Weaving loom and method for weaving multi-layer fabrics

Abstract

The present invention relates to a weaving loom and a method for weaving multi-layer fabrics. The weaving loom includes a weft insertion device (90) and main heddles moved by a jacquard-type main shed mechanism. The main heddles are used to guide main warp yarns (12) and define a main lease width (W11). According to the present invention, the weaving loom includes auxiliary heddles (21) moved by an auxiliary shed mechanism. The auxiliary heddles are used to guide auxiliary warp yarns (22) and define a clamping area (W21) arranged within the main lease width (W11). During the first weft insertion, the auxiliary heddles are configured to close the auxiliary shed of the auxiliary warp yarns to clamp the inserted weft yarn (100) while the main shed is still open.

Description

Technical Field

[0001] The present invention relates to a knitting loom for knitting multi-layer fabrics and a method for knitting multi-layer fabrics. Background Art

[0002] It is known to knit warp and weft yarns according to a multi-layer pattern to form a three-dimensional preform. Such preforms can be used to manufacture three-dimensional composite components, such as fan blades and the like.

[0003] EP3121317A1 discloses a method for knitting a fabric, in which, during the pulling of the weft yarn into the shed of the warp yarns, a predetermined group of warp yarns is moved to a semi-closed position for closing the shed around the inserted weft yarn. Thus, the inserted weft yarn is guided or clamped by this group of yarns during its translational movement, so that the weft yarn can be correctly and precisely positioned even if it is cut into a length relatively short compared to the total width of the fabric.

[0004] However, implementing this method requires the use of advanced looms, which include a plurality of individual actuators for driving the heddles along the width of the lease rods. This type of loom is complex and expensive. Additionally, although the only function of this group of yarns is to facilitate knitting by guiding or clamping the weft yarn, this group of yarns is still interwoven in the finished fabric. Therefore, it is difficult to select a yarn that is suitable for remaining in the finished fabric and correctly guiding or clamping the weft yarn without breaking.

[0005] DE102015109785 discloses a two-dimensional fabric used in the production of three-dimensional composite components. The fabric includes shortened reinforcing yarns bonded by bonding yarns. However, the reinforcing yarns are not fixed during knitting, so that an unsatisfactory positioning of the reinforcing yarns may occur. Summary of the Invention

[0006] An object of the present invention is to solve the above problems and provide a new knitting loom that can clamp the weft yarn during knitting and at the same time has a simpler structure.

[0007] The present invention relates to a weaving loom for weaving a multi-layer fabric including warp threads and weft threads, the weft threads having different lengths, wherein the weaving loom includes: an insertion device configured to: pick up a weft thread along the weft axis of the weaving loom at a weft insertion position; pull the weft thread from the weft insertion position along the weft axis into the shed of the warp threads; and release the weft thread at a given position along the weft axis. The weaving loom includes a main heddle configured to guide the main warp threads and define a main harness width along the weft axis. The weaving loom includes a main shed mechanism of the jacquard type configured to move the main heddle along a vertical path. The weaving loom includes a set of first auxiliary heddles configured to guide first auxiliary warp threads and define a first clamping zone along the weft axis, the first clamping zone being arranged within the main harness width. The weaving loom includes a first auxiliary shed mechanism configured to move the first auxiliary heddles. The weaving loom is configured to, at a first weft insertion: open the main shed of the main warp threads by the main heddle moved by the main shed mechanism, and open the first auxiliary shed of the first auxiliary warp threads by the first auxiliary heddles moved by the first auxiliary shed mechanism, so as to insert a first weft thread through the insertion device; and is configured to, at the first weft insertion: close the first auxiliary shed by the first auxiliary heddles moved by the first auxiliary shed mechanism, so as to clamp the first weft thread in the first clamping zone by the first auxiliary warp threads after the insertion device pulls the first weft thread through the first clamping zone and the main shed is still open.

[0008] The weaving loom of the present invention is implemented with a first auxiliary shed mechanism that is dedicated to positioning the first auxiliary warp threads by the first auxiliary heddles and is implemented as a structure independent of the main shed mechanism. Therefore, the first auxiliary shed mechanism and the first auxiliary heddles can be dedicated to clamping the weft thread at any weft insertion. The first auxiliary shed mechanism can be specifically designed for this purpose, while the main shed mechanism can still be general-purpose. Advantageously, the main shed mechanism can be implemented as including a mechanism with selectable hooks and blades for driving the main heddles, which has a lower cost than a mechanism that implies including multiple individual heddle actuators. However, the first auxiliary shed mechanism can be more specifically tailored to the weft thread clamping requirements, for example by including multiple individual actuators for driving the first auxiliary heddles.

[0009] In another embodiment, by adding an auxiliary shed mechanism and the first auxiliary heddles, an existing weaving loom that could not initially achieve weft thread clamping can be upgraded to a weaving loom according to the present invention to be able to achieve weft thread clamping.

[0010] Other alternative features of the present invention are given below.

[0011] Preferably, the first auxiliary shed mechanism is configured to close the first auxiliary shed to clamp the first weft thread when the insertion device is still pulling the first weft thread into the main shed.

[0012] Preferably, the weaving loom includes a set of second auxiliary heddles configured to guide second auxiliary warp threads and define a second clamping zone along the weft axis, the second clamping zone being arranged within the width of the main harness cords; and the weaving loom includes a second auxiliary shed mechanism configured to move the second auxiliary heddles. Preferably, the first clamping zone is arranged between the weft insertion position and the second clamping zone. Preferably, the weaving loom is configured such that during the first weft insertion: the second auxiliary shed of the second auxiliary warp threads is opened by the second auxiliary heddles moved by the second auxiliary shed mechanism to insert the first weft yarn through an insertion device; and the weaving loom is configured such that during the first weft insertion: the second auxiliary shed is closed by the second auxiliary heddles moved by the second auxiliary shed mechanism to clamp the first weft yarn in the second clamping zone by means of the second auxiliary warp threads after the insertion device has drawn the first weft yarn through the second clamping zone and while the main shed remains open.

[0013] Preferably, the first auxiliary shed mechanism is configured to close the first auxiliary shed to clamp the first weft yarn when the insertion device draws the first weft yarn into the second clamping zone.

[0014] Preferably, the weaving loom includes a beam supporting the first auxiliary shed mechanism, the position of the first auxiliary shed mechanism being adjustable along the beam in a direction parallel to the weft axis.

[0015] Preferably, the first auxiliary shed mechanism includes a main actuator for moving a main auxiliary heddle in the first auxiliary heddles according to a main reciprocating motion; and a secondary actuator for moving a secondary auxiliary heddle in the first auxiliary heddles according to a secondary reciprocating motion opposite to the main reciprocating motion to have an adjustable crossover point.

[0016] Preferably, the first auxiliary shed mechanism includes at least one actuator, the actuator including a stator and a pulley rotatably driven relative to the stator; and each pulley is configured to move at least one of the first auxiliary heddles, preferably three first auxiliary heddles.

[0017] Preferably, the main shed mechanism includes: selectable hooks, each selectable hook driving at least one of the main heddles; blades for driving the selectable hooks between an upward position and a downward position; and a main shaft for driving the blades.

[0018] The present invention also relates to a method of weaving a multi-layer fabric including warp and weft yarns by a weaving loom, the weft yarns having different lengths, the weaving loom including: an insertion device configured to: pick up a weft yarn at a weft insertion position along the weft axis of the weaving loom, pull the weft yarn from the weft insertion position along the weft axis into the shed of the warp yarns, and release the weft yarn at a given position along the weft axis. The weaving loom includes a main heddle configured to guide main warp yarns and define a main harness width along the weft axis. The weaving loom includes a main shed mechanism of the jacquard type configured to vertically move the main heddle along a vertical path. The weaving loom includes a set of first auxiliary heddles configured to guide first auxiliary warp yarns and define a first clamping zone along the weft axis, the first clamping zone being arranged within the main harness width. The weaving loom includes a first auxiliary shed mechanism configured to move the first auxiliary heddles.

[0019] The method includes, during a first weft insertion: opening a main shed of the main warp yarns by the main heddle moved by the main shed mechanism and opening a first auxiliary shed of the auxiliary warp yarns by the first auxiliary heddle moved by the first auxiliary shed mechanism; picking up a first weft yarn at the weft insertion position by the insertion device; pulling the first weft yarn from the weft insertion position into the main shed and into the first auxiliary shed by the insertion device; closing the first auxiliary shed by the first auxiliary heddle moved by the first auxiliary shed mechanism to clamp the first weft yarn in the first clamping zone by the first auxiliary warp yarns after the insertion device has pulled the first weft yarn through the first clamping zone and while the main shed is still open; releasing the first weft yarn by the insertion device; and closing the main shed by the main heddle.

[0020] Other optional features of the present invention are given below.

[0021] Preferably, during the first weft insertion, the first auxiliary shed mechanism closes the first auxiliary shed to clamp the first weft yarn after the insertion device has pulled the first weft yarn through the first clamping zone and while the insertion device is still pulling the first weft yarn into the main shed.

[0022] Preferably, the weaving loom comprises: a set of second auxiliary heddles configured to guide second auxiliary warp threads and define a second clamping zone along the weft axis, the second clamping zone being arranged within the width of the main harness cords; and a second auxiliary shed mechanism configured to move the second auxiliary heddles. Preferably, the first clamping zone is arranged between the weft insertion position and the second clamping zone. In this case, the method may comprise, during the first weft insertion: opening a second auxiliary shed by the second auxiliary heddles moved by the second auxiliary shed mechanism, wherein pulling the first weft by the insertion device comprises pulling the first weft into the second auxiliary shed; and closing the second auxiliary shed by the second auxiliary heddles moved by the second auxiliary shed mechanism to clamp the first weft in the second clamping zone by the second auxiliary warp threads when the insertion device has pulled the first weft into the second clamping zone and the main shed is still open and before the insertion device releases the first weft.

[0023] Preferably, the method further comprises, during the first weft insertion: after picking up the first weft, cutting the first weft along the weft axis by a given length equal to the distance from the first clamping zone to the second clamping zone.

[0024] Preferably, the method further comprises, during a second weft insertion performed after the first weft insertion: opening the main shed by the main heddles moved by the main shed mechanism and opening a first auxiliary shed by the first auxiliary heddles moved by the first auxiliary shed mechanism; picking up a second weft at the weft insertion position by the insertion device; pulling the second weft from the weft insertion position into the main shed and into the first auxiliary shed by the insertion device; closing the first auxiliary shed by the first auxiliary heddles moved by the first auxiliary shed mechanism to clamp the second weft in the first clamping zone by the first auxiliary warp threads when the insertion device has pulled the second weft past the first clamping zone and the main shed is still open; releasing the second weft by the insertion device; and closing the main shed by the main heddles. Preferably, opening the first auxiliary shed during the second weft insertion comprises: uncrossing any first auxiliary warp threads that cross around the first weft during the first weft insertion such that at the end of the second weft insertion, the first weft and the second weft are stacked together without being separated by any first auxiliary warp threads.

