Patent Description:
In the field of weaving, it is known to use a yarn-clamping device for clamping the different yarns of a warp yarn layer, in particular in a warp preparation process. Clamping the yarns of a yarn layer is needed, for instance, for tying two warp layers together or for drawing-in the warp yarns of a yarn layer into the harness of a loom.

In this context, <CIT> discloses a machine for automatically drawing-in warp yarns, where two pairs of yarn-clamping devices are mounted on a single yarn frame longitudinally movable relative to a drawing-in unit. A combination of relative adjustment along a longitudinal direction and along a yarn extension direction is possible between the two lower clamping rails. A first embodiment of the clamping device includes a comb introduced in a clamping housing delimited between a fixed wall and a movable wall whose movements may cause jamming of the comb with the clamping rail and blocking of some yarns between the comb and the clamping rail. Thus, even if it is globally satisfactory, such a drawing-in machine is difficult and expensive to implement. Another embodiment of the clamping device comprises an elastic tube driven by a rotating clamping bar, which are inserted within a clamping rail of a yarn-clamping device, in order to block the yarns within the rail. In insertion position of the elastic tube with the yarns between the tube and the clamping rail, the tube is already deformed against the clamping rail which exerts a first clamping action on the yarns that cannot be easily regularly distributed or tensioned in that position. Furthermore, unless when they are in the clamping position, the tube and the bar might be ejected from the clamping rail under the high tension in the yarns. In such a case, the yarn clamping process shall be started again from the beginning.

On the other hand, <CIT> discloses a yarn frame with two spaced clamping rails, each clamping rail being equipped with two rubber profiles and adapted for receiving a clamping rod. The two rubber profiles face each other and are parallel to each other. During tensioning of a yarn layer, the yarns are first clamped in one of the clamping rails, then tensioned before a turning rod is introduced in the other clamping rail. This approach may induce a loosening of the yarn tension and/or an irregular tension distribution along the yarn layer width. In addition, the rods introduced in the clamping rails may be ejected from these rails by the reaction effort exerted by the yarns or may have slight movements within the clamping rails in clamping position as the rods only cooperate with the rubber profiles, which might also cause an irregular yarn distribution. On the other hand, the two rubber profiles apply a relatively large friction effort on the yarns during rotation of the clamping rod. Depending on the type of yarns, this may cause uneven clamping of the yarns. Moreover, this approach does not allow using an intermediate position for adjusting the yarn position during clamping.

The present invention aims at solving these problems by providing an optimized yarn-clamping device which allows efficiently clamping the yarns without the risk of ejecting a clamping rod during the yarn clamping process.

With this respect, the present invention relates to a yarn-clamping device for clamping yarns of a yarn according to claim <NUM>.

Owing to the invention, since the internal surface of the rubber profile, in which the clamping rod penetrates for the clamping, is located on one side only of the main plane, the clamping rod in the clamping position cooperates only with the clamping rail on the other side of the main plane. The clamping position of the clamping rod within the clamping volume is thus better controlled. Since the clamping position is reached by rotation of the clamping rod within the clamping volume while the cooperation with the rubber profile occurs on only one side of the main plane, a more regular tension distribution within the yarn layer is obtained.

According to further advantageous aspects of the invention, the yarn-clamping device of the invention might incorporate one or several of the following features taken in any technically compatible configuration:.

According to a second aspect, the invention relates to a yarn frame which comprises at least a pair of yarn-clamping devices spaced along a yarn extension direction, whereas at least one of these yarn-clamping devices is as mentioned here-above.

Advantageously, the yarn frame is configured for clamping yarns of two yarn layers, wherein the yarn frame includes.

Still advantageously, the internal surface of the rubber profile of the yarn-clamping device according to the invention is located, within the clamping volume, on the same side of the main plane of the clamping volume as the other yarn-clamping device of the same pair of yarn-clamping devices.

According to a third aspect, the invention relates to a drawing-in machine for drawing-in warp yarns into a weaving harness, this drawing-in machine including a drawing-in unit and at least one yarn frame as mentioned here-above.

Advantageously, when the clamping rod is in the clamping position, the clamping rod partially protrudes through the insertion/extraction opening and out of the clamping rail, the drawing-in unit is movable relative to the yarn frame along the longitudinal axis of the clamping rail, and at least one roller longitudinally secured to the drawing-in unit is in contact with the clamping rod, which protrudes out of the clamping rail, for guiding the relative movement between the drawing-in unit and the yarn frame along the longitudinal axis of the clamping rail.

The invention will be better understood based on the following description, given as a non-limiting example and made in reference to the following figures:.

The drawing-in machine <NUM> represented on <FIG> includes a movable cart <NUM> and a fixed structure <NUM> supporting a drawing-in unit <NUM>, which can be of any known type and is represented by its outer shape.

The drawing-in machine <NUM> is designed for holding a first layer L1 and a second layer L2 of warp yarns in position for the drawing-in unit <NUM> to insert the warp yarns of these layers into a non-represented harness parts of a weaving loom, some of them being mounted on a support member <NUM> carried by the cart <NUM>. A harness is known per se and may include healds, a reed and sometimes drop-wires.

The two layers L1 and L2 are drawn from one or two non-represented warp beams and held by a yarn tensioning frame <NUM>, also called "drawing-in frame", which includes three posts <NUM>, some cross beams <NUM> and two beams <NUM> together forming the main structure of the frame <NUM>.

The yarn frame <NUM> is mounted on the fixed structure <NUM> and can be tilted with respect to this main structure, around an axis parallel to the longitudinal direction of the beams <NUM>.

Each beam <NUM> carries two yarn-clamping devices <NUM> arranged by pairs, respectively provided for holding the yarns of the yarn layer L1 and the yarns of the yarn layer L2 with respect to the yarn frame <NUM>. More precisely, a first yarn-clamping device <NUM> of each pair of yarn-clamping devices is mounted on the upper beam 16A, whereas a second yarn-clamping device of the same yarn-clamping devices pair is mounted on the lower beam 16B. Thus, the yarn frame <NUM> includes four yarn-clamping devices <NUM> in total.

As can be derived from <FIG> and <FIG>, the beams <NUM> are hollow, with a globally rectangular cross-section. Advantageously, the beams <NUM> have the same geometry. They can be cut in the same metallic profile.

On each beam <NUM>, the two clamping devices <NUM> are located next to each other, more precisely one above the other in the configuration of <FIG>, <FIG> and <FIG> in which the yarn frame <NUM> extends essentially in a vertical plane. The two yarn-clamping devices <NUM> of each pair are spaced along a yarn extension direction within the yarn layers L1 and L2, which is vertical on <FIG>, <FIG> and <FIG>.

A first pair of clamping devices <NUM> is formed by the lower yarn-clamping device 20A1 mounted on the upper beam 16A and by the upper yarn-clamping device 20B1 mounted on the lower beam 16B. This first pair of yarn-clamping devices <NUM> is for clamping the first layer L1. This first pair of yarn-clamping devices <NUM> is formed by the yarn-clamping devices 20A1 and 20B1 respectively mounted on each beam <NUM> on its side oriented toward the other beam.

The second pair of yarn-clamping devices <NUM> is formed by the upper yarn-clamping device 20A2 mounted on the upper beam 16A and by the lower yarn-clamping device 20B2 mounted on the lower beam 16B. The second pair of yarn-clamping devices is for clamping the second layer L2 of warp yarns. The second pair of yarn-clamping devices is formed by the clamping devices 20A2 and 20B2 respectively mounted on each beam <NUM> on a side of this beam opposite to the other beam.

Here above, references 20A1, 20A2, 20B1 and 20B2 are used to identify the four yarn-clamping devices. However, in the present example, unless it is specified otherwise, all four yarn-clamping devices are identical and the description of a generic yarn-clamping device identified with reference <NUM> applies to all yarn-clamping devices.

Each yarn-clamping device <NUM> includes a clamping rail <NUM>, a clamping rod <NUM> and two maintaining devices <NUM>, each maintaining device being assembled, at one respective longitudinal end of the clamping rail <NUM>, by screws <NUM>.

The clamping rail <NUM> is made of an aluminum profile, with a constant cross-section along a longitudinal axis X22 of the clamping rail. This cross-section is visible on <FIG> and has globally the shape of a C.

The clamping rail <NUM> has an inner cylindrical surface <NUM> with a circular cross-section of diameter D31 centered on the longitudinal axis X22. This inner cylindrical surface <NUM> partially delimits a clamping volume V22 within the clamping rail <NUM>. This clamping volume opens on a front face <NUM> of the clamping rail <NUM> via an opening O22, at the level of two portions 30a and 30b of an inner cylindrical surface <NUM>, with a cross-section in the form of arcs of a circle also centered on the axis X22, but having a diameter D30 smaller than the diameter D31.

The clamping rail <NUM> includes a longitudinal notch <NUM>, which forms a receiving housing for a rubber profile <NUM>, with a globally rectangular cross-section and a side planar surface <NUM> oriented toward the clamping volume V22.

The planar surface <NUM> forms an internal surface of the clamping volume V22 within the clamping rail <NUM>.

In a variant represented on <FIG>, the surface <NUM> is not a planar surface.

Y22 defines a transverse axis of the clamping rail <NUM>, perpendicular to axis X22 and which crosses the opening O22 in the middle of this opening. Axes X22 and Y22 are secant. Z22 defines a height or thickness axis of the clamping rail <NUM>, which is perpendicular to axes X22 and Y22. Axes Y22 and Z22 are parallel to the plane of <FIG> and respectively perpendicular and parallel to the front face <NUM>.

Portions 30a and 30b are at least partially turned toward the bottom of the clamping volume V22 at the opposite of the opening O22 along the transverse axis Y22. The front faces <NUM> of all clamping rails <NUM> of the yarn frame <NUM> extend substantially in the same plane, which is vertical in a drawing-in configuration.

The internal surface <NUM> of the rubber profile <NUM> is oriented toward the opening O22, with an inclination angle α between <NUM>° and <NUM>°, preferably equal to about <NUM>°, with respect to a main plane P22 of the rail <NUM>, containing axes X22 and Y22. The main plane P22 crosses the opening O22 in the middle of this opening. The inner cylindrical surface <NUM> extend on both sides of the main plane P22. In other words, portion 30a is situated on one side of the main plane P22 whereas portion 30b is situated on the other side of the main plane P22.

Surfaces <NUM> and <NUM> are approximatively flush, at the opposite of the opening O22 with respect to the rubber profile <NUM>. Together with the portions 30a and 30b of the surface <NUM>, they delimit the clamping volume V22.

A single longitudinal notch <NUM> is provided in the clamping rail <NUM> so that a single rubber profile <NUM>, or a single line of rubber profiles mounted in continuity along the axis X22, is located next to the clamping volume V22.

As can be derived from <FIG>, the rubber profile <NUM> of a yarn-clamping device 20A1 or 20A2 mounted on the upper beam 16A is located, within the corresponding clamping rail <NUM>, downwardly with respect to its clamping volume V22, that is on the side of the clamping rail oriented toward the clamping rail of the other yarn-clamping device 20B1 or 20B2 belonging to the same pair of yarn-clamping devices <NUM> along axis Z22. On <FIG>, the rubber profiles <NUM> of the two upper yarn-clamping devices 20A1 and 20A2 are located below their clamping volumes V22, whereas the rubber profiles <NUM> of the two lower yarn-clamping devices 20B1 and 20B2 are located above their respective clamping volumes V22. In other words, in each yarn-clamping device <NUM>, the internal surface <NUM> of the rubber profile <NUM> is located on a single side of the clamping volume V22, with regard to the main plane P22, this single side being oriented toward the other clamping device <NUM> of the same pair of clamping devices along axis Z22.

One or several spacers <NUM> can be received within the longitudinal notch <NUM> of each clamping rail <NUM> in order to adjust the projecting position of the internal surface <NUM> within the clamping volume V22.

The clamping rod <NUM> is made of a metal, such as aluminum or steel, and extends along a longitudinal axis X24, which is parallel to axis X22 at least in mounted configuration of the clamping rod <NUM> within the clamping volume V22.

