US2868420A - Apparatus for melting and dispensing thermoplastic adhesive - Google Patents

Description

' Jan. 13, 1959 T. A. WEISZ I APPARATUS FOR MEL-TING AND DISPENSING THERMOPLASTIC ADHESIVE 2 Sheets-Sheet 1 Filed out, 30, 1957 llam /mgr ez z WM .u I w fl w MVVA? 1 w m 1/ n E 4 2, \E z J y m: D 1m j THERMOPLASTIC ADHESIVE Filed Oct. 30, 1957 Jan. 13, 1959 "r. A. WEISZ 2,853,420

I 'APPARATUS FOR MELTING AND DISPENSING 2 Sheets-Sheet 2 Yzzi APPARATUS FOR MELHNG AND DISPENSING THERMQPLASTHC ADHESIVE Thomas A. Weisz, Plymouth, Mass, assignor to Jacob S. Karnhorian, West Newton, Mass.

Application October 3t), 1957, Serial No. 693,352

12 Claims. (Cl. 222394) This invention relates to a container for melting and dispensing adhesive, for example for supplying liquid thermoplastic adhesive to the applicator nozzle of a shoe or panel lasting machine or the like.

In the manufacture of covered panels with a machine of the kind shown in Patent No. 2,701,003 a flexible covering is adhered to one side of the panel with its margin projecting laterally therefrom and then the margin is stressed over the edge and adhesively secured to the other side. Just before the margin is laid down a quick-setting adhesive is injected into the angle between the margin of the panel and the covering. The adhesive is supplied through an applicator nozzle, by means of a pump associated with a container in which the adhesive is melted, and since the pump has a comparatively short stroke several strokes of the pump are required to supply enough adhesive to coat the entire marginal edge of a panel of ordinary size. Consequently, since the panel is traversed at a relatively fast rate during the interim between its strokes, that is, duty cycles the stream of adhesive dwindles and even stops so that there are areas which have insufficient adhesive or none at all. Consequently, in the finished panel the marginis not uniformly secured and may become loose.

The principal object of this invention is to provide means for supplying a continuous uniform ribbon of adhesive to the margin of the panel in contrast to the intermittent application referred to. Another object is to employ air pressure to attain a continuous and uninterrupted flow of adhesive throughout an entire working period without unduly exposing the melted body of adhesive to the oxidation of the air employed to produce the flow.

As herein illustrated the foregoing is attained by means of a closed pressure chamber to which melted adhesive is supplied when the pressure within the chamber is normal and from which adhesive is discharged by raising the pressure above normal. in accordance with the invention the pressure is increased in the pressure chamber to expel the adhesive by means of a tubular passage extending from the chamber which contains more than enough adhesive to coat the entire marginal edge of any panel expected to be covered. Displacement of the ad tates atent O hesive in the passage increases the pressure in the pressure chamber and discharges a corresponding amount of adhesive from the chamber. Displacement is effected by air pressure applied to an end of the passage, the latter being of small enough cross-section so that the amount of adhesive exposed to the air is relatively small. A removable liner is disposed in the passage so that as oxidation takes place over an extended period the liner may be removed and replaced with a clean liner. The pressure chamber is supplied with adhesive from one above it and this one in turn is supplied with adhesive through holes in the bottom of a top chamber, within which adhesive in solid form is adaptedto be placed for melting. The top chamber is designed to receive a block of solid adhesive and there is heating means incorpo- 2,868,420 Patented Jan. 13, 1959 rated in the lower part of the top chamber and the upper part of the subjacent intermediate chamber to effect melting of the solid adhesive from its bottom side, in such fashion that the unmelted solid adhesive at the top, excludes air from contact with the melted adhesive at the bottom. The melted adhesive at the bottom in turn excludes air from the intermediate and bottom chambers.

Discharge may be controlled by a valve means which opens in response to the increase in pressure within the pressure chamber or by use of a second passage corresponding to the first passage within which adhesive stands to a height corresponding to that in the first passage. A removable lining member of the character used in the first passage may also be employed in the second passage.

The invention will now be described in greater detail with reference to the accompanying drawings wherein:

Fig. 1 is a plan view looking down on top of the container;

Fig. 2 is an elevation as seen from one side of the container;

Fig. 3 is a horizontal section taken on the line 3-3 of Fig. 2;

Fig. 4 is an isometric View of an adhesive receptacle of the kind used with the container;

Fig. 5 is a vertical section to much larger scale taken on the line 5-5 of Fig. 1;

Fig. 6 is a vertical section taken on the line 6-6 of Fig. 1, showing an air valve for admitting air pressure to the container;

Fig. 7 is a perspective view of a portion of the upper end of the lining tube showing the flattened sides; and

Fig. 8 is a vertical section of a modified container.

