Apparatus for applying multi-component viscous material to workpiece

Abstract

The invention relates to a device for applying a multi-component viscous material to a workpiece, comprising a metering unit, which has a number of metering valves corresponding to the number of components of the viscous material and a coupling device, and a mixing unit, which has a mixing tube, the mixing pipe is provided with a material inlet at a first end part and a connecting part which is detachably connected with a connecting device, and is provided with a discharge port for the viscous material at a second end part. And the mixing unit is provided with a mixing structure which is arranged in the mixing pipe and is used for mixing the components when the components are guided to pass through the mixing pipe from the material inlet to the discharge port. According to the invention, a needle valve for releasing and closing the outlet opening is provided, which needle valve has a valve needle extending in a longitudinal direction extending from the material inlet to the outlet opening, which valve needle releases the outlet opening in a release position and closes the outlet opening by abutting against a valve seat in a closed position.

Description

Technical Field

[0001] The invention relates to a device for applying a multi-component viscous material to a workpiece according to the preamble of claim 1 . Background Art

[0002] Such a device is disclosed, for example, by DE102018119838A1. The device is used to apply a viscous material having at least two components to a workpiece, in particular to a vehicle component under production. This known device has a metering unit having a number of metering valves corresponding to the number of components of the viscous material and a coupling device, by means of which the metering unit is detachably connected to a mixing unit. The metering unit meters the components of the viscous material and introduces them into a material inlet on a first end of the mixing unit. The mixing unit has a mixing tube and a mixing structure arranged in the mixing tube, which is used for good mixing of the components when the components are guided through the mixing unit from the material inlet to the discharge outlet on the second end. In particular, the viscous material mixed by the multiple components in the mixing unit is applied to the workpiece in the form of a strip (Raupenform). However, the difficulty here is to accurately define the end point of the material strip. When the metering valve is closed to end the material application, there is still material in the mixing unit that can be discharged from the discharge outlet. Therefore, in order to avoid undesirably extending the applied material strip, the coating device is usually moved back a distance at the end of the material strip so that the leaking material is positioned in the area of ​​the applied material strip by means of this trajectory reversal. However, this measure prolongs the cycle time of the coating device operation. Summary of the invention

[0003] It is therefore an object of the present invention to improve a device of the type mentioned at the outset in such a way that the material cut-off at the outlet can be better defined.

[0004] This object is achieved according to the invention by a device having the features of claim 1. Advantageous developments of the invention are the subject of the dependent claims.

[0005] The invention is based on the idea that the application of material from the outlet opening can be definedly shut off by using a needle valve and closing the outlet opening by the valve needle resting on the valve seat. If the outlet opening is closed by means of the valve needle, no material can escape from the mixing unit, so that the end point of the material application can be much better defined. Therefore, a trajectory reversal is no longer necessary, so that shorter cycle times can be achieved.

[0006] The mixing unit can be a so-called X-grid mixing unit, whose mixing structure includes two groups of diagonal rods, which cross along a crossing line extending transversely to the longitudinal direction. The valve needle then extends through the diagonal rods in the center. In addition, the mixing unit can be a so-called quadro-mixing unit (Quadro-Mischeinheit). However, the mixing structure preferably has an inner tube, which is arranged in the mixing tube and extends in the longitudinal direction. The valve needle then extends through the inner tube and the mixing spiral portion protrudes radially from the inner tube, on which the components flow downward from the material inlet to the discharge port and mix with each other during the flow. In this case, the valve needle preferably extends from the inner tube at the front end of the inner tube facing the valve seat and is guided in a sealed manner at the front end of the inner tube by means of a sealing element. The valve needle is then separated from the viscous material and contacts the viscous material only in the valve seat area. The seal at the front end of the inner tube prevents internal leakage, in particular prevents material from entering the inner tube, and thereby improves the mixing quality and enables a higher material pressure in the mixing unit. In each case, the material inlet of the mixing unit communicates with supply channels of the metering unit, through which the individual components of the viscous material are metered to the mixing unit and which can each be blocked and released by means of one of the metering valves.

