KR20000052550A - method for winding a fiber element having different longitudinal portions - Google Patents

Abstract

PURPOSE: A method for winding fiber elements having different longitudinal parts is provided to wind the fiber elements by respectively coupling an individual winding pitch to the different longitudinal parts, different from the pitches coupled to other parts adjacent to the different longitudinal parts, thereby rapidly and automatically unwinding the fiber elements without interruption. CONSTITUTION: A method for winding fiber elements(2) having different longitudinal parts includes the steps of drawing the fiber elements from a preform, and forming two longitudinal parts(Pi) having different characteristics, winding the two longitudinal parts on a supporting die(16), and coupling individual winding pitch values(pi) different each other to the respective longitudinal parts.

Description

Method for winding a fiber element having different longitudinal portions}

The present invention relates to a method of winding a fiber element having another longitudinal portion, and more particularly, to a method of winding a fiber element having another longitudinal portion to the reel at the end of the drawing process of the fiber.

For the purposes of the present invention, "fiber element" is understood to mean an optical fiber, wherein the optical fiber is suitably provided with a surface coating and other coatings.

As is well known in the art, optical fibers are produced in special drawing towers which come from preforms prepared in advance. In practice, the preform is fed to the furnace in a vertical direction to obtain casting of the molten material. The molten material is then drawn and cooled to obtain an optical fiber with the desired properties. These properties are obtained by properly fitting the coefficients of the drawing process, ie the furnace temperature, the speed of the fiber drawing and all other coefficients (described in detail below). At the end of the drawing process, the optical fiber is wound on a storage reel, which is then released from the storage reel when used to perform the test or to rewind to another reel.

In general, the drawing process is carried out over the entire process under the same process conditions, i.e. without changing the process coefficients. In such cases, the fibers are drawn from a single preform and are generally homogeneous and single along the entire length. At the end of the production process, the fibers are wound on a storage reel in a cylindrical spiral at constant pitch without interruption. For the purposes of the present invention, "winding pitch" means the distance between two successive intersections of a thread having the same parent point of the cylinder on which the helix lies. Threaded windings with a constant pitch are obtained by moving the reels axially so that the reels perform crossover movement at a constant speed, or by moving the member feeding the fiber to perform a similar movement.

Known drawing towers allow recent hundreds of kilometers of optical fiber to be obtained from a single preform with recent technological advances. As technology advances in the future, even longer fibers can be obtained in a single process. In view of the high yields already available today in the drawing process, fibers comprising longitudinal sections having different chemical / physical properties, for example, different nucleus and / or sheath diameters, different internal tensions, etc., are produced from a single preform. It is necessary or advantageous to form. The physical changes can be obtained by changing one or more characteristic process coefficients during the fiber drawing process.

For example, it may be beneficial to form a fiber comprising two or more longitudinal portions having substantially the same basic properties but having one or more optical, geometric or mechanical properties. A first example is presented by M. Ohashi in the April 1990 IEICE Bulletin E 73 Volume 4 Japanese NTT "Dispersion-adjusted single mode fiber by the VAD method". In this document, several kilometers of fiber parts are used to study the sensitivity of single mode optical fibers with low dispersion of 1.5 to 1.6 μm for micro-bending, which fibers are made from a single preform and only zero- They differ in terms of zero-chromatic-dispersion wavelengths.

The following example relates to the study of the phenomenon of mode dispersion ("polarization mode dispersion" or PMD) due to polarization. As is known, the phenomenon is affected by the photoelastic effect occurring in the fiber, which depends on the structural properties associated with the tension the fiber receives during the drawing process. Therefore, it is advantageous to have a usable fiber part with the same physical / chemical properties and different internal tensions for this kind of study.

U. S. Patent No. 5,400, 422 discloses a technique for forming a series of Bragg gratings that vary in pitch during the actual fiber drawing process in optical fibers. The gratings are formed by exposing the fiber to ultraviolet radiation pulses using interferometer type optical technology. The gratings are formed at a distance from each other along the fiber. Therefore, even in this case, fiber portions having different characteristics are formed by changing the operating conditions of the process during the drawing process.

In another example, it may be necessary to produce a local change in the properties of the drawn fiber, ie a change affecting only a small portion of the fiber. This type of situation is described in US Pat. No. 4,163,370, where the ends of large diameter fibers are formed to improve the performance of the fibers in terms of mode dispersion.

Applicants note that if it is necessary to form a fiber comprising different longitudinal sections, winding the fiber to the reel with a constant pitch without interruption is not very beneficial since the other parts of the wound fiber are not distinguished from each other afterwards. Paid. One way to solve this problem is to stop the winding process and hence the drawing process whenever a given fiber part is fully wound in order to be able to cut the fiber at the end of the part and replace the reel with the part replaced by an empty reel. It is to let. At this point, the winding process (and drawing process) can be started again and the next fiber section is wound on a new reel. However, the need to interrupt the drawing process each time leads to certain obstacles such as loss of time, waste of molten material from the preform and possible changes in the drawing conditions, for example, changes in the process's characteristic coefficients due to temporary changes. .

Alternatively, if the fiber is to be wound completely on the same reel, instead of cutting the end of the fiber for each of the wound portions, an indicator may be applied at a certain point on the individual portion, whereby each of the portions is then defined. The operation can be performed without interruption of the drawing process, as described in US Patent No. 5,400,422, which is already cited. However, the use of indicators to define other fiber segments is unreliable because at normal fiber unwinding speeds one may accidentally miss one or more of the indicators. Moreover, such techniques generally require an operator to define the indicator during the unwinding of the fiber.

Applicant, in the case of fibers comprising different longitudinal sections, if the fibers are wound by joining each of the sections with a separate winding pitch that is different from the winding pitch coupled to the adjacent sections, then the part of the part after We found that definitions can be done quickly, automatically and with very little error probability. Applicants particularly propose a winding method which can be carried out without interruption, thereby avoiding the above mentioned obstacles.

Applicants have also found that it is desirable to modulate the winding pitch with a periodic function in order to at least reduce the errors that can occur in defining the various fiber parts during the unwinding of the fiber. The change in the winding pitch is preferably carried out by modulating the axial movement speed of the reel during the winding, in the same law. If the fiber was wound in this manner, subsequent definition of another fiber portion while unwinding the fiber from the reel can be performed by detecting a change in the winding pitch in accordance with the present invention.

