CA2078755A1 - Shoe lift construction - Google Patents
Shoe lift constructionInfo
- Publication number
- CA2078755A1 CA2078755A1 CA002078755A CA2078755A CA2078755A1 CA 2078755 A1 CA2078755 A1 CA 2078755A1 CA 002078755 A CA002078755 A CA 002078755A CA 2078755 A CA2078755 A CA 2078755A CA 2078755 A1 CA2078755 A1 CA 2078755A1
- Authority
- CA
- Canada
- Prior art keywords
- resin
- layer
- lift
- layers
- molded
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- A—HUMAN NECESSITIES
- A43—FOOTWEAR
- A43B—CHARACTERISTIC FEATURES OF FOOTWEAR; PARTS OF FOOTWEAR
- A43B21/00—Heels; Top-pieces or top-lifts
-
- A—HUMAN NECESSITIES
- A43—FOOTWEAR
- A43B—CHARACTERISTIC FEATURES OF FOOTWEAR; PARTS OF FOOTWEAR
- A43B21/00—Heels; Top-pieces or top-lifts
- A43B21/02—Heels; Top-pieces or top-lifts characterised by the material
- A43B21/06—Heels; Top-pieces or top-lifts characterised by the material rubber
- A43B21/08—Heels; Top-pieces or top-lifts characterised by the material rubber combined hard and soft rubber
-
- A—HUMAN NECESSITIES
- A43—FOOTWEAR
- A43B—CHARACTERISTIC FEATURES OF FOOTWEAR; PARTS OF FOOTWEAR
- A43B21/00—Heels; Top-pieces or top-lifts
- A43B21/36—Heels; Top-pieces or top-lifts characterised by their attachment; Securing devices for the attaching means
- A43B21/42—Heels with replaceable or adjustable parts, e.g. top lift
Landscapes
- Footwear And Its Accessory, Manufacturing Method And Apparatuses (AREA)
- Injection Moulding Of Plastics Or The Like (AREA)
Abstract
Abstract of the Disclosure This disclosure comprises a replaceable lift 3 for attachment to the heel of a shoe. The lift is molded from two resin layers, an upper layer and lower layer, and one of these two resin layers is preferably molded from a hard resin, and the other layer is pref-erably molded from a hard resin, and the other layer is preferably molded from a relatively soft resin. Fur-thermore, connecting holes are formed in one of the layers and connecting projections are formed in the other layer in order to form the upper and lower resin layers into a single piece. For example, a nylon resin layer is used for the upper layer and a urethane resin layer is used for the lower layer.
Description
~a7~5 Field of the Invention This invention relates to a lift or sole con-struction for a shoe, in which the lift attached to the bottom of the heel of either a man's shoe or woman's shoe is molded into a single piece from two resin layers and which displays excellent advantages with regard to both health and wearing comfort.
Background of the Invention Accompanying the trends of recent years toward more diversified consumer needs and greater health awareness, there have also been changes made in the constructions used Eor shoe heels. The lifts or soles attached to the bottom oE shoe heels have alway~
been easily ~ubject to wear, and the replaceability of those lifts has been an important problem. Iron ring lifts, hard rubber, and other constructions were origi-nally used for the lifts on women's shoes, but there were problems with such matters as wear resistance, and recently the most common material used for lifts has come to be urethane resin, which features excellent wear re~istance. However, the change to this material did not eliminate the need for replaceability. Espe-cially on high-heeled shoes, the largest proportion of the weight of the wearer is exerted upon the lifts attached to the bottom of the heel, and because of the small surface area, these lifts are subject to severe wear and thus require replacement frequently. In the -~. . ' . ~ .
past, because it has been difficult to replace li ~ ~7 8 other than at a shop ~pecializing in shoe repair, the result was a shortening of the life of the product.
For this reason, heel device~ have been proposed for which it is possible for the lift to be replaced rela-~ively easil~ without requiring any special skill, such as that described in laid open in Japanese Utili~y Model Publication Sho. 63-4407.
Incidentally, even if the lifts of the prior art differ as to whether or not replacement is easy, the entire lift is still molded into a solid piece from urethane re~in or a similar substance.
The following problems occ~lrred as a result of the lifts of the prior art being molded into a solid piece from a ~ingle layer of resin:
(1) If the lift was molded into a solid piece from hard urethane resin, the impact shock -from walking on a hard floor surface would reverberate to the head of the wearer, thus ~0 presenting problems with regard to both health and wearing comfort.
