METHOD AND DEVICE FOR FILLING SEALING CAPS

Description

[0001] The present invention relates to a method for filling sealing caps (seal caps) and a corresponding automated device.

[0002] In the aircraft industry, rivets or rivet heads are typically coated with a sealant (sealant) or, when cured, a seal cap (sealant cap) to seal them or protect them from corrosion. The sealant is typically applied manually, for example, using hand-held cartridge guns. WO 2014 / 201188 A1 describes an improved method for applying sealant to the back of fasteners.

[0003] As an alternative, sealing caps made from sealant that have already hardened can be used, which are offered in the corresponding contour of the rivet or rivet head. These hardened sealing caps can then be reused in a variety of ways: On the one hand, the hardened sealing caps can be filled with fresh sealant and frozen to prevent the sealant from reacting. Shortly before use, the caps are thawed and are then ready for use. However, this process has the disadvantage that the sealing caps filled with frozen sealant have a limited storage life, must first be conditioned before use, and there is also a risk of condensation. A further disadvantage lies in the logistics chain, which requires rapid transport and the provision of freezers.

[0004] Alternatively, the sealing caps can also be manually filled with sealant directly before use using a cartridge gun and then processed. However, this method cannot guarantee even filling of the sealing caps, as they cannot be weighed during this process step. The injected quantity may therefore be over- or under-dosed. This procedure is also very time-consuming and cumbersome, as the cartridge gun and sealant cap must be handled simultaneously, and the cap must be fitted promptly.

[0005] The objective of the present invention was therefore to provide a method for filling the sealing caps that does not have the aforementioned disadvantages. Filling the sealing caps with sealant should be particularly time-saving, yet high-quality, and at the same time result in cost reduction.

[0006] The underlying object of the present invention is achieved by the method according to claim 1. Preferred embodiments are specified in the subclaims. The method according to the invention can be used to fill already cured sealing caps. The filled sealing compound can be frozen as described above for use after a certain storage period, or, as also explained above, filled shortly before the sealing cap is fitted. Preferably, the sealing caps are not frozen but filled shortly before fitting, thereby reducing costs because no freezers need to be provided and no cold chain needs to be maintained.

[0007] In the method according to the invention for filling sealing caps (seal caps), the filling of the sealing caps is carried out automatically. The positioning of the filling unit and / or the positioning of the cured sealing caps by means of movement in the XYZ direction, as well as the filling of the sealing caps, are carried out automatically, and the cured sealing caps are positioned on a carrier plate. This results in a time saving of up to 100% compared to the conventional manual filling of the sealing caps.

[0008] The automation of the filling process is, for example, software-controlled, by moving either the sealing caps located on the carrier plate and / or the filling unit of the device from which the sealant is poured into the sealing cap in the X, Y, or Z directions. Preferably, a robot or a similar device with an XYZ travel path is used for this purpose, which allows either the carrier plate together with the sealing caps and / or the filling unit to be moved automatically to fill the sealant when correctly positioned.

[0009] In a further preferred embodiment, the method according to the invention can also comprise the automated placement after filling of the sealing cap.

[0010] The underlying object of the present invention is also achieved by the device according to claim 10.

[0011] According to the invention, such a device or such a robot comprises a filling unit with which the sealing compound is filled into the sealing cap; a carrier plate on which the cured sealing caps are located; a travel unit with which either the filling unit and / or the carrier plate can be moved, preferably via a corresponding motorization; and a control unit with which the movement of the filling unit and / or the carrier plate and the filling are regulated, wherein the travel unit and the filling unit are each controlled by the control unit.

[0012] An example of such a robot can be found in the Fig. 1 to 3 shown.

[0013] Fig. 1 : View of the robot from above. The base of the robot, which serves to attach the support plate, is visible here.

[0014] Fig. 2 : Front view of the robot

[0015] Fig. 3 : Side view of the robot. The filling unit here includes a cartridge with mixed sealant attached to a dispensing head.

[0016] The filling unit preferably comprises a dispensing unit with which the sealant is pressed from a corresponding container into the sealing cap. The device to be used according to the invention comprises, in particular, a cartridge dispensing unit with a compressed air drive or servo drive as the filling unit. Cartridges filled with finished sealant are inserted into the dispensing unit, from which the sealant is then pressed out during filling. However, it is also possible for the dispensing unit to comprise a mixing container into which the two components are poured from two different lines and then mixed to produce the sealant directly before filling.

