US2610287A - Inductively heated shoemaking apparatus - Google Patents

Description

Sept. 9, 1952 w. s. ROBSON 2,610,287

INDUCTIVELY HEATED SHOEMAKING APPARATUS Filed Feb. 26, 1949 2 SHEETSSHEET 1 In van zar wzmam Jelwyn Robson his flzffor'neg Sept. 9, 1952 w. s. RoBsoN 2,610,287

INDUCTIVELY HEATED SHOEMAKING APPARATUS Filed Feb. 26, 1949 2 SHEETSSHEET 2 I In van far William Selwg n P0278012 v5g: hjiirnqy Patented Sept. 9, 1952 INDUCTIVELY HEATED SHOEMAKING APPARATUS.

William. Selwyn. Robson, Leicest'er England, as-

signor to United Shoe Machinery Corporation, Flemington, N. J a corporation of New Jersey Application February 26, 1949, Serial No. 78,534 In Great Britain March .4, 1948 6' Claims. 1

This. invention relates. .to improvementsjin apparatus for the manufacture of shoes and more particularly to apparatus for. usein lasting shoes especially where the shoe. upper is. permanently secured. to the insole. by means of. an adhesive.

In. the. manufacture of certain shoes in which the. marginal portion of. an. upper,, around the toe. of a. shoe, is tobe secured. inJlastedrelat-ion to a. shoe bottom member (e. e. an, insole)v by means, of an adhesive, the upper on. a last may baconformed tothe shape ofthe last by the employment. of a lasting machine of the so-called bed-lasting. machine type. (for example, the typedisclosed in UnitedStatesLetters PatentNo. 2,097,567., granted November 2,1937 upon an application. of F. B. Keall) which operates. to wipe the-marginal portion of the. upper. aroundthe toe of the. shoe over. the edge of. an..insole-. on. the last-bottom, inwardly of the edge. of the insole. Thereafter this portion .is, secured. in place by means of adhesive previously applied between the portion: and the margin of theinsole.

In. some. cases ithas. been proposedto. hold the marginal portion of the. upper, at the toe, in lasted. relation to the. insole, while. the adhesive issetting, by means of a toe plate'or other temporary holding. means which is secured to the shoe. bottom. and, remains, on the shoe when the latter. is removed. from. the. lasting machine. After the. adhesive. has set, the temporary up.- per. holding means is removed from the shoe.

In order to speedup thesetting of the adhesive and. thereby render the. use of such temporary upper holding meansv unnecessary, ltihas been proposed that. a heated device, correspondingin outline tov the toe of a shoe, be placed by the operator. on the wiped over margin of the upper (the wipers. having been momentarily lifted away from .or. backed off from that margin to enable the device to be placed in position thereon). Pressure is then applied to the device. by meansof the wipers, and after a few seconds (the actual length of time. depending upon the temperature of the device. and the pressure applied) the. adhesive will? have. become sufliciently set" to permit the shoe to be removed from the lastin machine and subjected without .undue delay to the next manufacturing operation to be performed thereon.

A device which has been used for this purpose takes. the form of a small hand tool comprising a U-shaped plate-like member attached to a handle, the member being designed to be heated by placing it in a gas flame between lasting operations on consecutive shoes. The use of gas heated, tools has the disadvantage: of the production of undesirable fumes; and the naked flame constitutes an appreciable fire risk, especially when adhesive producing inflammable solvent vapors are employed. It has also been pro-- posed to use portable electrically heated tools for 2. this purpose, but such use has met little suecessin practice hitherto due to the fact that the electric elements do. not stand up to prolonged use under shoe factory conditions wherein the tools are subjected to severe jolts, tending quickly to disrupt the elements. Another disadvantage of such a tool is the necessity for the use of trail,- ing; supply leads. which tend. to. catch on pro.- iecting portions. of the machine and. generally get in. the operators way.

It is an object of the invention to provide an improved organization of apparatus. for accelcrating the setting of the toe lasting adhesive which does not suiier. from. the. above-mentioned disadvantages.