Background of the Invention Accompanying the trends of recent years toward more diversified consumer needs and greater health awareness, there have also been changes made in the constructions used Eor shoe heels. The lifts or soles attached to the bottom oE shoe heels have alway~
been easily ~ubject to wear, and the replaceability of those lifts has been an important problem. Iron ring lifts, hard rubber, and other constructions were origi-nally used for the lifts on women's shoes, but there were problems with such matters as wear resistance, and recently the most common material used for lifts has come to be urethane resin, which features excellent wear re~istance. However, the change to this material did not eliminate the need for replaceability. Espe-cially on high-heeled shoes, the largest proportion of the weight of the wearer is exerted upon the lifts attached to the bottom of the heel, and because of the small surface area, these lifts are subject to severe wear and thus require replacement frequently. In the -~. . ' . ~ .
past, because it has been difficult to replace li ~ ~7 8 other than at a shop ~pecializing in shoe repair, the result was a shortening of the life of the product.
For this reason, heel device~ have been proposed for which it is possible for the lift to be replaced rela-~ively easil~ without requiring any special skill, such as that described in laid open in Japanese Utili~y Model Publication Sho. 63-4407.
Incidentally, even if the lifts of the prior art differ as to whether or not replacement is easy, the entire lift is still molded into a solid piece from urethane re~in or a similar substance.
The following problems occ~lrred as a result of the lifts of the prior art being molded into a solid piece from a ~ingle layer of resin:
(1) If the lift was molded into a solid piece from hard urethane resin, the impact shock -from walking on a hard floor surface would reverberate to the head of the wearer, thus ~0 presenting problems with regard to both health and wearing comfort.
(2) In addition, the lifts were often colored black (colored with carbon black) in order to present a slim appearance from a design as-pect, and this could result in marks being made on the floor surface while walking.
(3) Further~ore, If the entire lift was mol~e~ 7 into a solid piece from soft resin in consid-eration of the health aspect, the manner in which the weight of the wearer was applied while walking could cause the lift to tilt sideways, thus presenting the danger of the wearer twisting an ankle.
In consideration of the factors described above, it is a general object of this i.nvention is to provide a lift construction which increases the product value of the shoe, by molding a replaceable lift into a single piece from two resin layers, upper and lower, and, moreover, by selecting resins having properties which are suitably matched to the various needs.
Summary of the Invention A shoe lift constructed in accordance with this invention comprises a replaceable lift attached to the bottom of the heel of the shoe. The lift is molded from two resin layers, upper and lower, and, in addi-tion to one of these two resin layers ~eing molded froma hard resin and the other being molded from a rela-tively soft resin, in order to mold the upper and lower resin layers into a single piece, connecting holes are formed in one of the layers and connecting projections are formed in the other layer. In addition, in this composition, the upper layer i8 a nylon resin layer and the lower layer is a urethane resin layer.
.
~' "' .
.
2072~
With the composition described above, by molding the lift into two layers, upper and lower, it is possible to mold the upper and lower layers from resin layers having properties which are suitably matched to the various needs. In other words, if one of the upper and lower layers is molded from a hard resin layer and the other from a relatively soft resin layer, the shock-absorbing action of the soft resin layer prevents the impact force from the floor from ~0 reverberating to the head of the wearer, thus both improving the health aspect and also providing good wearing comfort. In addition, the hard resin layer makes it possible to ensure sufficient rigidity for the entire lift, thus eliminating the danger of the wearer twisting an ankle as a result of the manner in which the weight of the wearer is applied while walking which might cause the lift to tilt sideways. Furthermore, it is possible to select different coloring for the upper and lower layers, and in particular, if the lower layer is a urethane resin layer, a bright, natural color can be easily used, thus making it possible to prevent marking of a floor surface.
Brief Description of the Drawinqs The following is a description of an embodi-ment of the invention, given with reference to the figures of the accompanying drawings, wherein:
Fig. 1 is a perspective view of the heel part of a shoe incorporating the present invention;
Fig. 2 is an enlarged side view of the heel'~ 0 part with some parts in section;
Fig. 3 shows four diagrams (a), (b), (c) and (d) in schematic form, of steps in molding a shoe lift;
Figs. ~(a) and 4(b) are a pla:n view and a perspective view of the lower layer of the lift showing an example of the connecting projections;
~igs. 5(a) through 5 (G) are plan ~iews of the lower layer of the lift showing various styles of 10 connecting projections; and ~:
Figs. 6(a) and 6(b) show additional embodi- :
ments of the lift construction.
