Application device and method for applying a plastic to a component surface

Abstract

The invention relates to an application device (10) for applying a plastic (12) to a component surface (14), comprising a nozzle (18) which includes a material channel (20) and at least one gas channel (22), wherein the material channel (20) is configured to guide the plastic (12) to be applied to the component surface (14) in an application direction (24), and the at least one gas channel (22) is configured to guide a gas flow (34) in the application direction (24), whereby the gas flow (34) flowing out of the gas channel (22) circumferentially surrounds a material flow (30) of the plastic (12) flowing out of the material channel (20), and with a control device (38) which is configured to trigger a laminar flow of the gas flow (34) in the gas channel (22) during the application of the plastic (12) to the component surface (14) and to stop the gas flow when the application is stopped. The application is intended to trigger a turbulent outflow of the gas stream (34) from the gas channel (22).

Description

[0001] The invention relates to an application device for applying a plastic to a component surface and a method for applying a plastic to a component surface.

[0002] DE 10 2004 031 031 A1 discloses a device for applying highly viscous materials, preferably adhesives and sealants that flow when heated, to an oily workpiece surface. The highly viscous material, with a viscosity of more than 80 Pa.s, is propelled through an application nozzle at a pressure of at least 700 bar and sprayed onto the workpiece surface in a free jet.

[0003] Furthermore, US 3,210,008 A discloses a spray coating device for applying a coating of charged particles of a material to an object. The spray coating device comprises a base body with a liquid outlet nozzle and a gas outlet nozzle adjacent to the liquid outlet nozzle for atomizing the liquid exiting the liquid outlet nozzle. Furthermore, the spray coating device comprises a substantially cup-shaped, electrically conductive spray nozzle, which forms a mixing chamber for the atomized liquid particles in order to electrically charge them statically before they enter the atmosphere. The spray coating device further comprises a limited, electrically conductive jet opening leading into the atmosphere, whereby the charged liquid particles can be projected onto the object to be coated.

[0004] Furthermore, DE 10 2020 103 232 A1 discloses a method for applying particles to a substrate, wherein a quantity of particles is provided in a gas stream at an inlet end of a device. Furthermore, the gas stream is accelerated toward an outlet end of the device, heating the gas stream. The particles are focused onto an axis oriented parallel to the gas stream, and during focusing, the particles are accelerated and heated by the accelerated gas stream. The outlet end of the device is directed toward the substrate, in particular toward the surface of the substrate.

[0005] The object of the present invention is to provide a solution which enables a precise application of a plastic to a component surface without drawn threads of the plastic or splashes of the plastic adhering to the component surface.

[0006] This object is achieved according to the invention by the subject matter of the independent claims. Further possible embodiments of the invention are disclosed in the subclaims, the description, and the figures. Features, advantages, and possible embodiments presented in the description for one of the subject matter of the independent claims are to be regarded at least analogously as features, advantages, and possible embodiments of the respective subject matter of the other independent claims, as well as any possible combination of the subject matter of the independent claims, optionally in conjunction with one or more of the subclaims.

[0007] The invention relates to an application device for applying a plastic to a component surface. The component surface is, in particular, part of a motor vehicle component. This plastic can be used to close or seal an opening in the component surface. For example, the plastic can be a seam sealing material. In this case, MS polymer can be applied to the component surface as a plastic. MS polymer sealants, also known as "modified silicone" or "hybrid" sealants, comprise a modified silane polymer as a base instead of a synthetic polymer base of silicone or a urethane-based polymer system used in polyurethane sealants. MS polymers are silane-modified polyether-based polymers. They react with atmospheric moisture or a booster to create a strong adhesive bond.

[0008] The application device comprises a nozzle which has a material channel and at least one gas channel. The material channel is designed to guide the plastic to be applied to the component surface as a material flow in an application direction. The at least one gas channel is designed to guide a gas flow in the application direction. This means that in the material channel and the at least one gas channel, the material flow and the gas flow flow at least substantially parallel to one another, since both the material flow and the gas flow flow in the application direction within the respective channels. The gas flow flowing out of the gas channel circumferentially surrounds the material flow of the plastic flowing out of the material channel. This means that in a cross-section which runs perpendicular to the application direction, the gas flow forms a ring around the material flow.By enclosing the material flow in this ring-shaped manner, the gas flow can prevent plastic from spraying out of the material flow laterally and thus radially with respect to the application direction, whereby plastic splashes on the component surface can be particularly effectively avoided.

