ROUNDING OF DROP-STITCH ELEMENTS
The invention relates to a drop-stitch element in which at least one adhesive fold (9, 10) of variable depth is introduced into a flat drop-stitch component (8) such that the outer skin of the drop-stitch component can be folded on one side of the drop-stitch component or, according to the position of the fold, alternately on both sides of the drop-stitch component.
The invention relates to a drop-stitch element according to the characterising clause of patent claim 1, and, to a method for producing a drop-stitch element according to patent claim 10.
In a drop-stitch material, thousands of equally long polyester threads hold together, in parallel, two oppositely disposed materials, also referred to as top and bottom. Owing to its design, this special drop-stitch material is produced in webs. The starting material is open on all sides when viewed perpendicular to the stretched polyester threads and needs to be provided with side walls in order to obtain a closed body. This closed body can be filled with air. These air-filled bodies, due to their structure, are completely flat and do not have any curved elements when viewed along the surface.
Inflatable watercraft, such as kayaks, canoes and surfboards, can be made from drop-stitch material. A typical kayak has a bottom which is adapted to the longitudinal axis of the boat, in such a way that it determines the shape of the boat. The two side walls are adhesively bonded to the outer sides of the bottom.
In the case of this adhesive method, the side walls bulge in a longitudinal direction, that is to say a direction of travel, in line with the shape of the bottom. In this case, the bow and stern are usually relatively tapered, for example tapered in such a manner that a hydrodynamically optimised bow structure can be formed, since a drop-stitch material does not permit tapering due to the nature of the material. The inclination of the side walls is attained by an additional, adhesively bonded outer skin, which, after inflation and the associated spacing between bottom and side wall, comes under tension and maintains the side wall at a stable predetermined angle, which is usually selected such that the boat is wider at the top and narrower at its bottom. The biggest problem of this type of construction is, on the one hand, the air-tightness of the boats and, on the other hand, the enormous manual work required for bringing about adhesive bonding with precision. In order to better illustrate this, the length of the adhesive bonds of a kayak measuring 5 metres in length is described:
A kayak of this type consists, inter alia, of two side walls, to each of which, at the end faces, an end strip is to be adhesively bonded, which corresponds to the drop-stitch thickness. This brings about four side strips with adhesive bonding on the left and on the right sides, adding up to an adhesive length of 20 m. A bottom, likewise having a length of five metres, which is to be adhesively bonded to an end strip on the left and the right sides, results in ten metres of adhesive length. In order to attain good air-tightness, all adhesive bonds have to be sealed off with an additional, second adhesive bond in the form of an adhesive tape which is applied over the first adhesive bond.
This means an adhesive length of a further 60 m, since the first adhesive bond is to be sealed off in each case on the left and right sides. Altogether, in the case of a kayak which is as airtight as possible, consisting of drop-stitch material, approximately 90 running metres of adhesive bonding must be provided, duly applied through manual work. The reason for manual work being that the constantly changing adhesive bonding, progressing in curves, precludes mechanical production.
The great drawback of the adhesive techniques used to date for drop-stitch materials for boats resides in the fact that, owing to the straight surfaces of the drop-stitch structures, only a limited design is possible with regard to the hull. Essentially, only a straight flat bottom is possible, having two straight flat and joined side walls, since the drop-stitch material with its holding threads between the walls naturally aims for straight flat shapes after inflation.
It is thus the object of the invention to provide a drop-stitch element with as few openings—and thus adhesive surfaces—as possible for enhanced air-tightness, permitting rounding of the flat drop-stitch component. A method for the production thereof is a further object of the invention.
These objects are attained by a drop-stitch element according to claim 1 or, respectively, a method for producing a drop-stich element according to claim 10. Advantageous further developments are set out in the subsidiary claims.
The drop-stitch element according to the invention is designed in such a way that at least one fold is introduced into a drop-stitch component. This fold is variable in its depth, that is to say, in the overlap of the parts lying opposite one another as a result of the fold. The overlapping regions of the drop-stitch component, that is to say, the regions of an outer skin which are either the top or the bottom of the drop-stitch material, are adhesively bonded to one another.
According to the invention, the depth of the fold changes according to the position and/or the position of the fold in the drop-stitch element. Irrespective of the depth of the fold, the latter is, however, oriented towards the inner region of the drop-stitch element, or, respectively, the drop-stitch component and is introduced either on one side and/or on both sides, i.e., for example, alternately, or also on other sides of the drop-stitch component.