As shown on <FIG> and <FIG>, the clamping rod <NUM> includes a central portion <NUM> configured to be received within the clamping volume V22, two end portions <NUM> having a generally square cross-section and two intermediate portions <NUM>. Each intermediate portion <NUM> is located, along the axis X24, between the central portion <NUM> and one of the end portions <NUM>, i.e. at a longitudinal side of the central portion <NUM>.

The cross-section of the clamping rod <NUM> along its central portion <NUM> is visible on <FIG>, whereas its cross-section along one intermediate portion <NUM> is visible on <FIG>.

At the level of its central portion <NUM> and as visible in particular on top of <FIG>, the clamping rod <NUM> is cylindrical, with a truncated circular cross-section defining, on one part of the periphery of the clamping rod <NUM>, a circular surface <NUM> centered on the axis X24 with a diameter D1 and, on the remaining part of this, a planar surface <NUM>. An external dimension d2, measured perpendicular to the axis X24, between this planar surface <NUM> and the most remote portion of the circular surface <NUM>, is strictly smaller than the diameter D1. Thus, the clamping rod <NUM> has, around axis X24, a non-circular profile in a cross-section taken in a plane perpendicular to the axis X24. P24 denotes a main plane of the rod <NUM>, which includes its longitudinal axis X24 and is parallel to the planar surface <NUM>. The maximum external dimension of the non-circular profile of the rod <NUM> extends parallel to the main plane P24 and equals diameter D1. This diameter D1 is larger than the maximum external dimension of the rod perpendicular to this main plane P24, that is distance d2. Diameter D1 is substantially equal to diameter D30, for example equal to <NUM>.

The square cross-section of the end portions <NUM> of the clamping rod <NUM> is adapted to cooperate with a non-represented tool, such as wrench, in order to exert a torque on the clamping rod <NUM>, around the axis X24.

At the level of one intermediate portion <NUM> and as visible, in particular, on top of <FIG>, the clamping rod <NUM> includes two planar and parallel surfaces <NUM> and <NUM> and two surfaces <NUM> and <NUM> in the form of portions of cylinders with a circular basis centered on a longitudinal axis. d2' denotes the distance between surfaces <NUM> and <NUM>, this distance being measured perpendicularly to these surfaces. Preferably, this distance d2' is slightly smaller than the dimension d2. D1' denotes the diameter of surfaces <NUM> and <NUM>. Preferably, this diameter D1' is slightly smaller than the diameter D1.

Along the axis X24, the planar surface <NUM> of an intermediate portion <NUM> extends the planar surface <NUM> of the central portion <NUM> toward the adjacent end portion <NUM>, whereas the planar surface <NUM> extends one of the planar surfaces of the end portion <NUM> toward the central portion <NUM>.

Each maintaining device <NUM> includes a body <NUM> made of a main body portion <NUM>, a support plate <NUM> and a cover <NUM> fastened all together. Parts <NUM> and <NUM> are provided with bores <NUM> for the passage of the screws <NUM>. The main body portion <NUM> is also provided with a threaded hole <NUM> for the reception of a screw <NUM> going through a bore <NUM> of the cover <NUM> and fixing the cover <NUM> and the main body portion <NUM> together.

The maintaining device <NUM> is used for limiting a rotation movement of the clamping rod <NUM> within the clamping volume V22.

The main body portion <NUM> defines a housing H26 for the reception of a C-shaped retaining member <NUM>. More precisely, the main body portion <NUM> has an internal cylindrical surface <NUM> with a circular cross-section centered on a central axis X60 of the body <NUM>. The main body <NUM> also has an end wall <NUM> which delimits axially the housing H26 on the one side, whereas the cover <NUM> delimits this housing on the other side, along axis X60.

The end wall <NUM> and the cover <NUM> are respectively provided with central apertures <NUM> and <NUM> for the passage of the clamping rod <NUM>. The two central apertures <NUM> and <NUM> have the same geometry.

The main body <NUM> is also provided with a through hole <NUM> which goes from the housing H26 to an external surface <NUM> of the main body <NUM>. This through hole <NUM> constitutes a housing for a shuttle <NUM> which is elastically biased by a spring <NUM> toward the housing H26, in such a way that a rounded end <NUM> of the shuttle <NUM>, opposite to the spring <NUM>, can protrude within the housing H26. A protrusion <NUM> is provided on the support plate <NUM> for centering the spring <NUM>. Thus, the support plate <NUM> cooperates with the main body portion <NUM> to support the shuttle <NUM> within the through hole <NUM>.

Y60 denotes a transverse axis of the body <NUM>, which is perpendicular to axis X60 and passes through the opening O26.

The movement of the shuttle <NUM> occurs along the longitudinal axis A90 of the shuttle, which is parallel to the axis Z22, i.e. transverse to the longitudinal axis X60 and to the axis Y60, in mounted configuration of the maintaining device <NUM> on the clamping rail <NUM>. The movement of the shuttle <NUM> toward the housing H26 is limited by a shoulder formed by an annular collar <NUM> of the shuttle <NUM> which comes into abutment against an inner shoulder <NUM> formed within the through hole <NUM>, as can be seen by the comparison of the two upper parts of <FIG>. The movement of the shuttle <NUM> away from the housing H26 is limited by the support plate <NUM>, which is immobilized onto the main body portion <NUM> by two screws <NUM> going through two orifices <NUM> provided in the support plate <NUM> and screwed in two threaded blind holes <NUM> provided in the main body portion <NUM>.

The shuttle <NUM> is provided with a through hole <NUM> transverse to its longitudinal axis A90. The through hole <NUM> is dimensioned in order to accommodate the ends of two transverse pins <NUM> housed in oblong slots <NUM> and <NUM> respectively provided in the main body portion <NUM> and in the cover <NUM>.

In practice, the transversal pin visible on the left of <FIG> goes through the slot <NUM> and a first portion of slot <NUM> in order to be engaged into the through hole <NUM> while still protruding out of the cover <NUM>. On the other hand, the transversal pin <NUM> visible on the right of <FIG> goes through a non-visible portion of the slot <NUM> which connects the through hole <NUM> to the face of the main body portion <NUM> perpendicular to the axis X60 and which is not visible on <FIG>. This transversal pin <NUM> also protrudes out of the main body portion <NUM>. With this arrangement, transversal pins <NUM> allow moving the shuttle <NUM> within through hole <NUM>, against the elastic action of the spring <NUM>, when necessary.

The retaining member <NUM> has an outer cylindrical surface <NUM> with a circular cross-section centered on a central axis X76 of the retaining member <NUM>. The retaining member <NUM> has two end surfaces <NUM>, <NUM> perpendicular to the axis X76, which respectively face the cover <NUM> and the end wall <NUM>, so that the retaining member <NUM> is secured, in a longitudinal direction parallel to axis X60, within the housing H26.

The body <NUM> has an opening O26 formed on a lateral face <NUM> of the main body portion <NUM> and on an edge of the cover <NUM> and which connects the housing H26 to the outside of the body <NUM>. W26 denotes the width of the opening O26, which is larger than the distance d2'.

In mounted configuration of the maintaining device <NUM> at one longitudinal end of the clamping rail <NUM>, the openings O22 and O26 extend next to each other along axis X22.

The axis Y60 is perpendicular to the lateral surface <NUM>. Z60 defines another transverse axis of the body <NUM>, which is perpendicular to axes X60 and Y60 and parallel to the lateral surface <NUM>. The axis Z60 is parallel to the longitudinal direction of the through hole <NUM> and to the longitudinal axis A90 of the shuttle <NUM>. The width W26 is measured parallel to the axis Z60. Axes X60, Y60 and Z60 are secant.

The outer surface <NUM> of the retaining member <NUM> matches with the internal cylindrical surface <NUM> which defines the housing H26, with a possibility of a movement of limited amplitude of the retaining member <NUM> within the housing H26 only in the direction of axis Z60. In other words, as can be seen by the comparison of the two upper positions represented on <FIG>, the retaining member <NUM> may move axially along axis Z60 within the housing H26, with a limited amplitude. The retaining member <NUM> is accommodated within the housing H26 without possibility of movement out of the housing H26 in the transverse direction parallel to the axis Y60, thus to the axis Y22, when the maintaining device <NUM> is mounted at one end of the clamping rail <NUM>. Globally, the housing H26 forms a guiding housing for guiding the retaining member <NUM> in rotation around axes X60 and X76 when they are superimposed.

The retaining member <NUM> defines a central notch <NUM>, which extends from the end surface <NUM> to the end surface <NUM> and between two planar and parallel surfaces <NUM> and <NUM> parallel to, and non-secant with, the axis X76. The axis X76 passes through the notch <NUM>. The retaining member <NUM> has a bottom <NUM> and two branches <NUM> and <NUM>, which respectively define the planar surfaces <NUM> and <NUM>, on either side of the notch <NUM>. The notch <NUM> opens on the outer cylindrical surface <NUM> in a direction opposite to the bottom <NUM>. The notch <NUM> is configured for receiving an intermediate portion <NUM> of the clamping rod <NUM>.

Upon assembly of a yarn-clamping device, a maintaining device <NUM> is mounted at each longitudinal end of the clamping rail <NUM>. A yarn-clamping device thus comprises two maintaining devices <NUM>, two retaining members <NUM> and two shuttles <NUM>. Axes X22 and X60 are aligned and superimposed, axes Y22 and Y60 are made parallel and axes Z22 and Z60 are made parallel.

Before inserting the clamping rod <NUM> into the clamping rail <NUM> of a yarn-clamping device <NUM>, the yarn layer L1 or L2 is drawn from the warp beam in order to extend along the front face <NUM> of this clamping rail <NUM>. Between the warp beam and the front face <NUM>, the yarns <NUM> of each yarn layer L1 or L2 are guided by one of two rollers <NUM>.

Upon installation of the clamping rod <NUM> into the yarn-clamping device <NUM>, its central portion <NUM> is inserted into the clamping volume V22 through the opening O22, with a translational movement parallel to axis Y22, as shown by arrow A1 on <FIG>. This translational movement A1 induces that the two intermediate portions <NUM> of the same clamping rod <NUM> are also inserted into the housings H26, in particular into the notches <NUM>, through the openings O26 by a translation along the axes Y60 of the two maintaining devices <NUM>, also represented by arrow A1 on <FIG>. Thus, each opening O26 is a passage-opening for the clamping rod <NUM>.

This supposes that each retaining member <NUM> is in a release position, oriented as shown in the upper portion of <FIG>, with its surfaces <NUM> and <NUM> parallel to the axis Y60.

As can be derived from <FIG>, independently of the positions of the retaining member <NUM> in the housing H26, the or each opening O26 extends further away from a plane containing axes X60 and Z60 than the opening O22 extends away from a plane containing axes X22 and Z22. In other words, the opening O22 corresponding to the clamping volume V22 is located, along the transverse direction Y22 or Y60, between the clamping volume V22 and the opening O26 corresponding to each housing H26.

In addition, the branch <NUM> of the retaining member <NUM> extends further away from the axis X76, toward the opening O26, than the volume V22 extends up to the opening O22.

In this position, the retaining member <NUM> does not hinder the passage for the clamping rod <NUM> out of the notch <NUM>.

Thus, when the clamping rod <NUM> is moved in the direction of arrows A1 on <FIG> and <FIG>, the planar surface <NUM> of its intermediate portions <NUM> starts sliding on the planar surface <NUM> of the two retaining members <NUM> before its central portion <NUM> enters the clamping volume V22, via the opening O22. Thus, the two planar surfaces <NUM> form guiding surfaces of the central portion <NUM> toward the clamping volume V22.

At the end of the translational movement represented by arrow A1, the clamping rod <NUM> is in an insertion position where the rod <NUM> may still pass through the opening O22, in an extraction movement, opposite to introduction movement of the clamping rod represented by arrows A1. In this insertion position, the planar surface <NUM> faces the internal surface <NUM>.

At this stage, the retaining member <NUM> of each maintaining device <NUM> is in a release position represented on top of <FIG>, where it does not block a movement of the corresponding intermediate portion <NUM> along axis Y60, in the direction of arrow A1 or in the opposite direction.

