EP1867765B1 - Device for forming a Jacquard-type shed, loom equipped with such a device and method of forming the shed on such a loom - Google Patents

Abstract

The device for forming a Jacquard type shed, comprises electrical actuators, and units for controlling the actuators. The control unit generates a signal representing the value of a parameter determined by a calculator for each actuator, and comprises a unit for automatically analyzing a design corresponding to an anterior pick and posterior pick and an element for determining a modification factor on the basis of result of the analysis conducted by the analyzer. The analyzer and the element are formed by or belong to the calculator. The device for forming a Jacquard type shed, comprises electrical actuators, and units for controlling the actuators. The control unit generates a signal representing the value of a parameter determined by a calculator for each actuator, and comprises a unit for automatically analyzing a design corresponding to an anterior pick and posterior pick and an element for determining a modification factor on the basis of result of the analysis conducted by the analyzer. The analyzer and the element are formed by or belong to the calculator. Memory units are arranged for storing a parameter depending upon the design, and for storing values of modification factor. The values of modification factor are associated with a value of a parameter determined by the analyzer. Independent claims are included for: (1) a process for forming a Jacquard type shed; and (2) a weaving loom.

Description

The invention relates to a Jacquard-type shedding device for a loom and to a loom equipped with such a device. The invention also relates to a method of forming the crowd on such a craft.

In the field of crowd formation, it is known to WO-A-90/01081 electrically controlling electrical actuators in a Jacquard loom. It is also known to EP-A-1,559,816 , using computers controlling electric actuators to move the arches of a Jacquard harness to control the movement of the rails between two high and low positions, which allows to form the crowd for each pick. A Jacquard harness can have more than 12,000 individually ordered arches to draw over 20,000 picks.

The crowd being defined as the trajectory of the smooth over time, the parameters of crowd can be the amplitude of the movement, its form, its temporal offset with respect to a reference which can be the cross or its vertical offset with respect to a reference plane that can be the sheet of son at the crossing. When it is necessary to modify the crowd parameters, the weaver must make many adjustments to these parameters which are long, tedious and, consequently, sources of errors.

It is these drawbacks that the invention intends to remedy more particularly by proposing a new device for forming the crowd which simplifies, to a very large extent, the programming work of the weaver when a new design has to be implemented. on a trade or when crowd parameters need to be changed.

• un analyseur apte à analyser automatiquement, pour une duite, le dessin correspondant à une ou plusieurs duites et
• un organe de détermination d'un facteur de modification, sur la base du résultat de l'analyse conduite par l'analyseur, de la valeur du paramètre déterminée par le calculateur.

For this purpose, the invention relates to a Jacquard-type crowd-forming device comprising a plurality of electric actuators as well as control means for these actuators able to generate, for each actuator, a signal representative of the value of at least one parameter determined by a calculator. This device is characterized in that the control means comprise, for at least one actuator,

• an analyzer able to automatically analyze, for a pick, the drawing corresponding to one or more picks and
• a factor for determining a modification factor, based on the result of the analysis conducted by the analyzer, of the value of the parameter determined by the computer.

For the purposes of the present invention, a pick corresponds to a cycle of insertion of a frame. The drawing defines the fabric. It contains at least the armor of the drawing and, optionally, other elements such as information on the type of frame to be inserted at each pick. The weave of a fabric defines the position of the thread or wires that each actuator controls with respect to the weft and for each pick. The armor is conventionally represented by a table whose columns correspond to the actuators and the lines to the picks. A box blackened or comprising a cross means that the son or wires controlled by the actuator of the column pass above the frame for the pick considered in a line. Conversely, a white box means that the son or wires controlled by this actuator pass under the frame for the pick in question. From a computer point of view, the position of the wires controlled by an actuator can be stored on one bit per pick. This bit takes the value 1 when the wires ordered must be above the frame and 0 when they must be below.

A pick lasts a business blow, or 360 ° rotation of the main shaft of the trade. At the beginning of a pick, the moving threads are at the crossing, that is to say, substantially in the vicinity of a median plane of the crowd. They reach their extreme high or low position when the business angle is shifted about 180 ° from the beginning of the pick.

Thanks to the invention, the analyzer and the factor of determination of the modification factor make it possible to obtain automatically, that is to say without human intervention, a dynamic adaptation of a control parameter of an actuator, This prevents the weaver from having to program each actuator or group of actuators individually.

According to advantageous but non-obligatory aspects of the invention, such a device can incorporate several of the features of claims 2 to 6.