Another object. of the invention is to provide an improved transformer apparatus for inducing heating. currents, for example, in. portable tools comprising a closed conductive loop adapted to form the secondary of. a transformer, whereby such tools; may be. conveniently and efficiently heated.

Further objects. and advantages of the, inventionv will be apparent and the. invention itself willbe. best. understood withreference-to the following specification and the. accompanying drawings in which Fig, 1 is, an. angular view of an organization comprising a transformer apparatus and aportable. hand tool adapted. to be inductively heated for subsequent. use in. accelerating the setting of toe lasting adhesive in a bed-lasting, machine, said tool being shown positioned for. heating in said transformer apparatus;

Fig. 2. is an angular view. of the portable. tool shown in Fig. 1;

Fig. 3. is a side elevation of the transformer apparatusshown in Fig. 1; and

Fig; 4' is a diagram of the electric circuit in.- volved in. the transformer apparatus shown. in Fig. 1.

The hand tool shown in Fig. 2 is constructed tohave its heated portion form part of a closed conductive loop which is adapted to link the core of a transformer and form the secondary Wind'- ing thereof, whereby said portion is heated by hysteresis and the high current'induced. in the loop. The tool comprises a U-shaped plate-like member ll made of steel and conformed to the toe portion of a shoe bottom. Joining the ends of this member and connected thereto in a manner providing a minimum of resistance, asby welding, is a bridge member 13 of ametal of relatively greater conductivity than the plate-like member, for example; being conveniently made of copper. A short metal rod I-I- extends up- 'wardlyand rearwardly away from the bridge member I3 to which it is attached, and to this rod is secured'a wooden handle Hi.

The tool shown in Fig. 2 is adapted for use particularly with a machine of the type disclosed Because of the greater conductivity of the The primary coil 30 is adapted for connection by leads 6!) and 62 to a source of alternating current having a potential sufficient to attract the armature 36 into closing relation with the core 22. When a tool is not being heated, a resistance 65 is interposed between lead 60 and the coil. This resistance is sufiicient to reduce the potential of the alternating current supplied to bridge member and the conversely greater resistivity of the plate-like member ll, an induced current flowing through the closed loop comprising theconnected members II and l3 will produce a greater heating effect in the plate-like member I l than in the bridge member [3. Accordingly, that portion of the tool which is to be applied to the shoe bottom will be heated to a greater extent than that portion of the tool carrying the handle, resulting in a greater degree of efiiciency than if the conductive loop were of uniform conductivity. At the same time this arrangement tends to keep the handle relatively cool.

Apparatus for inducing a heating current in the tool is shown in Figs. 1 and 3. These figures illustrate certain features of the invention,

including the means by which the closed loop of the tool may be linked with a flux core to form the secondary of a transformer and yet be readily removable from said core for application to a shoe.

The apparatus comprises a base plate 20 upon which a U-shaped transformer core 22 is supported on brackets 24 and 26 with the limbs of the core vertically disposed, one limb near the front and one rearwardly thereof. The crossmember 23 of the core, corresponding to the base of the U, carries a winding 32 which forms the primary coil of the transformer apparatus. Attached to the two sides of the rear limb of the core and extending rearwardly and upwardly therefromare plates 32 between which an armature assembly 33 is pivoted on a pivot pin 34. The armature assembly comprises an armature 36 (effectively comprising a section of transformer core) supported between two parallel metal strips 38 by bolts 4,!) (Fig. 1), the strips 38 extending rearwardly beyond the armature where they are journaled on the pivot pin 34. Accordinglythe armature is movable into bridging relation with the ends of core 22 to provide a magnetic circuit of low reluctance. In another aspect, the core and armature together may be regarded as a substantially. rectangular transformer core having a portion movable into spaced relation with the remaining portion.