[0025] Preferably, the weaving loom comprises: a set of third auxiliary heddles configured to guide third auxiliary warp threads and define a third clamping zone along the weft thread axis, the third clamping zone being arranged within the width of the main harness cords; and a third auxiliary shed mechanism configured to move the third auxiliary heddles. Preferably, the method further comprises, during an intermediate weft insertion performed after the first weft insertion: opening a main shed by main heddles moved by a main shed mechanism such that a first weft thread is located above or below the main shed; picking up an intermediate weft thread at a weft insertion position by an insertion device; pulling the intermediate weft thread from the weft insertion position into the main shed by the insertion device; releasing the intermediate weft thread by the insertion device; and closing the main shed by main heddles moved by the main shed mechanism such that the first weft thread and the intermediate weft thread are stacked in the same weft insertion stack. Preferably, the method further comprises, during a third weft insertion performed after the intermediate weft insertion: opening the main shed by main heddles moved by the main shed mechanism and opening a third auxiliary shed of third auxiliary warp threads by third auxiliary heddles moved by a third auxiliary shed mechanism such that the intermediate weft thread is located between the first weft thread and the main shed; picking up a third weft thread at a weft insertion position by an insertion device; pulling the third weft thread from the weft insertion position into the main shed and into the third auxiliary shed by the insertion device; closing the third auxiliary shed by the third auxiliary heddles moved by the third auxiliary shed mechanism to clamp the third weft thread in the third clamping zone by the third auxiliary warp threads after the insertion device has pulled the third weft thread through the third clamping zone and the main shed is still open; releasing the third weft thread by the insertion device; and closing the main shed by the main heddles such that the first weft thread, the intermediate weft thread and the third weft thread are stacked in the same weft insertion stack and the intermediate weft thread is located between the first weft thread and the third weft thread.

[0026] Preferably, the method comprises, during the intermediate weft insertion: holding the first auxiliary heddles above the weft thread axis; and holding the third auxiliary heddles below the weft thread axis.

[0027] Preferably, the method comprises, during the intermediate weft insertion: opening a first auxiliary shed by first auxiliary heddles moved by a first auxiliary shed mechanism such that the intermediate weft thread is inserted into the first auxiliary shed by the insertion device; and / or opening a third auxiliary shed by third auxiliary heddles moved by a third auxiliary shed mechanism such that the intermediate weft thread is inserted into the third auxiliary shed by the insertion device.

[0028] Preferably, the method comprises, during the first weft insertion: increasing the tension of the first auxiliary warp threads and simultaneously closing the first auxiliary shed to clamp the first weft thread by the tensioned first auxiliary warp threads. Description of the Drawings

[0029] The present invention will be better understood based on the following description given in correspondence with the drawings and as illustrative examples which are not limiting of the subject matter of the invention. In the drawings:

[0030] - Figure 1 is a perspective view of a knitting loom according to the present invention.

[0031] - Figure 2 is Figure 1 a partial perspective view of a part of the knitting loom.

[0032] - Figure 3 is Figure 2 a partial perspective view of a detail of the knitting loom.

[0033] - Figure 4 is Figures 1 to 3 a schematic view of a part of the knitting loom, showing a partial longitudinal section of a multi-layer fabric woven by the knitting loom.

[0034] - Figure 5 is Figures 1 to 4 a composite view of a part of the knitting loom, showing a top view of a multi-layer fabric woven by the knitting loom at the top, a transverse section of the woven fabric at the bottom, and the fabric at the bottom is shown at the same scale and positioned at the same coordinates along the direction Y1.

[0035] - Figure 6 is Figures 1 to 5 a schematic view of the trajectory of a moving heddle of the knitting loom.

[0036] - Figures 7 to 11 is a schematic perspective view of another embodiment of a multi-layer fabric according to the present invention during successive steps of a method that can be implemented with the Figures 1 to 6 knitting loom.

[0037] - Figure 12 is Figures 7 to 11 a schematic perspective view of a detail of the multi-layer fabric.

[0038] - Figure 13 is a schematic side view of a detail of another embodiment of a multi-layer fabric according to the present invention. DETAILED DESCRIPTION

[0039] Figures 1 to 3 shows a knitting loom 2 according to the present invention. The loom 2 is used to weave warp and weft yarns together to form a multi-layer fabric 1 composed of continuous woven yarns, as Figure 4 and Figure 5 shown more specifically.

[0040] As Figure 4 and Figure 5 shown, the multi-layer fabric 1 includes the woven weft yarns shown in cross-section in Figure 4 and the Figure 5The warp yarns shown in cross-section. The fabric 1 defines a warp direction X1, a weft direction Y1, and a layer direction Z1. The warp yarns are generally oriented along the warp direction X1. The weft yarns are generally oriented along the weft direction Y1.

[0041] The multi-layer fabric 1 can be a qualified technical fabric. Preferably, the multi-layer fabric 1 is configured to form a three-dimensional preform for manufacturing a three-dimensional component of a composite material, which includes the preform impregnated with a reinforcing resin or the like. The manufactured component can be a fan blade or the like.

[0042] In Figure 4 is shown the multi-layer fabric 1 during weaving. In this case, the unfinished fabric 1 includes a cloth fell 3, i.e., the front edge where the yarns are woven and which is oriented parallel to the direction Y1.

[0043] As Figure 4 and Figure 5 shown, the multi-layer fabric 1 includes a plurality of successive layers that are oriented parallel to the directions X1 and Y1 and distributed parallel to the direction Z1, each layer being formed by woven weft and warp yarns, and adjacent layers being interwoven by the interlacing of the warp and weft yarns of said layers. In Figure 4 and Figure 5 example, the layers L0, L1, L2, L3, L4, L5, and L7 of the fabric 1 are identified.

[0044] In the multi-layer fabric 1, the weft yarns included at a given layer can have a length different from the length of the weft yarns included at a subsequent layer. For example, as Figure 5 shown, the weft yarn 100 of layer L0 is shorter than the weft yarn of layer L2 below layer L0. Thus, the multi-layer fabric 1 can be shaped to form a near-net preform.

[0045] The multi-layer fabric 1 includes successive weft insert stacks that are oriented parallel to the directions Y1 and Z1 and distributed parallel to the direction X1, each weft insert stack being formed by woven weft and warp yarns, and adjacent weft insert stacks being interwoven by the interlacing of the warp and weft yarns of said weft insert stacks. In Figure 4 is identified the weft insert stack P1, which includes six superposed weft yarns. The weft insert stack P1 is located at the cloth fell 3. In Figure 4 is shown the successive weft insert stack P2.

[0046] A yarn creel including yarn packages, or a warp beam creel, or any other warp delivery unit, supplies warp yarns to a loom 2. The warp yarns to be supplied to the loom enter the fabric 1 at the fabric strip 3. The warp delivery unit is located in a direction opposite to the direction X1 relative to the fabric 1. A fabric beam or any other receiving unit (not shown) is arranged in the direction X1 relative to the delivery unit for receiving the fabric 1 woven by the loom 2 at the edge of the fabric 1 opposite to the fabric strip 3.

[0047] The loom 2 includes a main harness 11 and auxiliary harnesses, and the auxiliary harnesses include Figure 4 and Figure 5 the shown auxiliary harnesses 21, 31 and 41. The main harness 11 and the auxiliary harnesses 21, 31, 41 are positioned between the warp delivery unit and the fabric strip 3 in a direction opposite to the direction X1 relative to the fabric strip 3. The main harness 11 is configured to guide the main warp yarns 12 supplied by the warp delivery unit to the fabric strip 3, particularly along a vertical path to the fabric strip 3. The auxiliary harnesses are configured to guide the auxiliary warp yarns supplied by the warp delivery unit to the fabric strip 3, particularly along a vertical path to the fabric strip 3. The main warp yarns may also be referred to as "product warp yarns". The auxiliary warp yarns may also be referred to as "processing warp yarns" or "processing and product warp yarns".

[0048] In particular, the auxiliary harnesses 21, 31 and 41 respectively guide the auxiliary warp yarns 22, 32 and 42, as Figure 4 and Figure 5 shown. For this purpose, each main harness 11 includes a main eyelet 13 that receives the main warp yarn 12 moved by the harness 11. Each auxiliary harness, such as the harness 21, includes an auxiliary eyelet, such as the auxiliary eyelet 23, which receives the auxiliary warp yarn, such as the warp yarn 22 moved by the harness 21.

[0049] The main harness 11 can selectively reciprocate along a path parallel to the direction Z1 (here a vertical path) to successively open and close the main shed 14 of the main warp yarns 12 during successive weaving pickings.

[0050] The opening of the main shed 14 is achieved by the main harness 11 selectively pulling each main warp yarn 12 upward or downward from the crossover position. The closing of the main shed 14 is achieved by the main harness 11 selectively pulling the main warp yarns 12 back to the crossover. At each picking, depending on the intended weaving, the opened main shed 14 can have a shape different from the shape it had during the previous picking, i.e., it can mean different combinations of pulling the main warp yarns 12 upward and pulling the main warp yarns 12 downward.

[0051] The main harness 11 is distributed along the width W11 of the main harness along the weft axis Y90, as Figure 5 schematically shown.

[0052] The main heddle width W11 corresponds to the distance between two extreme main heddles 11 measured along the weft axis Y90, or the distance between two extreme main warp threads 12. The main heddle width W11 also corresponds to the maximum width of the fabric that can be woven by the loom 2 parallel to the weft direction Y1.

[0053] The weft axis Y90 is parallel to the weft direction Y1. As Figure 4 schematically shown, the fabric strip 3 is positioned relative to the weft axis Y90 in the direction X1, and the weft axis Y90 is parallel to the weft direction Y1 and positioned relative to the main heddles 11 in the direction X1.

[0054] The main heddles 11 are moved, i.e., actuated by the main shed mechanism 15 of the loom 2, as Figure 1 seen. The main shed mechanism 15 is positioned relative to the heddles 11 in the direction Z1, i.e., positioned above the heddles 11. In order to be actuated, the main heddles 11 are connected to the shed mechanism 15 by the main heddle wires 16 of the loom 2. The main heddle wires 16 include a plurality of heddle wire bundles, and each heddle wire bundle connects one or a group of heddles 11 to the shed mechanism 15. Advantageously, the heddle wires 16 include a main eyelet board 17 disposed between the main shed mechanism 15 and the main heddles 11. Each main heddle 11 passes through a corresponding hole of the eyelet board 17 so as to be guided by the eyelet board 17. Thus, the eyelet board 17 ensures correct positioning and guides the movement of the heddles 11. Preferably, the eyelet board 17 is oriented parallel to the directions Y1 and X1.

[0055] The main shed mechanism 15 is of the jacquard type. In other words, the mechanism 15 is capable of actuating each main heddle 11 or multiple groups of main heddles 11 in a sequence independent of the sequences of the other heddles 11 or groups of heddles 11, according to a user-defined non-repeating sequence. Preferably, the main shed mechanism 15 is a mechanical or electronic jacquard machine. Generally, this type of shed mechanism is specifically capable of driving the main heddles according to a ring-bell profile, or at least capable of programming the movement of the heddles to a limited number of different positions, such as a top position, a bottom position, and sometimes an intermediate position (especially for superimposed rapier applications), according to a fixed movement pattern. In a preferred embodiment, the main shed mechanism 15 includes selectable hooks, each hook or pair of hooks driving a single main heddle 11 or a group of main heddles 11. Each main heddle 11 or group of main heddles 11 is suspended from a hook or a pair of hooks by one of the bundles in the bundle of main connecting threads 16. The hooks are selectively suspended, for example, by electromagnetic selection means on two parallel blades of the main shed mechanism 15 parallel to the weft direction Y1. Each blade is actuated according to an opposite reciprocating motion to drive the selectable hooks between an upward position and a downward position. The main shed mechanism 15 also includes a common main shaft or actuator for driving the blades. This main shaft is synchronized with the main shaft of the weaving loom. In this embodiment where the main shed mechanism 15 includes a single actuator for selectively driving the main heddles, the mechanism 15 has a lower cost and less complexity compared to shed mechanisms that imply the heddles are actuated by several separate actuators.

