U.S. patent application number 10/491062 was filed with the patent office on 2005-02-24 for method for the production of a flexible bulk-material container and bulk-material container produced according to said method.
Invention is credited to Glotzbach, U., Hartmann, Siegfried, Wolff, E.K., Wurr, Egon.
Application Number | 20050041893 10/491062 |
Document ID | / |
Family ID | 26076729 |
Filed Date | 2005-02-24 |
United States Patent
Application |
20050041893 |
Kind Code |
A1 |
Hartmann, Siegfried ; et
al. |
February 24, 2005 |
Method for the production of a flexible bulk-material container and
bulk-material container produced according to said method
Abstract
The invention relates to a flexible bulk-material container made
of at least one woven blank of a synthetic strip-type material and
to a method for the production thereof. In the seam areas (25),the
woven blank (20.1) is provided with an overlapping or another woven
blank (20.2) placed on top. An energy conversion agent 924) is
inserted into the boundary layer (22) which is disposed between the
overlapping and/or woven blanks placed on top (20.1, 20.2). The
woven blank or blanks (20.1, 20.2) is/are melted by means of laser
beams acting upon the energy conversion agent (24).
Inventors: |
Hartmann, Siegfried;
(Ibbenbueren, DE) ; Wurr, Egon; (Rheine, DE)
; Wolff, E.K.; (Herdecke, DE) ; Glotzbach, U.;
(Witten, DE) |
Correspondence
Address: |
Karl F Milde Jr
Milde & Hoffberg
Suite 460
10 Bank Street
White Plains
NY
10606
US
|
Family ID: |
26076729 |
Appl. No.: |
10/491062 |
Filed: |
October 18, 2004 |
PCT Filed: |
September 28, 2002 |
PCT NO: |
PCT/EP02/10923 |
Current U.S.
Class: |
383/107 ;
383/117; 383/121 |
Current CPC
Class: |
B29C 66/71 20130101;
B29K 2307/00 20130101; B29C 66/71 20130101; B29C 66/45 20130101;
B29C 66/71 20130101; B29L 2031/7126 20130101; B29K 2995/0027
20130101; B29C 66/112 20130101; B29K 2023/06 20130101; B29K
2067/003 20130101; B29C 66/232 20130101; B29C 66/729 20130101; B29C
66/71 20130101; B29K 2023/065 20130101; B29K 2023/12 20130101; B23K
26/244 20151001; B29C 2035/0827 20130101; B29C 65/1674 20130101;
B65D 88/1681 20130101; B29C 66/135 20130101; B29C 66/71 20130101;
B29C 65/1664 20130101; B29L 2009/00 20130101; B29C 66/4322
20130101; B29C 65/168 20130101; B29C 66/1122 20130101; B29C 66/4326
20130101; B29C 66/836 20130101; B29C 35/0805 20130101; B29C
66/73921 20130101; B29C 65/1635 20130101; B29C 66/43 20130101; B29C
2035/0822 20130101; B29C 66/7292 20130101; B29C 65/1654 20130101;
B65D 88/1612 20130101 |
Class at
Publication: |
383/107 ;
383/117; 383/121 |
International
Class: |
B65D 030/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 29, 2001 |
EP |
01123507.4 |
Oct 1, 2001 |
EP |
01123553.8 |
Claims
What is claimed is:
1. Method for producing a flexible bulk-goods container from a
plastic strip fabric comprising the following steps: a) introducing
of the energy of a laser beam with an energy-conversion medium that
absorbs wavelength .lambda..sub.1 and converts it into thermal
energy into a seam area of at least one cut-fabric section, the cut
fabric section comprising a plastic that is light permeable to the
laser beam; b) producing an overlap of the cut-fabric section in a
seam area thereby forming a boundary layer between the overlapping
fabric layers; c) penetrating at least one of the fabric layers
with a laser beam having a wavelength of .lambda..sub.1 in the seam
area; d) allowing partial melting of the fabric layers in their
surface area under formation of a weld seam location as a
homogeneous bond between the fabric layers (20.1, 20.2); and e)
repeating steps b) through d) until all seam areas are welded.