[0007] The mixing unit can be manufactured in a conventional manner, in particular in one piece or in multiple pieces by drilling, turning, milling or injection molding methods or a combination of these methods. However, it is advantageous that the mixing unit is manufactured in one piece by means of 3D printing. Different materials can be used here. In particular, the mixing tube and the mixing structure can be made of a first material, preferably a material consisting of polylactide (PLA) or acrylonitrile-butadiene-styrene copolymer (ABS) or at least including them, while the valve seat and the sealing element can be made of different second materials respectively. In particular, ABS can be designed to prevent electrostatic discharge (ESD protection). The valve seat and the sealing element can be made of the same second material or two different materials can be used here.

[0008] The needle valve preferably has a drive unit, in particular a pneumatic drive unit, for moving the valve needle. For this purpose, a motor-driven screw drive, a hydraulic drive or a lifting magnet can also be used. The drive unit can advantageously be detachably connected to the metering unit so that the needle valve can be replaced in a simple manner. Here, the valve needle can be moved into a closed position and into a release position in the opposite direction of the longitudinal direction by means of the drive unit. However, the needle valve can also be configured as a so-called snuffback valve, in which the valve needle can be moved into a release position and into a closed position in the opposite direction of the longitudinal direction by means of the drive unit. The snuffback valve has the advantage that the material located in the valve seat area is not pressed out of the outlet when the valve is closed, but is at least partially pulled back into the outlet, so that the end point of the material application can be better defined.

[0009] In order to better mix the components, the mixing structure can be rotatably accommodated in the mixing tube around an axis of rotation extending in the longitudinal direction. Preferred here is a motor drive of the mixing structure, which is for example carried out via a hollow shaft, through which the valve needle also extends at least partially.

[0010] Advantageously, the valve needle is made of metal or hard metal. Hard metal can be understood as a metal matrix-composite material in which hard materials in the form of particles are combined together by a metal matrix. As hard materials, metal carbides or metal nitrides can be used, such as tungsten carbide, titanium carbide, titanium nitride, niobium carbide, tantalum carbide or vanadium carbide. Metals and especially hard metals are wear-resistant materials. In addition, the valve needle can be manufactured together with the mixing unit by means of 3D printing. This is particularly advantageous when the needle valve is configured as a back-sucking valve, because it is not necessary to introduce the valve needle from the outlet into the mixing unit with great effort. It is also advantageous when the needle valve is configured as a back-sucking valve that the valve needle is configured as a two-piece. The two parts of the valve needle are introduced into the mixing unit from opposite directions and then fixedly connected to each other.

[0011] Advantageously, means are provided for generating a vacuum in the mixing tube. If the mixing tube is kept under vacuum, the risk of material leaking out of the discharge opening is further minimized. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The invention is explained in more detail below with reference to an exemplary embodiment schematically shown in the drawing.

[0013] The attached pictures are as follows:

[0014] Figure 1 An apparatus for applying a viscous material is shown in schematic cross-sectional view;

[0015] Figure 2a , Figure 2b A cross-sectional view is shown for use according to Figure 1 A mixing unit according to a first embodiment of the device and an enlarged view of a part B; and

[0016] Figure 3a , Figure 3b A cross-sectional view is shown for use according to Figure 1 A mixing unit according to a second embodiment of the device and an enlarged view of detail F. DETAILED DESCRIPTION

[0017] The coating device 10 shown in the drawings is used to apply a multi-component viscous material to a workpiece. According to the present embodiment, it is a two-component viscous material, such as an adhesive, which is mixed with two components, namely a base component and a hardener. The coating device has a metering unit 12, which has a supply channel 14 for each component, through which the corresponding component is supplied. Each supply channel 14 can be cut off and released by means of a metering valve not shown in the drawings, so that each component can be metered. In addition, the metering unit 12 has a coupling device 16, on which a mixing unit 20 is detachably fixed. The mixing unit 20 has a mixing tube 22, and a coupling portion 26 is provided on the first end 24 of the mixing tube, and the coupling portion is used to be detachably connected to the coupling device 16. A material inlet 28 is also provided on the first end 24 of the mixing tube 22, and the supply channel 14 leads to the material inlet. In the embodiment shown here, the material inlet 28 has two material inlet channels 30, and one of the supply channels 14 leads to each material inlet channel 30. Of course, this principle can also be applied to coating viscous materials formed by more than two components. In the metering unit 12, a number of supply channels and metering valves corresponding to the number of components are always set, which lead to the material inlet 28, and the material inlet can then also have a number of material inlet channels corresponding to the number of components.

