Method of weaving with increased crossing of warp and weaving loom for performance of the method

Technical field The invention relates to the weaving method with increased crossing of warp.

The invention further relates to the weaving loom for weaving with increased crossing of warp comprising the warp beam with package of warp threads, device for shed creating, loose weaving reed, device for inserting of weft into shed and cloth roller for winding of fabric.

Background art

Forming of the fabric is a force process, in result of which the inserted weft pushes into the wedge spacing between the pre-stressed warp threads and it is crossed by warp threads until the required interlacing structure is achieved. Upon pushing the weft into the fabric the resistance of warp threads against deformation must be overcome (wave and elongation of thread elements) as well as the frictional resistance among the threads. Collectively these forces are called weaving resistance. This resistance must be overcome by an active force, usually by a beating force, which is created by mutual acting of weaving reed and fabric face due to drawing of the system fabric - warp. It can be said, that this physical model and the corresponding technical means for its realisation, first of all the weaving reed with slay and the drive mechanism is, without any exemption, applied on all types of weaving looms. Also the parameters of mechanisms for creation of the shed (lifting and angle of opening of warp threads) during the time stabilised on certain values similar for all types of single-shedding looms.

In the time interval of beating pulse on the woven-in weft from the side of fabric the drag force is acting, whose value is proportional to the value of nominal axial force in the thread and value of crossing angle. This angle, depending on the sett and thread fineness, may reach the values up to 60°.

From the side of warp during weaving-in the weft, the crossing angle is nearly zero and also in the phase of maximum opening of the shed, it reaches the values less than 15°. Within whole interval of a weaving cycle the weft is being pushed out from the fabric as a result of unbalanced elastic forces in the fabric and warp. The only and not always effective means to overcome the weaving resistance and weaving-in the weft are the beating force and friction between threads.

Literature discloses a theory, that the possible way for inducing a force effect upon the weft during its forcing into warp threads is so called excessive crossing of warp threads. The basic force in warp threads may thanks to distribution in force polygon create a component, which overcomes the weaving resistance and will form the fabric. The resultant force, which is induced by one warp thread to the weft element is: F = N • cos Cp ₁ - N • e ^{f α} • cos φ ₂ . In the domain of realistic parameters (Cp ₁ , 9 ₂ , f) the pressure force will obtain the values which are similar to the beating force. Due to these reasons and also due to irregular force in various warp threads depending on their position on the stand (edge, centre), due to fluctuation in forces during weaving process or due to irregularities in warping, to achieve straightness of weft and desired sett, it is useful to combine the pressure force with beating force of the weaving reed. The weaving reed may have a lower lifting, because the area for weft insertion thanks to opening of warp may occur close to beating point. Reduction in dimensions of weaving reed means reduction of weight upon preserving or increasing its rigidity. At the same time it is advantageous during the weaving cycle to combine the force effect of beating force (force impulse, work of weaving reed during weft weaving-in) with force effect achieved by an excessive crossing of warp threads (it is not an algebraic sum of forces, as both forces act in a different time interval). The sum, respectively repeating of force effects during weaving-in of one weft after then has a positive impact on shift of weft in warp and on achievement of a higher quality in binding points, and practically it will result in smaller spacing of weft , respectively higher sett of fabric, which is a certain analogy with multiple beating. The importance of weaving technology with increased crossing of warp threads is more expressive

with increasing working frequency of weaving loom, as an impulse of beating force is decreasing and weaving becomes more difficult. Not of a lesser significance for increasing of frequency is the fact, that the lifting of working members of weaving mechanisms and after then their inertial forces may be reduces considerably.

Practical utilisation of weaving theory with increased crossing of warp threads (warp) is nevertheless precluded by the need of enormously high lift of weaving shafts to achieve the desired opening angle of the shed, as the dynamic forces corresponding to these lifts and required rotations of the machine cannot be managed by present means and technologies.

The goal of the invention is to enable a practical utilisation of the weaving theory with increased warp crossing.

The principle of invention The goal of the invention has been reached through the weaving method with increased crossing of warp, whose principle consists in that the shed for one working cycle is produced in two synchronised sectors, out of which in the first, pulse sector, the warp threads are separated into branches according to the specified pattern of weaving, and in the second, force sector, an increased crossing of warp branches separated in the pulse sector is performed, through which overcoming of weaving resistance is achieved and a space for weft insertion is created, while the activity in both sectors runs continuously and mutually synchronised.

In this way it is possible to weave efficiently and effectively with increased warp crossing and so fully use the advantages of weaving with increased crossing of warp. Another advantage is that in the pulse sector it is possible to separate the threads only with reduced angle of opening when compared with angle of opening necessary for conventional weaving, through which it is possible to save an important portion of energy otherwise necessary for activity of the device in the pulse sector. Moreover the device in the pulse sector need not be so efficient as at the shed device for conventional weaving.