Detailed Description of the Invention Although the shoe in the embodiment shown in Figs. 1 and 2 is a type of a woman's shoe, the inven-tion is also equally applicable to a man's shoe. The shoe comprises a shoe body 1, a heel body 2 made of, in this specific example, rigid plastic which p~ojects from the bottom rear of the shoe body 1, and a two-lay-er molded lift 3 which is attached to the bottom ofthis heel body 2 and which will be described later.
The heel body 2 may also be molded into two separate layers, upper and lower.
The heel body 2 described above i~ attached as a continuous single piece to the bottom of the shoe , .
body 1, and a wedge-shaped notch 4 (see Fig. 2) whi ~ 7 g~
tapers in the inward and downward direction is formed at the bottom of the heel body 2. In addition, an insertion hole 5 is formed in the center part of the bottom of the heel body 2. The hole 5 i9 substantially perpendicular to the bottom surface 2a of the body 2.
metal mounting fixture 6 which projects upwardly from the top of the horseshoe-shaped lift 3 extends into this insertion hole 5, so that, as shown in Fig. 2, the heel body 2 and the lift 3 are connected together as a single piece. The mounting fixture 6 has a head or flange 6a at its bottom, and this flange 6a is embedded into the lift 3 so that the mounting fixture is secured to the lift 3 as a single piece. In addition, multiple vertical grooves are formed into the circumference of a shank or insertion part 6b of the mounting fixture 6 for the purpose of increasing the adhesio~ and also preventing the lift 3 from turning. The hole 5 and the insertion part 6b have mating cross-sectional shapes and the part 6b is sized to fit tightly in the hole 5.
The notch 4 is used when removing a worn lift 3 from the heel body 2 in order to replace it. In other words, by inserting the tip of a screwdriver or similar tool D into the notch 4 as indicated by the imaginary lines in Fig. 2, the lift 3 can be pried loose and removed from the heel body 2 by the principle of lever-age. It should be noted that, because the notch 4 is provided on the inward-facing side of the bottom of the heel body 2, even if, for example, there is no outer covering ~wrapping) around the heel, it is not espe-, ciall~ visible from the outside, and thus there is noimpairment to the appearance of the shoe.
The following is a detailed explanation of the lift construction of this invention.
As shown in Fig. 2, the lift 3 i9 molded from two resin layers, an upper layer 3A and a lower layer 3B. In other words, the lift 3 is not a solid piece made entirely of a single resin, as in the prior art, but is comprised of two resin layers, the upper layer 3A and the lower layer 3B, which divide it vertically into two approximately equal halves. For example, of the upper and lower layers, one layer is molded from ~
hard nylon resin, and the other layer is molded from ~-relatively softer urethane resin. Rather than using two different resins for the upper an~ lower layers, it is also possible to mold both the upper and the lower layers from the same resin, for example, urethane. If different resins are used for the upper and lower layers, it becomes easy to provide each layer with the mechanical properties which meet the corresponding needs required of that layer. Of course, even if both layers are molded from the same resin, it is also possible to allot different hardnesses or other proper-ties to the upper and lower layers. The reason why a relatively soft resin layer is used for one of the two layers is that, by providing that layer with a shock-absorbing function, the impact shock generated while walking on a hard surface does not reverberate to the head of the wearer, thus improving the health aspect, 2 weariny comfort, etc.
In addition, the reason for specifically using a urethane resin layer for the lower layer 3B is that, because the black coloring (colored with carbon black) used in order to present a slim appearance couId result in marks being made on the floor surface whi.le walking, this is prevented by allotting urethane resin for the lower layer and utilizing its bright, natural color.
Furthermore, the reason for composing either the upper layer or the lower layer from a hard resin is that, if the upper layer 3A and the lower layer 3B were both molded into a single piece from the same ~oft resin, the entire lift 3 would lack rigidity, and the manner in which the weight of the wearer is applied while walking could cause the lift to tilt sideways, thus presenting the danger that the wearer may twist an ankle; however, by composing a layer which comprises one-half of the lift from a hard resin layer, it is possible to provide the rigidity required for the entire lift, thus eliminating such danger.
