HK1179208A - Electric application head for dispensing a free-flowing medium, and device comprising such an electric application head - Google Patents

Description

Electrocoat spray head for applying a free-flowing medium and coating device comprising an electrocoat spray head

Technical Field

The invention relates to a coating head for coating a free-flowing medium, and to a coating device comprising at least one such coating head. In particular, it relates to the application of adhesives and the use of hot melt adhesives. The invention may also be used for the controlled application of cold glue or adhesives containing aggressive (e.g. corrosive) components.

This application claims priority from european patent office EP10151806.6 patent application, filed on a date of 2010, month 1, and day 27.

Background

In many industrial manufacturing processes, adhesives, sealants, and similar free-flowing media are used that are applied or sprayed in fluid form onto a workpiece or substrate.

The corresponding application head must be robust and allow for precise, high precision application of the medium. The application head can also be quickly switched to dispense the amount of adhesive applied or apply them precisely in dots or stripes. Furthermore, the application head cannot be too large, since the space available in the corresponding application device is often limited.

If hot melt adhesives are to be treated, another problem is faced. Thus, for example, high heat inside the coating head can damage the drive unit. Still other types of adhesives contain aggressive additives. For example, the pH of the adhesive may thus be in the acidic range. The adhesive may also contain corrosive or abrasive active ingredients. Appropriate measures must be taken in order to protect the coating head.

The problem presented here is to provide an application head which is accurate and reliable in operation, avoiding or completely obviating some of the drawbacks of the previously known solutions.

Disclosure of Invention

The problem is solved according to the invention by a coating nozzle according to claim 1 and a coating installation with a corresponding control module according to claim 6.

The first coating nozzle according to the invention is designed in particular for coating free-flowing media. It comprises a (nozzle) chamber inside the application head and a nozzle needle, needle valve or slide valve (collectively referred to herein as "movable element") which is mounted in a movable manner inside the nozzle chamber. The movable element releases the outlet opening for a short time with each actuation. The application head can also be actuated in the opposite way, in which case the movable element closes the outlet opening for a short time with each actuation. A supply channel is provided which is connected to the (nozzle) chamber and can be in fluid connection with the supply line. A free-flowing medium can be introduced into the (nozzle) chamber via said supply line and supply channel. The driver is used for generating the opening action or the closing action of the movable element. A lever arm is provided, a first end of which is connected in a movable manner to the rear end of the movable element, and a second end of which is connected/coupled to a drive. Furthermore, the application head comprises a membrane suspension with the membrane. The lever arm extends across the surface of the diaphragm in a substantially vertical manner. The purpose of the diaphragm is to allow the lever arm to be connected to the application head in a movable manner. Furthermore, the diaphragm suspension acts as a seal to prevent the free-flowing medium from escaping from the (nozzle) chamber. Furthermore, the membrane is preferably made of a material that is resistant to free-flowing media. In all embodiments, the membrane preferably has a resistance to heat and/or corrosion, and/or wear, and/or to chemical additives in the medium M.

According to an embodiment, the membrane may comprise at least one sealing ring, which serves as a seal and serves to elastically clamp the membrane in the application head. This embodiment can be used in all embodiments of the invention, for example, to provide a better seal for escaping adhesive.

In a particularly preferred embodiment, a metal diaphragm is provided which can perform a reciprocating movement particularly quickly to allow rapid opening or closing of the outlet opening. Such a metal diaphragm is particularly suitable for alternating loads at high frequencies, i.e. for embodiments that need to be opened or closed very quickly. Metal diaphragms are particularly advantageous and can be used in all embodiments of the invention.

The invention is very particularly suitable for thermoplastic (hot melt) adhesives. However, it is also suitable for aggressive glues of various types and, for example, cold glues.

Further advantageous embodiments of the invention are set forth in the dependent claims.

