A BLANK FOR MAKING FOOTWEAR INSERTS HAVING A FOOT-FITTED SHAPE

Abstract: The invention relates to a blank for making footwear inserts having a foot-fitted shape, including two sheets (1, 2) workable by heat treatment, of which a first, larger sheet (1) consists of a comparatively porous and soft, although plastically formable material, and a second, smaller sheet (2) serving as heel part consists of likewise plastically formable material, which has larger density and stiffness than the first-mentioned material. The second sheet (2) is embedded in the first sheet (1), which in turn surrounds the second sheet all-around inasmuch as the same has not only an upper layer (5) on the top side of the second sheet (2) and a lower layer (4) on the bottom side of the second sheet (2), but also peripheral portions (3), which extend outside the contour edge of the second sheet and of which a front portion is considerably larger than other portions. The blank is reversedly identical and therefore usable for forming of right shoe inserts as well as left shoe inserts.

Description: A BLANK FOR MAKING FOOTWEAR INSERTS HAVING A FOOT-FITTED SHAPE Technical Field of the Invention This invention relates to a blank for making footwear inserts having a foot-fitted shape, including two sheet workable by heat treatment, of which a first, larger sheet consists of a comparatively porous and soft, although plastically form- able material, and a second, smaller sheet serving as a heel part consists of a likewise plastically formable material, which has a larger density and stiffness than the material in the first sheet, the second sheet being embedded in the first sheet by being located between two part sheet having a roughly foot-like contour shape. Prior Art By EP 0147024, a method for the manufacture of shoe inserts is previously known in which a comparatively short heel part preformed to a cup-shape is press-formed together with a laminated sole part, which is built up by a lower base layer, a porous layer positioned on the top thereof, as well as an upper fabric layer, and which has a shape and a size corresponding to the shape and the size of the sole in the shoe in which the insert is intended to be applied. A disadvantage of this insert is that the same is adjusted to the shape and the size of the shoe, but not to the individual shape of the feet of the individual user, in that the two main components of the insert are press-formed between a pad and a die which always give one and the same standard shape of the finished insert. Another disadvantage is that each press mold can only provide inserts for one single type of shoes, e.g. right shoes, while inserts for the requisite second type, e.g. left shoes, have to be manufac ¬ tured in another press mold. Objects and Features of the Invention The present invention aims at obviating the above- mentioned disadvantages of the previously known footwear insert and at providing conditions for a simple, quick and efficient manufacture of footwear inserts, the shape of which may be adjusted individually to the shape of individual users' dif- ferent feet. Therefore, a primary object of the invention is to provide a blank, which by heat treatment may quickly be formed in such a way, that the shape of the insert is exactly adjusted to the individual shape of a foot. An additional object is to provide an insert blank that may be used for making right inserts as well as left inserts. Yet an object of the invention is to provide a blank which enables the making of inserts for different shoe and foot sizes, respectively. In other words, one and the same blank should be suitable to be used for the manufacture of differently large inserts fitting right feet as well as left feet. According to the invention, at least the primary object is attained by the features defined in the characterizing clause of claim 1. Preferred embodiments of the insert blank according to the invention are furthermore defined in the dependent claims. Further Elucidation of the Prior Art In SE 7812897-2 (publ. no. 438 245), a blank for mak- ing shoe inserts is described consisting of a single layer of a porous material, e.g. a foamed copolymer of ethylene polyvinyl acetate and polyethylene, which is press-formed while providing a heel-supporting insert. Also in this case, the press-forming is carried out during adaptation of the shape of the insert to only one certain given size of a right shoe or a left shoe. In EP 0159957 and SE 8002477-1 (publ. no. 417 666), respectively, shoe inserts are described, both of which are made by bringing a swellable material to expand during adoption of the shape of the insert to the shape of a foot. Thus, in these cases an individual adaptation of the shape of the insert to the foot is obtained per se, but these two manufacturing methods are complicated and expensive to carry out as a consequence of the fact that they require swelling of the insert- forming material . By CA 1320831 a shoe insert is previously known which is built up by four different layers, viz . a lower thermoplastic layer, a heel part sheet, a pad forming layer as well as an upper protection layer. Thus, this shoe insert is not rev- sersedly identical, which means that one and the same insert cannot be used both for right shoes and left shoes. Brief Description of the Appended Drawings In the drawings : Fig 1 is a perspective view of a plane blank according to the present invention, Fig 2 is a footwear