2. Method as defined in claim 1, wherein the energy-conversion
medium is impressed onto at least one of the fabric layers.
3. Method as defined in claim 2, wherein the energy-conversion
medium is impressed onto the seam area.
4. Method as defined in claim 2, wherein the energy-conversion
medium is impressed onto the entire area.
5. Method as defined in claim 1, wherein the energy-conversion
medium is inserted between the fabric layers in the form of a
light-energy-absorbing welding film.
6. Method as defined in claim 1, wherein the energy-conversion
medium is mixed into the plastic of at least one of the fabric
layers.
7. Method as defined in claim 1, wherein a first cut-fabric section
is welded into a cylinder that is welded to a second cut-fabric
section as a floor section.
8. Method as defined in claim 1, wherein a first cut-fabric section
is welded into a cylinder, and wherein a floor section is formed by
multiple folding and repositioning of partial areas of the
cut-fabric section, whereby the folds are fixed by laser beam
welding.
9. Method as defined in claim 8, wherein a floor and/or roof area
is formed using the following process steps: a) folding the
cylindrical cut fabric section flat into a two-layer flat piece; b)
producing a first fold mark on both fabric layers over the entire
width of the flat piece at a distance to the lower edge
corresponding to half the width of the flat piece; c) producing a
second and third fold mark starting from the center of the lower
edge to each cutting point of the first fold mark with a side edge
of the flat piece; d) inserting a first and second side-edge
section that extends between the lower edge and the first fold mark
into the interior of the two-layer flat piece by folding the fabric
along the second and third fold marks up to the overlay of the
side-edge sections on the first fold mark in the interior of the
two-layer fabric; e) folding the triangular sections thus formed
and overlaying the corners into the area of the first fold mark;
and f) affixing the triangular sections and/or by penetrating
laser-beam welding of the seam areas.
10. Method as defined in claim 1, wherein at least one cut fabric
section is formed by corner extraction of two asymmetrical,
mirror-reflected along one edge trapezoidal sections, whereby the
cut fabric section thus obtained includes at least: a rectangular
sidewall area; a trapezoid-shaped floor or roof area adjacent to
the sidewall area; and a rectangular reinforcement area adjacent to
each floor and/or roof area whose sidewall, floor, roof, and/or
reinforcement areas each are welded in edge seam areas.
11. A flexible bulk goods container comprising at least one cut
fabric section made of plastic fabric band, wherein the cut fabric
section overlaps in the seam areas or is provided with an
additional cut fabric section laid on it, and wherein an
energy-conversion medium is inserted into the border layer, and the
cut fabric sections is/are melted by laser beams acting on the
energy-conversion medium(s).
12. A flexible bulk goods container as defined in claim 12, further
comprising a surrounding sidewall and at least one floor section
and/or roof section wherein the sidewall and floor section and/or
roof section is/are formed of the same cut fabric section, and
wherein the seam areas of the cut fabric section are formed in the
seam areas overlapping with the energy-conversion medium inserted
into the intermediary border layer, and is melted by the laser
beams (11, 11') acting on the energy conversion medium.
13. A flexible bulk goods container as defined in claim 12, wherein
the floor section and/or roof section includes a round recess that
is formed by means of quarter-circle shaped recesses near at least
two corners of the cut fabric section that has been folded into a
flat piece, and by at least one half-circle recess positioned in
the center of an open edge of the flat piece.
14. A flexible bulk goods container as defined in claim 12, further
comprising at least one surrounding sidewall and at least one floor
or roof section, and by four cut fabric sections that are welded at
seam areas near the edges, wherein each cut fabric section includes
at least: a rectangular sidewall area; a trapezoid-shaped floor or
roof area adjacent to the sidewall area; and a rectangular
reinforcement area adjacent to each floor and/or roof area.
15. A flexible bulk goods container as defined in claim 10, wherein
at least one carrying handle is positioned on the sidewall that is
connected to it by means of a separate finger-shaped welding
flap.