Drawings

The details and advantages of the invention are described in more detail on the basis of the following exemplary embodiments, partly in conjunction with the accompanying drawings. All the figures are schematic and not drawn to scale, and corresponding structural elements are denoted by the same reference numerals in the different figures, even if they are designed in different forms in detail. Wherein:

FIG. 1 is a perspective view of a first embodiment of the present invention;

FIG. 2 is a schematic cross-sectional view of another embodiment of the present invention;

FIG. 3A is a top view of a diaphragm according to another embodiment of the present invention;

FIG. 3B is a cross-sectional view of a diaphragm suspension according to another embodiment of the present invention;

FIG. 4 is an enlarged cross-sectional schematic view of another embodiment of the present invention;

FIG. 5 is a schematic side view of another embodiment of the present invention;

FIG. 6A is a partial schematic view of another embodiment of the present invention illustrating a preferred thermal decoupling connection between the actuator and the applicator tip;

fig. 6B is a partially enlarged view of fig. 6A.

Detailed Description

The principle of the present invention will be described below on the basis of the first embodiment. Fig. 1 shows an application apparatus 100, said application apparatus 100 having a plurality of application heads 15 arranged in a row, nozzle outlet openings 12, and adhesive supply lines 16 which can be switched independently. Instead of the nozzle outlet 12 shown in the figures, other outlet openings 12 may be used. The shape, configuration and design of the outlet orifice 12 may depend on whether there is a nozzle needle, needle valve or slide valve inside the application head 15 acting as the movable element 11.

Each outlet orifice 12 is provided in a respective application head 15. Each application head 15 is designed for the application of a free-flowing medium M, in particular for the application of adhesives, said application head 15 comprising internally a (nozzle) chamber 10. In the example shown, a nozzle needle 11 is fitted inside the (nozzle) chamber 10, said nozzle needle 11 being movable up and down inside the (nozzle) chamber 10, the outlet orifice 12 being released by an opening action P of the nozzle needle 11. Fig. 2 shows an arrow P pointing upwards. The opening movement in the direction of the arrow P lifts the nozzle needle 11, which releases the outlet opening 12, so that the medium M can be discharged from the nozzle chamber 10 to the outlet opening 12. In fig. 1, four coating heads 15 simultaneously and continuously dispense a medium M to form a web (bead) in a band shape. Said band is produced by the transfer action of the web K or of the workpiece or substrate. The corresponding direction of motion is determined by V.

Inside the coating head there is a supply channel 13 connected to the (nozzle) chamber 10. The supply channel 13 can be in fluid connection with a supply line 16, so that a free-flowing medium M can be introduced into the (nozzle) chamber 10. Four separate supply lines 16 are shown in figure 1. However, a plurality of coating heads 15 may also be provided with a common supply line 16.

Furthermore, an actuator 20 for initiating the opening movement P of the nozzle needle 11 is provided. In fig. 1, the actuator 20 is attached or flanged to the coating nozzle 15. Preferably, the actuator 20 includes a separate actuator 20 for each application head 15 so that each outlet orifice 12 can be opened or closed individually (i.e., independently of the others).

For example, in some embodiments, such as that shown in FIG. 2, the actuator 20 is preferably disposed in a spaced apart position from the applicator head 15. However, in the arrangement between the actuator 20 and the application head 15, it is important that the mutual distance is precisely determined and is stable, which applies to the arrangement of fig. 1 and 2. This aspect is important because any spatial variation will have an effect on the function or manner of operation of the lever arm 30. Details regarding the lever arm 30 will be described below.

This will be explained in further detail on the basis of a further embodiment, which is shown in cross-section in fig. 2. Fig. 2 shows a cross-sectional view through an individual application head 15, wherein the actuators 20 are arranged in spaced-apart positions (i.e. spatially separated). According to the invention, the applicator head 15 comprises, in correspondence with each actuator 20, a lever arm 30, a first end 31 of the lever arm 30 being connected in a movable manner to the rear end of the nozzle needle 11 or of another movable element, and a second end 32 of the lever arm 30 being connected to the actuator 20. A diaphragm 34 with a diaphragm suspension 33 is used, the lever arm 30 passing through the diaphragm 34 with the diaphragm suspension 33. The purpose of the diaphragm suspension 33 is to allow the lever arm 30 to be connected to the application head 15 in a movable manner. Furthermore, the membrane suspension 33 acts as a seal to prevent the free-flowing medium M from escaping from the (nozzle) chamber 10. That is, the diaphragm 34 or the diaphragm suspension 33, respectively, has a dual function. Furthermore, depending on the design of the membrane 34, it has a protective function against the temperature, corrosion, wear and chemical additives of the medium M.

