EP1031524A2

EP1031524A2 - Yarn winding apparatus

Info

Publication number: EP1031524A2
Application number: EP00103006A
Authority: EP
Inventors: Satoshi Nomura; Masakatsu Hasegawa; Katsufumi Muta
Original assignee: Murata Machinery Ltd
Current assignee: Murata Machinery Ltd
Priority date: 1999-02-26
Filing date: 2000-02-14
Publication date: 2000-08-30
Also published as: EP1031524A3

Abstract

The shock imparted by the contact roller against the package when a yarn winding apparatus switches from gap winding to normal winding is lessened. An elastic holding means 21, such as a plate spring or the like, is positioned between frame 6 and slide box 7. The slide box 7 can be raised and lowered relative to the frame 6, and holds a contact roller 5. The elastic holding means 21 exerts elastic counter-force in the opposite direction to that in which the contact roller 5 is drawn to the package 3. This softens the sudden spike in contact pressure normally seen when the contact roller 5 makes contact with the package 3. Additionally, the distance of separation between the contact roller 5 and the bobbin 2 can be reliably maintained at the pre-set level during gap winding. This makes it easier to estimate the exact contact time at which the contact roller 5 will meet the package 3, thereby enabling the switch from programmed control of the bobbin rotation speed to feedback control of the bobbin rotation speed to be timed precisely to the moment of contact between the contact roller 5 and the bobbin 2.

Description

Technical Field

The present invention relates to a yarn winding apparatus that forms a package by winding a man-made filament yarn around a bobbin, and more particularly to an apparatus that prevents damage to the yarn by softening the severe spike in contact pressure that occurs during the initial stages of winding when a contact roller that is initially held away from the bobbin is brought into contact with the package.

Background of the Invention

A yarn winding apparatus forms a package by winding a man-made filament yarn around a bobbin held on a freely rotating bobbin holder. The winding speed of the yarn is held constant by controlling the rotary speed of the bobbin holder. Generally, this control is facilitated by provision of a contact roller that rotates in contact with the surface of the package in order to stabilize the package. The rotary speed of the contact roller is used for feedback control to control the rotary speed of the bobbin holder.
Since the bobbin and the contact roller are rotated at extremely high speeds, contact between the contact roller and the bobbin at the start of winding creates a variety of problems. The heavy pressure of the contact roller against the thin layers of yarn during the early stages of winding may damage the yarn. Further, the early contact generates loud noise, and may even destroy the inner paper core of the package that comprises the bobbin. Using a more rigid paper core could possibly prevent the paper core from being damaged, but this greatly increases the cost of the bobbin, and still does nothing to solve the other problems.
To avoid these problems, prior art yarn winding apparatus often use a process called "gap winding", in which the contact roller is separated from the bobbin at the start of winding. There are generally two types of gap winding methods. In one method, the contact roller is held a predetermined distance away from the bobbin at the start of winding, and passively comes into contact with the bobbin as the wound package grows in diameter. In the other method, the contact roller is held away from the bobbin for a predetermined amount of time from the start of winding, after which time it is actively brought into contact with the package.
Still, these prior art gap winding methods do not resolve all the problems that arise when the roller and the bobbin first make contact. Specifically, the rotary speed of the bobbin holder cannot be accurately controlled during this initial winding period because the contact roller, the rotary speed of which is used to control the speed of the bobbin holder, is not in contact with the bobbin. More to the point, the peripheral speed of the yarn package (i.e., the winding speed) oust be measured in order to control the bobbin holder rotary speed so that it doesn't exceed or fall below the winding speed, and this winding speed cannot be measured while the contact roller is not in contact with the package. Thus, in the prior art gap winding procedures, control of the bobbin holder rotary speed must be based on a pre-programmed function that estimates the bobbin holder rotary speed needed to match the winding speed during the initial winding period, and only after the yarn package has reached a predetermined size or a predetermined amount of time has passed can the machine switch to control based on actual rotary speed measurements of the contact roller.
In order to obtain the highest quality yarn and to prevent the bobbin holder from accelerating too quickly, the contact roller must be introduced into contact with the package, but since in the first prior art gap winding method contact begins after the package reaches a certain size, it is difficult to predict the exact time at which contact will begin, and there is a great danger that the apparatus will switch to feedack control at the wrong time.
In the second prior art gap winding method, since the contact roller is actively introduced into contact with the package after a fixed period of time, it is easy to predict when contact begins, enabling the machine to switch to feedback control at the right time, but because the contact is actively introduced, the contact force of the roller against the package immediately jumps from zero to the normal winding force, and this may adversely affect the yarn. Furthermore, it is difficult to match the speed of the contact roller to the package speed when the contact roller is introduced into contact with the package. Discrepancies in speed any cause the yarn to break or otherwise reduce yarn quality. In contrast to the rotary speed of the contact roller, which is ideally a constant speed, the rotary speed of the bobbin holder must be slowly reduced as the package grows larger in order to maintain a constant winding speed (i.e. to keep the periphery of the package rotating at a constant speed). In order to precisely control this gradual reduction in speed, feedback control is performed based on the speed of the contact roller. But during the initial stages of winding, since the speed of the package cannot be measured, the bobbin must be rotated according to a predetermined function. As the package grows during the initial stages of winding, when the package is not in contact with the contact roller, it can be extremely difficult to accurately pre-set the speed of the bobbin holder to match the actual peripheral speed of the package. Consequently, at the moment the roller and package make contact, the peripheral speed of the package often varies from the yarn production speed.