According to a first aspect, the invention relates to a method of winding a fiber element on a support, the fiber element comprising at least two longitudinal sections with different properties, the method comprising the fiber element on the support. And supplying the respective winding count values different from the values coupled to the adjacent portions to the respective portions. In particular, the step of coupling individual winding count values to each of the portions includes coupling individual winding pitches to the respective portions.

In particular, the step of coupling individual winding pitches to each of the portions includes coupling individual functions for modulation of the winding pitch to each of the portions.

Advantageously, coupling the respective functions for modulating the winding pitch to each of the portions comprises combining individual frequencies for the modulation of the winding pitch to each of the portions, wherein the modulation frequency is a separate period. Define the main frequency of the modulation function.

In particular, the step of coupling the individual winding pitches to each of the portions includes moving the supports in a predetermined direction at a speed correlated with the winding pitches, which is performed simultaneously with the step of feeding the fiber element to the supports. do.

The step of feeding the fiber element to the support includes guiding the fiber element towards the support by means of a feed member, which, by way of alternative to the method described above, engages individual winding pitches to the respective portions. The step of moving comprises the step of moving the supply member in a predetermined direction at a speed correlated with the winding pitch, carried out simultaneously with the guiding step.

Advantageously, said step of supplying said fiber element to said support is associated with a starting instant and an end instant, wherein the time between said starting and end points is coupled to said individual parts. Measuring an individual time interval between the start and end time points.

Preferably, the fiber element is an optical fiber, and supplying the fiber element to the support is performed simultaneously with producing the optical fiber, wherein the production step includes drawing the optical fiber from the preform.

More preferably the production step comprises measuring a process variable, which is performed during the drawing step, and signaling an individual warning condition indicating the presence of a defective fiber part if one of the variables exceeds a predetermined threshold. And coupling the individual values of the winding coefficients to each of the portions comprises combining the individual values of the winding coefficients to the defective fiber part.

According to a further aspect, the present invention relates to a method for distinguishing different longitudinal parts of a fiber element wound on a support according to the above mentioned method, which parts are combined with the individual winding pitch, Features include:

-Unwinding the fiber element from the support; And

During the unwinding step, detecting a change in winding pitch;

In particular, detecting the change in the winding pitch includes:

Repeatedly measuring the coefficients correlated to the winding pitch during the solving step to obtain a continuous value of the coefficients; And

Detecting a change in the count value.

Preferably, the method for distinguishing different longitudinal portions also comprises:

Comparing said respective obtained value of said coefficient with a stored series of values, wherein said stored values are combined with one of said parts; And

Based on the comparison, defining a longitudinal portion combined with the obtained value.

Preferably, the step of detecting a change in the count value is:

Storing the obtained value;

Comparing the continuous value of the coefficient with the stored value; And

If the continuous value differs from the stored value during the comparing step, stopping the solving step.

Advantageously, said step of measuring said coefficient comprises detecting a distance between an actual point at which a fiber element intersects a region and a predetermined intersection of said region.

Alternatively, the step of measuring the coefficients comprises detecting an angle between the direction of the fiber element unwinding from the support and the predetermined direction.

According to a further aspect, the present invention relates to a device for winding a fiber element on a support, the fiber element comprising at least two longitudinal sections with different properties, the device comprising:

A supply member for supplying the fiber element to the support; And

A moving device for moving one of the support and the supply member along a predetermined axis at a predetermined moving speed to obtain a predetermined winding pitch,

And each unit has a unit for controlling the moving device, which is designed to control the moving speed to engage a predetermined winding pitch different from the winding pitch associated with the adjacent part.

Preferably, at least one said winding pitch is modulated with a periodic function.

Preferably, the fiber element is an optical fiber.

According to a further aspect, the present invention relates to a mechanism for distinguishing different longitudinal portions of a fiber element wound on a support, each of which has an individual winding pitch associated therewith, the instrument comprising:

An apparatus for unwinding the fiber from the support;

A sensor device designed to iteratively measure coefficients correlated with said winding pitch and generate a signal indicative of said coefficients; And

A process unit designed to receive the signal and to detect a change in the coefficient based on the signal.

In particular, the process unit is:

A comparison lower unit for comparing the continuous values of the coefficients; And

If the continuous values are different from each other, a signal subunit is included to signal the presence of a new portion.

Preferably, the sensor device is an optical device having a sensitive area and a reference point on the sensitive area and designed to detect a distance between the point of intersection of the fiber element and the sensitive area and the reference point. .

Alternatively, the sensor device is designed to detect an angle between the direction of unwinding the fiber element from the support and the predetermined direction.

According to a further aspect, the present invention relates to a method of producing a fiber element, the method comprising drawing the fiber element from a preform and forming the fiber element into two longitudinal portions having different properties It comprises a, characterized in that it comprises the step of coupling the respective winding pitch to each of the two longitudinal portions and winding the two longitudinal portions in the support.

According to a final aspect, the invention relates to an assembly for the production of a fiber element, said assembly comprising a production apparatus designed to produce a fiber element comprising at least two longitudinal parts having different properties, said fiber And a winding mechanism designed to receive an element from the production tool, couple a separate winding pitch to each of the parts, and wind the fiber element on a support.

In particular, the winding mechanism is:

A supply member for supplying the fiber element to the support in a predetermined supply direction; And

An axial movement device for moving one of said support and said supply member in a predetermined direction and at an axial speed correlated with a winding pitch coupled to said portions with respect to each of said portions.

Preferably, the winding mechanism comprises a control unit connected to the axial movement device for controlling the axial speed.

Preferably, the production apparatus comprises a sensor device connected to the control unit, each of which is designed to detect individual process variables.

Preferably, the assembly also includes a mechanism for distinguishing other longitudinal portions of the fiber element wound on the support, the discriminating mechanism:

A release device designed to release the fiber element from the support; And

A detection device for detecting a change in the winding pitch, while unwinding the fiber element.

In particular, the detection device is:

A sensor device designed to generate a signal correlated with the winding pitch; And

A processing unit designed to receive the signal and to obtain a value representing the winding pitch from the signal.

In particular, the sensor device is an optical sensor designed to intersect the optical fiber.

Preferably the fiber element is an optical fiber and the production apparatus is a drawing tower.

