US3681850A

US3681850A - Treatment of footwear

Info

Publication number: US3681850A
Application number: US32278A
Authority: US
Inventors: Alfred Freedman
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-04-27
Filing date: 1970-04-27
Publication date: 1972-08-08
Anticipated expiration: 1989-08-08

Abstract

Footwear is dried in a closed chamber by subjecting it to subatmospheric pressure to cause accelerated evaporation of moisture, solvents etc., therefrom. According to a different embodiment, water is sprayed onto the footwear whilst it is at sub-atmospheric pressure. Atmospheric pressure is then restored to drive the moisture into the footwear. Apparatus includes an open-ended chamber which is closable in pressure-tight fashion by pneumatically-operated doors. Shoe conveyor system extends through chamber to deliver to and remove footwear therefrom.

Description

United States Patent Freedman 51 Aug. 8, 1972 [54] TREATMENT OF FOOTWEAR Oetjen et al. .34115 X 72 l t I 9 3,538,616 ..34/92 I 1 Road, gg 4 Ormgbury 2,216,783 10/1940 Palmer ..34/15 x [22] Filed: April 1970 Primary Examiner-Carroll B. Dority, Jr. [21] AWL NOJ 32,278 Attorney-Larson, Taylor & Hinds [57] ABSTRACT [52] US. Cl. ..34/l, 34/9, Footwear is dried in a dosed hamber by subjecting it I 5 I] Int Cl 801k 5/00 to sub-atmospheric pressure to cause accelerated evaporation of moisture, solvents etc. therefrom. [58] Fleld of Search ..34/l, 9, 15,51, 92 cording to a different embodiment, water is Sprayed 56] Reterences cued onto the footwear whilst it is at sub-atmospheric pressure. Atmospheric pressure is then restored to drive UNI STATES PATENTS the moisteie iato t5: foolttvfiar. Asipargltus includes an open-en c am r w 10 IS cosa e in pressure- 3,32|,842 5/1967 Boccrardo ..34/l5 tight fashion y pneumaticallyflperated doors Shoe 2,373,374 4/1945 Blerwlrth ..34/15 conveyor system extends through chamber to deliver to and remove footwear therefrom. 3:192:645 7/1965 Georg-Wilhem 12 Claims, 6 Drawing Figures A x J QJUCICKJQ 6 PATENTEDAUB 8 m2 SHEET 1 OF 6 DU UU 9 Kw N iilU 33F C i R4 C m PATENTED I 3 I973 PATENTED RUE 3 I973 SHKU i BF 6 PATENTED 81973 3.681.850

SHEET SUF 6 PATENTEU M 3 I972 SHEET 5 OF 6 %\N**NNNH TREATMENT OF FOOTWEAR This invention is concerned with the treatment of articles of footwear during manufacture thereof. Where used in this specification, the term footwear" is in tended to include both complete articles of footwear and components thereof at any convenient stage of manufacture, preparation or after-treatment.

The treatment of footwear during manufacture includes the operations of adding and subtracting water, stress relieving, the removal of solvents in the cement, pufi's, counters etc.

One conventional treatment method is heat setting". In this process, the articles to be treated are mounted on lasts, and advanced through a chamber in which they are subjected to the action of hot moist or hot dry air, for a period of, say 6 minutes. During this period the leather becomes tensioned over the lasts and each shoe upper assumes the shape of the last on which it is mounted. An alternative treatment method is to leave the articles on the lasts for a period of 2 to 3 weeks. The leather dries out during this time and is stress-relieved as it expands and contracts with weather variations. Solvents used in adhesives employed during manufacture of the article evaporate during drying-out of the leather. At the end of the drying-out period, the articles are found to have set in conformity with the shape of the lasts on which they are mounted.

Due to various factors such, for example, as efficient utilization of factory floor space, machinery, lasts and other equipment, it is desirable that well-formed shoes be treated quickly. Manifestly, the last-mentioned method does not fulfil this requirement. Heat setting on the other hand is relatively rapid but has the disadvantage that it does not remove solvents and moisture trapped deep in the materials of the shoe.

An object of the invention is to provide an improved footwear treatment method by which the footwear can be treated in minimum time. A further aim is to provide novel apparatus for performing this method.

