ADHESIVE APPLICATOR, AND MACHINE FOR APPLYING ADHESIVE

Abstract: A machine for applying adhesive to a surface (6) of a workpiece comprises a support table (8) to support a workpiece, conveniently horizontally, and a gantry (13) mounted over the support table. Mounted on a horizontal arm (16) of the gantry is a carriage (18), which supports an adhesive applicator (28). The applicator comprises a body (30) which is fixed to the carriage (18), and an applicator head (40) mounted for rotation on the body. The body comprises first and second inlets (32, 34) adapted to be connected to supplies of constituents of an adhesive composition, and passages (33, 35) extending from the inlets through the body. The head (40) carries one or more outlet nozzles (60), said head (40) being rotated about a drive axis by a motor (72) carried by the carriage (18). The head is provided with one or more first passages (50<u>a</u>, 50<u></u>) which are in communication with the first passage (33) in the body, and one or more second passages (52<u>a</u>, 52<u>a</u>) in communication with the second passage (35) in the body. Thus, as the head is rotated adhesive flows through the passages in the body and in the head, to be mixed in the outlet nozzles, and dispensed therefrom whilst the head rotates. During use of the machine, adhesive is thus dispensed from the applicator whilst the carriage is traversed back and forth along the gantry arm (16) under computer control, whilst the gantry moves lengthwise of the workpiece in the longitudinal direction.

Description: Title: Adhesive applicator, and machine for applying adhesive Description of Invention This invention is concerned with improvements relating to the application of adhesive, in particular to the application of adhesive to a substrate. In a number of manufacturing or assembly processes, it is necessary to apply adhesive to a substrate over an extensive area thereof, to enable the substrate to be bonded to another component. For example, in the building industry a frequently-used component comprises a metal panel to which an insulated sheet of foam plastics, such as polyurethane, is bonded. Additionally, frequently utilised is extruded polystyrene sheet, bonded adhesively to timber or plasterboard panels. Further, in the manufacture of furniture, M.D.F. (Medium Density Fibreboard) is more and more widely used, and this requires an outer skin, which may be of wood or plastics sheet, to be bonded to a substrate comprising a panel of compressed fibreboard. Difficulty is encountered in applying adhesive to substrates of this kind, particularly where a controlled quantity of adhesive is to be applied to the substrate over an extensive area thereof. One conventional method of applying adhesive to a substrate involves the use of an adhesive dissolved in a solvent which is sprayed onto the surface of the substrate. However, not only is this wasteful, in that it is difficult to effect control over the area to which the adhesive is applied, but also such a process may be harmful to the health of operatives, and generally ecologically disadvantageous. Additionally, in most applications it is in general not necessary to apply adhesive over the whole of the area of the substrate, and to improve efficiency of utilisation of the adhesive, it is acceptable to apply the adhesive to part only of the area. Thus another conventional method involves the use of an applicator head comprising a plurality (eg. 24) nozzles from which narrow ribbons or beads, hereinafter referred to as ribbons for convenience, of adhesive are extruded as the applicator passes over the substrate. A major difficulty which is encountered is that it is not possible, by measuring increases in the back pressure, to determine when, during operation, one or more nozzles become blocked, and in general such a malfunction can remain undetected for some time with possibly deleterious consequences to the production run. Additionally, applying adhesive in the form of ribbons is not the most efficient way of applying adhesive to the substrate. Consequently it is one of the various objects of this invention to provide an adhesive applicator for applying adhesive to a substrate, in which some at least of the problems encountered in conventional systems are overcome. According to this invention there is provided an applicator comprising: a) a body having an inlet to which a supply of adhesive, or an adhesive component, may be connected, the body having passage means extending from the inlet; b) a head mounted on the body for rotary movement relative thereto; c) means to rotate the head relative to the body; and d) passage means in the head extending to a nozzle earned by the head and which is in communication with the passage means of the body as the nozzle is rotated. Preferably the nozzle is operatively spaced from the axis of rotation of the head, whereby during rotation of the head the nozzle traces a