Method and device for filling seal caps

Abstract

Described herein is a method for filling seal caps and a corresponding automated device for filling seal caps. The method for filling seal caps includes carrying out the filling of the seal caps using an automated process, wherein positioning a filling unit and/or positioning the seal caps by means of movement in an XYZ coordinate system as well as filling the seal caps is automated, and wherein the seal caps are positioned on a support plate.

Claims

1. A method for filling seal caps for sealing connecting elements in aircraft construction, the method comprising: filling the seal caps with sealant using an automated process, wherein positioning a filling unit and/or positioning the seal caps by means of movement in an XYZ coordinate system as well as filling the seal caps is automated; and wherein the seal caps are positioned on a support plate in a positioning pattern that corresponds to a positioning pattern of the connecting elements to be sealed; and wherein the seal caps are plastic caps comprising at least one high-performance polymer 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), the sealant is a sealant based on polysulfide and/or polythioether and the plastic caps and the sealant are joined cohesively to one another.

2. The method according to claim 1, wherein filling is carried out using a device able to travel in the XYZ coordinate system.

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

4. The method according to claim 1, wherein, prior to filling, an amount of sealant to be injected for a particular seal cap size is stored in a suitable program of a control unit.

5. The method according to claim 3, wherein a filling rate is adapted to properties of the sealant.

6. The method according to claim 1, wherein the plastic caps consist predominantly of the at least one high-performance polymer and having a DIN IEC 60243 breakdown strength of at least 10 kV/mm and the sealant 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.

7. The method according to claim 6, wherein the hollow filling bodies filled with gas and/or air are microballoons.

8. The method according to claim 2, wherein the device able to travel in the XYZ coordinate system is a robot able to travel in the XYZ coordinate system.

9. A method for filling seal caps for sealing connecting elements in aircraft construction, the method comprising: filling the seal caps with sealant using an automated process, wherein positioning a filling unit and/or positioning the seal caps by means of movement in an XYZ coordinate system as well as filling the seal caps is automated; and wherein the seal caps are positioned on a support plate in a positioning pattern that corresponds to a positioning pattern of the connecting elements to be sealed; wherein the seal caps are plastic caps consisting predominately of at least one high-performance polymer and having a DIN IEC 60243 breakdown strength of at least 10 kV/mm, wherein the high performance polymer 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); wherein the sealant has high energy absorbency, is a sealant based on polysulfide and/or polythioether and also comprises at least one filler selected from the group consisting of hollow filling bodies filled with gas and/or air; and wherein the plastic caps and the sealant are joined cohesively to one another.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) An example of a corresponding robot is illustrated in FIGS. 1 to 4.

(2) FIG. 1: View of the robot from diagonally above. Visible here is the base of the robot, which serves for the fastening of the support plate.

(3) FIG. 2: Front view of the robot.

(4) FIG. 3: Side view of the robot. The filling unit here comprises a cartridge with mixed sealant, which is fastened on a metering head.

(5) FIG. 4: Schematic diagram of the top section view of a filled seal cap in accordance with an exemplary embodiment.

(6) FIG. 5 is an illustration of a method for filling seal caps in accordance with an exemplary embodiment.

(7) FIG. 6 is a block diagram of the control unit in accordance with an exemplary embodiment.

DETAILED DESCRIPTION

(8) Referring to FIGS. 1-4, in one aspect of the invention, a device or robot 10 has a base 11, a support plate 12, a filling unit 13, a displacement travel unit 14 and a control unit 15. The filling unit 13 fills sealant 16 into a seal cap 17. The support plate 12 is fastened to base 11 and a seal cap 17 is positioned on the support plate 12. The filling unit 13 includes an extrusion unit 18, which has a metering head 19, such as a compressed-air drive or servo drive. The extrusion unit 18 may be a cartridge extrusion unit as shown in FIGS. 1-3. A cartridge 20 with mixed sealant 16 may be inserted into the extrusion unit 18 and fastened to the metering head 19. In one aspect, the cartridge extrusion unit 18 includes a piston 21.

(9) A filled seal cap 17 is shown in FIG. 4. The sealant 16 may include a filler, such as hollow filling bodies filled with gas and/or air. In one aspect, the hollow filling bodies filled with gas and/or air are microballoons 22.

(10) The filling unit preferably comprises an extrusion unit with which the sealant is pressed from a corresponding container into the seal cap. The device of the invention to be used comprises more particularly a cartridge extrusion unit with compressed-air drive or servo drive as filling unit, and cartridges filled with ready-made sealant are inserted into the extrusion unit, from which cartridges the sealant is then extruded on filling. It is, however, also possible for the extrusion unit to comprise a mixing vessel in which, from two different lines, the two components are filled in and subsequently mixed, so that the sealant is produced directly prior to filling.

(11) The cartridge extrusion unit preferably has a servo drive. In this case the cartridge is filled with the sealant and is pressed out by means of a piston which is controlled via the servo drive. With particular preference the servo drive is suitable for two different cartridge sizes which are commonplace within the aircraft industry. As a result, there is no need for an air-assisted pressing unit, and so compressible sealants (sealants which are not newtonian fluids and which are compressed during extrusion) can be used.

(12) In one preferred embodiment of the present invention, the automated device is portable. In this case, then, the device has dimensions and a configuration such as to allow a rapid set-up and take-down of the device. A portable device allows set-up directly at the premises of the user, who is able consequently to mount the seal caps on the respective rivet or rivet head without a time delay.