1. - a) analyser pour au moins un actionneur, le dessin correspondant à une ou plusieurs duites, et
2. - b) modifier éventuellement la valeur d'au moins un paramètre de commande de l'actionneur en fonction du résultat de l'analyse de l'étape a).

The invention also relates to a method of forming the shed on a loom, which method can be implemented by the device mentioned above. In this method, arcades of a Jacquard type armor mechanism are controlled by means of a plurality of electric actuators controlled by means capable of generating, for each actuator, a signal representative of a calculated parameter. This method is characterized in that it comprises automatic steps consisting, for at least one pick, of:

1. a) analyzing for at least one actuator, the drawing corresponding to one or more picks, and
2. b) possibly modifying the value of at least one control parameter of the actuator as a function of the result of the analysis of step a).

Thanks to the invention, one can take into account, for an actuator, the drawing corresponding to one or more picks in order to automatically adjust one of the control parameters of this actuator. In other words, the method of the invention is to dynamically modify the crowd by appropriately controlling the actuators.

According to advantageous but non-obligatory aspects of the invention, such a method may incorporate one or more of the features of claims 8 to 18.

Finally, the invention relates to a loom equipped with a crowd forming device as mentioned above, such a job being easier and more economical to operate than those of the state of the art.

• la figure 1 est une représentation schématique de principe d'un métier à tisser conforme à l'invention incorporant un dispositif de formation de la foule conforme à l'invention ;
• la figure 2 est une représentation schématique de principe des moyens de commande d'un actionneur du dispositif de la figure 1 ;
• la figure 3A est un tableau représentant les différents types d'armure possibles pour une série de cinq duites, ainsi que des valeurs numériques associées dans le cadre de l'invention ;
• la figure 3B est une représentation schématique de différents types de profil utilisés pour le calcul des paramètres de commande des actionneurs ;
• la figure 4 est un schéma bloc représentant un premier procédé conforme à l'invention ;
• la figure 5 est une représentation schématique de principe des déplacements des lisses en fonction de la position angulaire de l'arbre métier au cours du tissage, lors de la mise en oeuvre du procédé de la figure 4 ;
• la figure 6 est une vue analogue à la figure 5, lors de la mise en oeuvre d'un second procédé conforme à l'invention ; et
• la figure 7 est une vue analogue à la figure 5, lors de la mise en oeuvre d'un troisième procédé conforme à l'invention.

The invention will be better understood and other advantages thereof will appear more clearly in the light of the following description of an embodiment of a shedding device, a loom and several methods in accordance with its principle given solely by way of example and with reference to the appended drawings in which:

• the figure 1 is a schematic representation of a weaving machine according to the invention incorporating a shedding device according to the invention;
• the figure 2 is a schematic representation of the principle of the control means of an actuator of the device of the figure 1 ;
• the figure 3A is a table representing the different types of armor possible for a series of five picks, as well as associated numerical values within the scope of the invention;
• the figure 3B is a schematic representation of different types of profiles used for the calculation of actuator control parameters;
• the figure 4 is a block diagram representing a first method according to the invention;
• the figure 5 is a schematic representation of the principle of the displacements of the hinges as a function of the angular position of the business tree during the weaving, during the implementation of the method of the figure 4 ;
• the figure 6 is a view similar to the figure 5 during the implementation of a second method according to the invention; and
• the figure 7 is a view similar to the figure 5 during the implementation of a third method according to the invention.

The loom M schematically represented at the figure 1 is equipped with warp yarns 1 each passing through an eyelet 2 of a hinge 3 animated by a vertical oscillation movement represented by the double arrow F ₁ , this movement being generally perpendicular to the direction of engagement of the weft yarns in the crowd, this direction being represented by the double arrow F ₂ . Each arm is connected by a cord 4 to a pulley 5 driven in rotation by an electric servomotor 6 forming an actuator for the pulley 5. In its lower part, each arm 3 is connected by a rod 7 to a return spring 8 secured to the frame 9 of the trade M.

In practice, the number of actuators 6 of the trade M can be 12,000 or more.

To control all or part of the actuators 6, a central computer C ₁ is used, in conjunction with several remote computers C ₂₁ , C ₂₂ , C ₂₃ ... C _2i , where ia a value adapted to the number of actuators 6. Each calculator C ₂₁ or equivalent is disposed near the servomotors 6 that it controls. The calculators C ₂₁ and equivalents are connected to the central computer C ₁ by means of dedicated electrical connections L ₂₁ , L ₂₂ , L ₂₃ , ... L _2i . The computer C ₁ receives a signal S ₁ representative of the instantaneous position of the tree of the trade M in its cycle. This signal corresponds to the instantaneous position of its main shaft 10 and can be measured by its angular position θ relative to a reference position.