The container as shown in Fig. 5 has vertically arranged top, intermediate and bottom chambers 10, 12 and 14. The chamber ltl is open at the top, is of substantially rectangular cross-section, has downwardly and inwardly sloping walls 16 and a horizontal bottom 18. A cover 20 is disposed over the open top and the bottom has in it a plurality of small openings or ports 22. Around each of the openings there is a raised boss 24. The upper surfaces of the several bosses lie in a substantially horizontal plane above the bottom and provide a support spaced from the bottom. The chamber 10, as thus constructed, is adapted to receive for melting adhesive contained in solid form in a correspondingly shaped thin walled expendable receptacle 26 which contains a block of solid thermoplastic adhesivezd. The bottom of the receptacle 26 is designed to be perforated to allow adhesive to drain therefrom when melted within the receptacle. When placed in the container the receptacle rests on the boss 24 above the bottom.

The intermediate chamber 12 is of substantially rectangular cross-section, its top being constituted by the bottom 18 of the chamber 10. There is a threaded opening 32 in one wall of the chamber 12 into which may be screwed a thermostat 34. Heating elements, not shown, may be embedded in the walls of the chambers 12 and 14 and the heat developed by these heating elements, under the control of the thermostat, sutfioes to melt the adhesive in the receptacle 26'resting in the chamber i at the bottom so that it fiows through the perforations therein and through the opening 22 into the chamber 12' where it is kept melted, free from the oxidizing effect of air. The chamber 12 has a bottom wall 36 and in this wall 36 there is a plurality of openings or ports 38, in. each of which there is secured the cage 40 of a check valve assembly.

The bottom chamber M which is subjacent the intermediate chamber 12, has at its top the bottom wall 36 of the chamber 12, and provides a closed pressure chamher. This chamber is of substantially rectangular crosssection and has integral with one side wall a downwardly inclined tapering protrusion 42 in which there is a discharge passage 44 containing a normally closed check.

extends downwardly into it and each contains a ball 52 which normally rests on a pin 54 at the bottom of the cage but which may be lifted by an increase of pressure within the chamber so as to block the openings into the chamber 12. Each cage has in its wall above the ball narrow ports 56. I

In another side wall of the chamber 14 there is a lateral opening 58 and extending upwardly therefrom there is a vertical passage 60 which terminates at the same level as the top of the chamber 10.

The chambers N and 12 are cast in one piece, and the chamber 14 is likewise cast in one piece. The wall 36 is a separate piece which may be a casting or machined from a fiat piece of suitable gauge. The castings are assembled with the plate therebetween whereupon the several parts are screwed or otherwise secured together. In making the castings a portion of one of the side walls of each is made thicker and these thickened portions are cored so as to provide a passage of circular cross-section therethrough. When the castings are assembled with the plate 36 between them the respective passages form the vertically disposed passage 60 which extends from near the bottom of the chamber 14 upwardly to the top or" the chamber 10. The plate 36 is, of course, provided with an opening 64 which registers with the adjacent ends of the passages in the respective casting. That part of the passage in the casting making up the chambers 15 and 12 is carefully drilled so as to be of uniform diameter throughout its length.

At the top of the chamber 10 there is a cap 66 which is adapted to fit over the open end of the passage and to be hermetically clamped to it by means of a pair of screw bolts ss ss which extend through diametrical slots 7d7il in the cap and are threaded into bosses 72 72 on the casting. To make the seal air tight a gasket '74 is placed between the cap and the top of the passage, for example in a groove in the lower side of the cap. The cap has a threaded opening "75 into which is screwed an elbow 5 8 by means of which the passage is connected to an air valve 2%, which may be suitably operated to supply air to the passage.

Normally the liquid adhesive stands in the vertical passage at the same level as the adhesive in the chamber 1% and the air has contact with only the small area of liquid adhesive at the top of the passage. When the air valve is tripped to admit air pressure to the upper end of the standing column of adhesive the latter is forced downwardly thereby increasing the pressure within the chamber 14- which closes the ball valves 52, opens the valve 46 and forces adhesive through the pipe to its place of delivery. When the air valve is closed the pressure is relieved, the discharge valve is closed, the ball valves drop down and more adhesive is allowed to flow into the chamber ft-i from the chamber 12 and consequently into the chamber 12 from the chamber 19. Since the liquid adhesive in the chamber 1% is sealed from air by the solid block of adhesive above it and the liquid. adhesive in the chamber 123 is sealed by the liquid adhesive in the chamber 1% above it, the only contact that air has with liquid adhesive is in the vertical column of adhesive in the vertical passage. Since, as pointed out, the top end of the column is comparatively small there is little damage through oxidation. The volume of the vertical passage is designed to hold enough adhesive so that displacement of less than the entire amount of adhesive in it will operate on the adhesive in the pressure chamber to eject from the chamber more than enough adhesive to apply adhesive to the entire margin of the work. Preferably the volume is enough greater than the need so that the level of the adhesive in the passage as will not fall below the opening in the plate 36, so that there is no possibility of air gaining access to the chamber 14.