The principle of weaving loom for weaving with increased warp crossing consists in that, the shedding mechanism comprises a device of pulse sector for separation of warp threads into branches, and device of the force sector for performance of increased crossing of warp, while both devices are driven synchronously.

This machine enables weaving with increased crossing of the warp.

Advantageous embodiments of the method and weaving loom are shown in dependent claims and also result from description of exemplary embodiments.

Description of the drawing

The invention is schematically shown in the drawing, where the Fig. 1 represents one exemplary embodiment of weaving loom for weaving with increased crossing of warp, the Fig. 2 another exemplary embodiment of weaving loom for weaving with increased crossing of warp, the Fig. 3 exemplary embodiment of gripper for realisation of second phase of shed with increased crossing of warp, and the Fig. 4 represents schematic arrangement of the shed according to the invention.

Examples of embodiment

The weaving method with increased crossing of warp is such, that creating of shed for each working cycle of weaving loom is divided into two sectors IZ, SZ, out of which in the first sector, which in further text will be designated as pulse sector IZ, a separation of warp threads into branches according to the specified weaving pattern is performed, and in the second sector, which in further text will be designated as force sector SZ, an increased crossing into branches of separated warp threads is performed, at the same time the activity in both sectors IZ, SZ is running constantly and mutually synchronously. Angle of opening of threads in pulse sector IZ in example of embodiment represented in the Fig. 4 is considerably smaller than the angle of opening of threads at conventional sheds according to the present state of the

art and it does not correspond to dimensions of weft carrier, i.e. it does not enable weft insertion, as this is enabled not until in the sector SZ of increased crossing. In the not represented example of embodiment the angle of opening of threads is different, e.g. like at the conventional shed. In each of both sectors IZ, SZ the activity runs constantly, while frequency and phase of activity in each sector IZ, SZ are mutually synchronised.

Weaving loom for weaving with increased crossing of warp will be described on an example of embodiment of several weaving looms, which comprise some identical or similar assemblies and some different assemblies. Arrangement of weaving loom is known for a specialist, so individual parts of the machine, which are not directly connected with the present invention, will not be described.

The represented weaving loom comprises pulse sector |Z, which in the represented example of embodiment is realised by a conventional device for shed creation, which is either of cam or shaft type. In the not represented example of embodiment the device forming the pulse sector IZ is formed by another suitable device for separation of warp threads into branches according to the prescribed pattern of weaving, e.g. it is formed by non-conventional separation or shedding mechanism of suitable parameters. In the following text for description of invention a weaving loom will be used whose pulse sector IZ is formed by a shaft shedding mechanism, while for an average specialist the adaptation of invention to the weaving loom with cam shedding mechanism means a common engineering practice, same as adaptation of invention to the future types of conventional or unconventional shedding mechanism or device for separation of warp threads into branches. The device with pulse sector ]Z realises constantly the required lifting function with desired frequency and phase.

The weaving loom with pulse sector IZ formed by shaft shedding mechanism comprises a system of weaving shafts 2, whose straight-lined reversible motion is secured by a shedding mechanism, as a rule by a cam shedding mechanism, whose activity is controlled by a controlling device. The

weaving shafts are in a known manner provided with healds ±, Y_, which comprise the known eyelets Ia, Ia^, through which the warp threads Ib, IJbT are passing on their way between the not represented warp beam and the not represented cloth roller. In the direction X from the warp beam there is behind the pulse sector

IZ, i.e. in the represented example of embodiment behind the weaving shafts 2 situated the weaving reed Ijc, which is provided by a row of known dents having space between one another, while the warp threads are passing through the weaving reed Ic through space between the dents. The weaving reed Ic is positioned on a reversibly adjustable slay Id, which in the example of embodiment in the Fig. 1 is formed by a spring parallelogram connected with a cam drive or in an example of embodiment in the Fig. 2 it comprises reversibly rotatably mounted shaft with blowing nozzles etc. In a not represented example of embodiment the slay Id may be created in another suitable manner, which nevertheless is not decisive for the principle of the invention itself.

In the direction X from the warp beam behind the pulse sector IZ, i.e. in the represented example of embodiment behind the weaving reed 1c, there is situated the known not represented device for weft insertion into the shed Ie. The weft inserted into the shed ^e after then during weaving is transported by a weaving reed λc_ on the slay λ<\ into the face If of fabric l£, which is gradually wound on the not represented cloth roller.

The warp threads Ib, IJtT are passing between the weaving reed Ic and pulse sector JZ, i.e. in represented example of embodiment through weaving shafts 2, between the force sector SZ, in which on the warp threads separated into branches the increased crossing of warp is realised.

In the represented example of embodiment the force sector SZ is realised by means of separation unit H and gripper 8.