The computer C ₁ is connected to an electronic unit U ₁ in which are stored the data relating to the drawing, including the information concerning the desired armor, that is to say the pattern to be made during weaving. According to the drawing D to be produced, the computer C ₁ receives from the unit U ₁ a signal S ₂ representative of this drawing.

The computer C ₂₁ is associated with a memory M ₂₁₁ forming a library in which are stored values representative of profile types P ₁ to P ₈ shown in FIG. figure 3B or algorithms for calculating these values.

These types of profile P ₁ to P ₈ correspond to the types of movement of an eyelet 2, as a function of the angular position θ of the main shaft of the loom during time t, in a vertical direction ZZ 'corresponding to the direction of the double arrow F ₁ . The profile types P ₁ , P ₂ , P ₃ and P ₄ correspond to a change of position with respect to the frame of an eyelet, whereas the profile types P ₅ , P ₆ , P ₇ and P ₈ correspond to holding in position relative to the frame.

The figure 2 represents the control of the actuator 6 ₁ , it being understood that the control of the other actuators 6 ₂ to 6 _k by the computer C ₂₁ is similar.

At each duite d _n given, whose n number is noted in the succession of picks corresponding to the weaving of a complete drawing D, the computer C ₂₁ has access to a memory M ₂₁₂ in which the positions are stored relative to each other. to the weft adopted for the two previous picks, positions that are respectively noted Pos (d _n-2 ) and Pos (d _n-1 ), as well as the position relative to the weft to be adopted for the current pick, note that Pos (d _n ), and the position with respect to the frame to be adopted for the next two picks, that we note Pos (d _{n + 1} ) and Pos (d _{n + 2} ). Thus, the computer C ₂₁ has information relating to the positions to be respected for five successive picks, including the current pick, for the rail 3 actuated by the servomotor 6 ₁ . These five positions relative to the weft constitute what is called a portion of armor made by the smooth.

During operation of a loom M, and when it is a question of controlling the servomotor 6 ₁ , at the beginning of a given pick d _n , the computer C ₂₁ receives from the computer C ₁ a signal S ₂₁ indicating to it the position relative to the weft Pos (d _{n + 2} ) that will have to take the smooth 3 for the second pick according to the pick in question, namely the pick referenced d _{n + 2} .

The values stored in the memory M ₂₁₂ are shifted step by step, the value Pos (d _n-1 ) taking the value Pos (d _n-2 ) and so on.

• l'amplitude maximum Amp du déplacement souhaité pour l'actionneur 61,
• le type de profil souhaité Pc pour un changement de position par rapport à la trame pour cet actionneur,
• le type de profil Pm souhaité pour un maintien en position par rapport à la trame pour cet actionneur,
• le décalage de croisure Δθ du profil souhaité pour cet actionneur,
• le décalage ΔZ vertical du profil par rapport à un plan de référence, qui peut être la hauteur de la nappe au croisement, pour cet actionneur

Memories M ₂₁₄ associated with the computer C _{21 also} contain,

• the maximum amplitude Amp of the desired displacement for the actuator 61,
• the desired profile type Pc for a change of position with respect to the frame for this actuator,
• the type of profile Pm desired for holding in position relative to the frame for this actuator,
• the crest offset Δθ of the desired profile for this actuator,
• the vertical offset ΔZ of the profile with respect to a reference plane, which may be the height of the sheet at the intersection, for this actuator

Amp, Pc, Pm, Δθ, and ΔZ are basic shedding parameters for a given actuator 6.

From the armor which is transmitted to it and the parameters of crowds, the computer C ₂₁ is able to determine the law of displacement of the beam 3 driven by the actuator which it controls for an interval corresponding to the length of d 'a pick. This interval starts at 180 ° from the beginning of the pick and ends at 540 ° from this beginning.

In practice, the position setpoint of each actuator is calculated in the computer C ₂₁ for a given period Δt. In other words, the set value K ₁ ... K _k of each actuator 6 ₁ , 6 ₂ , ..., 6 _k is a succession of instantaneous reference values. The calculated value K ₁ ... K _k thus calculated is then input in the form of a signal S ₂₁₁ ... S _21k in a control unit A ₂₁₁ ... A _21k dedicated respectively to the control of each actuator 6 ₁ , 6 ₂ , ..., 6 _k .

