Patent ID: 12233607

DETAILED DESCRIPTION

FIG.1depicts how a double curvature single skin inflatable body is rigidized and smoothened in a desired shape by means of a plurality of link tapes1, each link tape section bonded with a bond line2to each opposing membrane3and4. The membranes are joined at their contours5,6to create an air tight chamber. As the double curvature of the membranes have a continuously changing inclination, each individual link tape1will have bond lines2at a local inclination angle relative to the tape center line. The link tapes1in this figure are arranged in a corrugating fashion, with excess lengths of link tape left between two consecutive bond lines on a membrane, which eliminates the need for cutting each link tape section after bonding to one of the opposing membranes.

FIG.2depicts such inclination angles α and β relative to the link tape center line. These angles may be higher or lower than 90°. Note that link tape1shown here is cut to length at both cut lines7prior to or after bonding. Such cutting can be at a right angle to the link tape center-line, particularly if that is deemed a necessary simplification for automated manufacturing.

InFIGS.3A, B and C three different alignment schemes for pluralities of bond lines2on sections of membrane with two sections of contour5and6are depicted.FIG.3Adepicts a longitudinal alignment, which would be useful on for instance an inflatable float of a water craft, as the longitudinal pattern would minimize hydrodynamic flow disturbances. Another benefit of choosing such alignment is the increment of longitudinal stiffness by applying the combined total of all panel stiffnesses of all link tapes in a useful orientation.FIG.3Bdepicts a transverse alignment of link tape bond lines2, which is suitable for, for instance, an airfoil as found in ram-air inflatable kites, or manifold inflatable wings that provide higher rigidity. As the orientation of the bond lines aligns with the air flowing over such airfoils, the aerodynamic flow disturbance is minimized. In order to add rigidity to such inflatable airfoils, external stiffeners such as struts, or bridles, can be added. Internal stiffeners can also be added, for instance by means of tubular air chambers with elevated pressure levels.FIG.3Cdepicts a mixed bond line2orientation pattern, which adds to omnidirectional rigidity to an inflatable body that can be built in a process according to the invention.

FIG.4depicts a partial cross section of an inflatable body with each link tape1cut to length, similar to the link tape1depicted inFIG.2, prior to or after bonding. It is known to persons skilled in the art that cutting a plurality of link tapes1to length prior to bonding is highly unpractical and not well suited for automation. It should be understood that the amount of link tapes1will be well into the hundreds, if not thousands, in most inflatable bodies built according to the invention. However, in an automated manufacturing process, cutting link tape1to length after bonding is possible with a tape positioning and bonding means provided with an automatic cutter.

The corrugating link tapes1as depicted inFIG.5are suitable for inflatable bodies built according to the invention with no or minor local inclination of the opposing membranes, in the plane of the link tape1. If said inclination is too high, the bond lines of the link tape1to the opposing membranes are unevenly tensioned, causing peak stresses in said bond lines and loss of smoothness in the inflated membrane surfaces. Further, corrugating link tape1as depicted inFIG.5allows for speedy assembly relative to the variations shown inFIGS.4and6as there's only one bond line2per section of link tape1. It has however a lower bond line count causing relatively low smoothness of the resulting membrane surface upon inflation. This corrugating link tape further increases the pulling load on the bond lines2, as two link tapes1are pulling the same bond line2.

FIG.6depicts a partial cross section of an inflatable body with corrugating sections of link tape, in a version with double bond lines that allow for both an inclination of the opposing membranes3,4in the link tape plane, and angular variation in the bond lines in the plane of a membrane, with each section of excess link tape8between two bond lines2on one of the opposing membranes allowed to fold away from said membrane, as further laid out inFIG.7.

FIG.7shows that such a section of excess link tape8can fold unevenly with one edge9folding out higher than its opposing side10, as said section8likely has a trapezoid shape due to the local inclination of the opposing membranes3,4as depicted inFIG.2by angles α or β, or angular variation of the bond lines2in the plane of a membrane as depicted inFIG.3C.

