This application claims priority to and the benefit of, German patent application serial number 10352658.7, filed on Nov. 11, 2003, the entire disclosure of which is hereby incorporated herein by reference.
The present invention relates to sole elements for shoes and other articles of footwear and methods for their manufacture. The present invention relates in particular to sole elements for shoes having a specific density distribution in a transverse and/or longitudinal direction.
It is generally known that injuries may arise if the moving parts of the body are subjected to high stress during walking or running. Such injuries arise in particular with sports requiring a great amount of movement. This applies for both contact sports, for example soccer, and non-contact sports, for example running or jogging.
In particular, long distance runners are often concerned with injuries or stress on the moving parts of the body, which may reduce performance and may lead to the inability to further perform this sport. The most serious of these injuries are injuries to the knee or injuries to the cartilage. Such injuries arise often due to the turning movement that accompanies the gait cycle when the foot contacts the ground and pushes off from the ground. Two types of turning movements that are considered as being dangerous are pronation and supination. Both lead often to injuries of the knee. Pronation is a rotation or turning of the foot from a lateral side, i.e., the outer side, of the foot to a medial side, i.e., the inner side, of the foot. During the gait cycle, the foot typically contacts the ground at first with the outer part of the heel. The weight is then shifted to the forefoot part to start the pushing-off phase. During this pushing-off phase, the pronation turning to the medial side of the foot starts. Supination is a corresponding turning of the foot from the medial side to the lateral side of the foot. Both often lead to injuries of the knee.
To address the above-mentioned problems, several approaches have been suggested in the prior art. For example, U.S. Pat. No. 4,615,126, the disclosure of which is hereby incorporated herein by reference in its entirety, describes a sole unit, in particular for sports shoes, with segments in the forefoot part at the third to fifth metatarsal-phalangeal joints of the foot with an increased flexibility in comparison to the remaining part of the sole unit. Such a configuration may reduce the resistance of the sole unit with respect to the bending of the foot along the third to fifth metatarsal-phalangeal joints, whereby tensions in the respective muscles are reduced and a pushing-off movement in particular by the first and second metatarsal-phalangeal joints of the foot is achieved. The provision of the more flexible part in the forefoot part may lead to a reduction of the pronation or supination movement.
Another known solution, as shown for example in U.S. Pat. No. 5,025,573, the disclosure of which is hereby incorporated herein by reference in its entirety, relates to a sole unit with different parts made out of substances with different elastic properties. The described sole unit consists of two layers, i.e., a lower layer of a firm material (which may also serve as the outsole) and an upper softer layer. The lower layer has an increased thickness in the heel part and in the part of the arch that serves as an upper stabilizing surface for the foot. The superposed softer damping layer is formed complementary to the lower firmer layer and to the foot, where its thickness varies in dependence of the transverse position.
Yet another known solution is, for example, described in International Patent Application No. WO95/03719 filed under the PCT, the disclosure of which is hereby incorporated herein by reference in its entirety. According to this approach, pronation is counteracted by inserting into the heel part of the sole unit a wedge-like element being on its lower side in contact with the outsole. The wedge-like element comprises upper and lower layers of a composite material of carbon fibers with a springy core material in between. The wedge-like element tapers from the medial side to the lateral side and from the heel to the midfoot area. In other words, the wedge-like element tapers in two directions.
In addition, U.S. Pat. No. 4,642,911, the disclosure of which is hereby incorporated herein by reference in its entirety, discloses a sole construction that is to be further described with reference to
In the following, a manufacturing method for sole units according to the prior art is discussed, consisting of parts with different density. Reference is made thereto to
Subsequently, the sole unit is formed into its desired shape (
For at least these reasons, the complex forming of two materials to be interconnected for achieving a desired density variation is only possible with a high expenditure.
Thus, it is an object of the present invention to provide a sole unit for shoes, in particular for sport shoes, that can be produced in a simple and, therefore, convenient manner with respect to the production technology, and still allow a predetermined density variation in a transverse and/or longitudinal direction over a complete area of the sole element.
