CA1168440A - Process for producing improved insole for footwear - Google Patents
Process for producing improved insole for footwearInfo
- Publication number
- CA1168440A CA1168440A CA000394149A CA394149A CA1168440A CA 1168440 A CA1168440 A CA 1168440A CA 000394149 A CA000394149 A CA 000394149A CA 394149 A CA394149 A CA 394149A CA 1168440 A CA1168440 A CA 1168440A
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- insole
- blank
- insole blank
- shoe
- foot
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Abstract
TITLE: Process for Producing Improved Insole for Footwear.
ABSTRACT: A process for producing an insole for footwear in which an insole blank of suitable thermoplastic material is heated above its softening-point and then moulded in a shoe by the wearer's normal foot pressure. The insole blank provides a forefoot portion, a heel portion and an arch flare, is bevelled around the heel portion and the arch flare, and the forefoot portion tapers in thickness from the arch line forwards.
ABSTRACT: A process for producing an insole for footwear in which an insole blank of suitable thermoplastic material is heated above its softening-point and then moulded in a shoe by the wearer's normal foot pressure. The insole blank provides a forefoot portion, a heel portion and an arch flare, is bevelled around the heel portion and the arch flare, and the forefoot portion tapers in thickness from the arch line forwards.
Description
- 2 ~ ~6~4~
BACKGROUND OF THE INVENTION
FIE~D OF THE INVENTION
The present invention relates to a process for producing an insole for footwear.
The human foot is a biomechanically complex structure evolved over millenia to accommodate human beings walking in an upright posture on natural surfaces.
In general, natural surfaces are soft and yielding, and confo~m to the contours of the sole of the foot, providing uniform support for the foot in a biomechanically correct position. However, modern conditions require the foot to accommodate walking and running on hard, unyielding surfaces, with the mobility of the foot restricted by footwear. The foot has not yet evolved to accommodate these modern conditions, and as a result foot ailments ranging from fatigue, callouses, corns, and blisters to serious tendon damage, muscle strain and stress fractures are common. Overuse ailments due to poor biomechanical function are especially common among joggers, runners and athletes.
Insoles pre-formed to a supporting shape are well known (see for examples, U.S.Patents 32667~ and 3161970) but such mass-produced insoles are designed to suit only the 'average' foot and not to promote a scientifically .,"~ ,~
1~6~40 desirable relationship between the foot and leg of the individual wearer.
Ideally, an insole should be custom-built to fit a particular foot in a particular shoe, and should give to that foot a support which approximates to the support given by soft ground to the bare foot; i.e. uniform, stable, slightly resilient support over the whole of the lower surfaces of the foot. This type of support can be provided by a custom-made orthopaedic insole shaped to fit an individual foot by a doctor or podiatric specialist.
However, such custom-made insoles (called 'orthotics') are expensive and time-consuming to produce and require expert fitting.
Description of the Prior ~rt The prior art discloses a number of insoles designed to be 'customised' to an individual foot:-U.S.Patent No.3407406 discloses a shoe padfilled withmicrospheres which deforms to fit a foot; and U.S.Patents Nos.2794270 and 3903621 disclose a shoe lining containing a semi-liquid mouldable material. However, these devices cannot provide adequate support for a foot since they continue to change shape under the pressures exerted by the wearer's foot in use.
U.S.Patent 35~1412 discloses aboot liner into which a _ 4 _ ~ ~ 6 ~ ~0 liquid resin is injected and allowed to set while the wearerls foot is in position in the boot. This should, in theory, give ideal support, but in practice such a liner is restricting rather than supportive and fails to allow for normal flexing of the foot in use. Also, the set resin breaks down relatively rapidly in use.
U.S.Patent 396~577 discloses a casting unit in a shoe sole, the unit being filled with a mouldable material which is formed by a wearer's foot pressure and then cured to retain that shape permanently. However, the casting unit is bulky and requires a special shoe con-struction.
U.S.Patents 4237626, 36416~ and 3244177 all disclose partial or complete insoles which are designed to be custom-fitted by heating the insole, placing the wearer's foot in contact with the heated insole, and allowing the insole to cool and set to shape while being moulded by the wearer's foot pressure. However, although such insoles are comfortable and reasonably supportive in use, it has been found that they do not provide the equivalent of a custom-made orthopaedic insole, because basically, all these insoles can do is take an impression of the wearer's foot, without offering correct biomechanical support for that foot.