16. A flexible bulk goods container as defined in claim 10, wherein
the cut fabric section is at least partially provided with
micro-perforations that are spot-melted by laser beams.
17. Method as defined in claim 1, wherein the cut-fabric section
comprises a stretched tubular fabric, and wherein a floor section
is formed by multiple folding and repositioning of partial areas of
the cut-fabric section, whereby the folds are fixed by laser beam
welding.
Description
[0001] The invention relates to a method produce a flexible
bulk-goods container.
[0002] Also, the invention relates to flexible bulk-goods
containers that are internationally designated as Flexible
Intermediate Bulk Containers (FIBC) of a plastic strip fabric that
includes at least a surrounding sidewall and at least one floor
section or roof section.
[0003] DE 39 38 414 A1 shows a bulk-goods container that is
conventionally made of several cutouts to form a
quadrilateral-based container that, in filled condition, may
approach the cylindrical because of internal pressure by the bulk
material. Four side parts are provided that are seam-stitched
together along side edges. The sidewalls are seam-stitched with a
floor section that may also be provided with emptying aids such as
supports or similar. An additional roof section may be provided at
the top of the container so formed that it may be provided with
filling aids. Additionally, hoisting loops are attached to the
upper edges of the container in order to facilitate use with
hoists.
[0004] Production of a bulk-goods container by bonding individual
sections includes several disadvantages. Thus, needle penetration
weakens the material, which is usually a plastic fabric composed of
strips of polypropylene, polyethylene, or HD-polyethylene film so
that a perforation line occurs in the area of the stitches along
which stitch holes may be stretched when the container is filled
with a full load. Because of these perforations, the bulk-goods
container must be provided with an inner lining or seam covering
when fine bulk materials are to be transported, or when the
bulk-goods container is to be suitable for foodstuffs, so that a
hermetic seal of the bulk material is protected against
environmental influences.
[0005] In order to prevent spreading of the stitch holes, a thick
flat piece must be used that is over-dimensioned with respect to
the theoretical forces acting on the unweakened fabric. Additional
reinforcement layers must be stitched into the stitched-seam
area.
[0006] Also, production according to the state of the art requires
numerous production steps from cutting to size and pre-decoration
of the individual parts, the subsequent stitching, and to the final
visual inspection. Production must largely be manual.
[0007] In order to weaken the strong forces on the side stitched
seams, it is known to stitch edge reinforcements along the entire
height of the container in order to prevent the bulk goods from
flowing into the lateral stitched-seam areas, thus producing large
forces directly on the side stitched seams. According to the state
of the art, such edge reinforcements may only be stitched up to a
certain height of the container since the stitch length to be
bridged is more than one meter itself, and industrial sewing
machines do not allow stitching of such a seam.
[0008] U.S. Pat. No. 5,845,995 describes a packaging sack formed by
folding a polyolefin tubular fabric. Next a molten intermediate
layer of a thermoplastic polymer is inserted in the area of the
folded layers to which the folded layers adhere, resulting in a
tightly-sealed floor area. The injection of the intermediate layer
is difficult, however. There is also the disadvantage that the
fabric is partially melted by the heat transfer, the infiltrating
molten mass from the intermediate layer, and the full-surface
adhesion, thus losing its flexibility. The so-called "memory
effect" occurs to a fabric of stretched plastic strips as a result
of the heat influence, i.e., the stretching causes a breakdown
whereby the strength of the fabric is reduced.
[0009] It is thus the principal objective of the invention to
provide a manufacturing method for a flexible bulk-goods container
that allows significantly simpler and lower-cost manufacturing than
does the state of the art. Also, its load-bearing capacity should
increase, or the use of fabrics with lower weight per surface area
would be allowed.
