Device and method for spraying multi-component plastic materials - Patents.com

Abstract

The present invention relates to a device (1) for applying a multi-component plastic to a substrate, the device (1) comprising a dosing valve (10) controllable by compressed air as pressure medium and having a first valve inlet (11) for a first component (2), a second valve inlet (12) for a second component (3) and a valve outlet (17), a static spray mixer (50) comprising a tubular mixer housing (53) extending along a longitudinal axis and having a valve end (54) and a distal end (55), a mixing element (57) arranged in the mixer housing (53) for producing a component mixture, and a spray sleeve (51) arranged at the distal end (55) of the mixer housing (53) and having an inlet (52) for a pressurized spray medium. The present invention provides that the mixer housing (53) and the mixing element (57) are made of plastic and are an integral part that is inserted into the mixer housing (53). Furthermore, the present invention relates to a method in which the device (1) is used.

Description

[Technical field]

[0001] The present invention relates to a device for spraying a substrate with a multi-component plastic and a method for using said device. [Background technology]

[0002] From US 5,255,892 a dosing valve (metered quantity valve, metered quantity dispensing valve) is known which has a first valve inlet for a first component and a second valve inlet for a second component. Each valve inlet is assigned a needle, via which a passage to the valve outlet can be opened or closed. The needle is connected to a control piston, which is part of the cylinder unit of the dosing valve and can be pressurized with compressed air. The dosing valve can also be used for dispensing highly viscous plastic components. The dosing valve is preferably part of a system with which a multi-component plastic can be sprayed onto a substrate in large quantities over a long period of time.

[0003] A static spray mixer can be connected to the valve outlet of the dosing valve, which has a tubular mixer housing extending along a longitudinal axis. The mixer housing has a valve-side end connectable to the valve outlet and a distal end with an outlet nozzle. A mixing element is arranged in the mixer housing, which mixes the first and second components exiting separately from the valve outlet of the dosing valve as homogeneously as possible. Thereby, the two components pass through the mixing element from the valve-side end along the longitudinal axis to the distal end, whereby a homogeneous mixture of the first and second components is generated in the mixer housing. An atomizing sleeve is arranged at the distal end of the mixer housing. The atomizing sleeve has an inlet for a pressurized atomizing medium. This atomizing medium can be, for example, compressed air. To achieve the most homogeneous and continuous application of the multi-component plastic, the atomization makes it possible to apply the mixture of the two components exiting from the outlet nozzle to the substrate in the form of a spray jet or a spray mist. Summary of the Invention [Problem to be solved by the invention]

[0004] The desired goal of a uniform application with a constant layer thickness depends on many factors. For example, with several-component or two-component viscous mixtures, a satisfactory result can only be achieved if at least one of the two components is preheated, which makes the application of multi-component plastics laborious. The pressure at which the two components leave the dosing valve and the pressure of the spray medium can be varied within wide limits, but varying the pressure does not always lead to the desired result.

[0005] The invention is based on the object of providing a device for spraying multi-component plastics, by means of which viscous multi-component plastics can be sprayed easily and homogeneously onto a substrate.

[0006] The object underlying the present invention is solved by the combination of features according to the claims. Examples of embodiments of the invention can be taken from the subclaims of claim 1. [Means for solving the problem]

[0007] According to the invention, it is provided that the mixer housing and the mixing element are made of plastic, the mixing element being an integral element which is inserted into the mixer housing. The mixing element may be an injection-molded part, which on the one hand allows good mixing of highly viscous substances such as sealants, two-component foams or two-component adhesives due to the efficient mixing structure, and on the other hand allows a compact and material-saving design of the static spray mixer. It has been found that such a spray mixer combination, which is usually designed for one-time use, in conjunction with a dosing valve or system suitable for spraying large quantities over a long period of time leads to good results in terms of homogeneity of the plastic layer and layer thickness. Furthermore, it has been found that the service life of plastic spray mixers using plastic mixing elements is sufficiently good. Static mixers with integral mixing elements made of plastic are known, for example, from EP 0 749 776 and EP 0 815 929.

[0008] In one embodiment, the cross section of the mixer housing perpendicular to the longitudinal axis and the cross section of the mixing element perpendicular to the longitudinal axis are each rectangular, preferably square. The cross section of the mixer housing does not have to be rectangular or square over the entire length of the mixer housing, but only in the part where the mixing element is housed. For example, the mixer housing may have a rectangular or square cross section in the middle part, while the valve end and the distal end are substantially rotationally symmetric. Such spray mixers are sold, for example, by the Sulzer group.