[0009] The application device further comprises a control device configured to trigger a laminar flow of the gas stream in the gas channel during application of the plastic to the component surface. Furthermore, the control device is configured to trigger a turbulent outflow of the gas stream from the gas channel upon completion of application. Completion of application means that no further application of plastic to the component surface takes place. This means that, during application, the plastic is applied to the component surface by means of the application device, and in order to limit the area of ​​the component surface to which plastic is applied, no further material is applied to the component surface, thus completing the application process.Changing the laminar flow of the gas stream to a turbulent outflow of the gas stream from the gas channel can be achieved, for example, by adjusting the flow velocity of the gas stream in the gas channel. Alternatively or additionally, an obstacle, such as a flap or a pin, can be moved into the gas channel, thereby generating turbulence in the gas stream.

[0010] During the application of the plastic to the component surface, the laminar gas flow, which extends in a ring around the material flow, acts as a barrier for the plastic to prevent plastic splashing onto the component surface outside of the application area of ​​the component surface intended for the application of the plastic. The turbulent outflow of the gas flow from the gas channel at the end of the application process allows any thread of plastic material created due to the end of the plastic application to be entrained by the turbulent gas flow and thrown back into the material channel. This makes it particularly effective to prevent this pulled plastic thread from sticking to the component surface. As a result, the application device can ensure that the plastic can be applied to the component surface with particular precision and only in the specified application area.

[0011] In a possible development of the invention, it is provided that the gas channel is arranged concentrically to the material channel and encloses the material channel in a ring shape. This means that the application device comprises in particular exactly one material channel and exactly one gas channel, wherein the gas channel extends exactly once around the material channel in the radial direction. The ring-shaped design of the gas channel and the concentric arrangement of the gas channel to the material channel ensure that the material flow flowing out of the material channel is annularly enclosed over its entire circumference by the gas flow flowing out of the gas channel. In this way, the gas flow delimits an area in which the material flowing out of the nozzle is located, whereby splashes of the material on the component surface can be particularly effectively avoided.Furthermore, the annular and concentric arrangement of the gas channel relative to the material channel ensures that the gas flow is evenly distributed around the material flow, whereby the material flow flowing out of the application device is evenly blocked over its circumference by the gas flow. This minimizes any influence of the gas flow on the direction of movement of the material flow.

[0012] In a further possible embodiment of the invention, it is provided that the control device is configured to reduce a speed of the material flow in the material channel upon termination of the application, in particular to stop the material flow in the material channel. For this purpose, the control device can, for example, be configured to control a valve device or a conveying device for the material flow in the material channel, so that no further material is pushed into the material channel upon termination of the application of the plastic to the component surface. As a result, further flow of the material flow out of the material channel is prevented by reducing the speed of the material flow in the material channel, in particular by stopping the material flow in the material channel.This ensures that the plastic is only applied to the component surface in the specified application area, and that other areas of the component surface that must be kept free of the plastic are also reliably kept free of the plastic. This allows, for example, the application device to reliably and precisely apply the plastic to the component surface.

[0013] In a further possible embodiment of the invention, it is provided that the material channel and the gas channel are separated from one another by an inner nozzle wall in a radial direction running perpendicular to the application direction. As a result, the gas flow can be deflected at a lower edge of the inner nozzle wall as it flows out of the gas channel, in particular towards the material flow. When the application device is used as intended, the lower edge of the inner nozzle wall is aligned towards the component surface. Thus, the lower edge of the inner nozzle wall forms a boundary of the inner nozzle wall in the application direction towards the component surface. The turbulent outflow of the gas flow from the gas channel is triggered by the deflection of the gas flow at the lower end of the inner nozzle wall.This allows a pulled thread of the material stream to be thrown back into the material channel at the end of the application process, once further outflow of the material stream from the material channel is prevented. During the application of the plastic, the laminar flow can be redirected toward the material stream, in particular by adjusting the flow direction of the gas stream such that the gas stream flowing out of the gas channel flows at an angle to the material stream flowing out of the material channel in the application direction. This ensures that the gas stream flows reliably along a radial outer side of the material stream.