circular path relative to the head. Thus the nozzle may be aligned parallel to the axis of rotation, spaced laterally therefrom, or the nozzle may be located on the axis about which the head rotates, but may be inclined to such axis, such as inclined outwardly from the axis. Alternatively, the nozzle may be located a short distance from the axis of rotation of the head, and be inclined to the axis about which the head rotates. If desired the nozzle may be mounted for articulative movement relative to the axis of rotation of the head, such as under computer control. The passage means of the head may be in communication with the passage means of the body intermittently during rotation of the head whereby as the head is rotated adhesive is dispensed intermittently, eg. in the form of short pulses. Preferably however the passage means are in communication continuously, whereby as the head is rotated adhesive is dispensed in a substantially continuous stream. If desired the passage means in the head may extend to a plurality of nozzles whereby during operation of the applicator adhesive is dispensed in a plurality of streams simultaneously. Thus preferably the head comprises more than one nozzle, preferably no more than ten. Preferably the applicator comprises valve means operative to open the passage means in the body to the supply of adhesive, preferably the supply of adhesive being under pressure, and which may be operated speedily to close the passage means, and shut off the delivery of adhesive to the body, as may be desired. Preferably the applicator comprises sensing means operative to detect an increase in the pressure within the applicator, as may occur when a nozzle becomes blocked, and which is effective to cause the valve means to close the supply of adhesive to the applicator. Whilst the applicator set out above may be used to supply an adhesive constituent based on a single component, it is desirable, particularly in manufacturing or assembly processes where it is necessary to apply adhesive to a substrate over an extensive area thereof, to use an adhesive comprising two components which are mixed together to form the adhesive composition. Heretofore however no applicator has been provided which adequately solves the problem of retaining the components separate in the applicator whilst ensuring adequate mixing of the two components immediately prior to application to the substrate, and it is a further object of this invention to provide an applicator which enables a two-part adhesive system to be applied to a substrate. Thus preferably the body of an applicator of the kind set out in the last preceding paragraph but nine comprises two inlets to each of which a supply of adhesive component may be connected, the body comprising first and second passage means extending from the respective inlets, the head comprising first and second passage means extending to the nozzle and which are in communication with the first and second passage means in the head, respectively, as the head is rotated. Similarly, where the adhesive comprises three components, the body preferably comprises three inlets to each of which a supply of one of the components may be connected, the body comprising first, second and third passage means extending from the respective inlets, the head comprising first, second and third passage means extending to the nozzle and which are in communication with the first, second and third passage means in the head, respectively, as the head is rotated. If desired, the applicator may similarly be adapted to handle adhesive compositions comprising more than three components. Thus in the operation of the applicator a first constituent (eg. where the adhesive is polyurethane, a polyol) may be connected to the first inlet, whilst a second constituent (eg. an isocyanate) may be connected to the second inlet. The head is caused to rotate, and by operation of the valve means the constituents are caused to flow under pressure from their respective inlets along their respective passages in the body, along their respective passages in the head to the nozzle, into which the two components flow and from which the mixed components are dispensed. Preferably the nozzle is of the kind known as a static mixing nozzle, having separate inlets for the two components, to which the passage means in the head extend. As the two components pass through the inlets of the nozzle, they are brought together and constrained to undergo a mixing motion, ensuring adequate mixing as they pass through and flow from the nozzle. Difficulty is further encountered in applying adhesive to a substrate in a manner which lends itself to automatic control, and in accordance with a further aspect of this invention there is provided a machine for applying adhesive to a workpiece comprising: a) means for supporting a workpiece in a plane; b) a gantry upon which an adhesive applicator is mounted for movement in