In this release position, which corresponds to the retracted position of the shuttle <NUM>, the rounded end <NUM> of the shuttle <NUM> cooperates with the retaining member <NUM>, by sliding contact with the outer cylindrical surface <NUM> of the retaining member <NUM>, and does not prevent any rotating movement of the retaining member <NUM> around its axis X76. The maintaining device <NUM> is in a release configuration.

When the clamping rod <NUM> is inserted into the clamping volume V22 and the housing H26 via the translation along the axes Y22 and Y60 represented by the arrows A1, its central portion <NUM> pushes the yarns <NUM> of the corresponding layer L1 or L2 toward the bottom of the clamping volume V22, through the opening O22.

Then, a torque can be applied on at least one end portion <NUM> of the clamping rod <NUM> in order to rotate this rod, in a clamping direction, around its longitudinal axis X24, within the clamping volume V22. A clamping direction can be defined as a rotation direction, which brings the clamping rod <NUM> relative to the clamping rail <NUM> from the insertion position, represented on top of <FIG> and <FIG>, successively to the intermediate position, represented in the middle of <FIG> and <FIG>, and to the clamping position, represented at the bottom of <FIG> and <FIG>. This clamping direction is a rotational direction around the axis X24, in the direction of arrows R2 on <FIG> and <FIG>.

The inner cylindrical surface <NUM> and the circular surface <NUM> cooperate for guiding the rotation movement of the clamping rod <NUM> in the clamping volume V22. This creates a regular tensioning of the yarns <NUM> along the yarn layer width. The internal surface <NUM> projects, at least partially, into a cylindrical volume whose diameter is equal to the maximum dimension of the clamping rod, i.e. equal to diameter D1, and which is delimited in the clamping volume V22 all around the rotation axis X24 of the clamping rod <NUM>.

This rotation in the clamping direction R2 of the clamping rod <NUM> induces a corresponding rotation of the retaining member <NUM> around the same axis with the same angular amplitude, also represented by arrows R2 on <FIG>, since the intermediate portion <NUM> and the retaining member <NUM> are coupled together in rotation around the axes X24 and X76, by cooperation of shapes between the surfaces <NUM> and <NUM>, on the one hand, <NUM> and <NUM>, on the other hand. Thus, the cylindrical surface <NUM> is secured in rotation with the clamping rod around axis X24. During this rotation in the clamping direction R2, the outer cylindrical surface <NUM> of the retaining member <NUM> slides on the rounded end <NUM> of the shuttle <NUM> and on the internal cylindrical surface <NUM>, with no possibility of movement in the transverse direction Y22. The maintaining device <NUM> is still in release configuration.

This brings the clamping rod to the second position represented in the middle of <FIG> and <FIG>. This position is an intermediate position for the clamping rod <NUM>, where the yarns <NUM> go through the clamping volume V22 but are not blocked within this clamping volume, insofar as they can slide with regard to the central portion <NUM>.

In this position, because of the non-circular profile of the clamping rod <NUM>, the maximum external dimension d24 of the cross-section of the central portion <NUM> of the clamping rod <NUM>, this dimension being parallel to the axis Z22, is larger than the distance d2 and smaller than the diameter D1. For example d24 is equal to <NUM>.

W22 denotes the width of the opening O22, which is measured parallel to the axis Z22, that is perpendicularly to the axis Y22. W22 is for example equal to <NUM>. Preferably W22 is between <NUM>% and <NUM>% of the diameter D1. W22 is substantially equal to the dimension d2.

According to an advantageous aspect of the invention, in the intermediate position of the clamping rod <NUM>, the portions 30a and 30b face the clamping rod <NUM> in the direction of arrow A1 along the transverse direction Y22. In this intermediate position, the external dimension d24 is strictly larger than the width W22 measured at the same level along the longitudinal axis X22 as external dimension d24. Thus the clamping rod <NUM> is locked within the clamping volume V22 all along its central portion <NUM>, insofar as it cannot be extracted from this volume through the opening O22 with only a transverse movement along axis Y22. In other words, a difference d3 = d3a+d3b between the maximum dimension d24 and the width W22 is sufficient to create on the clamping rail <NUM>, within the clamping volume V22, a retaining zone by cooperation of shapes between the clamping rod and the portions 30a, 30b for blocking the clamping rod <NUM> within this clamping volume. This retaining zone extends on the whole length of the longitudinal central portion <NUM> received in the clamping volume V22 and on both sides of the main plane P22, as shown by the two references d3a and d3b on <FIG>, which avoids bending of the clamping rod <NUM>, in particular when this length is more than <NUM> meters.

As visible at the bottom of <FIG>, in the clamping position, the clamping rod <NUM> cooperates only with the rubber profile <NUM> on one side of the main plane P22, with the yarns <NUM> in-between, whereas the clamping rod <NUM> cooperates only with the clamping rail <NUM> on the other side of the main plane P22, with the yarns <NUM> in-between. The circular surface <NUM> faces the internal surface <NUM>. The portions 30a, 30b and the circular surface <NUM> cooperate together in a form-fitting manner, with the yarns <NUM> in-between. The clamping rod <NUM> partially protrudes through the insertion/extraction opening O22 and out of the clamping rail <NUM>. In particular, as visible at the bottom of <FIG>, the clamping rod <NUM> protrudes out of the clamping rail <NUM> only beyond the portion of the front face <NUM> situated on the same side of the main plane P22 as the internal surface <NUM>, over a non-zero distance d5. The clamping rod <NUM> does not protrude out of the clamping rail <NUM> beyond the portion of the front face <NUM> situated on the other side of the main plane P22.

On the other hand, in this position, the second branch <NUM> of the retaining member <NUM> is interposed between the clamping rod <NUM> and the opening O26, so that it prevents the passage of the intermediate portion <NUM> of the clamping rod <NUM> out of the notch <NUM> and also holds the corresponding intermediate portion <NUM> within the housing H26. This position is thus a holding position for the retaining member <NUM>.

d4 denotes a distance, measured in the holding position of the retaining member <NUM> parallel to the axis Z60, between the free end <NUM> of its branch <NUM>, on the one hand, and an edge <NUM> of the main body portion defining the opening O26 next to the through hole <NUM>. This distance d4 is strictly smaller than the width W26, preferably less than <NUM>% of this width. For example d4 is equal to <NUM> and W26 is equal to <NUM>.

d24' denotes the maximum external dimension of the cross-section of the intermediate portion <NUM> parallel to the axis Z60 in the intermediate position of the clamping rod <NUM>, that is in the holding position of the retaining member <NUM>. This dimension d24' is preferably smaller than, or equal to, the maximum dimension d24. This dimension d24' is strictly larger than the distance d4, so that the clamping rod <NUM> is locked within the housing H26 by the retaining member <NUM>. In other words, the remaining width, also called "apparent width", of passage through the opening O26 for the intermediate portion <NUM> is reduced to the distance d4, which is smaller than the dimension d24'. This prevents extraction of the clamping rod <NUM> from the housing H26.

Due to the rotation of the retaining member <NUM>, the shuttle <NUM> does not bear anymore against the outer cylindrical surface <NUM>, so that its movement toward the housing H26 is no more limited by the retaining member <NUM>. Thus, the shuttle <NUM> is pushed by the spring <NUM> up to a contact between its collar <NUM> and the shoulder <NUM>, so that its rounded end <NUM> protrudes within the housing H26 in a blocking position. This occurs automatically, because of the action of the spring <NUM>, during the rotation of the retaining member <NUM> in the clamping direction of the arrow R2, without an action of an operator. The movement of the shuttle <NUM> from the retracted position to the blocking position, which is relative to the retaining member <NUM> and to the clamping rod <NUM>, occurs automatically when the clamping rod <NUM> performs its rotation movement from the insertion position to the intermediate position in the clamping direction. In this blocking position and for the clamping rod <NUM> in the intermediate position, the shuttle <NUM> is in contact with the retaining member <NUM> in a circumferential direction around axes X24 and X76.

In this configuration, the shuttle <NUM> forms an obstacle to the rotation of the retaining member <NUM> in the direction of arrow R3 on <FIG>, around axis X76. In other words, once it has reached the holding position, with the obstacle-forming shuttle <NUM> in blocking position, the retaining member <NUM> cannot go back to its release position by a rotation in a direction R3 opposite to the clamping direction R2, since this rotation movement is blocked by the obstacle-forming shuttle <NUM>. Hence, the shuttle can also be called an obstacle for the retaining member <NUM>. The maintaining device <NUM> is then in a holding configuration.

Because the retaining member <NUM> is coupled, in rotation around axes X24 and X76, with the clamping rod <NUM> by cooperation of shapes of surfaces <NUM>, <NUM>, <NUM> and <NUM>, the retaining member <NUM>, blocked by the obstacle formed by the shuttle <NUM>, prevents a rotation of the clamping rod <NUM> in the direction of arrow R3.

The retaining member <NUM> is used as an interface between the obstacle <NUM> and the portion <NUM> of the clamping rod <NUM>.

Even if it blocks the retaining member <NUM> in the direction of arrow R3, the obstacle <NUM> does not block the retaining member in the clamping direction R2 so that, in the holding configuration of the maintaining device <NUM>, if one continues exerting the above-mentioned torque in the direction of arrow R2, the clamping rod <NUM> can move from the intermediate position to the clamping position represented at the bottom of <FIG>, where the yarns <NUM> are pinched between its central portion <NUM> and the internal surface <NUM> of the rubber profile <NUM>. Actually, the shape and location of the rubber profile <NUM> is such that, when it is in the clamping position, a joining edge <NUM> between the surfaces <NUM> and <NUM> of the central portion <NUM> slightly penetrates the rubber profile <NUM> at the level of the internal surface <NUM>, with the yarns <NUM> in-between, which ensures a proper clamping of the yarns <NUM> within the clamping volume V22. The clamping rod <NUM> penetrates the internal surface <NUM> when the yarns <NUM> are pressed against the rubber profile <NUM> by the clamping profile <NUM>, which causes a local deformation of the rubber profile <NUM>.

Since clamping rod <NUM> is made of one piece, surfaces <NUM> and <NUM>, and edge <NUM> are made up of metal.

From the intermediate position to the clamping position, the obstacle-forming shuttle <NUM> does not move relative to the body <NUM> and the retaining member <NUM> has no transverse movement along the axis Y60.

In the clamping position of the clamping rod <NUM>, the rod is oriented around the axis X24 in such a way that its diameter D1 equals the maximum external dimension d24 of its central portion <NUM>, this dimension being parallel to axis Z22. Thus, in this clamping position, the ratio d24/W22 is strictly larger than <NUM>, where the dimension d24 and width W22 are measured at the same longitudinal level along the longitudinal axis X22, and the portions 30a and 30b of the inner cylindrical surface <NUM> together form a retaining zone for holding the clamping rod <NUM> within the clamping volume V22, as shown at the bottom of <FIG>.

In the clamping position, the retaining member <NUM> is in a third position, distinct from the holding position, because the clamping rod <NUM> and the retaining member <NUM> are coupled and move together in rotation between the intermediate position and the clamping position of the clamping rod <NUM>.

A tensioning device <NUM> belongs to the frame <NUM> and allows adjusting the position of the upper beam 16A along the posts <NUM>, as shown by double arrow A2 on <FIG> and <FIG>. In practice, one tensioning device <NUM> is mounted between each post <NUM> and the upper beam 16A. The direction of the adjusting movement of the upper beam 16A is a direction of approach/distance with respect to the lower beam 16B, this direction being perpendicular to the longitudinal directions of these beams. This direction is parallel to the axes Z22 of the clamping rails of the four yarn-tensioning devices <NUM>. Each tensioning device <NUM> includes a spindle <NUM> which is actually movable and connected, by a bracket <NUM>, to the upper beam 16A. A first spindle can be operated by the operator via a non-represented ratchet wrench and its rotational movement is transmitted to the other spindles, which form driven spindles, by one or several synchronization chains <NUM>.

On the other hand, the lower beam <NUM> is mounted on the posts <NUM> without any possibility of movement.