- 5- ~L~68440 Brief Summar~ of the Invention An object of the present invention is the provision of an inexpensive easily-fitted customized insole which is comfortable and issupportive in terms of biomechanical principles:- it supports and acts on the undersurface of the foot to promote an anatomically desirable relationship between the various parts of the body in movement and at rest e.g. as when walking on a 'natural' surface in bare feet. To achieve this object, the present invention provides an insole blank comprising a sheet of thermo-plastic material, said material having a softening-point temperature above ambient temperature but at which the material safely may be brought into proximity to human skin, and said material having a thickness and a density such that it is mouldable by normal foot pressure at the softening-point temperature but not below the softening-point temperature; said insole blank having the general shape of a shoe last bottom and providing a forefoot portion, a heel portion and an arch flare: said forefoot portion tapering in thickness from a thickness equal to that of the heel portion along the arch line to a thickness of 12~-75~o of the thickness of the heel portion at the front edge of the forefoot portion; the edge of the insole blank being bevelled to an angle in the range 25 - 50 at least around the arch flare and the heel portion, such that the lower surface of the insole blank is smaller than the upper surface and said lower surface is approximately equal in size to the size of the last bottom shape of the wearer's shoe; and the arch flare corresponding in position to the medial arch of the foot and having a width at the widest point thereof of between 20~o-~O~o greater than the ~t bottom shape of the wearer's shoe.
Preferably part of said heel portion is thinned to provide a teardrop-shaped depression having its least thickness at a point corresponding to the centre of the wearer's heel and oriented with the rounded part thereof corres-ponding to the wearer's heel and the attenuated part thereof extending along the lateral side of the insole and terminating opposite the arch flare.
The invention further provides a process for forming an insole comprising the steps of:
(a) providing an insole blank as described above;
(b) heating said blank to or above the softening-point . temperature of said material;
(c) with the insole blank in place in the shoe in which it is to be worn, placing the wearer's foot in said shoe, such that the insole blank is sandwiched between the wearer's foot and the inside of the shoe;
(d) standing so that normal foot pressure is exerted on ~68~
the insole blank, thereby moulding the insole blank into the shape of a supportivë insole; and (e) allowing the moulded insole to cool to ambient temperature.
The insole of the present invention is designed to be used with any ordinary shoe or boot having a conventional upper, of the size normally worn by the wearer.
Brief Descri~tion of the Drawin~
By way of example only, a preferred embodiment of the present invention will be described in detail, with reference to the accompanying drawings, in which:-Figs. 1 & 2 are side and bottom plan views respec-tively of an insole blank in accordance with the present invention;
Fig.3 is a side view of the completed insole;
Figs. 4 ~ 5 are side views of the medial and lateral sides respectively of a skeletal foot in a shoe fitted with the insole of the present invention, with the side of the shoe broken away;
Figs. 6, 7 & ~ are sections on lines A, B & C
respectively of Figs. 4 & 5.
In Figures 4-~, the insole is shaded for clarity.
The skeletal structure depicted assumes that the foot and lower leg are in neutral position i.e. the optimal functional position.
D_tailed Descri~ion of the Preferred Embodiments An insole 2 in accordance with the present invention is formed from a sheet of any suitable material.
suitable material is a material which is thermoplastic, with a softening-point temperature above ambient tempera-ture but at which the material safely may be brought into contact with or proximlty to human skin and to which foot-wear materials may be heated without damage. Generally, a softening-point temperature in the range 50 -~0 C is satisfactory. The material must be of a density such that it is mouldable by normal foot pressure above the softening-point temperature, but remains stable and un-affected by normal foot pressure in use. The material must be durable:- the insole should have a service life of at least 6-12 months. 3elow the softening-point, the material must be resilient yet firm, and stable in shape, so that the insole is not significantly altered by the compressive forces exerted by the foot in use. Also, the material must be sufficiently inert and hypoallergenic to be useable for long per~ds in contact with or proximity to human skin without causing skin problems. The material may be solid sheet or open -or closed-cell foamed sheet, and may be continuous or perforated.
, , 9 ~ 44(~
One suitable material is medium-denisity closed-cell foamed polyethylene having Shore Hardness 35.
An insole blank 4 provides a heel portion 5, a fore-foot portion 6 and an arch flare 7 and is cut from a sheet of material which tapers in thickness from a thickness X
at the heel end of the blank to a thickness Y at the toe end of the blank. The taper is not uniform along the length of the blank:- the greater thickness X extends from the heel to the arch line g; from the arch line g to the toe, the thicknessgradually tapers to Y. The arch line g-is a known characteristic of the human foot and is the line connecting the apices of the medial and longi-tudinal arches of the foot. From a large number of measurements made on different human feet, it is known that the arch line is always inclined at an angle a in the range 55 - gO (more commonly 65 - 75) to the longitudinal line 9 of the foot which extends between the mid-points of the toe and of the heel.
The inclination of the line g means that the taper in the thickness of the insole begins closer to the heel on the lateral side 10 than on the medial side 11:-this corresponds to the relationship between the apices of the medial and lateral longitudinal arches of the foot.
t is necessary for the forefoot portion 6 of the ' - 10~
insole to be tapered in thickness, to provide correct support for the metatarsal bones of the foot along their entire length (see Figs. 4 & 5). The forefoot portion 6 provides cushioning for the metatarsal heads 12a-e (see Fig.~)and also assists in positioning the insole correctly in the shoe, and in preventing movement of the insole in the shoe when in use.