Summary of the Invention

It is an object of the present invention to provide a yarn winding apparatus that makes it easier to determine the proper time to switch to feedback control of the bobbin holder, and that lessens the sudden spike in contact pressure when the contact roller meets the package at the moment gap winding ends.
In order to accomplish this object, according to a first aspect of the present invention, a yarn winding apparatus comprises a freely rotatable bobbin holder upon which a bobbin is set, a package of yarn formed around the bobbin, a contact roller that contacts said package, and a holding mechanism that holds said contact roller a predetermined distance away from said bobbin, wherein said holding mechanism draws the contact roller towards said package, and wherein said holding mechanism is provided with a means for operating an elastic counter-force in a direction opposed to that in which said contact roller is drawn.
In the yarn winding apparatus of the present invention, the elastic counter-force means is an elastic, compressable space holding member.
Additionally, the elastic counter-force means any be further provided with a control means for controlling the force with which the contact roller is held in order to adjust the pressure with which the contact roller contacts the package, wherein control means brings the contact roller into contact with the package by controlling the force with which the contact roller is held.
It is a second object of the present invention to provide a yarn winding apparatus capable of matching the peripheral speeds of the contact roller and the package as much as possible when gap winding is ended and the contact roller is brought into contact with the package to start normal winding. Thus, according to one aspect of the present invention, a yarn winding apparatus that comprises a freely rotatable bobbin holder onto which a bobbin is placed, a yarn package wound around said bobbin, a contact roller that contacts said package, a rotary driving means that drives said bobbin holder, a rotary driving means that drives said contact roller, and a controller that controls the rotary driving of said bobbin holder and said contact roller, the apparatus comprised such that the distance of separation between the bobbin holder and the contact roller are adjustable, characterized in that the controller controls the rotary speed of the bobbin holder based on a predetermined function at the start of winding, when the contact roller and the bobbin are held in a non-contact state; switches rotary driving control of the bobbin holder to control based on the detected rotary speed of the contact roller after the contact roller has been brought into contact with the package being formed around the bobbin; adjusts the function based on the rotary speed of the bobbin holder after control has been switched over; and sets the rotary driving control of the bobbin holder to be used during subsequent windings.
Further, in another aspect of the yarn winding apparatus of the present invention, the adjustment of the function is based on the disparity between the rotary speed command values given to the bobbin holder rotary driving means after control has been switched, and the estimated rotary speed command values based on the function.
Still further, the yarn winding apparatus of the present invention may additionally comprise a holding force control means for controlling the force with which the contact roller is held, and wherein the switching of rotary driving control of the bobbin holder is performed based on signals to change the holding force output by the holding force control means.