One aspect of one embodiment of the present invention is to not use two different materials with different densities to create the density variation over the sole element and to connect these materials subsequently, but to use a single material being supplied as a preform and having a thickness distribution that is transformed by pressure forming into the desired density distribution.
One advantage of this embodiment of the invention is that all subsequent problems of the interconnection of different sole elements are no longer present and the complete sole element is finished in a single production step. Since the resulting density variation is primarily correlated with the geometrical dimensions of the preform, any variation of the density and, therefore, of the elastic properties over the complete area of the sole unit can be achieved without the complementary formation of two material layers.
In one approach to an embodiment of the invention, a preform with a varying thickness in a transverse and/or longitudinal direction is not used for obtaining the density variation, but instead a homogeneous preform that is differently expanded in the forming tool by a selective supply of heat is used. The density distribution is, therefore, obtained by locally differently expanded parts of the polymer material.
In one aspect, an embodiment of the invention relates to a method of manufacturing a sole element for a shoe, where the sole element has a varying density distribution in at least one direction, for example a transverse and/or longitudinal direction. The method includes manufacturing a sole element preform from a polymer material with a thickness varying in the transverse and/or longitudinal direction depending on the specific density distribution desired and press-forming the sole element preform in a forming tool to form the finished sole element from the sole element preform. In one embodiment, the finished sole element has a substantially constant thickness in at least one transverse direction. Additionally, the sole element preform may be subjected to a non-uniform compression during the press-forming step.
In another aspect, an embodiment of the invention relates to a method of manufacturing a sole element for a shoe, where the sole element has a varying density distribution in at least one direction, for example a transverse and/or longitudinal direction. The method includes manufacturing a sole element preform from a polymer material and press-forming the sole element preform in a forming tool with a selective supply of heat to single sections of a surface of the tool to locally selectively expand the sole element preform to form the finished sole element with the desired density distribution from the sole element preform.
In another aspect, an embodiment of the invention relates to a sole element for a shoe. The sole element includes a homogeneous polymer material including a portion having a locally varying density. The homogeneous polymer material may include ethylene vinyl acetate. In addition, the sole element can include a border part having a homogeneous density disposed adjacent to the portion having a locally varying density.
In another aspect, an embodiment of the invention relates to a forming tool for the manufacture of a sole element for a shoe out of sole element preforms, wherein the forming tool includes heating elements that are locally associated to a forming surface of the tool for the selective supply of heat to single parts of the forming surface of the tool to expand selective parts of the sole element preform to form the sole element. The resulting sole element has a varying density distribution.
In various embodiments of the foregoing aspects, the method includes the step of supplying heat during the press-forming. Density can increase gradually from a lateral side of the sole element to a medial side of the sole element or density can decrease gradually from a lateral side of the sole element to a medial side of the sole element. Alternatively or additionally, density of the sole element can vary from a rear foot part of the sole element to a forefoot part of the sole element. In one embodiment, the step of manufacturing the sole element preform includes the step of manufacturing the preform with a thickness decreasing linearly or non-linearly from a medial side of the preform to a lateral side of the preform. Sole elements manufactured by such a method can be adapted to different sports and to the different anatomy of a respective wearer.
Furthermore, the step of manufacturing the sole element preform can include the step of manufacturing the preform with a first portion having a substantially constant thickness from a medial side of the preform, an intermediate portion with a linear decrease in thickness, and a second portion having a substantially constant thickness in a direction of a lateral side of the preform. In one embodiment, the step of manufacturing the sole element preform can include the step of providing a preform including a rim of substantially constant thickness.
Additionally, the step of manufacturing the sole element preform can include the steps of expanding a block, for example a quadrant-shaped block, of a polymer material and subsequently cutting the expanded block into pieces with the respective desired varying thickness, thereby obtaining the specific thickness distribution. The cut preforms with varying thickness can then be formed into the sole element. In one embodiment, the preform is not produced at first as a quadrant-shaped block, but directly with the corresponding thickness modulation. This can, for example, be achieved by producing the preform by injection molding. In one embodiment, the polymer material can be ethylene vinyl acetate.