The thickness X is in the range ~ mm and the thickness Y is in the range 2-~ mm, Y being 12% - 75~o of the thickness X.
In plan, the insole blank 4 is of conventional last bottom shape, except for the arch flare 7 along the medial side 11 of the insole. The arch flare 7 is 20 - ~0~0 (preferably 50~o) wider than the last bottom shape width Z, so that when the insole blank 4 is formed to shape, the arch flare 7 is bent upwards to provide an arch-supporting portion, the edge 13 of which rests against the medial side of the shoe upper, rather than on the bottom of the shoe. Conventional arch supports generally are thickened portions of the insole which rest on the bottom of the shoe, and so provide a non-variable support which suits only one~eight of arch. In contrast, the arch flare 7 can be formed during fitting to the correct height and shape to support correctly any height of arch, and integrate the shoe upper, insole and sole into an efficient functional 1.~4~(~
supporting unit for the individual foot.
The rearfoot or heel portion 5 of the insole 4 includes a teardrop-shaped portion 14 which is of reduced thickness compared to the remainder of the heel portion 5. The thinnest part 15 of said portion 14 corresponds to the position of the centre of a wearer's heel, and is equal to, or 2-4 mm thicker than, the thickness y of the forefoot portion. From said thinnest part 15, the thickness of the portion 14 gradually increases, so that the edges of said portion 14 join smoothly with the remainder of the heel portion 5. The teardrop shape is positioned such that the attenuated portion 16 of said shape extends along the lateral side 10 of the insole and terminates opposite the arch flare 7.
The portion 14 may be formed by grinding and may be formed on either the upper or the lower surface of the insole. Preferably, however, said portion is formed on the lower surface of the insole, to allow the upper surface to present a completely smooth surface to a wearer's foot.
The outer periphery of the insole is bevelled to an angle b of 25 - 50, preferably 35 - 42 (see Figs.
1 & 2). The bevel 17 may extend around the whole perimeter of the insole, as shown, but must extend from the ball of the foot around the heel portion of the insole. The ., - 12 - 116844~
bevel 17 assists the correct forming and positioning of the arch flare 7 and also, when the insole is moulded to shape, causes the edge of the insole to wrap up around the side of the shoe.
In use, this wrap-up helps to position the foot and prevents it from sliding about.
The bevel'l7 also assists in the formation of a heel cup 19 from the teardrop-shaped portion 14 when the insole is shaped to the wearer. The heel cup 19 conforms to the shape of the wearer's he~l, without unduly flattening the fat pad of the heel, and allows the foot to lie correctly, with the lateral side of the foot slightly lower than the medial side and the heel located securely (see Figs. 6 &
7). The heel cup 19 also provides sufficient resilient material under the lateral border of the foot to allow efficient shock absorption as the foot strikes the ground~
Ideally, the heel cup 19 should provide a shape similar to that formed by the foot on a 'natural'walking surface such as soft earth.
The heel cup 19 may extend to the edge of the insole or a flat margin (not shown) of width O - g mm may lie between the heel cup 19 and the edge of the insole. The width of the margin depends upon the design of the shoe with which the insole is to be used.
The above-described insole blank is custom-fitted . .
- 13 ~ 4 ~
to a wearer's foot as follows:- the blank is heated to a temperature equal to or greater than the softening-point temperature, preferably with said blank in position in the wearer's shoeO However, the blank may be heated alone, and inserted in the wearer's shoe when at the desired temperature; in this case, it is advantageous to have a cardboard stiffener of the same shape as the bottom forefoot portion secured to the lower surface of the fore-foot portion, to make it easier to manoeuvre the floppy heated insole blank into the shoe.
Next, the wearer puts an the shoe or shoes in his ordinary shoe size (preferably, both insoles of a pair are fltted simul~neously) and stands evenly on both feet, with a stance such that the middle of each kneecap is aligned with the third and fourth toes of the corresponding foot.
To assist the wearer to achieve the correct stance, a fitting aid may be used, consisting of a horizontal base plate with a vertical rod secured at one end:- the wearer stands on the base plate with one end of the rod aligned between the third and fourth toes, and the other end of the rod touching the centre of the kneecap. In this stance, the shape of the insole guides the foot into the optimum position.
This stance is maintained for several minutes (e.g.
BACKGROUND OF THE INVENTION
FIE~D OF THE INVENTION
The present invention relates to a process for producing an insole for footwear.
The human foot is a biomechanically complex structure evolved over millenia to accommodate human beings walking in an upright posture on natural surfaces.
In general, natural surfaces are soft and yielding, and confo~m to the contours of the sole of the foot, providing uniform support for the foot in a biomechanically correct position. However, modern conditions require the foot to accommodate walking and running on hard, unyielding surfaces, with the mobility of the foot restricted by footwear. The foot has not yet evolved to accommodate these modern conditions, and as a result foot ailments ranging from fatigue, callouses, corns, and blisters to serious tendon damage, muscle strain and stress fractures are common. Overuse ailments due to poor biomechanical function are especially common among joggers, runners and athletes.