Thanks to the tensioning device <NUM>, it is possible to adjust a distance between the two clamping devices <NUM> of a pair of clamping devices, parallel to their axes Z22, thus to adjust the tension of the yarns of the first and second layers L1 and L2.

The yarn frame <NUM> is mounted on some posts <NUM> of the fixed structure <NUM> of the drawing-in machine <NUM> with possibility of a variable inclination with regard to this fixed structure. This is obtained by a system of articulated levers <NUM>, articulated on the posts <NUM>. Each lever <NUM> is associated with a gas spring <NUM>. The operator can thus prepare clamping and tensioning of the layers L1 and L2 when the yarn frame <NUM> is substantially horizontal, that is in a position of the yarn frame <NUM> where the openings O22 of the clamping rails <NUM> are oriented upwardly, facing the top in a vertical direction. Before starting the drawing-in process, the yarn frame is tilted back to a vertical drawing-in position represented on <FIG>, <FIG> and <FIG>.

Alternatively, the yarn frame <NUM> can be stationary with respect to the fixed structure <NUM>.

The relative movement of the drawing-in unit <NUM> with respect to the yarn frame <NUM> may result from the fact that the drawing in-unit is movable during the drawing-in process along a longitudinal axis X12 of the yarn frame <NUM>, whereas the yarn frame <NUM> remains stationary. Alternatively, the drawing-in unit is stationary and the yarn frame moves during the drawing-in process. One can make use of the teachings of <CIT> or <CIT>.

In the case represented on the figures where the drawing-in process is implemented with a single drawing-in unit <NUM> with yarns <NUM> taken from two warp layers L1 and L2, the lower beam <NUM> supports two clamping devices <NUM> and the upper beam <NUM> supports two other clamping devices, as explained here-above.

In case the drawing-in process takes place with yarns <NUM> taken from a single warp yarn layer, a single clamping device <NUM> can be mounted on each beam <NUM>.

In the drawing-in machine represented on the figures, the clamping rail <NUM> of each clamping device 20A2 and 20B2 of the second pair of clamping devices is movable along the corresponding beam that supports it, that is parallel to its longitudinal axis X22. With this respect, the clamping rail <NUM> is controlled by a dedicated adjusting device <NUM>. This adjusting device <NUM> includes a nut <NUM> in threaded engagement with a spindle <NUM> and guided by a rail <NUM> fastened to the main structure of the yarn frame <NUM>, in particular along axis X22. A bevel gear <NUM> driven by a crank handle <NUM> drives the rotation of the spindle <NUM>, thus the displacement of the nut <NUM> along a direction parallel to the axis X22 of the clamping rail, as represented by arrows A3 on the figures. On <FIG>, adjusting devices <NUM> are represented separated from the yarn frame <NUM>, and at a bigger scale. On <FIG>, the upper adjusting device <NUM> is represented in its configuration of use on the yarn frame <NUM>.

Each adjusting device <NUM> also includes a bolt <NUM> screwed in its nut <NUM>. The bolt <NUM> of the lower adjusting device <NUM> is not represented on <FIG>. Each bolt <NUM> is configured for being threaded in a threaded hole <NUM> located next to one end of the clamping rail <NUM> of a yarn-clamping device 20A2 or 20B2.

Each longitudinal end of the clamping rail <NUM> has a cut-out <NUM> for the reception of a retractable support <NUM>.

The cooperation of a bolt <NUM> and a threaded hole <NUM> allows transferring the translational movement of the nut <NUM> of an adjusting device <NUM> along its rail <NUM> to the clamping rail <NUM> of the associated yarn-clamping devices 20A2 or 20B2, which translate along its longitudinal axis X22.

As visible on <FIG>, an interface <NUM> is longitudinally interposed between the body <NUM> of the maintaining device <NUM> and the longitudinal end of the clamping rail <NUM> on the adjusting device longitudinal side. This interface <NUM> is fastened to the body <NUM> by the screws <NUM>. This interface is fastened to the nut <NUM> by a screw <NUM> which extends through the nut <NUM>, parallel to the bolt <NUM>, and which is engages in a threaded hole of the interface. Then, since the nut <NUM> is fixed at the end of the clamping rail <NUM> and with the interface <NUM>, the adjacent maintaining device <NUM> is indirectly secured to the clamping rails <NUM>.

In order to guide the movement of the clamping rail <NUM> of one of the yarn-clamping devices 20A2 and 20B2 relative to the associated beam <NUM>, each longitudinal beam <NUM> is provided with some guiding protrusions <NUM>, which are regularly distributed all along the length of the beam <NUM>. In fact, a set of two protrusions <NUM>, arranged to be located respectively above and under a clamping rail <NUM>, together form a guiding set <NUM>. As visible on <FIG>, the guiding sets <NUM> are distributed along the length of the beams <NUM>. The two protrusions <NUM> of a guiding set <NUM> are aligned along a direction parallel to the direction of the yarns <NUM> in a yarn layer L1 or L2, i.e. along a direction parallel to the axis Z22.

On the other hand, each clamping rail <NUM> is provided with two longitudinal grooves <NUM> configured for accommodating each a protrusion <NUM> and for sliding on this protrusion when the nut <NUM> moves along the rail <NUM>, if this clamping rail <NUM> is associated to an adjusting device <NUM>.

As visible on <FIG>, the two longitudinal grooves <NUM> of a rail have the same geometry, but are offset along the axis Y22.

Thanks to the longitudinal adjustment of the position of the yarn-clamping devices 20A1 and 20A2 of the second pair of yarn-clamping devices, it is possible to adjust the position of the yarns of the second yarn layer L2 with respect to the yarns of the first yarn layer L1, in the longitudinal direction of the beams <NUM>, at the level of a yarn separation zone YSZ located between the upper and lower beams <NUM>.

In addition, the upper yarn-clamping device 20A2 of the second pair of yarn-clamping devices is partially detachably mounted on the main structure of the yarn frame <NUM>, in particular on its upper beam <NUM>. In order to allow detachably mounting a clamping rail <NUM> on the yarn frame <NUM>, the walls of the two longitudinal grooves <NUM> are regularly interrupted along the clamping rail length, by cut-outs <NUM>. The distance between two adjacent cut-outs <NUM> along the axis X22 is the same as the distance between two adjacent guiding sets <NUM> along the longitudinal direction of the upper beam 16A. The length L186 of a cut-out measured parallel to axis X22 is larger than the length L180 of each protrusion <NUM> measured parallel to the longitudinal direction of the beam 16A.

This allows introducing the clamping rail <NUM> of the yarn-clamping devices 20A2 between the two protrusions <NUM> of the guiding sets <NUM>, along a direction parallel to axis Y22 and perpendicular to the longitudinal direction of the upper beam 16A, after having aligned the cut-outs <NUM> with these guiding sets <NUM>. This is represented by arrows A4 on <FIG> and <FIG>. It is then possible to slide the clamping rail <NUM> along its longitudinal axis X22, in order to engage the protrusions <NUM> into the longitudinal grooves <NUM>, thus blocking the clamping rail <NUM> on the upper beam <NUM> along axis Y22 and along axis Z22 via a bayonet movement. After this bayonet movement, the threaded hole <NUM> is aligned with the bolt <NUM> and the connection between a nut <NUM> and the clamping rail <NUM> can be performed via the bolt.

Preferably, before being brought into cooperation with the guiding sets <NUM>, the clamping rail <NUM> of the yarn-clamping device 20A2 is already fastened by screws <NUM> with a maintaining device <NUM> on its longitudinal side opposite to the threaded hole <NUM> and the adjusting device <NUM>. The interface <NUM> and the maintaining device <NUM> located on the longitudinal side of the adjusting device <NUM> are already fastened to the main structure of the yarn frame <NUM>.

The yarn-clamping devices 20A2 is partially detachably mounted on the longitudinal beam <NUM> of the yarn frame <NUM> insofar only one screw connection formed by the bolt <NUM> and the threaded hole <NUM> is required to mount the clamping rail <NUM> already equipped with one maintaining device <NUM> on the main structure of the yarn frame <NUM>.

As it is secured to the associated movable clamping rail <NUM> in the longitudinal direction, each maintaining device <NUM> of a yarn-clamping device 20A2 or 20B2 follows the translational movement of the clamping rail.

However, this is not compulsory. According to a non-represented alternative embodiment of the invention, these maintaining devices <NUM> can be stationary with regard to the yarn frame <NUM> and the intermediate portions <NUM> of the clamping rod <NUM> slide within these maintaining devices when the clamping rail <NUM> moves along its axis X22, between these maintaining devices.

In another non-represented alternative embodiment of the invention, when the yarns are pulled from the warp beam first on the lower beam 16B side and then on the upper beam 16A side, the detachable yarn-clamping device is the lower yarn-clamping device 20B2 mounted on the lower beam 16B.

In practice, in order to avoid, as much as possible, disturbance on the yarn distribution within a yarn layer L1 along the width of this yarn layer, the length L180 of each protrusion <NUM> along the longitudinal direction of the upper beam 16A is kept as small as possible. Indeed, as shown on <FIG> and <FIG>, the yarn separation at the level of the guiding sets <NUM> induces the creation of zones Zd of disturbance in the yarn distribution along the yarn width of the yarn layer L1. Keeping the length L180 small allows minoring these zones of disturbance.

Preferably, all clamping rails <NUM> of the four yarn-clamping devices <NUM> are extruded from the same die. They all have the same constant cross-section, in particular with two opposite longitudinal grooves <NUM>. In such a case, and as visible on <FIG> and <FIG>, some protrusions <NUM> located between two adjacent clamping rails <NUM> mounted on the same beam <NUM> are engaged in a first longitudinal groove <NUM> of a first clamping rail <NUM> which belongs to a first pair of yarn-clamping devices <NUM> and in a second longitudinal groove <NUM> of the adjacent clamping rail <NUM> of a yarn-clamping device <NUM> which belongs to the second pair of yarn-clamping devices <NUM>.

A clamping method for clamping the yarns <NUM> of a yarn layer L1 or L2 with a yarn-clamping device <NUM> is described here-below in connection with a single yarn clamping device <NUM>.

At the beginning of this process, the yarns <NUM> are drawn from the warp beam in order to cover the front face <NUM> of the clamping rail <NUM> in which the opening O22 is formed. In this configuration, the yarns <NUM> are located outside the clamping volume V22 of the yarn clamping device <NUM>.

At this stage, both maintaining devices <NUM> are in release configuration. For each retaining member <NUM>, the notch <NUM> opens toward the opening O26.

In the release position of the two retaining members <NUM>, the clamping rod <NUM> can be inserted into the clamping volume V22 and into the housings H26 by a translation parallel to axes Y22 and Y60, in the direction of arrows A1. Because of the direction of this translation, the clamping rod <NUM> pushes the yarns and deflects them into the clamping volume V22. If, during the insertion movement of the clamping rod <NUM>, the clamping rod <NUM> extends parallel to the axis X22, the action of the clamping rod <NUM> on the yarns <NUM> is the same over the width of yarn layer, parallel to the axis X24. During this translational movement, the planar surface <NUM> of the clamping rod <NUM> is oriented toward the rubber profile <NUM> and the planar surface <NUM> slides along the planar surface <NUM>, once the intermediate portion <NUM> of the clamping rod <NUM> crosses the opening O26.

The movement of the clamping rod <NUM> is guided toward the clamping volume V22 by the notch <NUM> formed in the retaining member <NUM>. In particular, during the translational movement represented by arrows A1, the planar surfaces <NUM> and <NUM> of the intermediate portions <NUM> of the clamping rod <NUM> slide along the planar surfaces <NUM> and <NUM> of the retaining member <NUM> and are guided toward the bottom <NUM> of the notch <NUM>. This guiding cooperation between parts <NUM> and <NUM> starts before the central portion <NUM> enters the clamping volume V22 since a distance between the opening O26 and the axis X60, measured along the axis Y60, is larger than a distance between the opening O22 and the axis X22, measured along the axis Y22. This movement in the direction of arrows A1 goes on up to the abutment of the surface <NUM> of the intermediate portion <NUM> against the bottom <NUM> of the two notches <NUM>.