By molding the lift into two layers, upper and lower, in this way, it becomes possible to appro-priately select resins having properties which aresuitably matched to the various needs and to allot them to the upper and lower layers, and, in particular, because it is possible to mold the two layers from different resins, it thus becomes possible to achieve a lift which has multiple composite function~. 2 The upper and lower resin layers which com-prise the lift construction of this invention are not connected together into one piece by adhesive, but are composed so as to form a single piece by a male-female dovetail type of connection in the molding stage, as will be described later. In other words, as shown in Fig. 2, multiple connecting projections 3b are formed so that they project from the top of the resin layer of the lower layer 3B and fit into connecting holes 3a formed in the resin layer of the upper layer 3A in order to connect the two layers together into one piece. The reason for using this type of connection is that, although connection by adhesive might be con~id-ered i~ ord~r to utilize the good adhesion of the two layer~ if urethane resin layers are used for both the upper and lower layers, if this method were used, adhesive material could protrude from the adhesion surfaces, thus impairing the external appearance. In addition, another reason is to make it possible to also use nylon resins or the like having poor adhesion properties as one of the resins which compose the material oE the lift.
- 25 With the lift construction of this invention as described above, it is possible to manufacture it by injection molding. The ~ollowing i9 a description of the lift molding method based on the schematic diagrams shown in Fig. 3.
In step (a) of Fig. 3, the mounting fixture 6 described earlier is first placed and secured in t prescribed location in a die (female die) 7 having projections 7a of trapezoidal cross-sections inside it.
A male die or cover 8 is set in place on the die 7, forming a cavity 3A' which forms the upper layer of the lift inside the dies. Then, after the dies 7 and 8 are secured, the prescribed molten resin (for exam~le, urethane resin~ is injected in through an injection port 8a. The flange 6a is exposed on its top and bottom sides. When this resin is injected, the molten resin also flows into the space between the flange 6a of the mounting fixture 6 and the die 7, thus embedding and securing the mounting fixture 6 in the resin.
After the resin has been in;ected and solidi-fied, the dies are opened and a molded piece which corresponds to the upper layer of the lift plu9 the fixture 6 is released from the dies.
Due to the trapezoidal shape of the projec-tions 7a, parts of this molded piece are thus formedinto trapezoidal cavities 3a having a reverse taper, i.e. the connecting holes 3a.
In step (b), the molded piece which corre-sponds to the upper layer 3A of the lift i9 then placed inside a different female die 9 and a cover die 8 is placed in position in the same way as just described, as shown in step (c).
With reference to step (c), the inside of this die is formed with a cavity 3B' for the purpos~ ~f~
molding the lower layer 3B oE the lift. The layer 3A
is placed on a flat bottom surface 9a of the cavity 3B', and the shank of the mounting fixture 6 extends downwardly into a hole 9b in the die 9 at the bottom of the cavity 3B'. The side walls 9C of the cavity 3B~
fit snugly against the outer sides of the layer 3A.
After the dies 8 and 9 are secured, molten resin (for example, nylon resin) is injected in through the injec-tion port 8a. This nylon resin also fills the connect-ing holes:3a ha-vin~ a trapezoidal cross-section with a reverse taper which were formed in the resin of the upper layer 3A. After the injected resin solidifi.es, the dies are opened, the molded piece is released and removed from the dies, and thus the molded lift of this invention shown in step (d) is obtained.
Because the connecting holes 3a mentioned above are formed with a reverse-taper trapezoidal cross-section, when they become filled by the lower layer resin, reverse-taper connecting projections 3b are formed. Thus a dovetail type of connection between the layers is formed, thereby forming or connecting the resin layer of the lower layer 3B into essentially one piece with the resin layer of the upper layer 3A in such a manner that it i9 almost impossible for them to become separated. In this lift construction, the connecting holes 3a are formed as through holes in order to make it possible to open the dies. For the shape or positioning of the connecting projections 3b which fit into the connecting holes 3a, for example, as shown in Fig. ~, conically shaped or mushroom-shaped2~7 connecting projections 3b are formed on the surface of the horseshoe-shaped lower layer 3B in approximately three or four locations according to the amount of surface area. In addition, as shown in Fig. 5, avoid-ing the space occupied by the flange 6a of the mounting fixture 6, it is also possible to form a continuous U-shaped connecting projection 3b (Fig. 5(a)) or to form two longitudinal or lateral elongated connecting projections 3b (Figs. 5(b) and 5(c)).
