilt in the direction of said head, and resisting means formed integrally with each of said certain wings to substantially increase the force required for removal of said fastener from said aperture as compared to the force required to introduce said fastener into said aperture, each said resisting means comprising a thickened knuckled portion located at the juncture of the respective one of said certain wings and the respective one of said surfaces and operative so that the respective said bend line extends substantially parallel to and spaced radially outwardly from the respective one of said surfaces of said body portion.
2. 2. A fastener of the type claimed in claim 1, wherein said thickened portion comprises a thickened section located on the upper surface of the respective one of said certain v?ings facing said head, the juncture of said thickened section with -■ said upper surface forming said radially spaced bend line. * ^ t ?,\ Sg \w\ A fastener of the type claimed in Claim 2, wherein * i V*" i:> said body portion is four sided in cross-section and said ij-s ! iv; .t certain angularly disposed knuckled wings are located along two opposed flat surfaces. - 9 - 19723 4. A fastener of the type claimed in Claim 2, wherein said fastener includes two heads maintained in spaced relation adjacent one end of said shank. 5. A fastener of the type claimed in Claim 2, wherein said fastener includes three heads maintained in spaced relation adjacent one end of said shank. 6. A fastener of the type claimed in Claim 2, wherein said surfaces are separated from the next adjacent surface by an axially extending recess. 7. A fastener of the type claimed in Claim 1, wherein the wing elements on at least one surface being axially offset from the wing elements on the other surfaces to thereby provide a variety of grip lengths. 8. A one piece plastics drive fastener substantially as herein described with reference to Figures 1 to Figure 4 and Figures 7 and 8C of the accompanying drawings. - 10 -