The translational movement of the rod through the openings O22 and O26, in the direction of arrows A1, is possible since the distance d2 is slightly smaller than the width W22 and the distance d2' is smaller than the width W26. In other words, in the release position of the retaining member <NUM>, the clamping rod <NUM> can be fully aligned with the openings O22, O26 without any part of the yarn-clamping device <NUM> in-between.

The clamping rod <NUM> is then in an inserted position within the clamping rail <NUM>. From this position, the rod <NUM> can still be extracted from the clamping volume V22, if needed. The retaining member <NUM> is in its release position.

From the inserted position of the clamping rod <NUM>, the retaining member <NUM> is pushed by the rounded end <NUM> of the shuttle <NUM> which induces a slight displacement of the retaining member <NUM> within the housing H26, parallel to the axis Z60, in a direction away from the support plate <NUM>. The outer cylindrical surface <NUM> of the retaining member <NUM> comes into abutment against the portion of the internal cylindrical surface <NUM> opposite the through hole <NUM>. This allows guiding the rotation of the retaining member within the housing H26, by cooperation of surfaces <NUM> and <NUM>.

Axes X22, X24, X76 and X60 are then superimposed and form a common longitudinal axis X20 of the yarn-clamping device <NUM>. Each longitudinal beam <NUM> extends parallel to the common longitudinal axis X20.

The clamping rod <NUM> is then turned in the clamping direction represented by arrows R2 around the common central axis X20 by about <NUM>°. This brings the clamping rod <NUM> in its intermediate position represented in the middle part of <FIG> and <FIG>. This also brings the retaining member <NUM> into its holding position represented in the middle part of <FIG>. During this movement, the outer cylindrical surface <NUM> of the retaining member <NUM> slides in contact with the rounded end <NUM> of the shuttle <NUM> until the end <NUM> of its branch <NUM> is angularly shifted with regard to the obstacle formed by the shuttle <NUM>. In this position, the spring <NUM> pushes the obstacle formed by the shuttle <NUM> toward the housing H26 in such a way that this obstacle protrudes from the internal cylindrical surface of the housing H26 and its collar <NUM> comes into abutment against the shoulder <NUM>, as mentioned here above. Any rotational movement of the retaining member <NUM> in a direction, represented by arrow R3 and opposite to the clamping direction R2, is then prevented by the obstacle-forming shuttle <NUM> on which the end <NUM> abuts.

In the intermediate position of the clamping rod <NUM>, a clearance exists between the surface <NUM> and the surfaces <NUM>, <NUM>, this clearance allowing the yarns <NUM> to move along their extension direction, also within the clamping volume V22. It is then possible to distribute the yarns <NUM> along the axis X22 and/or to adjust tension the yarns, if needed, as explained here below.

In the holding position of the retaining member <NUM>, the intermediate portion <NUM> of the clamping rod <NUM> is blocked within the housing H26 by the retaining member because of the difference between the maximum dimension d24' and the remaining width d4 of the opening O26, as explained here-above.

When the retaining member <NUM> rotates in the clamping direction R2 between the holding position and the third position, which corresponds to the clamping position of the clamping rod <NUM>, it further reduces the remaining width of the passage for the clamping rod <NUM> out of the notch <NUM>, this width being is equal to zero in the third position of the retaining member <NUM>, as shown in the lower portion of <FIG>.

In the intermediate position of the clamping rod <NUM> and during the rotation from this intermediate position to the clamping position of the rod in the clamping direction R2, the yarns exert on the clamping rod <NUM> an effort which tends to push the clamping rod <NUM> out of the clamping volume V22, through the openings O22 and O26 and to rotate the clamping rod in a direction opposite to the clamping direction. Thanks to the retaining member <NUM>, the intermediate portions <NUM> are held within the housings H26, so that the central portion <NUM> is held within the clamping volume V22 in the intermediate position. In other words, the retaining member <NUM> opposes to the effort exerted by the yarns <NUM> on the clamping rod <NUM>.

In the intermediate position, the obstacle formed by the shuttle <NUM> does not prevent further rotation of the retaining member <NUM> in the clamping direction R2 toward the clamping position. It is thus possible to move the clamping rod <NUM> from the intermediate position to the clamping position, with the retaining member <NUM> driven by the clamping rod <NUM> between these two positions, by cooperation of shapes, as mentioned here above. For all positions relative to the clamping rail <NUM> reached by the clamping rod <NUM> during its rotational movement between the intermediate position and the clamping position in the clamping direction R2, the shuttle <NUM> is in its blocking position.

The third position corresponds to a rotation of the retaining member <NUM> on about <NUM>° around the common axis X20 with respect to the release position. Between the intermediate position and the clamping position of the clamping rod, the minimal distance between the clamping rod <NUM> and the internal surface <NUM> is reduced. In the clamping position, and as mentioned here above, this minimal distance is such that the yarns <NUM> are pressed between the clamping rod <NUM> and the internal surface <NUM> of the rubber profile <NUM>, which ensures a regular clamping of the yarns <NUM> along length of the clamping rail <NUM>. When clamped, the yarns <NUM> cannot move within the clamping volume V22 between the internal surface <NUM> and the clamping rod <NUM> if these yarns are subjected to normal efforts of the warp preparation process, of the drawing-in process for example.

In the clamping position, the planar surfaces <NUM>, <NUM>, <NUM> are globally parallel to the axis Z22, Z60 that is perpendicular to the transverse direction defined by axis Y22, Y60. The planar surface <NUM> faces the bottom of the clamping volume V22.

Between the intermediate position and the clamping position, when the clamping rod <NUM> rotates in the clamping direction R2, and in the clamping position, the difference d3, which equals to the sum of differences d3a and d3b represented in the center of <FIG>, between the maximum dimension d24 and the remaining width W22 is still sufficient to create, within the clamping volume V22, a retaining zone for blocking the clamping rod <NUM> within this volume.

For releasing the clamping action of the clamping rod <NUM> on the yarns <NUM>, the rod <NUM> is turned back, in the direction R3 opposite to the clamping direction, around the common axis X20. During this movement, the maintaining member <NUM> holds the corresponding intermediate portion <NUM> within the volume H26. When the intermediate position is reached again, as the maintaining device is still in holding configuration, the obstacle formed by the shuttle <NUM> prevents further rotation of the retaining member <NUM> in the direction of arrow R3. The operator can then push one of the two transverse pins <NUM>, or both of these pins, which protrude out of the slots <NUM> and <NUM>, against the elastic force of the spring <NUM> toward the support plate <NUM>. This brings back the shuttle <NUM> in retracted position. The obstacle retracts in the through hole <NUM>, the maintaining device is in release configuration and does not oppose any more a further rotation of the retaining member in the direction of arrow R3 opposite to the clamping direction of arrow R2. This allows the retaining member <NUM> to reach back its release position, with the outer cylindrical surface <NUM> of the retaining member <NUM> sliding on the rounded end <NUM> of the shuttle <NUM>.

For all positions relative to the clamping rail <NUM> reached by the clamping rod <NUM> during its rotational movement between the intermediate position and the clamping position in the clamping direction R2, the shuttle <NUM> is movable, from its blocking position to its retracted position, by the operator.

When the retaining member <NUM> is in its release position, the operator can release the transverse pin <NUM> and the rod <NUM>, which is back in its insertion position, can be extracted from the clamping volume V22 and from the two housings H26 by a translational movement through the openings O22 and O26, in a direction opposite to the one of arrows A1.

In an alternative unclamping process, the clamping rod <NUM> can be turned from its clamping position toward its inserted position in the clamping direction of arrows R2, with the maintaining device <NUM> still in holding configuration. In that case, the end <NUM> of the branch <NUM> comes into abutment against the rounded end <NUM> of the shuttle <NUM> and this end <NUM> pushes the shuttle inside the through hole <NUM>, against the elastic force of the spring <NUM>. This brings the outer cylindrical surface <NUM> into sliding contact with the rounded end <NUM>. The obstacle <NUM> is back in retracted position, the maintaining device <NUM> is in release configuration. Going on with the rotational movement of the clamping rod <NUM> in the clamping direction of arrows R2 allows the retaining member <NUM> reaching the release position, where the clamping rod <NUM>, which is back in its insertion position, can be extracted from the volume V22 and the housings H26, as in the first unclamping process.

In the second unclamping process, the clamping rod <NUM> and the retaining member <NUM> turn on <NUM>° between the insertion of the clamping rod <NUM> within the volume V22 and the housings H26, in the direction of arrows A1, and the extraction of the clamping rod from these volume and housings, in a direction opposite to arrows A1.

A method for clamping and tensioning the two yarn layers L1 and L2 with the yarn frame <NUM> is described here below.

First, the detachable yarn-clamping device 20A2 is partially removed from the upper beam 16A of the yarn frame <NUM> when the yarns <NUM> of the first layer L1 are pulled from the warp beam and laid before the front faces <NUM> of the clamping rails of the yarn-clamping devices 20A1 and 20B1 of the first pair. In this configuration, the yarns <NUM> extend along a yarn extension direction, which is vertical on <FIG> and <FIG>, and along which the yarn-clamping devices <NUM> are spaced from each other. These yarns <NUM> are drawn so that they extend at least up to the level of a brush roller <NUM>, which extends parallel to the beams <NUM>, under the lower beam 16B. The cooperation between the yarns and the brush roller <NUM> causes a friction on the yarns, which contributes to the yarn distribution along the axes X22 of these two yarn-clamping devices. Then, the retractable supports <NUM> of each of these two yarn-clamping devices <NUM> are brought to an extended position represented in dashed lines on <FIG> and a clamping rod <NUM> is laid on each of these supports in front of each clamping rail <NUM> of this pair of yarn-clamping devices, with the planar surface <NUM> oriented toward the other clamping rod <NUM> of this first pair of yarn-clamping devices. At this stage, each clamping rod <NUM> is located outside of the clamping volume V22.

Then the operator moves each clamping rod <NUM> into the associated volume V22 and housings H26, with a translational movement along direction of arrow A1, toward the inserted position of the clamping rod.

Then, the operator engages a wrench with the end portion <NUM> of each clamping rod <NUM> in order to bring each clamping rod <NUM> into its intermediate position. In this position of the two clamping rods <NUM>, the operator can distribute the yarns <NUM> of the first layer L1 along the longitudinal direction of the beams <NUM>. In this position of the clamping rods <NUM>, the yarns <NUM> of the first layer L1 do not have the same tension within the layer since they do not equally cooperate with the brush roller <NUM>. By spreading apart the beams 16A and 16B with respect to each other, via the tensioning device <NUM>, it is possible to level the yarn tension within the yarn layer L1. To sum up, the intermediate position enables to achieve a regular tension within the yarn layer L1.

Then, the operator can rotate the two clamping rods <NUM> to bring them into their clamping position. The clamping configuration of the yarns <NUM> of the first layer L1 is reached. The operator releases the tensioning device <NUM> in order to loosen tension within the first yarn layer L1.

In a variant, one of the two clamping rods <NUM> cooperating with the first layer L1 is first rotated in clamping position and then the operator uses the tensioning device <NUM> to achieve a regular tension within the yarn layer L1, before clamping the other of the two clamping rods <NUM>.

Then, the yarns <NUM> of the first yarn layer L1 lying at the longitudinal level of the guiding sets <NUM> are divided and arranged on either sides of each guiding set <NUM>, as shown by zones Zd on <FIG> and <FIG>.

A guiding rod <NUM> is mounted on the upper beam 16A, in order to force the yarns of the first layer L1 to follow a path close to the beam 16A and the yarn-clamping device 20A1 and to keep free a volume for the reception of the yarn-clamping device 20A2.

The yarns of the first warp layer are cut just below the lower yarn-clamping device 20B1 of the first pair and do not cooperate any more with the brush roller <NUM>.

Each nut <NUM> is brought to its middle position along the length of its adjusting spindle <NUM> and of its rail <NUM>. The yarn-clamping device 20B2 is moved accordingly along its common axis X20. The clamping rail <NUM> of the detachable yarn-clamping device 20A2 is then brought into cooperation with the guiding sets <NUM> and screwed with the nut <NUM> of the associated adjusting device <NUM>, by the bolt <NUM>, as explained here above.