In additional embodiments, the step of manufacturing the sole element preform can include injection molding of the preform. In one embodiment, the sole element has a homogeneous polymer material including a portion having a locally varying density. The homogeneous polymer material can include ethylene vinyl acetate. The sole element can include a border part having a homogeneous density disposed adjacent to the portion having a locally varying density. In one example, the sole unit has a border part with a substantially constant density in the lateral side part and the medial side part to provide additional support to the foot.
Additional embodiments include a sole element manufactured in accordance with the preceding methods and a sole for an article of footwear that includes a sole element manufactured in accordance with the preceding methods. In one embodiment, the invention relates to an article of footwear including an upper and a sole including a sole element manufactured in accordance with the preceding methods.
These and other objects, along with advantages and features of the present invention herein disclosed, will become apparent through reference to the following description, the accompanying drawings, and the claims. Furthermore, it is to be understood that the features of the various embodiments described herein are not mutually exclusive and can exist in various combinations and permutations.
In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention. In the following description, various embodiments of the present invention are described with reference to the following drawings, in which:
In the following description, various embodiments of the methods in accordance with the invention relate to a sole element. It should, however, be noted that a sole element in accordance with the invention is typically used as part of a sole ensemble. That is, the sole element in accordance with the invention is typically formed as a midsole, where an outsole and an insole for improving comfort are additionally provided. Furthermore, it is not necessary that the sole element extends in a longitudinal direction (i.e. from the heel to the forefoot part) over the complete sole. It is also possible that a sole element in accordance with the invention is only used in the heel and/or in parts of the forefoot.
In the following, the human anatomy of the foot is discussed with reference to
It is an object of the present invention to compensate for the above-described pronation movement and the more rarely arising supination movement by providing the parts of the sole that are below the parts of the foot “being in the air” with an increased density and thereby with a reduced elasticity.
It is known to manufacture soles or parts of soles from expanded polymers, for example, polyurethane (PU) foams. To this end, the polymer material to be expanded is at first expanded into blocks that are subsequently cut into single preforms (so-called blockers). These blockers are inserted into a forming tool and subsequently formed into the desired shape of the sole element with the application of pressure and heat. A sole element produced in such a way can either have a constant thickness over the area of the foot or, if needed, also be formed with a foot-bed. It was, however, a common feature of the preforms known in the prior art to have either a constant thickness (if the sole element to be produced had a constant thickness) or a variation of the thickness corresponding to the variation of the thickness of the sole to be produced. In contrast, the present invention is based, in one example, on a first embodiment of preforms having a thickness modulation in a transverse and/or longitudinal direction corresponding to the density distribution that is later to be obtained.
One embodiment of a preform 20 in accordance with the invention is shown in
The corresponding dimensions can be taken from the following table, where the substantially constant hardness of the preform is about 40 C (Shore C):
It can be derived from the table that the preform 20 has at its left side 13 a height (or thickness) of about 25 mm. This corresponds to about 192% of the thickness of the end-formed sole element 25 (see below). At the outermost right side 15 the preform 20 has a thickness of about 15 mm, which corresponds to about 115% of the final thickness of the sole element. Generally, in one embodiment, the change in height or thickness (Δh=horiginal−hfinal) of the preform 20 after forming represents a non-uniform compression of the preform 20. For example, there is greater compression on the left side 13 vs. the right side 15. Further, the ratio of final height to original height (hfinal/horiginal) will be non-constant and can vary. In the example referenced in Table 1, this ratio ranges from about 50% to about 90%. Values outside this range are also within the scope of the invention.