The computer C ₂₁ carries out an analysis of the armor enabling it to determine the value of the shedding parameters which are to be transmitted in the form of a signal S ₂₁₁ to a control unit A ₂₁₁ of the servomotor 6 ₁ .

This analysis is carried out automatically, that is to say without human intervention, on the five picks centered on d _n and whose respective positions are contained in the memory M ₂₁₂ .

If we go back to figure 3A where the boxes marked with an "X" correspond to the cases where a rail is arranged in the upper layer of the crowd, whereas the white boxes correspond to the cases where a rail is arranged in the lower layer of the crowd, it is noted that the combinations of movement between the high and low positions of the rails are 32 in number if we consider five successive positions of a rail.

From a computer point of view, the positions with respect to the Pos (d _n-2 ), Pos (d _n-1 ), Pos (d _n ), Pos (d _{n + 1} ) and Pos (dn + 2) frames ) wires controlled by an actuator are coded on a bit. This bit takes the value 1 when the ordered wires must be above the frame and the value 0 when they must be below. To differentiate the thirty two different combinations of positions between them and considering a pick d _n , we concatenate Pos (d _n-2 ), Pos (d _n ), Pos (d _{n + 1} ) and Pos (d _{n + 2} ) in a binary word of 5 bits. Under these conditions, each combination of five boxes in a column in the upper part of the figure 3A can be associated with a binary value. For example, the column marked with an arrow F ₃ can be associated with the binary value 01010 equivalent to the decimal value 10.

In the same way, the column indicated by the arrow F ₄ can be associated with the decimal value 13.

On the figure 5 the law of movement of the arm 3 actuated by the servomotor 6 ₁ is represented as a function of the angle θ of the main shaft of the loom. The value Δθ in this figure corresponds to 360 ° of rotation of the shaft, or a pick. For clarity of the present description, the dotted line L ₁ represents the law of motion of a Smooth through a taffeta armor and visualize the cycles of the trade M.

In the case shown in solid line at the figure 5 , the beam is held in the high position during the first four turns of trade and then passes alternately from a high position to a low position, with a taffeta movement, from the fifth lap of the craft.

The packing of a warp yarn is defined as the difference between its length when it is extracted from the fabric and the length of the fabric. Clogging a taffeta string is longer than wrapping a five-satin string for which the binary armor sequences are 01111, 10111, 11011, 11101, and 11110 However, if two warp son come from the same beam, differences in embossing due to different armor followed by these warp son are likely to create appearance defects. To reduce these differences, it is possible to offset the warp warp threads, especially by advancing the cross threads that perform a taffeta compared to the threads that make a satin of five. Indeed, in this case, the flap is more effective.

In these circumstances, as shown in figure 5 , the motion of the arm 3, which is represented by the solid line L ₂ in this figure, is modified so that it follows a curve that is offset with respect to the sinusoid L ₁ .

If we consider the fourth pick of d ₄ , for which we can define the values corresponding to the two previous picks d ₂ and d ₃ and the following picks d ₅ and d ₆ , the curve L ₂ crosses the median plane of the crowd, that is to say, reaches the crossing, with a lower angle θ of a value dθ equal to 20 ° with respect to the value at which it crosses the median plane along the line L ₁ .

In other words, the weaver can associate with each value V an offset dθ corresponding to a lead of the race when the succession of picks d _n-2 , d _n-1 , d _n , d _{n + 1} and d _{n + 2} corresponds to a taffeta, that is to say to the configuration of the columns indicated by the arrows F ₃ and F ₅ on the figure 3A .

It is sufficient for the weaver to determine the relationship between the line of the values V and the line of the offsets dθ to be predicted, as indicated in FIG. figure 3A , so that this relationship is automatically implemented at each pick by the computer C ₂₁ . In practice, a table corresponding to the last two lines of the figure 3A is stored in a memory M ₂₁₃ which is accessed by the computer C ₂₁ , as shown in FIG. figure 2 .