[0018] At the second end 32 of the mixing tube 22, the mixing tube has an outlet 34, from which the viscous material formed by mixing the components is discharged so as to be applied to the workpiece. A mixing structure 36 is provided in the mixing tube 22, which is used to mix the components as evenly as possible on their path from the material inlet 28 to the outlet 34. The valve needle 42 of the needle valve 40 extends in a longitudinal direction 38 extending from the material inlet 28 to the outlet 34. In addition, the needle valve 40 has a pneumatic drive unit 44 that is detachably connected to the metering unit 12, with the aid of which the valve needle 42 can be limitedly moved along and against the longitudinal direction 38. A valve seat 46 is provided on the outlet 34, and the valve needle 42 closes the outlet 34 in the closed position by abutting against the valve seat 46 and releases the outlet in the release position, in which the valve needle is lifted from the valve seat 46. Here, according to Figure 2a , Figure 2b In the first embodiment shown in FIG. , the valve needle 42 moves against the longitudinal direction 38 into the release position and along the longitudinal direction 38 into the closing position. Figure 3a , Figure 3b In the second exemplary embodiment, the needle valve 40 is designed as a suck-back valve 25 , and the valve needle 42 is moved in the longitudinal direction 38 into the release position and against the longitudinal direction 38 into the closing position.

[0019] In both embodiments, the mixing unit 20 has an inner tube 48 arranged in the mixing tube 22 and through which the valve needle 42 extends. A mixing spiral 50 protrudes radially from the inner tube 48, which extends as far as the mixing tube 22 and forms a spiral surface inclined toward the outlet opening 34, through which the components flow out and mix during the outflow. The valve needle 42 protrudes from the inner tube 48 at a front end 52 of the inner tube 48 that faces the outlet opening 34 and is arranged at a distance from the outlet opening. In addition, a sealing element 54 is arranged at the front end 52 of the inner tube 48, which surrounds the valve needle 42 and seals against it, and prevents viscous material from entering the inner tube 48.

[0020] In the present embodiment, the mixing unit 20 is manufactured by 3D printing. The mixing tube 22 and the mixing structure 36 are made of the same material in one piece, in the present embodiment, made of polylactide (PLA) or acrylonitrile-butadiene-styrene copolymer (ABS). The valve seat 46 and the sealing element 54 are usually made of wear-resistant material, but are also integrally formed on the mixing tube 22 or the inner tube 48 by means of 3D printing. The valve needle 42 can also be manufactured together with the 3D printing method in the manufacture of the mixing unit 20, especially metal or hard metal is preferably used as the material. In particular, when the needle valve 40 is configured as a back-sucking valve, it is advantageous to manufacture the valve needle 42 by means of a 3D printing method, because the valve needle 42 cannot be introduced into the mixing unit 20 along the longitudinal direction 38. However, a two-piece design of the valve needle 42 can also be considered, in which a part is introduced into the mixing unit 20 along the longitudinal direction 38 and a part is introduced into the mixing unit 20 via the outlet 34 against the longitudinal direction 38 and then the two parts are fixedly connected to each other. Furthermore, it goes without saying that the present invention also includes such a coating device 10, which includes a mixing unit with other mixing structures. In addition, the mixing structure 36 can also be rotated relative to the mixing tube 22 around its longitudinal center axis.