[0056] The auxiliary heddles are distributed in separate groups. For example, eight groups of auxiliary heddles can be implemented for the loom 2, including the auxiliary heddle group 21, the auxiliary heddle group 31, and the auxiliary heddle group 41, and the auxiliary heddle groups include several auxiliary heddles. Preferably, each group of auxiliary heddles includes at least three auxiliary heddles. Preferably, each group of auxiliary heddles includes fewer than twenty auxiliary heddles, preferably fewer than ten auxiliary heddles, preferably fewer than five auxiliary heddles, and preferably exactly three auxiliary heddles.

[0057] For each group, the auxiliary heddles can be selectively reciprocated along a path parallel to the direction Z1 (here a vertical path) to successively open and close the auxiliary shed of the auxiliary warp yarns during each successive weaving pick. Each auxiliary shed corresponds to a group of auxiliary heddles and is always associated with the same group of auxiliary warp yarns. As Figure 4 shown, the auxiliary heddles 21 open and close the auxiliary shed 24 of the auxiliary warp yarns 22.

[0058] The opening of the auxiliary shed is achieved by its corresponding set of auxiliary heddles. These auxiliary heddles selectively pull each auxiliary warp yarn of the set upward or downward from the crossover position. The closing of the auxiliary shed is achieved by selectively pulling the auxiliary warp yarns of the set back to the crossover by the set of auxiliary heddles. At each weft insertion, for a given set, the opened auxiliary shed can have a shape different from the shape it had during the previous weft insertion, i.e., it means different combinations of pulling the auxiliary warp yarns upward and downward according to the intended weaving.

[0059] For each set, the auxiliary heddles are distributed along the clamping zone along the weft axis Y90, as Figure 5 schematically shown. In particular, the auxiliary heddle 21 defines the clamping zone W21, the auxiliary heddle 31 defines the clamping zone W31, and the auxiliary heddle 41 defines the clamping zone W41. Along each clamping zone, the auxiliary heddles of the same set are grouped together such that each clamping zone is smaller than the width W11 of the main heddle wire, for example, between one tenth and one thousandth of the size of the width W11 of the main heddle wire, or even smaller. Preferably, for each set, the auxiliary heddles are directly adjacent to each other. For each set, the clamping zone corresponds to the distance between two extreme auxiliary heddles measured along the weft axis Y90, or the distance between two extreme auxiliary warp yarns of the set.

[0060] Each clamping zone is completely arranged within the width W11 of the main heddle wire, i.e., it only covers a small part of the width W11 of the main heddle wire and does not extend beyond the ends of the width W11 of the main heddle wire. The clamping zones can be separated from each other, can overlap or be superposed. For example, the clamping zone W21 is separated from the clamping zone W31 along the weft axis Y90. The clamping zones W31 and W41 are superposed along the weft axis Y90.

[0061] For each set, the auxiliary heddles are moved, i.e., actuated by the corresponding auxiliary shed mechanism of the loom 2. The auxiliary shed mechanism can be controlled by the same main control unit as the main shed mechanism, or by a separate auxiliary control unit synchronized with the main control unit of the loom 2.

[0062] As Figure 3 seen, the auxiliary heddle 21 is moved by the auxiliary shed mechanism 25, the auxiliary heddle 31 is moved by the auxiliary shed mechanism 35, and the auxiliary heddle 41 is moved by the auxiliary shed mechanism 45. For each set, the auxiliary shed mechanism is positioned along the direction Z1 relative to the auxiliary heddles it drives. In order to be actuated, the auxiliary heddles are connected to the shed mechanism of the relevant set by the corresponding auxiliary heddle wires of the loom 2. For example, the heddle 21 is driven by the auxiliary heddle wire 26, the heddle 31 is driven by the auxiliary heddle wire 36, and the heddle 41 is driven by the auxiliary heddle wire 46. Each auxiliary heddle wire includes a plurality of heddle wire bundles, and each heddle wire bundle connects one or a group of auxiliary heddles of the relevant set to the shed mechanism of the same set. As Figure 5As shown, advantageously, the main heddle board 17 is combined with auxiliary heddle boards (including auxiliary heddle boards 27 and 37). For each group, each auxiliary harness passes through a corresponding hole of an auxiliary heddle board and is thus guided. Therefore, the auxiliary heddle board ensures the correct positioning and guiding of the auxiliary harness and its harness cord bundle. Preferably, each group of auxiliary harnesses is held by only one auxiliary heddle board. One auxiliary heddle board can hold multiple groups of auxiliary harnesses. For example, all of the auxiliary harnesses 21 pass through the auxiliary heddle board 27, while all of the auxiliary harnesses 31 and 41 pass through the corresponding parts of the auxiliary heddle board 37. Here, the harnesses 31 and 41 share the heddle board 37.

[0063] The positioning of the auxiliary heddle board defines the position of the corresponding clamping area, as Figure 5 shown. For example, the auxiliary heddle board 27 is located along the axis Y90 at the same position as the clamping area W21.

[0064] As Figure 5 shown, each auxiliary heddle board can be detachably or permanently attached to the edge of the main heddle board 17. The advantage of this embodiment is the ability to add and / or remove auxiliary heddle boards according to the need for groups of auxiliary harnesses, and / or adjust the position of the auxiliary heddle boards. Alternatively, the auxiliary heddle board can be integrated into the main heddle board, i.e., all main and auxiliary harnesses pass through a single common heddle board.

[0065] As Figure 3 shown, each auxiliary shed mechanism preferably includes a main actuator 81 and a secondary actuator 82, which have independent structures and can be independently controlled to produce actuations that are independent of each other and independent of the actuators of other auxiliary shed mechanisms. Preferably, each actuator 81 and 82 is an electric servo motor. Specifically, each of the actuators 81 and 82 preferably includes a stator 83 and a pulley 84, and the pulley is mounted on the rotor of the actuator and is rotatably driven relative to the rotor by the electromagnetic interaction between the stator 83 and the rotor under power supply and control.

[0066] Each pulley 84 drives at least one auxiliary harness cord bundle, preferably three harness cord bundles, to drive three corresponding auxiliary harnesses. Preferably, each actuator of the auxiliary mechanism drives three or more auxiliary harnesses, thus driving a large number of auxiliary sheds to satisfactorily clamp the inserted weft yarn, as described below.

[0067] For each group, the auxiliary harness is composed of a main auxiliary harness and a secondary auxiliary harness. The main auxiliary harness is driven by the main actuator 81, and the secondary auxiliary harness is driven by the secondary actuator 82. For example, in Figure 4In this case, the left auxiliary heald 21 is one of the main auxiliary healds, and the right auxiliary heald 21 is one of the secondary auxiliary healds in the heald 21 group. For each group, the main auxiliary heald is driven according to the main reciprocating motion to form the main side of the auxiliary shed, such as the top of the shed, while the secondary auxiliary heald is driven according to the secondary reciprocating motion to form the opposite side of the auxiliary shed, such as the bottom of the shed. The secondary reciprocating motion is opposite to the main reciprocating motion. Since the main auxiliary heald and the secondary auxiliary heald are driven by two independent actuators 81 and 82, the intersection point of the reciprocating motions of the main auxiliary heald and the secondary auxiliary heald can be adjusted as needed during weaving.

[0068] Alternatively, each auxiliary shed mechanism may have only one actuator including a stator and a pulley, and the pulley drives the main auxiliary heald and the secondary auxiliary heald. In this case, the intersection point is in a fixed position during weaving.

[0069] Alternatively, the first auxiliary warp yarn guided by the first auxiliary heald (the first auxiliary heald is driven by the actuator of the auxiliary mechanism) may form an auxiliary shed with the main warp yarn, so that after the inserting device pulls the weft yarn through the clamping zone, the auxiliary warp yarn can move towards the main warp yarn to clamp the weft yarn in the clamping zone.

[0070] In any case, the loom 2 preferably includes a relatively small number of actuators, that is, the main actuator of the main shed mechanism, and some more actuators for the auxiliary shed mechanism.

[0071] Each bundle of auxiliary harness cords can drive more than one auxiliary heald, so that less than three bundles can be implemented for each actuator 81 and 82, although actually more auxiliary healds are driven. More generally, more than three or less than three bundles of auxiliary harness cords can be driven by each of the actuators 81 and 82. Additionally, more than three or less than three auxiliary healds can be driven by each of the actuators 81 and 82.

[0072] Alternatively, the pulley 84 of the actuator 81 or 82 drives an auxiliary bundle, and the auxiliary bundle drives two or more auxiliary healds connected to the auxiliary harness cord bundle, so that the pulley drives a corresponding group of auxiliary healds, and the group of auxiliary healds guides the auxiliary warp yarn with a similar reciprocating motion. For example, the upper plastic coupler (not shown) includes two housings to accommodate a pair of corresponding adjacent upper limit ends of the auxiliary healds.

[0073] Alternatively, two or more auxiliary heddles are connected below their eyelets to a connection device, not shown, such as a lower plastic connector having a vertical receiving groove for receiving the respective adjacent lower limit ends of the auxiliary heddles and having a groove for connecting a bundle, such that the auxiliary heddles can benefit from a similar return device, such as a return device with a strong load. Advantageously, the bundle can be connected to the lower plastic connector with a knot, such that the height of the auxiliary heddles and the eyelets can be set as required.

[0074] The heddles are pulled back by well-known return devices, such as weights or elastic devices (e.g., vertical springs connected to a fixed frame at the bottom of the machine).

[0075] In another alternative, two adjacent springs can be replaced by a single spring connected to a lower plastic connector, not shown.

[0076] As Figure 3 shown, preferably, the loom includes two beams 85 and 86 oriented parallel to the direction Y1. Preferably, the beams 85 and 86 are arranged close to the main harness cords 16 to obtain a minimum angle for the bundles of auxiliary harness cords. More precisely, parallel to the direction Y1, the beams 85 and 86 are advantageously positioned corresponding to the width W11 of the main harness cords. Preferably, the beams 85 and 86 are positioned along the direction Z1 relative to the main reed 17 and / or the auxiliary reed. Advantageously, the beams 85 and 86 are connected to the fixed part of the loom 2 by rotary connectors, such that the beams 85 and 86 can be rotated away from the main harness cords 16 for maintenance or inspection.

[0077] Each auxiliary shed mechanism is supported by one of the beams 85 and 86. As Figure 3 shown, the mechanisms 25 and 35 are supported by the beam 85, while the mechanism 45 is supported by the beam 86. In this example, each beam supports a total of four auxiliary shed mechanisms accordingly. Parallel to the direction Y1, each auxiliary shed mechanism is generally positioned corresponding to the clamping zone defined by the auxiliary heddles driven by the relevant auxiliary shed mechanism to obtain a minimum angle for the bundles of auxiliary harness cords.

[0078] During the use of the loom 2, each auxiliary shed mechanism is fixedly supported by its beam. Before weaving, the position of each auxiliary shed mechanism can be adjusted along the supporting beam so as to adjust the position of the shed mechanism in a manner parallel to the weft axis Y90. In addition, before weaving, each auxiliary shed mechanism can be removed from the beam, or additional auxiliary shed mechanisms can be added to the beam. Therefore, according to the fabric to be obtained or according to the process of operating the fabric, the corresponding group of auxiliary heddles can be conveniently removed or added to the loom 2. Therefore, the auxiliary heddles and the shed mechanisms are highly versatile. Moreover, the auxiliary shed mechanisms can be easily set up on an existing loom.