Insoles pre-formed to a supporting shape are well known (see for examples, U.S.Patents 32667~ and 3161970) but such mass-produced insoles are designed to suit only the 'average' foot and not to promote a scientifically .,"~ ,~
1~6~40 desirable relationship between the foot and leg of the individual wearer.
Ideally, an insole should be custom-built to fit a particular foot in a particular shoe, and should give to that foot a support which approximates to the support given by soft ground to the bare foot; i.e. uniform, stable, slightly resilient support over the whole of the lower surfaces of the foot. This type of support can be provided by a custom-made orthopaedic insole shaped to fit an individual foot by a doctor or podiatric specialist.
However, such custom-made insoles (called 'orthotics') are expensive and time-consuming to produce and require expert fitting.
Description of the Prior ~rt The prior art discloses a number of insoles designed to be 'customised' to an individual foot:-U.S.Patent No.3407406 discloses a shoe padfilled withmicrospheres which deforms to fit a foot; and U.S.Patents Nos.2794270 and 3903621 disclose a shoe lining containing a semi-liquid mouldable material. However, these devices cannot provide adequate support for a foot since they continue to change shape under the pressures exerted by the wearer's foot in use.
U.S.Patent 35~1412 discloses aboot liner into which a _ 4 _ ~ ~ 6 ~ ~0 liquid resin is injected and allowed to set while the wearerls foot is in position in the boot. This should, in theory, give ideal support, but in practice such a liner is restricting rather than supportive and fails to allow for normal flexing of the foot in use. Also, the set resin breaks down relatively rapidly in use.
U.S.Patent 396~577 discloses a casting unit in a shoe sole, the unit being filled with a mouldable material which is formed by a wearer's foot pressure and then cured to retain that shape permanently. However, the casting unit is bulky and requires a special shoe con-struction.
U.S.Patents 4237626, 36416~ and 3244177 all disclose partial or complete insoles which are designed to be custom-fitted by heating the insole, placing the wearer's foot in contact with the heated insole, and allowing the insole to cool and set to shape while being moulded by the wearer's foot pressure. However, although such insoles are comfortable and reasonably supportive in use, it has been found that they do not provide the equivalent of a custom-made orthopaedic insole, because basically, all these insoles can do is take an impression of the wearer's foot, without offering correct biomechanical support for that foot.
- 5- ~L~68440 Brief Summar~ of the Invention An object of the present invention is the provision of an inexpensive easily-fitted customized insole which is comfortable and issupportive in terms of biomechanical principles:- it supports and acts on the undersurface of the foot to promote an anatomically desirable relationship between the various parts of the body in movement and at rest e.g. as when walking on a 'natural' surface in bare feet. To achieve this object, the present invention provides an insole blank comprising a sheet of thermo-plastic material, said material having a softening-point temperature above ambient temperature but at which the material safely may be brought into proximity to human skin, and said material having a thickness and a density such that it is mouldable by normal foot pressure at the softening-point temperature but not below the softening-point temperature; said insole blank having the general shape of a shoe last bottom and providing a forefoot portion, a heel portion and an arch flare: said forefoot portion tapering in thickness from a thickness equal to that of the heel portion along the arch line to a thickness of 12~-75~o of the thickness of the heel portion at the front edge of the forefoot portion; the edge of the insole blank being bevelled to an angle in the range 25 - 50 at least around the arch flare and the heel portion, such that the lower surface of the insole blank is smaller than the upper surface and said lower surface is approximately equal in size to the size of the last bottom shape of the wearer's shoe; and the arch flare corresponding in position to the medial arch of the foot and having a width at the widest point thereof of between 20~o-~O~o greater than the ~t bottom shape of the wearer's shoe.
Preferably part of said heel portion is thinned to provide a teardrop-shaped depression having its least thickness at a point corresponding to the centre of the wearer's heel and oriented with the rounded part thereof corres-ponding to the wearer's heel and the attenuated part thereof extending along the lateral side of the insole and terminating opposite the arch flare.
The invention further provides a process for forming an insole comprising the steps of:
(a) providing an insole blank as described above;
(b) heating said blank to or above the softening-point . temperature of said material;
(c) with the insole blank in place in the shoe in which it is to be worn, placing the wearer's foot in said shoe, such that the insole blank is sandwiched between the wearer's foot and the inside of the shoe;
(d) standing so that normal foot pressure is exerted on ~68~
the insole blank, thereby moulding the insole blank into the shape of a supportivë insole; and (e) allowing the moulded insole to cool to ambient temperature.
The insole of the present invention is designed to be used with any ordinary shoe or boot having a conventional upper, of the size normally worn by the wearer.