There is, of course, bound to be some oxidation of the adhesive along the wall of the vertical passage as the air forces the columndown within it and then allows it to returnand then again forces it down so that there is a gradual accumulation of a small amount of oxidized adhesive built up within the passage which ultimately clogs it up. To minimize this possibility a thin wall sleeve 82 is slidably mounted in the passage with its lower end abutting the top of the plate 36 around the opening therein and its upper end 84 projecting above,

the top of the passage into the cap 66. The cap has a recess 86 for receiving the upper end of the tube so that there is an air tight seal between it and the gasket 74. When the oxidized adhesive accumulates within the tube so much as to interfere with efiicient operation of the apparatus the cap 66 is removed and the tube is pulled out of the passage and thrown away and a new one substituted in its place. Alternatively, the tube may be reamed out and reused. The tube may be made of any suitable substance, for example a thin walled aluminum tube has been found to be satisfactory and economical. Preferably the upper end of the tube is flattened on two sides so that a pair of pliers may be used for grasping 66 is applied air is trapped in the space between the tube and passage which blocks the adhesive from seeping upwardly between the outer wall of the tube and the inner Wall of the passage.

In Fig. 8 there is shown a modification of the container in which the discharge nozzle 42, passage 44 and valve 46 is dispensed with and a discharge passage 88 substituted therefor. Conveniently the passage 88 may be made in the same fashion as the passage 60 so that the component parts of the container may be made symmetrical. lining tube 919 and a cap 92 may be applied to the upper end of the passage over the protruding end of the lining tube and provides means for connecting a conductor 94 thereto, through which the adhesive may be carried to a suitable applicator. As thus constructed adhesive will stand in the passage 88 at the level of its upper end or as high as the level of the adhesive in the chamber id and this standing column of adhesive will act as a seal at normal pressures to prevent access of air through the passage into the chamber 14. When the pressure within the passage 60 is increased as previously explained, to displace adhesive from the chamber 14 a column of adhesive in the passage 38 will be displaced out of its upper end which corresponds in amount to that which is displaced downwardly in the passage 60.

It should be understood that the present disclosure is for the purpose of illustration only and that this invention includes all modifications and equivalents which fall within the scope of the appended claims.

I claim:

1. A container for dispensing adhesive comprising a closed pressure chamber, a discharge passage normally closed when the pressure within the chamber is normal, through which adhesive may be discharged by an incr ase in pressure within the chamber, means for increasingthe pressure within the chamber to discharge adhesive frorn the chamber including a tube for holding a volume of adhesive at least equal to the volume expected; to be The passage may be lined with a removable.

tubebeing of comparatively small cross-section and in communication at one end with the chamber, the opposite end of the tube being adapted to be connected to a source of air pressure by means of which adhesive in the tube may be displaced to increase the pressure within the chamber and to discharge adhesive therefrom in an amount corresponding to the amount displaced in the tube, and means for supplying adhesive to the chamber When the pressure within the chamber is normal.

2. A container for dispensing adhesive comprising a closed pressure chamber, a discharge passage, a normally closed valve for, controlling the flow of adhesive through the discharge passage, through which adhesive may be discharged by an increase in pressure in the chamber, means for increasing the pressure within the chamber to discharge adhesive therefrom including a tube for holding a volume of adhesive at least equal to the volume expected to be discharged from the chamber at any given time, said tube being of comparatively small cross-section and in communication at one end with the chamber, the opposite end of the tube being adapted to be connected to a source of air pressure by means of which adhesive in the tube may be displaced to increase the pressure within the chamber and to discharge adhesive therefrom in an amount corresponding to the amount displaced in the tube, and means for supplying adhesive to the chamber when the pressure within the chamber is normal.

3. A container for dispensing adhesive comprising a closed pressure chamber, a discharge passage near the bottom of the chamber, a check valve in the passage for controlling. the flow of adhesive therethrough, said check valve being normally closed when the pressure within the chamber is normal but being opened by an increase in pressure therein, means for increasing the pressure within the chamber to discharge adhesive therefrom including a tube for holding a volume of adhesive at least equal to the volume expected to be discharged in 4. A container for dispensing adhesive comprising a closed pressure chamber, a discharge passage normally closed when the pressure within the chamber is normal, through which adhesive may be discharged by an increase in pressure within the chamber, means for increasing the pressure Within the chamber to discharge adhesive from the chamber including a tube for holding a volume of adhesive at least equal to the volume expected to be discharged from the chamber at any given time, said tube being of comparatively small cross-section and in communication at one end with the chamber, the opposite end of the tube being adapted to be connected to a source of air pressure by means of which the adhesive in the tube may be displaced to increase the pressure within the chamber and to discharge adhesive therefrom in an amount corresponding to the amount displaced in the tube, a supply chamber situated above the pressure chamber containing liquid adhesive and normally open valve means connecting the supply chamber with the pressure chamber, so that liquid adhesive gravitates from the supply chamber into the pressure chamber when the pressure within the pressure chamber is normal, said valve means being closed by an increase in pressure within the pressure chamber.