The yarns <NUM> of the first layer L1 are thus interposed between the clamping rail <NUM> of the detachable yarn-clamping device 20A2 and the upper beam 16A, as visible on <FIG> and <FIG>.

The yarns <NUM> of the second warp layer L2 are pulled from the warp beam at the contact of the front faces <NUM> of both clamping rails <NUM> of the second pair of clamping devices <NUM> and up to the brush roller <NUM>.

As for the first layer, the retractable supports <NUM> are extended and reach the position represented in dashed lines on <FIG> and the clamping rods <NUM> are laid on these supports with the planar surface <NUM> oriented toward the other clamping rod <NUM> of this second pair of yarn-clamping devices, then pushed inside the two clamping rails <NUM> along the direction of the arrow A1 and rotated as explained here-above. When the clamping rods reach their intermediate position, the operator can distribute the yarns <NUM> of the second warp layer L2 along the longitudinal direction of the beams <NUM>, level the tension the yarns <NUM> along the width of the second warp layer L2 with the tensioning device <NUM> to a tension equivalent to the tension of yarn layer L1.

Then, the operator can rotate each clamping rod <NUM> of the yarn-clamping devices 20A2 and 20B2 in the rotating clamping direction, in order to reach the clamping position where the yarns <NUM> of the second warp layer L2 are clamped within the clamping rails <NUM> of the two yarn-clamping devices of the second pair.

Then the tensioning device <NUM> is used to spread apart the two beams <NUM>, so as to increase the tension of yarns in both warp yarn layers L1 and L2.

At the end of this warp layer preparation, the two warp layers extend substantially in the same plane between the upper clamping rails <NUM> and the lower clamping rails <NUM>, as visible on <FIG> and <FIG>.

The two warp yarn layers L1 and L2 are then in the configuration of <FIG>, in which they extend substantially in the same vertical plane, and the yarn frame <NUM> is vertical, ready for use of the drawing-in unit <NUM> in the drawing-in machine <NUM>.

With this respect, the drawing-in unit <NUM> can have a single separation device for the two layers L1 and L2, with a separation cord between the two layers L1 and L2, as disclosed in <CIT>. During the drawing-in process, in case the warp layer L1 and L2 have to be moved relative to one another along the longitudinal direction parallel to axis X20, each clamping rail <NUM> associated with an adjusting device <NUM> can be moved in the direction of arrows A3, that is parallel to the longitudinal direction of the beams <NUM>. This allows sliding the second yarn layer L2 with respect to the fixed structure <NUM> and the first yarn layer L1 parallel to the longitudinal direction of the beams <NUM>, in the direction of arrows A3. During this movement, the protrusions <NUM> guide the translation of the clamping rails <NUM> relative to the beams <NUM>.

If the yarn preparation occurs with the yarn frame in a tilted configuration, then there is no need for using the retractable supports <NUM>.

On <FIG> and <FIG>, the yarn frame <NUM> is represented when used with a single yarn layer L1 but is may also be used with two yarn layers as represented on <FIG>, <FIG>, <FIG> and <FIG>. Thus, the yarn frame <NUM> is versatile.

In the second to seventh embodiments of a yarn-clamping device according to the invention represented on <FIG>, the elements similar to the ones of the first embodiment bear the same references. Here after, mainly the differences with respect to the first embodiment are mentioned. If a reference is used in one of <FIG> without being mentioned in the following description, it designates the same part of the yarn-clamping device as the part with the same reference in the first embodiment.

In the second embodiment of <FIG>, the retaining member <NUM> has an L-shaped cross-section and the obstacle is formed by a rotating lever <NUM>.

The retaining member <NUM> defines a notch <NUM>, in the shape of a dihedron, with a bottom <NUM> and a branch <NUM> forming a planar surface <NUM>. The lever <NUM> is rotatable around a shaft <NUM> fixed with respect to the body <NUM> of the maintaining device <NUM>. The lever <NUM> is urged by a torsion spring <NUM> toward a blocking position represented at the bottom of <FIG>. The end <NUM> of the lever <NUM> is movable in a housing <NUM> defined between a main portion <NUM> of the body <NUM> and a bar <NUM> of the body <NUM> which delimits the opening O26 next to the lever <NUM>. This housing <NUM> is transverse to the longitudinal axis X24 of the clamping bar <NUM>, thus to the rotation axis X20 defined as in the first embodiment.

In its central portion <NUM> and in its intermediate portions <NUM>, the clamping rod <NUM> is hollow and has two outer planar surfaces <NUM> and <NUM> and two outer surfaces <NUM> and <NUM> in the form of an arc of a circle centered, in cross-section, on the longitudinal axis X24 of the clamping rod. A dimension d2, defined between, and perpendicular to, surfaces <NUM> and <NUM> is smaller than the width W22 of an opening O22 defined as in the first embodiment.

When the clamping rod <NUM> is inserted within the housing H26 of the maintaining device <NUM> through the opening O26 and within the clamping volume V22 through the opening O22, in the direction of arrow A1 on the top of <FIG>, the planar surface <NUM> slides on the planar surface <NUM> up to the point where the cylindrical surface <NUM> comes into contact with the bottom <NUM>. In this position, the outer cylindrical surface <NUM> of the retaining member <NUM> keeps the lever <NUM> in the retracted position away from its blocking position.

During rotation of the rod <NUM> in the housing H26 between its insertion position and its intermediate position, in the clamping direction represented by arrow R2, the end <NUM> of the branch <NUM> leaves the end <NUM> of the lever <NUM>, so that this lever automatically reaches its blocking position under the elastic force exerted by the spring <NUM>. This movement of the lever <NUM> between its retraced position and its blocking position occurs relative to the retaining member <NUM>, thus relative to the clamping rod <NUM>. In this blocking position of the lever <NUM>, its end <NUM> protrudes into the housing H26, as shown in the center of <FIG>. When the clamping rod <NUM> reaches its intermediate position represented in the center of <FIG>, the retaining member <NUM> is in a holding position where the end <NUM> abuts against the lever <NUM> in a circumferential direction around axis X60. In this position, the retaining member <NUM> is blocked by the lever <NUM>, against a rotation in a direction R3 opposite to the clamping direction R2. Hence, the lever <NUM> can also be called an obstacle for the retaining member <NUM>. The maintaining device <NUM> is then in holding configuration. In this intermediate position, the clamping rod <NUM> cooperates with the lever <NUM> via the retaining member <NUM> and is blocked by the retaining member <NUM> against a rotation in a direction R3 opposite to the clamping direction R2 around axis X60, by contact of the planar surface <NUM> with the planar surface <NUM>.

In this holding position of this second embodiment, the retaining member <NUM> does not limit the remaining width of the notch <NUM>. The clamping rod <NUM> is held in the clamping volume V22 and in the housing H76 by the difference d3 between, on the one hand, its maximum dimension d24 parallel to the axis Z60 and, on the other hand, the width W22 of the opening O22. This difference d3 creates a retaining zone by cooperation of shapes between the clamping rod <NUM> and the clamping rail <NUM>, because the maximum dimension d24 is strictly larger than the width W22.

The clamping rod <NUM> and the retaining member <NUM> can then be moved to a clamping position represented at the bottom of <FIG>, by further rotating the clamping rod <NUM> in the clamping direction R2. In this clamping position, the clamping rod <NUM> presses the yarns against an internal surface of the clamping volume V22 for their clamping.

During the movement of the clamping rod <NUM> between the insertion position and the clamping position, the outer cylindrical surface <NUM> of the retaining member <NUM> is in sliding movement against an internal cylindrical surface <NUM> of the body <NUM>.

According to an aspect of the invention that can be derived from <FIG>, in the clamping position of the clamping bar, the ratio d24/W22 is strictly larger than <NUM>, with dimension d24 and width W22 defined as in the first embodiment. The dimension d24 and width W22 are measured at the same longitudinal level along the rotation axis X20.

In the third embodiment of <FIG>, the maintaining device <NUM> comprises an obstacle formed by a sliding bolt <NUM> urged by a spring <NUM> toward the housing H26 but no retaining member comparable to retaining member <NUM> in the first and second embodiments. In this third embodiment, the obstacle <NUM> is secured directly within the body <NUM> with no possibility of rotation movement around the axis X60, since it is housed in a through hole <NUM> directly drilled in this body and extending in a direction parallel to an axis A90 transverse to the longitudinal axis X60 and to the axis Y60.

The clamping bar <NUM> has one outer planar surface <NUM> and one outer surface <NUM> in the form of an arc of a circle centered, in cross-section, on the longitudinal axis X24 of the clamping rod.

In this third embodiment, the maintaining device is made directly in the clamping rail <NUM>. In other word, the body <NUM> is made in a part of the clamping rail <NUM>, where the through hole <NUM> is drilled.

Here, the obstacle <NUM> is slidable with regard to the housing H26 and to the body <NUM>, and thus to the clamping rod <NUM>. In the example of <FIG>, the obstacle <NUM> is movable between a retracted position and a blocking position along a direction represented by arrows A5 and A6, which is perpendicular to the two axes X60 and X24 and to the direction of introduction of the clamping rod <NUM> within the housing H26, this direction being also represented by arrow A1 on <FIG>.

In the insertion position, and between the insertion position and the intermediate position when the clamping rod <NUM> rotates in the clamping direction R2, the obstacle <NUM> is in retracted position with its end <NUM> in contact with the outer planar surface 52of the clamping rod <NUM>. The maintaining device <NUM> is in release configuration.

A recess <NUM> is provided in each intermediate portion <NUM> of the clamping rod <NUM>, which is received in the clamping rail <NUM>, at the longitudinal level of the obstacle <NUM>. This recess receives the end <NUM> of the obstacle <NUM> in the blocking position of this obstacle, that is when the clamping rod <NUM> moves between its intermediate position and its clamping position in the clamping direction represented by the arrow R2, as in the first embodiment, and when the maintaining device <NUM> is in holding configuration. The obstacle <NUM> is automatically pushed toward the recess <NUM>, in the direction of the arrow A5, by the spring <NUM> mounted within the through hole <NUM> and immobilized therein, e.g. with a non-represented plate similar to plate support plate <NUM> of the first embodiment.

In this intermediate position, a first surface <NUM> delimiting the recess <NUM> cooperates with the obstacle <NUM> by direct abutment against the end <NUM> in the circumferential direction around axis X20 and in the direction of an arrow R3 opposite to the arrow R2. As the through hole <NUM> blocks the rotation of the obstacle <NUM> in the direction of arrow R3 on <FIG>, around axis X76, the clamping rod <NUM> cannot rotate in the rotating direction R3 opposite to the clamping direction R2. In the intermediate position and in the clamping position, the clamping rod <NUM> is retained in the clamping volume V22 by the difference d3 between, on the one hand, the maximum dimension d24 of the rod parallel to the axis Z60 and, on the other hand, the width W22 of the opening O22 at the same longitudinal level. Here openings O22 and O26 defined as in the first embodiment are identical.

During movement of the clamping rod <NUM> between its intermediate position and its clamping position, the obstacle <NUM> remains in its blocking position, in the recess <NUM> and in the through hole <NUM>, and does not move relative to the clamping rail <NUM>.

From the clamping position, if the clamping rod <NUM> is further rotated toward the insertion position in the clamping direction R2, a second surface <NUM> delimiting the recess <NUM> comes into contact with an inclined surface <NUM> of the end <NUM>, in order to push the obstacle <NUM> into its retracted position, in the direction of the arrow A6 visible at the bottom of <FIG>, against the action of the spring <NUM>. This brings the maintaining device <NUM> into its release configuration.

The fourth embodiment represented on <FIG> is particularly suited a yarn layer or some yarn layers of Denim yarns. Denim yarns are thicker than filament yarns for which the first three embodiments are designed. Denim yarns are drawn-in with a drawing-in machine represented on <FIG> and <FIG>, whose yarn frame <NUM> and drawing-in unit <NUM> are slightly different from the ones of the first embodiment.

In this fourth embodiment, no maintaining device is provided, in the meaning of maintaining device <NUM> of the first embodiment.