Brief Description of the Drawing

Figure 1 shows an outline view of an embodiment of the yarn winding apparatus of the present invention during normal winding.
Figure 2 shows an outline view of an embodiment of the yarn winding apparatus of the present invention at the start of gap winding.
Figure 3 shows an embodiment of the bobbin holder and the contact roller rotary drive mechanism in the yarn winding apparatus of the present invention, as well as an outline view of the structure of an embodiment of a regulator provided inside a controller.
Figure 4A and 4B show outline views of the main parts of the contact roller holding force control means of the yarn winding apparatus of the present invention. Figure 4A shows staged control, and Figure 4B shows stageless control.
Figure 5 shows an outline view of an embodiment of the elastic holding means of the yarn winding apparatus of the present invention.
Figure 6 shows an alternate embodiment of the elastic holding means of the yarn winding apparatus of the present invention.
Figure 7 shows an outline view of still another embodiment of the elastic holding means of the yarn winding apparatus of the present invention.
Figure 8 shows an outline view of yet another embodiment of the elastic holding means of the yarn winding apparatus of the present invention.
Figure 9 is a flow chart showing the winding process employed in the yarn winding apparatus of the present invention.
Figure 10 shows an outline view of the main parts of a yarn winding apparatus of the present invention. Figure 10A shows the apparatus just before gap winding is terminated, and Figure 10B shows the contact roller in contact with the package.
Figure 11 is a graph showing the speed at which the bobbin holder motor is instructed to rotate over time in the yarn winding apparatus of the present invention.
Figure 12 is a graph showing the change in contact pressure when the contact roller is brought into contact with the package at the end of gap winding.

