Loom

Abstract

The invention relates to special structures, which may be generally descrd as three-dimensional fabrics, that is to say fabrics which have substantial measurements in three dimensions as compared with conventional fabrics having substantial measurements in only two dimensions. The structures have special application aa reinforcing materials in composites such as resin-carbon fibre composites, and consist of ground warps in a matrix of binder warps and wefts, which three sets of components extend in three directions substantially at right angles to each other and lying substantially straight in the body of the structures. The invention also includes a method of producing such structures involving progressing the ground warps longitudinally in three dimensional array and inserting the binder warps and wefts appropriately. The invention also includes a machine for carrying out this method, constructed generally along the lines of a loom, and having the necessary instrumentalities for manipulating the three sets of components in appropriate manner.

Parent Case Text

This is a division, of application Ser. No. 92,982 filed Nov. 27, 1970.

Description

This invention concerns apparatus for producing structures which have component threads extending in three directions all substantially at right angles to each other.

The main object of the present invention is to provide apparatus for producing fabrics which are suitable as reinforcing structures in composite materials (for example a resin-carbon fibre composite) where high tensile strength is required in three such directions producing such fabrics.

According to the present invention there is provided a weaving machine adapted to produce a structure having a three-dimensional array of ground warps, a plurality of binder warps and a plurality of wefts, the machine comprising in combination, means for holding said ground warps in said three-dimensional array during commencement of weaving, ground warp layer separating means, weft-insertion means adapted to lay straight spaced wefts between separated ground warp layers in a direction which is generally and substantially at right angles to the longitudinal extent of said ground warps and across the width of said array, guide means adapted to lay-in said binder warps with said ground warps and said wefts in a direction generally and substantially at right angles to the longitudinal direction of said ground warps and through the depth of said array, and means for linearly progressing said structure as it is woven.

In the structure to be produced it is preferred that each ground warp is a continuous thread extending longitudinally of the structure, the ground warps being disposed in horizontal rows and vertical columns. It is also desirable that each binder warp is a continuous thread lying between adjacent pairs of vertical columns of ground warps, extending alternately upwardly and downwardly vertically through the depth of the structure and embracing between each pair of successive vertical portions thereof a complete vertical series of wefts; and that the wefts are formed from a continuous thread extending alternately in one direction and the other across the width of the structure alternately throughout the depth of the structure from top to bottom and from bottom to top and embracing between each pair of successive horizontal portions thereof a complete horizontal row of ground warps.

The use of the word "three-dimensional" in connection with the structures produced by the present invention means that they have substantial measurements in three dimensions, as compared with, say, conventional textile fabrics having substantial measurements in two dimensions only.

The invention will now be described further, by way of example only, with reference to the accompanying drawings, in which,

Fig. 1 is a perspective view of a short length of fabric structure which is to be produced by apparatus according to the invention, the thread spacings being somewhat exaggerated in the interests of clarity;

Fig. 2 is a side view, to a reduced scale, of the fabric structure of FIG. 1;

Fig. 3 is a plan view to the same scale as FIG. 2 of the fabric structure of FIG. 1;

Fig. 4 is a diagrammatic side view of a weaving machine according to the invention, for producing the fabric of FIGS. 1, 2 and 3;

Fig. 5 is an elevation of the reed of the machine of FIG. 3, showing the thread distribution therein;

Fig. 6 is a diagrammatic side view of part of the weaving machine of FIG. 4 showing the arrangement for progressing binder warps;

Figs. 7 and 8 are, respectively, diagrammatic side and perspective views of part of the weaving machine of FIG. 4 showing an assembly of separating bars and its manner of operation;

Fig. 9 is a diagrammatic end view of part of the weaving machine of FIG. 4 showing a heald frame and its manner of operation;

Fig. 10 is a diagrammatic side view of part of the weaving machine of FIG. 4, showing the reed and its method of operation;

Fig. 11 is a diagrammatic perspective view of part of the weaving machine of FIG. 4 showing a take-up mechanism, and

Figs. 12 and 13 are, respectively, diagrammatic end and plan views of part of the weaving machine of FIG. 4 showing a weft insertion mechanism and its method of operation.