Further details of the invention can be seen from the following description with reference to the accompanying drawings, listed below:

1 shows a tower for drawing an optical fiber formed according to the present invention;

2 shows a mechanism for unwinding a fiber from a reel according to the method of the present invention;

3 shows a variation of the mechanism of FIG. 2 with some portions removed for clarity;

4 shows a reel in which the optical fiber is wound according to the method of the present invention, in a simplified and simplified form;

5 shows a graph of two periodic functions used to modulate the winding pitch of a fiber, in accordance with the method of the present invention;

6 is a flowchart relating to the specific steps of the method according to the invention;

7 is a flow chart of further steps according to the present invention.

1 shows a drawing tower 1 designed to carry out the drawing of an optical fiber 2 from a preform 3 prepared in advance. The drawing tower 1 comprises a plurality of parts which are generally aligned in the vertical drawing direction (from which the word 'tower' emerges). The selection of the vertical direction for carrying out the main steps of the drawing process arises from the necessity of utilizing gravity to obtain a mold of molten material from which the fiber 2 can be drawn.

More specifically, the tower 1 draws an apparatus 4 for supporting and feeding the preform, a furnace 5 for carrying out the controlled melting of the preform 3, and the fibers 2 from the preform 3. And a drawing device 6 for winding and a device 7 for winding the fibers.

The furnace 5 can be of any type designed for controlled melting of the preform. Examples of furnaces that can be used in tower 1 are described in US Pat. Nos. 4,969,941 and 5,114,338. The furnace 5 may be provided with a signal sensor (not shown) designed to generate a signal indicative of the temperature in the furnace. The furnace temperature is a process coefficient that can be changed during the drawing process to change the properties of the fiber 2, for example to change the tension of the fiber 2.

Preferably, at the outlet of the furnace 5 there is a first diameter sensor 8, for example an optical sensor of interferometric type, which sensor generates a signal indicative of the diameter of the uncoated fiber 2. It is designed. Preferably, the first diameter sensor 8 also performs the function of a surface defect detector to detect defects in the fiber particles, for example defects such as bubbles or inclusions. The first diameter sensor 8 is, for example, CERSA (CERSA, Park Expobat 53, Plan de Campagne, F13825) in France, Cedex, Cabrie, F13825, Fland de Campagne, Park Expobart 53 , Cabries, Cedex, France) may be a sensor of the LIS-G type. This type of sensor is especially designed to generate a first signal proportional to the difference between the detected diameter value and the predetermined diameter value and a second signal indicating the presence of any surface defect.

The cooling device 9 is located below the furnace 5 and the diameter sensor 8 and may be of a type having, for example, a cooling cavity through which a cooling gas stream passes. The cooling device is arranged axially with respect to the drawing direction, so that the fibers 2 can pass through the furnace 5. The device 9 may be of the type described, for example, in US Pat. No. 5,314,515 and US Pat. No. 4,514,205. The cooling device 9 may have a temperature sensor (not shown) designed to indicate the temperature in the cooling cavity. Since the speed at which the optical fiber is drawn is usually relatively high, the cooling device 9 must allow rapid cooling of the fiber 2 to a temperature suitable for subsequent processing steps, in particular the surface coating described below. In order to change the characteristic of the fiber 2, the temperature in a cooling cavity is a processing coefficient which can be changed suitably by changing a cooling gas flow, for example.

The first and second coating devices 10, 11 positioned below the cooling device 9 in the vertical drawing direction are provided with a first protective coating on the fiber and an agent that overlaps the first protective coating when the fiber 2 passes. It is designed to deposit two protective coatings respectively. Each coating device 10, 11 hardens the resin to provide a firm coating, in particular for individual attachment units 10a, 11a designed to attach a predetermined amount of resin onto the fibers and, for example, a UV-lamp oven. To include individual curing units 10b and 11b. The amount of resin attached to each attachment unit 10a, 11a and the temperature of each curing unit 10b, 11b are coefficients that can change during the drawing process to produce a fiber portion having a different coating. Coating apparatus 10, 11 may be of the type described, for example, in US Pat. No. 5,366,527, and may be of a different number than indicated, based on the number of protective coatings to be formed on fiber 2.

The outlets of the first and second coating devices 10, 11 are each provided with a signal representing the diameter of the fiber 2 after the attachment of the first and second protective coatings, respectively, for example of the type described in US Pat. No. 4,280,827. Second and third diameter sensors 12, 13 designed to occur may be provided. The signals may be proportional to, for example, the difference between the measured diameter value and the predetermined diameter value.

The tower 1 is preferably located below the third diameter sensor 13 and is designed to detect the presence of defects such as bubbles, dents or lumps of the surface coating and to generate a signal indicating the presence of any surface defects. A defect detector 18. The detector 18 is, for example, a 360 flow detector type manufactured by BETA LASERMIKE, 8001 Technology Blvd. Dayton, Ohio, 45424, USA, 45424, Dayton, USA. Can be.

The drawing device 6 is located below the coating device 10, 11, and is preferably of a single pulley or double pulley type. In this particular case, the drawing device 6 comprises a single motor-driven pulley 14 designed to draw the fibers 2 in the vertical direction. The drawing device 6 may be provided with an angular velocity sensor designed to generate a signal indicative of the angular velocity of the pulley 14 during operation. The rotational speed of the pulley 14 and thus the drawing speed of the fiber 2 during the drawing process are process coefficients that can be changed during the drawing process to form a fiber portion having different characteristics. For example, the drawing speed of the fiber 2 may change, either by itself or with the temperature in the furnace 5, to produce a change in the internal tension of the fiber 2 and / or to produce a change in the diameter of the fiber. can do. This drawing speed is preferably greater than 5 m / s, more preferably greater than 10 m / s.

If it is desired to detect the tension of the fiber 2 during the drawing process, the tower 1 is preferably located between the furnace 5 and the drawing device 6 and generates a signal indicative of the tension of the fiber 2. It may be provided with a tension monitor device (not shown) designed to be. The monitor device may be of the type described, for example, in US Pat. No. 5,316,562.

During the drawing process, if an undesirable change occurs in the diameter of the fiber 2, the signal of the diameter sensors 8, 12, 13 automatically changes the drawing speed of the fiber 2 in order to obtain a predetermined diameter value again. It can be used to make. Indeed, if the diameter decreases below a certain threshold, the drawing speed decreases by an amount proportional to the decrease in diameter, while if the diameter increases above a certain threshold, the drawing speed increases by an amount proportional to the increase in diameter. Examples of use of diameter sensor signals and surface defect sensors are shown in US Pat. Nos. 5,551,967, 5,449,393 and 5,073,179. The number and arrangement of diameter sensors and surface defect sensors may vary from those shown.