Broadly considered, the method according to this invention comprises the step of subjecting the footwear to sub-atmospheric pressure to cause accelerated evaporation of liquid therefrom. It will be appreciated that the term liquid includes not only moisture but also cement solvents, e.g. acetone, etc.

The particular sub-atmospheric pressure to which the articles are subjected depends on conditions. However, in practice, a pressure of the order of 28 29 inches of mercury has been found to give satisfactory results. At this pressure, acetone and other solvents commonly used in adhesives in footwear manufacture also evaporate rapidly.

The period for which the footwear is subjected to sub-atmospheric pressure is preferably comparatively short, e.g. about 6 minutes. This enables the method of the invention to be performed on footwear assembled on a continuous-flow conveyor system and obviates the aforementioned 2 3 weeks drying out period during which, in the case of last-mounted footwear, the lasts are out of use.

in addition, to pennitting efficient treatment of leather, it is found that the method of the invention is eminently suitable for the treatment of synthetic materials used in footwear production e.g. Corfam (Registered Trade Mark).

The method of the invention relies on the well known fact that water boils at C. at atmospheric pressure and at sea level, but at sub-atmospheric pressures will boil at much lower temperatures. It is therefore easier to extract water at sub-atmospheric pressures. This is also true for solvents used in the construction of articles of footwear.

It is also well known that when a liquid evaporates. its temperature drops. Provision must therefore be made to maintain the articles at the required temperature. To this end, the footwear may be either preheated to an elevated temperature before being subjected to sub-atmospheric pressure, orheat may be imparted thereto while they are at subatmospheric pressure.

In the former event, the footwear may be pre-heated by a heat setting process. In view of the fact that the temperature of the air used to treat the footwear during heat setting is usually of the order 100 C, subjection of footwear treated at this temperature to sub-atmospheric pressure causes extremely rapid evaporation of moisture from the footwear.

Where heat is imparted to the articles of footwear whilst they are at sub-atmospheric pressure, radio frequency heating or induction heating may be employed.

It is also proposed, within the scope of the invention, to make the lasts on which the articles of footwear are mounted, at least partly of a heat-conductive material, or to make the lasts of a plastics material and incorporate therein, a conductive or semi-conductive material. In this event, the articles can be heated from inside by subjecting the lasts to radio frequency waves, thereby to raise the temperature of the heat conductive material.

To moisten (or hurnidify) articles of footwear, the preferred method is to remove air from the articles and replace it by a controlled mixture of air and moisture. According to the invention this may be achieved by the step of applying excess moisture to the footwear whilst maintaining the same at sub-atmospheric pressure and then restoring atmospheric pressure.

It is found when using this method that moisture deposited on articles of footwear whilst they are at subatmospheric pressure is drawn into the leather when atmospheric pressure is restored.

The invention also provides apparatus for performing the broad method defined above, this apparatus comprising a chamber which is scalable in pressuretight fashion; pressure-reducing means connected or connectable to the chamber; and means for transporting footwear into and from the chamber.

If desired, means may be provided for imparting heat to the articles whilst they are being introduced into the chamber and/or whilst they are actually being treated in the latter as mentioned above.

Said pressure-reducing means will usually comprise a standard vacuum pump which may include water-extraction means.

The apparatus may be employed to moisten or humidify the footwear by the provision of means for introducing moisture to the chamber at required times for deposition on the articles of footwear.

Preferably, the moisture is introduced into the chamber through one or more spray nozzles arranged to spray water onto the articles at required times to humidify the same.

In order that the invention may be more clearly understood and readily carried into practical effect, one specific embodiment thereof will now be described, by way of example, with reference to the accompanying drawings, wherein FIG. 1 is a diagrammatic plan view of a conveyor system incorporating footwear treatment apparatus in accordance with the invention,

7 FIG. 2 is a detail plan view, partly in section, of the footwear treatment apparatus of FIG. 1,

FIG. 3 is a side view, partly in section, corresponding to FIG. 2,

FIG. 4 is a sectional view on line IV IV of FIG. 3,

FIG. 5 is a perspective view from one side of part of the apparatus shown in FIGS. 2 to 4, and

FIG. 6 is a side view, partly in section, of further apparatus for incorporation in the conveyor system of FIG. 1.