The fabric of FIG. 1 consists of three systems of parallel threads as follows:

1. The ground warp threads GW, running in the longitudinal horizontal direction (the x-direction).

2. The weft threads W, running in the transverse horizontal directions (the y-direction).

3. The binder warp threads BW, running in the vertical direction (the z-direction).

The arrangement of the three systems of threads is shown more clearly in FIGS. 2 and 3. This arrangement is such that the threads are firmly bound into the fabric at the upper and lower and the two side surfaces.

In order to achieve the arrangement shown in these figures, it is necesary that the total number of binder warp threads should be one less than the total number of vertical columns of ground warp threads so that at each side of the fabric there should be a vertical columns of ground warp threads.

Furthermore, it is necessary that the total number of weft threads in a vertical columns should be equal to the total number of ground warp threads in a vertical columns, and that alternate vertical columns of weft threads should have their uppermost weft thread above and below the uppermost horizontal row of ground warp threads respectively, and their lowermost weft thread below and above the lowermost horizontal row of ground warp threads respectively.

The laying-in of the binder warp must be synchronised with the weft insertion so that at each reversal of direction of the binder warps they embrace a weft which in turn lies above or below, as the case may be, a horizontal row of ground warps.

A weaving machine suitable for producing the type of fabric described above is shown in FIG. 4. A warp beam BG carries the ground warp threads, although for some fabrics it may be necessary to use several such beams. A warp beam BB carries the threads of the binder warp although for some fabrics it may be necessary to use a creel of yarn packages. Both warp beams are fitted with suitable braking devices (not shown) so that the warp threads are unwound under tension.

The ground warp threads GW pass over a roller RL and through two sets or columns of horizontal spacing or separating bars SBR (1 - 5) and SBL (1 - 5) arranged in pairs. They pass then between heald wires HW which are attached to a heald frame HF. The threads then pass through the reed RD which is capable of carrying out an oscillating beating-up motion as indicated by the arrows, by virtue of a mechanism (not shown in FIG. 4).

The horizontal bars SBR, SBL are designed to open a warp gap between adjacent horizontal rows or layers of ground warp threads to facilitate the insertion of weft W by a weft-insertion mechanism (not shown in FIG. 4). For each such horizontal row, two bars are required:-- One (SBR) which is under the appropriate row of threads and which serves to raise it, and one (SBL) above, which serves to lower it.

In order to facilitate the accommodation in depth of all these bars, the raising bars are slightly offset horizontally in the direction of the length of the in relation to the lowering bars.

The binder warp threads BW pass from the beam BB over a tension bar TB. This bar (as illustrated in FIG. 6) is capable of carrying out a vertical oscillating motion as indicated by the adjacent arrows and serves to keep the tension in the binder warp threads substantially constant as the heald frame HF carries out its vertical oscillating motion as indicated by the adjacent arrows. The binder warp threads pass through the eyes EY of the heald wires HW so that these threads are raised or lowered as the heald frame HF is raised or lowered. The binder warp threads also pass through the reed RD.

The number of dents per cm of the reed is equal to twice the number of vertical columns of ground warp threads per cm. FIG. 5 shows how the ground and binder warp threads respectively are drawn through the reed. There is always one binder warp thread in each alternate dent. In the remaining dents there are as many ground warp threads per dent as there are horizontal rows of such threads.

Before weaving commences, the ends of all ground and binder warp threads are drawn off the beams to a wire mesh WM at the front of the machine and are attached to the mesh by means of knots, adhesive tape or any other suitable means. A take-up mechanism (not shown in this figure) is provided to advance the fabric as it is produced. It has an advancing movement which is intermittent and takes place whenever a complete vertical row of weft threads has been inserted into the fabric. The rate at which the take-up mechanism advances the fabric determines the number of vertical rows of weft threads per cm fabric length. If, for instance, the fabric is advanced by 1 mm when one vertical row of weft threads has been inserted there will be 10 such rows per cm of fabric length.