If such a preform 20 is formed in a conventionally known forming tool, the sole element 25, as shown in
As depicted in
If the hardness of the resulting sole element 25 is measured with reference to the distance from the left side 13′, the following values shown in Table 2 are obtained:
As can be seen, the hardness (measured in Shore C) decreases from about 60 C to about 50 C. Therefore, a reduction of about 10 C is obtained (i.e., in the range of about 15% to 20%), if the preform 20 is as described in Table 1 and consists of polyurethane. Values outside this range are also within the scope of the invention. It should be noted that the dimensions given herein are exemplary only, and that the specific size, shape, and hardness of the preforms 20 and/or the resultant sole elements 25 will vary to suit the particular application. For purposes of explanation, the preforms 20 shown in
The locally varying hardness of the sole unit 25 can be explained by the surplus of material on the left side 13, which is compressed more than the material on the right side 15 during the final forming step in such a way that a continuously varying density distribution is obtained in the sole unit 25. The resulting density, in turn, influences the hardness and therefore the elasticity of the sole unit 25.
In the following, several alternative embodiments of preforms 20-1 to 20-4 are described with reference to the
The preform 20-1 shown in
The embodiment shown in
In particular, in the context of the preforms 20-3, 20-4 shown in
An additional method in accordance with the invention for the manufacture of sole elements with a desired density distribution is described with reference to
Having described certain embodiments of the invention, it will be apparent to those of ordinary skill in the art that other embodiments incorporating the concepts disclosed herein may be used without departing from the spirit and scope of the invention. The described embodiments are to be considered in all respects as only illustrative and not restrictive.
Number | Date | Country | Kind |
---|---|---|---|
103 52 658 | Nov 2003 | DE | national |
Number | Name | Date | Kind |
---|---|---|---|
2099418 | Bradley et al. | Nov 1937 | A |
2917842 | Scholl | Dec 1959 | A |
3418732 | Marshack | Dec 1968 | A |
3576911 | Maxey | Apr 1971 | A |
3591882 | Pearsall | Jul 1971 | A |
3738373 | Glancy | Jun 1973 | A |
3766669 | Pearsall | Oct 1973 | A |
4076876 | Bowles | Feb 1978 | A |
4216131 | Himes et al. | Aug 1980 | A |
4316335 | Giese et al. | Feb 1982 | A |
4372059 | Ambrose | Feb 1983 | A |
4378642 | Light et al. | Apr 1983 | A |
4418483 | Fujita et al. | Dec 1983 | A |
4476180 | Wnuk | Oct 1984 | A |
4615126 | Mathews | Oct 1986 | A |
4640797 | Goguen | Feb 1987 | A |
4642911 | Talarico, II | Feb 1987 | A |
4694589 | Sullivan et al. | Sep 1987 | A |
4747989 | Peterson | May 1988 | A |
4779359 | Famolare, Jr. | Oct 1988 | A |
4823483 | Chapnick | Apr 1989 | A |
4864739 | Maestri | Sep 1989 | A |
4910886 | Sullivan et al. | Mar 1990 | A |
4936030 | Rennex | Jun 1990 | A |
5025573 | Giese et al. | Jun 1991 | A |
5154682 | Kellerman | Oct 1992 | A |
5282328 | Peterson | Feb 1994 | A |
5551173 | Chambers | Sep 1996 | A |
5687441 | Rachman et al. | Nov 1997 | A |
5695850 | Crow | Dec 1997 | A |
5709954 | Lyden et al. | Jan 1998 | A |
5786057 | Lyden et al. | Jul 1998 | A |
5885500 | Tawney et al. | Mar 1999 | A |
6092314 | Rothbart | Jul 2000 | A |
6360453 | Ellis, III | Mar 2002 | B1 |
6528140 | Kalin et al. | Mar 2003 | B1 |
6725578 | Kerrigan | Apr 2004 | B2 |
7100308 | Aveni | Sep 2006 | B2 |
20020139011 | Kerrigan | Oct 2002 | A1 |
Number | Date | Country |
---|---|---|
1281506 | Feb 2003 | EP |
9-23904 | Jan 1997 | JP |
WO 9503719 | Feb 1995 | WO |
Number | Date | Country | |
---|---|---|---|
20050166423 A1 | Aug 2005 | US |