Referring to the drawings, the conveyor system will first be generally described:

The system is, in fact, of the kind forming the subject of my prior U.K.betters Pat. No: 1,076,412 dated Aug. 13 1965. It comprises a trackway l for a plurality of wheeled work carriers 2. As can be most clearly seen in FIG. 4, the trackway is in the form of a main channel 3, along the base of which run the wheels 4 of the carriers, and a sub-channel 5 which depends from channel 3 and carries the driving means for the carriers 2. This driving means consists of an endless band 6 of flexible steel which has a continuous series of teeth 7 along its upper edge and is received in slotted nylon guide blocks 8 (FIG. 2) which are spaced at intervals along the base of sub-channel S and support the band 6 in a vertical disposition with its teeth 7 projecting above the base of the main channel 3 for engagement with catch means (to be described) on the underside of each of the carriers 2. The band 6 is adapted to be reciprocated to and fro in the slots in guide blocks 8 in use to drive the carriers 2 (see below).

The trackway 1 is arranged in two parallel runs 9, the adjacent ends of which are connected by curved runs 9a. At each of these runs 9a, the sub-channel 5 of the trackway 1 is cut away and the band 6 is secured to the peripheries of the relevant one of two drums l0 and 11. Both drums are turnable about vertical axes, drum 10 being freely tumable whilst drum 11 is driven from a power unit 12. Unit 12 is constituted by an electric motor in this embodiment, the output shaft 12a of which is vertically disposed and carries a radial arm 13. Shaft 14 on which drum I1 is mounted, also carries a radial arm 15, the ends of the two

arms

13 and 15 being connected by a link 16. Thus, the arrangement is such that, when motor 12 is in operation, shaft 120 and arm 13 are continuously rotated which causes arm 15 and hence also drum 11 to be oscillated. This causes a reciprocation of band 6 secured to drum 1 1.

Each of the carriers 2 in the system comprises a robust pressed sheet-metal body 17 having downtumed sides 18 which support axles 19 for the front and rear wheels 4. Ajack pin 20 upstands from the body 17 of each carrier to receive a last L (see FIG. 4) on which are mounted articles of footwear F. A loading hook 21 (see FIG. 4) is also provided on each carrier 2 to carry articles not mounted on a last, e.g. shoe uppers.

The above-mentioned catch device with which each carrier 2 is provided comprises a metal strip 22 which runs along the central longitudinal axis of the carrier at its underside and has a pair of depending side flanges at its rear end which are mounted on the axle 19 of the rear wheels 4 of the carrier 2.

One end of strip 22 emerges from the front end of the carrier where it is turned upwardly. A short distance in from this end, strip 22 carries the catch proper. It comprises a plate 23 pivoted by its upper comers to a bracket 24 on the underside of strip 22, bracket 24 carrying a stop 240. With the conveyor in use, the teeth 7 on the driving band 6 engage plate 23 when the band is moving in the intended direction of travel of the carriers, thereby bringing the plate into a vertical position against stop 24a and driving the carrier 2 concerned. When however, the band 6 is withdrawn in the opposite direction, plate 23 turns about its pivots and the teeth 7 on the band 6 are drawn idly across its lower edge. Thus, the carriers 2 are intermittently driven by the band 6.

In the event that one carrier runs into or at least approaches the rear end of another carrier, the effect produced in the oncoming carrier is to pivot its catch strip 22 relatively to the axle 19 of its rear wheels 4 and so lift the catch plate 23 out of the path of the driving teeth 7 and bring that carrier to a halt.

As can be seen from FIG. 1, the carriers normally travel around the system in spaced positions past work stations SI and S2 at which operations are performed on the footwear F carried by the carriers.

At a selected location around the system, the trackway is interrupted to accommodate a footweartreatrnent chamber generally designated C. Thus, the trackway terminates adjacent the front and rear ends of the chamber. The driving band 6 also terminates with the trackway, its free ends (one adjacent each end of chamber C) being connected by a link 25 which extends behind chamber C. This link will, of course, reciprocate with the driving band 6.

It will be appreciated that each successive carrier 2 approaching the chamber C will come to rest where the driving band terminates, following carriers running into the rear of the stationary carrier and being disengaged from the drive strip as described above. The result of this is to produce a batch B of stationary carriers in advance of chamber C.