[0009] In one embodiment, the atomizing sleeve may be fitted to the distal end along the longitudinal axis of the mixer housing. A snap connection may be provided between the atomizing sleeve and the mixer housing. The snap connection ensures that the atomizing sleeve is fixed to the distal end in the axial direction. Furthermore, the snap connection may also have a sealing effect that prevents the compressed air supplied through the inlet of the atomizing sleeve from unintentionally leaking out. In addition to the snap connection, another seal may be provided. It should be noted that in principle there are also other ways of fixing the atomizing sleeve to the distal end (e.g. screw connection or bayonet lock).

[0010] Between the valve outlet and the valve end of the spray mixer, a separate adapter may be provided for removably attaching the spray mixer to the dosing valve, which allows the spray mixer to be replaced, for example, by a new spray mixer. This can be done in a simple manner if the spray sleeve can also be easily pulled out of the distal end of the mixer housing.

[0011] The adapter may include an adapter housing, a valve connection means for releasably attaching to the dosing valve, and a mixer connection means for releasably attaching a spray mixer to the adapter. Thus, in addition to simply replacing the spray mixer, it is also possible to remove the adapter from the dosing valve and connect, for example, a different type of spray mixer to the dosing valve. The valve connection means and / or the mixer connection means may be integrally formed in the adapter housing. In one embodiment, the valve connection means and the adapter housing are separate parts.

[0012] The adapter housing is preferably made of metal, with preferred materials herein being stainless steel (e.g., 304SS) or aluminum.

[0013] The adapter housing can have a recess to accommodate the diaphragm of the dosing valve. The diaphragm is part of the valve outlet of the metering system and ensures that the components leaving the dosing valve first meet in the spray mixer for further mixing.

[0014] In one embodiment, the adapter housing defines a straight channel for the first component and a straight channel for the second component such that the components can pass through the adapter housing without deflection and associated flow resistance.

[0015] A further object of the present invention to provide a method for spraying a multi-component plastic onto a substrate is solved by the combination of features as claimed in claim 10. The multi-component plastic is preferably a polyurea, which may be solvent-free and free of volatile organic components (VOC). Such polyureas are sold as two-component adhesives, for example under the trademark LINA888. With LINA888 polyurea, no heating of one or both components and / or the substrate is required. The curing of LINA888 is almost weather-independent, resulting in reproducible and reliable bond strengths. In one embodiment the components are mixed in a 2:1 ratio. [Brief description of the drawings]

[0016] The invention will now be explained in more detail with reference to the embodiments shown in the drawings. [Figure 1] FIG. 1 shows a schematic structure of a device according to the present invention. [Diagram 2] FIG. 2 shows a perspective view of an adapter for a device according to the present invention. [Figure 3A] FIG. 3 (see FIGS. 3A-3D) shows a different view of the adapter of FIG. [Figure 3B] FIG. 3 (see FIGS. 3A-3D) shows a different view of the adapter of FIG. [Figure 3C] FIG. 3 (see FIGS. 3A-3D) shows a different view of the adapter of FIG. [Figure 3D] FIG. 3 (see FIGS. 3A-3D) shows a different view of the adapter of FIG. [Figure 4] FIG. 4 shows a dosing valve for a device according to the invention. [Diagram 5] FIG. 5 shows an atomizing mixer for a device according to the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] FIG. 1 shows a schematic representation of a device for spraying a multi-component plastic, the device being indicated generally as 1. The device 1 comprises a dosing valve 10, an adapter 30 and a spray mixer 50, which are shown unassembled for clarity. The device 1 is used to mix a first component 2 and a second component 3 to form a multi-component plastic, which is then applied in the form of a spray 4 to a substrate, not shown. The substrate is for example a flat metal plate. The multi-component plastic can for example be a polyurea adhesive.

[0018] The dosing valve 10 has a first valve inlet 11 for a first component 2 and a second valve inlet 12 for a second component 3. Compressed air 5 is used to control the dosing valve 10 and is supplied to a cylinder unit 13 of the dosing valve 10. The compressed air 5 may be used to control the flow rate of the first component 2 and the flow rate of the second component 3 through the dosing valve 10. In FIG. 1, two ports 14 of the cylinder unit 13 are shown as an example of multiple ports through which compressed air may enter and exit the cylinder unit.

