EP0777983A2 - Adhesive applicator - Google Patents

Abstract

A heatable basic body (28) has a duct (29) exposed to the hot-melt adhesive. At least one finger (14) with at least one adhesive-duct discharges the adhesive onto the surface being coated. The finger is set vibrating by a drive mechanism (34). the finger is divided into a number of small plates (36a,b,c) each possessing a duct for adhesive. The plates are separately spring mounted in a direction coinciding with the discharge direction of the adhesive. A rotor (60,61) rotates the finger on a rotational axis parallel with the discharge direction of the adhesive. The adhesive applicator head (13) has a pivot link (68).

Description

The invention relates generally to a device for applying adhesives and, more particularly, to a device for applying adhesives, in particular hot melt adhesives, to the shoe bottom or sole during shoe manufacture.

As an alternative to solvent-based adhesives, both aqueous dispersions and hot melt adhesives have been developed for shoe manufacture. Both alternatives require separate application procedures and devices.

Aqueous dispersions can be applied, for example, by spraying, as is known from DE 4 231 119 A1. The coating device provided for this purpose contains a spray head which has a channel which can be acted upon by adhesive and an additional channel which can be acted upon by spray air. Both channels are controlled by corresponding valve devices so that, if necessary, a jet which forms in front of the spray head can be switched on and off.

Such a spray head is only suitable for adhesives that can be cold atomized in the spray jet. This spray head is not intended for hot melt adhesives.

For the application of liquid adhesives, an adhesive application device is known from DE 3 440 417 C1, which has a nozzle head with an adhesive channel, which can be closed by a nozzle needle at its mouth. This is axially adjustable by means of a pneumatic actuation device and serves to meter the adhesive emerging from the mouth.

The adhesive application device is used to apply adhesives which are liquid at ambient temperature and which come into intimate contact with the corresponding leather surfaces after application. The application of hot melt adhesives is not intended with this device.

Hotmelt adhesives must be applied to the corresponding leather surfaces in a molten, i.e. heated, state, where they cool down relatively quickly. The adhesives go into a solid state of aggregation without running any further or penetrating into the leather. To create an intimate connection between adhesive and leather, however, it is necessary that the adhesive thoroughly wets the leather surface and, if necessary, penetrates into existing pores.

In addition, it is particularly important in shoe manufacture that the hotmelt adhesive is applied to the surface to be coated, that is to say, for example, the shoe bottom, with an essentially exact limitation, that is to say sharply contoured and in a uniform layer thickness. Lack of adhesive or -Excess in the edge area or blurred edges lead to unacceptable quality losses in the adhesive connection to be produced between the shoe bottom and the sole.

The object on which the invention is based is derived from this to provide a device for applying hot melt adhesives which enables adhesive to be applied in the required quality.

This object is achieved by the device with the features of claim 1.

The device has a heatable base body, which can be kept at an elevated temperature overall, at which the hot melt adhesive is at least viscous, but preferably has good flow properties. Depending on the adhesive used, the temperature is usually between 120 ° C and 180 ° C.

The hot-melt adhesive is passed via a channel present in the base body to a finger, which is used to dispense the adhesive onto a surface to be coated and to apply the adhesive thereon. For this purpose, the finger has at least one channel opening on its end face, which can be connected to the channel present in the base body or is permanently connected to it. The finger is in thermal contact with the base body, so that it has a temperature that roughly corresponds to this. Adhesive present in and on the finger therefore remains liquid.

Alternatively, the finger can be provided with a separate heater.

When the adhesive is applied to the shoe bottom or another surface to be coated, the Finger with his face in direct contact with the surface. To apply the adhesive, the finger is slid over the surface, creating a precisely contoured adhesive application. The face of the finger is preferably curved. An advantageous curvature is a curvature about a curvature axis lying transverse to the direction of movement of the finger. This enables an adhesive application with a uniform layer thickness.