Mechanism (not shown in FIG. 4) is also provided for carrying out the vertical movement of the heald frame HF and vertical movement of the individual bars SB.

For the commencement of weaving, the heald frame HF is in the lowered position. All the bars SB are also in the lowered position with the exception of SBR1 and SBL1 which are in the raised position thus forming a warp gap into which the weft W is inserted. (The mechanism for inserting the weft is not shown in FIG. 4). After the first weft thread W has been inserted, the second bars SBR2 and SBL2 are raised and join SBR1 and SBL1 in the raised position. The second weft thread is then inserted into the newly formed gap. This process is continued until the last weft thread (in the diagram the fifth weft thread) of the first vertical row of weft threads has been inserted. The reed RD now moves forward and carries out the beat-up of the whole first vertical row of weft threads. The heald frame HF is then raised to insert the vertical binder warps, the lowest bars SBR5 and SBL5 are lowered to form the gap for the next weft thread and the fabric moves forward. The next weft thread is now inserted and pair by pair all the bars are lowered and after each such lowering, the corresponding weft thread is inserted until the second vertical row of weft threads is complete. The second row is then beaten up by the reed and once again the heald frame HF is lowered to insert the vertical binder warps and the highest bars SBR1 and SBL1 are raised to form the gap for the next weft thread, and so on.

In order to prevent fraying of the fabric on its surfaces it is desirable but not essential that a shuttle method of weft insertion should be used. Since the fabric produced here is of considerably greater depth than fabrics produced on conventional looms, it is not practicable to have the conventional type of race board to support the shuttle. It is therefore convenient to have a means of propelling the shuttle which provides positive control and support for the shuttle during the whole of its journey across the fabric. Furthermore, with very thick fabrics, weft insertion takes place over a considerable range of heights, and therefore with such fabrics it is desirable to have a means of weft insertion which can insert the shuttle at different heights. A mechanism which meets these requirements is shown in FIGS. 12 and 13 and will be later described in more detail.

Reference will now be made to FIGS. 6 to 13 in which are shown details of certain parts of the weaving machine illustrated diagrammatically in FIG. 4.

FIG. 6 illustrates the manner in which the tension bar TB is enabled to carry out its vertical oscillating motion in order to keep the tension in the binder warp threads BW substantially constant as the heald frame HF oscillates vertically.

The tension bar TB is rotatably mounted at one end of a lever 10 which itself is pivotally supported about an intermediate point, the other end of the lever being connected to a low-modulus tension spring 12. The tension spring 12 has the effect of urging the tension bar into contact with the binder warps BW passing over the tension bar TB, irrespective of the vertical displacement of the heald frame HF through which the binder warps BW pass. FIG. 6 shows in full line the position of the heald frame HF, the binder warps BW, the tension bar TB and the lever 10 at the upper extremity of the movement of the heald frame HF, and in broken line their positions at the lower extremity of movement of the heald frame HF.

Referring to FIGS. 7 and 8, it will be seen that each pair of bars SBR, SBL form part of an independent rectangular framework 14 pivotally mounted about a common axis with the other frameworks. Thus in the present machine there are five such frameworks 14, all of which are shown in FIG. 7, but two only of which for the sake of clarity are shown in FIG. 8. The bars are disposed transversely of the respective frameworks to one side of the pivot axis, and the other end of each framework is connected by wires 16 at the other side of the pivot axis to the jacks of a conventional dobby, whereby the required movements of the bars are controlled. In FIG. 7 all five frameworks are shown in the lowermost position in full line, whilst the raised position of two only are shown in broken line. This type of construction is suitable where a small number of horizontal rows of ground warps is involved. For larger numbers a different mechanism less demanding in terms of space would be desirable.