Chamber C is of rectangular shape in cross-section with open ends. A pair of channel-section guides 26 are provided at each end of the chamber and extend one along the top and one along the bottom edge of the end concerned with their channels facing towards one another. Received in each pair of opposed channels is a sliding door 27 which is arranged to be opened and closed by a pneumatic cylinder and ram device 28. The cylinder of this device is carried by a bracket 29, which extends between channel member 26, and on a bracket 30 mounted on the side of the chamber C. The ram of the device extends through bracket 29 and is secured to the door 27. A pair of wheels 31 which run in ball bearings are mounted on the door and run on the outer edge of the lower channel member 26 to ensure correct orientation of the door during extension and retraction of the ram. A rubber sealing strip 32 is provided to seal with the leading edge of the door when it is closed.

Chamber C is of robust steel construction so that, when the doors 27 are both closed, it is pressure-tight and its walls are able to withstand a considerable reduction in internal pressure.

Three rectangular apertures are formed in the side of chamber C. Mounted on the wall of the chamber and arranged to normally close, two of these apertures are a pair of pneumatically-operated

valves

33, 34. Valve 33 is connected to a vacuum pump 35 and water extractor 36 when in its open condition. Valve 34 on the other hand is arranged, when open, to connect the interior of the chamber to atmosphere. For the sake of convenience, details of the pneumatic piping to

valves

33 and 34 has been omitted.

The third aperture is used to mount a water spray device (to be described later) when required, being closed by a rectangular plate 37 bolted to the wall of the chamber when not in use.

The equipment for introducing the batch B of carriers into chamber C will now be described.

Mounted on a support at the inner side of the trackway is a reversible electric motor 38 arranged with its drive shaft 39 horizontal. As can be seen in FIG. 3, this shaft carries a sprocket and drives, via a chain 40, a larger sprocket 41 mounted on a further horizontal shaft 42. Shaft 42 extends beneath the trackway 1 (FIG. 4) and receives a further sprocket 43 at its outer end. This sprocket drives an endless chain 44 around an idler sprocket 45, the arrangement being such that chain 44 travels in two parallel runs, the upper of which extends beneath the main channel 3 of the trackway 1 at one side of sub-channel 5. Mounted on chain 44 by a pin which replaces the hinge pin between two adjacent links is a link 46 carried on the underside of a slide 47 which rests in the bottom of the trackway. A slot 48 in the base of the trackway allows the slide 47 to move forwardly (i.e. in the direction of travel of the carriers) at required times. Pivotally mounted in the recesses in the slide are a pair of catch members 49 each of which is spring-urged upwardly for engagement with the front axles of the carriers 2. As can be seen, one catch is arranged at the free end of slide 47 (i.e. the end nearest chamber C) whilst the other is, in FlG. 3, arranged to engage the rearrnost carrier 2 in batch B.

In operation, the doors of chamber C open, whereupon motor 38 is operated to move the slide 47 in the forward direction until it extends right into chamber C; at this time link 46 has moved to a position around sprocket 45 which corresponds to the position in which it is shown on sprocket 43, in FIG. 3. Motor 38 then stops. The effect of this is that the catch 49 at the front end of slide 47 engages the rearmost carrier in chamber C and, by abutment with the remaining carriers in the chamber pushes the carriers from the chamber whereupon the ejected carriers are re-engaged by the driving band 6 and continue to be driven around the trackway. At the same time, the carriers in batch B are drawn into chamber C by the other catch 49 operating in similar fashion.

in operation, when the apparatus of the invention is to be used for drying the articles of footwear F, a batch of carriers is inserted in the chamber as described above and the doors are closed. Valve 33 is then opened and valve 34 closed. By operating the vacuum pump 35, chamber C is evacuated to a pressure in the region of 22 to 28 inches of mercury. A vacuum gauge 50 in the wall of the chamber indicates the pressure in the latter. This causes moisture, solvents, etc., in the article F to evaporate, these constituents being removed by extractor 36. At the end of the treatment operation, valve 33 is closed and valve 34 opened to reinstate atmospheric pressure in the chamber and allow the doors to be opened for removal of the carriers therein.