Brief Descri~tion of the Drawin~
By way of example only, a preferred embodiment of the present invention will be described in detail, with reference to the accompanying drawings, in which:-Figs. 1 & 2 are side and bottom plan views respec-tively of an insole blank in accordance with the present invention;
Fig.3 is a side view of the completed insole;
Figs. 4 ~ 5 are side views of the medial and lateral sides respectively of a skeletal foot in a shoe fitted with the insole of the present invention, with the side of the shoe broken away;
Figs. 6, 7 & ~ are sections on lines A, B & C
respectively of Figs. 4 & 5.
In Figures 4-~, the insole is shaded for clarity.
The skeletal structure depicted assumes that the foot and lower leg are in neutral position i.e. the optimal functional position.
D_tailed Descri~ion of the Preferred Embodiments An insole 2 in accordance with the present invention is formed from a sheet of any suitable material.
suitable material is a material which is thermoplastic, with a softening-point temperature above ambient tempera-ture but at which the material safely may be brought into contact with or proximlty to human skin and to which foot-wear materials may be heated without damage. Generally, a softening-point temperature in the range 50 -~0 C is satisfactory. The material must be of a density such that it is mouldable by normal foot pressure above the softening-point temperature, but remains stable and un-affected by normal foot pressure in use. The material must be durable:- the insole should have a service life of at least 6-12 months. 3elow the softening-point, the material must be resilient yet firm, and stable in shape, so that the insole is not significantly altered by the compressive forces exerted by the foot in use. Also, the material must be sufficiently inert and hypoallergenic to be useable for long per~ds in contact with or proximity to human skin without causing skin problems. The material may be solid sheet or open -or closed-cell foamed sheet, and may be continuous or perforated.
, , 9 ~ 44(~
One suitable material is medium-denisity closed-cell foamed polyethylene having Shore Hardness 35.
An insole blank 4 provides a heel portion 5, a fore-foot portion 6 and an arch flare 7 and is cut from a sheet of material which tapers in thickness from a thickness X
at the heel end of the blank to a thickness Y at the toe end of the blank. The taper is not uniform along the length of the blank:- the greater thickness X extends from the heel to the arch line g; from the arch line g to the toe, the thicknessgradually tapers to Y. The arch line g-is a known characteristic of the human foot and is the line connecting the apices of the medial and longi-tudinal arches of the foot. From a large number of measurements made on different human feet, it is known that the arch line is always inclined at an angle a in the range 55 - gO (more commonly 65 - 75) to the longitudinal line 9 of the foot which extends between the mid-points of the toe and of the heel.
The inclination of the line g means that the taper in the thickness of the insole begins closer to the heel on the lateral side 10 than on the medial side 11:-this corresponds to the relationship between the apices of the medial and lateral longitudinal arches of the foot.
t is necessary for the forefoot portion 6 of the ' - 10~
insole to be tapered in thickness, to provide correct support for the metatarsal bones of the foot along their entire length (see Figs. 4 & 5). The forefoot portion 6 provides cushioning for the metatarsal heads 12a-e (see Fig.~)and also assists in positioning the insole correctly in the shoe, and in preventing movement of the insole in the shoe when in use.
The thickness X is in the range ~ mm and the thickness Y is in the range 2-~ mm, Y being 12% - 75~o of the thickness X.
In plan, the insole blank 4 is of conventional last bottom shape, except for the arch flare 7 along the medial side 11 of the insole. The arch flare 7 is 20 - ~0~0 (preferably 50~o) wider than the last bottom shape width Z, so that when the insole blank 4 is formed to shape, the arch flare 7 is bent upwards to provide an arch-supporting portion, the edge 13 of which rests against the medial side of the shoe upper, rather than on the bottom of the shoe. Conventional arch supports generally are thickened portions of the insole which rest on the bottom of the shoe, and so provide a non-variable support which suits only one~eight of arch. In contrast, the arch flare 7 can be formed during fitting to the correct height and shape to support correctly any height of arch, and integrate the shoe upper, insole and sole into an efficient functional 1.~4~(~
supporting unit for the individual foot.
The rearfoot or heel portion 5 of the insole 4 includes a teardrop-shaped portion 14 which is of reduced thickness compared to the remainder of the heel portion 5. The thinnest part 15 of said portion 14 corresponds to the position of the centre of a wearer's heel, and is equal to, or 2-4 mm thicker than, the thickness y of the forefoot portion. From said thinnest part 15, the thickness of the portion 14 gradually increases, so that the edges of said portion 14 join smoothly with the remainder of the heel portion 5. The teardrop shape is positioned such that the attenuated portion 16 of said shape extends along the lateral side 10 of the insole and terminates opposite the arch flare 7.
The portion 14 may be formed by grinding and may be formed on either the upper or the lower surface of the insole. Preferably, however, said portion is formed on the lower surface of the insole, to allow the upper surface to present a completely smooth surface to a wearer's foot.
The outer periphery of the insole is bevelled to an angle b of 25 - 50, preferably 35 - 42 (see Figs.