[0010] This objective is achieved in accordance with the invention
by a method to manufacture a flexible bulk-goods container that
possesses the following steps:
[0011] a) inserting of an energy-conversion medium that absorbs the
light energy from a laser beam with wavelength .lambda. and
converts it into thermal energy at a seam area of at least one of
the fabric sections, whereby the fabric section comprises a plastic
that is light permeable to the laser;
[0012] b) producing an overlap of the fabric section at a seam area
thereby forming a boundary layer between the overlapping fabric
layers;
[0013] c) penetrating at least one of the fabric layers with a
laser beam having a wavelength .lambda. at a seam area;
[0014] d) allowing partial melting of the fabric layers in the
surface area at the boundary layer, and allowing them to cool under
formation of a weld seam location as a homogeneous bond between the
fabric layers; and
[0015] e) repeating steps b) through d) until all seam areas are
bonded.
[0016] The laser beam passes through the polypropylene fabric of
the outer layer, penetrates in the area of the boundary surface
between the adjacent fabric layers, and strikes energy-conversion
medium embedded in the boundary layer. Here, the emitted light
energy is converted into thermal energy that leads to local warming
and partial melting of the fabric. The partial melting of both
matching pieces in the area of the boundary layer leads to melting,
and thus to a fused bond. It is even possible to pass the laser
beam through several layers of fabric to an inner boundary layer
not light permeable to create a weld seam for which an
energy-conversion medium is provided at this boundary layer at
least in the area of the seam. The method according to the
invention may be automated, and thus may be performed at low cost.
It is also possible using penetrating-laser welding to position
weld seams anywhere functionally useful. Seams may also be created
at locations not accessible to a sewing machine. It is thus
possible to re-conceive a bulk-goods container, and sharply to
reduce the number of parts required for its production.
[0017] It is also advantageous for the strength of the stretched
plastic strips most often used for the manufacture of flexible
bulk-goods containers to remain high, since, in contrast to welding
by a heated element, the fabric is not completely warmed and
reduction in stretch capability is not reduced.
[0018] Since, in contrast to a process using a needle, no weakening
of the fabric because of perforation ensues, a fabric may be
selected that possesses a lower weight per surface area than is
required for stitched containers.
[0019] It is further advantageous for the position of the stitches
to be simply matched to the forces within the fabric, and
complicated shapes of the cut sections may be undertaken without
significant increase in production costs.
[0020] Further, it is possible to bond rigid and flexible fabrics
together. This is possible with all combinations of thermoplastic
materials in which mixture of the molten mass is possible. If, for
example, a polypropylene-strip fabric is used, then
injection-molded polypropylene parts may be bonded to the fabric
without difficulty. This allows welding of supporting tubes in the
floor or ceiling area that considerably simplify docking to a
filling or emptying station. Also, additional parts may be welded
on that allow automated gripping of the filling or emptying
fittings of the bulk-goods container, e.g., those formed in the
shape of a bayonet fitting.
[0021] Use of corner reinforcement is also possible without
difficulty using penetrating-laser welding since merely the laser
head need be led along the inner wall of the container in order to
attach the corner reinforcement to the sidewall. Limitation to seal
length as with sewing machines does not occur here.
[0022] It may be provided that the fabric be coated with an
energy-conversion medium that absorbs the light energy of a laser
at a specific wavelength, or to mix the plastic with an
energy-conversion medium before fabric production.
[0023] It is preferred that the prepared fabric section is provided
with an energy-conversion medium only in the region of the
subsequent weld seams, e.g., by pressing.
[0024] The energy-conversion medium may further be prepared in the
form of a welding film that is inserted into the boundary layer in
the area of the desired seams. The welding film consists of a
carrier plastic mixed with light-absorbing pigment. The thickness
of the welding film whose melting temperature or degree of
absorption of the pigment is so selected that either the welding
film melts completely in the region of the weld seam creating a
molten mass of plastic that causes local partial melting of the
fabric to be welded, or that the welding film is merely heated and
both fabric layers adhere to each other or are intensively bonded
by means of the intermediary welding film.
[0025] It is possible to weld a first cut fabric section into a
cylinder that is subsequently welded to a second cut fabric section
as a floor, and to cut other fabric sections such as ceiling
sections and filling and emptying aids.