[0014] This ensures that the gas flow effectively prevents individual splashes of material from being released from the material flow.

[0015] In this context, it can be provided in particular that an outer nozzle wall is provided which bounds the gas channel radially outwards and projects axially beyond the inner nozzle wall in the application direction. In this case, the outer nozzle wall projects beyond the inner nozzle wall on the side of the nozzle at which the gas flow and the material flow flow out of the nozzle during intended use. In other words, the outer nozzle wall projects beyond the inner nozzle wall on a side of the application device which, during intended use, faces the component surface. This ensures that the gas flow flowing out of the gas channel is deflected towards the material flow at the lower end of the inner nozzle wall, since in the region in which the gas flow is deflected, the gas flow continues to be bounded radially outwards by the outer nozzle wall.The risk of the gas flow being diverted from the material flow and thus of the material flow not being reliably blocked radially by the gas flow can thus be particularly well avoided.

[0016] In a further possible embodiment of the invention, it is provided that the application device comprises a so-called pressure booster, which is designed to generate a pressure pulse of the gas flow. The pressure booster generates the pressure pulse of the gas flow by increasing the flow velocity of the gas flow in the gas channel for a predetermined period of time, starting from an initial value. This triggers the turbulent outflow of the gas flow from the gas channel. Furthermore, it is provided that the control device is designed to control the pressure booster. The pressure booster is a double-piston pressure intensifier, which can compress air in particular. If the pressure booster is pressurized with compressed air, internal check valves can automatically ensure a pressure build-up on the secondary side. This makes it possible to increase the output pressure to up to twice the value of the input pressure.The pressure booster enables the turbulent outflow of the gas stream from the gas channel by generating the pressure pulse. Thus, no moving parts of the application device are required to achieve the turbulent outflow of the gas stream. As a result, the application device is designed to be particularly robust, thus ensuring a particularly long service life.

[0017] The invention further relates to a method for applying a plastic to a component surface, in particular a motor vehicle component. In the method, it is provided that an application device, in particular an application device as already described in connection with the application device according to the invention, is used for applying the plastic. In this case, a laminar flow of the gas stream in the gas channel is triggered by means of the control device of the application device during the application of the plastic to the component surface. Upon completion of the application, a turbulent outflow of the gas stream from the gas channel is triggered by means of the control device. This turbulent outflow of the gas stream from the gas channel can be achieved in particular by adjusting the flow velocity of the gas stream in the gas channel.In this process, the laminar gas flow, which radially encloses the material stream flowing out of the nozzle of the application device over its entire circumference, is blocked off laterally during application of the plastic to the component surface in order to minimize the risk of plastic splashing onto the component surface. When application of the plastic to the component surface is stopped, further outflow of the material stream from the material channel is prevented and the gas stream is triggered to flow turbulently out of the gas channel. As a result of the stopped material flow, any pulled threads of the plastic are torn off, carried along by the turbulent gas flow and thrown back into the material channel by the turbulent gas flow. This is a particularly effective way of preventing threads of the plastic from adhering to the component surface.

[0018] In a possible development of the invention, it is provided that, in order to generate a pressure pulse for triggering the turbulent outflow of the gas flow from the gas channel, the velocity of the gas flow in the gas channel is increased from an initial value for a predetermined period of time and is reduced again to end the pressure pulse. This pressure pulse can be generated, for example, by means of a pressure booster. The pressure pulse ensures that turbulence is generated in the gas flow, in particular by at least partially deflecting the gas flow at a lower end of the inner nozzle wall that radially delimits the gas channel. Since the adjustment of the turbulent outflow of the gas flow from the gas channel is generated by the pressure pulse, moving parts for generating turbulence in the gas flow are not necessary. These moving parts could have a certain latency with regard to responding to control signals.By means of the pressure pulse, the turbulent outflow of the gas stream from the gas channel can be generated particularly quickly, whereby any pulled threads can be reliably thrown back into the material channel.