In Fig. 6, if insert dies are used in order to make it possible to open the dies, it then becomes possible to connect the lift into one piece without using through-holes for the connecting holes as is the case in the embodiment explained above. Fig. 6(a) shows an example of screwhead-shaped connecting projec-tions 3b, and Fig. 6(b) shows an example of knob-shaped connecting projections 3b. In either case, in the same way as in the embodiment described above, the upper and lower layers are composed in such a manner that it is impossible for them to become separated.
A shoe lift according to this invention has numerous advantages as follows:
5 (1) By molding the lift in two layers, upper and lower, it is possible to select resin materi-als having properties which are suitably matched to the various needs and to allot them to the upper and lower layers. In other words, if one of the upper and lower layers~ ~ 8 is molded from a hard resin and the other :
layer from a relatively soft resin, it is possible to obtain a lift construction which ~:
has advantages with regard to both health and wearing comfort, with none of the impact :
shock from the floor re~erberating to the head of the wearer, while at the same time ensuring sufficient rigidity for the entire :
lift.
(2) It is possible to use different coloring for the upper and lower layers, and, in particu-lar, if the lower layer is molded from ure-thane resin and a bright, natural color lg used, it is possible to prevent marking of the floor surface.
(3) Because it is possible to mold the two-layer lift construction of this invention into one piece as an injection-molded product, it is possible to obtain a lift having a beautiful finish and a high product value at a reason-able cost.
In consideration of the factors described above, it is a general object of this i.nvention is to provide a lift construction which increases the product value of the shoe, by molding a replaceable lift into a single piece from two resin layers, upper and lower, and, moreover, by selecting resins having properties which are suitably matched to the various needs.
Summary of the Invention A shoe lift constructed in accordance with this invention comprises a replaceable lift attached to the bottom of the heel of the shoe. The lift is molded from two resin layers, upper and lower, and, in addi-tion to one of these two resin layers ~eing molded froma hard resin and the other being molded from a rela-tively soft resin, in order to mold the upper and lower resin layers into a single piece, connecting holes are formed in one of the layers and connecting projections are formed in the other layer. In addition, in this composition, the upper layer i8 a nylon resin layer and the lower layer is a urethane resin layer.
.
~' "' .
.
2072~
With the composition described above, by molding the lift into two layers, upper and lower, it is possible to mold the upper and lower layers from resin layers having properties which are suitably matched to the various needs. In other words, if one of the upper and lower layers is molded from a hard resin layer and the other from a relatively soft resin layer, the shock-absorbing action of the soft resin layer prevents the impact force from the floor from ~0 reverberating to the head of the wearer, thus both improving the health aspect and also providing good wearing comfort. In addition, the hard resin layer makes it possible to ensure sufficient rigidity for the entire lift, thus eliminating the danger of the wearer twisting an ankle as a result of the manner in which the weight of the wearer is applied while walking which might cause the lift to tilt sideways. Furthermore, it is possible to select different coloring for the upper and lower layers, and in particular, if the lower layer is a urethane resin layer, a bright, natural color can be easily used, thus making it possible to prevent marking of a floor surface.
Brief Description of the Drawinqs The following is a description of an embodi-ment of the invention, given with reference to the figures of the accompanying drawings, wherein:
Fig. 1 is a perspective view of the heel part of a shoe incorporating the present invention;
Fig. 2 is an enlarged side view of the heel'~ 0 part with some parts in section;
Fig. 3 shows four diagrams (a), (b), (c) and (d) in schematic form, of steps in molding a shoe lift;
Figs. ~(a) and 4(b) are a pla:n view and a perspective view of the lower layer of the lift showing an example of the connecting projections;
~igs. 5(a) through 5 (G) are plan ~iews of the lower layer of the lift showing various styles of 10 connecting projections; and ~:
Figs. 6(a) and 6(b) show additional embodi- :
ments of the lift construction.
Detailed Description of the Invention Although the shoe in the embodiment shown in Figs. 1 and 2 is a type of a woman's shoe, the inven-tion is also equally applicable to a man's shoe. The shoe comprises a shoe body 1, a heel body 2 made of, in this specific example, rigid plastic which p~ojects from the bottom rear of the shoe body 1, and a two-lay-er molded lift 3 which is attached to the bottom ofthis heel body 2 and which will be described later.
The heel body 2 may also be molded into two separate layers, upper and lower.