[0026] Using the method according to the invention, one preferably
starts with a stretched fabric tube so that the cutting is further
simplified. The cut fabric section is then folded several times,
and is welded in the area of the overlap of the folds by the
effects of a laser beam.
[0027] It is also recommended to perform a micro-perforation by
pulsed laser energy. Micro-perforations may be simply created at
least in regions of lower loading using a sharply focused laser
beam that contributed to controlled ventilation of the interior of
the container without allowing escape of the bulk material.
[0028] One may dispense with the previously required mounting of
reinforcement areas in the area of the hoisting loops. It is
recommended for heavily loaded containers here to compartmentalize
the flap area welded to the container and to weld on the individual
fingers of the compartments to the container in order to achieve a
higher degree of force distribution. The larger number and length
of the weld seams no longer presents a disadvantage to an automated
process based on the invention.
[0029] Mounting of conventional welding surfaces with almost
perpendicular cut sections is also possible.
[0030] In the following, the invention is described in further
detail by embodiment examples and with reference to the
illustrations, which show:
[0031] FIGS. 1a, 1b are schematic views of welding a cut-fabric
section into a cylinder;
[0032] FIGS. 2a, 2b are schematic cutaway views of welding two or
three fabric layers by means of laser penetration welding;
[0033] FIGS. 3a-3c show preparation of a section of fabric tubing
by means of folding and positioning at various stages of the
procedure;
[0034] FIGS. 5a, 5b show an additional section of fabric tubing
before preparation for the manufacture of a bulk-goods container by
folding and positioning;
[0035] FIG. 6 is an additional section of fabric tubing before
decoration for the manufacture of a bulk-goods container by edge
welding;
[0036] FIG. 7 is a schematic cutaway view of welding of an overlap
area; and
[0037] FIG. 8 is a perspective view of another embodiment form of a
bulk-goods container.
[0038] FIG. 1a shows a cut-fabric section 20 onto which an
energy-conversion medium is pressed or otherwise mounted. The
energy-conversion medium may consist of carbon, particularly in the
form of soot. Since carbon absorbs light of all wavelengths,
various lasers may be used, particularly low-cost semi-conductor
lasers.
[0039] In FIG. 1b, the cut-fabric section 20 is rolled into a
cylinder by means of formation of an overlap at the seam area 25.
The laser beam 11 from a laser 10 is deflected using an optical
device 14 and is projected along the seam area 25.
[0040] Welding of the cut-fabric sections using laser penetration
welding is explained with reference to FIG. 2. There, two adjacent
fabric layers 20.1, 20.2 are shown in whose boundary layer 22 an
energy-conversion medium 24 is partially embedded. The
artist-rendered dimensional relationships in FIG. 2 are not to
scale, and serve merely for elucidation.
[0041] The energy-converting medium 24 is usually applied with a
thickness of about 1-100 .mu.m so that the boundary layer 22 also
possesses the same thickness. The thickness of the upper fabric
layer 20.1 to be penetrated may possess any light permeability for
the laser beam 11 as long as the light damping within the fabric
layer 20.1 is not so strong that partial melting of the boundary
layer 22 is no longer achievable. The thickness of the
non-penetrated lower plastic part 20.2 is not significant.
[0042] The laser beam penetrates the plastic part 20.1, strikes the
energy-conversion medium 24 embedded in the boundary layer 22,
whereby the light energy is converted into thermal energy. Based on
the laws of thermodynamics, and with respect to environmental
influences, e.g., by cooling, the amount of heat per time may be
calculated that must be input to the boundary layer in order to
cause partial melting of the fabric layers 20.1, 20.2 but without
causing complete melting, softening, or destruction of the fabric
layers 20.1, 20,2.
[0043] For all welding process based on the invention, a
lens-shaped weld seam location 23 is formed by the welding step
that becomes molten and then cools and hardens after termination of
the irradiation. The plane of symmetry of the weld seam location 23
lies approximately within the boundary layer 22, whereby even force
progression and a high degree of load-bearing capacity is
achieved.
