Joint and Method of Joining

The present invention relates to a method of joining pins, rods, or column members to body members. More particularly, the present invention pertains to a method of joining pins, rods or column members to body members by affixing the ends of such column members in cavities formed in the body members. The method of the present invention is particularly well suited for constructing shoe supports of the type generally described in applicant's parent U.S. Pat. No. 4,085,525.

In the specification of U.S. Pat. No. 4,085,525, there is described a shoe support, such as a heel, which consists of a plurality of straight column members having their upper ends, either directly or through another upper support member, fixed to the shoe and their lower ends fixed to a lower, ground-contacting support member. In one of the embodiments described in that patent application, the column members are fixed to the shoe structure or to the lower support member, or to both, by means of a hardenable adhesive material such as an epoxy resin, the ends of the several column members being positioned in respective cavities which are filled with the adhesive material.

The present invention pertains to an improved method for fixing the ends of column members in support members and is particularly well suited for the making of shoe supports of the type shown in U.S. Pat. No. 4,085,525.

In a broad form of the invention as presently contemplated, the pin or column member is provided with an enlarged head and is fixed in a cavity by first placing into the cavity a quantity of hardenable adhesive material such that when the column member end portion is inserted into the cavity, the resulting displacement of a portion of the adhesive material causes the adhesive material substantially exactly to fill the cavity, inserting the column member end portion into the cavity, and allowing the adhesive material to harden. Two or more column members may be fixed within a single cavity if desired.

These and other aspects and advantages of the present invention are more apparent in the following detailed description and claims, particularly when considered in conjunction with the accompanying drawings in which like parts bear like reference numerals. In the drawings:

FIG. 1 is an enlarged, fragmentary cross-sectional view depicting the end portion of a column member fixed within a cavity in a body member in accordance with the present invention and is taken generally along line 1--1 of FIG. 2;

FIG. 2 is an elevational view of a shoe structure including a shoe support formed in accordance with the present invention;

FIG. 3 is a fragmentary cross-sectional view similar to FIG. 1 but depicting a joint including a plurality of column members fixed within a single cavity; and

FIG. 4 is an elevational view similar to FIG. 2 but showing a shoe support including a joint of the type depicted in FIG. 3.

Body member 10, depicted in FIG. 1, can be formed, for example, by injection molding of a suitable material such as nylon, and is provided with a cavity 11 having substantially parallel side walls 12 and a substantially conical bottom wall 13. Preferably body member 10 is molded with cavity 11 formed therein, but if desired, the cavity can be formed into molded body member blanks.

Elongated column member 14, which, by way of example, can be formed of a high strength steel, is depicted in this embodiment as having a substantially circular cross-section. Column member 14 is provided with an enlarged head 15 which can be of a substantially spherical configuration. In a typical application, column member 14 may be of a diameter in the order of about 2 to 2.5 mm, with spherical head 15 having a diameter in the order of about 4 mm. Cavity 11 is somewhat larger in cross-section than head 15, for example being about one mm larger in diameter. As a consequence, before the adhesive material in cavity 11 has hardened, the position of column member 14 can be adjusted angularly with respect to body member 10. Shown in ghost outlines at 16 and 17 are extreme possible angular positions of the shank of the column member 14, thus illustrating the flexibility achievable by this method of fixing. Naturally, the greater the diameter of cavity 11, the greater the possible angularity of column member 14 in relation to the body member 10.

In the preferred practice of the present invention, prior to the insertion of head 15 into cavity 11, a quantity of hardenable adhesive material such as an epoxy resin adhesive is injected into the cavity. This quantity is precisely dispensed so that when head 15 is inserted into cavity 11 to the desired extent, e.g. until head 15 contacts bottom wall 13 as depicted in FIG. 1, with resulting displacement of a portion of the adhesive material by the head 15 and the adjacent end portion of the shank of the pin 14, cavity 11 is substantially exactly filled with the adhesive material. The quantity of adhesive material required can be readily determined from the geometries of the head portion 15, the adjacent end portion of column member 14, and cavity 11. This filling technique lends itself well to automatic operation and avoids any human contact with the hardenable adhesive material during the assembly of the shoe or other product. Head 15 and the adjacent end portion of column member 14 are then inserted to the desired extent into cavity 11 to displace a portion of the adhesive material. The angular position of column member 14 relative to body member 10 can be adjusted as desired prior to hardening of the adhesive material. The adhesive material is then allowed to harden. The joining operation can be performed with the aid of jigs which are pre-set to ensure the exact desired relationship between the members being joined. For example, when the present method is utilized in the assembly of shoes of the type shown in U.S. Pat. No. 4,085,525, the use of jigs to hold the various members ensures that the desired positional relationship is achieved between the heel plates and the foot of the heel, and the sole of the shoe. The jigs can be fitted to a curing machine to assure that the desired positions are maintained when the adhesive has hardened. The assembled unit is cured for a time suited for the adhesive material utilized for example a time in order of about one hour. This curing can be aided by heat, if appropriate, depending upon the particular adhesive material used. The jig is then available for another assembly operation or for the packing of the finished product.

It will be appreciated that since the end portion of column member 14 is plunged into the partially filled cavity 11, complete contact between the end portion of the column member and the adhesive material is achieved without cavitation, and it has been found that a joint of great strength is achieved in this manner. In order to destroy the joint, in fact, such force is required as to burst the material of the body member 10 or to break the column member 14.

FIG. 2 depicts a shoe structure 18 including a shoe support in the form of upper support member 10a, lower support member 10b, and column members 14. The end portions of the several column members 12 are rigidly fixed within respective cavities in upper support member 10a and lower support member 10b in accordance with the method of the present invention. The angular position of column members 14 relative to upper support member 10a can be adjusted to accommodate various heel heights.

With joints constructed in the manner described, and with the column members of the heel of a shoe such as depicted in FIG. 2 and disclosed in U.S. Pat. No. 4,085,525 forming a trapezoidal column structure, a heel structure is provided which combines great strength with sufficient flexibility to enable it to deal with lateral blows.

As depicted in FIG. 3, a plurality of column members, illustratively depicted in FIG. 3 as two column members 14a and 14b, can be fixed within a single cavity 11 of a body member 10 in accordance with the present invention. FIG. 4 illustrates a shoe structure 18a including a shoe support with joints having two column members 14a and 14b fixed within each cavity of upper support member 10c and lower support member 10d.

While the joint has been described above particularly in relation to the fixing of column members in the heel portion of a shoe, it will be appreciated that the same technique may be employed for the fixing of pins, rods, or column members in similar shoe supporting structures other than at the heel and in other diverse structures.

It will be appreciated that the invention is capable of embodiment in forms other than that specifically described above, and the present invention should not be regarded as restricted by the particularity of the preceding description.