[0019] In a further possible embodiment of the invention, MS polymer is applied as a plastic to the component surface using the application device. MS polymers are permanently elastic and thus withstand repeated movements without the quality of a bond being impaired by cracks, tears, or detachments. Furthermore, MS polymers exhibit a particularly broad adhesion profile and thus adhere particularly well to many different materials, such as metal or plastic. This ensures reliable, permanent adhesion of the plastic to the component surface.

[0020] In a further possible embodiment of the invention, it is provided that an opening in the component surface is closed using the plastic. For example, a seam in or on the component surface can be sealed using the plastic. Because the described method enables the plastic to be applied to the component surface with particular precision, it can be achieved that only the opening on the component surface to be sealed is sealed using the plastic, and areas of the component surface that are to be kept free are reliably kept free of the plastic. The method enables reliable, precise sealing of the opening on the component surface.

[0021] Further features of the invention may emerge from the claims, the figures, and the description of the figures. The features and combinations of features mentioned above in the description, as well as the features and combinations of features shown below in the description of the figures and / or in the figures alone, can be used not only in the respective combinations specified, but also in other combinations or on their own, without departing from the scope of the invention.

[0022] The drawing shows: Fig. 1 a schematic sectional view of an application device during application of a plastic to a component surface; and Fig. 2 a schematic sectional view of the application device when the application of the plastic to the component surface is completed.

[0023] In the figures, identical and functionally identical elements are provided with the same reference numerals.

[0024] In the Fig. 1 and Fig. 2, an application device 10 is shown in a schematic sectional view. The application device 10 is intended to apply a plastic 12 to a component surface 14 of a component, in this case a motor vehicle component 16. The plastic 12 is an MS polymer, by means of which openings in the component surface 14 are to be sealed. For this purpose, a patch made of the plastic 12 can be applied to the area of ​​the component surface 14 to be sealed using the application device 10. Adjacent to the area to be sealed, the motor vehicle component 16 can have interfering contours or a neighboring component which should not be wetted with the plastic 12.

[0025] The application device 10 comprises a nozzle 18. This nozzle 18 has a material channel 20 and a gas channel 22 radially surrounding the material channel 20 on the outer circumference. The gas channel 22 surrounds the material channel 20 in an annular manner. In this case, the gas channel 22 is arranged concentrically to the material channel 20. The nozzle 18 is configured to apply the plastic 12 to the component surface 14 in an application direction 24. The material channel 20 and the gas channel 22 run with their respective longitudinal extension directions parallel to the application direction 24. An axial direction A of the nozzle 18, in turn, runs parallel to the longitudinal extension direction of the respective channels 20, 22 and thus to the application direction 24. A radial direction R of the nozzle 18 is perpendicular to the axial direction A.

[0026] The nozzle 18 has an inner nozzle wall 26 and an outer nozzle wall 28 that surrounds the inner nozzle wall 26 at least in an axial length section on the outer circumference. The inner nozzle wall 26 separates the material channel 20 and the gas channel 22 from each other in the radial direction. The outer nozzle wall 28 radially surrounds the gas channel 22 on the outer circumference. This means that the material channel 20 and the gas channel 22 are each delimited in the radial direction by the inner nozzle wall 26 and the outer nozzle wall 28. As shown in the Fig. 1 and Fig. 2, the outer nozzle wall 28 protrudes on a lower side of the nozzle 18 facing the component surface 14 when the application device 10 is used as intended. This means that the outer nozzle wall 28 is longer on the lower side in the axial direction than the inner nozzle wall 26.