[0044] Based on the method presented by the invention, the
following option shown schematically in FIG. 2b is presented:
[0045] An additional laser 10' with a wavelength .lambda..sub.2 can
be provided. An energy-conversion medium 24' additional to the one
in the existing seam area 25 is inserted into the boundary layer
22, or with more than two fabric layers 20.1, 20.2, 20.3, into an
additional boundary layer 22' that absorbs light at wavelength
.lambda..sub.2, but not to the extent that partial melting is
caused. Thus, an additional seam area 25' is formed. It is thus
possible to create two or more adjacent seams simultaneously by
means of laser penetration welding.
[0046] It is further possible to use an energy-conversion medium
that absorbs only a component of the energy at each of the
wavelengths .lambda..sub.1 and .lambda..sub.2. Upon irradiation by
a only one of the laser beams 10 or 10', only local warming occurs,
but not partial melting and welding. Only when several laser beams
11, 11' with wavelengths .lambda..sub.1 and .lambda..sub.2 are used
is the energy contribution sufficient to create a weld seam
location 23, 23'. It is thus possible to weld only the cross-points
in a fabric if the weft yarn is coated with a first
energy-converting medium 24, and the woof yarn with a second
energy-conversion medium 24'. In the overlap at the node points,
both energy-converting media 24, 24' are adjacent, so that a laser
beam with wavelength .lambda..sub.2 can only cause a weld at those
positions while it otherwise may shine over the surface of the
fabric without causing partial melting. The fabric remains flexible
because of the connections only at the node points.
[0047] A flexible fabric is also obtained if an individual laser is
coupled with an image-processing system and a control device
through which switching the laser beam on only occurs at the node
points of the weft and woof threads. In such case, it is adequate
to apply an energy-conversion medium to the woof or weft
threads.
[0048] FIGS. 3a through 3c show the preparation of a section of
fabric tube for the manufacture of a bulk-goods container. Either a
tubular fabric is selected or, as shown above under FIGS. 1a, 1b, a
flat cut-fabric section 20 is formed into a tube.
[0049] A polypropylene strip fabric is preferably selected where
the strip width is preferably 1 to 4 mm, and preferably stretched
to a ratio of 1:7 or 1:6. Fabric tension strengths of about 250
N/mm.sup.2 have been achieved particularly by the use of mono-axial
stretching. The polypropylene strips may be composed as follows,
for example:
[0050] 95% polypropylene
[0051] 1.5% UV stabilizer
[0052] 3.5% anti-split medium, e.g., calcium carbonate, titanium
oxide, talc, etc.
[0053] In addition, fabrics of polyethylene, HDPE, and PET may be
processed by the invention.
[0054] The cut-fabric section 20 is provided with an impression of
an energy-conversion medium 24 that corresponds to the subsequent
seam.
[0055] As FIG. 3a shows, the tube section is flattened to a flat
piece 30. Subsequently, several fold marks 41, 43, 44 are mounted
and corners are reinforced until a folded floor or roof section of
the bulk-goods container is formed.
[0056] The folding of a floor and/or roof section results from
further procedure steps (see FIG. 3a).
[0057] Then, a first fold marking 41 is produced on both fabric
layers along the entire width of the flat piece 30, namely at a
distance from the lower edge 31 corresponding to the half-width of
the flat piece 30.
[0058] A second and a third fold marking 43, 44 are produced
starting from the middle of the lower edge 31 to the intersection
point with the first fold marking 41 with a side edge 32, 33 of the
flat piece 30.
[0059] A first and a second side edge section 32.1, 33.1 that
extends between the lower edge 31 and the first fold marking 41 are
pushed into the interior of the two-layered flat piece 30. Thus,
the fabric is bent along the second and third fold markings 43, 44.
In the final position of this production step, the side edge
sections 32.1, 33.1 lie within the interior of the two-layered flat
piece 30 at the first fold marking 41.
[0060] A configuration shown in FIG. 3b arises that possesses a
clearly visible triangular area 45, 46. These are approximately
bent in half so that their corners 46, 47 rest in the area of the
first fold marking 41, and the final condition shown in FIG. 3c is
achieved.