Detailed Description of the Preferred Embodiments

Embodiments of the yarn winding apparatus of the present invention will now be explained with reference to the accompanying drawings. Figure 1 and Figure 2 show the outlined structure of a take up winder 1 that winds continuously supplied synthetic melt-spun yarn (man-made filament yarn) around a bobbin 2, forming a package 3. Figure 1 shows the apparatus during normal operation, and Figure 2 shows the apparatus when it first begins winding.
In both drawings, the yarn winding apparatus 1 is provided with two freely rotatable bobbin holders 4a, 4b, each bobbin holder supporting a plurality of individual bobbins 2, and with a contact roller 5 capable of contacting the yarn packages 3 formed by the yarns wound around the bobbins 2 on the top bobbin holder 4a. One of the bobbin holders 4a is in the winding position, and the other bobbin holder 4b is in the stand-by position. The apparatus is capable of automatically switching the positions of the bobbin holders, simultaneously switching the bobbin holder in the winding position (in this case, 4a) with the bobbin holder in the stand-by position (in this case, 4b). Additionally, a traverse mechanism and a yarn mounting mechanism are also provided, but not shown in the drawings.
The bobbin holders 4a, 4b are movably attached to the frame 6 of the apparatus 1. The contact roller 5 is attached to a slide box 7, which is attached to the frame 6 so that it can be elevated or lowered therefrom. The distance between the contact roller 5 and the bobbin holder in the winding position (in this case, 4a) can be adjusted by elevating or lowering the slide box 7. Movement of the slide box 7 is guided by a slide shaft 8 arranged on the frame 6. A holding force control means 9 controls the amount of contact force between the contact roller 5 and the package 3 by controlling the amount of force with which the contact roller 5 is held. This holding force control means 9 may be comprised, as shown in the present embodiment, as a holding force controller (an air cylinder, for example) engaged with a piston shaft 10 that extends upwards from frame 6 to the inside of a cylinder chamber 11 arranged inside the slide box 7, a compressed air supply source 12 that supplies compressed air towards the cylinder chanter 11, and a pressure adjusting device 13 that controls the supply of compressed air. The holding force control means 9 could then adjust the amount of force with which the contact roller 5 is held by controlling the air pressure of the compressed air supplied to the cylinder chanter 11. For example, reducing air pressure would make the slide box 7 heavier, increasing the downward force exerted by the contact roller 5 towards the surface of the bobbin 2. In other words, the force with which the contact roller 5 is held would decrease, thereby increasing the contact pressure. Alternatively, increasing the air pressure would increase the force buffeting the slide box 7, increasing the force with which the contact roller 5 is held, thereby reducing the contact pressure.
As shown in Figure 3, the bobbin holder 4a is rotationally driven by a motor 14a, and the contact roller 5 is rotationally driven by a motor 14c. The rotary speeds of the two motors 14a, 14c are controlled by a pair of sensors 15a, 15c, and a controller 16. The sensor 15a measures the rotary speed of the bobbin holder 4a, and the sensor 15c measures the rotary speed of the contact roller 5. Although not shown in the drawings, the second bobbin holder 4b in the standby position is comprised similarly to the bobbin holder 4a in the winding position, and is driven by its own motor, and provided with its own sensor.
The control unit 16 any employ inverters 17a, 17c and a regulator 18, and be provided with a setting unit to set the various parameters needed to control the winding process. The regulator 18 is provided with a number of units that provide various functions needed to control the winding process. These units include a first timer unit, a second timer unit, a gap winding control unit, a feedback control unit, a control switching unit, a formula storage unit, and an adjustment processing unit. The functions of these units will be explained below.
The pressure adjusting device 13, which serves as a holding force control means for adjusting the contact pressure exerted by the contact roller 5 against the package 3, may be comprised as a multi-stage valve as shown in Figure 4A. In such a multi-stage valve, one or more of a plurality of pressure reducing valves and opening valves can be selectively opened or closed to adjust the pressure of the compressed air supplied to the cylinder chamber 11. Adjusting the supply pressure changes the force with which the contact roller 5 is held.
Figure 4A shows an arrangement of three pressure reduction valves 19a, 19b, 19c, and three opening valves 20a, 20b, 20c, operable to provide three levels (light, moderate, and heavy) of contact pressure (i.e. force with which the contact roller 5 is held). Figure 4B shows an alternative arrangement in which the pressure adjusting device 13 employs an electro-pneumatic regulator. In such case, pressure can be freely adjusted, and is not restricted to pressure" levels."
The winding process performed by the yarn winding apparatus 1 is controlled such that, during normal winding, as shown in Figure 1, when the yarn is wound around the surface of the bobbin 2 on the bobbin holder 4a to form the package 3, the contact roller 5 is brought into contact with the surface of the package 3 and exerts a predetermined force against the package 3. The speed of the contact roller 5 is controlled such that it matches the yarn production speed, and such that those speeds are held constant. As the yarn is wound around the package 3, the package 3 grows larger in diameter, requiring the rotary speed of the bobbin holder 4a to be gradually decreased in order to maintain a constant winding speed, i.e. to keep the peripheral speed of the package 3, with which the contact roller 5 is in contact, constant. The speed reduction is controlled by PI-type or similar feedback control based on the rotary speeds of the bobbin holder 4a and the contact roller 5 detected by the sensors 15a, 15c, respectively.
Although the entire winding process lasts until an empty bobbin is turned into a full package, during the gap winding process at the start of winding, as described hereinbefore and shown in Figure 2, the contact roller 5 is held at a predetermined distance away from the bobbin 2. The gap winding process continues until the the package of yarn around the bobbin reaches a predetermined thickness. As in normal winding, the rotary speed of bobbin holder 4a must be gradually reduced in order to maintain a constant winding speed, but since feedback control using the rotary speed of the contact roller 5 cannot be performed during the gap winding process, control is performed instead such that the rotary speed of the contact roller 5 is reduced based on a predetermined function estimating the reduction in speed of the bobbin holder 4a. In other words, the time it takes for the package 3 to reach the predetermined thickness is estimated, and the force with which the contact roller 5 is held is reduced at the point when the estimated appropriate amount of time from the start of winding has elapsed. At the same time as when the contact roller 5 is brought into contact with the surface of the package 3 or depending upon conditions, some time after that control of the rotary speed of the bobbin holder 4a is switched from control based on the predetermined function to PI feedback control based on the rotary speed of the contact roller 5 for the duration of winding. In reality, however, the rotary speed of the package 3 based on the programmed function and the predetermined yarn production speed are sometimes different at the moment when the contract roller 5 is brought into contact with the package 3, and so it is desirable to provide a system for appropriately supplementing the programmed function.