[0019] Starting from the dosing valve 10, the first component 2 and the second component 3 are fed via the adapter 30 to the spray mixer 50. The components 2, 3 are guided in separate paths in the dosing valve 10 and in the adapter 30. Only in the spray mixer 50 are the components 2, 3 brought together and intensively mixed there. To generate the spray 4, the mixer 50 has a spray sleeve 51 with an inlet 52 for compressed air 5. The supply of compressed air 5 for the spray sleeve 51 or the control unit of the compressed air 5 for the dosing valve 10 are not further shown in FIG.

[0020] Figures 2 and 3 show one embodiment of the adapter 30. Figure 3A shows a side view of the adapter 30. Figure 3D shows a cross-sectional view along line dd in Figure 3A. Figure 3B shows the adapter 30 from the front, and thus the side facing the spray mixer 50. Figure 3C shows the adapter 30 from the back.

[0021] The adapter 30 has an adapter housing 31, a valve connection means 32 in the form of a swivel nut 33, and a mixer connection means 34. The adapter 30 can be connected to a dosing valve 10 by the valve connection means 32. The mixer connection means 34 is used to connect an atomizing mixer 50 to the adapter 30.

[0022] The adapter 30 has a first adapter inlet 35 for the first component 2 and a second adapter inlet 36 for the second component 3. Between the adapter inlets 36, 37 is a groove-like recess 49. Within the adapter housing 31 a first straight channel extends from the first adapter inlet 35 to the first adapter outlet 37 and a second straight channel extends from the second adapter inlet 36 to the second adapter outlet 38.

[0023] The mixer connection means 34 includes an end plate 39 having a raised portion 41 on which the adapter outlets 37, 38 are located. The end plate 39 is defined by a rim 40 having four rim portions 40a, 40b, 40c, 40d. The rim portions 40a and 40c are parallel to each other and extend in a straight line. Each of the rim portions 40a, 40b is formed with a pocket 42 of rectangular cross section. Each pocket 42 also has a small recess 43 at the bottom of the pocket. The rim portions 40b and 40d represent an annular portion of a circle, the center of which is on the central axis of the adapter 30 (which also represents the central axis of the swivel nut 33). Each of the annular portions or annular rim portions 40b, 40d extends over an angular range of approximately 90°. The straight rim portions 40a, 40c can also be seen as flattened circular cover plates.

[0024] Each of the annular rim portions 40b, 40d defines a trailing or trailing edge 44 that is rearwardly engageable by a rotatable bayonet lock cover (not shown) attached to the spray mixer. The mixer connection means may therefore also be referred to as part of a bayonet connection.

[0025] The swivel nut 33 has a conical part 45 and a cylindrical part 46, on the inside of which an internal thread 47 is provided, and on the outside of which gripping ribs 48 are provided. The mutually parallel gripping ribs 48 extend in the axial direction and are evenly distributed around the circumference. With the help of the gripping ribs 48, the swivel nut 33 can be screwed by hand onto the corresponding external thread with sufficient force. The adapter housing 31 and the end plate 39 are preferably manufactured in one piece from metal, although the swivel nut can also be a separate plastic injection-molded part.

[0026] FIG. 4 shows an example of a dosing valve 10. The cylinder unit 13 in FIG. 4 has four ports 14 for compressed air, by means of which the dosing valve 10 can be controlled. A lubricating nipple 15 is provided between the valve inlets 11, 12 and the cylinder unit 13, through which lubrication of a control piston displaceably mounted in the housing of the dosing valve 10 is possible. A funnel-shaped mouthpiece 16 forms the valve outlet 17 and provides openings 18, 19 for each of the components 2, 3. Between the openings 18, 19 is provided a trapezoidal partition 20, which engages in a recess 49 when the adapter 30 is connected. FIG. 4 also shows an external thread 21, which cooperates with an internal thread of the swivel nut 33 of the adapter 30.

[0027] FIG. 5 shows an embodiment of a spray mixer 50. The spray mixer has an elongated tubular mixer housing 53 with a valve or adapter end 54 and a distal end 55. Between the valve end 54 and the distal end 55, the mixer housing 53 has a central housing part 56 serving to receive a mixing element 57. The mixing element 57 is preferably a one-piece injection molded plastic part and can therefore be manufactured at low cost. The mixing element 57 defines a plurality of sequentially connected and interconnected chambers through which the components 2, 3 flow. The mixing element preferably has a square cross section. The central housing part 56 therefore also has a square cross section.