(13) The significant increase in operating speed as a result of filling by means of an automated device, such as a suitable robot system, for example, also allows an increase in the cycle rate in aircraft construction if the activities performed manually during the filling and mounting of the seal caps are reduced.

(14) Where a suitable robot system is used, the average time for the filling of a seal cap with sealant is, for example, only 2.5 seconds. In comparison to this, in the case of manual filing, the procedure is time-consuming.

(15) The automated device, preferably the robot, is able to inject the sealant, in one preferred embodiment, into the seal caps in the arrangement dictated by the support plate. The seal caps in this case are fastened in a freely selectable arrangement on the support plate, this arrangement of the seal caps on the support plate either having been programmed into the software of the control unit beforehand, or the control unit comprising a—for example—optical recognition unit which is capable, during or before the filling of the seal caps, of determining the position of the other seal caps and directing them correspondingly with the filling unit. FIG. 6 provides a block diagram of the control unit in accordance with an exemplary embodiment. With reference to FIG. 6, the control unit 15 includes an optical recognition unit 150.

(16) The number of seal caps on the support place can be varied within a wide range and is dependent only on the size of the seal cap in relation to the size of the support plate. The seal caps can also be positioned on the support plate in such a way that the positioning pattern on the support plate is similar to or indeed corresponds to the positioning pattern of the rivets or rivet heads on the actual component. This makes it easier to recognize the correct position for the seal cap to be applied. FIG. 5 provides an illustration of a method for filling seal caps in accordance with an exemplary embodiment. With reference to FIG. 5, seal caps are filled with sealant using an automated process 100, a filling unit and/or seal caps are positioned by means of automated movement in an XYZ coordinate system 200 and the seal caps are positioned on a support plate in a positioning pattern corresponding to a positioning pattern of connecting elements to be sealed 300.

(17) The robot is able to inject the sealant, in one preferred embodiment, into the seal caps in the contour dictated by the support plate.

(18) The amount of sealant to be injected is dependent on user requirements and may be specified for each seal cap in accordance with its geometry and with the geometry of the rivet or rivet head. In one preferred embodiment, prior to the filling, the standardized amount for the particular size of seal cap is stored in a suitable program of the control unit. On the basis of these stored data, the automated device, preferably the robot, is then able to fill the respectively correct amount into the seal cap.

(19) As a result, over and/or underdosing of the seal cap with too little or too much sealant is avoided. At the same time, the formation of condensation by the thawing seal caps with sealant prepared by mixing is prevented as well.

(20) The extrusion rate or filling rate of the sealant, or the filling time, can be adjusted preferably via corresponding adjustments on the device, preferably the robot. The filling rate is preferably adapted to the properties of the sealant, particularly the viscosity, the rheology and/or the stringing. Through such adjustments, the aim is to achieve an optimized filling pattern (height and silhouette of the filling in the seal cap) that meets the requirements of the user, particularly the surface requirements imposed on the filling. In one preferred embodiment, the surface of the sealant filling has a planar or level cross section and does not have an elevation which ends in a point and which is formed, for example, when the speed at which the filling unit lifts from the filling is not matched to the stringing properties of the sealant.

(21) The cure rate of the sealant in the seal cap may also be adapted by selecting a faster sealant, something which is not possible, in contrast, when using deep-frozen seal caps.

(22) According to a first, especially preferred embodiment, the seal caps are plastic caps for the sealing of joining 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.

(23) These plastic caps are filled with a sealant which has a high energy absorbency and also with 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 here are joined cohesively to one another.

(24) Seal caps of this kind function as combined protection against fuel and hydraulic oil, especially that based on tributyl phosphate, and also against lightning strike, and can be produced and applied economically.

(25) The following definitions are to apply here:

(26) Reference presently to “high-performance polymer” is to homopolymers and copolymers which are distinguished by high chemical stability and thermal stability.

(27) The concept of the “plastic caps [ . . . ] consisting predominantly of at least one high-performance polymer” means that they may also include an amount of less than 50 wt % of other constituents which are not high-performance polymers.

(28) The phrase “the plastic caps and the sealant are joined cohesively to one another” should be understood to mean that the filled-in sealant and the at least one high-performance polymer cannot be parted from one another without destruction or do not part under the conditions which are usual in the operation of an aircraft.

(29) The at least one high-performance polymer of the plastic caps is selected more particularly 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).

(30) The sealant filled into the plastic caps is preferably a sealant based on polysulfide and/or polythioether. With particular preference it is a polysulfide and/or a polythioether in combination with manganese dioxide, an isocyanate compound, an isocyanate prepolymer and/or an epoxide compound as hardener.

(31) The use as fillers of hollow filling bodies filled with gas and/or air has the advantage that the microcellular character of such bodies endows them with an energy-absorbing activity. The hollow filling bodies filled with gas and/or air are preferably microballoons.

(32) With seal caps of this kind, precise filling—of the kind enabled by the present invention—is particularly important, since expelled sealant is not resistant to hydraulic oil.

(33) According to a second especially preferred embodiment, the seal caps are caps produced using nozzles described in EP 2 586 537 A1. These nozzles for the application of sealants have a nozzle tip in bell or cowl form, and a clamping ring of the injection side of an elongated nozzle element. Injection may take place manually or with automated sealant injection machines.

(34) With seal caps of this kind, precise filling—as enabled by the present invention—is likewise particularly important.