The apparatus is preferably controlled automatically by means of a settable timer which determines the time for which the articles remain in chamber C, and by micro-switches arranged for contact by the various moving parts of the apparatus. Safety devices are also incorporated in the control system, for example to prevent the doors 27 closing in the event that a trolley accidentally comes to rest in the path of one of them.

To maintain the articles at a temperature above the evaporation temperature of the moisture and solvents at the particular pressure prevalent in the chamber in use, means may be provided to impart heat to the articles F whilst they are actually inside the latter. For this purpose, radio frequency heating, or induction heating may be employed. In this event, the lasts L on which the articles F are mounted may be made at least partly of a heat-conductive material, or of a plastics material in which a heat-conductive material is incorporated. The articles can then be heated from inside by subjecting the lasts to radio frequency waves which raise the temperature of the heat-conductive material.

In one method of induction heating, lasts made of aluminum are employed. Electrical induction coils, represented schematically by heating coils CHC of FIG. 5, are wound inside the chamber and are supplied, in controlled fashion, with alternating electric current. This produces an alternating magnetic field in the path of the lasts, which, in turn, generates eddy currents in the lasts, to heat the same. In this way, moisture is driven out of footwear on the lasts, from the inside.

As an alternative to, or in addition to this method, the articles F may be pre-heated before entering chamber C. For this purpose, in accordance with this embodiment, they pass through a heat-setting chamber immediately prior to entering chamber C. This chamber is indicated at HC in FIG. 1 and is illustrated in more detail in FIG. 6. In this embodiment, chamber HC is of the form disclosed in U.K.Patent application Ser. No: 42909/67 filed Sept. 21 1967 in the name Automagique (Conveyors) Limited; it will therefore be only briefly described:

The chamber is open-ended having strip steel curtains 51 to inhibit heat loss from said ends. A partition divides the chamber horizontally below trackway 1. The lower part of the chamber includes heating coils 52, a fan 53 and a water trough 54. The air in the chamber is blown by the fan and passes over the heating coils and trough S4, picking up water from the latter, and being delivered into the upper part of the chamber through outlets 55. Air inlets 56 enable a circulation of hot, moisture-laden air to be produced in the chamber.

With the above-described arrangement, the articles F are treated in chamber HC immediately before passing into chamber C at a temperature of around C.

As mentioned above, the apparatus shown in the drawings may also be used for moisturizing the articles of footwear F. In this event, the plate 37 closing the third aperture (see above and FIG. in the chamber C is replaced by a spray nozzle arranged to introduce a fine spray of moisture into the chamber. This nozzle may be a single or multi-jet type and is connected to a spray device S indicated in chain lines in FIG. 5.

Device S comprises a pair of

cylinders

57, 58 each of which receives a piston, the pistons being connected by a common piston rod 59. Cylinder 57 is a hydraulic cylinder, whereas cylinder 58 is intended to receive a supply of water through a supply pipe 60. it will be noted that cylinder 57 is of larger diameter than cylinder 58. This produces a pressure magnification in cylinder 58, when the piston in cylinder 57 is operated.

in use, water is drawn into cylinder 58 through supply line 60. Cylinder 57 is then operated to force the water under high pressure from cylinder 58, through the nozzle and into chamber C.

Where the apparatus is used for moisturizing the articles of footwear, the articles are first introduced into the chamber and the doors 27 are closed. The pressure in the chamber is then reduced to around 22 to 28 inches of mercury by pump 35. Whilst the chamber is still at sub-atmospheric pressure, moisture is sprayed on to the articles as described above and atmospheric pressure is then restored by opening valve 34. The effect of this is to draw the moisture into the material of which the articles are made.

I claim:

1. Footwear treating apparatus comprising a conveyor system including a trackway; a plurality of carriers in said trackway; lasts on said carriers for carrying partly-finished shoes for treatment; drive means for intermittently driving the carriers around the trackway; a vacuum chamber through which the trackway passes; means for sealing said chamber in a pressure-tight manner to enclose a group of last-mounted shoes for treatment; means for heating the shoes and lasts; and pressure-reducing means for subjecting the shoes within the chamber to sub-atmospheric pressure to cause accelerated evaporation of liquid therefrom.

2. Apparatus according to claim 1 wherein said means for heating the shoes and lasts comprises induction heating means for heating the shoes and lasts while the shoes and lasts are at sub-atmospheric pressure.