1 & 2). The bevel 17 may extend around the whole perimeter of the insole, as shown, but must extend from the ball of the foot around the heel portion of the insole. The ., - 12 - 116844~
bevel 17 assists the correct forming and positioning of the arch flare 7 and also, when the insole is moulded to shape, causes the edge of the insole to wrap up around the side of the shoe.
In use, this wrap-up helps to position the foot and prevents it from sliding about.
The bevel'l7 also assists in the formation of a heel cup 19 from the teardrop-shaped portion 14 when the insole is shaped to the wearer. The heel cup 19 conforms to the shape of the wearer's he~l, without unduly flattening the fat pad of the heel, and allows the foot to lie correctly, with the lateral side of the foot slightly lower than the medial side and the heel located securely (see Figs. 6 &
7). The heel cup 19 also provides sufficient resilient material under the lateral border of the foot to allow efficient shock absorption as the foot strikes the ground~
Ideally, the heel cup 19 should provide a shape similar to that formed by the foot on a 'natural'walking surface such as soft earth.
The heel cup 19 may extend to the edge of the insole or a flat margin (not shown) of width O - g mm may lie between the heel cup 19 and the edge of the insole. The width of the margin depends upon the design of the shoe with which the insole is to be used.
The above-described insole blank is custom-fitted . .
- 13 ~ 4 ~
to a wearer's foot as follows:- the blank is heated to a temperature equal to or greater than the softening-point temperature, preferably with said blank in position in the wearer's shoeO However, the blank may be heated alone, and inserted in the wearer's shoe when at the desired temperature; in this case, it is advantageous to have a cardboard stiffener of the same shape as the bottom forefoot portion secured to the lower surface of the fore-foot portion, to make it easier to manoeuvre the floppy heated insole blank into the shoe.
Next, the wearer puts an the shoe or shoes in his ordinary shoe size (preferably, both insoles of a pair are fltted simul~neously) and stands evenly on both feet, with a stance such that the middle of each kneecap is aligned with the third and fourth toes of the corresponding foot.
To assist the wearer to achieve the correct stance, a fitting aid may be used, consisting of a horizontal base plate with a vertical rod secured at one end:- the wearer stands on the base plate with one end of the rod aligned between the third and fourth toes, and the other end of the rod touching the centre of the kneecap. In this stance, the shape of the insole guides the foot into the optimum position.
This stance is maintained for several minutes (e.g.
3-5 min) sufficiently to allow the insole material to cool 684~
enough to retain the desired shape. Preferably, the wearer then walks about for a further 2-3 minutes with his weight on his heels and on the outer sides of his feet.
Once the insoles have cooled9 they retain the shape to which they have been moulded by the wearer's foot pressure, and are permanently formed to that shape, unless re-heated above the softening-point. The finished insoles are firm, slightly resilient and flexible in the forefoot region, and constitute what is commonly known as a semi-rigid orthotic insole.
If the shoes are given to another wearer, or the existing wearer's feet change due to injury, ~he insoles can be remoulded to the desired new shape simply by repeating the heating and moulding steps described above.
Similarly, the insoles may be re-moulded to suit another pair of shoes.
The type of support required by a foot varys a great deal with the type of shoe worn~ and an insole made in accordance with the present invention is in general more satisfactory than known custom-made insoles, because the insole is moulded to the exact shape of the shoe in which it is to be worn, so that it supports the wearer's foot correctly in that particular shoe; i.e. the moulding process forms the insole to both the foot and the inner contours of the shoe in a functional position.
~6~3~4 _ 15 --If a wearer has particularly serious foot problems, the moulding process may be carried out under the super-visi~n of a medical practitioner or podiatric specialist.
The insert blank, with or without shoe, may be heated to the desired ternperature by any suitable means e.g. hot-air blowers or radiant or infra-red ovens. A
hot-air blower such as a commercial hair blow-dryer is especially useful for heating insoles in position in boots:-the blower simply is pointed down the boot~
The insole blank may have a heat-sensitive dye incorporated in it or applied to it:- the dye changes colour when the blank reaches the correct temperature.
For insoles made of medium-density closed cell polyethylene, with the thickest part of the heel portion 10 mm thick, the following heating programme gives satis-factory results:- the insoles are placed in the running shoes in which they are to be worn; a domestic oven is pre-heated to 100C and then turned off. The shoes containing the insoles are placed in the oven for 15 minutes, the ovem temperature being approximately 70¢.
The shoes are then removed and fitted to the wearer as described above.
To improve the eye-appeal of the insole blanks to customers, and to make the blanks easier to insert into the footwear, the blanks may be partly pre-forrned to i84~(~
shape by thermoforming techniques before being fitted to the wearer. However, this preforming does not alter the essential shape of the blank because the blank reverts to its original Iflat' shape as soon as it is heated above the softening-point prior to fitting.
The insole blanks may have a fabric liner laminated to the upper surface thereof. The for~ed lnsole can be removed from the shoe for washing if desired.