In order to maintain separation between the contact roller 5 and the bobbin 2 during gap winding, and in order to facilitate adjustment of the distance between the contact roller 5 and bobbin 2, the apparatus 1 of the present embodiment employs a elastic holding means 21 that exerts elastic counter-force upwards against the slide box 7, in other words, in the opposite direction from that in which the contact roller 5 approaches the bobbin 2, when the force supporting the contact roller 5 is reduced, lowering the slide box 7 and bringing the contact roller 5 into contact with the surface of the bobbin 2. Examples of the elastic holding means 21 include the plate spring of Figure 5, the coil spring shown in Figure 6, and the rubber body of Figure 7. This elastic holding means 21 is arranged between the slide box 7 and the frame 6 such that it presses upward from the frame 6 to the slide box 7. These elastic holding means 21 serve as space holding members that can be compressed in the direction in which the contact roller 5 approaches the bobbin 2. Alternative embodiments of the elastic holding means 21 include a spring arranged on top of the slide box 7, that applies force in an upward direction, lifting the slide box 7 upwards. The elastic holding means 21 any alternatively be comprised as a pneumatic or hydraulic device using hydraulic or pneumatic force.
The elastic holding means 21 should preferably be comprised such that elastic countervailing force is exerted upwards against the slide box 7 only when, during gap winding, the contact roller 5 and the bobbin 2 are separated by a predetermined distance (1mm, for example). Additionally, an elastic force-applying space holding member may also be provided in order to stabilize the position at which the contact roller 5 is held providing a predetermined amount of force against the space holding member. The elastic holding means 21 is comprised such that as the distance between the contact roller 5 and the bobbin 2 becomes smaller, the amount by which the elastic holding means 21 is compressed increases, thereby increasing the elastic countervailing force. Thus, by arranging the elastic holding means 21, the load exerted by the holding force control means to hold the contact roller 5 (a predetermined air pressure) is reduced, and when the contact roller 5 is brought into contact with the package 3, elastic countervailing force is applied, supplementing the force with which the contact roller 5 is held. This enables the severe spike in contact pressure between the contact roller 5 and the package 3 to be restrained when the contact roller 5 is brought into contact with the package 3, as shown in the graph in Figure 12. By adjusting the elastic countervailing force of the elastic holding means 21, the contact pressure at the time of contact can be set to 0 or to any fraction the normal winding pressure, thus allowing the contact pressure at the contact time to be optimally set for various different winding conditions with relative ease.
When the slide box 7 and the elastic holding means 21 are brought into contact during gap winding, as shown in Figure 2, since the position at which the slide box 7 stops is stabilized, making it easy to maintain a fixed degree of separation between the contact roller 5 and the bobbin 2. Further, the normal 1mm gap winding setting can be adjusted by varying the amount of force with which the contact roller 5 is held. Still further, if the elastic holding means 21 is comprised as a space holding meter, as shown in Figure 5 ∼ Figure 7, its structure can be greatly simplified. Further still, after the contact roller 5 and the package 3 have been brought into contact, the contact pressure can be gradually raised to the normal winding contact pressure as the package grows in size (see Figure 12). In fact, the present invention allows the period between the moment of contact between the contact roller 5 and the package 3 and the point at which the contact pressure reaches the normal winding pressure to be adjusted.
An actual example of the winding process performed by the yarn winding apparatus 1 of the present invention will now be explained. An example of the winding process is shown in the flow chart of Figure 9.
At the start of winding, gap winding is performed, and the contact roller 5 and the bobbin 2 are separated by a fixed gap winding distance, as shown in Figure 2. In the case where the holding force control means 9 is comprised as the pressure adjusting device 13 as shown in Figure 4A, the opening valve 20c, which sets the holding force to maximum, is turned ON. The pre-set pressure of the compressed air used by the holding force control means 9 can then be reduced during gap winding, since the slide box 7, which holds the contact roller 5, receives elastic countervailing force directed upwards from the elastic holding means 21. This then makes it easy to hold the contact roller 5 in the gap winding position. Additionally, the presence of the elastic holding means 21, which is in contact with the slide box 7, enables the distance of separation between the contact roller 5 and the bobbin 2 to be stabilized. Moreover, it should be noted that the elastic holding means 21 be comprised as a spring.
Gap winding control is performed by a first timer unit, a gap winding controller, and function storage unit (see Figure 3), which are provided in the regulator 18 inside the controller 16. The first timer counts the time from the start of winding until the end of the gap winding process (i.e. it counts the gap winding period). When the gap winding period ends, the timer outputs a signal to the pressure adjusting device 13 of the holding force control means 9 indicating that the force with which the control roller 5 is held should be changed. The gap winding time is pre-calculated and pre-stored as a function of the package thickness. The gap winding controller controls the rotary speed of the motor 14a that drives the bobbin holder 4a. During gap winding, the controller decreases the rotary speed of the motor 14a based on a function stored in the function storage unit.
By performing gap winding for a predetermined amount f time, the package 3 formed on the bobbin 2 grows larger, reaching a predetermined thickness, as shown in Figure 10A. After the predetermined amount of gap winding time has elapsed, the first timer outputs a holding force change signal to the pressure adjusting device 13, reducing the holding force of holding force control means 9. As a result, the contact roller 5 is brought into contact with the package 3, as shown in Figure 10B. The reduction in holding force may be accomplished, for example, by opening the second valve 20b of the pressure adjusting means 13 shown in Figure 4. At this point, the slide box 7 receives an elastic countervailing force from the elastic holding means 21, which restrains the contact pressure between the contact roller 5 and the package 3.