Preferably, the tower 1 comprises a device 15 for adjusting the tension of the fiber 2, which is located between the drawing device 6 and the winding device 7 and of the tension of the fiber 2. It is designed to balance any change. The device 15 is preferably indicated in FIG. 1, under the action of its own weight and the tension of the fiber 2, with the first and second pulleys 15a, 15b mounted to revolve in a fixed position. And a third pulley 15c capable of free movement in the vertical direction. In practice, the pulley 15c is raised up if the tension of the fiber 2 undesirably increases, and lowers down if the tension of the fiber undesirably decreases, keeping the tension constant. The pulley 15c may be provided with an axial position sensor designed to indicate the vertical position of the pulley 15c and thereby generate a signal indicative of the tension of the fiber 2. A similar device for adjusting the tension of the fibers may be located upstream of the drawing device 6 as described in US Pat. No. 4,163,370.

The winding device 7 comprises a reel 16 and a member 17 for supporting and moving the reel 16. The reel 16 has an axis 16a and defines a cylindrical support surface for the fiber 2. The member 17 is designed to support and move the reel 16 near the axis 16a and along the axis 16a in a controlled manner.

The winding device 7 comprises a device 19 for feeding fibers, which is designed to feed the fibers 2 to the reels 16 in a direction generally perpendicular to the axis. In the particular embodiment shown in FIG. 1, the device 19 is positioned opposite the reel 16 and is designed to receive the fiber 2 from the tension adjusting device 15 and to feed the fiber to the reel 16. 19a). The further formed pulley 20 can guide the fibers 2 from the tension control device 15 towards the pulley 19a. Any other pulley (or other type of delivery element) can be used if necessary. The winding device 7 further comprises a linear speed sensor and, for example, an angular speed sensor (not shown) such as an encoder, which sensors move along the axis 16a and the speed of movement of the reel 16 along the axis 16a. It is designed to generate a signal indicating the rotational speed of the adjacent reel 16.

The drawing tower 1 is also electrically coupled to the sensors and detectors present along the tower 1 and to all parts of the tower 1 and that its operation can be controlled from the outside and And a control unit 21. The unit 21 is designed to control various stages of the drawing process, based on predetermined processing coefficient values and signals generated by sensors and detectors located along the tower 1. The exchange of information between the unit 21 and the various parts of the tower to which the tower 1 is coupled is shown only three of them-22, 23 and 24- for the sake of clarity. And the interface can convert the digital signals generated by the unit 21 into analog signals (e.g. electronic voltages) suitable for the operation of the individual parts and also receive from the sensors and detectors. Analog signals can be converted into digital signals to be read by the unit 21. The unit 21 also compares the count values measured by the sensors and detectors located along the tower 1 with a predetermined threshold value and indicates a j-th warning condition if one of the threshold values is exceeded. Generate a warning code (A _j ).

The three electronic interfaces 22 to 24 shown in FIG. 1 are designed to allow information exchange between the unit 21 and the drawing device 6 and the winding device 7. More specifically, the first interface 22 causes the unit 21 to send a control signal to the motor drive member of the drawing device 6 so as to control the angular velocity of the pulley 14, and also with the drawing device 6. Receive information from the combined angular velocity sensor. A second control interface, indicated by reference numeral 23, causes the unit 21 to send a control signal to the member 17 to control the rotational speed of the reel 16, and also to be coupled with the winding device 7. Receive a signal from the angular velocity sensor. The third control interface 24 allows the unit 21 to send a control signal to the member 17 to control the speed of movement of the reel 16 along the axis 16a and in combination with the winding arrangement 7. Receive a signal from a linear speed sensor.

During the winding process of the fiber 2, the translatory movement of the reel 16 allows the fiber to be spiral wound. Alternatively, spirally winding the fiber 2 to the reel 16 maintains the reel 16 fixed in the axial direction, and the pulley 19a in a direction 19b parallel to the axis of the reel 16. Can be performed by moving. This translational movement is performed by a moving member 19c (shown only approximately by a broken line) controlled by the unit 21, and the axial position of the pulley 19a is an axial position sensor (not shown). Is detected by When both the pulley 19a is fixed and the reel 16 is movable, and the pulley 19a is movable and the reel 16 is fixed, the direction in which the fibers 2 are fed to the reel 16 is In parallel, they were changed within a spatial gap having a width equal to the length of the reel 16. The method of winding the fiber 2 to the reel 16 in a controlled manner will be described below with reference to the flowchart of FIG. 6.

After the fiber is completely drawn and wound, it must be released from the reel 16 to be used. In FIG. 2, reference numeral 30 designates an apparatus for unwinding the fiber 2 from the reel 16, defining other parts of the fiber 2, and winding these parts back to the individual reel 31.

The device 30 includes a member 25 for supporting and moving the reel 16, a member (not shown) for supporting and moving the reel 31, a processing and control unit 26, and an optical sensor ( 33 and, preferably, a device 34 for adjusting the tension of the fiber, for example a device of the same type as the device 15 according to FIG. 1. If necessary, the device 30 may also include a device for automatic displacement of the reel 31, for example a device of the type described in US Pat. No. 4,138,069.

The first member 25 is designed to move the reel 16 near the axis and along the axis in a controlled manner, for example it may consist of the member 17 already used for winding. The unit 26 is designed to actuate the moving member 25 by an electronic interface 27, 28 (corresponding to interfaces 22 and 23 of FIG. 1), for example a unit 21 used for winding. It can be configured as. If the unit 26 is different from the unit 21, it is assumed that the unit has accessed all the information stored in the unit 21 before or during the drawing and winding process.

The optical sensor 33 is in parallel with a parallel light type, matrix type (including CCD photocamera) suitable for detecting the position of a body having a volume equal to the transverse volume of the fiber 2 in the sensitive area, in at least one direction. It can be composed of any other type of position detector.

The optical sensor 33 is arranged opposite to the reel 16 such that the fiber intersects the sensitive area of the optical sensor during unwinding of the fiber 2. The optical sensor 33 is electrically coupled to the processing unit 21, and during the unwinding of the fiber 2, the actual point at which the fiber 2 intersects the sensitive area and a predetermined intersection point, for example, the center point of the sensitive area and It is designed to transmit a signal S representing the distance between and to the unit 26.