The operation of the computer C ₂₁ , for the control of the actuator 6 ₁ for a pick d _n , follows the flowchart shown in FIG. figure 4 . In a prior step 100, the computer C ₂₁ receives the signal S ₂₁ from the computer C ₁ . In a first step 101, the value of the position Pos (d _{n + 2} ) for the pick d _{n + 2} is stored in the memory M ₂₁₂ . In a second step 102, the computer accesses the memory M ₂₁₂ and retrieves the information relating to the Pos (d _n-2 ), Pos (d _n-1 ), Pos (d _n ), Pos (d _{n + 1} ) positions. , Pos (d _{n + 2} ) for the picks d _n-2 , d _n-1 d _n , d _{n + 1} and d _{n + 2} . On the basis of this information and on the basis of a table such as that shown in figure 3A the calculator C ₂₁ calculates, from the values of 0 or 1 associated with the picks d _n-2 , d _n-1 , d _n , d _{n + 1} and d _{n + 2} and in a third step 103, a value V corresponding to one of the columns of the figure 3A . In other words, from the analysis of the portion of the drawing corresponds to the actuator 6 ₁ for the pick d _n, the previous two picks and two posterior picks in 103 calculating a value V. step 104, the memory M ₂₁₃ is accessed and, from the calculated value V, it is determined which angular offset value dθ must be implemented for the cross.

This angular offset value being determined, it generates, in a step 105, the signal S ₂₁₁ corresponding to the values of the amplitude A to follow as a function of the angle θ. In other words, in step 105, the portion of the curve L ₂ corresponding to the interval extending from 180 ° to 540 ° after the beginning of the picking d _n is generated, after having corrected it if necessary. the factor dθ for the crossing angle at the crossing of the bar. The correction of the curve portion L ₂ is carried out optionally, insofar as it is implemented, if necessary, in the case where the factor dθ is non-zero. Thus, the combination of steps 104 and 105 makes it possible to modify the value of the amplitude A of the displacements to be generated by the actuator 6 ₁ as a function of the angle θ, that is to say of passing from the curve L ₁ to curve L ₂ at the figure 5 .

The calculator C ₂₁ can therefore be considered as having a first module C _'21 by which the drawing D corresponding to the current pick, the anterior picks and the posterior picks, and a second module C " ₂₁ in which, from the result of this analysis, ie from the value of V, the value of the offset dθ to be applied to the crosstitch is determined, this shift being in fact a factor for modifying or correcting the successive values , as a function of the angle θ, from the amplitude A to the figure 5 . These successive values of the amplitude A as a function of θ is transmitted to the control unit A ₂₁ as the signal S _211, unit A ₂₁₁ while driving the actuator 6 ₁ as a function of this signal.

According to non-represented aspects of the invention, the offset dθ may have a non-zero value also when the value of V is different from 10 and 21. For example, the value of dθ may be equal to 10 ° when V is 2, 4, 5, 6, 8, 9, 11, 12, 13, 14, 17, 18, 20, 22 and 26. This results from a choice of the weaver, this choice can be made as a rule followed for all the pick of the fabric, which avoids tedious programming.

In the embodiment described above, the table present in the memory M ₂₁₃ may be the same for all the actuators. In this case, the weaver must enter only the values corresponding to a single table, these values being able to be used for all the actuators and for all the picks. In this case, the memory M ₂₁₃ is common for all the computers C _2i and all the actuators 6. As a variant, the table present in the memory M ₂₁₃ is specific to each actuator or to each group of actuators, for example the actuators intended to weave the edge of the fabric.

The invention has been represented with a method in which the two previous picks and the two picks after the current pick are taken into account. It is applicable with a method in which only one anterior and / or one posterior duet is taken into account. It is also applicable to the general case for which account is taken of mites centered or not on the current pick. In this case, the table present in the memory M ₂₁₃ contains 2 ^m values to which a parameter V between 0 and 2 ^m -1 can be assigned.

The invention has been represented in the case where an offset dθ is determined that applies to the contemplated shift Δθ for an actuator. It also applies to the modification of one of the other Amp, Pc, Pm, or ΔZ crowd parameters.

In the foregoing description, two modules C _'21 and C'_{'21 have been identified} . In practice, these modules can be formed by a microprocessor forming the central part of the computer C ₂₁ , this microprocessor being programmed to successively play the role of the modules C _'21 and C'_{'21 as} well as to fulfill the other functions of the calculator C ₂₁ .

To the figure 2 , memories M ₂₁₁ , M ₂₁₂ , M ₂₁₃ and M ₂₁₄ have been shown outside the computer C ₂₁ - In practice, they can be integrated in this computer. To the figure 1 for the sake of clarity, only the memories associated with the computer C ₂₁ are shown.

According to a variant of the invention which is not shown, the calculation of the offset dθ may be performed in the main computer C ₁ for each of the actuators. In this case, the value of this offset is integrated in the signal S ₂₁ .

The invention has been described in the case where a central computer C ₁ and remote computers C ₂₁ , C ₂₂ ... C _{2i are used} . It is applicable in the case where a single computer is used for the control of an actuator 6.

The second embodiment of the invention shown in figure 6 relates to the case where the crowd parameters are modified according to an analysis of the drawing D of all the actuators 6 on a single pick.

It is known that the geometry of the open shed depends on the imbalance between the number of wires arranged respectively in the high position and in the low position. For a good performance and a good insertion quality, especially on a loom, the geometry of the crowd must remain as stable as possible. In order to obtain a good stability of the crowd, certain parameters of the crowd can be adjusted appropriately.

In this case, referring to the figure 1 , the analysis is performed at the level of the central computer C ₁ who has access to the data relating to all the actuators 6.

For example, the weaver can enter, in a memory similar to the memory M ₂₁₃ to which the computer C ₁ has access, an over-travel value dA to be applied, upwards or downwards, for each smooth according to the imbalance expected for the crowd, including the ratio between the number of son in the high position and the number of son in the low position for a future crowd.

In operation, at the beginning of each pick d _n , the calculator C ₁ evaluates the imbalance on the next pick d _{n + 1} from the knowledge he has of the positions of the son on this next pick. From this evaluation, the calculator C ₁ determines the modifications to be made to the corresponding shedding parameters, in particular the maximum amplitude changes Amp of the strokes of the rails, over a range extending from 180 ° to 540 ° of angle. profession after the beginning of the duite d _n . These modifications are addressed to the remote computers C ₂₁ ,... C _2i within the signals S ₂₁ ,... S _2i .

Thus, in the case illustrated in figure 6 the line L ₂ represents the stroke of a rail controlled by an actuator 6 as a function of the angle θ of the main shaft 10. The picks are considered according to their order number d ₁ , d ₂ , d ₃ . .. We define the value of the unbalance of the crowd for a pick d _n corresponding to the ratio between, on the one hand, the difference in the number of wires in the high position and the number of wires in the low position and, on the other hand , the total number of wires. This imbalance can be calculated, for each pick d _n and for all of the actuators 6, by the calculator C ₁ . The calculated value of the imbalance can be rounded to the nearest 0.1. We then obtain one of eleven values between 0 and 1.

For each actuator 6 and for each pick d _n , it is determined, as a function of the value of the imbalance provided for picking d _{n + 1} , which corrective action must be applied to the maximum amplitude Amp of the stroke of the rail, under the form of a positive or negative over-travel dA which makes it possible to compensate, at least in part, the imbalance envisaged for the picking d _n +1.

The first computer C ₁ determines the over-travel dA to apply and sends the corresponding information within the signal S ₂₁ , ... S _2i to each of the remote computers C ₂₁ , ... C _2i . The values of the overtravel dA can be different from one actuator to another.

Each remote computer C ₂₁ , ... C _2i takes into account the over-travel dA in the calculation of the position instructions sent to the actuators that it controls.

As a variant, instead of applying an overtravel dA and to compensate at least in part for the imbalance envisaged for picking d _{n + 1} , it is possible to envisage modifying the vertical offset ΔZ of the sheet of wires. The analysis of the pick of d _{n + 1} makes it possible to determine for each actuator 6 a modification value dZ of the crossing altitude to be applied, as a function of the imbalance at the crossing, by the addition of an offset value. dZ.

In the third embodiment of the invention shown in figure 7 , we take into account the choice of weft son used for each pick. This information can be part of the drawing. It is indeed possible that the characteristics of the weft son used from one pick to another vary, especially when using different weft son within the same fabric.

According to the invention, it is possible to modify the crowd parameters dynamically according to an analysis produced on the type of frame to be produced. To easily insert a weft yarn relatively large diameter, a very open crowd profile is required. However, the use of such a profile significantly increases the risk of breakage warp son. The invention makes it possible to reduce this risk.

In the example of the figure 7 it is considered that three types of profiles are available, namely a first type of substantially sinusoidal profile P ₁ , as represented between picks d ₁ and d ₃ and aligned on a sinusoid L ₁ , a second type of profile P ₁ more open than the profile type P ₁ and a third type of profile P " ₁ almost rectangular.

In this case, the weaver has entered in a corresponding table the type of profile P ₁ , P ' ₁ or P'' ₁ corresponding to each type of weft yarn used by having classified the weft son by diameter. For example, the fabric comprises three types of weft son T ₁ , T ₂ and T ₃ whose diameter increases from T ₁ to T ₃ . It is considered that the weaver respectively assigns the profiles P ₁ , P ' ₁ and P'' ₁ to the weft son T ₁ , T ₂ and T ₃ .

At the beginning of each pick d _n, the frame analysis is performed by the first computer C ₁ and is used to select the type of profile corresponding to the largest weft yarn inserted during the current pick d _n and the weft next d _{n + 1} . Indeed, the types of profiles being defined from one extreme position to another of the crowd, it should be considered two picks to choose the profile that will ensure the most appropriate passage volume.

Consider the point a at the beginning of the pick d ₇ . When the angle θ reaches the value corresponding to this point, the computer C ₁ analyzes the drawing to be made taking into account the weft son to be inserted during the pick d ₇ and d ₈ . If the wire to be inserted in the d ₈ die is of the T ₃ type, while the weft wire to be inserted at the d ₇ die is of the T ₁ type, the computer determines that the profile to be to apply from a point b which is shifted from point a to an angle value θ of 180 ° is the type of profile P '' ₁ which corresponds to the largest of the frames envisaged.

From point b, the computer C ₂₁ modifies the control parameters of the corresponding actuator to adopt, over an angle range of 360 °, the profile type P '' ₁ .

After picking d ₈ , and insofar as the weft threads inserted into picks d ₉ , d ₁₀ and d ₁₁ have a smaller nominal diameter, the type of profile P '' ₁ is gradually changed to the type of profile P ₁ , via the profile type P ' ₁ intermediate between these profiles P ₁ and P'' ₁ .

At the beginning of the pick ₉ , the computer determines that the type of profile to be applied between the points c and d is the type of profile P ' ₁ which has been assigned to the type of frame T ₂ by the weaver.

On the figure 7 the types of thread used are schematically marked at the level of each pick.

In each of the methods envisaged above, it is possible to modify the crowd parameters taking into account not only an analysis produced from the drawing to follow but also from an external data coming from the trade. For example, in the case of the third method envisaged above, it is possible to take account of the tension of the warp threads insofar as a relatively strong tension of the warp threads allows a better uncrossing of these threads, such so that it is not necessary to use very marked profiles. In the same way, it is possible to take into account an external parameter likely to influence the resistance of the wires, for example the humidity or the ambient temperature.

In the methods envisaged above, the step of modifying the parameter normally determined by the calculator is not systematic. Indeed, dθ can be zero in the first method, as dA in the second method. In the third method, if it is not necessary to change the type of profile, the profile type P ₁ is not modified.

Whatever the embodiment considered, the analysis of the drawing corresponding to at least one pick makes it possible to consider modifying the value of a control parameter of an actuator in order to improve the adaptation of the crowd to the drawing. sought, this in a dynamic and automated way, which prevents the weaver from having to individually program the movement of each of the smooth for each pick. The modified parameter (s) may be one or more of the Amp, Pc, Pm, Δθ, and ΔZ crowd parameters mentioned above.

The technical characteristics of the various embodiments envisaged can be combined with each other within the scope of the present invention. The methods envisaged above may only be applied for certain picks and / or certain actuators.

For the purposes of the present invention, a Jacquard loom actuator may control one or more louvers.

Claims (19)

1. Apparatus for the formation of a shed of the Jacquard type, comprising a plurality of electrical actuators (6) and command means (C₁, C₂₁, C₂₂ .....) for these actuators, adapted to generate, for each actuator, a signal (S₂₁₁) representative of at least one parameter (A) determined by a calculator (C₁, C₂₁, C₂₂), characterised in that the command means comprise, for at least one actuator,

   - an analyzer (C'₂₁) adapted to analyze automatically, for a pick (d_n), the pattern (D) corresponding to one pick or more (d_n-₂, d_n-1, d_n, d_n+1, d_n+2), and

   - a device (C"₂₁) for the determination of a factor (d⊖; dA; P'₁; P"₁) for the modification, on the basis of the result (V) of the analysis made by the analyzer, of the value (A) of the parameter determined by the calculator.
2. Apparatus according to claim 1, characterised in that the analyzer (C'₂₁) is adapted to analyze, for one pick (d_n), the pattern (D) corresponding to at least one previous pick (d_n-2, d_n-1) and one subsequent pick (d_n+1, d_n+2).
3. Apparatus according to any foregoing claim, characterised in that the analyzer (C'₂₁) is constituted by or is associated with the calculator (C₁, C₂₁, C₂₂ ...C_2j).
4. Apparatus according to any foregoing claim, characterised in that the device for the determination of the modification factor is constituted by or is associated with the calculator (C₁, C₂₁, C₂₂ ... C_2j).
5. Apparatus according to any foregoing claim, characterised in that it comprises a memory (M₂₁₂) for storing a parameter (Pos(d_n-2), Pos(d_n-1), Pos(d_n), Pos(d_n+1), Pos(d_n+2)), dependent on the pattern (D) corresponding to the pick as well as at least one previous pick (d_n-2, d_n-1) and at least one subsequent pick (d_n+1, d_n+2).
6. Apparatus according to claim 4, characterised in that it comprises a memory (M₂₁₃) for the storage of values of the modification factor (d⊖), these values each being associated with a value of a parameter (V) determined by the analyzer (C'₂₁).
7. Method for the formation of the shed on a weaving loom, for the command of the arches (4) of a weaving mechanism of the Jacquard type, by means of a plurality of electrical actuators (6) commanded by means (C₁, C₂₁, C₂₂ .....) for generating, for each actuator, a signal (S₂₁₁) representative of the value of a calculated parameter, characterized in that it comprises automatic stages consisting of, for at least one pick (d_n):

   a) - analyzing (102, 103), for at least one actuator, the pattern (D) corresponding to one or more picks (d_n-2, d_n-1, d_n, d_n+1, d_n+2) and

   b) - consequently modifying (104, 105) the value of at least one command parameter command for the actuator as a function of the result of the analyzing stage a).
8. Method according to claim 7 characterised in that:

   c) - during the stage a) the analysis is made for the pattern corresponding to the pick (d_n) as well as at least one previous pick (d_n-2, d_n-1) and/or at least one subsequent pick (d_n+1, d_n+2).
9. Method according to claim 7 or 8, characterised in that:

   d) - during the stage a) the pattern is analyzed for an actuator or a group of actuators on the basis of the high or low positions of the corresponding arch or arches and a parameter (V) is allotted a value representative of the successive positions of the arch or arches and

   e) - during the stage b) the allotted value is taken into account whether to modify or not (d⊖) the command parameter (A) of the actuator.
10. Method according to claim 9, characterised in that the value allotted during the stage a) is a whole number between 0 and 2^m - 1 where m is the number of picks analyzed during the stage c).
11. Method according to any of claims 7 to 10, characterised in that the consequentially modified parameter (A) influences the crossing angle of the arch or arches with a median plane of the shed.
12. Method according to claim 7, characterised in that:

    f) - during the stage a) the imbalance between threads in the high and low position in the shed is determined for a subsequent pick (d_n+1) and then a value representing this imbalance is allotted to a parameter and

    g) - during the stage b) the allotted value of the parameter is taken into account whether to modify or not (dA) the command parameter for the actuator.
13. Method according to claim 12, characterised in that the consequentially modified parameter influences the amplitude of displacement between high and low positions of the arch or arches controlled by the actuator (6) or the group of actuators.
14. Method according to claim 12, characterised in that the consequentially modified parameter (ΔZ) influences the height relative to a reference crossing plane of the warp threads.
15. Method according to claim 7 or 8, characterised in that

    h) - during the stage a) the type of profile (P₁, P'₁, P"₁) required for a subsequent pick (d_n+1) is determined and a value representative of this type of profile is allotted to a parameter and

    i) - during the stage b) the attributed value is taken into account whether to modify the command parameter of the actuator or not.
16. Method according to claim 15, characterised in that during the stage a) the type of profile (P₁, P'₁, P"₁) is determined while taking into account the diameter of the weft thread to be inserted during the subsequent pick (d_n+1).
17. Method according to claim 15 or 16, characterised in that during the stage b) the attributed value is taken into account for the selection of the type of profile (P₁, P'₁, P"₁) to be used as from the current pick (d_n).
18. Method according to any of claims 7 to 17, characterised in that during the stage a) a parameter external to the design, particularly the tension of the warp, is taken into account.
19. Weaving loom (M) equipped with apparatus for the formation of a shed (2-6, C₁, C₂₁, C₂₂... C_2i, V₁, M₂₁₁, M₂₁₂, M₂₁₃) according to any of claims 1 to 6.

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