[0021] In summary, the following can be determined:

[0022] The present invention relates to a device 10 for applying a multi-component viscous material to a workpiece, the device comprising a metering unit 12 and a mixing unit 20, the metering unit having a supply channel 14 for each component, the number of which corresponds to the number of components of the viscous material and can be blocked and released by a metering valve, and having a connecting device 16, the mixing unit having a mixing tube 22, the mixing tube having a material inlet 28 at a first end 24, into which the supply channel leads, and a connecting portion 26 detachably connected to the connecting device 16, and having a discharge port 34 for the viscous material at a second end 32, and the mixing unit having a mixing structure 36 arranged in the mixing tube 22 for mixing the components when the components are guided through the mixing tube 22 from the material inlet 28 to the discharge port 34. According to the invention, a needle valve 40 is provided for opening and closing the outlet opening 34 , which has a valve needle 42 extending in a longitudinal direction 38 from the material inlet 28 to the outlet opening 34 , which opens the outlet opening 34 in a released position and closes the outlet opening by abutting against a valve seat 46 in a closed position.

Claims

1. A device for applying a multi-component viscous material to a workpiece, the device comprising a metering unit (12) and a mixing unit (20), the metering unit having a number of metering valves corresponding to the number of components of the viscous material and a coupling device (16), the mixing unit having a mixing tube (22), the mixing tube having a material inlet (28) and a coupling portion (26) detachably connected to the coupling device (16) at a first end (24) and a discharge port (34) for the viscous material at a second end (32), and the mixing unit having a mixing structure (36) arranged in the mixing tube (22) for mixing the components when the components are guided through the mixing tube (22) from the material inlet (28) to the discharge port (34), characterized in that A needle valve (40) is provided for releasing and closing the outlet (34), the needle valve having a valve needle (42) extending in a longitudinal direction (38) extending from a material inlet (28) to the outlet (34), the valve needle releasing the outlet (34) in a released position and closing the outlet by abutting against a valve seat (46) in a closed position.

2. The device according to claim 1, characterized in that The mixing structure (36) has an inner tube (48) which is arranged in the mixing tube (22), through which the valve needle (42) extends and from which a mixing spiral (50) radially projects.

3. The device according to claim 2, characterized in that The valve needle (42) protrudes from the inner tube (48) at a front end (52) thereof facing the valve seat (46) and is guided at the front end (52) in a sealing manner by means of a sealing element (54).

4. The device according to any one of the preceding claims, characterized in that The mixing unit (20) is manufactured in one piece by means of 3D printing.

5. The device according to any one of the preceding claims, characterized in that The mixing unit (20) comprises different materials, and in particular the mixing tube (22) and the mixing structure (36) are made of a first material and the valve seat (46) and, if appropriate, the sealing element (54) are made of a second material or a plurality of different second materials.

6. The device according to any one of the preceding claims, characterized in that The needle valve (40) has a drive unit (44), preferably a pneumatic drive unit, for moving the valve needle (42).

7. The device according to claim 6, characterized in that The drive unit (44) is detachably connected to the metering unit (12).

8. The device according to claim 6 or 7, characterized in that The valve needle (42) can be moved by means of a drive unit (44) in a longitudinal direction (38) into a closed position and counter to the longitudinal direction (38) into a released position.

9. The device according to claim 6 or 7, characterized in that The valve needle (42) can be moved by means of a drive unit (44) in a longitudinal direction (38) into a release position and in a direction counter to the longitudinal direction (38) into a closing position.

10. The device according to any one of the preceding claims, characterized in that The mixing structure (36) is accommodated in the mixing tube (22) so that it can rotate about a rotation axis extending in the longitudinal direction (38), preferably driven by a motor.

11. The device according to any one of the preceding claims, characterized in that The mixing tube (22) and the mixing structure (36) are made of polylactide (PLA) or acrylonitrile-butadiene-styrene copolymer (ABS).

12. The device according to any one of the preceding claims, characterized in that The valve needle (42) is made of metal or hard metal.

13. The device according to any one of claims 1 to 11, characterized in that The valve needle (42) is produced together with the mixing unit (20) by means of 3D printing.

14. Apparatus according to any one of the preceding claims, characterised in that Means are provided for creating a vacuum in the mixing tube.

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