[0079] Preferably, two auxiliary shed mechanisms 35 and 45 are respectively distributed at corresponding positions on two beams 85 and 86 along axis Y90, so as to be able to share the auxiliary harness board 37 and define overlapping clamping zones W31 and W41. In Figure 3 and Figure 5 the example of, eight auxiliary shed mechanisms actually define four pairs of shed mechanisms distributed parallel to the weft axis Y90, wherein, for each pair of auxiliary shed mechanisms, one auxiliary shed mechanism is supported by beam 85 and the other auxiliary shed mechanism is supported by beam 86. For each pair of auxiliary shed mechanisms, the auxiliary heddles driven by this pair of auxiliary shed mechanisms share the same auxiliary harness board and define overlapping clamping zones. Therefore, in this example, only four clamping zones can be defined, and each clamping zone is associated with two groups of auxiliary heddles. This principle can be applied regardless of the number of groups of auxiliary heddles and auxiliary shed mechanisms.

[0080] Alternatively, only one beam can be implemented to support all the auxiliary shed mechanisms. Alternatively, more than two beams can be implemented such that the auxiliary shed mechanisms have any suitable distribution on the beams.

[0081] The loom 2 includes a single rapier system or any other suitable insertion device 90 to insert the weft yarn into the opened main shed and auxiliary sheds of the main warp yarns and auxiliary warp yarns, thereby weaving the fabric 1. The insertion device 90 is arranged along the weft axis Y90 of the loom 2. In this example, the insertion device 90 is a single rapier system including a rapier 91, as Figure 5 schematically shown in. In the case of a single rapier system, a single weft yarn is inserted during each weft insertion. In the case of a double rapier or multi-rapier, multiple new weft yarns can be inserted in parallel during each weft insertion.

[0082] The insertion device 90 is configured to: pick up a new weft yarn to be woven in during each weft insertion, that is, in each weaving cycle. For example, pick up a new weft yarn 100 from the weft yarn conveying unit 94. The weft yarn 100 is picked up at the weft insertion position P94 along the weft axis Y90. As Figure 5 shown, the weft insertion position P94 is located outside the width W11 of the main harness cords, that is, beside the main shed 14 of the main warp yarns 12 in the direction Y1. In order to pick up the weft yarn 100, the rapier 91 is preferably provided with Figure 5 the wire clip 92 schematically shown in.

[0083] In Figure 1An example of a weft yarn delivery unit 94 is shown, which is configured to deliver a new weft yarn to be picked up at the weft insertion position P94. Preferably, the unit 94 includes different weft yarn bobbins, each weft yarn bobbin including a weft yarn having a given type of reinforcing fiber (such as carbon, Kevlar, aramid, or glass), or a weft yarn having a different nominal diameter. In this case, the weft yarn delivery unit 94 may include a weft yarn selector, so that the required weft yarn can be picked up each time a weft is inserted.

[0084] The insertion device 90 is configured to: pull the weft yarn 100 along the weft yarn axis Y90 from the weft insertion position P94 by translating the front extreme end of the weft yarn 100 in a direction opposite to the direction Y1 through any warp shed opened around the axis Y90. As Figure 5 shown, the rapier 91 is pulled in a direction opposite to the direction Y1, and the thread gripper 92 holds the front extreme end of the weft yarn 100. The trajectories of the rapier 91 and the weft yarn 100 are along the axis Y90.

[0085] The insertion device 90 includes cutting means 93, such as scissors arranged along the axis Y90, which are located outside the width W11 of the main heddle and on the same side as the weft insertion position P94. During or after the pulling, the pulled weft yarn 100 is cut to an appropriate length by the cutting means 93. For different positions of the rapier 91 along the weft yarn axis Y90, the length of the pulled weft yarn can be changed by cutting the weft yarn 100 from the delivery unit 94.

[0086] After the pulling, the insertion device 90 releases the weft yarn 100 at a given position along the weft yarn axis Y90, for example, Figure 5 releases the weft yarn 100 at the position P91 shown. At this given release position P91, the pulled weft yarn 100 is completely arranged within the width W11 of the main heddle. In particular, the two weft ends of the weft yarn 100 are arranged within the width W11 of the main heddle. To release the weft yarn 100, the thread gripper 92 is opened. Releasing the weft yarn 100 determines the future position of the weft yarn 100 in the fabric 1 parallel to the direction Y1.

[0087] These sub-steps including picking up, pulling, and releasing constitute the step of inserting the weft yarn into the opened warp shed.

[0088] Advantageously, the loom 2 includes a reed 95 driven by a reed base (not shown), which can move between the heddles and the fabric strip 3. In Figure 4 it, the reed 95 is shown in its initial position, which is shown by a continuous line, and the beating position of the reed 95 is shown by a dashed line. The reed 95 is configured to beat the inserted weft yarn 100 against the fabric yarn 3 at the end of each weft insertion to set the position of the weft yarn 100 relative to the fabric 1 along the direction X1.

[0089] AsFigure 5 As shown, each weft insertion stack of fabric 1 includes a main part 111. The main part 111 includes woven weft yarns and main warp yarns 12, and there are no auxiliary warp yarns. In other words, auxiliary warp yarns are not woven in the main part 111 of fabric 1. The main part 111 is woven by main heddles 11 and a main shed mechanism 15.

[0090] In addition, for at least some of the weft insertion stacks of fabric 1, such as Figure 5 the weft insertion stack shown, fabric 1 includes clamping parts, such as Figure 5 the clamping parts 112, 113, and 114 shown. Each clamping part is adjacent to the main part 111 and is formed on one of the clamping zones. For example, the clamping part 112 is formed at the clamping zone W21, the clamping part 113 is formed at the clamping zone W31, and the clamping part 114 is formed at the clamping zone W41. Each clamping part includes woven weft yarn extreme ends and auxiliary warp yarns, and preferably no main warp yarns. In particular, the clamping part 112 is woven by the auxiliary warp yarn 22 through the heddle 21 and the mechanism 25, the clamping part 113 is woven by the yarn 32, the heddle 31, and the mechanism 35, and the part 114 is woven by the yarn 42, the heddle 41, and the mechanism 45.

[0091] When the extreme ends of one weft yarn or a plurality of successive weft yarns cannot reach the ends of the main harness width W11, each clamping part is formed at the extreme end of one weft yarn or a plurality of successive weft yarns. In other words, for at least one extreme end of the weft yarn, when the relevant weft yarn is shorter than the main harness width, a clamping part is formed. If the other extreme ends of the weft yarn reach the other extreme ends of the main harness width W11, no clamping part is formed at the extreme end of the main part 111. Each clamping part is formed for only one layer, or for a plurality of successive layers, for which the weft yarn extreme ends are positioned at the same position along the axis Y90, that is, in the same clamping zone. One clamping part can group together the extreme ends of a plurality of successive weft yarns located at the same position along the weft yarn axis Y90.

[0092] In each layer including two clamping parts, the main part 111 does not extend beyond the clamping parts, but only extends between the clamping parts. For example, in layer L0, the clamping parts 112 and 113 are woven on both sides of the main part 111, and the main part 111 only extends between the clamping parts 112 and 113.

[0093] In each layer including only one clamping part, the main part 111 extends to the other end of the main harness width W11. For example, the clamping part 115 forms the left end of layer L2, and the main part 111 extends from the clamping part 115 to the opposite end of layer L2, and the opposite end is located at a position corresponding to the end of the main harness width W11.

[0094] In each layer where the weft yarn has the same length as the width W11 of the lease rod, no clamping portion is provided, and the main portion extends from one end to the other end of the relevant layer.

[0095] Preferably, auxiliary heddles such as heddles 31 and 41, which are related to two clamping portions overlapping or stacked in the same clamping zone but are related to the opposite side of the fabric 1 with respect to the direction Z1, are held by the same auxiliary dobby (here, for example, dobby 37). Preferably, auxiliary shedding mechanisms for the clamping portions dedicated to the upper side of the fabric 1, such as mechanisms 25 and 35, are supported by the upper beam 85, while an auxiliary shedding mechanism for the clamping portion dedicated to the lower side of the fabric 1, such as mechanism 45, is supported by the lower beam 86.

[0096] Since the clamping portion is woven by a shedding mechanism and auxiliary heddles separate from the main shedding mechanism, it is easy to select different types of yarns, different weaving patterns, and / or weaving parameters for the clamping portion that are different from those for the main portion. Advantageously, inexpensive polypropylene yarn can be used as the auxiliary warp yarn to optimize the clamping function of the auxiliary warp yarn on the main warp yarn, rather than using expensive carbon warp yarn materials that are only available as main warp yarns.

[0097] The loom 2 is capable of performing a method for weaving a multi-layer fabric 1.

[0098] The loom 2 is configured to achieve multiple successive weft insertions, each weft insertion corresponding to weaving an additional weft yarn into the fabric 1.

[0099] During successive weft insertions, the loom 2 is configured to achieve a weft insertion represented as the "first weft insertion", as Figures 4 to 6 shown.

[0100] Figure 6 The movement trajectories of the main heddle 11 and the auxiliary heddles 21 and 31 are shown.

[0101] In Figure 6 , the horizontal axis represents the rotation angle θ of the main shaft of the main shedding mechanism 15. During a single weft insertion, the main shaft rotates one full turn, that is, from 0° (degrees) at the start of the first weft insertion to 360° at the end of the first weft insertion. Figure 6 Two complete successive weft insertions are shown, including the first weft insertion on the left.

[0102] In Figure 6 , the vertical axis represents the position Z of the relevant heddle parallel to the direction Z1, where 0 represents the crossing point position.

[0103] In Figure 6In it, curve G11 represents the main heddle 11. Curve G21 represents the auxiliary heddle 21. Curve G31 represents the auxiliary heddle 31. Line G100 represents the insertion of the weft yarn 100 into the shed through the insertion device 90. The starting point of line G100 represents the moment when the insertion device just picks up the weft yarn 100. The thickness of line G100 symbolically represents the configuration of the auxiliary shed for clamping the weft yarn 100. The end of line G100 represents the end of the weft insertion.

[0104] The symbol "IV" represents the timing corresponding to Figure 4 and Figure 5 the top view.

[0105] The auxiliary heddles 21 and 31 are distributed on the axis Y90 such that the clamping zone W21 is arranged between the clamping zone W31 and the weft insertion position P94. These two clamping zones W21 and W31 are separated along the axis Y90, so that a plurality of main warp yarns 12 and the corresponding main heddles 11 are arranged between the auxiliary warp yarns 22 moved by the heddle 21 and the auxiliary warp yarns 32 moved by the heddle 31.

[0106] As Figure 6 shown by the curve G11 in, during the initial step S1, starting from θ = 0°, the main shed 14 is opened by the main heddle 11 moved by the main shed mechanism 15. The opening of the main shed 14 is maximum at θ = 180°. Figure 6 The label S1 in represents the start time of step S1.

[0107] In another step S6 after step S1, starting from θ = 180°, the main shed 14 is closed by the main heddle 11 moved back by the main shed mechanism 15. The closing of the main shed 14 is achieved at θ = 360°. The opening and closing trajectories of the main heddle 11 are preferably bell-shaped trajectories, as Figure 6 shown, that is, sine curve trajectories.

[0108] As Figure 6 shown by the curve G21 in, during step S1, starting from θ = 0°, the auxiliary shed 24 is opened by the auxiliary heddle 21 moved by the corresponding auxiliary shed mechanism 25. The opening of the auxiliary shed 24 is interrupted before θ = 180°. Here, the opening of the auxiliary shed 24 is interrupted approximately at θ = 120°. This value depends on the position of the clamping zone W21 along the weft axis Y90. The closer the clamping zone W21 is to the weft insertion position P94, the smaller the angle for interrupting the opening of the heddle 21. In another step S4 executed after step S1 but before step S6, starting from θ = 120°, the auxiliary shed 24 is closed by the auxiliary heddle 21 moved back by the relevant auxiliary shed mechanism 25. The closing of the auxiliary shed 24 is achieved before the main heddle 11 closes the main shed 14, or even before the main heddle 11 starts to close the main shed 14.