In a preferred embodiment, the fold starts at the surface, i.e. at the top or bottom of a drop-stitch material of a drop-stitch component, thus having a minimum depth at this point, that is to say, a very small overlapping region of the outer skin. In the further progression of the fold, the depth changes, i.e. increases, so that the overlapping region expands. This continues up to a certain point in the drop-stitch component, at which, consequently, the greatest overlap is provided, running up to that point in a curved manner, a straight-line or linear configuration also being conceivable. As soon as a point is reached, at which the maximum depth of the fold is provided, the depth and thus also the overlap region decrease again in a further curving, straight or linear progression, in order to terminate again at the surface.
In a further embodiment, a plurality of folds are provided in a drop-stitch component, which are introduced lying alongside one another on one side, that is to say, on the top or bottom side of the drop-stitch material. These folds as well are each adhesively bonded to one another.
Wedge-shaped punched-out portions, that is to say, material removed from the drop-stitch material, starting from the top towards the bottom, or vice versa, in a configuration tapering from the outside to the inside, have proved to be particularly advantageous, when a rounded shape of the drop-stitch element, or of the drop-stitch component, also referred to as a drop-stitch body, is desired. The wedge-shaped punched-out portions, in combination with the fold or folds, urge the drop-stitch element into a rounded shape, thus permitting an even more variable design of the drop-stitch element.
For aesthetic, optical and/or haptic reasons, the folds may be covered by a flat blank. For this purpose, for example, a material similar to the top or bottom is adhesively bonded or otherwise fixed above the seam, which is created during the folding process. An even more even surface structure than is in any event achieved by the folds in comparison with a double-bonded structure, known from prior art, can thus be attained.
In a further embodiment, the folds are introduced into the drop-stitch component alternately, that is to say, on both sides. The resulting drop-stitch element thus has, for example, a double hull, since the fold is introduced into and adhesively bonded to the top and bottom of the drop-stitch component.
In order to attain an elongated hull shape of the drop-stitch element, two drop-stitch components, in each case having at least one fold, can be aligned in relation to each other in mirrored fashion, such that a solid element located between the two drop-stitch components, for example, an annular element, is encompassed by the two drop-stitch components and that the latter are kept in spaced apart relationship from one another in at least one, preferably an upper, central region while the lower region preferably forms a continuous flush border or transition between the two drop-stitch elements.
In order to form a pointed stern and a pointed bow, it is preferred if a rigid bow or stern element is fitted to the end faces of the drop-stitch components, at the point where they are at a short distance from one another, that is to say, in a transition region from the tapering upper region towards the lower region. This bow or stern element is encased by a waterproof envelope which is braced on inflation of the drop-stitch components, forming with the bow and stern elements a pointed bow and a pointed stern on the drop-stitch element.
It is particularly preferred if the rigid bow and stern elements are fixed resiliently to the end faces, that is to say, to the bow and/or the stern of the drop-stitch element, or to the drop-stitch components.
A method according to the invention for joining a drop-stitch element is characterised by an adhesive technique. This novel adhesive technique resides in the fact that, for example, a boat which has to date been composed of three independent bodies, namely two side walls and a bottom, is built, according to the invention, by using only one or two drop-stitch bodies. These drop-stitch bodies have fewer adhesive bonds, which improves the air-tightness and brings about a marked reduction in production costs.
A further advantage of the method according to the invention is that these adhesive bonds are freely accessible for any repair work in the event of a leak, whereas in the case of previously applied adhesive methods the defective adhesive bonding points are no longer accessible in the event of damage, since they are covered by an outer skin. With the adhesive technique according to the invention, one side of the drop-stitch body is folded inwards, which results in the buckling of the drop-stitch body. In addition, the inward fold is brought about in a curved progression, which results in a bulging shape of the drop-stitch body.
For a smooth production sequence, two mirror-image, i.e. mirror-symmetrical sides can be assembled to form one part. This design has the advantage that adhesive bonding of a plurality of folds can be performed more easily and more quickly in a left and right individual half.
Punching out on surfaces which require particular rounding, has proved to be very practical. A wedge of the drop-stitch material is removed, that is to say, punched out, and the sides are joined together again, the seam in the drop-stitch material being closed by a cover.
The adhesive bond may be designed with a plurality of adjacent folds which begin at the surface of the drop-stitch material and extend in curved progression to a maximum depth in order to then return again to the drop-stitch surface, which is required, for example, for a belly-shaped rowing boat.
Transport of a particularly long conventional watercraft, which is also known as a so-called surf ski, can become difficult, for which reason, in this case, an inflatable design is appropriate. These very long drop-stitch constructions can be kept dimensionally stable by middle segments. In a light-weight version, the middle segment consists of a robust outer woven cover with an inner, inflatable airtight envelope. However, the middle segment may also consist of only one inflatable plastic cover. A plurality of solid segments are also suitable as middle segments, encompassed by the two side walls.