The following details show the distinctive features of this embodiment. The (nozzle) chamber 10 is realized in such a way that: in the lower region of the (nozzle) chamber 10, close to the outlet opening 12, a stop point 17 or stop surface (also referred to as needle seat) is provided, respectively, for the tip 18 of the nozzle needle 11. In fig. 2, the nozzle needle 11 is shown in the closed position, i.e. the tip 18 of the nozzle needle 11 is sealingly seated on the blocking point 17, no medium M can escape through the outlet opening 12. Once the nozzle needle 11 is lifted by the mouth opening action P, the outlet orifice 12 is released and the medium M can be discharged.

The nozzle needle 11 is connected in a movable manner (like a toggle connection) to the region of the trailing end 14 of the lever arm 30. The nozzle needle 11 is more or less "dangling" in the nozzle chamber 10. Since the lower part of the nozzle chamber 10 and the nozzle needle 11 (the region close to the interruption point 17) is made rotationally symmetrical, in practice, conical, the nozzle needle 11 is centrally guided during the downward movement. Furthermore, the medium M flowing from the supply channel 13 through the (nozzle) chamber 10 in the direction of the outlet opening 12 contributes to a stable and self-centering of the respective nozzle needle 11. Such "dangling" mounting or suspension structures may be used in all embodiments.

The lever arm 30 is implemented here in such a way that it comprises a flat, rectangular or strip-shaped rod on which preferably several holes 39 are provided. These holes 39 serve to make the weight of the rod lighter in order to reduce the amount of acceleration. In addition, these holes 39 allow the connection point a of the actuator 20 to be shifted. Thus, if the effective lever arm is to be lengthened, the actuator 20 (or the respective attachment point A) can be moved further towards the second end 32, and vice versa. In the example shown, the actuator 20 is located almost at the end 32, i.e. the effective lever arm is relatively long. The closer the actuator 20 (or the respective connection point a) is moved towards the diaphragm suspension 33, the shorter the effective lever arm. With a long lever arm, a reduction takes place, i.e. a large movement P1 is reversed to give rise to a small movement P. In fig. 2, the deceleration factor is about 5:1 (i.e., the absolute value of the action P1 is about 5 times the absolute value of the action P). In the case of a small lever arm, a step-up transmission takes place, i.e. a small movement P1 is reversed to give rise to a large movement P.

However, the lever arm 30 may be a rod or shaft of any other shape. The lever arm 30 is preferably made of a torsion resistant material. In addition, the lever arm 30 is as light as possible to allow a smaller amount of movement or acceleration. In all embodiments, the diaphragm 34 serves as an kinematic support for carrying/suspending a portion of the lever arm 30. Furthermore, in all embodiments, the diaphragm 34 constitutes a precise fulcrum or tilt point (referred to as a virtual pivot axis) of the lever arm 30.

In order to enable the lever arm 30 to be suspended or held in the diaphragm suspension 33, a cylindrical rod 40 is provided on the lever arm 30 in the embodiment shown. The cylindrical rod 40 presses or clamps the diaphragm 34, thereby suspending the lever arm 30 from the diaphragm 34. The detailed structure of a typical preferred arrangement can be deduced from fig. 4. This suspension structure is applicable to all embodiments.

Furthermore, as shown in fig. 2 and 4, the membrane 34 may include one or two sealing rings 35, said sealing rings 35 allowing the membrane 34 to be resiliently clamped in the application head 15. The described sealing ring 35 is optional. For clamping purposes, the application head 15 may comprise a removable piece or cover (details not shown in the figures). If the removable piece or cap is removed, a diaphragm 34 including an optional seal 35 may be inserted. The diaphragm 34 is then held in place by re-tightening the removable member or cover.

As shown in fig. 4, an optional pressure connection 38 is provided on the rear side of the membrane 34, i.e. on the side facing away from the (nozzle) chamber 10, said pressure connection 38 serving for mechanical locking of the membrane 34. With this preferred embodiment, the diaphragm 34 is prevented from over-stretching in the event of excessive pressure in the nozzle chamber 10. In all embodiments, the diaphragm 34 is preferably designed and arranged such that it is only bent and tensioned, thereby extending its useful life.