The drive means, by means of which the finger can be made to vibrate, causes a constant relative movement between the finger and the surface to be coated. Glue escaping from the end of the finger is therefore rubbed in and, insofar as the porosity of the leather permits, incorporated into it. This causes an intimate contact to be made between the molten adhesive and the leather in a short time. The bond between the adhesive and the leather is created directly during the application process, regardless of the relatively rapid cooling after application. The vibration movement is preferably carried out in the direction of the aforementioned axis of curvature.

A further improvement in the application of adhesive can be achieved if the finger is divided into a number of lamellae, each of which has its own adhesive channel for dispensing adhesive. Each lamella is in itself a finger-like part which can be moved essentially orthogonally to the coating surface, independently of the other lamellae. As a result, the finger, which consists of several lamellae, easily adapts to unevenness or waves in the surface to be provided with adhesive, thereby avoiding gaps in the adhesive coating. This is supported by a resilient mounting of the finger or the lamellae, as a result of which it points towards the surface to be coated are resiliently biased. The lamella on the outside of the shoe bottom can take over the bearing guide and the other lamellae adapt to this resiliently on the shoe bottom.

In particular, an independent mounting and suspension of the slats leads to good adaptability to uneven surfaces.

The vibration movement of the finger is preferably an oscillation in a direction parallel to the surface to be coated. It causes the melted adhesive to be massaged in and helps to distribute it over the surface. Although in principle other directions of movement are also possible, it has been found that the vibration movement parallel to the surface is particularly effective with regard to the distribution and massaging in of the hot melt adhesive.

The finger containing a plurality of lamellae has an adhesive outlet opening on each lamella, the adhesive outlet openings preferably lying on a common line. When applying the adhesive, the entire device is moved in relation to the surface to be coated, the vibrating lamellae leaving an adhesive strip on the surface. The direction of movement is essentially perpendicular to the line that is described by the adhesive outlet openings. A rotating device enables the finger to be rotated about an axis of rotation which is substantially parallel to the direction of exit of the adhesive, so that contours limited in curvature can be traversed such that the adhesive outlet openings of the individual lamellae apply the adhesive next to one another without gaps in the direction of travel.

The guidance of the adhesive application head is particularly easy if the mathematical axis of rotation lies in the lateral boundary surface of a lamella. The axis of rotation then describes the edge of the surface to be coated when the adhesive application head moves.

The rotation of the finger is preferably brought about by means of a servo motor, the finger preferably being rotatable through an angle of 360 °. The rotation of the adhesive application head is made possible by a swivel joint in the adhesive feed to the head, to which a preferably heated plastic hose (preferably PTFE) is connected.

A needle valve upstream of the finger enables the adhesive feed to be switched on and off regardless of the rotational position of the finger. The needle valve can preferably be actuated pneumatically, it having no intermediate positions between "open" and "closed". In this case, the amount of adhesive to be applied is regulated via the pump pressure and the relative speed between the finger and the surface to be coated.

If necessary, however, an adjustable needle valve can also be provided.

The heating elements provided for heating the adhesive application head keep the adhesive flowable in the adhesive application head. The heating elements are preferably connected to a temperature control device which monitors the temperature and maintains it in a predetermined interval. This can also be achieved by a corresponding characteristic curve (PTC) of the heating elements.

It has proven to be advantageous to keep the adhesive in a closed container, in which has a nitrogen atmosphere with possibly a slight overpressure. This prevents the adhesive from absorbing water from the environment. The adhesive is preferably conveyed by means of a piston pump, which can also perform a metering function. Other pumps (such as gear pumps) can also be used, especially if a very long adhesive film has to be applied.