insert formed by a heat-treated blank according to fig 1, Fig 3 is a side view of the insert according to fig 2, Fig 4 is a planar view from above of the blank according to fig 1, Fig 5 is an exploded cross-section in the direction perpendicularly to the length extension of the blank, show- ing the different layers of which the blank is built up, Fig 6 is an analogous cross-section showing the different layers according to fig 5 in a composed state, and Fig 7 is a cross-section through the finished insert in con- nection with a schematically shown foot. Detailed Description of a Preferred Embodiment of the Invention The initially plane blank according to the invention shown in figs 1, 4, 5 and 6, is composed of two sheet 1, 2, which are workable by heat treatment. Of these, a first, larger sheet 1 consists of a comparatively porous and soft, although plastically formable material, while the second, smaller sheet 2 consists of a material which has a larger density and stiff ¬ ness than the material in the sheet 1. Also the second sheet 2, which serves as a heel part in the finished insert, is plasti ¬ cally formable. As is best seen in fig 6, the second sheet 2 is embedded in the first sheet 1, the first sheet surrounding the second sheet all-around inasmuch as the same has not only an upper layer 5 on the top side of the sheet 2, but also a lower layer 4 on the bottom side of the sheet 2, the peripheral por ¬ tions 3, 3' extending outside the contour edge of the second sheet 2. More precisely, a comparatively narrow, U-shaped edge portion 3 extends along the side edges and the back edge, respectively, of the sheet 2, and a considerably larger edge portion 3 ' extending in the forward direction from the front edge of the sheet 2. In practice, the first sheet 1 should have a thickness of 3-5 mm, suitably approx. 4 mm, and the second sheet 2 a thickness of 1-3 mm, suitably approx. 2 mm, the total thickness of the blank in the area of the sheet 2 serving as a heel part amounting to 4-8 mm, suitably approx. 6 mm. As may be clearly seen in fig 5, the first sheet 1 is composed of two layers or part sheet 4, 5 formed with an identical, roughly foot-like contour shape, and which are equally thick. The insides 6 of these part sheet are in a suitable way, e.g. by agglutination or welding, permanently united to the opposite sides of the second sheet 2, as well as to each other, viz . along the edge portions 3, 3' that extend outside the sheet 2. Although it is feasible to use different porous plastic materials in the part sheet 4, 5, in practice ethyl polyvinyl acetate .of the type that has an initial density within the range of 35-45 kg/m 3 , e.g. 38 kg/m 3 is preferred. This material is not only light and elastic but also plastically formable by heat treatment at od- erate temperatures (in the range of 110-130 °C) . In the preferred embodiment shown in the drawings, also the second sheet 2 is composed of two thin, laminated layers or part sheet 7 having one and the same thickness, e.g. 1 mm. Lamination of the layers 7 may take place by welding or agglutination. The material in the layers 7 consists most suitable of a thermoplastic polyester having a density within the range of 1 200-1 300 kg/m 3 . Thus, in connection with the development of the invention a polyester material of the type that is commercially available under the trademark VERALITE® having a density of 1 290 kg/m 3 has been used with success. The contour shape of the first, porous sheet 1 resembles at least roughly the contour shape of the footwear for which the described blank is intended to be used. However, the sheet is larger than the shoe in question not only so far that the sheet is longer than the shoe, but also wider than the same is. In practice, the blank is intended to be used for a plurality of different shoe sizes within a given size interval, the sheet 1 being dimensioned somewhat larger than the largest shoe size within the interval in question, and considerably larger than the smallest shoe size within the same size interval. Also the second sheet 2 serving as heel part is at least somewhat larger than the largest intended shoe size in the sense that the same is wider than the shoe in question. On the other hand, the sheet 2 is considerably shorter than also the smallest shoe within the shoe size interval in question. In practice, the length of the sheet 2 should be within the range of 55-70% of the length of the sheet 1. In this way, the stiff sheet 2 will extend not only along the foot's heel but also along the larger part of its arch. In other words, the front edge portion of the sheet 2 will be located immediately behind the foot's front tread part. Load tests on which the present invention is based have shown that the laminated sheet 2 built up by at least two thin layers or part sheet is considerably stronger and more resistant to dynamic long-term load than a simple sheet of the same material. Although it is feasible, per se, to make the sheet 2 of one single, solid material layer, the shown, laminated sheet construction is, therefore, preferred in practice. The manufacture of a usable insert according to 2, 3 and 7 is carried out in the following way. The described, plane insert blank is heated to a suitable temperature (110-130 °C), e.g. in a hot blast furnace, and then the same is applied on top of a soft pad of a suitable material, such as conventional foam rubber. Suitably, this pad has a wedge-shaped form