5. A container for dispensing adhesive comprising a pressure chamber, a discharge passage normally closed when the pressure within the chamber is normal, through which adhesive may be discharged by an increase in pressure within the chamber, means for increasing the pressure within the chamber to discharge adhesive from the chamber including a tube for holding a volume of adhesive at least equal to the volume expected to be discharged from the chamber at any given time, said tube being of comparatively small cross-section and in communication at one end with the chamber, the opposite end of the tube being adapted to be connected to a source of air pressure by means of which adhesive in the tube may be displaced to increase the pressure within the chamber and to discharge adhesive therefrom in an amount corresponding to the amount displaced in the tube, a supply chamber situated above the pressure chamber, normally open valve means connecting the supply chamber and the pressure chamber when the pressure within the pressure chamber is normal so that adhesive in the supply chamber gravitates into the pressure chamber, said valve being closed by an increase in pressure in the pressure chamber, an adhesive melting chamber situated above the supply chamber within which solid adhesive may be melted, and open ports connecting the melting chamber with the supply chamber.

6. A container having vertically arranged top, intermediate and bottom chambers, the bottom of the top chamber constituting the top of the intermediate chamber and the bottom of the intermediate chamber constituting the top of the bottom chamber, a plurality of openings in the bottom of the top chamber, opening into the intermediate chamber, through which adhesive deposited in the top chamber in solid form and melted therein gravitates into the intermediate chamber, said intermediate chamber being isolated from the ambient air by the presence of a body of liquid adhesive in the top chamber, valve means in the bottom of the intermediate chamber opening into the bottom chamber, said valve means being normally held open by gravity and being closed by an increase in pressure in the bottom chamber, a discharge port in the bottom chamber containing valve means which normally is held closed so as to prevent escape of adhesive from the bottom chamber, means for increasing the pressure in the bottom chamber to force the adhesive therefrom through the discharge port comprising a vertical passage containing at least as much adhesive as is expected to be discharged from the chamber at any one time, said passage being of comparatively small crosssectional area, connected at its lower end to the bottom chamber and rising to the level of the top of the top chamber and in which adhesive stands at the level of the upper end, and means for applying pressure to the top surface of the column of adhesive standing in the passage to displace a part of the adhesive downwardly therein and hence to increase the pressure within the bottom chamber and to displace a corresponding quantity of adhesive through the discharge port in the bottorn chamber without lowering of the column of adhesive standing in the vertical passage below the opening at the junction of the passage with the bottom chamber.

7. A container according to claim 1, wherein there is a removable tubular lining within the tubular passage at least as long as the distance'the adhesive will be displaced in the passage.

8. A container according to claim 1, wherein there is a removable lining tube slidably disposed in the tubular passage with an end extending from the passage far enough to be grasped to facilitate removal, and the means connected to the end of the passage for supplying air pressure to the column of adhesive in the tube comprises a cap fitted over the end of the lining, means hermetically clamping the cap over the end of the passage and a conduit connected to the cap through which air pressure may be supplied to the passage.

9. A container according to claim 1, wherein there aseaeao T. is aremovablelining tube slidably disposed in the ,passage withan end of it extending beyond .the passage, the projecting end of the lining having on its outer wall flattened surfaces to facilitate grasping said end.

10. A container for dispensing adhesive comprising a closed pressure chamber adapted to hold a quantity of melted adhesive, a tubular discharge. passage connected at its lower end to the chamber and extending upwardly therefrom to a level exceeding the height at least at which the adhesive will stand in the chamber, means for increasing the pressure in the chamber to discharge adhesive therefrom through the discharge passage including a second tubular passage connected at its lower end to the chamber and extending upwardly therefrom to a level corresponding to that of the first tube, meansat,

the upper end of the second tubefor connecting it to a, v

11. A container according to claim 10, wherein there is a tubular lining in the first passage extending from near the bottom of the passage to the top thereof.

1 2 A'container for dispensing adhesive according to claim 10, in whichthere is a tubular lining in each of the tubular passages which extends from near the bottom to near the top thereof, said linings being removable.

No references cited.

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