[0027] The material channel 20 is configured to guide the plastic 12 to be applied to the component surface 14 in the form of a material flow 30 in the application direction 24. The material flow 30 can flow out of the nozzle 18 via an outlet opening 32. The gas channel 22 is configured to guide a gas, in this case air, in the form of a gas flow 34 in the application direction 24. If the plastic 12 is applied to the component surface 14 by means of the application device 10, which in Fig. 1, the material flow 30 flows out of the nozzle 18 via the outflow opening 32. The gas flow 34 flowing out of the gas channel 22 surrounds the material flow 30 on the circumference. When the plastic 12 is applied to the component surface 14, the gas flow 34 flows out of the nozzle 18 in a laminar manner through the outflow opening 32. Due to the inner nozzle wall 26 being axially set back in the region of the outflow opening 32 compared to the outer nozzle wall 28, the gas flow 34 can be deflected at a lower edge facing the outflow opening 32, which is arranged on the front side of the material channel 20. As a result, the gas flow 34, after it has left the gas channel 22, flows obliquely towards the material flow 30, as a result of which the gas flow 34 flows around the material flow 30 on the circumference.The gas flow 34 fulfills a blocking function and prevents the release of material droplets from the material flow 30, which could detach from the material flow 30 in the radial direction R. This allows a clear lateral edge of the plastic 12 applied to the component surface 14 to be achieved and unwanted plastic splashes on the component surface 14 can be particularly well avoided.

[0028] In Fig.2 shows the application device 10 during the completion of the application of the plastic 12 to the component surface 14. To complete the application of the plastic 12, the speed of the material flow 30 in the material channel 20 is reduced, in particular reduced to 0. This means that the material flow 30 no longer flows out of the nozzle 18 via the outlet opening 32. To prevent threads of the plastic 12 pulled due to the completion of the application of the plastic 12 from settling on the component surface 14, it is provided that the gas flow 34 flowing out of the gas channel 22 is turbulent upon completion of the application. This means that a turbulent outflow of the gas flow 34 from the gas channel 22 is triggered upon completion of the application. In order to trigger the turbulent outflow of the gas stream 34, the application device 10 can have a pressure booster 36 schematically marked with a box.The pressure booster 36 is configured to generate a pressure pulse of the gas stream 34 by increasing the flow velocity of the gas stream 34 in the gas channel 22 for a predetermined period of time from an initial value by means of the pressure booster 36, thereby triggering the turbulent outflow of the gas stream 34 from the gas channel 22. In this case, air, in particular oil-free dried air, is used as the gas stream 34 to avoid wetting problems. The pressure pulse for converting the laminar flow into the turbulent flow can, for example, be as short as 100 ms. As a result of the pressure pulse, a flow separation of the gas stream 34 can be caused. The turbulent gas flow can be deflected around the lower inner nozzle wall 26 and thus flow at least partially toward the material channel 20 in a direction opposite to the application direction 24 or at least partially into the material channel 20.The turbulent gas flow 34 is designed to entrain any pulled threads of the plastic 12 and propel them into the material channel 20. This can minimize the risk of pulled threads adhering to the component surface 14. By propelling any pulled threads into the material channel 20, the material of this thread can be reapplied during the next application.

[0029] The application device 10 further comprises a control device 38, schematically indicated by a box, which is configured to trigger the laminar flow of the gas stream 34 from the gas channel 22 during the application of the plastic 12 to the component surface 14 and to trigger the turbulent outflow of the gas stream 34 from the gas channel 22 upon completion of the application. For this purpose, the control device 38 can be configured to control the pressure booster 36.

[0030] The described invention is based on the finding that MS polymer, due to its material properties, can result in stringing at the end of an application. However, one requirement may be to create short, targeted applications of the MS polymer without overspray into an area of ​​the component surface 14 not to be coated with the MS polymer. Due to limited installation space, a selective application of the MS polymer to the component surface 14 may be necessary, and external wetting of sensitive surfaces or areas of adjacent components to be coated may be critical.

[0031] To meet these requirements, the application device 10 is provided with a multi-channel application nozzle, in this case nozzle 18. This multi-channel application nozzle can be used to generate a variable volume flow of the plastic 12 and thus enables the reliable coating of a predetermined application area of ​​the component surface 14.

[0032] Sealing air in the outer nozzle ring, which is the gas flow 34, makes it possible to avoid overspray or to generate a sharply cut surface of the plastic 12 applied to the component surface 14. A resulting threading is avoided by changing the flow via changing the volume flow of the gas flow 34, whereby the laminar flow of the gas flow 34 is converted into a turbulent flow.