The heel body 2 described above i~ attached as a continuous single piece to the bottom of the shoe , .
body 1, and a wedge-shaped notch 4 (see Fig. 2) whi ~ 7 g~
tapers in the inward and downward direction is formed at the bottom of the heel body 2. In addition, an insertion hole 5 is formed in the center part of the bottom of the heel body 2. The hole 5 i9 substantially perpendicular to the bottom surface 2a of the body 2.
metal mounting fixture 6 which projects upwardly from the top of the horseshoe-shaped lift 3 extends into this insertion hole 5, so that, as shown in Fig. 2, the heel body 2 and the lift 3 are connected together as a single piece. The mounting fixture 6 has a head or flange 6a at its bottom, and this flange 6a is embedded into the lift 3 so that the mounting fixture is secured to the lift 3 as a single piece. In addition, multiple vertical grooves are formed into the circumference of a shank or insertion part 6b of the mounting fixture 6 for the purpose of increasing the adhesio~ and also preventing the lift 3 from turning. The hole 5 and the insertion part 6b have mating cross-sectional shapes and the part 6b is sized to fit tightly in the hole 5.
The notch 4 is used when removing a worn lift 3 from the heel body 2 in order to replace it. In other words, by inserting the tip of a screwdriver or similar tool D into the notch 4 as indicated by the imaginary lines in Fig. 2, the lift 3 can be pried loose and removed from the heel body 2 by the principle of lever-age. It should be noted that, because the notch 4 is provided on the inward-facing side of the bottom of the heel body 2, even if, for example, there is no outer covering ~wrapping) around the heel, it is not espe-, ciall~ visible from the outside, and thus there is noimpairment to the appearance of the shoe.
The following is a detailed explanation of the lift construction of this invention.
As shown in Fig. 2, the lift 3 i9 molded from two resin layers, an upper layer 3A and a lower layer 3B. In other words, the lift 3 is not a solid piece made entirely of a single resin, as in the prior art, but is comprised of two resin layers, the upper layer 3A and the lower layer 3B, which divide it vertically into two approximately equal halves. For example, of the upper and lower layers, one layer is molded from ~
hard nylon resin, and the other layer is molded from ~-relatively softer urethane resin. Rather than using two different resins for the upper an~ lower layers, it is also possible to mold both the upper and the lower layers from the same resin, for example, urethane. If different resins are used for the upper and lower layers, it becomes easy to provide each layer with the mechanical properties which meet the corresponding needs required of that layer. Of course, even if both layers are molded from the same resin, it is also possible to allot different hardnesses or other proper-ties to the upper and lower layers. The reason why a relatively soft resin layer is used for one of the two layers is that, by providing that layer with a shock-absorbing function, the impact shock generated while walking on a hard surface does not reverberate to the head of the wearer, thus improving the health aspect, 2 weariny comfort, etc.
In addition, the reason for specifically using a urethane resin layer for the lower layer 3B is that, because the black coloring (colored with carbon black) used in order to present a slim appearance couId result in marks being made on the floor surface whi.le walking, this is prevented by allotting urethane resin for the lower layer and utilizing its bright, natural color.
Furthermore, the reason for composing either the upper layer or the lower layer from a hard resin is that, if the upper layer 3A and the lower layer 3B were both molded into a single piece from the same ~oft resin, the entire lift 3 would lack rigidity, and the manner in which the weight of the wearer is applied while walking could cause the lift to tilt sideways, thus presenting the danger that the wearer may twist an ankle; however, by composing a layer which comprises one-half of the lift from a hard resin layer, it is possible to provide the rigidity required for the entire lift, thus eliminating such danger.
By molding the lift into two layers, upper and lower, in this way, it becomes possible to appro-priately select resins having properties which aresuitably matched to the various needs and to allot them to the upper and lower layers, and, in particular, because it is possible to mold the two layers from different resins, it thus becomes possible to achieve a lift which has multiple composite function~. 2 The upper and lower resin layers which com-prise the lift construction of this invention are not connected together into one piece by adhesive, but are composed so as to form a single piece by a male-female dovetail type of connection in the molding stage, as will be described later. In other words, as shown in Fig. 2, multiple connecting projections 3b are formed so that they project from the top of the resin layer of the lower layer 3B and fit into connecting holes 3a formed in the resin layer of the upper layer 3A in order to connect the two layers together into one piece. The reason for using this type of connection is that, although connection by adhesive might be con~id-ered i~ ord~r to utilize the good adhesion of the two layer~ if urethane resin layers are used for both the upper and lower layers, if this method were used, adhesive material could protrude from the adhesion surfaces, thus impairing the external appearance. In addition, another reason is to make it possible to also use nylon resins or the like having poor adhesion properties as one of the resins which compose the material oE the lift.