[0017] The cartridge ejection unit preferably has a servo drive. The cartridge is filled with the sealant and is ejected by a piston controlled by the servo drive. The servo drive is particularly suitable for two different cartridge sizes commonly used in the aircraft industry. This eliminates the need for an air-assisted pressing unit, allowing the use of compressible sealants (sealants that are not Newtonian fluids and are compressed during ejection).

[0018] In a preferred embodiment of the present invention, the automated device is portable. In this case, the device has dimensions and a corresponding configuration that allow for rapid assembly and disassembly. A portable device allows for assembly directly at the user's location, allowing the user to place the sealing caps on the respective rivet or rivet head without delay.

[0019] The significant increase in process speed through filling using an automated device, for example a suitable robot system, also allows an increase in the cycle rate in aircraft construction if the manual activities involved in filling and fitting the sealing caps are reduced.

[0020] When using a suitable robotic system, the average time for filling a sealing cap with sealant is just 2.5 seconds. In comparison, manual filling takes an average of, for example, ... seconds.

[0021] In a preferred embodiment, the automated device, preferably the robot, can inject the sealing compound into the sealing caps in the arrangement specified by the carrier plate. The sealing caps are mounted on the carrier plate in a freely selectable arrangement. This arrangement of the sealing caps on the carrier plate can either be pre-programmed into the software of the control unit or the control unit can include an optical detection unit, for example, which is capable of determining the position of the other sealing caps during or before filling the sealing caps and controlling them accordingly with the filling unit.

[0022] The number of sealing caps on the carrier plate can be varied within a wide range and depends solely on the size of the sealing cap in relation to the size of the carrier plate. The sealing caps can also be positioned on the carrier plate in such a way that the positioning pattern on the carrier plate resembles or even matches the positioning pattern of the rivets or rivet heads on the actual component. This can make it easier to identify the correct position for the sealing cap to be applied.

[0023] In a preferred embodiment, the robot can inject the sealing compound into the sealing caps in the contour defined by the carrier plate.

[0024] The amount of sealant to be injected depends on the user's requirements and can be specified for each sealing cap according to its geometry and the geometry of the rivet or rivet head. In a preferred embodiment, the standardized amount is stored in a suitable program of the control unit for the respective sealing cap size before filling. Based on this stored data, the automated device, preferably the robot, can then fill the sealing cap with the correct amount.

[0025] This prevents the sealing cap from being over- or under-dosed with too much or too little sealant. At the same time, it also prevents the thawing sealing caps from forming condensation with mixed sealant.

[0026] The extrusion or filling speed of the sealant or the filling time can preferably be adjusted via corresponding settings on the device, preferably the robot. The filling speed is preferably adapted to the properties of the sealant, in particular the viscosity, the flow properties and / or the thread break. Appropriate settings are intended to achieve an optimized filling pattern (height and silhouette of the filling in the sealing cap) that meets the user's requirements, in particular the surface requirements of the filling. In a preferred embodiment, the surface of the sealant filling is flat or level in cross-section and does not have a tapered elevation, which occurs, for example, when the speed at which the filling unit lifts off the filling is not matched to the thread break properties of the sealant.

[0027] The curing speed of the sealant in the sealing cap can also be adjusted by selecting a faster sealant, which is not possible when using frozen sealing caps.

[0028] According to a first particularly preferred embodiment, the sealing caps are plastic caps for sealing connecting elements in aircraft construction, which predominantly consist of at least one high-performance polymer and have a dielectric strength of at least 10 kV / mm according to DIN IEC 60243.

[0029] These plastic caps are filled with a sealing compound that has a high energy absorption capacity and at least one filler selected from the group consisting of hollow fillers filled with gas and / or air. The plastic caps and the sealing compound are cohesively bonded together.

[0030] Such sealing caps function as combined protection against fuel and hydraulic oil, especially that based on tributyl phosphate, as well as against lightning strikes and can be manufactured and applied economically.

[0031] The following definitions apply: When the term "high-performance polymer" is used here, it refers to homopolymers and copolymers that are characterized by high chemical and temperature resistance.

