US3685071A

US3685071A - Method of making shoes

Info

Publication number: US3685071A
Application number: US68419A
Authority: US
Inventors: Peter D J Dicks; William M Hill
Original assignee: MEL HILL TECHNICAL DEV Ltd
Current assignee: MEL HILL TECHNICAL DEV Ltd
Priority date: 1970-08-31
Filing date: 1970-08-31
Publication date: 1972-08-22
Anticipated expiration: 1989-08-22
Also published as: NL7116053A

Abstract

A method of forming a shoe comprising the steps of forming the upper formation from a plastic material by electrostatic deposition on a mould, removing the plastic moulded upper formation from the mould and uniting the lower marginal portion of the upper formation to a sole.

Description

United States Patent Dicks et al.

[54] METHOD OF MAKING SHOES [72] Inventors: Peter D. J. Dicks, Kitchener, On-

tario; William M. Hill, Ayr, Ontario, both of Canada [73] Assignee: Mel Hill Technical Developments Limited, Preston, Ontario, Canada [22] Filed: Aug. 31, 1970 [21] Appl. No.: 68,419

52 US. Cl. ..12/l46 c 51 1111.01. ..A43d [58] Field 01 Search ..12/142 R, 142 15,142 RS,

[56] References Cited UNITED STATES PATENTS Dicksetal ..12/142EX 15] 3,685,071 1451 Aug. 22, 1972 3,101,496 8/1963 Bingham et al. 12/142 E 1,206,914 12/1916 Price ..l2/142 E 2,582,298 1/1952 Ushakoif ..12/146 C 2,904,838 9/1959 Phillips 12/146 C Primary ExaminerPatrick D. Lawson Att0rneyFetherstonhaugh & Co.

[5 7 ABSTRACT A method of forming a shoe comprising the steps of forming the upper formation from a plastic material by electrostatic deposition on a mould, removing the plastic moulded upper formation from the mould and uniting the lower marginal portion of the upper formation to a sole.

13 Claims, 9 Drawing Figures PATENTEflIIIcza I972 3.685.071

sum 1 BF 3 yM/Q7/1 ATTORN EYS PATENTEDAUG 22 1912 SHEET 2 OF 3 FIGZb INVENTORS PETER D. J. D/CKS BalWLL/AM M. HILL flawa ak ATTORNEYS PATENTED M192 2 I972 SHEET 3 BF 3 I 'E.\ TURS PETER D. J. DICKS ATTORNEYS METHOD OF MAKING SHOES This invention relates to the manufacture of shoes. In particular, this invention relates to an improved method of manufacturing shoes wherein the shoe upper is made in one piece and subsequently anchored to a sole.

In the manufacture of shoes, it has become common to make the shoe upper formation from plastic material. The production costs can be reduced by substituting plastic material for the traditional leather and the plastic can be given the appearance of high grade leather. A further advantage of the use of plastic material in the formation of the upper is that is it possible to form the sole in an injection moulding process with the plastic upper located in the mould so as to be bonded thereto. This improved method eliminates the costly stitching operations which have long been used in the connecting of the sole of a shoe to the upper when using the traditional leather upper. With these new techniques, production of the upper has not been simplified to any great extent since the practice has been to make an upper from a number of plastic elements having the same general contour as the elements previously employed in making a shoe from leather. These elements are then secured together either by stitching or bonding by an adhesive or a heat sealing operation. In addition, considerable difficulty has been experienced in attempting to securely anchor the upper to an injection moulded sole. Unlike the stitching operation, it is difficult to tell by a visual examination whether or not the connection of the upper to the sole is satisfactory. The problem has been that the marginal edges of the upper are generally straight and when they are moulded into a sole, they are not anchored in any way.

An alternative method of production which is commonly used in the manufacture of boots and the like is referred to as the slush moulding method. In this method, plastic in liquid state is poured into a mould having the shape of the footwear to be produced and the surface layer of the liquid plastic material is chilled on contact with the mould and solidifies in the mould. After a predetermined period of time, the unchilled liquid plastic material is poured out of the mould leaving a coating of plastic on the surface of the mould. The main disadvantage of this method is that it is very difficult to obtain an even thickness of skin throughout the mould. The uneven cooling of the mould causes local thick spots and thin spots in the moulded article.