a first direction parallel to the plane of the supporting means, said applicator comprising at least one nozzle from which adhesive may be dispensed against a workpiece supported by the supporting means, the gantry being mounted for movement relative to the supporting means in a second direction at right angles to said first direction and parallel to the plane of the supporting means; characterised in that adhesive applicator comprises a body having an inlet to which a supply of adhesive or a supply of an adhesive component may be connected, and a head mounted on the body for rotary movement relative thereto, passages being provided which extend from the inlet through the body and through the head to said nozzle which passages during rotation of the head relative to the body are in communication for some at least of the time during each complete rotation of the head. Preferably the applicator is of the kind set out in the last preceding paragraphs, and wherein said axis extends at right angles to said first and second directions. If desired, the supporting means may be afforded by a conveyor to move the workpiece in said second direction whilst supporting the workpiece, but preferably the gantry is moveable relative to the supporting means in said second direction. Preferably where the applicator comprises a plurality of nozzles, means is provided which is operative periodically to terminate rotation of the head and preferably also to rotate the head through an angle of 90° or an integral multiple thereof. Thus particularly whilst the applicator is being caused to traverse the gantry in said first direction, rotation of the nozzles may momentarily be ceased and the head rotated through 90° or an integral multiple thereof to improve the application of an appropriate quantity of adhesive at the corner of the surface of the workpiece. There will now be given a detailed description, to be read with reference to the accompanying drawings, of two adhesive applicators, and a machine for applying adhesive to a workpiece, which are preferred embodiments of this invention, having been selected for the purposes of illustrating the invention by way of example. In the accompanying drawings :- FIGURE 1 is a plan view of the machine which is the preferred embodiment of this invention; FIGURE 2 is an end elevation thereof taken in the direction of the arrow X of Figure 1; FIGURE 3 is a side elevational view of the adhesive applicator which is the first embodiment of this invention; FIGURE 4 is a view showing an alternative applicator head; FIGURES 5 and 6 are views illustrating patterns of application of adhesive applied to a substrate by the use of the machine; and FIGURE 7 is a sectional view of the adhesive applicator which is the second embodiment of this invention. The machine which is the preferred embodiment of this invention is for applying adhesive to a surface 6 of a workpiece 7, which may be in the form of a sheet of timber, or plastics material, and comprises a support table 8 to support the workpiece, conveniently horizontally. The machine comprises a gantry 13 mounted over the support table 8, and which is moveable relative to the table in a first direction A-A under the control of a computer console 12. The gantry comprises side supports 14a, 14b, and a horizontal gantry arm 16 extending between the supports 14, on which a carriage 18 is mounted for sliding movement in a second direction B-B, extending in a plane parallel to the plane of the support table and lying at right angles to the direction A. The carriage 18 supports an adhesive applicator 28 comprising a body 30 which is fixed relative to the carriage 18, and an applicator head 40 mounted for rotation on the body 30 about an axis C-C (see Figure 4). The body comprises first and second inlets 32, 34 adapted to be connected to supplies of constituents of an adhesive composition, and a control valve 36 adapted, by the use of a single control member 38, to open and close the inlets 32 and 34 simultaneously. The first inlet 32 extends to a first passage 33 which extends through the body, whilst the second inlet 34 extends to a second passage 35. The head 40 is mounted on the body 36, and carries one or more outlet nozzles 60. A drive motor 72 carried by the carriage 18 drives a gear wheel 74 which interacts with a gear wheel 42 of the body, to cause the body to rotate about said axis C-C. The first passage 33 comprises a short transverse section 33a which extends to a first annular channel 44 provided on the interior cylindrical surface of the head 40, whilst the second passage 35 comprises a short transverse section 35a which extends to a second annular channel 46, also provided in the interior cylindrical wall of the head 40. Each outlet nozzle 60 is located in a bore 48 of the head 40, and for each bore the head is provided with a first passage 50a, 50b and 50c extending from the annular channel 44 to the bore 48, and a