tapering in the forward direction, the front part of the blank abut ¬ ting against a front, leaning surface of the pad at the same as time the rear part is located in the area of an upper, horizontal surface of the pad. When a foot (which advantageously is covered with a heat-insulating sock) of the user/customer in question then is applied on top of the blank, the same will sink down into the pad, the shape of the still warm blank being adjusted to the individual shape of the foot in question. In the area of the transition between the horizontal top side of the pad and the surface leaning forwards, the impact of the blank against the bottom side of the foot will be particularly powerful, whereby the edge portion designated 8 in fig 3 on the external sheet 1 as well as the sheet 2 embedded therein, will distinctly be pressed in against the arch of the foot. When the material in the sheet 1 initially has a density of 38 kg/m 3 , the density will increase at heating to, e.g. 55 kg/m 3 , during proportional reduction of the thickness of the two layers 4, 5. In the finished insert, the stiff sheet 2 will form a steady support for the arch of the foot. When the stiff inner sheet 2 as well as the external sheet 1 after a certain time have been shaped according to the anatomic shape of the foot, the foot is taken away, and then redundant edge portions on the outer sheet 1 are cut away. After this, the inβert is ready to be used, i . e . be put into the shoe in question. Thanks to the fact that the blank according to the invention may be formed to a foot-adapted insert by a simple heat operation in combination with the foot in question being pressed down on a blank applied on a pad, inserts may be made in an extraordinary simple and commercially interesting way. Thus, individually shaped inserts may be prepared not only within prevalent orthopaedics activities, but also in any shoe sales shops. When a buyer has decided to buy a pair of shoes, suitable inserts may fast and easily be prepared by means of a few stock-kept blanks of standard size. Thus, so few as two or possibly three different standard sizes of blanks can, in practice, cover all different shoe sizes from, for instance, size 35 to size 46. In the finished insert, the stiff sheet 2 serves as a robust support for the rear part of the foot. In particular, the arch of the foot gets a distinct support by means of the edge portion 8. At the same time, the upper, porous part sheet 5 on top of the sheet 2 gives a pleasant softness, the lower, likewise porous and soft part sheet 4 smoothing minor irregu- larities in the sole part of the shoe, and the part sheet 4 and 5 together forming an elastic compressible material during use which effectively absorbs occurring impact motions during walk and running. Another advantage of the blank according to the invention in the preferred, described embodiment thereof, is that the same may be used for making right inserts as well as left inserts. Because the two part sheet 4 and 5 are equally thick and have an invertedly identical shape, any side of one and the same blank can be turned upwards during the forming of the finished insert. In the example, the part sheet 5 is shown turned upwards so as to enable the making of a right insert. If instead the part sheet 4 is turned upwards, the blank can be used for the manufacture of a left insert without the properties and advantages of the insert being altered.

Claims: Claims 1. Blank for making footwear inserts having a foot-fitted shape, including two sheet (1, 2) workable by heat treatment, of which a first, larger sheet (1) consists of a comparatively porous and soft, although plastically formable material, and a second, smaller sheet (2) serving as heel part consists of a likewise plastically formable material, which has a larger density and stiffness than the material in the first sheet, the second sheet (2) being embedded in the first sheet (1) by being located between two part sheet (4, 5) having a roughly footlike contour shape, c h a r a c t e r ! z e d in that the two part sheet (4, 5) surround the second sheet all-around by having peripheral portions (3, 3') which extend outside the contour edge of the second sheet (2), and that the two part sheet (4, 5) are equally thick, have an identical contour shape, consist of the same material, as well as are, with the insides (6) thereof turned against each other, permanently united not only to the opposite outsides of the second sheet (2), but also with each other along the peripheral portions (3, 3') which extend outside the second sheet (2), the blank being by the ir or-inverted uniformity thereof, usable for forming right shoe inserts as well as left shoe inserts. 2. Blank according to claim 1, c h a r a c t e r i z e d in that the second sheet (2) is composed of at least * two thin, laminated part sheet (7) having the same thickness. 3. Blank according to any one of the preceding claims, c h a r a c t e r i z e d in that the material in the two part sheet (4, 5) of the first sheet (1) consists of ethyl vinyl acetate having an initial density within the range of 35-45 kg/m 3 , while the material in the second sheet (2) consists of thermoplastic polyester having a density within the range of 1 200 - 1 300 kg/m 3 .

Inventors: BALKEFORS TORSTEN, BALKEFORS, TORSTEN
Applicants: BALKEFORS SUPPORT AB, BALKEFORS TORSTEN, BALKEFORS, TORSTEN
Application year: 2001
Main classification: A43B17
IPC codes: A43B7, A43B17