Fig. 1

eine Beschichtungseinrichtung zum Auftragen von Klebstoff bei der Schuhherstellung mittels eines Klebstoff-Auftragkopfes, der von einem Roboter geführt ist, in schematischer Darstellung,

Fig. 2

den Klebstoff-Auftragkopf nach Fig. 1, im Längsschnitt, geschnitten entlang der Linie V-V (Fig. 3), und in einem anderen Maßstab,

Fig. 3

den Klebstoff-Auftragkopf nach Fig. 1 in einer Draufsicht,

Fig. 4

den Klebstoff-Auftragkopf nach Fig. 1 in einem Längsschnitt (IV-IV in Fig. 3), der gegenüber dem in Fig. 2 dargestellten Längsschnitt um 90° gedreht ist und

Fig. 5

einen an dem Klebstoff-Auftragkopf vorgesehenen Finger zur Klebstoffabgabe, in geschnittener Darstellung, mit Schnittführung in einer Ebene V-V (Fig. 3).

In the drawing, an embodiment of the invention is shown. Show it:

Fig. 1

a schematic representation of a coating device for applying adhesive during shoe manufacture by means of an adhesive application head, which is guided by a robot,

Fig. 2

1, in longitudinal section, cut along the line VV (Fig. 3), and on a different scale,

Fig. 3

1 in a top view,

Fig. 4

1 in a longitudinal section (IV-IV in Fig. 3), which is rotated by 90 ° with respect to the longitudinal section shown in Fig. 2 and

Fig. 5

a finger provided on the adhesive application head for dispensing adhesive, in a sectional view, with a cut in a plane VV (FIG. 3).

1 illustrates a coating device 1 for applying hot melt adhesive to a shoe bottom 2 of a shoe unit 3. The coating device 1 has a five-axis robot 5, the arm 6 of which can be pivoted about a vertical axis 7. Further sections of the arm 6 are rotatably mounted in joints about horizontal axes 8, 9, 10 which are transverse to the vertical axis 7. At the end of the arm 6 there is a rotary drive, not shown, which rotatably carries an adhesive application head 13 about a pivot axis 11, which applies hot melt adhesive to the shoe bottom 2 with a finger 14. The horizontal axes 8, 9, 10 are provided with controlled drives so that the arm 6 assumes defined positions.

The adhesive application head 13 is supplied with hot melt adhesive from a supply unit 16 via a heated line 15. A piston pump 18, which can also be integrated in the feed unit 16, is used to convey the hot melt adhesive.

While the shoe unit 3 is held stationary by means of a clamping device 17, which is only symbolically indicated, the robot 5 allows a specific relative movement of the finger 14 to the shoe unit 3.

The adhesive application head 13 of the coating device 1 is shown in FIG. 2 cut separately along the section line VV, which can be seen from FIG. 3 showing the adhesive application head 13. The adhesive application head 13 is connected to the arm 6 of the robot 5 via a holder. The holder carries, by means of two machine screws 21, 22, a carrier body which has a section designed in the manner of a bushing with a through bore 25. Two in the through hole 25 at a distance from each other Bearing bushes 26, 27 arranged approximately at the ends support a base body 28 which protrudes from the through bore 25 with both ends and which is provided with a central through channel 29. The essentially cylindrical base body 28, which at its lower end in FIG. 2 has a collar which is supported on the carrier body 24 by means of an intermediate disk 31, carries the finger 14 via a corresponding bearing 33, which can be set in vibration by a drive device 34. The bearing 33, which is shown in detail in Fig. 5 and explained later, is rotatably connected to the base body 28 and carries the finger 14 consisting of three individual lamellae 36a, 36b, 36c, which laterally, that is transversely to the Axis of rotation of the base body 28 is displaceable. The slats 36a, 36b, 36c are arranged so that they abut one another and an outer slat lies with its side surface on an axis of rotation 37 about which the base body 28 can be rotated. The finger 14 can also have more slats.

As can be seen in FIG. 5, the lamellae 36a, 36b, 36c each have an adhesive channel 38a, 38b, 38c opening on their end face. The end face of each lamella 36a, 36b, 36c is curved to match its respective neighboring lamella 36a, 36b, 36c. The lamellae 36a, 36b, 36c, which lie against one another with their flat side surfaces, thus define a surface which is straight in the transverse direction and curved in the direction of travel for the application of fleece.