second passage 52a, 52b, 52c extending from the second annular channel 46 to the bore 48 > (see Figure 4). The passages 50 and 52 extend into the bore 48 in such a manner that when the nozzle 60 is inserted into the bore, the first passage 50 extends to a radially outer part of the valve 60, whilst the second passage 52 extends to an axial part of the valve. In this manner it is ensured that first and second components passing through the head 40 do not come into contact until they pass into the nozzle. Thus during operation of the applicator, as first and second constituent components are fed through the inlets 32 and 34, and whilst the head 40 rotates about the axis C-C, said first and second constituent components are fed through the first and second passages 33, 35 respectively, and into the first and second annular channels 44, 46. From there the first adhesive constituent flows through the three passages 50a, 50b, 50c, whilst the second constituent flows through the three passages 52a, 52b, 52c, to be fed to the outlet nozzles 60, to be mixed therein and to be dispensed therefrom whilst the head 40 rotates. During use of the machine, the carriage 18 is traversed back and forth along the gantry arm 16 under the control of the control console 12, whilst the gantry moves lengthwise of the workpiece 6 in the longitudinal direction. The machine may be operated in various modes under the computer control. For example, the machine may be operated with the gantry stationary, whilst the carriage undergoes a complete traverse of the support table 8, whereupon the control valve 36 is operated momentarily to close the inlets 32, 34 whilst the gantry moves in the direction A across the workpiece 10 by one step, prior to movement of the carriage 18 in the opposite direction across the workpiece 6. In this manner a pattern of adhesive is applied to the surface of the workpiece from each outlet nozzle 60 which is in the form of a spiral pattern (although of course being two dimensions) providing a highly economic distribution of adhesive on the surface of the workpiece. Alternatively the carriage may be maintained stationary whilst the head 40 rotates, with adhesive being dispensed from the nozzles 60, whilst the gantry 8 moves the full length of the workpiece, whereupon the carriage is indexed a short distance along the gantry arm prior to movement of the gantry in the opposite direction. If desired, the control device may be operative momentarily to cease rotation of the head, particularly whilst adhesive is being dispensed in the corner regions of the workpiece, allowing the nozzles to take adhesive into the corner of the workpiece. Preferably during this operation the control device may operate to rotate the head through 90° (or 270°) to ensure a full application of adhesive in the corner regions, prior to re-commencement of continuous rotation. It will be appreciated that the volume of adhesive applied to the workpiece is dependant upon the speed of operation of the conveyor 8, and the speed of traverse of the carriage 18 along the gantry arm, and a heavier application of adhesive may be applied by reducing these speeds. Additionally, a wider band of adhesive may be applied to the workpiece during each pass, by increasing the rotational speed of the head 40, causing adhesive to be thrown radially outwardly. There is shown in Figure 5 a typical distribution pattern of adhesive on the surface of a substrate, as the applicator passes over the workpiece. It will be appreciated that the quantity of adhesive delivered per unit area of the substrate may be controlled relatively easily, either by varying the speed of rotation of the applicator, together with the speed of traverse of the workpiece by the applicator, and by variation of the pressure at which the constituents of the adhesive are applied to the applicator. Thus, whilst the pattern shown in Figure 5 illustrates a combination of parameters which involve deposition of continuous ribbons of adhesive onto the substrate, in Figure 6 there is shown an application pattern, in which the lines of adhesive applied to the substrate have been broken into discreet globules, this being obtained by a higher rotational rate of the applicator and/or a wider dispersal angle of the applicator nozzle. Thus by judicious tuning of the various parameters, any one of a large number of application patterns may be obtained on a substrate. Desirably the applicator comprises sensing means (not shown) to sense the back pressure of the adhesive constituents during operation of the machine, and which is operative on sensing an increase in back pressure, as may indicate a blockage in one of the outlet valves, to send a signal to the control device to cause (for example) the control device to shut down operation of the machine, and/or to activate an alarm signal. Since the two components do not come together other than within the outlet nozzles, on completion