[0061] Only very low tensile forces act on the free corners 46, 47
of the bulk-goods container so formed, so that a very short weld
seam is adequate to bind the corners 46, 47 to the fabric 20. For
example, the corners may be connected using an arc-shaped weld seam
area 25.
[0062] The illustrated simple production of a bulk-goods container
100 by folding and repositioning is essentially based on the laser
welding method used here, because it would not be possible with
conventional stitching equipment to stitch seam sections 25 with a
sewing machine in the area of the floor or ceiling sections.
[0063] FIG. 4 shows a completed bulk-goods container 100 provided
with hoisting loops 60. The welded flaps 61 of the hoisting loops
60 are also divided into compartments; the individual compartments
are welded to the sidewalls in such manner that they are positioned
approximately along the anticipated force directions. Laser beam
welding using an energy-conversion medium pressed in place allows
the provision of numerous complex weld steps, even with the
compartmentalized weld flaps. No production cost increase results
since the pressing of the energy-conversion medium for all seam
areas may be performed in one step, and the welding may be
automated using laser beams and electronic assembly-line
control.
[0064] Welding of conventional hoisting loops with approximately
rectangular weld flaps is also possible based on the invention.
Such weld flaps are adequate under normal loading. Here also, rapid
production of seams may be achieved via the invention.
[0065] FIG. 5a shows another flat piece 30 that includes
quarter-circle arc cutouts at the edges of the lower edge 31. Also,
an additional semi-circular cutout shape defined by the impression
of the energy-conversion medium 24 is present. By use of the
procedure steps explained previously with reference to FIGS. 3a
through 3c, a bulk-goods container is produced with which the
quarter- or semi-circular arc-shaped cutouts 26, 27 on the floor or
ceiling section are expanded to a circular cutout 28 shown in FIG.
5b to which filling or emptying fittings may be mounted.
[0066] Another production method of a bulk-goods container with,
for example, impressed energy-conversion medium, is first made
possible using application of laser-beam welding based on the
invention that is described with reference to FIG. 6 through 8 as
follows:
[0067] At least one cut-fabric section 40 (see FIG. 6) is formed by
corner cutouts of two symmetrical, mirror-reflected trapezoidal
sections 44 opposing an edge. The cut fabric piece 40 thus
produced,includes at least:
[0068] a right-angled sidewall area 42;
[0069] a trapezoid-shaped floor or ceiling area 43, 45 connected to
the sidewall area 42, and
[0070] a right-angled support area 41 adjacent and connected to the
floor and/or ceiling area 43, 45.
[0071] Either a tubular fabric may be correspondingly be processed,
or four identical cut-fabric sections 44 are combined. If a tubular
fabric is provided with cutouts 44, an endless tubular body is
formed in the sidewall area. In both cases, the preferred
embodiment per FIG. 7, a cut-fabric section 40 is folded over in
the seam area 25. The short overlaid end is welded since the boring
effect on the weld seams is minimized. Using the method based on
the invention, the weld seam at the covered folded-over seam area
may be produced by irradiation from a laser 10. The laser beam 11
passes through the outer fabric layers until it strikes the
energy-conversion medium 24, thus causing melting of the
overlapping cut-fabric sections 40 there.
[0072] FIG. 8 shows a bulk-goods container 100' formed out of four
cut-fabric sections 40. The sidewall areas 42 are connected
together in the edge-side seam areas 25 shown in the Figure with a
dashed line so that an approximately quadrilateral, flexible
container is formed that is limited at the bottom by the connected
trapezoid-shaped floor areas 43, and at the top by the connected
trapezoid-shaped ceiling areas 45. A filling or emptying fitting is
connected in the center of each floor or ceiling. Based on the
invention, this bulk-goods container 100' is formed by seams
created by only four automated passes with the laser, while a
similar, conventional bulk-goods container assembled using manual
stitching required 20 cut sections and 36 individual seams.
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