3. Apparatus according to claim 1 wherein said heating means comprises pre-heating means for heating the shoes and lasts before entry into said vacuum chamber.

4. A method of treating footwear comprising mounting partly-finished shoes for treatment on lasts on carriers, conveying the carriers intermittently along a trackway and through a vacuum chamber, sealing said chamber to enclose a group of last-mounted partlyfinished shoes for treatment, heating the shoes and lasts, and subjecting the shoes within the chamber to sub-atmospheric pressure to cause accelerated evaporation of liquid therefrom.

5. A method of treating footwear comprising mounting partly-finished shoes for treatment on lasts on carriers, conveying the carriers intermittently along a trackway and through a vacuum chamber, heating the shoes and lasts prior to the entry thereof into said chamber, sealing said chamber to enclose a group of last-mounted partly-finished shoes for treatment, and subjecting the shoes within the chamber to sub-atmospheric pressure to cause accelerated evaporation of the liquid therefrom.

6. Apparatus according to claim 1, wherein the chamber is open-ended and doors operable by pneumatic cylinder and ram devices are provided to close the ends of the chamber in pressure-tight fashion at required times.

7. Apparatus according to claim 1, wherein the pressure reducing means comprise a vacuum pump including water extraction means, and wherein a pneumatically-operated valve is mounted in the wall of the chamber to connect the pump to the chamber at required times.

8. Apparatus according to claim 7, comprising a further pneumatically-operated valve mounted in the wall of the chamber and arranged to connect the interior of the latter to atmosphere at required times.

9. Apparatus according to claim 1, further comprising a water spray device connected to the chamber and arranged to spray water onto articles of footwear therein at required times, this device comprising a piston and cylinder unit arranged to be supplied with water; a spray nozzle in the wall of the chamber to which the cylinder of said unit is connected; and a pneumatically-operated piston and cylinder unit of larger diameter than said water cylinder, wherein the pistons of the two units are connected so that movement of the pneumatic piston in one direction causes water to be drawn into the water cylinder, and movement in the other direction causes the water in said cylinder to be delivered to the spray nozzle.

10. Apparatus according to claim 1, wherein the carrier drive means include a reciprocating saw-tooth drive band in the trackway, and wherein each carrier has a pivoted catch device on its underside for engagement by said band, the arrangement being such that the teeth on the drive band engage the catch devices in one direction of band reciprocation and drive the carriers, but pass idly across said devices in the other direction of strip reciprocation, the drive band being terminated adjacent the opposite ends of said chamber and the free ends thereof being connected by a link which avoids the chamber whilst maintaining a reciprocating drive connection between said ends.

11. Apparatus according to claim 1 further comprising means for transporting footwear into and from the chamber comprising a slide in the trackway at a location preceding the intake end of the chamber; carrierengaging catch means on the slide; and drive means for moving said slide into the chamber at required times through the open intake end thereof, the arrangement being such that, at this time, said catch means draw fresh carriers into the chamber and simultaneously eject therefrom carriers previously in the chamber the slide subsequently being withdrawn to leave said fresh carriers in the chamber.

12. Apparatus according to claim 1, wherein a heat setting chamber is provided in the conveyor system at a location immediately preceding the first-mentioned chamber, whereby footwear carried by said carriers can be subjected to a heat setting operation prior to entering said chamber.

Claims

4. A method of treating footwear comprising mounting partly-finished shoes for treatment on lasts on carriers, conveying the carriers intermittently along a trackway and through a vacuum chamber, sealing said chamber to enclose a group of last-mounted partly-finished shoes for treatment, heating the shoes and lasts, and subjecting the shoes within the chamber to sub-atmospheric pressure to cause accelerated evaporation of liquid therefrom.

11. Apparatus according to claim 1 further comprising means for transporting footwear into and from the chamber comprising a slide in the trackway at a location preceding the intake end of the chamber; carrier-engaging catch means on the slide; and drive means for moving said slide into the chamber at required times through the open intake end thereof, the arrangement being such that, at this time, said catch means draw fresh carriers into the chamber and simultaneously eject therefrom carriers previously in the chamber the slide subsequently being withdrawn to leave said fresh carriers in the chamber.