FIG. 9 illustrates the mechanism for raising and lowering the heald frame HF. The heald frame HF itself is of conventional construction embodying the appropriate number of heald wires HW through the eyes of which the binder warps BW pass. The vertical oscillation of the heald frame HF in guides G is accomplished via a linkage motivated by a cam 18 driven through gearing at the appropriate speed by the prime mover of the weaving machine. The cam 18 rotates in the direction indicated by the adjacent arrow, and the linkage consists of a main link 20, the movement of which is controlled by a cam follower 22 carried thereby and running in a groove 24 in the cam 18, and two subsidiary sets of links 26, 28 connecting the main link 20 to the heald frame HF. Oscillatory movement of the main link 20 is indicated by the adjacent arrows and as will be obvious from the drawing this results in a vertical oscillatory movement of the heald frame HF, as indicated by the adjacent arrows, by virtue of the auxiliary links 26, 28.

FIG. 10 illustrates the mechanism by which the reed RD performs its beat-up function. The reed RD is mounted on one extremity of a lever 30 which is pivotally supported at its other extremity. The lever 30 is connected by a link 32 to a rotating crank 34 driven from the prime mover of the weaving machine through appropriate gearing so that the beat-up motion of the reed RD occurs each time a complete series of weft threads is laid in the fabric structure in a vertical plane.

The take-up mechanism is illustrated in FIG. 11. This mechanism is diposed between wire mesh WM and a fell control which is not illustrated, but which merely consists of a pair of adjustable horizontal restraining bars disposed above and below the fabric near the beat-up point. Basically the take-up mechanism consists of two pairs of rollers 36, 38. The first pair of rollers 36 are vertically disposed and rotatably mounted between two plates 40, the upper one only of which is shown for the sake of clarity. Each is mounted on a shaft 42 which is journalled in the two plates 40. The shaft of one roller may be disposed in any one pair of a series of alternative pairs of holes 44 in the plates 40, whilst the shaft of the other is mounted in slots 46 in the plates 40 and retained therein by means of a compression spring 48, the loading of which can be adjusted by means of a screw 50. In this way this pair of rollers 36 constrains the fabric F issuing from the weaving machine at each side thereof. The other pair of rollers 38 are mounted horizontally. Each is supported on a shaft 52, which is journalled in two side plates 54, the shaft 52 of the upper roller 38 being carried in slots 56 and retained therein by compression springs 58, the loading of which is adjustable by means of a screw 60, and the shaft 52 of the lower roller 38 being journalled in the appropriate pair of a series of alternative pairs of holes in the plates 54. These two rollers 38 constrain the top and bottom of the fabric F issuing from the weaving machine. All the rollers are driven in the directions indicated by the arrows thereon by the prime mover of the machine. Their motion is intermittent because the drive from the prime mover is transmitted in synchronism with the movement of the heald frame HF, so that the fabric F is progressed by the rollers in the intervals between the laying-in of the binder warps BW. The drive of the rollers is effected by means of shafts 62, 64 suitable bevel gearing 66, chain wheels 68 and chains 70.