On <FIG>, the rubber profile <NUM> is located only above the main plane P22, whereas the clamping rail <NUM> delimits the clamping volume V22 on the other side of the main plane P22, that is under the main plane P22. The clamping direction of rotation R2 is counterclockwise on the figure, as in the second embodiment, whereas it is clockwise in the first and third embodiments.

The planar internal surface <NUM> of the rubber profile <NUM> is oriented toward the opening O22 and has an inclination angle α between <NUM>° and <NUM>°, preferably equal to about <NUM>°, with respect to a main plane P22 of the rail <NUM>. This angle α is also defined by the orientation of the bottom of the notch <NUM>, since the rubber profile has a rectangular cross section. In particular, as for the first embodiment, the internal surface <NUM> of the rubber profile <NUM> is also inclined with regard to the axis Z22 and parallel to the axis X22.

The section of the clamping rod <NUM> is the same along its whole length. It defines a circular surface <NUM> and a planar surface <NUM>, comparable to surfaces <NUM> and <NUM> of the first embodiment. These surfaces extend up to the two end portions <NUM> of the clamping rod, which are directly adjacent to the central portion <NUM>, without interposition of an intermediate portion <NUM>.

As shown in <FIG>, insertion of the clamping rod <NUM> into the clamping volume V22 occurs through the opening O22, as in the first embodiment, up to a position where its longitudinal axis X24 superposes with the longitudinal axis X22 of the clamping rail, on the rotation axis X20. Then, the clamping rod is rotated in the clamping direction R2, around the rotation axis, with a non-represented tool, which has an inner shape complementary to the cross section of the clamping rod <NUM>. This rotation in the clamping direction R2 goes on up to when the clamping rod reaches the intermediate position represented in the center of <FIG>, where a clearance C22 exists between the clamping rod <NUM> and the internal surface <NUM> of the rubber profile <NUM>. This clearance C22 allows the yarns to move within the clamping volume V22. For example, this clearance C22 has a non-zero width larger than the thickness of the yarns. Therefore, the operator can use this intermediate position to adjust the repartition of warp yarns <NUM> along the longitudinal axis X22, thus to make the yarn tension distribution more even along the clamping rail <NUM>. In the intermediate position, the planar surface <NUM> faces the internal surface <NUM>.

In this intermediate position and in the clamping position, the clamping rod cannot be fully extracted from the clamping volume V22 through the opening O22, for the same reasons as the ones mentioned for the first embodiment, in particular because the ratio d24/W22 is strictly larger than <NUM> and because of the retaining zone formed by the portions 30a and 30b of the inner cylindrical surface <NUM>. The dimension d24 and width W22 are measured at the same longitudinal level along the rotation axis X20.

Since no maintaining device is used in this embodiment, the clamping rod <NUM> is held in the intermediate position by the operator using the non-represented tool for exerting a torque around the rotation axis X20, against the reaction effort of the yarns, which tends to rotate the clamping rod in a direction opposite to the direction of rotation R2.

From the intermediate position represented in the center of <FIG>, a further rotation in the direction of rotation R2 allows reaching the clamping position represented at the bottom of <FIG>.

It is also possible to reach the clamping position from the insertion position with a rotation in a direction opposite to the direction of rotation R2. However, this does not allow reaching and using the intermediate position.

In this fourth embodiment, the parameters defined as for the first embodiment have the following values :.

With these values, the diameter D1 is strictly smaller than the diameter D30, which is well adapted to the case of Denim yarns, which are relatively thick.

The ratio D1/D30 is adapted to the thickness of the yarns to be clamped and is in a range between <NUM>,<NUM> and <NUM>.

The portion 30a starts on the edge of the opening O22 on the side of the main plane P22 opposite to the rubber profile <NUM>. The value of the angle α helps centering the portion 30a, in relation to the axis X22, with respect to the internal surface <NUM>. In particular, the portion 30a extends angularly, around the longitudinal axis X22 and over a first angular sector with an apex angle β, up to a transition step <NUM>. The value of angle β is between <NUM> and <NUM>°, preferably equal to <NUM>°. The side planar surface of the rubber profile <NUM> forming the internal surface <NUM> extends angularly, around the longitudinal axis X22 and over a second angular sector with an apex angle γ. The value of angle γ is between <NUM> and <NUM>°, preferably equal to <NUM>°. This second angular sector is opposite, with regard to the rotation axis X20, to the first angular sector of the portion 30a. In other words, the internal surface <NUM> faces the portion 30a, with the axis X22 in between. The transition step <NUM> is opposite to the opening O22 with respect to a plane formed by the axis Z22 and the longitudinal axis X22. In other words, the portion 30a goes, from the edge of the opening O22, up to beyond the longitudinal axis X22, along the transverse axis Y22. Thus, when the clamping rod <NUM> is in the clamping position, it cooperates with the portion 30a in both opposite transverse directions parallel to transverse axis Y22. This accurately positions the clamping rod <NUM> in the clamping volume V22 along transverse axis Y22.

The portion 30b starts on the edge of the opening O22 which is on the same side of the main plane P22 as the internal surface <NUM> and the portion 30b extends up to the internal surface <NUM>.

In the clamping position represented at the bottom of <FIG>, the clamping rod <NUM> partially protrudes out of the clamping volume V22. In particular, the clamping rod <NUM> partially protrudes out of the clamping rail <NUM>, beyond the two portions of the front face <NUM>, which are situated on both sides of the main plane P22, respectively over a non-zero distance d5. In other words, the clamping rod <NUM> partially protrudes through the opening O22 and out of the clamping rail <NUM>. This is due, in particular, to the geometry of the clamping rod <NUM> and of the clamping rail <NUM>. The effort exerted on the clamping rod <NUM> by the warp yarns <NUM> and by the rubber profile <NUM>, in a direction parallel to axis Y22, is oriented to the right on <FIG>. A reaction force exerted by the portions 30a and 30b of the inner cylindrical surface <NUM> of the rail <NUM> on the circular surface <NUM> of the clamping rod, is oriented to the left on <FIG> and defined by the geometry of surfaces <NUM> and <NUM>.

In practice, the ration d5/d2 is chosen between <NUM> and <NUM>, preferably equal to about <NUM>.

The yarn frame <NUM> of this fourth embodiment is represented on <FIG>. In the drawing in machine <NUM>, which incorporates this yarn frame <NUM>, the warp yarns <NUM> are pulled from the warp beam first on the side of the lower longitudinal beam 16B, then on the side of the upper longitudinal beam 16B. The lower yarn-clamping device 20B2 is detachable, as considered here above, in a non-represented embodiment, alternative to the first embodiment.

As in the first embodiment, the two longitudinal grooves <NUM> of a rail <NUM> have the same geometry and are offset along the axis Y22, by a non-zero distance d6. In this example, the value of d6 can be chosen between <NUM> and <NUM>, preferably equal to <NUM>. Thus, when two yarn-clamping devices are superposed and cooperate with a common guiding protrusion <NUM>, as yarn-clamping devices 20A1 and 20A2 on <FIG>, their rails <NUM> are offset by the distance d6. This implies that the yarn layers L1 and L2 are also offset by the same distance d6, as shown on <FIG> where the drawing-in unit <NUM> is represented by its envelope. This distance d6 facilitates identification and processing of the layers L1 and L2 in the drawing-in machine <NUM>.

Since grooves <NUM> are also offset in the first embodiment, the layers L1 and L2 are also offset in this embodiment, as can be derived from <FIG> and <FIG>.

Two yarn-clamping devices <NUM> are slidable, along directions parallel to the respective rotation axes X20 and longitudinal axes X22, namely the lower yarn-clamping device 20B2 and the upper yarn-clamping device 20A2 as in the first embodiment. The displacements of the yarn-clamping devices 20A2 and 20B2 are each controlled by one adjusting device <NUM>. The adjusting device associated to the lower slidable yarn-clamping device 20B2 is separated from the rest of the yarn frame <NUM> and shown on a larger scale on <FIG>. Each adjusting device <NUM> includes a hand wheel <NUM> which drives a parallel gear <NUM>, whereas a nut <NUM> is mounted on an output spindle of the parallel gear <NUM>, as in the first embodiment. A housing <NUM> is provided on the nut <NUM> for connecting the nut to a non-represented protrusion, e.g. a pin, of the corresponding clamping rail <NUM>. The housing <NUM> fulfills a function similar to the function of the bolt <NUM> of the first embodiment.

During the drawing-in process, the drawing-in unit <NUM> moves parallel to the longitudinal axes X22 of the clamping rails <NUM>. In order to assist this movement, the drawing-in unit <NUM> is equipped with a top guide roller <NUM> and a bottom guide roller <NUM>. The top guide roller <NUM> is mounted on, and secured to, the drawing-in unit <NUM> and freely rotatable around a rotation axis Z81, whereas the bottom guide roller <NUM> is also mounted on, and secured to, the drawing-in unit and freely rotatable around another rotation axis Z83. Advantageously the axes Z81 and Z83 are parallel to each other and to the yarns <NUM> in the yarn layers L1 and L2. During drawing-in, each roller <NUM> or <NUM> is in contact with, and rolls against, a portion of the circular surface <NUM> of a clamping rod <NUM>, which protrudes partially out of the clamping rail <NUM> of a yarn-clamping device <NUM> which belongs to the second pair of yarn clamping devices 20A2, 20B2. As shown on <FIG>, this allows guiding the longitudinal movement of the drawing-in unit <NUM> along the longitudinal axis X22 of each clamping rail <NUM> and positioning the drawing-in unit with respect to the yarn layers L1 and L2.

In a non-represented variant of the invention, only one roller <NUM> or <NUM> is provided for guiding the drawing-in unit parallel to the longitudinal axis X22 of a clamping rail <NUM>.

In the fifth embodiment represented on <FIG>, the internal surface <NUM> of the rubber profile is curved, in particular concave. The bottom of the notch <NUM> is also curved, in particular concave, with globally the same cross-section as the internal surface <NUM>.

Advantageously, the internal surface <NUM> as a cross-section in the form of an arc of a circle, with a diameter slightly smaller than the diameter of the adjacent portion 30b of the inner surface <NUM>. The internal surface <NUM> projects, at least partially, into a cylindrical volume whose diameter is equal to the maximum dimension of the clamping rod, i.e. equal to diameter D1, and which is delimited in the clamping volume V22 all around the rotation axis X24 of the clamping rod <NUM>.

The portion 30b of the inner surface <NUM> forms, together with the other portion 30a of this surface <NUM>, a retaining zone for blocking the clamping rod <NUM> within the clamping volume V22 in the clamping position of the clamping rod <NUM>. A retaining zone for blocking the clamping rod <NUM> within the clamping volume V22 is also formed by the inner surface <NUM> in the intermediate position and between the intermediate position and the clamping position when the clamping rod <NUM> is rotated in the clamping direction R2.

In such a case, the inclination angle α of the internal surface <NUM> is the mean inclination angle. Its value is between <NUM>° and <NUM>°, preferably equal to about <NUM>°.

In this case, the rotation angle between the insertion and intermediate positions preferably in the clamping direction R2 equals <NUM>° and the rotation angle between the intermediate and clamping positions in the clamping direction R2 preferably equals <NUM>°.

In the clamping position represented at the bottom of <FIG>, the part of the clamping rod <NUM> penetrating the internal surface <NUM> is a portion of the circular surface <NUM> instead of the edge <NUM>, as the previous embodiments. In this clamping position, the clamping rod <NUM> partially protrudes, through the opening O22, out of the clamping rail <NUM>. In particular, the clamping rod <NUM> partially protrudes out of the clamping volume V22 and beyond the two portions of the front face <NUM>, which are situated on both sides of the main plane P22, over a non-zero distance d5, as in the fourth embodiment.

As in the previous embodiments, in the intermediate and clamping positions represented in the middle and at the bottom of <FIG>, and between the intermediate and the clamping positions when the clamping rod <NUM> is rotated in the clamping direction R2, the ratio d24/W22 is strictly larger than <NUM> and a retaining zone of the clamping rod <NUM> is formed by the portions 30a and 30b of the inner cylindrical surface <NUM> for blocking the clamping rod <NUM> within the clamping volume V22. The dimension d24 and width W22 are measured at the same longitudinal level along the rotation axis X20.