- 25 With the lift construction of this invention as described above, it is possible to manufacture it by injection molding. The ~ollowing i9 a description of the lift molding method based on the schematic diagrams shown in Fig. 3.
In step (a) of Fig. 3, the mounting fixture 6 described earlier is first placed and secured in t prescribed location in a die (female die) 7 having projections 7a of trapezoidal cross-sections inside it.
A male die or cover 8 is set in place on the die 7, forming a cavity 3A' which forms the upper layer of the lift inside the dies. Then, after the dies 7 and 8 are secured, the prescribed molten resin (for exam~le, urethane resin~ is injected in through an injection port 8a. The flange 6a is exposed on its top and bottom sides. When this resin is injected, the molten resin also flows into the space between the flange 6a of the mounting fixture 6 and the die 7, thus embedding and securing the mounting fixture 6 in the resin.
After the resin has been in;ected and solidi-fied, the dies are opened and a molded piece which corresponds to the upper layer of the lift plu9 the fixture 6 is released from the dies.
Due to the trapezoidal shape of the projec-tions 7a, parts of this molded piece are thus formedinto trapezoidal cavities 3a having a reverse taper, i.e. the connecting holes 3a.
In step (b), the molded piece which corre-sponds to the upper layer 3A of the lift i9 then placed inside a different female die 9 and a cover die 8 is placed in position in the same way as just described, as shown in step (c).
With reference to step (c), the inside of this die is formed with a cavity 3B' for the purpos~ ~f~
molding the lower layer 3B oE the lift. The layer 3A
is placed on a flat bottom surface 9a of the cavity 3B', and the shank of the mounting fixture 6 extends downwardly into a hole 9b in the die 9 at the bottom of the cavity 3B'. The side walls 9C of the cavity 3B~
fit snugly against the outer sides of the layer 3A.
After the dies 8 and 9 are secured, molten resin (for example, nylon resin) is injected in through the injec-tion port 8a. This nylon resin also fills the connect-ing holes:3a ha-vin~ a trapezoidal cross-section with a reverse taper which were formed in the resin of the upper layer 3A. After the injected resin solidifi.es, the dies are opened, the molded piece is released and removed from the dies, and thus the molded lift of this invention shown in step (d) is obtained.
Because the connecting holes 3a mentioned above are formed with a reverse-taper trapezoidal cross-section, when they become filled by the lower layer resin, reverse-taper connecting projections 3b are formed. Thus a dovetail type of connection between the layers is formed, thereby forming or connecting the resin layer of the lower layer 3B into essentially one piece with the resin layer of the upper layer 3A in such a manner that it i9 almost impossible for them to become separated. In this lift construction, the connecting holes 3a are formed as through holes in order to make it possible to open the dies. For the shape or positioning of the connecting projections 3b which fit into the connecting holes 3a, for example, as shown in Fig. ~, conically shaped or mushroom-shaped2~7 connecting projections 3b are formed on the surface of the horseshoe-shaped lower layer 3B in approximately three or four locations according to the amount of surface area. In addition, as shown in Fig. 5, avoid-ing the space occupied by the flange 6a of the mounting fixture 6, it is also possible to form a continuous U-shaped connecting projection 3b (Fig. 5(a)) or to form two longitudinal or lateral elongated connecting projections 3b (Figs. 5(b) and 5(c)).
In Fig. 6, if insert dies are used in order to make it possible to open the dies, it then becomes possible to connect the lift into one piece without using through-holes for the connecting holes as is the case in the embodiment explained above. Fig. 6(a) shows an example of screwhead-shaped connecting projec-tions 3b, and Fig. 6(b) shows an example of knob-shaped connecting projections 3b. In either case, in the same way as in the embodiment described above, the upper and lower layers are composed in such a manner that it is impossible for them to become separated.
A shoe lift according to this invention has numerous advantages as follows:
5 (1) By molding the lift in two layers, upper and lower, it is possible to select resin materi-als having properties which are suitably matched to the various needs and to allot them to the upper and lower layers. In other words, if one of the upper and lower layers~ ~ 8 is molded from a hard resin and the other :
layer from a relatively soft resin, it is possible to obtain a lift construction which ~:
has advantages with regard to both health and wearing comfort, with none of the impact :
shock from the floor re~erberating to the head of the wearer, while at the same time ensuring sufficient rigidity for the entire :
lift.