Consequently, there is no sever spike in contact pressure when the roller 5 and the package 3 are introduced, and problems such as yarn breakage and reduction in yarn quality can be greatly minimized.
The force changing signal output by the first timer is also output to the control changing unit, which changes control of the motor 14a for the bobbin holder 4a to feedback control via the feedback control unit. Feedback control unit controls the rotary speed of the motor 14a based on the rotary speed of the control roller 5 detected by the sensor 15c. The actual form of this control may be the PI control or the like. The control method may be switched immediately upon contact between the contact roller 5 and the package 3, or may begin after a predetermined amount of time has elapsed therefrom. Accordingly, since the contact roller 5 is actively brought into contact with the package 3, the determination of exactly when to make the switch from rotating the package at an estimated, pre-set rotary speed to rotating it under feedback control based on the detected rotary speed of the contact roller 5 can be made even more precisely.
During gap winding, in order to maintain the yarn winding speed at the fixed yarn production rate, the motor 14a that rotates the bobbin holder 4a is controlled by the gap winding control unit based on a function stored in the function storage unit such that the speed of the bobbin holder is gradually reduced. The function used to control this speed reduction is shown below as function X.
The symbols used in this function are defined as follows:
ω is the rotary speed (rpm) of the bobbin holder after t minutes have elapsed from the start of winding.
ω_o is the initial rotary speed (rpm) of the bobbin holder at the start of winding.
Q is the yarn extrusion amount (g/min)
t is the amount of time (minutes) elapsed since the start of winding.
W is the traverse width (mm)
ρ is the winding density (g/cm³)
R_o is the bobbin radius (mm)
π is pi
The initial value of the winding density ρ may be set to best suit the type of yarn used (polyester, nylon, etc.), or it may be set according to the traverse angle.
When the contact roller 5 is brought into contact with the package 3 from its gap winding position, there are times when the actual thickness of the package 3 differs from the pre-set package thickness, resulting in a disparity between the peripheral speed of the package 3 and the rotary speed of the contact roller 5. One reason for this is that during yarn winding, particularly during gap winding, it is extremely difficult to maintain a precisely constant yarn tension. When yarn tension varies, the winding density may vary from its pre-set value. Additionally, when other factors such as the yarn type and the traverse angle change, the package thickness may change as well. The present invention therefore employs the following method in order to correct such disparities between the peripheral speed of the package being wound according to the programmed function and the actual yarn production speed.
During the gap winding portion of yarn winding, the rotary speed of the bobbin holder 4a is controlled based on the stored function X. Referring to the graph of Figure 11, the rotary speed command values given to the motor 14a for the bobbin holder 4a during this period (from time 0 to time T1, as indicated in Figure 11) are indicated in line n1. At time T1, when the contact roller 5 is brought into contact with the package 3, or alternatively at a predetermined amount of time shortly thereafter, rotary speed control of the bobbin holder 4a is switched to feedback control. If at this point there is a difference between the peripheral rotation speeds of the contact roller 5 and the package 3, the changes in rotary speed command values over time after switching over to feedback control may appear as indicated in curve n2.
In the present embodiment of this invention, a compensating means is provided in order to eliminate this speed difference. After control over the bobbin holder 4a has been switched to feedback control, the compensation means compares the rotary speed command values MV_P1 that are actually output to the motor 14a for the bobbin holder 4a with the estimated rotary speed command values MV_cal calculated by the pre-programmed function X. The compensation means then changes the winding density ρ in the function X based on the amount of disparity between the two values.
This compensation means is arranged inside the regulator 18. The control switching unit, which receives the holding force change signals from the first timer, switches control over motor 14a to feedback control, and outputs control switching signals to the second timer. After receiving the control switching signals, the second timer counts a predetermined amount of time (a few seconds, for example). After the predetermined amount of time has elapsed, the compensating unit calculates the proper amount by which the winding density ρ in Function X should be compensated, and then overwrites the function stored in the function storage unit with a new function that uses the calculated compensation amount. In other words, when subsequent winding is carried out, the winding density ρ in Function X will be replaced with a new density ρ_n that has been derived from the current winding density setting ρ_n-1 using the following compensation formula A. ρn = MVp1 2 · (MV0 2 - MVcal 2)MVcal 2 · (MV0 2- MVp1 2) · ρn-1
The symbols used in this function are defined as follows:
ρ_n is the winding density substituted for ρ in function X, and used for the estimated rotary control during gap winding.
ρ_n-1 is the current winding density used in function X during the present gap winding process.
MV_o is the rotary speed command value output to the motor for the bobbin holder 4a at the start of winding.
MV_P1 is the actual rotary speed command value output to the motor for the bobbin holder 4a after a predetermined amount of time has passed since control over the rotation of the bobbin holder was switched to feedback control.
MV_cal is the rotary speed command value output to the motor for the bobbin holder 4a, corresponding to the estimated rotary speed ω of the bobbin holder as calculated by Function X. Output of these values begins after a predetermined amount of time has elapsed since control over the rotary speed of the bobbin holder was switched to feedback control.
Although the present embodiment contemplates that the winding density ρ will be adjusted each time winding is carried out, it should be noted that such adjustments may be performed only once per specified number of windings.
When the adjustment is made in the winding density, the estimated rotary speed command values output to the motor 14a for the bobbin holder 4a are shifted over subsequently performed windings from the n1 curve in Figure 11 represented by the dotted line towards the n0 winding curve that corresponds to the actual winding values. By repeating this adjustment process with function A each subsequent winding, or periodically every few windings, the original disparity in peripheral speed at the moment of contact between the contact roller 5 and the package 3 on the bobbin holder 4a can be reduced each time the adjustment is performed. In other words, to the extent that the winding conditions and the environment does not change, the initial disparity between the peripheral rotary speeds of the contact roller 5 and the package 3 can be substantially eliminated. In other words, the present invention enables the peripheral speed of the contact roller 5 to substantially match that of the package 3 at them moment the contact roller 5 is introduced to the package 3, thereby preventing damage to the yarn and yarn breakage.