[0109] As Figure 6 shown by curve G31 in, during step S7, starting from θ = 0°, the auxiliary shed of the auxiliary warp yarn 32 is opened by the auxiliary heddles 31 moved by the corresponding auxiliary shedding mechanism 35. The opening of this auxiliary shed is interrupted before θ = 180°. Here, the opening of this auxiliary shed is interrupted approximately at θ = 160°. This value depends on the position of the clamping zone W31 along the weft axis Y90. The closer the clamping zone W31 is to the weft insertion position P94, the smaller the angle for interrupting the said opening. In step S9, which is performed after step S7 but before step S6, starting from θ = 160°, this auxiliary shed is closed by the auxiliary heddles 31 moved back by the relevant auxiliary shedding mechanism 35. The closing of this auxiliary shed is achieved before the main heddles 11 close the main shed 14, or even before the main heddles 11 start to close the main shed 14. The closing of the auxiliary shed of the auxiliary warp yarn 32 is achieved after the closing of the auxiliary shed 24 of the warp yarn 22. Alternatively, the opening or closing of the auxiliary shed occurs after 180°.

[0110] The auxiliary shedding mechanism including the actuators 81 and 82 defined above makes Figure 6 the opening and closing trajectories of the auxiliary shedding shown in different from the bell-shaped trajectory. Therefore, the closing of the auxiliary shed by the auxiliary heddles can be achieved at any desired time, especially before the main shed is closed by the main heddles. Closing the auxiliary shed means approaching, driving, or pulling two auxiliary warp yarns closer to the intersection point. In the case where there is a weft yarn in the auxiliary shed, the weft yarn is clamped. Depending on the thickness of the weft yarn, the shed remains slightly open around the weft yarn, making the shed "semi-closed". The term "closing" is intended to include such a slightly open or semi-open configuration.

[0111] During the above steps S1, S4, S6, S7, and S9, other auxiliary heddles are preferably closed and moved away from the intersection point so as not to interfere with the weaving of layer L0. For example, as Figure 6 shown by curve G41 in, when the main shed 14 is fully open, the auxiliary heddles 41 are located at the bottom position lower than the maximum position of the lower main heddles 11, so that the corresponding auxiliary shed is closed and arranged below the main shed 14. If there are other auxiliary heddles provided, such as the auxiliary heddles for forming the clamping part 115, then when the main shed 14 is fully open, the auxiliary heddles can also be positioned higher than the maximum position of the upper main heddles 11, as shown by curve G51.

[0112] In parallel with the steps S1, S4, S6, S7, and S9 performed by the heddles and the shedding mechanism, the insertion device 90 is configured to perform step S2 of picking up the weft yarn 100 at the weft insertion position P94. For example, this step S2 preferably starts at 100°.

[0113] Preferably, the step of selecting the desired weft yarn package by the weft selector of the conveying unit 94 is performed before step S2, and the weft yarn 100 will be picked up from this weft selector. In one embodiment, once the shed is fully opened by the heddles, after step S1 and before step S2, the actuator of the insertion device 90 causes the rapier 91 to rapidly translate along the weft axis Y90 to reach the weft insertion position P94. Then, step S2 includes picking up, that is, grasping the weft yarn 100 by the gripper 92. The picking up S2 is achieved slightly before the heddles 21 finish opening, that is, before S4 starts.

[0114] After the picking up S2, the insertion device 90 immediately starts step S3, that is, pulling the picked up weft yarn 100 along the weft axis Y90 in a direction opposite to the direction Y1. For this purpose, for example, the rapier 91 is pulled by the actuator in a direction opposite to the direction Y1, so as to pull the weft yarn 100 by clamping the extreme end of the weft yarn 100 in the gripper 92.

[0115] During the pulling, the weft yarn 100 first passes through the clamping zone W21, that is, is inserted into the auxiliary shed 24 of the auxiliary warp yarns 22 opened by the heddles 21. During the weft yarn 100 passing through the auxiliary shed 24, the step S4 of closing the shed 24 is started, so that once the front end of the weft yarn 100 and the rapier 91 come out of the clamping zone W21, the auxiliary shed 24 is preferably closed. Therefore, the closing of the auxiliary shed 24 is performed before the main shed 14 is closed and before the weft yarn 100 is fully pulled, so as to clamp the weft yarn 100 by the auxiliary warp yarns 22, that is, guide the translation of the weft yarn 100 at the clamping zone W21. The weft yarn 100 is clamped and is precisely guided and positioned during the pulling. In other words, the weft yarn is fixed when the main shed is opened, or is also fixed before the shed is closed. In other words, before the main shed is closed, the weft yarn is stabilized in place. In other words, the auxiliary shed 24 of the auxiliary warp yarns 22 predicts the movement of the main warp yarns 12 during weft insertion, just like the main warp yarns will close the main shed for a period of time after the insertion device releases the weft yarn, which is beneficial to obtaining a reliable position of the inserted weft yarn in the fabric 1. In other words, due to the auxiliary warp yarns in the clamping zone, the inserted weft yarn can be kept stretched in the fabric.

[0116] Preferably, the tension of the auxiliary warp yarns 22 is increased and the auxiliary shed 24 is closed simultaneously, so as to clamp the weft yarn 100 more strongly by the tensioned auxiliary warp yarns 22. The increase in tension can be obtained by the warp yarn conveying device, by the fabric beam or by an additional mechanism that can be programmed.

[0117] As the auxiliary shed 24 is closed, the pulling S3 of the weft yarn 100 continues, causing the weft yarn 100 to be inserted through the open main shed 14 between the clamping zones W21 and W31 and simultaneously clamped by the auxiliary warp yarns 22. In other words, the auxiliary shed mechanism 25 closes the auxiliary shed 24 so as to clamp the weft yarn 100 by the auxiliary warp yarns 22 after the inserting device 90 has pulled the first weft yarn 100 through the first clamping zone W21 and while the inserting device 90 is still pulling the weft yarn 100 into the open main shed 14.

[0118] Preferably, the auxiliary shed mechanism 25 is configured to close the auxiliary shed 24 such that the weft yarn 100 is clamped in the clamping zone W21 while the weft yarn 100 is being pulled through the clamping zone W31.

[0119] When the front end limit of the weft yarn 100 reaches the clamping zone W31, the second auxiliary shed of the auxiliary warp yarn 32 opens. Then, the pulling S3 includes pulling the weft yarn 100 into the second auxiliary shed in the clamping zone W31. During or before the weft yarn 100 passes through the auxiliary shed of the auxiliary yarn 32, the step S9 of closing the auxiliary shed begins such that preferably the auxiliary shed of the auxiliary yarn 32 is closed once the front end limit of the weft yarn 100 and the rapier 91 exit from the clamping zone W31. This step S9 is shown in Figure 4 and Figure 5 the top. Thus, the closing of the auxiliary shed of the auxiliary warp yarn 32 is carried out before the closing of the main shed 14 is achieved or even before the closing of the main shed 14 begins and before the weft yarn 100 is fully pulled, in order to clamp the weft yarn 100 by the auxiliary warp yarn 32, i.e., to guide the translation of the weft yarn 100 at the clamping zone W31. The weft yarn 100 is clamped at both end limits and is precisely guided and positioned during pulling. The closing of the auxiliary shed in the clamping zone W21 may occur slightly before the rapier exits from the clamping zone such that once the gripper exits from the clamping zone, the auxiliary warp yarn clamps the weft yarn.

[0120] After the weft insertion S2 and preferably during the pulling S3, the step S8 of cutting the weft yarn 100 is carried out by the cutting device 93. The cutting is carried out such that the weft yarn 100 is of a given length, the given length being equal to the distance extending from the clamping zone W21 to the clamping zone W31, i.e., a length shorter than the width W11 of the main heddle. Thus, once pulled through the clamping zones W21 and W31, each end limit of the weft yarn 100 is positioned at one of the clamping zones W21 and W31, as Figure 5 shown. Preferably, the weft yarn 100 does not extend beyond the clamping zones W21 and W31 or only slightly extends beyond the clamping zones W21 and W31. Thus, an economical weft yarn is obtained. Nevertheless, the weft yarn 100 is still precisely and correctly positioned because its two end limits are clamped in the clamping zones W21 and W31.

[0121] Alternatively, before the pulling step, the weft yarn can be cut to a predetermined length and stored in a magazine.

[0122] Once the pulling S3 is completed and the weft yarn 100 is in the desired position along the weft axis Y90, i.e., the front end limit of the weft yarn 100 is in position P91, the insertion device 90 releases the weft yarn 100 in step S5, which preferably occurs after the main shed 14 starts to close in S6 but before the main shed 14 is fully closed. Preferably, the release is performed after the auxiliary shed of the auxiliary warp yarn 32 is fully closed and thus the weft yarn 100 is clamped in the area W31. For this purpose, the yarn clamp 92 is opened. After the release S5 and before the main shed 14 is fully closed, the insertion device 90 exits from the main heddle width W11, for example, by pulling the rapier 91 along the direction Y1 until the rapier 91 is completely outside the main heddle width W11.

[0123] The weft yarn 100 is beaten by the reed 95 after the insertion device 90 exits and before the main shed 14 is fully closed.

[0124] At the end of the first weft insertion, a clamping portion 112 is formed at the clamping zone W21, a clamping portion 113 is formed at the area W31, and a part of the main portion 111 is formed between the portions 112 and 113 for the layer L0.

[0125] Then, for successive layers such as Figure 5 the shown layer L1, and for the same weft insertion stack or successive weft insertion stacks, successive weft insertions according to the same pattern can be performed using another weft yarn to be inserted. If the layer to be formed includes two clamping portions, two sets of auxiliary heddles are successively opened and closed as described above, while the other auxiliary heddles are positioned away. If the layer should only include one clamping portion, such as Figure 5 the clamping portion 115 of the layer L2, then only one set of auxiliary heddles is successively opened and closed, while the other auxiliary heddles are positioned away. If the layer has no clamping portion, for example, there is no clamping portion for the layer L3, then all the auxiliary heddles are positioned away.

[0126] Specifically, in order to weave the layer L1 (the layer L1 has the same weft insertion stack as the layer L0 and is immediately after the layer L0), advantageously, the next weft insertion, which is called the "second weft insertion", is performed after the first weft insertion. The second weft insertion from θ = 360° to θ = 720° is shown in Figure 6 . In Figure 6 , the line G101 represents the weft yarn 100 being inserted into the shed. The second weft insertion includes steps similar to those performed during the first weft insertion and is outlined below.

[0127] This second weft insertion includes a step S10 of opening the main shed 14. The main shed 14 is opened in a pattern different from that during the first weft insertion, such that the weft yarn 101 of layer L1 can be inserted into the same weft insertion stack below the weft yarn 100. More precisely, the main shed 14 is opened below the weft yarn 100. Thus, in the main part 111 of the fabric 1, the weft yarns 100 and 101 are separated by the main warp yarns 12 that define the layers L0 and L1.

[0128] Step S10 further includes opening auxiliary sheds of the auxiliary warp yarns 22 and 32 by means of the auxiliary heddles 21 and 31.