of operation of the machine the first and second constituents may simply be purged, such as by the use of feeding air through the inlets 32 and 34, and replacing the outlet nozzles 60 as necessary. Conveniently the outlet nozzles are of the static-mixing type, comprising separate inlets for the two components and providing, interiorally thereof, with blades or vanes to cause mixing movement of the constituent materials as they flow through the outlet nozzle, to cause mixing thereof prior to exiting the nozzle. It will be appreciated that whilst the invention has been described above, particularly in relation to the first embodiment, in the use of a rotary head for dispensing an adhesive composition produced by the mixing together of two constituents, the principles of the invention may be utilised with advantage where a single adhesive compound is used. This may be accomplished in the case of the preferred embodiment, by connecting such an adhesive compound to one only (eg. the first) inlet, leaving the second inlet blank, or maybe put into practice by an applicator which differs from the preferred embodiment, insofar as it is provided with a single passage means extending through the body, and a single passage means extending through the head for each of the outlet nozzles. Additionally, the invention may be utilised in relation to the dispensing of an adhesive composition produced by the mixing together of three (or more) components, wherein the body comprises inlets for each component, to each of which a supply of one of the components may be connected, to body comprising passage means for each component extending from the respective inlets, the head comprising passage means extending to the (or each) nozzle for each component, and which are in communication with the respective passage means in the head, as the head is rotated. Alternatively, the applicator may be mounted on the end of a robotic arm, drive means from which causes rotation of the head. Whilst in the prefeπed embodiment a dispensing head has been shown which comprises three outlets nozzles 60a, 60b, 60c, it will of course be appreciated that the invention may be utilised with a single outlet nozzle, or with a number of outlet nozzles greater than three. The adhesive applicator which is the second embodiment of this invention, shown in Figure 7, is generally similar to the first embodiment, and similar numerals, although increased by 100, been utilised to identify similar or corresponding parts. The applicator comprises a body 130 which is fixed relative the carriage 118, and an applicator head 140 is mounted on the body 130 for rotation about the axis C. The body comprises inlets 132, 134 adapted to be connected to supplies of constituents of the adhesive composition, and a control valve 136 adapted, by the use of a single control member, to open and close the inlets 132 and 134 simultaneously. The first inlet 132 extends to a first passage 133 which extends through the body, whilst the second inlet 134 extends to a second passage 135. The body 149 is rotatable about the axis C by a servo-motor 172 through the intermediary of a drive coupling 173, similarly under computer control. The head is provided with a first passage 150a extending from an annular channel 144 which is in communication with the first passageway 133, and a second passage 152a which extends from a second annular channel 146 which is in communication with the passage 135. The passages 150a and 152a are in communication with an outlet nozzle 160, which is inclined to the axis C, whereby as the head 140 is rotated, adhesive is dispensed from the nozzle 160 along a circular path, in a manner similar to that executed by the first embodiment. The manner of use of the applicator which is the second embodiment of this invention, as part of an adhesive applying machine, is similar to the first embodiment above described, to which reference should be made. The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims: CLAIMS 1 An applicator (28) comprising: a) a body (30) having an inlet (32, 34) to which a supply of adhesive may be connected, the body having passage means (33, 35) extending from the inlet (32, 34); b) a head (40) mounted on the body (30) for rotary movement relative thereto; c) means (72) to rotate the head (40) relative to the body(30); and d) passage means (50, 52) in the head (40) extending to a nozzle (60) carried by the head (40), and said passage means (50, 52) being in communication with the passage means (33, 35) of the body as the head (40) is rotated. 2 An applicator according to claim 1 wherein the nozzle (60) is operatively spaced from the axis C-C of rotation of the head (40). 3 An applicator according to claim 1 wherein the nozzle (60) is aligned parallel with the axis C-C about which the head (40) rotates. 4 An applicator according to claim 1 wherein the nozzle (60) is inclined to the axis C-C about which the head (40) rotates. 