[0032] The fact that the "plastic caps [...] consist predominantly of at least one high-performance polymer" means that they may still contain less than 50% by weight of other components that are not high-performance polymers.

[0033] The term "the plastic caps and the sealing compound are cohesively bonded together" is to be understood in the sense that the filled sealing compound and the at least one high-performance polymer cannot be separated non-destructively or do not separate under the conditions normally encountered during aircraft operation.

[0034] The at least one high-performance polymer of the plastic caps is in particular selected from the group consisting of polyvinylidene fluoride (PVDF), polysulfone (PSU), polyphenylene sulfone (PPSU), polyetheretherketone (PEEK), polyimide (PI), polyamideimide (PAI), polybenzimidazole (PBI), polyetherimide (PEI) and polyphenylene sulfide (PPS).

[0035] The sealing compound filled into the plastic caps is preferably based on polysulfide and / or polythioether. It is particularly preferably a polysulfide and / or a polythioether in combination with manganese dioxide, an isocyanate compound, an isocyanate prepolymer, and / or an epoxy compound as a hardener.

[0036] The use of gas- and / or air-filled hollow fillers has the advantage of energy-absorbing properties due to their microcellular nature. These hollow fillers are preferably microballoons.

[0037] With such sealing caps, precise filling - as made possible by the present invention - is particularly important, since expelled sealing compound is not resistant to hydraulic oil.

[0038] According to a second, particularly preferred embodiment, the sealing caps are those produced with nozzles described in EP 2 586 537 A1. These nozzles for applying sealants have a bell-shaped or hood-shaped nozzle tip and a clamping ring on the injection side of an elongated nozzle element. Injection can be performed manually or with automated sealant injection machines.

Claims

1. A method for filling seal caps, which comprises filling the seal caps automatedly by means of a device which comprises - a filling unit with which the sealant is filled into the seal caps; - a support plate on which the cured seal caps are located; - a displacement travel unit with which either the filling unit and / or the support plate can be moved; and - a control unit with which the movement of the filling unit and / or of the support plate and the filling are regulated, wherein the control unit comprises an optical recognition unit, wherein the filling unit comprises a cartridge extrusion unit with servo drive and wherein the positioning of the filling unit and / or the positioning of the cured seal caps by means of movement in XYZ direction as well as the filling of the seal caps take place automatedly.

2. The method according to claim 1, wherein filling is carried out using a device with XYZ travel, preferably a robot with XYZ travel.

3. The method according to claim 1 or 2, wherein the robot injects the sealant into the seal caps in the contour dictated by the support plate.

4. The method according to any of the preceding claims, wherein, prior to filling, the amount of sealant to be injected for the particular seal cap size is stored in a suitable program of the control unit.

5. The method according to any of the preceding claims, wherein the filling rate is adapted to the properties of the sealant.

6. The method according to any of the preceding claims, wherein the seal caps are plastic caps for the sealing of connecting elements in aircraft construction, said caps consisting predominantly of at least one high-performance polymer and having a DIN IEC 60243 breakdown strength of at least 10 kV / mm and being filled with a sealant which has high energy absorbency and also comprises at least one filler selected from the group consisting of hollow filling bodies filled with gas and / or air, the plastic caps and the sealant being joined cohesively to one another.

7. The method according to claim 6, wherein the at least one high-performance polymer of the plastic caps is selected from the group consisting of polyvinylidene fluoride (PVDF), polysulfone (PSU), polyphenylene sulfone (PPSU), polyetheretherketone (PEEK), polyimide (PI), polyamideimide (PAI), polybenzimidazole (PBI), polyetherimide (PEI), and polyphenylene sulfide (PPS).

8. The method according to claim 6 or 7, wherein the sealant filled into the plastic caps is a sealant based on polysulfide and / or polythioether.

9. The method according to any of claims 6 to 8, wherein the hollow filling bodies filled with gas and / or air are microballoons.

10. A device for performing the method according to any of claims 1 to 9, wherein the device comprises: - a filling unit with which the sealant is filled into the seal cap; - a support plate on which the cured seal caps are located; - a displacement travel unit with which either the filling unit and / or the support plate can be moved; and - a control unit with which the movement of the filling unit and / or of the support plate and the filling are regulated, wherein the control unit comprises an optical recognition unit, wherein the filling unit comprises a cartridge extrusion unit with servo drive.