The processing unit 26 is designed to use the information contained in the signal S to adjust the moving speed of the reel 16. In fact, in all cases the speed of travel changes by an amount proportional to the absolute value and the sign of the signal S, allowing the fiber 2 to pass through the sensitive area of the optical sensor 33 at a predetermined intersection, thereby minimizing the signal S. .

In each case, the distance between the actual intersection and the predetermined intersection depends on the spatial law combined with the winding pitch of the part considered. The signal S, and consequently the speed of movement of the reel 16, is therefore modulated in accordance with the laws of time correlated with the laws of space governing the winding pitch.

3 shows a possible variant of the unwinding device 30 in an approximate and partial way. The device of FIG. 3, indicated by reference numeral 30 ′, shows that the optical sensor 33 is a pivoting pulley 37 (which may be, for example, the first pulley of the tension adjusting device 34) and the angular position sensor 38. Different from the device 30 in that it has been replaced with (eg, an encoder). The pulley 37 is located in front of the reel 16 and is designed to revolve around an axis 39 which receives the fiber during unwinding and is perpendicular to the plane of the object. The angular position sensor 38 is located between the pulley 37 and the reel 16 and is measured in a direction perpendicular to the axis 16a (shown in broken lines) in which the fiber 2 reaches the pulley 37. It is designed to detect the angle α. During unwinding, the reel 16 is held fixed in the axial direction, such that angle α is correlated with the winding pitch of the portion at issue at each time point. Therefore, in a manner similar to the preceding case, the sensor 38 is designed to generate a signal S ' _e , the temporal progression of which is correlated with the spatial progression of the winding pitch.

The drawing tower 1 shown in FIG. 1 and the unwinding device 30 shown in FIG. 2 (or the device 30 'shown in FIG. 3) produce and wind fibers with different longitudinal sections, and In the course of unwinding the fiber an automated method for the subsequent definition of the parts is allowed.

During the drawing process, the fiber parts having different properties may be arbitrarily formed by changing one or more treatment coefficients (such as, for example, the temperature in the furnace 5), or an unintended change in the treatment coefficient itself or the fibers during the drawing (2). Due to the presence of a defect). For example, the fibers 2 are homogeneous and unitary throughout except at one or more ends where defects or desirable adjustments are present. A typical example of this is described in already cited US Pat. No. 4,163,370, where short fiber sections with larger diameters are formed to improve the performance of the fibers in terms of mode diffusion. In other examples of practical interest, such as those described at the beginning of this patent, the fibers may include a plurality of different adjacent portions. With respect to the description of the method according to the invention, a general example of a fiber 2 comprising _N longitudinal portions P ₁ , P ₂ ... P _N with different properties, where _N ≧ 2, is considered. .

In accordance with the present invention, during the winding process, the winding pitch is varied for each of the other fiber portions to distinguish the portion of the fiber from adjacent portions. In this way, during the subsequent unwinding process of the fiber 2, each of the other parts can be designated based on its winding pitch. Indeed, according to the invention, the individual winding pitches p ₁ , p ₂ ... p _N are associated with _N parts P ₁ , P ₂ ... P _N , which pitches are different winding pitches. It was chosen to be associated with an adjacent part. The winding pitches p ₁ , p ₂ ... p _N were chosen according to some spatial law. More specifically, the winding pitch p _i of the general portion P _i is a function of the transverse axis X measured along the axis 16a of the reel 16 and can therefore be represented by the function _pi (X). have. The minimum value of the winding pitch is defined by the diameter of the wound fiber 2. Too large a winding pitch value is avoided because it causes excessive space wastage of the reel 16. Therefore, it is possible to define the desired value range of the winding pitch. For example, for a fiber having a diameter of about 0.25 mm, the preferred winding pitch range is between 0.3 mm (selected according to working tolerance) and 3 mm.

In the simplest case, the winding pitches p ₁ , p ₂ ... p _N may have different constant values. For example, if the fiber 2 consists of four different parts P ₁ , P ₂ , P ₃ , P ₄ , the winding pitch may have the following values: p ₁ = 0.3 mm, p ₂ = 1.2 mm, p ₃ = 2.1 mm, p ₄ = 3 mm. However, the measurement of a constant winding pitch can be influenced by unpredictable factors, for example due to changes during winding phase or loosening of the fiber 2. If the fiber 2 comprises seven different parts, and thus the pitch values selected within the desired spacing are close to each other, the designation of the other parts during the fiber unwinding process can be difficult.

Preferably, the winding pitch is modulated in accordance with the spatial function of the periodic type in order to recognize the different fiber parts very accurately without depending on the number of parts present. Modulation of the winding pitch is obtained by modulating the speed of movement of the reel 16 along the axis 16a during winding, in accordance with the time function corresponding to the above-mentioned spatial function. Alternatively, if the reel 16 is fixed in the axial direction and the pulley 19a is movable in the direction 19b, the modulation is applied to the speed of movement of the pulley 19a along the axial direction 19b.

The general period time function s (t) with period T has a fundamental frequency f ₀ = 1 / T and can be represented by a Fourier series.

Where k takes all values:

Preferably, the function selected for modulating the winding pitch includes low harmonics (ie, sinusoidal components having multiples of the fundamental number) so that the fundamental frequency f ₀ can be easily extracted. More preferably, this periodic function is a sine function and therefore features a single frequency.

The modulation frequency f _mod , which coincides with the fundamental frequency of the particular periodic function selected, is therefore associated with the winding pitch.

In order to distinguish different fiber parts, it is also possible to modulate the winding pitch as a function of another type selected from among constant, sinusoidal, or periodic functions with different harmonics. For example, the first part may be wound at a constant pitch, the second part at a pitch modulated with a trigonometric type function, the third part at a pitch modulated with a sine function, and so on. Conversely, if the fiber is generally homogeneous and monolithic, with the exception of a certain number of parts, for example, if a black grating is formed along the fiber, then a constant winding pitch is assigned to the fiber, e.g. It is desirable to change the winding pitch by modulating the winding pitch with a periodic function along the portion. 4 shows, as a pure example, a winding formed according to the technique of the present invention, wherein the first layer of the winding relates to a first fiber portion P ₁ associated with a constant winding pitch, while the second layer is The pitch modulated by the periodic function relates to the associated second fiber portion P ₂ .