[0028] The components 2, 3 are intensively mixed while their flows pass through the mixing element 57. At the distal end 55, the already mentioned spray sleeve 51 with the inlet 52 is arranged. The spray sleeve 51 thereby constitutes an outlet nozzle 58, from which the mixture of the first component 2 and the second component 3 emerges. The mixture is atomized by the compressed air 5 in the spray sleeve 51, forming a spray jet 4 of the previously mixed multi-component plastic.

[0029] A connecting means 59 is provided at the valve end 54 and connects the mixer housing 53 to the adapter 30. The connecting means 59 has two pins 60 suitable for engaging in the pockets 42 of the adapter 30. When connected, the spray mixer 50 and the adapter 30 cannot rotate relative to each other. Although not shown in FIG. 5, a bayonet locking cover is attached to the mixer housing 53 and can be pressed against the valve end 54 to connect the spray mixer 50 to the adapter 30. For this purpose, the bayonet locking cover is provided with an undercut that can rotate 90° to engage with the rear edge 44 of the adapter 30. [Explanation of symbols]

[0030] 1 Device 2 First component 3. Second Component 4 Spray Jet 5. Compressed Air 10 Dosing valve 11 First valve inlet 12 Second valve inlet 13 Cylinder unit 14 Connection 15 Grease nipple 16 Mouthpiece 17 Valve outlet 18 Openings 19 Opening 20 Partition 21 External thread 30 Adapter 31 Adapter housing 32 Valve connection means 33 Swivel nut 34 Mixer connection means 35 First adapter inlet 36 Second adapter inlet 37 First adapter outlet 38 Second adapter outlet 39 Cover plate 40 Rim (rim portions 40a, 40b, 40c, 40d) 41 Ridge 42 Pocket 43 Recess 44 Trailing Edge 45 Cone section 46 Cylindrical section 47 Internal Thread 48 Gripping Rib 49 Deep 50 Spray Mixer 51 Spray Sleeve 52 Entrance 53 Mixer housing 54 Valve end / adapter end 55 Distal end 56 middle row 57 Mixed elements 58 Exit nozzle

Claims

1. A device (1) for coating a substrate with a multi-component plastic, A dosing valve (10) is controllable by compressed air as a pressure medium and has a first valve inlet (11) for the first component (2), a second valve inlet (12) for the second component (3), and a valve outlet (17), A static spray mixer (50) comprising a tubular mixer housing (53) extending along its longitudinal axis and having a valve-side end (54) and a distal end (55), a mixing element (57) disposed within the mixer housing (53) to produce a component mixture, and a spray sleeve (51) located at the distal end (55) of the mixer housing (53) and having an inlet (52) for a pressurized spray medium. Equipped with, Device (1), wherein the mixer housing (53) and the mixing element (57) are made of plastic, and the mixing element (57) is an integrated component inserted into the mixer housing (53).

2. The cross-section of the mixer housing (53) perpendicular to the longitudinal axis and the cross-section of the mixing element (57) perpendicular to the longitudinal axis are both rectangular. The device (1) according to claim 1.

3. The spray sleeve (51) is attachable to the distal end (55) of the mixer housing (53) along the longitudinal axis of the mixer housing (53). The device (1) according to claim 1 or 2.

4. A separate adapter (30) is provided between the valve outlet (17) of the dosing valve (10) and the valve-side end (54) of the spray mixer (50) for detachably attaching the spray mixer (50) to the dosing valve (10). The device (1) according to claim 1 or 2.

5. The adapter (30) comprises an adapter housing (31), a valve connection means (32) for releasably attaching to the dosing valve (10), and a mixer connection means (34) for releasably attaching the spray mixer (50) to the adapter (30). The device (1) according to claim 4.

6. The valve connecting means (32) and / or the mixer connecting means (34) are integrally formed with the adapter housing (31). The device (1) according to claim 5.

7. The adapter housing (31) is made of metal. The device (1) according to claim 5.

8. The adapter housing (31) has a recess (49) for receiving the partition (20) of the dosing valve (10). The device (1) according to claim 5.

9. The adapter housing (31) defines a linear channel for the first component (2) and a linear channel for the second component (3). The device (1) according to claim 5.

10. A method for spraying a multi-component plastic onto a substrate using the device (1) described in claim 1 or 2.

11. The aforementioned multi-component plastic is a polyurea adhesive that does not contain solvents or volatile organic components. The method according to claim 10.

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