For optical reasons, folds on the upper surface of boats can also be covered by a covering layer.
Further details are set out in the description of an embodiment, reference being made to the accompanying drawings.
There are shown in:
The tapered bow shape according to
The illustrations in
A lower fold 12b begins in the front third of the surface of the inner side 12c of the side wall 22 and widens in a rounded progression in the centre of the boat up to a maximum depth 12e. The effects of the depth of the fold have already been described in detail when describing
The invention relates to a drop-stitch element, in which at least one adhesively bonded fold of variable depth is introduced into a flat drop-stitch component such that the outer skin of the drop-stitch component can be folded on one side of the drop-stitch component or, according to the position of the fold, alternately on both sides of the drop-stitch component.
LIST OF REFERENCE NUMERALS
- 1 Left side wall
- 2 Right side wall
- 3 Bottom
- 4a, 4b, 4c End strips
- 4d Circumferential end strip
- 5 Sealing tape
- 6 Bottom layer
- 7 Inside adhesive bonding
- 8 Drop-stitch part
- 9 Left fold
- 10 Right fold
- 11 Upper edge
- 12a Upper fold
- 12b Lower fold
- 12d, 12d Surface inner wall
- 12e, 12f Maximum depth
- 13 Bow, tapering
- 14 Left half
- 15 Right half
- 15a Punched-out portion
- 15b Joined punched-out portion
- 15c Air-tight cover
- 16a Left end face
- 16b Right end face
- 17 Waterproof envelope
- 18 Rear end
- 19 Rigid bow and stern element
- 20 Fastening tube
- 21 Tabs
- 22 Side wall
- 23 Seat, removable
- 24 Middle segments, inflatable
- 25 Solid element
- 26 Bottom-side fold
- 27 Top-side fold
- 28 Round outline
- 29 Bridge
- 30 Inner side wall
- 31 Centre-fold
- 32 Keel
- 33 Covering layer
- A Length
- B Length
Claims
1. Drop-stitch element, characterised in that at least one fold (9, 10, 12a, 12b) of variable depth is adhesively bonded into a flat drop-stitch component (8), wherein the outer skin of the drop-stitch component is folded or folded inwards on one or alternately on both sides of the component (8).
2. Drop-stitch element according to patent claim 1, wherein the fold (9, 10, 12a, 12b) starts at the upper surface of the drop-stitch component (8) and then extends increasingly deeper, in curved progression, to a maximum depth (12e, 12f), in order to then terminate, once again in curved progression, at the upper surface.
3. Drop-stitch element according to patent claim 2, wherein a plurality of adjacent folds (9, 10, 12a, 12b) are adhesively bonded into one side of the drop-stitch material.
4. Drop-stitch element according to any one of the preceding patent claims, wherein wedge-shaped punched-out portions (15a) are provided, in addition to the folds (9, 10, 12a, 12b), in order to urge the drop-stitch body into a rounded shape.
5. Drop-stitch element according to any one of the preceding patent claims, wherein the fold (9, 10, 12a, 12b) is covered by a covering layer (33) and/or a punched-out portion (15a) is covered by a cover (15c).
6. Drop-stitch element according to any one of the preceding patent claims, wherein a double-hull is produced by alternate folding (26, 27).
7. Drop-stitch element according to any one of the preceding patent claims, wherein by means of a drop-stitch component (8), having at least one fold (12b), and a second drop-stitch component (8), mirrored with respect to the first, an elongated hull shape is brought about in that the mirrored drop-stitch component (8) stretches around an inflatable or solid element (25).
8. Drop-stitch element according to patent claim 7, wherein a rigid bow and stern element (19) is fitted to the end face (16a, 16b) of the two drop-stitch bodies (8) at the bow and the stern, which bow and stern element is braced in a waterproof envelope (17) after inflation and forms a preferably pointed bow (13) and/or a preferably pointed stern.
9. Drop-stitch element according to patent claim 8, wherein the rigid bow and stern element (19) in the waterproof envelope (17) is attached, preferably spring-mounted, to the end face (16a, 16b) of the drop-stitch body at the bow and stern.
10. Method for joining a drop-stitch element according to any one of the preceding claims, characterised by an adhesive technique, wherein one side of at least one drop-stitch component (8) is folded and adhesively bonded in the region of the fold (9, 10, 12a, 12b).
11. Method according to claim 10, characterised in that two mirror-identical drop-stitch components (8) are combined to form a drop-stitch element.
Type: Application
Filed: Jul 2, 2019
Publication Date: Nov 18, 2021
Inventor: Ernstfried Prade (Kinsau)
Application Number: 17/287,426