The separation unit ϋ in the represented example of embodiment comprises a system of stationary parallel vertical lamellas 12, whose pitch need not be the same as pitch of dents of weaving reed Ic or pitch of healds

1, I!. ^so that through one space between the lamellas λ2 even several warp

threads may pass. Lamellas 12 of separation unit H in a section corresponding to lifting of warp threads ^b, IJ/ by acting of device of pulse sector IZ are sloped towards the vertical direction, so that the warp threads JLb, It/ being lifted or dropped by device of pulse sector JZ by acting of lamellas 12 of the separation unit H are simultaneously moving into sides, e.g. during motion upwards they are simultaneously moving to the right and during motion downwards they are simultaneously moving to the left, etc. It is also possible that warp threads Ib, IJT being lifted or dropped by device of pulse sector IZ by acting of lamellas 12 of separation unit H in the first phase of shed creation move traverse towards direction of the shed creation to the same side.

Due to the side separation motion of warp threads Ib, IJ/ induced by the device of pulse sector IZ and by separation unit JM the warp threads Ib of upper part of shed are shifting e.g. upwards to the right towards the shaft shedding mechanism, while the warp threads JM/ of lower part of shed are shifting e.g. downwards to the left towards the shaft shedding mechanism.

To the separation beam i± the catching means of gripper 8 are assigned, which catch the warp threads IJb, JN/ for realisation of increased crossing of warp. The gripper 8 is coupled with driving device, which constantly and with required frequency and phase towards the device of pulse sector IZ realises the required lifting function. Thanks to this the gripper 8 is able to realise an increased crossing of warp in the force sector SZ accurately according to the time schedule corresponding to co-operation with other parts of the loom, especially with the device of pulse sector ]Z and its lifting function. The gripper 8 may to the separation beam V\_ be assigned either from the side of weaving reed Jk:, as represented in the Fig. 1 , or from the side of pulse sector |Z, as represented in the Fig. 2.

In example of embodiment represented in the Fig. 1 there is performed the gripper 8 with straight-lined reversible motion. In this embodiment the gripper 8 comprises a pair of bars 14 with cuts 15, inlet openings 16 and retaining hooks 17. The cuts 15, inlet openings t6 and hooks 17 correspond to the spacing between lamellas λ2 of separation unit H and enable catching of warp threads of respective branch of shed on the hooks J[7. The bars 14 are

coupled with the straight-lined reversible drive, which provides for a continuous motion of bars 14 upwards and downwards with the required frequency, phase and amplitude.

In example of embodiment represented in the Fig. 2 there is performed the gripper 8 with rotation reversible motion, when on a pair of reversible rotating shafts 18 are mounted the catching means 18a of warp threads IJb, UbJ^ separated by a device of pulse sector JZ and shifted to the side by the separation unit IJ.. The shafts 18 are coupled with rotating reversible drive, which ensures continuous reversible motion of shafts 18 with required frequency, phase and amplitude. In this example of embodiment the separation unit H is situated in direction of warp threads from pulse sector IZ with healds

1 only after the gripper 8.

Lifting functions of device of pulse sector IZ and device of force sector SZ are mutually synchronised so that, the device of pulse sector IZ and the device of force sector SZ continuously execute their lifting function with desired frequencies, phases and amplitudes.

Between the device of pulse sector IZ and device of force sector SZ in the represented example of embodiment there is situated the separator of pulse sector IZ and force sector SZ. In example of embodiment represented in the Fig. 4 the separator is formed by a pair of separating rods 19.

One weaving cycle with increased crossing of warp according to the invention runs so that the warp threads are by means of pulse sector IZ separated into upper and lower branch of the shed. During this separation the warp threads are guided into catching means of the device of the force sector SZ, e.g. to the hooks 17. The device of force sector SZ takes each of the branches of the shed and realises an increased crossing of warp. In a specified moment in force sector SZ there is performed the weft insertion through the shed with increased crossing, beating of weaving reed and return of the device of force sector SZ back, there follows releasing of branches from the device of force sector SZ and catching of new branches of the shed by the device of force sector SZ. After then another weaving cycle follows. At the same time the

devices of pulse and force sector |Z, SZ execute their function and mutually in a synchronous manner with desired frequency, phase and amplitude.

The invention is not limited only to the embodiments expressly described or represented here, but it could be realised without exercising any inventive step also by means of further structural means.

Applicability

The invention may be used in the weaving looms.

List of referential markings

1 heald r heald

1a heald's eyelet

1a' heald's eyelet

1b warp thread

1b' warp thread

1c weaving reed

1d slay

1e shed

1f fabric face ig fabric

11 separation unit

12 lamella of separation unit

14 bar

15 cut in the bar

16 inlet opening

17 retaining hook

18 shaft

18a catching means of warp threads

19 separating rods

2 weaving shaft

8 gripper

X direction

IZ pulse sector

SZ force sector