It is preferable that a ceiling be set on the absolute value of the compensation amount calculated using function A. It is preferable to set the ceiling because if the calculated value is very high, it is quite likely that there is an abnormality in the yarn winding apparatus. Extremely large compensation values may influence subsequent calculations and result in a succession of erroneous, abnormally high calculations. Further, when the compensation amount is abnormally high, it may result in repetitive yarn breakage or other problems. Thus, setting an upper limit on the compensation amount helps prevent abnormal yarn density compensation values in successive yarn windings. Additionally, restricting the size of the compensation amount allows faster elimination of the disparity between the estimated rotary speed of the bobbin holder and the actual yarn production speed. Moreover, the present invention may be comprised such that calculated compensation amounts that exceed a predetermined level are ignored, or so that such excessive values trigger an alarm, since this would tend to indicate a malfunction or abnormality with the apparatus.
In the present embodiment, control over the motor 14a is switched from control based on the function of the estimated rotary speed to feedback control when the contact roller 5 is brought into contact with the package 3 at the end of gap winding. This switch-over may be set to occur upon the output of signals instructing the force with which the contact roller 5 is held to be changed. By decreasing the force with which the contact roller 5 is held, the contact roller 5 begins to be lowered towards the package 3 until they make contact. Consequently, by setting the switch to feedback control to occur an appropriate predetermined amount of time after output of the holding force changing commands, the moment at which the contact roller 5 makes contact with the package 3 and the moment at which the control is switched over can be easily synchronized. Further, the presence of the elastic holding means 21 between the frame 6 and the slide box 7, which holds the contact roller 5, the position at which the slide box 7 comes to rest during gap winding can be stabilized, and the amount of time it takes for the contact roller 5 to be lowered into contact with the package 3 can be made constant. Thus, synchronization of contact between the contact roller 5 and the package 3, and the switch to feedback control of the motor 14a can be made more precise.
It should be noted that this kind of timer-based control is preferable to other methods, such as use of a sensor. Due to problems with the sensor's ability to accurate detect the moment of contact between the contact roller 5 and the package 3, switchover to feedback control will almost always occur after the nunent of contact.
In the current embodiment of the present invention, a setting unit is arranged in the controller 16 for controlling the operation of the winding device. Predetermined parameters and a predetermined winding program may be input into the setting unit. Factors that can be input into the setting unit include function X, the yarn extrusion amount Q, traverse width W, bobbin radius R, the initial winding density value ρ_o as well as yarn winding speed V_o, contact roller contact pressure, the contact roller gap width at the start of winding, and the timing period between the start of gap winding and the switch to feedback control. It should also be apparent that the rotary speed of the bobbin holder ω_o, the winding speed setting V_o, and the radius R of the bobbin are all calculated automatically.
Since the winding density compensation amount is calculated each time yarn winding is performed, it may be displayed on a screen, by computer print out, or by similar method. Providing a display means for the winding density compensation amount then allows this value to be operator to continuously monitored by a machine operator.
Additionally, it should be noted that even if yarn winding is suspended, when the winding process is then resumed, utilization of the compensation amount allows the winding process to be improved.
Since the yarn winding apparatus of the present invention is provided with an elastic holding means that exerts elastic countervailing force when the contact roller is drawn towards the package, the severe spike in contact pressure exerted by the contact roller against the package when contact is initiated after gap winding is greatly reduced. Consequently, adverse effects on the yarns of the bobbin when the contact roller is brought into contact with the package can be substantially eliminated, damage to the yarn and yarn breakage can be greatly reduced.
Additionally, since the position at which the contact roller stops when it is held by the elastic holding means during gap winding is stabilized, the distance (the gap width) between the contact roller and the bobbin is nearly the exact separation setting. This makes it much easier to estimate the amount of time it takes front the point when the contact roller begins to be lowered toward the package until the contact roller and the package actually make contact. Consequently, the change from gap winding to normal winding position and the switch of rotary control of the bobbin holder to feedback control can be more accurately synchronized.
Further, in another aspect of the yarn winding apparatus of the present invention, since the function used to control the winding speed of the bobbin holder during gap winding is adjusted each time the winding process is performed, the disparity in peripheral rotary speeds between the contact roller and the package when the contact roller and the package are first moved from the gap winding position to the normal winding position can be reduced with each successive winding, eventually substantially eliminating this difference. Consequently, it is eventually possible to nearly match the peripheral rotary speeds of the contact roller and the package when they are shifted from gap winding to normal winding positions, and damage to the yarn as well as yarn breakage can be greatly reduced. Further, sudden changes in the rotary speed of the bobbin holder that occur when switching to feedback control when the contact roller is brought into contact with the package can be prevented by compensation of the stored winding function.
Further, in a fifth aspect of the yarn winding apparatus of the present invention, since the rotary speed command value given to the bobbin holder rotary driving means is used to adjust the function used in the estimates to control the rotary speed of the bobbin holder, control that is significantly less complicated and more reliable than compensation based on detection of the actual rotary speed of the bobbin holder can be achieved.
Still further, in a sixth aspect of the yarn winding apparatus of the present invention, since the moment that signals directing a change in the holding force of the holding force control means are output is used to determine the point at which control of the bobbin holder is switched to feedback control, the moment feedback control is switched over can be accurately synchronized to the moment the contact roller makes contact with the package.