The slats 36a, 36b, 36c are axially displaceably mounted in a base 39 which has a collecting channel 41. This leads from the rear sides of the fins 36a, 36b, 36c to a through hole 42 which is provided in the bearing 33 and communicates with the through channel 29.

The base 39 is rigidly connected to a cross pin 43 which is supported at both ends in corresponding bores in the bearing 33. The base 39 is prestressed to a lateral extreme position, that is to say to the drive device 34, by means of a helical spring seated on the transverse pin 43. The drive device 34 is an electric motor held on the bearing 33 with a cam or eccentric 46 on the output shaft, which is in contact with the end face of the cross pin 43. A rotation of the eccentric 46 causes an axial movement of the cross pin 43 and thus a displacement of the slats 36a, 36b, 36c in the lateral direction by fractions of a millimeter or at most a few millimeters.

As can be seen in particular from FIG. 4, each lamella 36 has a tubular shaft which is seated in a bore in the base and which serves for the axially displaceable mounting of the respective lamella 36 (in the direction of the axis of rotation 37). On both sides of the respective bore provided in the base, blind bores 47, 48 serving as seat openings are provided, in each of which a helical spring is seated, which prestresses the lamella towards the outside. A sheet metal flap or latch 51 provided on the base engages behind the lamellae 36 on an open groove 52 and thus holds the lamellae with the respective shafts in the base 39 in such a position that their curved end faces lie in a common curved plane.

As is also apparent from FIG. 4, the base body 28 has two bores 53, 54 which are parallel to the through-channel 29 and in which electrical heating elements 56, 57 are seated. These are in thermal contact with the base body 28 and keep both this and the finger 28 at a desired elevated temperature.

A further eccentric axial bore can be seen from FIG. 2, which is used to pass an electrical power supply to the electric motor of the drive device 34.

The base body 28 is connected at its end remote from the finger 14 in a rotationally fixed manner to a gearwheel 60, which sits concentrically on the base body 28 and is in drive connection with its spur toothing with a rotary drive 61 shown in FIG. 4. The rotary drive 61 is an electric geared motor, which is rigidly connected to the carrier body 24 via a separate holder. The rotary drive 61 thus serves the specific rotation of the base body 28 and thus the finger 31. A control device for controlling the geared motor guides it so that the flank (outer side surface) of the lamella 36a is tangential to the edge of the shoe bottom 2 to be coated.

To act upon the through-channel 29 with hot-melt adhesive, the base body 28 carries a guide and locking piece 62 on the gearwheel 60, which is sealed onto the base body 28 by means of a seal 63 and is connected to the base body 28 in a rotationally fixed manner. The guide and closure piece 62 has a guide bore 66 aligned with the through-channel 29, which is in fluid communication with a radially extending side channel 67. This is connected via a rotary coupling 68 to the heated line 15, which is used to supply hot melt adhesive. The rotary coupling 68 is eccentric to the axis of rotation of the base body 28 and, in the case of a flexible line 15, enables the base body 28 and the parts connected to it to be rotated without the line 15 being rotated.

The guide and locking piece 62 carries a pneumatic drive 71, which is made in one piece by means of a this trained spacer 72 and machine screws 73 is rigidly held. The pneumatic drive 71 is used for the longitudinal adjustment of a nozzle needle 75, which extends out of the pneumatic drive 71 through the guide bore 66 into the through channel 29 and which is seated with a valve cone 76 on the edge of the through bore 42 of the bearing 33. The through bore 42 forms a valve seat for the valve cone 76, the valve thus formed regulating the access of adhesive to the finger 14.

The nozzle needle 75 is stepped and sits sealed by means of an O-ring in the guide bore 66. Below the O-ring and above the side channel 67, the nozzle needle 75 tapers to a constant smaller diameter, so that an annular channel between the through channel 29 and the nozzle needle 75 is formed with a cross section that allows the flow of hot melt adhesive.