[0129] The second weft insertion includes a step S11, in which, after the start of step S10 and after the insertion device 90 has translated through the shed, the insertion device 90 picks up the second weft yarn 101 at the weft insertion position P94; and the second weft insertion further includes a step S12, in which the insertion device 90 draws the weft yarn 101 from the weft insertion position P94 into the main shed and into two re-opened auxiliary sheds of the auxiliary warp yarns 22 and 32. In step S13, after the weft yarn 101 has passed through the clamping zone W21 and while the weft yarn 101 is still being drawn, preferably before the weft yarn 101 reaches the second clamping zone W31, the auxiliary shed of the auxiliary warp yarn 22 is closed by the auxiliary heddle 21. At this time, the main shed remains open. Alternatively, the main shed may start to close, but such that the main shed remains partially open. In step S13’, after the weft yarn 101 has passed through the clamping zone W31, the auxiliary shed of the auxiliary warp yarn 32 is closed by the auxiliary heddle 31. At this time, the main shed remains open. Alternatively, the main shed may start to close, but such that the main shed remains partially open. The main shed starts to close in step S15, preferably after the two auxiliary sheds are completely closed, and is completely closed at θ = 720°. Before the main shed is closed and after the auxiliary sheds are closed, the second weft insertion includes a step S14, in which, when the weft yarn 101 reaches a given position along the axis Y90, the insertion device 90 releases the second weft yarn 101. After the weft yarn 101 is inserted, the weft yarn 101 is beaten by the reed 95 to be brought to the fabric strip 3 in the same weft insertion stack as the weft yarn 100.

[0130] In the example shown, the differences between the second weft insertion and the first weft insertion are as follows, in order to achieve: the first extreme ends of the weft yarns 100 and 101 are clamped in the clamping part 112, and the second extreme ends of the weft yarns 100 and 101 are clamped in the clamping part 113 of the fabric 1. As described below, their differences from each other are that the auxiliary sheds do not cross at the end of the first weft insertion, while they cross at the end of the second weft insertion.

[0131] In step S10, the auxiliary shed of the warp threads 22 and 32 is opened so that any auxiliary warp threads that cross around the weft thread 100 during the first weft insertion no longer cross, thereby temporarily disengaging the weft thread 100 from the auxiliary warp threads that bind it in the first layer. In other words, as Figure 6 shown, from the first weft insertion to the second weft insertion, the main auxiliary warp threads and the sub-auxiliary warp threads do not invert. However, preferably, the weft thread 100 is woven into the fabric 1 through the main warp threads 12 of layer L0 during the entire second weft insertion, and at least some of the main warp threads 12 that cross around the weft thread 100 during the first weft insertion still remain crossed during the second weft insertion. After inserting the weft thread 101, the reed 95 beats the weft thread 101 against the weft thread 100. Therefore, in the clamping portions 112 and 113, no auxiliary warp threads separate the weft threads 100 and 101, and the weft threads 100 and 101 are stacked together in the Figure 5 same weft insertion stack as shown. Therefore, the same clamping portions 112 and 113 are used to clamp the extreme ends of two weft threads of the same weft insertion stack and different layers. This is possible if the relevant extreme ends of the weft threads 100 and 101 are located in the same clamping zone, such as clamping zone W21.

[0132] Specifically, in order to weave Figure 5 layer L3 in the cross-section of (the first weft thread 100 and the second weft thread 101 with the superimposition of layers L0 and L1 can be seen in the cross-section of Figure 5 ), another weft insertion is performed after the above-mentioned first weft insertion and second weft insertion, which is called "intermediate weft insertion".

[0133] In step S16, this intermediate weft insertion includes opening the main shed 14 through the main heddles 11 moved by the main shedding mechanism 15. This opening is carried out in such a way that the woven weft thread 100 is located above the newly opened main shed 14. For this purpose, the main shed 14 opened during the intermediate weft insertion has a different shape from the shape achieved for the same weft insertion stack during the previous weft insertions (including the first weft insertion and the second weft insertion). For example, all the main warp threads 12 that hold the weft thread 101 in layer L1 are moved upward through the main heddles 11 so that the main shed 14 is opened below these main warp threads 12 without spreading the weft threads 100 and 101. During the intermediate weft insertion, in step S20, the main heddles 11 moved by the main shedding mechanism 15 close the main shed 14 so that at the end of the intermediate weft insertion, the main shed is completely closed.

[0134] Since layer L3 does not require any clamping parts, all auxiliary shed are closed during intermediate weft insertion. In particular, since layer L3 is arranged below layer L0 and / or L1 related to auxiliary heddles 21 and 31, and layer L3 is not related to these auxiliary heddles, all these auxiliary heddles are away from the weft axis Y90, that is, kept above the weft axis Y90. In particular, since layer L3 is arranged above layer L7 related to auxiliary heddles 41, and layer L3 is not related to these auxiliary heddles 41, all these auxiliary heddles are away from the weft axis Y90, that is, kept below the weft axis Y90. More generally, during intermediate weft insertion, or during successive intermediate weft insertions, all auxiliary heddles dedicated to the layers below layer L7 are kept below the weft axis Y90.

[0135] Step S17 is performed by the insertion device 90. Step S17 includes: after the main shed 14 starts to open, picking up the weft yarn 102 called "intermediate weft" at the weft insertion position P94. In a further step S18, the intermediate weft 102 is pulled by the insertion device 90 along the weft axis Y90 from the weft insertion position P94 into the opened main shed 14. The pulling is performed until the front extreme end of the weft yarn 102 reaches the opposite end of the main lease wire width W11. At a certain point, the weft yarn 102 is cut so that the weft yarn 102 has a length equal to the main lease wire width W11. When the weft yarn 102 reaches the desired position along the weft axis Y90, the insertion device 90 releases the weft yarn 102 in step S19. After the insertion device 90 withdraws, the weft yarn 102 is beaten before the main shed 14 is completely closed.

[0136] At the end of intermediate weft insertion, the weft yarns 100, 101 and 102 are stacked in the same weft insertion stack (as Figure 1 shown), and are located at different layers (layers L0, L1 and L3 respectively) of the fabric 1. In layer L3, at this weft insertion stack, no clamping part is formed, and the main part 111 occupies the entire lease wire width W11.

[0137] An intermediate weft insertion similar to the intermediate weft insertion disclosed above can be implemented to weave layers according to the same pattern, wherein, in the same weft insertion stack, the intermediate weft will be stacked above the weft yarn 100 instead of below the weft yarn 100. In this case, during intermediate weft insertion, in step S16, the main shed 14 is opened so that the weft yarn 100 is located below the main shed 14 instead of above the main shed 14.

[0138] After the first weft insertion for layer L0 and the intermediate weft insertion for layer L3, a third weft insertion can be performed to form layer L7 in the same weft insertion stack by weaving the weft yarn 103.

[0139] The third weft insertion includes: in step S21, opening the main shed 14 through the main heddle 11 and opening two auxiliary sheds (these two auxiliary sheds include the auxiliary shed of the auxiliary warp 42) through the auxiliary heddle 41 to form the clamping portions 114 and 116. These main sheds and auxiliary sheds are opened in such a way that the intermediate weft 102 is located between the wefts 100 and 101 and the opened shed, so that once the weft 103 is woven, the weft 102 is located between the weft 101 and the weft 103, and the wefts 100, 101, 102 and 103 are stacked in the same weft insertion stack. In step S22, the insertion device 90 picks up the weft 103 at the weft insertion position P94. In step S23, the insertion device 90 pulls the weft 103 from the weft insertion position P94 into the main shed and the auxiliary sheds. During the pulling, each auxiliary shed closes after passing through the pulled weft 103 and before the main shed 14 closes. In particular, the auxiliary shed of the yarn 42 is closed by the third auxiliary heddle 41 moved by the auxiliary shed mechanism 45 to clamp the weft 103 in the clamping zone W41 by the auxiliary warp 42 after the insertion device 90 pulls the weft 103 through the clamping zone W41 and when the main shed 14 is still open. When the weft 103 reaches its desired position along the weft axis Y90, after the two auxiliary sheds are closed, the insertion device 90 releases the weft 103 in step S25. The closing of the first auxiliary shed and the second auxiliary shed corresponds to the passage of the rapier 91, in particular the passage of the gripper 92. The clamping operation for the auxiliary warp follows the position of the gripper 92 along the rapier axis. At the end of the weft insertion, the main shed 14 closes. In the finished fabric 1, as Figure 5 shown at the bottom, the wefts 100, 101, 102 and 103 are stacked in the same weft insertion stack, and the weft 102 is between the weft 100 and the weft 103.

[0140] In one embodiment, at one of these weft insertions, for example, at the intermediate weft insertion or any other weft insertion, the method may include opening the auxiliary shed 24 such that the inserted weft (e.g., the intermediate weft 102) of this weft insertion is inserted into the auxiliary shed 24 by the insertion device 90. In this case, the wefts 100 and 102 are woven into the same clamping portion of the fabric 1 and are or are not separated by the auxiliary warp 22. Figure 5 As shown in the layers L5 and L6, where the wefts of layer L5 and the wefts of layer L6 are woven into the clamping portion 116. In another embodiment, the method may include opening the auxiliary shed of the warp 42 such that the inserted intermediate weft 102 is inserted into the auxiliary shed of the warp 42 by the insertion device 90. In this case, the wefts of layer L7 and the weft 102 are woven into the same clamping portion of the fabric 1.

[0141] When the fabric 1 is completed or at least partially completed, the clamping portion can be cut away from the main portion 111 to easily obtain a near-net preform. Thus, the final structure and shape of the main portion 111 of the fabric 1 can be designed in a manner independent of the clamping portion used to assist in manufacturing the main portion 111.

[0142] Now turning to Figures 7 to 12 the embodiment of Figures 1 to 6 wherein the technical multi-layer fabric 201 is woven using a weaving loom similar to Figures 1 to 6 one of the embodiments of Figures 1 to 6 . The same terms are used to designate features similar to those in the embodiment of Figures 1 to 6 . In this particular embodiment, the loom 2 has a double rapier system instead of a single rapier system such as the insertion device 90, such that on both sides of the fabric 201, for the same weft insertion stack, two superimposed weft yarns can be inserted during each weft insertion. However, for Figures 7 to 12 the disclosed method can also be applied to the case where only one weft yarn is inserted during each weft insertion, similar to Figures 1 to 6 .

[0143] As Figure 7 shown, the fabric 201 includes woven weft and warp yarns. For the purpose of simplification, only some weft and warp yarns are shown. The fabric 201 includes a main portion 311 which includes woven main warp and weft yarns. The fabric 201 also includes a clamping portion 312 and a clamping portion 313. The clamping portion 312 includes woven weft and auxiliary warp yarn 322, and the clamping portion 313 includes woven weft and auxiliary warp yarn 332. The clamping portion 312 extends along the weft axis Y290 above the clamping zone W221 and is completely arranged within the main heddle width W211. The clamping portion 312 is superimposed on the clamping portion 313 to extend above the same clamping zone W221. As in Figures 1 to 6 the embodiment of Figures 1 to 6 , the main warp yarns are moved by the main heddles, while the auxiliary warp yarn 322 is moved by a first set of auxiliary heddles by means of a corresponding auxiliary shed mechanism, and the auxiliary warp yarn 332 is moved by a second set of auxiliary heddles by means of a corresponding auxiliary shed mechanism.

[0144] In Figures 7 to 12 this embodiment of Figures 7 to 12 , the weaving can include a first weft insertion similar to Figures 1 to 6 the first weft insertion of Figures 1 to 6 . During the first weft insertion, two weft yarns 301 are inserted in parallel by the insertion device, each weft yarn 301 being picked up by a corresponding rapier at a corresponding weft insertion position and being drawn into the opened shed of the warp yarns along the corresponding weft axis Y290. Preferably, the two axes Y290 are arranged in the same plane parallel to the directions Z1 and Y1.