The present invention overcomes the difficulties of the prior art described above by providing an improved method of manufacturing a shoe wherein the upper formation of the shoe is made in one piece from a plastic material by electrostatically depositing the plastic material in a mould. The moulded upper formation is then removed from the mould and united at the lower marginal portions thereof to a sole. This improved structure eliminates the stitching and sewing of the component parts of the upper and thereby considerably reduces the labor costs in the manufacturing operation. A further feature of the present invention is that it is possible to form the marginal edges of the upper formation with a permanent set so as to be angularly disposed relative to the remaining portions of the upper formation so as to be firmly anchored in a sole formed by an injection moulding process. The electrostatic moulding process is suitable for forming a moulded upper from a number of layers of different plastic material so that it is possible to form the outer layer with a plastic which will readily conform to the surface pattern of the mould while forming one or more inner layers from a plastic having other physical characteristics or a plastic which is less expensive than that used in the formation of the outer surface.

The invention will be more clearly understood after reference to the following detailed specification read in conjunction with the drawings wherein FIG. 1 is a pictorial view of a mould for use in the formation of a shoe upper according to an embodiment of the present invention;

FIG. la is an enlarged detail view of a marginal edge portion of a mould and shoe upper;

FIGS. 2 and 2a are cross-sectional views diagrammatically illustrating the mould of FIG. 1 in operable positions for electrostatic moulding;

FIG. 2b is a plan view of the moulding device of FIG. 20;

FIG. 3 is a cross-sectional view of an upper located in an injection moulding device for forming the sole; and

FIGS. 4 to 6 are cross-sectional views illustrating alternative methods of anchoring the upper to a sole.

The mould 10 illustrated in FIG. 1 of the drawings consists of a shoe-shaped moulding portion having a cavity 11 conforming to the exterior shape of the upper which is to be produced in the mould and a flange 16. The mould cavity 1 1 may also be fonned with a desired surface pattern and with imitation stitching seams such as illustrated at 14 in FIG. I. The flange 16 extends outwardly from the mould 10 serves to assist in locating the mould 10 relative to an electrostatic coating apparatus. In FIG. 1a, it will be noted that at the edge connection between the shoe-shaped portion of the mould and the flange 16, there is a short obliquely extending wall portion 18. This wall portion 18 serves to form the marginal edge of the moulded upper at an angle relative to the adjacent portions of the shoe to provide an anchoring marginal edge or lip as will be described hereinafter.

One of the advantages of the electrostatic moulding process is that a mould can be made at a much lower cost than a mould for injection moulding. To make the mould for a shoe, a shoe is first made in a conventional manner as by stitching the various panels together. A mould is then made from the shoe in urethane or rubber or the like. The hollow master mould is then supported in a jig to retain its shape and filled with wax or the like. The urethane or rubber mould is then removed leaving a solid plating master. The wax master is then plated by a vapor deposition of nickel about 0.030 to 0.040 inches on the solid master. The wax is then melted to leave the nickel mould with a cavity conforming to the configuration of the outer surface of a shoe upper as shown in FIG. 1 of the drawings. The small obliquely disposed edge 18 is formed in the mould by making minor modifications to the urethane or rubber mould. One of the features of making a mould in the manner previously described is that it is possible to produce a mould which will have a surface pattern conforming very closely to the pattern on the original shoe. As a result, it is possible to pick up the leather grain pattern in fine detail.

After the mould has been made, it is transferred to an electrostatic moulding apparatus of a known type such as that described in our US. Pat. No. 3,369,274, dated Feb. 20, 1968. FIG. 2 illustrates a diagrammatic illustration of a mould mounted in a rotating drum such as that described in our US. Pat. No. 3,369,274. In this apparatus the plastic is applied to the mould by way of spray heads 17. The charged plastic particles are sprayed onto the surface of the mould cavity to conform to the shape of the cavity. The mould 10 is heated in the moulding apparatus in a conventional manner. The operation may be carried out in one or more stages to provide a laminated upper formation from preselected plastic materials. For example, an upper may be made from an outer layer of vinyl, an inter mediate layer of vinyl foam and an inner layer of polypropyl fibers, each being applied in successive electrostatic moulding operations. Numerous other plastic materials may also be used as, for example, polyvinylchloride, polyethylene and elastomers. In addition, material such as cotton and rayon fibers may be applied to the molten plastic by an electrostatic flocking process.

It will be noted that this method also provides a con venient method of applying a flock coating to the interior of the upper. For example, it is possible to flock coat polypropylene fibers onto the surface of the vinyl when the vinyl is at a temperature suitable for receiving and bonding the fibers thereto. It is a characteristic of flock coating that the electrostatically charged particles tend to stand on end and, therefore, a deep pile coating can very easily be applied by this method. This method of forming a multi-layered and lined upper provides a substantial advantage over any other form of plastic moulding in view of the fact that it can be carried out in the same mould. A further feature of the electrostatic moulding process is that the thickness of the plastic material which is moulded is substantially uniform.