FIGS. 12 and 13 illustrate the weft insertion mechanism. It consists basically of two rapiers RA, RB which can carry out a horizontal movement into and out of the warp gap as indicated by the adjacent arrows. The shuttle S is held at the end of one rapier by suitable prongs and springs, and when the ends of the two rapiers meet inside the warp gap the shuttle is passed from the rapier which has carried it into the gap, to the other rapier which carries it out of the gap as it is withdrawn. In addition to the drive for the horizontal movement of the rapiers, there is a vertical drive which serves to adjust the rapier height to correspond to the height at which any particular weft thread needs to be inserted. With this in view, the rapiers RA, RB are supported on arms 72 pivotally mounted at each end of a transverse bar 74 supported by a vertical lead screw 76. The appropriate movement of the arms 72 is effected by means of links 78 connected at one end to the respective arms 72 at an intermediate point thereof and at the other end to opposed crank pins on a gearwheel 80 driven by a gearwheel 82 on the end of a vertical shaft 84 having a keyway coupling with a hollow shaft 86 which is driven through suitable gearing from the machine's prime mover. The gearwheel 80 is mounted at the upper end of the lead screw 76, the threaded lower end of which is mounted in a nut 88, the rotation of which is controlled by a pinned plate 90 on which it is mounted. The pinned plate 90 is intermittently driven by a double pallet mechanism 92 which oscillates in a horizontal plane by virtue of two cams 94, 96 driven by the machine's prime mover and under the influence of springs 98, 100. Cam 96 rotates continuously to reciprocate the pallet and index the plate 90 so that the rapiers move vertically to enable weft insertion to take place at the various heights. Cam 98 rotates intermittently to adjust the position of the pallet mechanism so that the direction of movement of the plate 90 and thus of the rapier assembly is reversed as required.

The design of various parts of the machine depends to some extent on the dimensions, structure and shape of the fabric it is intended to produce. The general principles are as follows:

The width of the reed must be slightly in excess of the maximum width of the fabric.

The vertical clearance of the reed must be slightly in excess of the maximum thickness of the fabric.

The number of dents per cm of the reed must be twice the number of vertical columns of ground warp ends per cm of fabric width.

The height range over which weft insertion will take place must be equal to the maximum thickness of the fabric.

The number of warp beams required for the ground warp depends on the number and denier of the ground warp ends.

Whether the binder warp is supplied to the machine from a creel or from beams depends on the shape of the cross-section of the fabric. If the thickness of the fabric is uniform, beams can be used. If the thickness of the fabric varies along its width, a creel must be used. The number of beams or the size of the creel depends on the number and denier of the binder warp ends.

The number and denier of the ground and binder warp ends and the denier of the weft can be calculated from the yarn strength and from the strength required from the fabric in the x, y and z directions respectively. In these calculations, the basic structure of the fabric is determined by the following three independent variables:

Ny = no. of ground warp threads per cm per transverse row

= No. of binder warp threads per cm per transverse row

Nz = no. of ground warp threads per cm per vertical column

= No. of weft threads per cm per vertical column

Nx = no. of binder warp threads per cm per longitudinal row

= No. of weft threads per cm per longitudinal row.

From these definitions it follows that:

No. of ground warp threads per cm.sup.2 = NY .times. NZ

No. of binder warp threads per cm.sup.2 = NX .times. NY

No. of weft threads per cm.sup.2 = NX .times. NZ

IF SX, SY, and SZ represent the desired strength in grammes per cm.sup.2 of the fabric in the three directions and if DX, DY and DZ represent the denier of the ground warp, the weft, and the binder warp respectively, and if sx, sy and sz represent the strength in grammes per denier of the ground warp, weft and binder warp respectively, then the following relations apply:

SX = DX .times. NY .times. NZ .times. sx

SY = DY .times. NX .times. NZ .times. sy

SZ = DZ .times. NX .times. NY .times. sz

Furthermore, in any one horizontal or vertical plane the number of threads per cm and the yarn denier must be related in such a way that adjacent threads touch each other in order to ensure the stability of the structure. This condition is fulfilled when the following approximate relationships apply:

NX .times. (.sqroot.DY + .sqroot.DZ) = 800

NY .times. (.sqroot.DX + .sqroot.DZ) = 800

NZ .times. (.sqroot.DX + .sqroot.DY) = 800

Once the required strengths of the fabric have been fixed and a choice has been made of the materials to be used in the three systems of threads, it is necessary to reduce the number of unknowns to 4, for example by choosing two of the six unknowns NX, NY, NZ, DX, DY and DZ. The other four can then be calculated.

EXAMPLE I

It is desired to produce a fabric of 20 cm width and 10 cm thickness with a strength of 150,000 grammes per cm.sup.2 in all three directions. The same yarn is to be used in all directions and its strength is 1 gramme per denier.