[0033] The described application device 10 makes it possible to particularly effectively prevent overspray and pulled threads of the plastic 12 adhering to the component surface 14, even at a high application pressure of the plastic 12 onto the component surface 14, which may be necessary to ensure adhesion. In particular, during application, the pressure in the gas channel 22 is greater than the pressure with which the material stream 30 from the nozzle 18 is applied to the component surface 14.

[0034] When applying the plastic 12 to the component surface 14, a distance of at least 2 mm between a lower edge of the nozzle 18 and the component surface 14 is set. In particular, no contact of the application device 10 with the component surface 14 is provided.

[0035] Overall, the invention shows how a targeted sealing of areas at risk of corrosion can be implemented with particular precision. List of reference symbols 10 Application device 12 plastic 14 Component surface 16 Motor vehicle component 18 nozzle 20 material channel 22 Gas duct 24 Application direction 26 inner nozzle wall 28 outer nozzle wall 30 Material flow 32 Outlet opening 34 Gas flow 36 pressure boosters 38 Control device A axial direction R radial direction QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2004 031 031 A1

[0002] US 3 210 008 A

[0003] DE 10 2020 103 232 A1

[0004]

Claims

[1] Application device (10) for applying a plastic (12) to a component surface (14), comprising a nozzle (18) which comprises a material channel (20) and at least one gas channel (22), wherein the material channel (20) is designed to guide the plastic (12) to be applied to the component surface (14) in an application direction (24), and the at least one gas channel (22) is designed to guide a gas flow (34) in the application direction (24), whereby the gas flow (34) flowing out of the gas channel (22) circumferentially encloses a material flow (30) of the plastic (12) flowing out of the material channel (20), and comprising a control device (38) which is designed to trigger a laminar flow of the gas flow (34) in the gas channel (22) during the application of the plastic (12) to the component surface (14) and Completion of the application triggers a turbulent outflow of the gas stream (34) from the gas channel (22). [2] Application device (10) according to claim 1, characterized by that the gas channel (22) is arranged concentrically to the material channel (20) and encloses the material channel (20) in a ring shape. [3] Application device (10) according to claim 1 or 2, characterized by that the control device (38) is designed to reduce a speed of the material flow (30) in the material channel (20) in order to end the application, in particular to stop the material flow (30) in the material channel (20). [4] Application device (10) according to one of the preceding claims, characterized by in that the material channel (20) and the gas channel (22) are separated from one another by an inner nozzle wall (26) in a radial direction running perpendicular to the application direction (24), whereby the gas flow (34) can be deflected at a lower edge of the inner nozzle wall (26) when flowing out of the gas channel (22), in particular towards the material flow (30). [5] Application device (10) according to claim 4, characterized by that an outer nozzle wall (28) is provided which radially outwards delimits the gas channel (22) and projects axially beyond the inner nozzle wall (26) in the application direction (24). [6] Application device (10) according to one of the preceding claims, characterized by that a pressure booster (36) is provided which is designed to generate a pressure pulse of the gas flow (34) by increasing a flow velocity of the gas flow (34) in the gas channel (22) for a predetermined period of time starting from an initial value, whereby the turbulent outflow of the gas flow (34) from the gas channel (22) is triggered, and that the control device (38) is designed to control the pressure booster (36). [7] Method for applying a plastic (12) to a component surface (14), in which the plastic (12) is applied to the component surface (14) by means of an application device (10) according to one of the preceding claims, wherein a laminar flow of the gas stream (34) in the gas channel (22) is triggered by means of the control device (38) during the application of the plastic (12) to the component surface (14) and a turbulent outflow of the gas stream (34) from the gas channel (22) is triggered when the application is terminated. [8] Method according to claim 7, characterized by in that, in order to generate a pressure pulse for triggering the turbulent outflow of the gas flow (34) from the gas channel (22), the speed of the gas flow (34) in the gas channel (22) is increased for a predetermined period of time starting from an initial value and is lowered again to end the pressure pulse. [9] Method according to claim 7 or 8, characterized bythat MS polymer is applied as a plastic (12) to the component surface (14) by means of the application device (10). [10] Method according to one of claims 7 to 9, characterized by that an opening in the component surface (14) is closed by means of the plastic (12).

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