[0145] For the warp threads, during the first weft insertion, two superimposed main shed openings 314 of the main warp threads are opened by the main heddles of the loom. Each main shed opening 314 is dedicated to inserting one inserted weft thread 301. Accordingly, each main shed opening 314 is opened around one of the corresponding weft thread axes Y290. The shed openings 314 are only partially shown in Figure 6 ; in particular, the main warp threads of the shed openings 314 between the axes Y290 are not shown. During the first weft insertion, two superimposed auxiliary shed openings of the auxiliary warp threads are also opened by the corresponding auxiliary heddle groups. Specifically, the auxiliary shed opening 324 of the auxiliary warp thread 322 is opened around one of the axes Y290 by a group of auxiliary heddles arranged along the clamping zone W221, and the auxiliary shed opening 334 of the auxiliary warp thread 332 is opened around the other of the axes Y290 by another group of auxiliary heddles arranged along the clamping zone W221. The main warp threads related to the layers between the layers of the inserted weft threads 301 are positioned away from the shed openings 314, 324, and 334, between said shed openings, for example, positioned at an intermediate position along the vertical axis, at which intermediate position, if the main warp threads are in the same stack, the main warp threads do not interfere with the said shed openings, such that the main warp threads are not part of the clamped portion of the clamping zone W211. Advantageously, the clamped portion is not combined with the main fabric and can be easily cut and removed after weaving.

[0146] As Figure 7 shown, the inserting device pulls each weft thread 301 through its corresponding auxiliary shed opening 324 or 334 and through its corresponding main shed opening 314.

[0147] As Figure 8 shown, once the weft thread 301 passes through the clamping zone W221, the auxiliary shed openings 324 and 334 are closed by the corresponding auxiliary heddles before the main shed opening 314 is closed, so that the weft thread 301 is clamped. One weft thread 301 is clamped by the auxiliary warp thread 322 by closing the shed opening 324, while the other weft thread 301 is clamped by the auxiliary warp thread 332 by closing the shed opening 334. Once the weft thread 301 is in its final predetermined position along the weft thread axis Y290, the weft thread 301 is released by the inserting device. After the inserting device withdraws, the main shed opening 314 is closed, and the weft thread 301 is beaten against the fabric strip of the fabric 201. The first weft insertion is achieved.

[0148] Figures 9 to 11 Relates to a second weft insertion performed after the first weft insertion shown in Figure 7 and Figure 8 ; preferably, the second weft insertion is performed immediately after the first weft insertion, without any weft insertion between the first weft insertion and the second weft insertion.

[0149] During the second weft insertion, two additional weft yarns 302 are inserted in parallel by the insertion device. Each weft yarn 302 is picked up by two respective rapier bars at two respective weft insertion positions and is drawn along two respective weft axes Y290 into the open shed of the warp yarns.

[0150] For the warp yarns, during the second weft insertion, the method includes opening the shed around the weft axis Y290, including opening the superimposed main sheds 314 of the main warp yarns, each main shed 314 being opened separately around the axis Y290 for inserting a respective weft yarn 302. Opening the shed also includes opening the superimposed auxiliary sheds 324 and 334 separately in the clamping zone W221 for inserting two weft yarns 302. During this second weft insertion, the auxiliary shed 324 is opened according to the following pattern: any auxiliary warp yarns 322 that cross around the upper weft yarn 301 are made to stop crossing, so as to release the extreme end of the weft yarn 301 located at the fabric strip, which extreme end is clamped by closing the auxiliary shed in the clamping zone W221. Similarly, the auxiliary shed 334 is opened according to the following pattern: any auxiliary warp yarns 332 that cross around the lower weft yarn 301 are made to stop crossing, so as to release the extreme end of the lower weft yarn 301 that is clamped by closing the auxiliary shed. Preferably, the weft yarn 301 is held attached to the fabric strip by at least some main warp yarns (not shown), and the main warp yarns remain crossed around the weft yarn 301 at the fabric strip. For example, this can be achieved if the closing of the main shed 314 during the first weft insertion crosses the main warp yarns around the weft yarn 301, and if the pattern of the main shed 314 during the second weft insertion is different from that during the first weft insertion. In other words, this can be achieved when some main warp yarns change their vertical positions relative to the weft axis between the first weft insertion and the subsequent second weft insertion.

[0151] As Figure 9 shown, the insertion device draws each weft yarn 302 through its respective auxiliary shed 324 or 334 and through its respective main shed 314.

[0152] As Figure 10 shown, once the weft yarn 302 has passed through the clamping zone W221, the auxiliary sheds 324 and 334 are closed by the respective auxiliary heddles before the main shed 314 is closed, so that the weft yarns 302 are clamped by the auxiliary warp yarns 322 and the auxiliary warp yarns 332 respectively. Since the auxiliary warp yarns 322 do not cross at the start of the second weft insertion, the upper weft yarns 301 and 302 remain together without being separated by any auxiliary warp yarns. Similarly, since the auxiliary warp yarns 332 do not cross at the start of the second weft insertion, the lower weft yarns 301 and 302 remain together without being separated by any auxiliary warp yarns. The upper weft yarns 301 and 302 are woven or joined together through the clamping portion in the same open shed in the final fabric. The lower weft yarns 301 and 302 are woven or joined together through the clamping portion in the same open shed in the final fabric.

[0153] Once the weft yarn 302 is drawn along the weft axis Y290 to its final predetermined position, the weft yarn 302 is released by the inserting device. After the inserting device withdraws and the main shed 314 closes, the weft yarn 302 is beaten against the fabric strip of the fabric 201. As Figure 11 and Figure 12 shown, the upper weft yarns 301 and 302 are stacked together without being separated by any auxiliary warp yarns, and are only tightened by the auxiliary warp yarns 322 that cross around the upper weft yarns 301 and 302. Similarly, the lower weft yarns 301 and 302 are stacked together without being separated by any auxiliary warp yarns, and are only tightened by the auxiliary warp yarns 332 that cross around the lower weft yarns 301 and 302. According to the weaving of the main part of the fabric, the weft yarns 301 and 302 can be integrated into a single weft insertion stack because the weft yarns 301 and 302 are not separated by any auxiliary warp yarns. In some cases, this can prevent the clamped part of the fabric from being too long or too short compared to the main part in the direction parallel to the direction X1, and generate internal stress in the fabric, which will increase the risk of some selvedge parts of the fabric being torn.

[0154] In Figures 7 to 12 the embodiment, two weft yarns are inserted during each weft insertion. However, similar steps can be applied to Figures 1 to 6 the case where only one weft yarn is inserted during each weft insertion, or the case where more than two weft yarns are inserted simultaneously during each weft insertion.

[0155] Figure 13 Another embodiment of the fabric 401 is shown, which includes two clamping parts 512 and 513 distributed at the corresponding layers L1 and L2 of the fabric 401. The clamping parts 512 and 513 respectively include the woven-in auxiliary warp yarns 522 and 532. For each of the layers L1 and L2, a group of four weft yarns 501, 502, 503, 504 are stacked together in the clamping parts 512 and 513 without being separated by any auxiliary warp yarns. This is achieved by repeating the sequence of steps disclosed in Figures 7 to 12 the embodiment until four weft yarns such as the weft yarns 301 and 302 are stacked. Such a fabric can be obtained on a weaving loom with a single or two superimposed or more inserting devices. Advantageously, a thick weft yarn or an elastic weft yarn provided by a Chenille bobbin can be clamped in the clamping part. Advantageously, during the weaving of the fabric 401 in a manner parallel to the direction X1, the take-up of the clamping parts 512 and 513 is approximately the same as the take-up of the fabric 401 into the fabric beam.

[0156] The fabric 401 also includes a main part 511 extending at the layers L1 and L2. The clamping parts 512 and 513 are shown offset with respect to the main part 511 such that the main part 511 is fully visible.

[0157] For each of the layers L1 and L2, the weft yarns 501, 502, 503, and 504 extend into the main portion 511 and interlace with the main warp yarns 412 of the main portion 511. In addition, the main portion 511 includes binding warp yarns 412A that are woven together with the weft yarn 502 of layer L1 and the weft yarn 501 of layer L2 to bind the two layers L1 and L2 together.

[0158] In one embodiment, one side of the weft yarn of the fabric is locally positioned along the weft axis during each weft insertion such that a first weft limit end of the weft yarn is locally positioned along the weft axis, but a second weft limit end of the weft yarn is clamped by an additional warp yarn driven by a selvedge device located on the heddle side opposite the weft insertion side, or by an additional warp yarn driven by a selvedge device located on the heddle side at the weft insertion side.

[0159] The loom may include a selvedge device for clamping the local weft yarn before closing the main shed. The selvedge device may have the same structure as the auxiliary shed mechanism and the associated set of auxiliary heddles disclosed above. Additionally, the selvedge device may be of a conventional structure, i.e., mechanically driven by the weaving loom and disposed on the heddle side to clamp the weft yarn before closing the main shed.

[0160] The loom may be equipped with multiple and / or arranged auxiliary shed mechanisms and sets of auxiliary heddles to obtain different numbers and / or arrangements of clamping zones along the weft axis.

[0161] In one embodiment, a clamping portion of the multi-layer fabric may conform to the contour of the multi-layer fabric warpwise such that multiple layers of the fabric are woven by auxiliary warp yarns and the multi-layer fabric has a narrowed contour in a plane parallel to directions Y1 and Z1.

[0162] When technically feasible, any feature disclosed above in the context of a particular embodiment may be implemented in other disclosed embodiments.

Claims

1. A weaving loom for weaving a multi-layer fabric (1; 201; 401) including warp yarns and weft yarns, wherein the weft yarns have different lengths, and wherein the weaving loom (2) comprises: · An inserting device (90) configured to: ◆ Pick up a weft yarn at a weft insertion position (P94) along a weft axis (Y90) of the weaving loom (2), ◆ Pull the weft yarn from the weft insertion position (P94) along the weft axis (Y90) into a shed of the warp yarns, and ◆ Release the weft yarn at a given position (P91) along the weft axis (Y90); · A main harness (11) configured to guide main warp yarns (12) and define a main heddle width (W11) along the weft axis (Y90); and ● A main shed mechanism (15) of the jacquard type configured to move the main harness (11) along a vertical path; It is characterized in that: ● The weaving loom (2) comprises: ◆ A set of first auxiliary harnesses (21) configured to guide first auxiliary warp yarns (22) and define a first clamping zone (W21) along the weft axis (Y90), the first clamping zone (W21) being arranged within the main heddle width (W11); ◆ A first auxiliary shed mechanism (25) configured to move the first auxiliary harnesses (21); and · The weaving loom (2) is configured, during a first weft insertion: ◆ Open a main shed (14) of the main warp yarns (12) by the main harness (11) moved by the main shed mechanism (15), and open a first auxiliary shed (24) of the first auxiliary warp yarns (22) by the first auxiliary harnesses (21) moved by the first auxiliary shed mechanism (25) to insert a first weft yarn (100) through the inserting device (90); and ◆ Close the first auxiliary shed (24) by the first auxiliary harnesses (21) moved by the first auxiliary shed mechanism (25) to clamp the first weft yarn (100) in the first clamping zone (W21) by the first auxiliary warp yarns (22) after the inserting device (90) has pulled the first weft yarn (100) through the first clamping zone (W21) and while the main shed (14) remains open.

2. The knitting loom (2) according to claim 1, wherein, The first auxiliary shed mechanism (25) is configured to close the first auxiliary shed (24) to clamp the first weft yarn (100) while the inserting device (90) is still pulling the first weft yarn (100) into the main shed (14).