In various embodiments, it is preferred to use a metal diaphragm 34 that is particularly well suited for alternating loads at high frequencies. Whether the membrane 34 is a unitary membrane surface made of metal or a planar membrane substrate (e.g., made of plastic) with a metal layer/metal vapor deposition is referred to as a metal membrane 34.

As shown in fig. 2 and 4, the reverse operation P1 by the actuator 20 causes the nozzle needle 11 to generate a reverse opening operation P. The lever arm thus ensures a defined deceleration or acceleration transmission and reversal of motion.

Fig. 3A shows details of a preferred embodiment of the diaphragm 34. The diaphragm 34 includes a groove 36 to increase its elasticity. Furthermore, a central passage 37 is provided through which the lever arm 30 extends in the mounted state. The position of the sealing ring 35 is shown in fig. 3A. This design of the diaphragm 34 is particularly suitable for a metal diaphragm 34, the purpose of which is to provide the required elasticity of the metal diaphragm 34.

By providing the slot 36 specifically, two small channels 42 are formed at the 3 o 'clock and 9 o' clock positions, the slot 36 being almost a complete circle. These two small channels 42 allow the inner portion 41 of the diaphragm 34 to flex, i.e. the inner portion 41 of the diaphragm 34 is a circular area defined by the radial boundaries of the slots 36. The two small channels 42, in combination with the inner portion 41 of the membrane 34, similarly define a virtual pivot axis VA. This virtual pivot axis VA is indicated by a dash-dot line in fig. 3.

Fig. 3B shows details of a preferred embodiment of the diaphragm suspension 33. Here, the fastening of the lever arm 30 to the membrane 34 can be seen. The fixing structure is realized by a rod 40. In the illustrated embodiment, the interior of the rod 40 is hollow to reduce weight. In order that the medium M does not escape through the inside of the lever 40, for example, caps 43 or sealing members may be provided at both ends of the lever 40. The position of the virtual pivot axis VA is also shown in fig. 3B. The details shown in fig. 3B may be applied to all embodiments.

Fig. 5 shows details of another embodiment of the present invention. The configuration of the elements is chosen here in a different way, but the function is the same. The linear action of the actuator 20 is converted into an opening action of the nozzle needle 11 located inside the application head 15. The actuator 20 is also implemented separately (i.e., spatially separated) from the coating head 15, as in fig. 2.

In the various embodiments, an electromagnetic/pneumatic/piezoelectric actuator is suitable as actuator 20, said actuator 20 producing a corresponding linear movement P1 (up and down movement) at the desired frequency, relayed, decelerated or accelerated by the highly efficient movable lever arm 30 to the nozzle needle 11, where it induces the linear movement P. However, it is preferred for piezoelectric actuator 20 to operate with a step-up drive to convert the very small motion of the piezoelectric actuator into a sufficiently large opening or closing motion P.

The electromagnetic drive 20 is constructed according to the principle of a voice coil motor or Lorentzcoil (Lorentzcoil), which electromagnetic drive 20 has proven itself. In this case, 1: a lever ratio or step-down transmission of 1 is particularly suitable as the effective transmission ratio in this example. Voice coil motors or lorentz coils may be used for all embodiments.

The stroke of the nozzle tip 18 or exit orifice 12 is preferably approximately between 0.1 mm and 1 mm. For 1: 1 lever ratio, the actuator 20 must therefore produce a corresponding counter-phase action P1 with a stroke of 0.1 mm to 1 mm. With suitable control of the driver 20, for example by means of the drive module 21, the action characteristics of the nozzle needle 11 or of another movable element can be set or even adjusted; the driver module 21 may be arranged near the driver 20, as in the example shown in fig. 5. If desired, a suitable motion profile can be stored in order to slow down the nozzle needle 11 shortly before it hits the blocking point 17. This measure makes it possible to prolong the service life of the nozzle needle 11 and of the application head 15. A corresponding drive module 21 can be used for all embodiments.

The greater the selectable lever reduction gear ratio, the greater the accuracy with which the nozzle needle 11 is moved, since the large movement P1 of the actuator 20 is reduced to a small movement P of the nozzle needle 11. However, a disadvantage of such a large reduction transmission ratio is that the stroke covered by the drive side is lengthened, which makes it possible to reduce the frequency or maximum period respectively achievable by the opening and closing action of the nozzle needle 11.