Figs.4-g show the way in which the insole of the present invention supports a wearer's foot in use:- the calcaneus 20 is held comfortably and securely in place by the heel cup 19, as described above the arch flare 7 supports the medial arch of the foot, with the bevelled edge 13 of the arch flare 7 resting against the side 24 of the shoe upper as shown in Fig.7. The bevel 17 causes the edge of the insole blank to wrap up against the inside edges 24 of the shoe as shown in Figs.6-~. This wrap-up supports the edges of the foot and helps to position and stabilize the foot correctly in the shoe, and also supports and stabilizes the lateral arch of the foot. The insole also cushions the whole sole of the foot.
.
enough to retain the desired shape. Preferably, the wearer then walks about for a further 2-3 minutes with his weight on his heels and on the outer sides of his feet.
Once the insoles have cooled9 they retain the shape to which they have been moulded by the wearer's foot pressure, and are permanently formed to that shape, unless re-heated above the softening-point. The finished insoles are firm, slightly resilient and flexible in the forefoot region, and constitute what is commonly known as a semi-rigid orthotic insole.
If the shoes are given to another wearer, or the existing wearer's feet change due to injury, ~he insoles can be remoulded to the desired new shape simply by repeating the heating and moulding steps described above.
Similarly, the insoles may be re-moulded to suit another pair of shoes.
The type of support required by a foot varys a great deal with the type of shoe worn~ and an insole made in accordance with the present invention is in general more satisfactory than known custom-made insoles, because the insole is moulded to the exact shape of the shoe in which it is to be worn, so that it supports the wearer's foot correctly in that particular shoe; i.e. the moulding process forms the insole to both the foot and the inner contours of the shoe in a functional position.
~6~3~4 _ 15 --If a wearer has particularly serious foot problems, the moulding process may be carried out under the super-visi~n of a medical practitioner or podiatric specialist.
The insert blank, with or without shoe, may be heated to the desired ternperature by any suitable means e.g. hot-air blowers or radiant or infra-red ovens. A
hot-air blower such as a commercial hair blow-dryer is especially useful for heating insoles in position in boots:-the blower simply is pointed down the boot~
The insole blank may have a heat-sensitive dye incorporated in it or applied to it:- the dye changes colour when the blank reaches the correct temperature.
For insoles made of medium-density closed cell polyethylene, with the thickest part of the heel portion 10 mm thick, the following heating programme gives satis-factory results:- the insoles are placed in the running shoes in which they are to be worn; a domestic oven is pre-heated to 100C and then turned off. The shoes containing the insoles are placed in the oven for 15 minutes, the ovem temperature being approximately 70¢.
The shoes are then removed and fitted to the wearer as described above.
To improve the eye-appeal of the insole blanks to customers, and to make the blanks easier to insert into the footwear, the blanks may be partly pre-forrned to i84~(~
shape by thermoforming techniques before being fitted to the wearer. However, this preforming does not alter the essential shape of the blank because the blank reverts to its original Iflat' shape as soon as it is heated above the softening-point prior to fitting.
The insole blanks may have a fabric liner laminated to the upper surface thereof. The for~ed lnsole can be removed from the shoe for washing if desired.
Figs.4-g show the way in which the insole of the present invention supports a wearer's foot in use:- the calcaneus 20 is held comfortably and securely in place by the heel cup 19, as described above the arch flare 7 supports the medial arch of the foot, with the bevelled edge 13 of the arch flare 7 resting against the side 24 of the shoe upper as shown in Fig.7. The bevel 17 causes the edge of the insole blank to wrap up against the inside edges 24 of the shoe as shown in Figs.6-~. This wrap-up supports the edges of the foot and helps to position and stabilize the foot correctly in the shoe, and also supports and stabilizes the lateral arch of the foot. The insole also cushions the whole sole of the foot.
.
Claims (16)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An insole blank comprising a sheet of thermo-plastic material, said material having a softening-point temperature above ambient temperature but at which the material safely may be brought into proximity to human skin, and said material having a thickness and a density such that it is mouldable by normal foot pressure at the softening-point temperature but not below the softening-point temperature; said insole blank having the general shape of a shoe last bottom and providing a forefoot portion, a heel portion and an arch flare: said forefoot portion tapering in thickness from a thickness equal to that of the heel portion along the arch line to a thick-ness of 12%-75% of the thickness of the heel portion at the front edge of the forefoot portion; the edge of the insole blank being bevelled to an angle in the range 25°-50° at least around the arch flare and the heel portion, such that the lower surface of the insole blank is smaller than the upper surface and said lower surface is approxi-mately equal in size to the size of the last bottom shape of the wearer's shoe; and the arch flare corresponding in position to the medial arch of the foot and having a width at the widest point thereof of between 20% - 80% greater than the last bottom shape of the wearer's shoe.
2. An insole blank as claimed in Claim 1 wherein part of said heel portion is thinned to provide a tear-drop shaped depression having its least thickness at a point corresponding to the centre of the wearer's heel and oriented with the rounded part thereof corresponding to the wearer's heel and the attenuated part thereof extending along the lateral side of the insole and terminating opposite the arch flare.