From the dimensions of the fabric it follows that the reed must be approximately 22 cm wide and have a vertical clearance of approximately 12 cm. The height range over which weft insertion must take place is 10 cm.

Having decided to use 3,000 denier yarn for the ground and binder warps then by substituting in the six equations the values SX = SY = SZ = 150,000 and sx = sy = sz = 1 one finds that the equations are satisfied when:

NX = NY = NZ = 7 threads per cm per row of threads

DY = 3,000 denier.

Because NY = 7, the number of dents per cm in the reed must be 2 .times. 7 = 14. The number of vertical columns of ground warp threads is 20 .times. 7 = 140 and therefore the total number of binder warp ends is 140 - 1 = 139.

The total number of ground warp ends is 140 .times. 10 .times. 7 = 9,800.

Because the thickness of the fabric is uniform, the binder warp can be supplied to the machine from beams and since the total number of binder warp ends is small, one beam will be sufficient.

The number of ground warp ends, however, is large for a yarn of 3,000 denier and therefore several ground warp beams have to be used. (In this case approximately ten).

The total length of ground warp yarn required for a given length of fabric is, however, approximately equal to the total length of binder warp yarn and since the two yarns are of equal denier, the total weight of yarn on the one binder warp beam must be substantially the same as the total length of yarn on all the ground warp beams.

EXAMPLE II

It is desired to produce a fabric of 30 cm width and 5 cm thickness with different strengths in the three directions viz:

Sx = 250,000, sy = 160,000, sz = 80,000. the same yarn is to be used in all directions and its strength is 1 gramme per denier.

In this case, the reed must be 32 cm wide and have a vertical clearance of 7 cm.

The height range over which weft insertion takes place is 5 cm.

Having decided to use 6,500 denier yarn for the ground warps and 1,500 denier yarn for the binder warps the six equations are satisfied when:

NX =8.0

NY = 6.7

NZ = 5.7

DY = 3,500

Because NY = 6.7, the number of dents per cm in the reed must be 2 .times. 6.7 = 13.4. The number of vertical columns of ground warp threads is 30 .times. 6.7 = 201 and therefore the total number of binder warp ends is 201 - 1 = 200.

The total number of ground warp ends is given by the product of the number of vertical columns (201) and the number of ends in each vertical column (5 .times. 5.7). The latter quantity must be an integral number and therefore a choice has to be made between 28 ends per vertical column which would result in a fabric of slightly less than 5 cm thickness or 29 ends per vertical column resulting in a fabric of slightly more than 5 cm thickness. The total number of ground warp ends is thus either 201 .times. 28 = 5,628 or 201 .times. 29 = 5,829.

As in Example I, the binder warp can be supplied from one beam and the ground warp from several beams.

The invention is of course not limited to particular details set out hereinbefore by way of example. For instance, the invention is by no means restricted to the production of fabrics of rectangular cross-section as the cross-sectional shape can clearly be selected as desired by varying the number of ground warp threads contained in a vertical column and horizontal row. The following example illustrates such a case:

EXAMPLE III

It is desired to produce a fabric which in its basic structure corresponds to the fabric described in Example I but has a circular cross-section of 10 cm radius.

The principles involved in producing circular or other non-rectilinear section fabrics are basically the same as those involved in producing rectangular fabrics, but apply to each individual horizontal row or vertical column of ground warps rather than to the array of ground warps as a whole.

The maximum width and maximum thickness of this fabric are 20 cm and therefore the reed must be 22 cm wide and have a vertical clearance of 22 cm.

The height range over which weft insertion takes place is 20 cm.

Because NY = 7, the number of dents per cm in the reed must be 2 .times. 7 = 14.

The maximum number of vertical columns of ground warp ends is 20 .times. 7 = 140 and therefore the total number of binder warp ends is 140 - 1 = 139.