FIG.8depicts an inflatable body according to the invention having a first air tight chamber11having circular sections joined to a second air tight chamber12having single or double curvature opposing membranes3,4held in shape by a plurality of internal link tapes1. Air chambers11and12may be pressurized differently, for instance circular sectioned chamber11can be pressurized at a significantly higher pressure as the resulting hoop loads of such pressure are running tangential to its membrane13. Due to the high pressure, a rigid structural element is formed by such chamber11that, in combination with the second air tight chamber12having single or double curvature, a rigid inflatable body is formed with a desired single or double membrane curvature. Multiple differently pressurized air tight chambers can be assembled to build rigid inflatable bodies like hulls, wings, rotors and sails.FIG.8further depicts a number of link tapes14that partly wrap around a circular section of air chamber11membrane13, with their lengths precisely adjusted to provide a smooth outer surface of the sections of membranes3and4of air chamber12adjacent to air chamber11, upon inflation of both air chambers.

FIG.9depicts a portion of a membrane3or4printed with contour curves15,16and a plurality of coded position marks17for bond lines2. Contour curve15defines the cutting line of the membrane, while contour curve16defines a join line of the membrane portion, for instance to join with one or more adjacent membrane portions to form a composed membrane3or4that approximates a double curvature face of an inflatable body according to the invention, or to join to an adjacent membrane portion if the desired inflatable body size exceeds that of stock material, or the span of a manufacturing means. Two contour curves16on opposing membranes3or4can also be joined to form an edge of an inflatable body according to the invention, for instance the leading edge of a wing, or the gunwale of an inflatable hull. Coded position marks17, here depicted as computer readable bar-codes combined with human readable numbers, are in this figure combined with a dotted line that indicate the exact position of the bond lines2belonging to each code. Human readable codes can be desired for quality assurance purposes, or manual assembly or repair.

As the codes are printed on the membrane material, a robotic arm fitted with means for positioning or bonding link tape, and an optical sensor capable of reading a coded position mark and the position and orientation of a bond line2belonging to said code, can return information to the robotic arm control system to aid exact positioning and bonding of a link tape1to a membrane3or4.

FIGS.10and11depict two steps of a tape positioning head18, as part of a means for a manufacturing process according to the invention, equipped with a dual anvil19, for feeding and positioning link tape1to bond line2locations on opposing membranes3and4, working with a bond activating head20as yet another part of said manufacturing means, present on the outside of the assembly of link tape12and membranes3and4to assemble an inflatable body according to the invention.

In the step depicted inFIG.10, a bond line2is being created by holding exactly positioned link tape1against membrane3by one of the two portions of a dual anvil19and a bond activating head20, which is then activated. Exact positioning in this case involves locating and aligning of a bond line2on both link tape1and membrane3, in accordance with the local inclination α fromFIG.2. Location and alignment may be assisted by an interplay of coded position marks17, an optical sensor and a computer controlled robotic arm as described in the aboveFIG.9. In order to assure bond activating head20assumes the exact position relative to the membrane3and tape positioning head18, said optical sensor is preferably fitted to bond activating head20as it is situated on the outside of the inflatable body being assembled, therefore having its view unobstructed by already bonded link tapes. A second interplay of proximity sensors and computer controlled robotic arms can steer tape positioning head18and bond activating head20to their exact locations and orientations to form a bond line2with the desired exact location on both membrane3and link tape1.

Bond activation may occur by applying heat through thermal transfer, friction or vibration energy to fuse material in a welding process, or by activating a chemical bond curing reaction by heat or UV light, or another process, not limiting the scope of the invention. Even though piercing options are present by way of stitching of riveting, it must be noted that piercing the membranes3,4, may introduce leaks in the inflatable body, which, for inflatable bodies operating at higher pressures, is highly unwanted. Especially for lower pressure operation, such as ram-air wings, stitching can be considered. In case stitching is chosen as bonding method, tape positioning head18and bond activation head20can respectively be fitted with needle and bobbin assemblies to form a sewing means.