In a preferred embodiment, the intelligent controller (e.g., in the form of a driver module 21) on the driver side of the driver 20 is designed such that the current injected into the driver 20 can be observed. When the current increases, this current increase indicates that the nozzle needle 11 or the movable element touches the blocking point 17. By means of the intelligent controller, a gradual adapted motion profile stored in the driver module 21 can be executed, which motion profile can be defined in all embodiments by means of a referenced parameterization; when the current signal indicates a later than before occurrence of the current increase phenomenon, the motion profile causes a concomitant increase in motion P1 on the drive side, thereby compensating for wear of needle tip 18. This is because the current increase phenomenon occurs later, meaning that the needle tip 18 touches the interruption point 17 later than before. This represents a phenomenon of wear. The use of such an intelligent controller (for example in the form of a drive module 21) makes it possible to extend the service life of the application head 15, since the nozzle needle 11 or the movable element can be replaced at a later time.

In a preferred embodiment, the intelligent control (for example in the form of a drive module 21) on the drive side of the drive 20 is designed such that the movement of the nozzle needle 11 or of the movable element can be adjusted according to a predefined movement trajectory. The controller can monitor the switching time and the stroke of the nozzle needle 11, and can automatically correct the coating pattern of the coating head 15.

A driver module 21 may be provided directly on each driver 20 so that the drivers 20 may be operated with a 24VDC signal, which is directly from the PLC (PLC stands for programmable logic controller). This has the advantage that each application head 15 can be operated individually. A corresponding drive module 21 can be used for all embodiments.

In a preferred embodiment, an intelligent controller on the drive side of the drive 20 is designed such that it can output error, warning, service or maintenance indicator signals. This method can be used in all embodiments.

An advantage of the invention is that a spatial thermal separation between the actuator 20 and the medium M flow-through part of the application head 15 is possible (see, for example, fig. 5). This can reduce those problems caused on the drive side by high temperatures, particularly in the case of a low-temperature or high-temperature heat medium M.

The thermal separation between the drive 20 and the application head 15 is preferably in the form of a screwless connection, as can be seen in fig. 6A and the enlarged detail 6B. An insulating plate 44 is mounted on the coating head 15. Two locating pegs are provided on the applicator head side of the insulation panel 44 and four spacer/locating bolts 46 are provided on the drive side thereof. The coating head 15 and the actuator 20 are fixed by two cables 47, preferably steel cables. Preferably a non-heat conducting cable 47 is used. The cable 47 is secured to the applicator head 15 at point X1 and is pulled tight by the tensioning device 48 in the actuator 20. With this arrangement, the application head 15 and the drive 20 are ideally secured without metallic connections (in this arrangement only by two thin cables 47).

In all preferred embodiments, the lever arm 30 causes a reversal of the direction of motion (point P1 being anti-phase to P; see FIG. 2); and enlargement or reduction of motion, depending on the length setting of the lever arm, i.e., P > P1, referred to as step up drive, P1> P, referred to as step down drive. Furthermore, the angular disposition of the lever arm 30 with respect to the mobile element 11 allows to dispose said membrane 34 in an area that is not directly affected by the flowing medium M.

List of labels

10 (nozzle) cavity

11 moving element (for example, nozzle needle)

12 outlet hole

13 feed channel

14 rear end of nozzle needle 11

15 coating nozzle

16 supply line

17 point of interruption

18 tip

20 driver

21 drive module

30 lever arm

31 first end

32 second end

33 diaphragm suspension

34 diaphragm

35 sealing ring

36 groove

37 center channel

38 pressure connecting part

39 holes

40 cylindrical rod

41 inner part of the membrane 34

42 small channel

43 Cap

44 heat insulation plate

45 positioning bolt

46 spacer/spacer

47 cable

48 tension adjuster

100 coating apparatus

A connection point

K paper web (paperweb)

M free flowing medium

Direction of motion of V

VA virtual pivot axis

P opening action

P1 anti-phase action

Point X1

Claims (13)

1. A coating nozzle (15) for coating a free-flowing medium (M) has

-a chamber (10) inside the coating nozzle (15),

-a mobile element (11) mounted in a mobile manner inside the chamber (10) which releases or closes the outlet orifice (12) by the action (P) of said nozzle needle (11),