Normally, that is, while the apparatus is in use, except during the heating cycle, the armature is maintained in spaced relation with the remainder of the core by being urged upward and out of engagement with the upper faces of the limbs of core 22 by a spring 42 extending between a transverse pin 44 in the armature assembly 33 and a transverse pin 46 between the plates 32. The spring 42 surrounds a rod 48 which extends radially from the pin 44, passing through a bore extending diametrically through the pin 46. The upper end of the spring engages a collar 50 secured to the rod while the lower end of the spring engages a collar 52 slidable onrod 48. A stop collar 54 is secured to the rod 48 at its lower end.

the coil to a value at which the attraction between the ends ofcore 22 and the armature 36 is insufficient to overcome the force of the spring During the heating cycle, the resistance 64 is shunted by a mercury switch 66 extending forwardly and rearwardly of the apparatus and pivotally mounted adjacent to its rear end on a transverse pin 68 carried by side plate 12 forming the bracket which supports the front end of the core 22. A cross-piece 74 extends transversely between upper end portions of the side plates 12, and through a hole in this cross-piece a rod 76 extends downwardly to support the forward end of the mercury switch, the rod in turn being suported by a spring 18 extending between a collar 80 and the cross-piece M. The mercury switch is normally held in the tilted position shown in Fig. 3 so that it does not shunt out the resistance 84, but when a toll such as that illustrated in Fig. 2 is positioned in linking relation on the forward limb of core 22 through the space provided by the open armature, the weight of the tool resting on collar 80 depresses rod 16 to pivot the mercury switch to a more horizontal position in which it shunts out the resistance 64.

In this position, the energy supplied to the primary coil is sufficient to cause the armature 36 to move into engagement with the upper facesof the limbs of core 22. The armature remains in this closing relation with the core until the tool is lifted, whereupon spring 18 returns the mercury switch 66 to a tilted position, efiectively inserting the resistance 64 in series relation with the supply circuit. Thereupon the current in coil 3%] becomes insufficient to hold the armature in such closing relation. The small current which flows through the coil under these circumstances advantageously overcomes any remanent magnetism in the core which might tend to keep the armature attracted thereto. This small current insures that at some instant in the current cycle this magnetism is reduced to zero, any subsequent increase in the magnetic field during the flow of this small current being insufficient to cause the armature to be held in its closed position.

In the illustrative apparatus (Fig. l) the lower portion of the core, the lower part of the primary coil, the resistance and the switch are conveniently enclosed in a metal case having ventilating holes 92 in its walls, while the upper part of the coil is protected by means of. an asbestos bridge piece 94 extending between the limbs of the core, which bridge piece protects the windings of the coil from contact with the heating tool and from heat radiated therefrom.

In operation the operator finds the heating apparatus with its armature spaced from the core. Through the gap thereby provided, the tool, shown in Fig. 2, is positioned in linking relation with the forward limb of the transformer core. In this position, the tool rests as shown in Fig l, with its weight primarily supported upon the collar 80, causing the mercury switch to be closed and the armature to be attracted to a position in closing relation with the core, in which position a, path for the magnetic flux is provided which is substantially free from air gaps. Accordingly the tool is physically linked with the core and is inductively coupled to a maximum flux, the leakage flux being reduced to a minimum by the closing or" the core.

When the tool is heated, the operator may then grasp it by its handle, lifting it away from the collar 89 and allowing the mercury switch to be tilted to the off-position, whereupon the armature is released to be moved to a spaced relation with the core under the urging of the spring 42 so that the tool may be conveniently removed.

Although the invention has been described in connection with the illustrated apparatus, numerous variations Within the scope of the invention will occur to those skilled in the art and accordingly the claims are to be given a broad interpretation consistent therewith.

Having described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. In apparatus of the class described, a portable heating tool comprising a closed conductive loop and a handle, a transformer core having a fixed portion and a portion movable with respect to said fixed portion to provide space for admitting said tool into linking relation with said core, a coil on the fixed portion of said core, a spring for urging said movable portion into spaced relation with said fixed portion, and a switch operated by the positioning of the tool in a predetermined position in linked relation with said core for connecting said coil to a supply of alternating current sufficient to close said movable portion by magnetic attraction.