As tape positioning head18moves to the next bond line location as a next step depicted inFIG.11, it approximately makes a half turn in the direction that has the link tape feed side of the tape positioning head away from the previously assembled link tape, as indicated by arrow A, which as a result presents the other of the two portions of the dual anvil19to the membrane4. During said movement, an exact length of link tape1is fed through the dual anvil, and the dual anvil assumes an angle β, as depicted inFIG.2, relative to the link tape1center line. Now bond activation head20is present on the outside of membrane4to work with tape positioning head18to form a new bond line2. To persons skilled it the art it is obvious that adding a second bond activation head on a third robotic arm, with each bond activation head dedicated to one of the membranes3or4, considerably improves assembly speed.

FIG.12depicts essential parts of a motorized link tape positioning head18with pinch rollers21and dual anvil19with motorized inclination angle adjustment. It must be noted that in this figure, the chassis is largely removed to show said essential parts.

The pinch rollers21are driven by a feed motor22and synchronized in opposing rotation directions by a synchronizing assembly, herein depicted as a set of gears23. As it is of great importance that the pinch rollers have minimal to no slippage on the link tape1, the roller material, surface texture, hardness and compression have to be securely matched with the tape surface to avoid said slippage. The dual anvil19consists of two flat portions to each side of a tape slot24of sufficient width to let the link tape1through freely. In case of an assembly method as depicted in the previousFIGS.10and11each flat portion of dual anvil19, here shown with cross hatches, is alternately used to create a bond line2as the tape positioning head18makes a half turn when moving from one opposing membrane to the other. Dual anvil19is further tiltable to adapt a desired inclination by means of a motorized angle adjustment assembly, here shown as a worm gear25driving a connecting rod26connected to one side of dual anvil19. Dual anvil19is tiltably mounted on the same chassis part27that encases the pinch rollers.

The flat portions of dual anvil19may be provided with a knurled surface, that, in concert with a matching knurl on bond activation head20, improves bond line2strength and/or activation speed. Link tape1is guided into tape positioning head18by an angled guide28, and is along arrow B continuously supplied from a reel located away from the tape positioning head18. By entering the tape feed angular to tape head18the tape and its guides are not obstructing the movement of tape positioning head18when it is working to assemble link tape1between opposing membranes3and4.

AsFIG.12has no mention of scale, for viewers it may be difficult to assess the width and thickness of link tape1. These will vary widely between different applications of the inflatable bodies built according to the invention. A very light pressurized inflatable body according to the invention with a pressure of only 0.1 bar, such as a kite, may for instance have link tapes as narrow as 5 millimeters and a very light composition of only 30 Denier. An inflatable body according to the invention operated at a much higher pressure of over 1 bar, for instance a stand up paddle board, can have link tapes as wide as 25 mm and a 250 Denier composition. It should be noted that fabric composition for both link tapes along with the density of the link tape distribution can be optimized to the desired mix for acceptable surface smoothness, weight and manufacturing costs. Conclusively, different tape positioning head18designs can be made to match a variety of link tape1properties. It can be desired to apply multiple widths and compositions of link tape1in a single assembly. In such cases multiple tape positioning heads can be present on a manufacturing means according to the invention.

FIG.13provides and overview of a manufacturing means for automated assembly of an inflatable body, showing membranes3,4, suspension29and feed tracks30, as well as a robotic arm31fitted with a link tape positioning head18, link tape feed reel32and a partially assembled plurality of link tapes. The embodiment depicted here has robotic arm31and link tape reel32mounted to a car movable along a track34running across the assembly area of link tape1to membrane3,4. The suspension29of membranes3and4in this embodiment is an arrangement of elastic elements and cars running inside feed tracks.

As one can see from this figure, the orientation of the assembly area is arranged such, that link tapes already assembled sag between the opposing membranes3,4, therewith minimizing the chance of obstructing the assembly process.

FIG.14depicts a cross sectional view of the manufacturing means fromFIG.13, further showing a robotic arm35fitted with a bond activation means20ready to engage in bonding a section of link tape to one of the opposing membranes, and another robotic arm36fitted with a bond activation means20in idle state. Both robotic arms35,36are mounted to cars to run in tracks37parallel to track34.

FIG.15depicts an enlarged detail view of the manufacturing means fromFIG.13, of the link tape positioning head18doing its work. Tape managing means38are in place to deliver the tape from reel32to the tape positioning head18unfolded and wrinkle free.