-a supply channel (13) connected to the chamber (10) and connectable in fluid connection with a supply line (16) for introducing a free-flowing medium (M) into the chamber (10),

-an actuator (20) for generating an opening movement (P) of the mobile element (11), characterized in that said application head (15) comprises:

-a lever arm (30) having a first end (31) movably connected to the trailing end (14) of the mobile element and a second end (32) connected to a driver (20),

a diaphragm suspension (33) with a diaphragm (34),

-said lever arm (30) passes through a diaphragm (34) of said diaphragm suspension (33),

-said membrane suspension (33) being intended for movably connecting the lever arm (30) to the application head (15), and

-said diaphragm suspension (33) acting as a seal to prevent the free-flowing medium (M) from escaping from the chamber (10).

2. Coating sprayhead (15) according to claim 1, characterized in that the membrane suspension (33) comprises, in addition to the membrane (34), at least one sealing ring (35) which serves as a seal and serves to resiliently clamp the membrane (34) in the coating sprayhead (15).

3. Coating sprayhead (15) according to claim 1 or 2, characterized in that the membrane (34) is a metal membrane (34).

4. Coating sprayhead (15) according to claim 1, 2 or 3, characterized in that the membrane (34)

-with grooves (36) to increase its elasticity, an

-with a central passage (37) through which the lever arm (30) extends in the mounted state.

5. Application head (15) according to claim 1, 2, 3 or 4, characterized in that the configuration of the lever arm (30), of the mobile element (11) and of the membrane suspension (33) with the membrane (34) is chosen such that the opening or closing movement (P) of the mobile element (11) is in anti-phase with the movement (P1) of the second end (32) of the lever arm (30).

6. A coating device (100) for coating a free-flowing medium (M) has

A supply line (16) for a free-flowing medium (M),

-a coating nozzle (15) with an inner chamber (10),

-a mobile element (11) mounted in a mobile manner inside the chamber (10) which releases or closes the exit hole (12) by the action (P) of said mobile element (11),

-a supply channel (13) fluidly connected to the chamber (10) and to a supply line (16) for introducing a free-flowing medium (M) into the chamber (10),

-an actuator (20) for generating an opening movement (P) of the movable element (11), and

-a control module (50),

characterized in that said coating device (100) comprises:

-a lever arm (30) having a first end (31) movably connected to the trailing end (14) of the mobile element and a second end connected to a driver (20),

-a membrane suspension (33) with a membrane (34) placed on or in said application head (15),

-said lever arm (30) passes through a diaphragm (34) of said diaphragm suspension (33),

-said membrane suspension (33) being intended for movably connecting the lever arm (30) to the application head (15), and

-said diaphragm suspension (33) acting as a seal to prevent the free-flowing medium (M) from escaping from the chamber (10).

7. The coating device (100) according to claim 6, characterized in that the membrane suspension (33) comprises, in addition to the membrane (34), at least one sealing ring (35) which serves as a seal and serves to elastically clamp the membrane (34) in the coating head (15).

8. The coating device (100) according to claim 6 or 7, characterized in that said membrane (34) is a metal membrane (34).

9. The coating device (100) according to claim 6, 7 or 8, characterized in that said membrane (34)

-with grooves (36) to increase its elasticity, an

-with a central passage (37) through which the lever arm (30) extends in the mounted state.

10. The application device (100) according to claim 6, 7, 8 or 9, characterized in that the application head (15) has a pressure connection (38) which is arranged on the side of the membrane (34) facing away from the chamber (10).

11. The coating apparatus (100) according to any of the preceding claims 6 to 10, characterized in that one of the following is used

Electromagnetic system

Pneumatic type

-piezoelectric actuator

As a driver (20).

12. The coating apparatus (100) according to any of the preceding claims 6 to 11, characterized in that the coating head (15) is thermally decoupled from the drive (20).

13. The application apparatus (100) according to any one of the preceding claims 6 to 12, characterized in that the arrangement of the lever arm (30), the movable element (11) and the membrane suspension (33) with the membrane (34) is chosen such that the opening or closing movement (P) of the movable element (11) is in anti-phase with the movement (P1) of the second end (32) of the lever arm (30).