The number of ground warp ends per cm.sup.2 of cross-sectional area is 7.sup.2 = 49 and therefore the approximate total number of ground warp threads will be 49 .times. 10.sup.2 .times. .pi. = 15,386. The accurate number of ground warp ends has to be found by drawing a circle on point paper and filling it in with vertical and horizontal rows of points of density 7 per cm.

Because the thickness of the fabric varies along its width, being a minimum at the two sides and a maximum at the centre, the amount of binder warp required for a given length of fabric is also at a minimum at the sides and at a maximum at the centre. It is therefore not possible to withdraw all the binder warp ends from one beam and each end will have to come from a separate package mounted on a creel.

Since the fabrics produced by the present invention will usually be of much greater thickness and rigidity than conventional fabrics, they cannot normally be coiled up on a roller in the conventional manner. They must be withdrawn from the weaving machine in a substantially rectilinear path. When using the fabric (made say from carbon fibre threads) as reinforcements for relatively short components of metal or plastics material, means could be provided at the output end of the weaving apparatus for cutting off appropriate lengths of fabric and incorporating them as reinforcements in suitable materials while under such tension and by such means as will cause the desired fabric dimension to be maintained. Adhesive may be applied to the ends of each length to prevent fraying.

On the other hand, if it is desired to produce long lengths for storage against future use additional mechanism must be provided to support the fabric as it is withdrawn from the weaving apparatus so as to prevent sagging. The length of fabric which can be produced in one piece will normally be limited by space considerations.

Claims

I claim:

1. A weaving machine adapted to produce a structure comprising straight group warps extending longitudinally of said structure in three dimensional array, said array being rows of ground warps and columns thereof at right-angles to the rows, a plurality of binder warps, and a single continuous weft extending alternately back and forth in substantially straight paths across the width of said structure and throughout the depth of said array, the machine comprising in combination, means for holding each ground warp in position in its respective row and column during commencement of weaving, ground warp row separating means operative to separate each successive ground warp row from its adjacent row independently and in sequence, weft-insertion means adapted to lay successive straight portions of a single continuous weft between successive separated ground warp rows in opposite directions each of which is generally and substantially at right angles to the longitudinal extent of said ground warps and across the width of said array, and guide means adapted to lay-in said binder warps with said ground warps and said wefts in a direction generally and substantially at right angles to the longitudinal direction of said ground warps and through the depth of said array.

2. A weaving machine according to claim 1, in which the weft-insertion means comprises, in combination, first and second drive means for respectively passing a shuttle between two separated ground warp layers and adjusting the shuttle height relative to the structure.

3. A weaving machine according to claim 2, in which the first drive means comprises at least one pair of shuttle-carrying rapiers simultaneously inserted from opposite sides of the structure, the shuttle being transferred from one rapier to the other while in the gap between separated ground warp layers, respective arms pivotally supporting said rapiers for reciprocating movement into and out of said gap, and links connected to said arms and to crank means for imparting reciprocating motion to the arms and hence to the rapiers.

4. A weaving machine according to claim 1, in which the guide means comprises a heald frame carrying heald wires for the binder warps, means for reciprocating the heald frame to produce the laying-in motion for the binder warps, and a spring-loaded tension bar over which the binder warps are fed prior to passing through the heald frame.

5. A weaving machine according to claim 4, in which means for reciprocating the heald frame comprise a bell crank mechanism actuated through linkages by a cam adapted to operate in synchronism with the weft-insertion means.

6. A weaving machine according to claim 1, further comprising a reed, and means for reciprocating the reed for beat-up purposes.

7. A weaving machine adapted to produce a structure having a three-dimensional array of ground warps arranged in a series of rows and columns, a plurality of binder warps and a plurality of wefts, the machine comprising in combination, means for holding said ground warps in said three-dimensional array during commencement of weaving, ground warp layer separating means comprising two columns of separating bars arranged in pairs disposed so that successive rows of ground warps may pass between the two bars of each successive pair and means for raising said pairs of bars independently in sequence, weft-insertion means adapted to lay straight spaced wefts between separated ground warp layers in a direction which is generally and substantially at right angles to the longitudinal extent of said ground warps and across the width of said array, guide means adapted to lay-in said binder warps with said ground warps and said wefts in a direction generally and substantially at right angles to the longitudinal direction of said ground warps and through the depth of said array, and means for linearly progressing said structure as it is woven.