In order to obtain a modulation of the winding pitch in accordance with the desired periodic function, the unit 21 is a member 17 (or a member for moving the pulley if the pulley 19a is movable), which is modulated according to the desired law. You have to send a signal. This signal must have a different sign each time the wound fiber 2 completes a layer on the reel 16.

In the most common case, the moving speed v _i (t) imparted to the reel 16 (or pulley 19a) to wind the portion P _i will be the sum of the constant value and the modulation value:

v _i (t) = v ₀ (1 + F _i (t))

Where F _i (t) is a specific function selected for modulating the winding pitch of the portion P _i . The function F _i (t) may be a constant function or a more complex function as described above, preferably a periodic function s (t) as defined above.

In the simplest case of modulating a function F _i (t) of the sine function type, the moving speed v _i (t) given to the reel 16 will be the sum of the constant value and the sine value:

v _i (t) = v ₀ (1 + Asen2πf _i t)

Where f _i is the value of the modulation frequency f _mod selected for the winding of the portion P _i .

The winding pitch p is thus modulated according to a similar time law:

p _i (t) = p ₀ (1 + Bsen2πf _i t)

Where p ₀ = v ₀ T ₀ .

If the rotational speed of the reel 16 is constant, this time law can be converted into an equivalent space law, where time t is replaced by the abscissa x measured along the axis of the reel 16. For more complex periodic functions, this time and space law will include a series of harmonics.

FIG. 5 shows, as a pure example, the time course of the winding pitches p ₁ (t), p ₂ (t) with respect to the first and second portions P ₁ , P _2, respectively. The pitches p ₁ (t) and p ₂ (t) are trigonometric type functions having periods T ₁ , T ₂ and fundamental frequencies f ₁ = 1 / t 1, f ₂ = 1 / t ₂ , respectively. s ₁ (t), s ₂ (t)). Possible frequency values are, for example, f ₁ = 20 Hz and f ₂ = 8 Hz. In the example shown, the winding pitch moves between the same minimum value p _min such as 0.3 mm and the same maximum value p _max such as 3 mm.

If necessary, the amplitude of the winding pitch value associated with one part may be different from the amplitude of the winding pitch value of the other parts.

The modulation technique of winding pitch using a periodic function has a very important advantage compared to the case where the winding pitch is selected as a constant value. In fact, if the amplitude of the winding pitch value is wide enough to reduce it to a level that is negligible to neglect the effects of mechanical vibrations that normally occur during both winding and loosening, then the measurement of the winding pitch (according to the technique described below) will be very certain will be.

The method according to the invention will be described below with reference to the flowcharts of FIGS. 6 and 7. The method comprises N consecutive longitudinal sections P ₁ , P ₂ ... P _N , each of which winds a fiber 2 having at least one detectable property different from adjacent sections. It is demonstrated with reference to the process for doing it.

In the preparation step of the method (block 100), process coefficients are input to the unit 21. In particular, for each of the portions P _{i to} be formed, a set of values of the process coefficient G ₁ is input, wherein the values are selected to obtain the desired properties of the fiber 2. For each part P _{i to} be formed, an individual spatial law to be associated with the winding pitch of this part is also input. Only the preferred case where this spatial law corresponds to a periodic function that can be distinguished by the fundamental modulation frequency f _mod is considered. Unlike the value associated with the adjacent parts, the individual value f _i of the modulation frequency f _mod of the winding pitch is thus associated with each of the other parts P _i .

Based on the different parts are taken by the length and the winding speed is taken, the process and the part time interval _{(T 1, T 2 ... T} N) for the winding of the _{(P 1, P 2 ... P} N) is also determined . Normal interval (T _i) is delimited by the point (t _i) for the treatment of end portion (P _i). The unit 21 has an internal clock for measuring time from the start of the drawing process. Alternatively, instead of first defining the time intervals T ₁ , T ₂ ... T _N , the longitudinal direction of the preform 3 intended to form portions P ₁ , P ₂ ... P _N It is also possible to define parts. In this case, the general time point t _i for the end of the processing of the portion P _i is detected during the drawing process, which coincides with the end point of the portion of the preform on which the portion P _i of the optical fiber is drawn.

The coefficient setting step, in unit 21, is a frequency for modulation of the moving speed of the reel 16 for each possible process warning situation that can be detected based on signals from sensors and detectors located along the tower 1. It takes further input the individual value f _Aj of (f _mod ), where the individual value of frequency differs from that used to distinguish the parts P ₁ , P ₂ ... P _N. In practice, an individual value f _Aj of the modulation frequency f _mod is assigned to each of the warning codes A _j . The modulation time at frequency f _Aj coincides with the time of the warning situation, or if the time of the warning condition is particularly short (as in the case of surface defect detection), the modulation time coincides with the predetermined time T _Aj . do.

Once the input of the coefficients is completed, the unit 21 sends individual control signals to the various parts of the tower to which it is coupled to begin the drawing process. In particular, the unit 21 activates the various parts and defines the operating situation taken for drawing the first part P ₁ , based on the processing coefficient set G ₁ (block 110). At the same time, the unit 21 activates the clock and assigns the value 1 to the variable i, where the variable i indicates the fiber part currently being processed.

The predetermined angular rotational speed ω _{a, 1} and the moving speed v ₁ are given to the reel 16, and the moving speed v ₁ is as follows:

v ₁ (t) = v ₀ (1 + Asen2πf ₁ t)

Assuming that the rotation period T0 of the pulley 16 is constant, the winding pitch around which the first portion P1 is wound is as follows:

p ₁ (t) = p ₀ (1 + Bsen2πf ₁ t)

During the drawing process of the fiber 2, the unit 21 continues to receive signals from sensors and detectors and checks for the presence of a process warning (block 120).