3. An insole blank as claimed in Claim 2 wherein said least thickness of said teardrop shaped depression is in the range t to (t + 3) mm where t is the thickness in millimetres of the front edge of the forefoot portion.
4. An insole blank as claimed in Claim 1 or Claim 2 wherein the bevel extends around the whole eddge of the insole blank.
5. An insole blank as claimed in Claim 1 or Claim 2 wherein the thickness of the heel portion is in the range 8-16 mm and the thickness of the forefoot portion is in the range 2-8 mm.
6. An insole blank as claimed in Claim 2 wherein said teardrop-shaped depression is formed on the lower surface of the insole blank.
7. An insole blank as claimed in Claim 1 or Claim 2 further comprising a former made of stiff material which is shaped to correspond to the forefoot portion and is secured thereto.
8. An insole blank as claimed in Claim 1 or Claim 2 further comprising a temperature-sensitive dye applied to or incorporated in the material of the blank, said dye being selected to change colour at the softening point of the material.
9. An insole blank as claimed in Claim 1 or Claim 2 wherein said material is a closed-cell foamed material.
10. A process for forming an insole comprising the steps of:-(a) providing an insole blank as claimed in Claim 1 or Claim 2;
(b) heating said blank to or above the softening-point temperature of said material.
(c) with the insole blank in place in the shoe in which it is to be worn, placing the wearer's foot in said shoe, such that the insole blank is sandwiched between the wearer's foot and the inside of the shoe;
(d) standing so that normal foot pressure is exerted on the insole blank, thereby moulding the insole blank into the shape of a supportive insole; and (e) allowing the moulded insole to cool to ambient temperature.
(b) heating said blank to or above the softening-point temperature of said material.
(c) with the insole blank in place in the shoe in which it is to be worn, placing the wearer's foot in said shoe, such that the insole blank is sandwiched between the wearer's foot and the inside of the shoe;
(d) standing so that normal foot pressure is exerted on the insole blank, thereby moulding the insole blank into the shape of a supportive insole; and (e) allowing the moulded insole to cool to ambient temperature.
11. The process as claimed in Claim 10 wherein the insole blank is placed in the shoe before carrying out step (b).
12. The process as claimed in Claim 10 wherein the insole blank is placed in the shoe after carrying out step (b).
13. The process as claimed in Claim 10 or Claim 11 wherein during step (d), the wearer stands with his third and fourth toes vertically aligned with the centre of his kneecap.
14. The process as claimed in Claim 10 or Claim 11 wherein step (b) is carried out by means of an electrically heated oven.
15. The process as claimed in Claim 10 or Claim 11 wherein step (b) is carried out by means of a hot-air blower.
16. The process as claimed in Claim 10 wherein between steps (a) and (b) the insole blank is partially pre-formed into the desired insole shape by thermoforming.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NZ19601081 | 1981-01-14 | ||
| NZ196010 | 1981-01-14 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1168440A true CA1168440A (en) | 1984-06-05 |
Family
ID=19919464
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000394149A Expired CA1168440A (en) | 1981-01-14 | 1982-01-14 | Process for producing improved insole for footwear |
Country Status (2)
| Country | Link |
|---|---|
| AU (1) | AU547066B2 (en) |
| CA (1) | CA1168440A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4669142A (en) * | 1985-11-27 | 1987-06-02 | Meyer Grant C | Method for making footwear insole |
| US4756096A (en) * | 1985-11-27 | 1988-07-12 | Meyer Grant C | Footwear insole |
| US4862605A (en) * | 1988-09-16 | 1989-09-05 | Gardner Harris L | Super sole inner-sole |
| US7549232B2 (en) | 2003-10-14 | 2009-06-23 | Amfit, Inc. | Method to capture and support a 3-D contour |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0820706A3 (en) * | 1989-11-17 | 1999-06-09 | Freehaven Investments Ltd | Improvements in or relating to orthotic devices |
| AUPO464497A0 (en) * | 1997-01-17 | 1997-02-13 | Cheong, Wilson | A fully adjustable arch support with a self-modification component and volume adjustability |
-
1982
- 1982-01-13 AU AU79483/82A patent/AU547066B2/en not_active Expired
- 1982-01-14 CA CA000394149A patent/CA1168440A/en not_active Expired
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4669142A (en) * | 1985-11-27 | 1987-06-02 | Meyer Grant C | Method for making footwear insole |
| US4756096A (en) * | 1985-11-27 | 1988-07-12 | Meyer Grant C | Footwear insole |
| US4862605A (en) * | 1988-09-16 | 1989-09-05 | Gardner Harris L | Super sole inner-sole |
| US7549232B2 (en) | 2003-10-14 | 2009-06-23 | Amfit, Inc. | Method to capture and support a 3-D contour |
Also Published As
| Publication number | Publication date |
|---|---|
| AU547066B2 (en) | 1985-10-03 |
| AU7948382A (en) | 1982-07-22 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |