CN113825866A

CN113825866A - Shed forming device

Info

Publication number: CN113825866A
Application number: CN202080036347.5A
Authority: CN
Inventors: B.范德朱格特
Original assignee: Vandewiele NV
Current assignee: Vandewiele NV
Priority date: 2019-06-20
Filing date: 2020-06-19
Publication date: 2021-12-21
Anticipated expiration: 2040-06-19
Also published as: US20220316103A1; CN113825866B; ES2970174T3; WO2020255066A9; EP3987094C0; EP3987094B1; EP3987094A1; BE1027384A1; BE1027384B1; WO2020255066A1

Abstract

The invention relates to a shed forming device comprising a jacquard device (2), in which jacquard device (2) heddles (16), (17) are connected to pullback elements (18), (19) for exerting a downward force on the heddles (16), (17), wherein for each heddle (16), (17) there is a yarn tensioning element (8) for varying the yarn tension in at least one associated warp yarn (11), (12), and a control or steering unit is provided for steering or controlling the yarn tension in at least one associated warp yarn (11), (12) for each heddle (16), (17) respectively, so that the total downward force on the heddles (16), (17) reaches a specific value or varies according to a specific curve.

Description

Shed forming device

Technical Field

The invention relates to a shed-forming device comprising a jacquard device with a plurality of heddles for positioning at least one associated warp yarn, wherein each heddle is connected to a pullback element for exerting a downward force on the heddle.

Background

In a continuous weft insertion cycle on a weaving machine, one or more weft yarns are inserted into a shed formed between warp yarns. In order to weave according to a predetermined weaving pattern, it is necessary to correctly position the individual warp threads in each shed with respect to one or more weft insertion heights. Jacquard machines are used to position a number of warp yarns differently in each shed.

The positioning is performed with heddles connected to respective hooks by cords, wherein each heddle has a heddle eye. The hook can be moved up and down by means of a blade moving up and down and selected by means of a selection device to be held or not held in one of a number of possible positions. Each warp thread passes through a heddle eye of a heddle, whereby each different position of the heddle corresponds to a different position of a warp thread.

In order for shed formation to take place correctly and for the downward movement of the hook to be facilitated, each heddle is connected to a back-draft spring for exerting a downward force on the heddle. In the lowest position of the heddle, the amount of tension of the spring is at its minimum, so that the downward force exerted by the retraction spring on the heddle is minimal. The retraction spring is selected such that this minimum force is still just sufficient to allow the hook connected to the heddle to engage correctly on the selected edge of the blade.

In the lowest position of the heddle, the warp thread passing through the heddle eyelet also exerts an upward force on the heddle. This is caused by the yarn tension in these warp yarns. In this lowest position, the retraction spring must therefore exert a downward force on the heddle that is greater than the upward force, and the resultant downward force must also be just sufficient to allow the selection hook to engage on the selection edge of the blade. Therefore, this minimum downward tension cannot be too small.

When the heddle is moved by the blade to a higher position, the downward spring force increases proportionally with the upward movement of the heddle, eventually reaching a value much greater than that required. As a result, the average tension on the warp yarns is much higher than desired. Higher tension means greater wear of the machine parts, more general and frequent damage to the warp yarns themselves and greater energy consumption of the machine.

Disclosure of Invention

The object of the present invention is to remedy these disadvantages.

This object is achieved by providing a shed-forming device having the features described in the first paragraph of this specification, wherein, according to the invention, for each heddle, the shed-forming device comprises a yarn tensioning element for varying the yarn tension in at least one associated warp yarn, the shed-forming device further comprising a control or operating unit cooperating with the respective yarn tensioning element for operating or controlling, respectively, the yarn tension in at least one associated warp yarn for each heddle such that the total downward force on the heddle reaches a specific value or varies according to a specific curve.

The inventive shedding device can be used to manipulate or control the tension profile in the warp yarns such that the combined effect of the yarn tension and the spring always exerts a downward force on the heddle that is large enough to achieve good shedding but reaches a maximum value that is lower than when using existing shedding devices. This means less wear, less yarn damage and lower energy consumption.

Furthermore, less powerful retraction elements may be selected. At the lowest heddle position, the yarn tension can still be manipulated or controlled to a lower value than when using existing shed-forming devices. Thus, the retractor must provide a low force to achieve the minimum downward force necessary.

The steering or control system may also be designed to allow the total downward force during weaving to assume a plurality of predetermined continuous values. In some cases, certain machine parameters (e.g., machine position or machine speed) or data related to the weave pattern or weave structure may also be provided to the steering or control system for consideration in determining a target value for the total downforce.

The curve may for example be selected from a set of two or more reference curves or two or more reference sequences (e.g. tables or files) having at least one reference value for the yarn tension. In this way, during weaving, an appropriate reference curve or reference sequence can be selected, for example, depending on machine parameters and/or weaving pattern data.

In a preferred embodiment, each yarn tensioning element comprises a roller driven by a motor and in contact with at least one warp yarn and destined to rotate in one or the other direction of rotation to move said warp yarn in the opposite direction to the feeding direction of the warp yarn, or to move the warp yarn or to promote the movement of the warp yarn, so as to move with the movement of the warp yarn (i.e. the moving warp yarn) in the same direction as the feeding direction of the warp yarn, to increase or decrease, respectively, the yarn tension in said warp yarn.

The retraction element may be any type of element designed to apply a force, such as other elements that provide a force at least partially through a pneumatic drive element and/or gravity. Preferably these elements are elements which provide the downward force at least partially, preferably completely or predominantly, by means of an elastically deformable element. In a most preferred embodiment, the retraction element is a spring.

The thread tensioning device preferably comprises a measuring device for measuring the thread tension or a measure of the thread tension in at least one warp thread or in a plurality of (at least two) warp threads forming a group. Preferably, the control unit further comprises means for repeatedly or continuously comparing the measured yarn tension or yarn tension measurement variable with a reference value and for generating a control signal for driving the yarn tensioning element (for example by adjusting the current of the control motor or by adjusting the motor torque) in the event of a difference between the measured yarn tension or variable and the reference value, such that the difference between the measured value and the reference value is reduced.

The control unit preferably comprises a regulator for generating a control signal for driving the yarn tensioning element (for example by adjusting the current of the control motor or by adjusting the motor torque) so as to approach or reach a specific target value of the yarn tension when this target value is set. The regulator is preferably a "feed forward control" type regulator.

In a particular embodiment of the steering or control unit, machine parameters (e.g. machine position or machine speed, or data relating to the weaving pattern or structure) may also be obtained, and one or more of these parameters may be used for control or steering.

If one or more yarn tension influencing conditions are different for different warp yarn subgroups, in the weaving machine different reference yarn tension profiles can be determined for the subgroups and adjusted individually depending on the conditions that have changed during the weaving process and differently in the different subgroups as required during weaving. This allows the average value of the yarn tension to be kept slightly lower, while the maximum value of the yarn tension is not so high.

The yarn tensioning device comprises, for example, detection means for detecting the state of one or more yarn tension influencing conditions during weaving, and/or comprises memory means and/or data processing means to predefine the times or phases during weaving at which a yarn tension influencing condition occurs according to the weaving pattern and/or according to a recommended warp path between the yarn store and the fabric.

In this weaving machine, the method according to the invention preferably employs a control system with a "bidirectional forced feed-forward function". This means that when the movement of the yarn changes, the yarn tensioning unit intervenes to promote this change, and thus reacts more quickly.

Further specific features of the shed-forming device are specified in the claims.

The invention will now be further explained with reference to the following more detailed description of one possible embodiment of the jacquard machine according to the invention. It is emphasized that the described apparatus and method are merely examples of the general principles of the invention, and thus should not be taken as limiting the scope of the invention, as defined in the claims, or the application of the invention.

Drawings

In the detailed description, reference is made to the accompanying drawings using reference numerals, wherein:

fig. 1 is a schematic side view of the structure of a weaving machine and a creel with associated yarn tensioning devices;

fig. 2 is a graph of the following situation for a pile-forming warp yarn in a plurality of successive weft insertion cycles during weaving, according to the prior art:

development of the position of the heddle eyelet (in millimetres),

the development of an upward or downward component (in newtons) of the force acting on the heddles due to the yarn tension in the pile-forming warp yarns,

the development of the downward spring force (in newtons) of the back-pull spring acting on the heddles of the pile warp, and

the development of the sum of the downward spring force (in newtons) on the heddles and the upward or downward component (in newtons) of the force acting on the heddles due to the yarn tension in the pile-forming warp yarns;

fig. 3 is a graph of the following for a pile-forming warp yarn in a plurality of successive weft insertion cycles during weaving with controlled or manipulated yarn tension in the present invention:

development of the position of the heddle eyelet (in millimetres),

the development of the downward spring force (in newtons) of the back-pull spring acting on the heddles of the pile warp,

the development of the sum of the downward spring force (in newtons) on the heddle and the upward or downward component (in newtons) of the force acting on the heddle due to the yarn tension in the pile-forming warp yarns, and

-an average of the sum of said forces.

Detailed Description

In a particular installation, a weaving machine (1) cooperating with a jacquard (2) is mounted beside a creel (3), and a creel (4) with four rollers (40) - (43) each containing a yarn storage is arranged in the space between the weaving machine (1) and the creel (3).

The yarn tensioning device (6) is mounted in the space between the creel (3) and the weaving machine (1) and consists of a yarn tensioning module (20), which yarn tensioning module (20) extends in a horizontal direction parallel to a vertical plane containing the front sides (30a) of a plurality of adjacent creel units (30). The thread tensioning module (20) comprises two plate-like carriers (21), (22) with flat outer surfaces, which travel towards each other symmetrically with respect to the horizontal in the direction of the weaving machine (1), wherein they are brought together and joined together at an angle. The thread tensioning module (20) has a V-shaped profile, seen in vertical section. Each carrier (21), (22) carries a number of rows of thread tensioning elements (8) arranged closely adjacent to each other. For the sake of clarity, only three yarn tensioning elements (8) are shown for each carrier (21), (22). For each warp yarn that is guided from a respective bobbin in the creel (3) to the loom (1), a guide tube (10) is provided to guide the warp yarn without tension to the respective yarn tensioning element (8).

The warp yarns are further moved from the yarn tensioning element (8) to a grid (100) having the same width as the yarn tensioning module (20), but having a smaller height. The warp threads (11), (12) run from the grid (100) to the weaving machine (1), where they pass through the heddle eyes of the respective heddle (16), (17), here the heddle is symbolically shown with a vertical line representing a circular widening of the heddle eye. A respective retraction spring (18), (19) exerts a downward force on each heddle (16), (17).

According to the prior art, the warp yarns are supplied in a stretched state from a creel (3) to a first grid (X). Fig. 1 shows the prior art case, in which a straight line (S1) from the uppermost row of bobbins in the creel (3) passes first through the grid (X) of the prior art device and then onto the grid (100); the straight line (S2) passes from the bottom row of bobbins in the creel (3) through the grid (X) of the existing device and then onto the grid (100). The grid (X) is not part of the device of the invention and is added to the figure for the sake of clarity, only for comparison with the prior art, to present the effect of the invention.

The lines (S1), (S2) show the size of the angle (relative to the horizontal) at which the warp yarns of the prior art are brought to the grid (X) and then onto the grid (100), thus showing the angle the supplied warp yarns subsequently take.

During weaving, the heddles (16), (17) are moved up and down to correctly position the warp threads (11), (12) according to a predetermined weaving pattern. The retraction springs (18), (19) at their lowest positions provide the necessary downward force to make shed formation proceed correctly, but must also overcome the upward force due to yarn tension.

If the heddle is moved to a higher position for shedding, the downward spring force increases proportionally with the upward movement of the heddle, eventually reaching a value much greater than necessary.

In fig. 2, for a plurality of successive weft insertion cycles (the state of the main shaft of the loom is shown on the horizontal axis in degrees), the line G1 in the figure shows the development of the downward force of the springs (18), (19) acting on the heddles (16), (17) of the pile-forming warp yarns (in newtons on the left-hand vertical axis); line G2 in the figure shows the development of an alternating upward and downward component of the force (in newtons) acting on the heddles (16), (17) due to the yarn tension in the pile-forming warp yarns. The latter force is hereinafter referred to simply as "yarn tension".

For the sake of clarity, in fig. 2 and 3, the force (spring force or yarn tension) is marked negative, which means that the force pulls the heddle upwards. This is clear, for example, because in the pattern area where the heddle is in the lowest position, the yarn tension is negative. It is clear that the force exerted on the heddle by the yarn tension has an upward component that pulls the heddle upwards.

The line G4 in the figure shows the position of the heddle eyelet (on the right vertical axis, in mm).

The development of the sum of the spring force and the yarn tension is shown by line G3 in the figure. Here, two peaks (P1), (P2) of this total force can be seen. The line G3 in the figure shows the forces to which the different machine parts are subjected. It should be noted that the graphs in fig. 2 and 3 show the forces resulting from the movement of a single pile warp yarn, whereas on a typical double-layer fabric loom, for example, there may be more than 32000 pile warp yarns.

Fig. 3 shows the development of the spring force and the yarn tension on the heddles of the pile-forming warp yarns when the yarn tension is controlled or manipulated to obtain a lower peak value and a lower average value of the sum of the spring force and the yarn tension.

Due to this manipulation or control, it is also possible to use a spring with a lower spring constant and a lower spring pretension (below 0.15 newton), which is the downward spring force when the heddle is in the lowest position. The pretension may be lower because the pile warp exerts less upward yarn tension due to manipulation or control of the yarn tension.

In fig. 3, the same reference numerals (G1), (G2), (G3) and (G4) as in fig. 2 are used for the lines in the figure, and they have the same meanings: namely the development of the downward spring force (G1), the development of the yarn tension (G2), the development of the sum of the spring force and the yarn tension (G3) and the position of the heddle (G4). The left vertical axis gives the value of the force (in newtons) and the right vertical axis gives the value of the heddle position (in millimetres). The horizontal axis represents the state of the loom main shaft in degrees.

The line (G5) (dashed line) in the figure gives the average value of the sum of the spring force and the yarn tension.

It can clearly be seen from the line (G3) in the figure that the peak has disappeared for the total force on the heddle (compared to the peaks P1 and P2 in fig. 2). Furthermore, the average value of this total force is low. In the design without a steering or control system (fig. 2), the calculated average of this total force is 2.91 newtons, whereas in the design with a control system, the total force is 2.72 newtons (line G5 in fig. 3).

These effects mean that the load on the machine is low, wherein it also cannot be forgotten that the values in the diagram show the forces resulting from the movement of a single pile warp, whereas on a typical double-layer fabric weaving machine, for example, there may be more than 32000 pile warp yarns.

The advantageous aspects of the invention are not limited to pile warp yarns but also apply to another type of warp yarn positioned by a jacquard device or to a single-face weaving machine.

Claims

1. Shed-forming device comprising a jacquard device (2) having a plurality of heddles (16), (17) for positioning at least one associated warp yarn (11), (12), wherein each heddle is connected to a haul-back element (18), (19) for exerting a downward force on the heddle (16), (17), characterized in that, for each heddle (16), (17), the shed-forming device comprises a yarn tensioning element (8), which yarn tensioning element (8) is intended for varying the yarn tension in at least one associated warp yarn (11), (12), the shed-forming device comprising a control or handling unit, which cooperates with the respective yarn tensioning element (8), for handling or controlling the yarn tension in at least one associated warp yarn (11), (12) for each heddle (16), (17), respectively, so that the total downward force on the heddles (16), (17) reaches a specific value or varies according to a specific curve.

2. Shed-forming device according to claim 1, characterized in that each yarn tensioning element (8) comprises a roller which is driven by a motor and which is in contact with at least one warp yarn and is intended to rotate in one or the other direction of rotation in order to move the warp yarns (11), (12) in the direction opposite to the direction of feed of the warp yarns, or to move the warp yarns (11), (12) in the same direction as the direction of feed of the warp yarns or to move with the movement of the warp yarns or to facilitate the movement of the warp yarns in order to increase or decrease, respectively, the yarn tension in the warp yarns.

3. Shed forming device according to claim 1 or 2, characterized in that parameters of the jacquard device (2) or of the weaving machine (1) cooperating with the jacquard device, or data or parameters relating to the weaving pattern, are supplied to the control or steering unit for taking into account in determining the target value for the total downward force.

4. A shed-forming device according to any one of the preceding claims, characterized in that it comprises a memory unit in which two or more reference yarn tension curves and/or two or more reference sequences of at least one reference value for yarn tension are stored, and that the control or steering unit is arranged to select a reference curve or reference sequence from the set to be used as a steering or controlled target value or a series of target values.

5. The shed-forming device according to any one of the preceding claims, characterized in that the retracting element is a spring (18), (19).