If there is no process warning (option N in block 120), then the unit 21 is t <t _i ( _i for the first part P ₁ , i is 1), i.e. the processing of part P _i . And check whether the winding should continue (block 130). If t <t _i (option Y in block 130), i.e. if the processing of the portion under discussion has not yet been completed, the processing and winding of this portion continues without adjustment. On the other hand, if the processing of the part under discussion is complete (option N in block 130), then the unit 21 determines whether t <t _N , i.e. whether the drawing process of the fiber 2 should continue or has reached completion (block 140 Check). If the process completion time t _N has not yet been reached (option Y in block 140), the unit 21 increments the variable value i by one unit and increases the value f _{i + 1} to the modulation frequency f. _mod ), and select process coefficients G _{i + 1} associated with the subsequent portion P _{i + 1} (block 150). As a result, the process situation is adjusted to obtain a situation taken for the treatment of the portion P _{i + 1} . At the same time, the unit 21 sends a signal to the member 17 via the interface 23 for modulating the movement speed of the reel 16 modulated at the frequency f _{i + 1} . If the reel 16 is fixed in the axial direction and the pulley 19a is movable in the axial direction, this modulation frequency is used to modulate the moving speed of the pulley 19a. In each of these two cases, the frequency f _{i + 1} is associated with the new fiber portion P _{i + 1} .

If, during the drawing process, the unit 21 receives a signal from the sensors and detectors defining a j-th warning situation (option Y in block 120), the unit 21 generates a corresponding warning code A _j , The modulation frequency f _mod is assigned a value f _Aj associated with this warning code (block 170). The control signal modulated at the frequency f _Aj is then sent to the moving member 17 and the winding pitch is modulated according to this frequency. This situation remains until the warning signal stops or after the period T _{aj at} which the warning signal was received, after which the preexisting situation associated with the portion P _i is recovered (option N in block 120). ).

The winding process is terminated when it is detected that the time point t _N indicating the end of the process has been reached, that is to say when the last part P _N of the fiber has been processed and wound (block 160) (option N of block 140). ).

At the end of the drawing process, the fibers 2 are completely wound on the reel 16. The fiber portions P ₁ , P ₂ ... P _N form a given number of winding layers, each of which is wound with a winding pitch modulated at an individual frequency.

The unwinding process of the fiber 2 from the reel 16 is carried out with the aid of the apparatus shown in FIG. 1 or FIG. 2 and described below with reference to the flowchart in FIG.

The fiber unwinding process comprises a reel 16 and a reel 31 of a predetermined individual rotational speed selected such that the speed of unwinding the fiber 2 from the reel 16 is equal to the speed of winding the fiber 2 to the reel 31. Begin by giving to (block 200). The rotational speed ω _S of the reel 16 during unwinding may be different from the speed ω _a in the winding, generally ω _S = Kω _a where K is a constant. The speed ω _S is reached after a short starting moment.

During the unwinding process from the reel 16, the fiber 2 passes through the sensitive area of the optical sensor 33, with the result that the optical sensor generates a signal S (block 210). The same phenomenon occurs in the case of other sensors 38, and it is understood that each of the following considerations with respect to signal S are also applicable to signal S '. As explained above, the signal S is modulated in accordance with a time law similar to the space law in which the winding pitch of the fiber part discussed is modulated. In particular, the frequency f _{S at} which the signal S is modulated is associated with a frequency f _mod for modulating the winding pitch of the fiber part discussed by the formula f _S = Kf _mod .

The first loosened portion coincides with the last loosened portion, ie the P _N portion or the portion wound in the warning situation.

The unit 26 receives the signal S, extracts the frequency value f _mod , and _solves the part solved by a comparison between the extracted value and a set f _i and f _Aj of preset frequency values before the drawing process. Perform the definition of The detected modulation frequency value f _mod is assigned to variable f and stored (block 230).

In the case of the device 30 of FIG. 2, upon receiving the signal S, the unit 26 adjusts the moving speed of the reel 16 based on the absolute value and the sign of the signal S. FIG. In particular, the moving speed is adjusted to move the actual intersection of the sensitive area as close as possible to the desired intersection, so as to reduce the S value to a minimum. In this way, the moving speed of the reel 16 is modulated at the frequency f _S. The start of the unwinding process, the generation of the signal S, and the reel of the reel 16, such that the modulation of the moving speed of the reel 16 to the frequency f _S can occur substantially from the beginning of the unwinding process after a short starting moment. A very short period of time passes between the implementations of this step, including the adjustment of the speed of movement. This step involving adjusting the speed of movement of the reel 16 is not presented in the case of the release device 30 'of FIG.

After the first step process (blocks 200-220) aimed at the designation of the first unwrapped portion and the assignment of the first value to variable f, a cyclical step for determining the subsequent portions described below is followed. .

While unwinding the fiber 2, the unit 26 continuously checks whether the unwinding of the fiber 2 has been completed, for example using a signal (not shown) of the device for detecting the presence of the fiber in the reel 16. (Block 230). If the unwinding process is not complete, i.e., the reel 16 still contains fibers to be unwound (option N in block 230), the process continues and the processing unit continues with an error signal S to extract the frequency f _mod . Will be processed again (block 240). The frequency value f _mod is then compared with the value associated with the variable f by a comparison lower unit (not shown) of unit 26 (block 250). If the frequency value f _mod coincides with the value of the variable f (option Y in block 250), this means that no new part of the fiber yet exists, so the circulating step just described can be repeated without change. Can be.

On the other hand, if the frequency value f _mod is different from the value associated with the variable f (output N of block 250), this means that the unwinding of the fiber part with different properties has begun. In this case, the fiber unwinding process is blocked (block 260) and the unit 26 proceeds from the comparison of the frequency value f _mod with the stored frequency values, to the characterization of the new fiber part or the warning situation with which this frequency is associated. (Block 270). The unit 26 then sends to the actuator not shown by its own signal subunit (e.g. a display subunit) that the preceding part has been fully solved and information about the new fiber part (i.e. this part). Instructions are sent for information on the characteristics of the circuit, or if this section is wound in a warning situation, information about the warning situation that occurred during the winding, or information about any type of defect detected in the part discussed during the winding (block 280). ). At this point, the actuator can intervene to cut the fibers 2 and replace the reels 31 containing the unwrapped portions with empty reels (block 290). The unwinding process then begins again (block 300), and the steps described above (blocks 230-250 and, if necessary, 260-300) are repeated until the fiber has been fully released (option Y in block 230). If it is detected that the fiber is fully loosened, the process ends (block 310).

Included in the above.