In the sixth embodiment of <FIG>, the clamping rod <NUM> is hollow as in the second embodiment. The external cross-section of the clamping rod <NUM> defines a circular surface <NUM>, made of two portions 48a and 48b centered on the longitudinal axis X24, and two parallel and opposite planar surfaces 50a and 50b. The two portions 30a and 30b of the inner surface <NUM> of the clamping rail together form a retaining zone for blocking the clamping rod <NUM> within the clamping volume V22, at least when it is in the clamping position represented on <FIG>, where the maximal external dimension d24 of its cross section is strictly larger than the width W22 of the opening O22 of the clamping volume, these dimension and width being measured at the same longitudinal level along the rotation axis X20. The retaining zone of the clamping rail <NUM> is formed by the two cylindrical portions 30a and 30b. The circular surface <NUM> and the portions 30a, 30b cooperate in a form-fitting manner, with the yarns <NUM> in-between, in the clamping position of the clamping rod <NUM>.

In the seventh embodiment of <FIG>, the portion 30b of the inner surface <NUM> is cylindrical, with a cross section in the form of an arc of a circle centered on axis X24. The portion 30a does not have a cross section in the form of an arc of a circle. The portion 30a comprises several surfaces 30a1, 30a2 and 30a3. Surface 30a1 is a convex surface forming a transition between the edge of the opening O22 and a surface 30a2 perpendicular to axis Y22 and parallel to axes X22 and Z22. Surface 30a3 is a planar surface which is perpendicular to axis Z22 and parallel to axes X22 and Y22. The surface 30a1 is at least partially turned toward the bottom of the clamping volume V22 at the opposite of the opening O22 along the transverse axis Y22. The surfaces 30a1 and 30a3 cooperate with the clamping rod <NUM>, with the yarns in-between, in the clamping position represented on <FIG>. As in the other embodiments, the portion 30a also defines, together with the portion 30b, a retaining zone for blocking the clamping rod <NUM> within the clamping volume V22 in the clamping position of the rod. In particular, the surface 30a1 cooperates along the transverse direction Y22 with the circular surface <NUM> of the clamping rod <NUM>, with the yarns <NUM> in-between. In this clamping position, the portion 30b and the circular surface <NUM> cooperate together in a form-fitting manner, with the yarns <NUM> in-between. In this position, the ratio d24/W22 is strictly larger than <NUM>, with dimension d24 and width W22 defined as in the first embodiment. The dimension d24 and width W22 are measured at the same longitudinal level along the rotation axis X20.

In this embodiment, the clamping rail <NUM> is formed of two parts 22a and 22b secured together, e.g. by screws or by welding. These two parts cannot have a relative movement. As for all the other embodiments, the portions 30a and 30b have no possibility of relative movement with regard to the notch <NUM> housing the rubber profile <NUM> in the clamping rail <NUM>.

The yarn-clamping devices <NUM> of the second to seventh embodiments can be used instead of the ones of the first embodiment, in the drawing-in machine <NUM> and tying installation <NUM> of <FIG> and <FIG>.

In all these embodiments, the internal surface <NUM> of the single rubber profile is located on a single side of the main plane P22 and partly delimits the clamping volume V22, whereas the clamping rail fully delimits this clamping volume V22 on the other side of the main plane P22. In all these embodiments, the internal surface <NUM> shall be considered as the portion of surface of the rubber profile <NUM> that the clamping rod <NUM> penetrates during the clamping process. Thus, any additional rubber profiles and any additional surface of the rubber profile <NUM>, which are located in the clamping volume V22, which delimit this clamping volume but which have no cooperation with the clamping rod <NUM> during the clamping process and in the clamping position, do not form an internal surface but form a part of the clamping rail in the meaning of the present invention.

In a non-represented variant of the invention, only one yarn-clamping device or only some clamping devices of a yarn frame are according to the invention.

In another variant, especially if the yarn frame is for handling a single yarn layer, the yarn frame may include a single pair or yarn-clamping devices.

In another variant, a single yarn-clamping device can be used for clamping yarns of different overlapping yarn layers.

In a non-represented alternative embodiment, the lowermost and uppermost clamping devices 20A2 and 20B2 are fixed on the upper and lower beams <NUM> without possibility of translation along axis X22, whereas the other two clamping devices 20A1 and 20B1, that is the clamping devices handling the first layer L1, are movable along the beams <NUM> under the action of the adjusting devices <NUM>.

In a non-represented alternative embodiment, in the clamping position, the maximum external dimension d24 of the clamping rod cross section, measured parallel to the axis Z22, is not equal to diameter D1 of the clamping rod <NUM> and the planar surface <NUM> is not parallel to axis Z22.

In a non-represented alternative embodiment, in the clamping position, the retaining zone extends only on a single side of the main plane P22, preferably on the side of the main plane P22 that is opposite to the internal surface <NUM>.

The angles of <NUM>°, <NUM>°, <NUM>° and <NUM>° mentioned here above may vary. The first angle for the amplitude of rotation of the clamping rod <NUM> between the insertion position and the intermediate position in the clamping direction R2 may be between <NUM>° and <NUM>°, depending on the position of the internal surface <NUM> within the clamping volume V22. The second angle for the amplitude of rotation of the clamping rod <NUM> between the insertion position and the clamping position in the clamping direction R2 can be between <NUM>° and <NUM>°.

In another alternative embodiment, a yarn-clamping device <NUM> includes a single maintaining device <NUM> mounted at a first end of its clamping rail <NUM> for cooperating with an intermediate portion <NUM> located next to a first end of the of the clamping rod <NUM>. A rod holder is located at the second end of the clamping rail, for holding a second end of the clamping rod opposite to the intermediate portion with regard to the clamping rail. In that case, the second end of the clamping rod is inserted first in the rod holder, then the clamping rod is tilted so that its central portion enters the clamping volume and its intermediate portion enters the housing of the maintaining device. During this insertion of the clamping rod, the rod does not have a purely translational movement and is inclined relative to the longitudinal axis of the clamping rail.

In another variant, the body <NUM> is provided with an indexing pin protruding in the housing H26 and configured to engage in a circumferential limited recess provided on the outer cylindrical surface <NUM> of the retaining member <NUM>, in order to allow movement of the retaining member <NUM> only within the angular range delimited between the release position and the third position reached when the clamping rod rotates in the clamping direction between its insertion position and its clamping position. A rotation on <NUM>° is, in that case, not possible for the retaining member <NUM>. Furthermore an insertion of the clamping rod <NUM> in an insertion position where the planar surface <NUM> of the clamping rod <NUM> doesn't face the internal surface <NUM> is impossible in that case.

In another variant, the translation direction A90 of a slidable obstacle forming part <NUM> is not parallel to the axis Z20 but, for example, inclined with regard to axes Z60 and Y60.

In an alternative embodiment, the spring <NUM> is omitted. In that case, the obstacle can be weighted so that it is movable from its retracted position to its blocking position and maintained in blocking position due to gravity. In this alternative embodiment, of the maintaining device and if the maintaining device is made directly in the clamping rail <NUM> as described in the third embodiment, the maintaining device may comprise only an obstacle.

In another variant, the clamping rod is made up of different longitudinal portions of different cross-sections, hollow or not hollow, assembled together.

In all embodiments, in the intermediate position and in the clamping position of the clamping rod <NUM>, and when the clamping rod <NUM> rotates in the clamping direction R2 between the intermediate position and the clamping position, the clamping rod <NUM> cooperates along the transverse direction Y22 with the inner surface <NUM> by abutment against the inner surface <NUM> in the transverse direction Y22 opposite to the translational movement A1, with the yarns <NUM> in-between. The clamping rail <NUM> thus forms a retaining zone for blocking the clamping rod <NUM> within the clamping volume V22 such that the clamping rod <NUM> cannot be fully extracted from the clamping volume V22 through the opening O22 with only a transverse movement opposite to translational movement A1 at least in the clamping position. This cooperation between the clamping rod <NUM> and the inner surface <NUM> does not prevent rotation of the clamping rod <NUM> within the clamping volume V22 around rotation axis X20 if the operator rotates the clamping rod <NUM>. In the clamping position, the retaining zone blocks the clamping rod <NUM> within the clamping volume V22 in a position in which the clamping rod <NUM> protrudes out of the clamping rail <NUM> through the opening O22, as for the fourth, fifth and seventh embodiments, or doesn't protrude.

In all embodiments, thanks to the orientation of the internal surface <NUM> toward the opening O22, when the clamping rod <NUM> penetrates the internal surface <NUM>, the rubber profile <NUM> creates, on the clamping rod <NUM>, an elastic force toward the opening O22 along the transverse axis Y22. Because the internal surface <NUM> is inclined with an angle α between <NUM>° and <NUM>° with regard to the main plane P22, when the clamping rod <NUM> penetrates the internal surface <NUM>, the rubber profile <NUM> also creates, on the clamping rod <NUM>, an elastic force along axis Z22 in the direction of the inner surface of the clamping rail <NUM> that delimits the clamping volume V22 on the side of the main plane P22 opposite to the internal surface <NUM>.

As shown on <FIG>, yarn-clamping devices <NUM> according to the invention and a yarn frame <NUM> according to the invention can also be used in a warp tying installation <NUM> where two pairs of yarn-clamping devices <NUM> are mounted one above the other along the axis Z22 of a yarn frame <NUM> in a tying configuration. Each pair pairs of yarn-clamping devices <NUM> is dedicated to one warp layer. The yarn frame <NUM> is configured for guiding the translation of a tying unit <NUM>' along its longitudinal axis X12. The two pairs of yarn-clamping devices <NUM> are movable relative to one another along the longitudinal axis X12, as known for example from <CIT>, for relative movement of the two layers, these layers extending in two parallel and spaced planes.

The frame <NUM> can be movable and equipped with rollers <NUM> as shown on <FIG>, or stationary in a variant.

Claim 1:
A yarn-clamping device (<NUM>) for clamping yarns (<NUM>) of a yarn layer (L1, L2), this device including
- a clamping rail (<NUM>), which delimits a clamping volume (V22) extending along a longitudinal axis (X22),
- a clamping rod (<NUM>), configured to be inserted into the clamping volume through an insertion/extraction opening (O22) of the clamping rail and in a direction (Y22) transverse to the longitudinal axis, a longitudinal portion (<NUM>) of the clamping rod received in the clamping volume having a non-circular cross-section, the clamping rod (<NUM>) having a clamping rotation movement relative to the clamping rail (<NUM>), in a clamping direction (R2), within the clamping volume and around a rotation axis (X20) parallel to the longitudinal axis of the clamping rail,
∘ from an insertion position, where a first external dimension (d2) of the clamping rod cross-section, parallel to a width (W22) of the insertion/extraction opening (O22), is smaller that this width, so that the rod (<NUM>) can pass through the insertion/extraction opening (O22),
∘ to a clamping position, where the clamping rod clamps the yarns located in the clamping volume against an internal surface (<NUM>) located inside the clamping rail,
characterized in that
- with regard to a main plane (P22) of the clamping volume (V22) containing the rotation axis (X20) and crossing the insertion/extraction opening (O22) in the middle of this opening, one side of the clamping volume (V22) is delimited by the clamping rail (<NUM>) and the other side of the clamping volume is partially delimited by an internal surface (<NUM>) which belongs to a rubber profile (<NUM>) housed in the clamping rail (<NUM>);
- when the clamping rod (<NUM>) is in the clamping position, the clamping rod penetrates the internal surface (<NUM>) of the rubber profile (<NUM>), with the yarns (<NUM>) in-between; and
- when the clamping rod is in the clamping position, a maximum external dimension (d24, D1) of the clamping rod cross section, parallel to the width (W22) of the insertion/extraction opening (O22), is strictly larger than the width of the insertion/extraction opening, the maximum external dimension (d24, D1) of the clamping rod cross section and the width (W22) of the insertion/extraction opening being measured at the same longitudinal level, along the rotation axis (X20).