After the upper has been formed, it is cured by heating in the usual manner and then it is removed from the mould 10. Generally the upper can be removed very easily by manually gripping an edge and pulling it out. If a mould has not been treated to ensure that plastic does not adhere to the portion overlying the leg opening of the shoe, it may be necessary to cut the opening in the shoe. This could, of course, be eliminated by applying a coating of an insulating material to the area of the mould overlying the leg opening and thereby ensuring that the electrostatically charged particles will not be retained by the mould in this area. After the moulded upper formation is removed from the mould 10, it is transferred to an injection mould such as that shown in section in FIG. 3. This mould may be substantially the same as the moulds presently in use for injection moulding of the sole of a shoe and the embodiment illustrated in FIG. 3 is only meant to be a diagrammatic representation of known moulding apparatus. In this apparatus, the mould cavity 24 is formed between split moulds 26 and interior mould plate 28. The moulds 26 and plate 28 are designed to provide a clearance for receiving the upper formation 12 in a close fitting relationship so as to grip the upper formation 12 therebetween with the marginal edge thereof extending downwardly into the mould cavity 24. It will be noted that the lip 18 of the upper 20 is located substantially centrally of the thickness of the mould cavity. In this position, when the mould is filled by injection moulding, the lip 18 will be anchored within the sole to form a mechanical connection therewith in addition to the welding which takes place. Normally a vinyl upper will be rendered plastic at about 340 while the urethane or vinyl sole will be injected at a temperature of about 430 so that there will be substantial welding between the vinyl upper and the injection moulded sole.

In FIGS. 4, 5 and 6 of the drawings, alternative forms of anchoring lips are illustrated. Each of these forms may be produced in the electrostatically formed upper by preparing the mould accordingly. The formation of the marginal edge in any one of the forms illustrated in FIGS. 4 to 6 serves to firmly anchor the upper formation in the injection moulded sole. While shoe soles have previously been formed by injection moulding with the upper having a marginal edge located in the mould, it has not previously been possible to form the marginal edge with a permanent set so as to provide a mechanical lock when the moulding has been completed.

FIG. 2a and FIG. 2b illustrate a further feature of the invention. In this embodiment the electrostatic coating is applied by an electrostatic fluidized bed 17a and a portion of the mould is screened by a movable slide 30. The slide 30 is carried by a shaft 32 which is slidably driven by means of a solenoid valve 34 into and out of a position underlying the mould cavity. The valve 34 is mounted on a platform which extends outwardly from the fluidized bed. This arrangement enables selected portions of the mould cavity to be screened while others are exposed to permit a localized increase in the thickness of the predetermined portions of the upper. It will be understood that a similar result may be achieved by moving the mould from one moulding station to another and screening certain portions of the subsequent moulds. For example, an even coating of plastic may be applied to the mould in the first moulding station and an additional localized thickness of the same or a different material may be applied in the second moulding station by screening selected areas of the mould. The method wherein the mould is indexed from one station to another is of particular advantage when the layers of material which are to be applied in the second moulding operation are formed from a different material to that in the first moulding operation.

These and other modifications of the present invention will be apparent to those skilled in the art without departing from the scope of this invention.

What we claim as our invention is:

l. A method of forming a shoe comprising the steps of forming the upper formation from a plastic material by electrostatic deposition on a mould and thereafter screening a portion of the mould and electrostatically depositing additional plastic material on the unscreened portion of the preformed upper to reinforce the unscreened portions by increasing the thickness thereof, curing said plastic material, removing the plastic moulded formation from the mould and uniting the lower marginal portion of the upper formation to a sole.

2. A method according to claim 1 wherein said additional plastic is applied before the plastic of the first formed upper is cured.

3. A method according to claim 1 wherein said additional plastic is applied after the plastic of the first formed upper is cured.

4. A method of forming a shoe comprising the steps of forming the upper formation from a plastic material by electrostatic deposition of the plastic material on a mould, curing said plastic material, removing the plastic moulded upper formation from the mould, applying a liner to said upper formation and uniting said upper formation and liner to a sole.

5. A method of forming a plastic shoe upper which has at least two areas in which the wall thickness is different from one another including the steps of:

a. electrostatically depositing plastic material in a mould formed to the contour of the upper and curing said plastic material and removing the moulded upper from the mould, and

. screening at least a portion of said mould during a predetermined portion of the time during which said plastic material is being deposited whereby the thickness of plastic material deposited on the screened portion is less than that deposited on the unscreened portion.

6. A method of forming a plastic shoe upper as claimed in claim 5 wherein said screening takes place after a substantially uniform coating of plastic material has been applied to the mould.