5 An applicator according to claim 1 wherein the nozzle (60) is mounted for arti dilative movement relative to the axis C-C of rotation of the head. 6 An applicator according to any one of the preceding claims wherein the passage means (33, 35) of the head is in communication with the passage means (50, 52) of the body (30) continuously during rotation of the head (30). 7 An applicator according to any one of the preceding claims wherein the passage means (50a, 50b, 50c, 52a, 52b, 52c) in the head extends to a plurality of nozzles (60a, 60b, 60c). 8 An applicator according to any one of the preceding claims comprising valve means (36) operative to open the passage means (32, 34) in the head (30) to the supply of adhesive, and which may be operated speedily to close the passage means. 9 An applicator according to any one of the preceding claims comprising sensing means operative to detect an increase in the pressure within the applicator to cause the valve means to close the supply of adhesive to the applicator. 10 An applicator according to any one of the preceding claims adapted for use in the supply of an adhesive constituent based on a single component. 11 An applicator according to any one of claims 1 to 9 comprising two inlets (32, 34) to each of which a supply of adhesive component may be connected, the body comprising first and second passage means (33, 35) extending from the respective inlets, the head (40) comprising first and second passage means (50, 52) extending to the nozzle (60) and which are in communication with the first and second passage means (33, 35) in the head (40), respectively, as the head is rotated. 12 An applicator according to any one of claims 1 to 9 adapted for use in the dispensing of an adhesive composition comprising at least three components, the body comprising three inlets to each of which a supply of one of the components may be connected, the body comprising first, second and third passage means extending from the respective inlets, the head comprising first, second and third passage means extending to the nozzle and which are in communication with the first, second and third passage means in the head, respectively, as the head is rotated. 13 An applicator according to any one of the preceding claims wherein the or each nozzle (60) is of the kind known as a static mixing nozzle, having separate inlets for each component, to which the passage means in the head extend. 14 A machine for applying adhesive to a workpiece comprising: a) means (8) for supporting a workpiece in a plane; b) a gantry (13) upon which an adhesive applicator (28) is mounted for movement in a first direction A-A parallel to the plane of the supporting means (8), said applicator comprising at least one nozzle (60) from which adhesive may be dispensed against a workpiece (7) supported by the supporting means (8), the gantry (13) being mounted for movement relative to the supporting means (8) in a second direction B-B at right angles to said first direction and parallel to the plane of the supporting means; characterised in that the applicator (28) comprises a body (30) having an inlet (32, 34) to which a supply of adhesive or a supply of an adhesive component may be connected, and a head (40) mounted on the body (30) for rotary movement relative thereto, passages (33, 35; 50, 52) being provided which extend from the inlet (32, 34) through the body and through the head (40) to said nozzle (60) which passages during rotation of the head relative to the body are in communication for some at least of the time during each complete rotation of the head. 15 A machine according to claim 14 wherein the axis (C-C) about which the head rotates extends at right angles to said first and second directions (A-A; B-B). 16 A machine according to one of claims 14 and 15 wherein the supporting means (8) is afforded by a conveyor to move the workpiece (7) in said second direction whilst supporting the workpiece. 17 A machine according to one of claims 14 and 15 wherein the gantry (13) is moveable relative to the supporting means in said second direction (B-B). 18 A machine according to any one of claims 14 to 19 wherein operation of the applicator (28) and movement of the gantry (13) and of the supporting means (8) is carried out under computer control. 19 A machine according to any one of claims 14 to 18 wherein the applicator (28) is in accordance with any one of claims 1 to 13. 20 Any novel feature or novel combination of features hereinbefore described and/or shown in the accompanying drawings.

Inventors: BROADHEAD GARY JOHN, HAWKER JEREMY, SMALLBONE JOHN, BROADHEAD, GARY, JOHN, HAWKER, JEREMY, SMALLBONE, JOHN
Applicants: APOLLO CHEMICALS LIMITED, BROADHEAD GARY JOHN, HAWKER JEREMY, PRODEF ENGINEERS LTD, SMALLBONE JOHN, BROADHEAD, GARY, JOHN, HAWKER, JEREMY, PRODEF ENGINEERS LTD., SMALLBONE, JOHN
Application year: 2000
Main classification: B05B13
IPC codes: B05B13, B27G11