At its end remote from the valve cone 76, the nozzle needle 75 carries a piston 77 which divides two working chambers 78, 79 into a cylinder chamber provided on the pneumatic drive. The nozzle needle 75 thus simultaneously forms a piston rod which is sealed out of the cylinder chamber. Both working chambers 78, 79 are each connected to a compressed air connection 81, 82, so that the working chambers 78, 79 can be optionally pressurized with compressed air.

The coating device 1 works as follows:

To coat the shoe bottom 2 of the shoe unit 3, the relevant shoe unit 3 is first clamped by means of the tensioning device 17. This is the adhesive application head held by the arm 6 of the robot 5 13 in a position distant from the shoe unit 3 and the tensioning devices 17 in the rest position.

To carry out the coating process, the heated adhesive application head 13 is brought to the shoe unit 3 by specifically pivoting the arm 6 in such a way that the finger 14 sits on the shoe bottom 2. The rotational position of the finger 14 is adjusted by targeted actuation of the rotary drive 61 so that a line defined by the mouths of the adhesive channels 38a, 38b, 38c is approximately perpendicular to the edge of the shoe bottom 2.

The drive device 34 now causes the base 39 and thus the slats 36a, 36b, 36c to vibrate perpendicular to the edge of the shoe bottom 2 with an amplitude of at most a few millimeters or less and a frequency of approximately 200 Hz.

In order to enable the hot melt adhesive to be applied to the shoe bottom 2, the working chamber 79 is now pressurized with compressed air, as a result of which the valve needle 75 is withdrawn axially and the valve cone 76 clears the through bore 42. Liquid hot-melt adhesive standing in the through-channel 29 is now discharged through the through-bore 42, the collecting channel 41 and the adhesive channels 38a, 38b, 38c on the front side of the finger 14 due to the pressure of the hot-melt adhesive supplied by the feed unit 16 and the piston pump 18. The adhesive application head 13 has moved so far to the shoe bottom 2 that the individual lamellae 36a, 36b, 36c of the finger 14 are spring-loaded independently of one another against the force of their respective coil springs while adapting to the height profile of the shoe bottom 2, the respective location of the shoe bottom 2 the mouth of the adhesive channel 38a, 38b, 38c largely closed. This prevents excessive adhesive leakage.

The molten hot melt adhesive is massaged into the surface to be coated by the lateral vibration movement of the lamellae 36a, 36b, 36c. The adhesive remains liquid during this process due to the heat conduction between the base body 28 containing the heating elements 56, 57 and the fins 36a, 36b, 36c.

In order to coat the desired area of the shoe bottom 2, the adhesive application head 13 is now guided by deliberately moving the arm 6 along the outer contour of the shoe bottom 2. By actuating the horizontal axis 10, the pivot axis 11 and in particular by actuating the rotary drive 61, the adhesive application head 13 is guided such that the finger 14, while vibrating along the shoe bottom 2, travels with the axis of rotation 37 of the edge of the shoe bottom, the axis of rotation 37 is perpendicular to the shoe bottom and the line defined by the mouths of the adhesive channels 38a, 38b, 38c is held perpendicular to the edge of the shoe bottom. Such a guiding of the finger 14 enables a cleanly contoured application of adhesive, the vibration of the finger 14 allowing a massage and thus an intimate contact between the adhesive and the shoe bottom 2. By the abutment of the shoe bottom 2 at the mouths of the adhesive channels 38a, 38b, 38c, excessively large quantities of adhesive are prevented from escaping and a uniformly thick layer is applied.

As soon as the finger 14 moving at moderate speed comes out of contact with a coated area of the shoe bottom, this begins to cool rapidly, so that the adhesive is inactive after a few seconds. If the shoe bottom 2 is coated as desired, the hot melt adhesive supply to the finger 14 is switched off, by pressurizing the working chamber 78 of the pneumatic drive 71 and depressurizing the working chamber 79. The valve cone 76 closes the through hole 42 so that no further hot melt adhesive emerges. The shoe unit 3 can now be removed, the adhesive application head 13 remaining in stand-by mode until the coating of the next shoe unit. In this, it is kept at a temperature by the heating elements 56, 57 at which the hot-melt adhesive is liquid.