3. The weaving loom (2) according to claim 1 or 2, wherein: ● The weaving loom (2) comprises: ◆ A set of second auxiliary harnesses (31) configured to guide second auxiliary warp yarns (32) and define a second clamping zone (W31) along the weft axis (Y90), the second clamping zone (W31) being arranged within the main heddle width (W11); ◆ A second auxiliary shed mechanism (35) configured to move the second auxiliary harnesses (31); ● The first clamping zone (W21) is arranged between the weft insertion position (P94) and the second clamping zone (W31); and ● The weaving loom (2) is configured to, during the first weft insertion: ◆ Open a second auxiliary shed of the second auxiliary warp threads (32) by the second auxiliary heddle (31) moved by the second auxiliary shed mechanism (35) to insert the first weft yarn (100) through the insertion device (90); and ◆ Close the second auxiliary shed by the second auxiliary heddle (31) moved by the second auxiliary shed mechanism (35) to clamp the first weft yarn (100) in the second clamping zone (W31) by the second auxiliary warp threads (32) after the insertion device (90) has pulled the first weft yarn (100) through the second clamping zone (W31) and while the main shed (14) is still open.

4. The braiding loom (2) according to claim 3, wherein, The first auxiliary shed mechanism (25) is configured to close the first auxiliary shed (24) to clamp the first weft yarn (100) in the first clamping zone (W21) when the insertion device (90) pulls the first weft yarn (100) into the second clamping zone (W31).

5. The knitting loom (2) according to claim 1 or 2, wherein, The weaving loom (2) includes beams (85, 86) that support the first auxiliary shed mechanism (25), and the position of the first auxiliary shed mechanism (25) can be adjusted along the beams (85, 86) in a manner parallel to the weft axis (Y90).

6. The braiding loom (2) according to claim 1 or 2, wherein, The first auxiliary shed mechanism (25) includes: ● A main actuator (81) for moving the main auxiliary heddles in the first auxiliary heddles (21) according to a main reciprocating motion; and ● A sub - actuator (82) for moving the sub - auxiliary heddles in the first auxiliary heddles (21) according to a sub - reciprocating motion opposite to the main reciprocating motion to have an adjustable intersection point.

7. The weaving loom (2) according to claim 1 or 2, wherein: ● The first auxiliary shed mechanism (25) includes at least one actuator (81, 82), and the actuator includes a stator (83) and a pulley (84) that is rotatably driven relative to the stator (83); and · Each pulley (84) is configured to move at least one of the first auxiliary heddles (21).

8. The knitting loom (2) according to claim 7, wherein, Each pulley is configured to move three first auxiliary heddles (21).

9. The braiding loom (2) according to claim 1 or 2, wherein, The main shed mechanism (15) includes: ● Selectable hooks, each selectable hook driving at least one of the main heddles (11); · Blades for driving the selectable hooks between an upward position and a downward position; and · A main shaft for driving the blades.

10. A method for weaving a multi-layer fabric (1; 201; 401) The method, wherein the weft yarns have different lengths, and the weaving loom (2) includes: · An insertion device (90), configured to: ◆ Pick up a weft yarn at the weft insertion position (P94) along the weft axis (Y90) of the weaving loom (2), ◆ Pull the weft yarn from the weft insertion position (P94) along the weft axis (Y90) into the shed of the warp threads, and ◆Release the weft yarn at a given position (P91) along the weft axis (Y90); ●A main harness (11), configured to guide the main warp yarns (12) and define a main heddle width (W11) along the weft axis (Y90); and ●A main shed mechanism (15) of the jacquard type, configured to vertically move the main harness (11) along a vertical path; It is characterized in that: ●The weaving loom (2) includes: ◆A set of first auxiliary harnesses (21), configured to guide the first auxiliary warp yarns (22) and define a first clamping zone (W21) along the weft axis (Y90), the first clamping zone (W21) being arranged within the main heddle width (W11); and ◆A first auxiliary shed mechanism (25), configured to move the first auxiliary harnesses (21); and ·The method includes, during the first weft insertion: ◆(S1) Open the main shed (14) of the main warp yarns (12) by the main harness (11) moved by the main shed mechanism (15), and open the first auxiliary shed (24) of the auxiliary warp yarns by the first auxiliary harness (21) moved by the first auxiliary shed mechanism (25); ◆(S2) Pick up the first weft yarn (100) at the weft insertion position (P94) by the insertion device (90); ◆(S3) Pull the first weft yarn (100) from the weft insertion position (P94) into the main shed (14) and into the first auxiliary shed (24) by the insertion device (90); ◆(S4) Close the first auxiliary shed (24) by the first auxiliary harness (21) moved by the first auxiliary shed mechanism (25) to clamp the first weft yarn (100) in the first clamping zone (W21) by the first auxiliary warp yarns (22) after the insertion device (90) has pulled the first weft yarn (100) through the first clamping zone (W21) and while the main shed (14) is still open; ◆(S5) Release the first weft yarn (100) by the insertion device (90); and ◆(S6) Close the main shed (14) by the main harness (11).

11. The method according to claim 10, wherein, During the first weft insertion, the first auxiliary shed mechanism (25) closes the first auxiliary shed (24) to: ·Clamp the first weft yarn (100) after the insertion device (90) has pulled the first weft yarn (100) through the first clamping zone (W21); and ·Clamp the first weft yarn (100) while the insertion device (90) is still pulling the first weft yarn (100) into the main shed (14).

12. The method according to claim 10 or 11, wherein: ●The weaving loom (2) includes: ◆A set of second auxiliary harnesses (31), configured to guide the second auxiliary warp yarns (32) and define a second clamping zone (W31) along the weft axis (Y90), the second clamping zone (W31) being arranged within the main heddle width (W11); ◆The second auxiliary shed mechanism (35) is configured to move the second auxiliary heddle (31); · The first clamping zone (W21) is arranged between the weft insertion position (P94) and the second clamping zone (W31); and · The method includes, during the first weft insertion: ◆(S7) opening a second auxiliary shed by the second auxiliary heddle (31) moved by the second auxiliary shed mechanism (35), wherein pulling the first weft yarn (100) by the insertion device (90) includes pulling the first weft yarn (100) into the second auxiliary shed; and ◆(S9) closing the second auxiliary shed by the second auxiliary heddle (31) moved by the second auxiliary shed mechanism (35) to clamp the first weft yarn (100) in the second clamping zone (W31) by the second auxiliary warp yarn (32) when the main shed (14) is still open after the insertion device (90) pulls the first weft yarn (100) into the second clamping zone (W31) and before the insertion device (90) releases the first weft yarn (100).

13. The method according to claim 12, wherein, The method further includes, during the first weft insertion: · (S8) after picking up the first weft yarn (100), cutting the first weft yarn (100) along the weft axis (Y90) by a given length, the given length being equal to the distance from the first clamping zone (W21) to the second clamping zone (W31).

14. The method according to claim 10 or 11, wherein The method further includes, during a second weft insertion performed after the first weft insertion: · (S10) opening the main shed (14) by the main heddle (11) moved by the main shed mechanism (15) and opening the first auxiliary shed (24) by the first auxiliary heddle (21) moved by the first auxiliary shed mechanism (25); ● (S11) picking up a second weft yarn (101) at the weft insertion position (P94) by the insertion device (90); · (S12) pulling the second weft yarn (101) from the weft insertion position (P94) into the main shed (14) and into the first auxiliary shed (24) by the insertion device (90); ● (S13) closing the first auxiliary shed (24) by the first auxiliary heddle (21) moved by the first auxiliary shed mechanism (25) to clamp the second weft yarn (101) in the first clamping zone (W21) by the first auxiliary warp yarn (22) when the main shed (14) is still open after the insertion device (90) pulls the second weft yarn (101) past the first clamping zone (W21); ● (S14) releasing the second weft yarn (101) by the insertion device (90); and · (S15) closing the main shed (14) by the main heddle (11); Opening the first auxiliary shed (24) during the second weft insertion includes: causing any first auxiliary warp threads (22) that cross around the first weft thread (100) during the first weft insertion to stop crossing, such that at the end of the second weft insertion, the first weft thread (100) and the second weft thread (101) are stacked together without being separated by any first auxiliary warp threads (22).

15. The method according to claim 10 or 11, wherein: · The weaving loom (2) includes: ◆ A set of third auxiliary heddles (41), configured to guide third auxiliary warp threads (42) and define a third clamping zone (W41) along the weft thread axis (Y90), the third clamping zone (W41) being arranged within the main harness width (W11); ◆ A third auxiliary shed mechanism (45), configured to move the third auxiliary heddles (41); · The method further includes, during an intermediate weft insertion performed after the first weft insertion: ◆ (S16) Opening the main shed (14) by the main harnesses (11) moved by the main shed mechanism (15), such that the first weft thread (100) is located above or below the main shed (14); ◆ (S17) Picking up an intermediate weft thread (102) at the weft insertion position (P94) by the insertion device (90); ◆ (S18) Pulling the intermediate weft thread (102) from the weft insertion position (P94) into the main shed (14) by the insertion device (90); ◆ (S19) Releasing the intermediate weft thread (102) by the insertion device (90); and ◆ (S20) Closing the main shed (14) by the main harnesses (11) moved by the main shed mechanism (15), such that the first weft thread (100) and the intermediate weft thread (102) are stacked in the same weft insertion stack; · The method further includes, during a third weft insertion performed after the intermediate weft insertion: ◆ (S21) Opening the main shed (14) by the main harnesses (11) moved by the main shed mechanism (15), and opening a third auxiliary shed of the third auxiliary warp threads (42) by the third auxiliary heddles (41) moved by the third auxiliary shed mechanism (45), such that the intermediate weft thread (102) is located between the first weft thread (100) and the main shed (14); ◆ (S22) Picking up a third weft thread (103) at the weft insertion position (P94) by the insertion device (90); ◆ (S23) Pulling the third weft thread (103) from the weft insertion position (P94) into the main shed (14) and into the third auxiliary shed by the insertion device (90); ◆(S24) Close the third auxiliary shed by the third auxiliary heddle (41) moved by the third auxiliary shed mechanism (45), so that after the inserting device (90) pulls the third weft yarn (103) through the third clamping zone (W41) and the main shed (14) is still open, clamp the third weft yarn (103) in the third clamping zone (W41) by the third auxiliary warp yarn (42); ◆(S25) Release the third weft yarn (103) by the inserting device (90); and ◆(S26) Close the main shed (14) by the main heddle (11), so that the first weft yarn (100), the intermediate weft yarn (102) and the third weft yarn (103) are stacked in the same weft insertion stack, and the intermediate weft yarn (102) is located between the first weft yarn (100) and the third weft yarn (103).

16. The method according to claim 15, wherein, The method includes during the intermediate weft insertion: ● Keep the first auxiliary heddle (21) above the weft axis (Y90); and · Keep the third auxiliary heddle (41) below the weft axis (Y90).

17. The method according to claim 15, wherein, The method includes during the intermediate weft insertion: ● Open the first auxiliary shed (24) by the first auxiliary heddle (21) moved by the first auxiliary shed mechanism (25), so that the intermediate weft yarn (102) is inserted into the first auxiliary shed (24) by the inserting device (90); and / or ● Open the third auxiliary shed by the third auxiliary heddle (41) moved by the third auxiliary shed mechanism (45), so that the intermediate weft yarn (102) is inserted into the third auxiliary shed by the inserting device (90).

18. The method according to claim 10 or 11, wherein The method includes during the first weft insertion: increasing the tension of the first auxiliary warp yarn (22) and simultaneously closing the first auxiliary shed (24) to clamp the first weft yarn (100) by the tensioned first auxiliary warp yarn (22).

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