Claims

a yarn winding apparatus provided with a freely rotatable bobbin holder onto which a bobbin is placed, a package of yarn wound around said bobbin, a contact roller which contacts said package, and a holding mechanism that holds the contact roller a predetermined distance away from the bobbin, characterized in that;

a countervailing force applying means that exerts elastic force in the direction opposite to that in which the contact roller is drawn to the bobbin when the contact roller is drawn towards and brought into contact with the package is provided.
A yarn winding apparatus as in claim 1 wherein the elastic counter-force means is a space holding member capable of elastically contracting.
A yarn winding apparatus as in claim 1 or claim 2 wherein the elastic counter-force means is provided with a control means that controls the force with which the contact roller is held in order to adjust the contact pressure applied by the contact roller against the package, and wherein the contact roller and the package are brought into contact through control by the holding force control means of the force with which the contact roller is held.
A yarn winding apparatus comprising a freely rotatable bobbin holder onto which a bobbin is placed, a package of yarn wound around said bobbin, a contact roller that contacts said package, a rotary driving means that drives said bobbin holder, a rotary driving means that drives said contact roller, and a controller that controls the rotary driving of said bobbin holder and said contact roller, the apparatus comprised such that the distance of separation between the bobbin holder and the contact roller are adjustable, characterized in that the controller controls the rotary speed of the bobbin holder based on a predetermined function at the start of winding, when the contact roller and the bobbin are held in a non-contact state; switches rotary driving control of the bobbin holder to control based on the detected rotary speed of the contact roller after the contact roller has been brought into contact with the package; adjusts the function based on rotary speed of the bobbin holder after control has been switched over; and sets the rotary driving control of the bobbin holder to be used during subsequent windings.
A yarn winding apparatus as in claim 4 wherein the adjustment of the function is based on the disparity between the rotary speed command values given to the bobbin holder rotary driving means after control has been switched, and the estimated rotary speed command values based on the function.
A yarn winding apparatus as in claim 4 or claim 5 further comprising a holding force control means for controlling the force with which the contact roller is held, and wherein the switching of rotary driving control of the bobbin holder is performed based on signals to change the holding force output by the holding force control means.