The division of the finger 14 into three individual lamellae, each of which is sprung separately, in conjunction with the lateral vibration movement of the lamellae 36a, 36b, 36c enables a uniform and good application of adhesive to the shoe bottom 2 with easy adaptation to existing curvatures and unevenness.

The guidance of the adhesive application head 13 can be further improved if the holder 19 is designed as a pneumatically actuated linear guide, so that the entire adhesive application head 13 can be moved up and down parallel to the axis of rotation 37.

To apply hot melt adhesives to shoe bottoms or soles during shoe manufacture, an adhesive application head is provided which has a heatable base body with a channel which can be acted upon with adhesive and on which a finger vibrating during operation is held. The finger is used to apply the adhesive and, for this purpose, has a channel opening on the end face, through which the hot-melt adhesive is guided onto the shoe bottom. In operation, the finger massages the hot melt adhesive into the leather surface to be coated. The cooled hotmelt adhesive is inactive and can be reactivated to attach a sole by heating.

Claims (16)

Device (1) for applying adhesives, in particular hot melt adhesives, with an adhesive application head (13), with a heatable base body (28) which has a channel (29, 42, 41, 38) to which hot-melt adhesive can be applied, with at least one finger (14) with at least one adhesive channel (38) for dispensing the adhesive onto a surface (2) to be coated, and with a drive means (34) by means of which the finger (14) can be made to vibrate. Device according to claim 1, characterized in that the finger (14) is subdivided into a number of lamellae (36a, 36b, 36c) which each have an adhesive channel (38a, 38b, 38c) for dispensing adhesive. Device according to claim 1 or 2, characterized in that the finger (14) or the lamellae (36a, 36b, 36c) are spring-mounted. Apparatus according to claim 3, characterized in that the lamellae (36a, 36b, 36c) are resiliently mounted independently of one another in a direction which essentially corresponds to the direction of exit of the adhesive. Device according to claim 1, characterized in that the vibration movement is an oscillation in a direction which is substantially parallel to the surface (2) to be coated. Device according to Claim 1, characterized in that it has a rotating device (60, 61) by means of which the finger (14) can be rotated about an axis of rotation (37) which is substantially parallel to the direction of exit of the adhesive. Apparatus according to claims 2 and 6, characterized in that one of the lamellae (36a) has a lateral boundary surface which contains the axis of rotation (37). Apparatus according to claim 7, characterized in that the rotating device (60, 61) contains a servo motor which enables a specific rotation of the finger (14) in such a way that the lateral boundary surface when the finger (14) moves along the edge of the surface to be coated Surface (2) can be aligned tangentially to the edge in all positions. Apparatus according to claim 1, characterized in that a swivel joint (68) is provided for supplying the adhesive to the adhesive application head (13). Device according to claim 1, characterized in that the adhesive application head (13) contains a remote-controlled needle valve (76, 42) with which the flow of adhesive to the finger (14) can be switched on and off. Device according to claim 1, characterized in that the adhesive application head (13) contains a remote-controlled needle valve (76, 42) with which the flow of adhesive to the finger can be regulated. Apparatus according to claim 10, characterized in that the needle valve (76, 42) can be actuated by a pneumatic drive device (71). Device according to Claim 1, characterized in that heating elements (56, 57) are provided, by means of which the adhesive application head (13) can be heated to an elevated temperature at which the adhesive is flowable. Device according to claim 1, characterized in that the adhesive application head (13) is connected to a heatable line (15) for supplying adhesive. Apparatus according to claim 1, characterized in that a closed container (16) is provided to provide an adhesive supply, in which a nitrogen atmosphere or an atmosphere of anhydrous compressed air can be built up. Apparatus according to claim 15, characterized in that a piston pump (18) is provided for conveying the adhesive, by means of which melted adhesive can be conveyed from the container to the adhesive application head (13).

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