Claims (25)

In the method of producing the fiber element (2), Drawing the fiber element from the preform (3), And forming two longitudinal portions (P _i ) having different properties of the fiber element, Winding the two longitudinal sections on a support 16; Coupling an individual winding pitch (p _i ) to each of said two longitudinal portions. In the assembly for the production of fiber elements: It comprises a production mechanism (2-5, 8-15) is designed to produce a fiber element (2) having at least two longitudinal portions (P _i), with different characteristics, and; A winding mechanism (7, 21, 22, 23) which receives the fiber element from the production tool and is designed to wind the fiber element on a support (16) to couple the individual winding pitches to the respective portions; Assembly for the production of fiber elements, characterized in that. 3. The winding mechanism 7 according to claim 2, wherein: A supply member (19a) for supplying the fiber element (2) to the support (16) in a predetermined supply direction; And Axial movement for moving one of the support 16 and the supply member 19a in a predetermined direction 16a; 19b at an axial speed correlated with a winding pitch associated with the portion relative to each of the portions. Assembly for the production of fiber elements, characterized in that it comprises a device (17; 19c). 4. The assembly according to claim 2 or 3, characterized in that the assembly comprises a mechanism for distinguishing the other longitudinal portions of the fiber element (2) wound on the support. A release device (25, 31, 34) designed to release the fiber element (2) from the support (16); And And a detection device (26, 33; 26, 38) for detecting a change in the winding pitch during the unwinding of the fiber element (2). The apparatus of claim 4, wherein the detection device is: A sensor device (33; 38) designed to generate a signal (S; S ') correlated with said winding pitch based on the sensitive area point at which said fiber element intersects; And And a processing unit (26) designed to receive the signal and obtain a value indicative of the winding pitch from the signal. 6. The assembly as claimed in claim 2, wherein the fiber element is an optical fiber and the production tool is a drawing tower. In the method of winding the fiber element 2 on the support 16, The fiber element comprises at least two longitudinal portions (P _i) having different characteristics, and; Supplying the fiber element to the support, and coupling each of the portions with an individual value of the winding coefficient _pi different from the values associated with the adjacent portion thereof. A method of winding a fiber element on a support. 8. The method of claim 7, wherein coupling the individual values of the winding coefficients _pi to each of the portions comprises coupling individual winding pitches to each of the portions. How to wind up. 9. The method of claim 8, wherein coupling the individual winding pitches p _i to each of the portions comprises coupling a separate function _si (t) for modulation of the winding pitch to each of the portions. A method of winding a fiber element to a support object, characterized in that. 10. The method of claim 9, wherein coupling the respective functions for modulation of the winding pitch to each of the portions comprises combining individual frequencies f _i , f _{A, i} for modulation of the winding pitch; And wherein said modulation frequency defines a main frequency of an individual periodic modulation function. 11. The method of any of claims 7 to 10, wherein the step of coupling individual winding pitches p _i to each of the portions is performed simultaneously with the step of feeding the fiber element to the support, Moving in a predetermined direction (16a) at a speed correlated with the winding pitch. 11. The method of any one of claims 7 to 10, wherein the step of supplying the fiber element to the support comprises guiding the fiber element in the direction of the support by a supply member 19a, wherein the portion Coupling the individual winding pitches p _i to each one comprises moving the supply member in a predetermined direction 19b at a speed correlated with the winding pitch, which is performed simultaneously with the guiding step. A method of winding a fiber element to a support object. 13. The fiber element according to any one of claims 7 to 12, wherein the fiber element 2 is an optical fiber, and the step of supplying the fiber element to the support is carried out simultaneously with the step of producing the optical fiber. And drawing the optical fiber from the preform. 14. The method of claim 13, wherein the production step is performed during the drawing step, measuring process variables and signaling an individual warning situation indicating the presence of a defective fiber portion if one of the variables exceeds a predetermined threshold. And coupling the individual value of the winding coefficient _pi to each of the portions comprises coupling the individual value of the winding coefficient _pi to the defective fiber portion. A method of winding a fiber element to a support object. In a method for distinguishing different longitudinal sections of a fiber element wound on a support, according to the method described in any one of claims 7 to 14, each of said sections is associated with an individual winding pitch: Unwinding the fiber element from the support; During said unwinding step, detecting a change in said winding pitch. The method of claim 15, wherein detecting the change in the winding pitch comprises: Repeatedly measuring coefficients correlated with the winding pitch during the solving step to obtain a continuous value of the coefficients; And Detecting a change in said count value. The method of claim 16 wherein: Comparing each of the obtained values of the coefficient with a series of stored values each associated with one of the portions; And Based on the comparison, defining longitudinal sections combined with the obtained values. 18. The method according to claim 16 or 17, wherein the step of measuring the coefficient comprises detecting a distance between an actual point where the fiber element and a predetermined area intersect and a predetermined intersection of the area. A method of distinguishing different longitudinal sections of a fiber element wound on a support. 18. The method of claim 16 or 17, wherein measuring the coefficients comprises detecting an angle between a direction of unwinding the fiber element from a support and a predetermined direction. How to distinguish different longitudinal parts. In the mechanism for winding the fiber elements (2) comprising at least two longitudinal portions (P _i) having different characteristics on a support (16): A supply member (19a) for supplying the fiber element to the support; And A moving device (17; 19c) for moving either the support or the supply member along a predetermined axis to obtain a predetermined winding pitch; A unit 21 for controlling the moving device is designed to control the moving speed so that each of the parts can engage an individual winding pitch _pi different from the winding pitch associated with the adjacent part thereof. And winding the fiber element to a support. 21. A device as claimed in claim 20, wherein at least one of the winding pitches is modulated with a periodic function. 22. A device as claimed in claim 20 or 21, wherein the fiber element (2) is an optical fiber. In a mechanism for distinguishing the different longitudinal portions of the fiber element 2 wound on the support 16, each of which is coupled with an individual winding pitch p _i : Devices (25, 31, 34) for releasing said fiber element (2) from said support (16); A sensor device (33; 38) designed to repeatedly measure a coefficient correlated with said winding pitch and generate a signal (S; S ') representing said coefficient; And And a processing unit (26) designed to receive said signal and to detect a change in said coefficient based on said signal. 24. The device according to claim 23, wherein the sensor device (33) is an optical device having a sensitive area and a reference point on the sensitive area and designed to detect a point at which the fiber element and the sensitive area intersect and a distance between the reference point. A device for distinguishing between different longitudinal portions of a fiber element wound on a support. 24. The device of claim 23, wherein the sensor device 38 is a device designed to detect an angle between a direction of unwinding a fiber element from the support and a predetermined direction. Mechanism to distinguish.