7. A method as claimed in claim 6 wherein said additional plastic material is applied before the plastic of a first formed upper portion is cured.

8. A method according to claim 6 wherein said additional plastic material is applied after the plastic of the first formed upper is cured.

9. A method of forming a shoe which has an upper and a sole portion and wherein the upper portion has at least two areas in which the wall thickness is different from one another including the steps of:

a. electrostatically depositing plastic material in a mould formed to the contour of the upper and curing said plastic material and removing the moulded upper from the mould,

b. screening at least a portion of said mould during a predetermined portion of the time during which plastic material is being deposited, whereby the thickness of plastic material deposited on the screened portions of the mould is less than that deposited on the unscreened portions of the mould, and

c. uniting the lower marginal portion of the upper formation to a sole.

10. A method of forming a shoe which consists of an upper portion and a sole and wherein the upper portion has a toecap portion of a greater thickness than the remainder of the upper, including the steps of:

a. electrostatically depositing plastic material in a mould formed to the contour of the upper and curing the plastic material while removing the moulded upper from the mould,

. screening all but the toecap forming portion of the mould during a predetermined portion of the time during which the plastic material is being deposited whereby the thickness of plastic material deposited in the toecap forming portion of the mould is greater than that deposited in the remainder of the mould whereby the toecap portionof the mould is reinforced, and c. uniting the lower marginal portion of the upper to a sole.

11. A method of forming a shoe upper comprising the steps of, forming a unitary shoe upper having a free marginal edge at the lower end thereof by electrostatic deposition of plastic material on a mould having an open cavity formed to the required contour of the upper, applying a liner by means of an electrostatic flock coating process to the uncured plastic material, curing said plastic material and removing the cured upper from the mould.

12. A method of forming a shoe comprising the steps of forming a unitary shoe upper having a free marginal edge at the lower end thereof by electrostatic deposition of plastic material on a mould having an open cavity formed to the required controu of the upper, applying a liner by means of an electrostatic flock coating process to the uncured plastic material, curing said plastic material, removing the cured upper from the mould and uniting the cured upper to a sole.

13. A method of forming a shoe as claimed in claim 1 including the step of applying a liner to the uncured plastic material by means of an electrostatic flock coating process.

Claims

1. A method of forming a shoe comprising the steps of forming the upper formation from a plastic material by electrostatic deposition on a mould and thereafter screening a portion of the mould and electrostatically depositing additional plastic material on the unscreened portion of the preformed upper to reinforce the unscreened portions by increasing the thickness thereof, curing said plastic material, removing the plastic moulded formation from the mould and uniting the lower marginal portion of the upper formation to a sole.

5. A method of forming a plastic shoe upper which has at least two areas in which the wall thickness is different from one another including the steps of: a. electrostatically depositing plastic material in a mould formed to the contour of the upper and curing said plastic material and removing the moulded upper from the mould, and b. screening at least a portion of said mould during a predetermined portion of the time during which said plastic material is being deposited whereby the thickness of plastic material deposited on the screened portion is less than that deposited on the unscreened portion.

9. A method of forming a shoe which has an upper and a sole portion and wherein the upper portion has at least two areas in which the wall thickness is different from one another including the steps of: a. electrostatically depositing plastic material in a mould formed to the contour of the upper and curing said plastic material and removing the moulded upper from the mould, b. screening at least a portion of said mould during a predetermined portion of the time during which plastic material is being deposited, whereby the thickness of plastic material deposited on the screened portions of the mould is less than that deposited on the unscreened portions of the mould, and c. uniting the lower marginal portion of the upper formation to a sole.

10. A method of forming a shoe which consists of an upper portion and a sole and wherein the upper portion has a toecap portion of a greater thickness than the remainder of the upper, including the steps of: a. electrostatically depositing plastic material in a mould formed to the contour of the upper and curing the plastic material while removing the moulded upper from the mould, b. screening all but the toecap forming portion of the mould during a predetermined portion of the time during which the plastic material is being deposited whereby the thickness of plastic material deposited in the toecap forming portion of the mould is greater than that deposited in the remainder of the mould whereby the toecap portion of the mould is reinforced, and c. uniting the lower marginal portion of the upper to a sole.

12. A method of forming a shoe comprising the steps of forming a unitary shoe upper having a free marginal edge at the lower end thereof by electrostatic deposition of plastic material on a mould having an open cavity formed to the required contour of the upper, applying a liner by means of an electrostatic flock coating process to the uncured plastic material, curing said plastic material, removing the cured upper from the mould and uniting the cured upper to a sole.