8. A weaving machine according to claim 7, in which each pair of bars form one end of a rectangular framework, each framework being independently pivotable about a common axis with the other frameworks, said shedding bars being disposed to one side of the pivot axis, the other end of each framework being connected at the other side of the pivot axis to the jacks of a dobby.

9. A weaving machine adapted to produce a structure having a three-dimensional array of ground warps, a plurality of binder warps and a plurality of wefts, the machine comprising in combination, means for holding said ground warps in said three-dimensional array during commencement of weaving, ground warp layer separating means, weft-insertion means adapted to lay straight spaced wefts between separated ground warp layers in a direction which is generally and substantially at right angles to the longitudinal extent of said ground warps and across the width of said array, said weft-insertion means including first and second drive means for respectively passing a shuttle between two separated ground warp layers and adjusting the shuttle height relative to the structure and further including means operatively connecting the second drive means with the first drive means and means for operating the second drive means to adjust the height of the shuttle in timed relationship with operation of the first drive means, guide means adapted to lay-in said binder warps with said ground warps and said wefts in a direction generally and substantially at right angles to the longitudinal direction of said ground warps and through the depth of said array, and means for linearly progressing said structure as it is woven.

10. A weaving machine adapted to produce a structure having a three-dimensional array of ground warps, a plurality of binder warps and a plurality of wefts, the machine comprising: in combination, means for holding said ground warps in said three-dimensional array during commencement of weaving; ground warp layer separating means; weft-insertion means adapted to lay straight spaced wefts between separated ground warp layers in a direction which is generally and substantially at right angles to the longitudinal extent of said ground warps and across the width of said array, said weft-insertion means including first and second drive means for respectively passing a shuttle between two separated ground warp layers and adjusting the shuttle height relative to the structure, said first drive means comprising at least one pair of shuttle-carrying rapiers simultaneously inserted from opposite sides of the structure, the shuttle being transferred from one rapier to the other while in the gap between separated ground warp layers, respectively arms pivotally supporting said rapiers for reciprocating movement into and out of said gap, and links connected to said arms and to crank means for imparting reciprocating motion to the arms and hence to the rapiers, and said second drive means comprising a pinned plate intermittently driven in synchronism with the rapiers by a double pallet mechanism which is movable to reverse the direction of rotation of said pinned plate, a nut mounted on said pinned plate, a lead screw mounted in said nut for rotation and axial movement as said pinned plate rotates, and support means mounted on said lead screw for supporting the rapier support arms so that the rapier and shuttle height relative to the structure is adjusted as said lead screw rotates in said nut; guide means adapted to lay-in said binder warps with said ground warps and said wefts in a direction generally and substantially at right angles to the longitudinal direction of said ground warps and through the depth of said array; and means for linearly progressing said structure as it is woven.

11. A weaving machine adapted to produce a structure having a three-dimensional array of ground warps, a plurality of binder warps and a plurality of wefts, the machine comprising in combination, means for holding said ground warps in said three-dimensional array during commencement of weaving, ground warp layer separating means, weft-insertion means adapted to lay straight spaced wefts between separated ground warp layers in a direction which is generally and substantially at right angles to the longitudinal extent of said ground warps and across the width of said array, guide means adapted to lay-in said binder warps with said ground warps and said wefts in a direction generally and substantially at right angles to the longitudinal direction of said ground warps and through the depth of said array, and means for linearly progressing said structure as it is woven, including a pair of driven spaced horizontal rollers and a pair of driven spaced parallel vertical rollers, the spacing of the rollers of each pair being adjustable to suit the fabric dimensions.