2. Apparatus for inducing heating current in a closed loop heating tool comprising a core forming an incomplete loop having spaced ends, a primary coil on said core, an armature pivoted for movement into and out of engagement with the ends of said core to bridge the gap therebetween, a spring for yieldingly urging said armature out of contact with the core, means for connecting said coil to a source of alternating current through a resistance sufficient to limit the current to an amount insufiicient to cause said armature to be attracted to said core against the force of the spring, and a switch arranged to be operated by the weight of such a tool for shunting out said resistance when the tool is resting in linked relation with said apparatus.

3. In apparatus of the class described, a portable hand tool in the form of a closed conductive loop having a handle attached thereto, a transformer core forming an incomplete loop having spaced ends and carrying a primary coil, an armature comprising a transformer core section movable into and out of bridging relation with said ends, a spring for yieldingly urging said armature out of said bridging relation, and means for connecting the coil to a source of alternating current comprising a switch adjacent to said core and adapted to be held closed by the weight of said tool while the tool is disposed in linked relation with the core during the heating cycle to supply alternating current to said coil sufiicient to attract said armature into said bridging relation, said switch being actuated by resilient means, upon the lifting of said tool, to effectively insert in circuit a, series resistance sufficient to reduce the supply of current to the coil to an amount sufficient to overcome any remanent magnetism but insufficient to hold said armature in closing relation with said core.

4. Inductive heating apparatus comprising a transformer core, a portion of said core being movable into spaced relation from the remaining portion of said core to provide a gap by which a closed loop tool may be linked with said core, means for maintaining said movable portion normally in spaced relation with said remaining portion, a primary coil on a portion of said core, and means responsive to the movement of said tool into a predetermined heating position for connecting said coil to a source of alternating current sufficient to attract said movable portion into a position in closing relation with said remaining portion, said connecting means being also responsive to movement of said tool away from said linked, heating position, preliminary to unlinking it with said loop, for reducing the supply of current to the coil before the movable portion of the core is moved into spaced relation with the remaining portion.

5. Inductive heating apparatus comprising a transformer core having an opening therein, an armature movable to close said opening, means for maintaining said armature normally in an open position, a primary coil on said core, means for supplying said coil with alternating current comprising a resistance in series relation with said coil and sufiicient to reduce the potential of the alternating current supplied to said coil to an amount insufiicient to hold said armature in its closing position, and a switch actuated by the positioning of a tool in linked relation with the magnetic circuit of said heating apparatus for shunting out said resistance.

6. Inductive heating apparatus comprising a transformer core, a portion of said core being movable into spaced relation from the remaining portion of said core to provide a gap by which a closed loop may be linked with said core, a primary coil on a portion of said core, means adapted to be actuated by the weight of a closedloop-tool, disposed in a predetermined position in linked relation with said core, for controlling the supply of alternating current to said coil, said supply of power being sufiicient to close said core when applied, and means yielding upon such application for maintaining said core portion normally in said spaced relation.

WILLIAM SELW YN ROBSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,128,731 Spencer Feb. 16, 1915 1,413,053 Onstad Apr. 18, 1922 1,609,182 Sederholm Nov. 30, 1926 1,610,041 Cope Dec. 7, 1926 1,615,018 Langdon-Davies et al. Jan. 18, 1927 1,645,029 Sunderland Oct. 11, 1927 1,919,660 Kamborian July 25, 1933 1,975,459 I-Iolslag Oct 2, 1934 2,097,567 Keall Nov. 2, 1937 2,108,670 Kamborian Feb. 15, 1938 2,315,159 Moore Mar. 30, 1943 2,321,704 Robson June 15, 1943 2,374,662 Black May 1, 1945 2,387,028 Kamborian Oct. 16, 1945 2,418,056 Strickland, Jr. Mar. 25, 1947 FOREIGN PATENTS Number Country Date 670,369 France Nov. 28, 1929

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