(2) It is possible to use different coloring for the upper and lower layers, and, in particu-lar, if the lower layer is molded from ure-thane resin and a bright, natural color lg used, it is possible to prevent marking of the floor surface.
(3) Because it is possible to mold the two-layer lift construction of this invention into one piece as an injection-molded product, it is possible to obtain a lift having a beautiful finish and a high product value at a reason-able cost.
Claims (4)
1. A shoe lift for a shoe having a heel, said lift comprising an upper resin layer and a lower resin layer, one of said resin layers comprising a hard resin and the other of said layers comprising a rela-tively soft resin, at least one connecting hole being formed in one of said layers and at least one connect-ing projection being formed on the other of said lay-ers, said projection being anchored in said hole and thereby securing said layers together.
2. A shoe lift as described in Claim 1, wherein said layers comprise an upper layer and lower layer, said upper layer being molded from nylon resin and said lower layer being molded from urethane resin.
3. A shoe lift as described in Claim 1, wherein said projection and said hole form a dovetail connection.
4. A shoe lift as described in Claim 1, wherein one of said layers is a molded part and the other of said layers is molded on said part.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP039999U JPH06108U (en) | 1992-06-11 | 1992-06-11 | Shoe lift structure |
| JP4-39,999 | 1992-06-11 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2078755A1 true CA2078755A1 (en) | 1993-12-12 |
Family
ID=12568629
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002078755A Abandoned CA2078755A1 (en) | 1992-06-11 | 1992-09-21 | Shoe lift construction |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0573717A1 (en) |
| JP (1) | JPH06108U (en) |
| KR (1) | KR940000061A (en) |
| CN (1) | CN1079884A (en) |
| CA (1) | CA2078755A1 (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2338397A (en) * | 1998-06-19 | 1999-12-22 | Supadance International Limite | Stiletto heel top piece |
| ES2157756B1 (en) * | 1999-02-05 | 2002-02-16 | Hipolito Garcia S A | PROCESSING MANUFACTURE OF HEELS FOR FOOTWEAR. |
| JP2008264143A (en) * | 2007-04-19 | 2008-11-06 | Tetsushi Nakamura | Top lift, shoe heel and shoe |
| US8484863B2 (en) * | 2009-05-07 | 2013-07-16 | Brown Shoe Company, Inc. | Top lift assembly for a shoe heel |
| JP5889314B2 (en) * | 2010-10-11 | 2016-03-22 | ティービーエル・ライセンシング・リミテッド・ライアビリティ・カンパニー | Suspension heel |
| JP5696436B2 (en) * | 2010-11-04 | 2015-04-08 | アイシン精機株式会社 | Frame mall |
| JP5986517B2 (en) * | 2013-02-19 | 2016-09-06 | 株式会社アシックス | Top lift |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2990627A (en) * | 1958-11-12 | 1961-07-04 | Stubbe Friedrich | Heel lift |
| DE7723365U1 (en) * | 1977-07-27 | 1977-11-10 | Moelde Gustav Moeller Kg, 4930 Detmold | Screw studs for sports shoes |
| AU8318782A (en) * | 1981-05-15 | 1982-11-18 | Dowty Seals Limited | Studs for footwear |
| IT1230453B (en) * | 1989-02-10 | 1991-10-23 | Bramucci Mauro | TOP-HEEL FOR SPIDER HEEL WITH METALLIC CORE AND DOUBLE SOLID COATING OF THERMOPLASTIC RESIN AND RELATED MANUFACTURING PROCEDURE |
| FR2651972B1 (en) * | 1989-09-15 | 1993-12-31 | Manoel Bouchet | PROTECTIVE ELEMENT FOR SHOE NEEDLE HEEL. |
| AU7474391A (en) * | 1990-02-20 | 1991-09-18 | Fisher Camuto Corporation | Shoe with improved dual hardness heel-lift |
-
1992
- 1992-06-11 JP JP039999U patent/JPH06108U/en active Pending
- 1992-09-21 CA CA002078755A patent/CA2078755A1/en not_active Abandoned
- 1992-11-02 CN CN92112784A patent/CN1079884A/en active Pending
- 1992-11-06 KR KR1019920020891A patent/KR940000061A/en not_active Application Discontinuation
- 1992-12-21 EP EP92311666A patent/EP0573717A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| KR940000061A (en) | 1994-01-03 |
| EP0573717A1 (en) | 1993-12-15 |
| JPH06108U (en) | 1994-01-11 |
| CN1079884A (en) | 1993-12-29 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |