CA1052460A - Warp tension controller - Google Patents
Warp tension controllerInfo
- Publication number
- CA1052460A CA1052460A CA241,776A CA241776A CA1052460A CA 1052460 A CA1052460 A CA 1052460A CA 241776 A CA241776 A CA 241776A CA 1052460 A CA1052460 A CA 1052460A
- Authority
- CA
- Canada
- Prior art keywords
- output
- warp tension
- operational amplifier
- loom
- voltage
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D15/00—Control of mechanical force or stress; Control of mechanical pressure
- G05D15/01—Control of mechanical force or stress; Control of mechanical pressure characterised by the use of electric means
-
- D—TEXTILES; PAPER
- D03—WEAVING
- D03D—WOVEN FABRICS; METHODS OF WEAVING; LOOMS
- D03D49/00—Details or constructional features not specially adapted for looms of a particular type
- D03D49/04—Control of the tension in warp or cloth
- D03D49/06—Warp let-off mechanisms
Landscapes
- Engineering & Computer Science (AREA)
- Textile Engineering (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Automation & Control Theory (AREA)
- Looms (AREA)
Abstract
ABSTRACT
Warp tension controller for a loom, with a comparing means for a measuring quantity related to the warp tension, and a reference quantity, which through an operational amplifier connected as a PI-controller, with in the feedback circuit a resistor parallel to an integrating capacitor, controls an adjusting means for the warp tension, with a voltage memory, the input of which is connected to the output of the operational amplifier, as well as an automatically operated switch which upon switching-off the loom drive, switches the intergrating capacitor from the output of the operational amplifier to the output of the voltage memory.
Warp tension controller for a loom, with a comparing means for a measuring quantity related to the warp tension, and a reference quantity, which through an operational amplifier connected as a PI-controller, with in the feedback circuit a resistor parallel to an integrating capacitor, controls an adjusting means for the warp tension, with a voltage memory, the input of which is connected to the output of the operational amplifier, as well as an automatically operated switch which upon switching-off the loom drive, switches the intergrating capacitor from the output of the operational amplifier to the output of the voltage memory.
Description
The present invention relates to a warp tension controller for a weaving l.oom, with a comparing means Eor a measuring quantity rela~ed to the warp tension and a reference quantity, which through an operational amplifier connected as a PI-controller, witn in the feedback circuit a resistor parallel to an integra-ti.ng capacitor, controls an adjusting means for the warp tension.
Since in a weaving loom,the warp tension varies not only at short term ~y the shaft movements, bu~ al.so varies at long term by the nature of the warp yarn which is handled, the decreasing diamet.er of the warp beam and other circumstances, whereas for a goc~ quality of the fabric, the warp tension must be maintained as ccnstant ns possible, modern looms make use of automatic warp Jtension controllers, comprising a servo loop in which a senso for the warp tension, a reference adjusting means, a com~aring means for the output signals of these two, an operational amplifier and a control means are connected The control means usually aLfects the drive speed of the warp beam, and ~or obtaining a smooth and stable control, the controller is usuall.y designed aa a PI controller, i.e. a con-trol.leY w.ith proportional as well as integratins action/ for which purpose tlle feedback clrcuit of the operational amplifier compr.ises a resistor as well as a capa-itor. The integrating part oE the operation of the operational am~lifier ensures that the warp tension control hardly responds at all to the rapid Eluctuations of the warp tension, caused by the shaft movements, which fluctua-tions are too fast for succesful mechanical compensation by the warp tension control.
''. . ' , 1, ".,' r ,,, ~ ' :
' .
During operation, the integrating capacitor in the Eeedback circuit carries a D ~C. voltage corresponding to the average-output sigrlal of the operational ~mplifier with is required.
If tne loom is stopped, an entirely different condition of the warp yarn is ob-tained mechanically, dependent upon the arbitrary position in which the loom comes to a standstill, 50 that the D.C. voltage across the integrating capacitor assumes a totally differen-t value than during operation.
Nevertheless, as soon as possible, àfter starting up, the original D.~. voltage across the integrating capacitor should again be reached, in order that Ihe condition of normal operation be regained as soon as possible.
The invention aims at providing a solution for this problem.
For that purpose, a warp tension controller according to the invention is characteri~ed by a voltage memory t the input of which is connected to the output of the operational amplif.ier, as w~ll as an automatically operated switch which upon disconnecting the com drive, switches the integrating capaci.tor from the output of the operat onal amplifier to the output of the voltage memory.
The voltage memory stores the output vol~age of the operational amplifier whi.ch existed just prior -to swi.tching the lcom off~ By connecting the integrating capacitor to the ou-tput of the voltage memory during standstill, rather than to the output of t-he o~erational amplifier, the D.C. voltage across the in-tegratin~
capacitor, after standstill oE the loom is no ].onger ef:Eected by the voltage prevailing at the output of the operational ampliEier, which is determined by the condition during standstil:L, rather than by the normal operating condition, but by the output voltage memory, whicn represents the normal. operation condition.
', , ~ . '': ' ', ,' ; , . ' :
~5~6~
When upon restarting the loom, the integrating capacitor is switched bac~ from -the outpu-~ of the -voltage memory -to the output of the operational amplifier, it from the very start carries the correct D.C~ voltage, so that the stable condition of the control is reached very fast.
Tha voltage memory can exist e.g. of an adjustable vol-tage divider which is operated by a servo motor or oE a reference voltage, the servo loop being so designed that the voltage derived at the tap of the adjustablè voltage divider due to the action of the servo motor always equals the output voltage of the operationale amplifier, the position of the adjustable voltaga divider being locked as soon as the loom is switched off.
The invention is further elucidated below with reference to .he drawing, which represents a circuit diagram of an ernbodiment of a warp tension Fontroller according to the invention.
In the figure, the output signal of a warp tension sensor through the input 1 and the output signal of a reference source through an input ~ are applied to a comparing means 3, the output of which is connected to the inverting input of an operational amplifier 4 of the warp tension control loop, which provides its output signal at the tenninal 5. The operational amp:lifier ~ is provided with a feedback network comprising the resistors 6 and 7 and the capacitor 8. The resistors 6 and 7 together determine tha gain of the operational arnplifier at very low frequencies and from a first change-over frequ~ncy, the gain falls due to the integrating capacitor 8, again becoming constant at a lower value at a second change-over frequency, due to the presence of the resistor 7.
The output side of the integrating capacitor through a terminal 9 is connec-ted with the input oE the voltage memory (not shown), the out~ut of which is connected to the terminal 10. As soon as the loom is switched off, the ganged switches 11 and 12 are operated automatically, whereby the integrating capacitor 8 is disconnec-ted from -the feedback circuit (so that the operational amplifier 4 now operates as a pure proportional controller, rather than a proportional and integrating controllerl and its output side through the resistor 13 is connec-ted to the output 1~ of the voltage memory. Since at the output 10 of the voltage memory the voltage remains which immediately prior to the cwitching-off of the loom exis-ted at the input 9 of the voltage memoxy, the ~ntegrating capacitor 8 inde~initely xemains charged :~.. ..
to the voltage which existed immediately prior to switching-off of the loom. As long as the loom remains switched-off, the switcr. 12 connects a resistor 1~ parallel to the resistor 6 from th feedback ^ircuit, whereby the gain of the operational ampl.Lier 4 is lower than during operation~
As soon ag the loom is again swi.tched on, the switches 11 and 12 are automatically returned to the position shown, which res.oxes the feedback cixcuit to the initial condition, the integrating capacitor 8 from the very beginning carrying the correct voltage, so that the control starts with the correct ir.itial conditions.
The ganged switches 15 and 16 and the resistor 17 serve exclusively for slowly turning the loom, e.g. after a new warp beam has been put on and the ends of the warp yarns of that new warp beam have been knotted to the warp yarns of the woven fabric.
Under all other circumstances, the swi-tches 15 and 16 remain in the position shown.
' ', ~. ' '' , ' ' ', ;'"', , ~
Since in a weaving loom,the warp tension varies not only at short term ~y the shaft movements, bu~ al.so varies at long term by the nature of the warp yarn which is handled, the decreasing diamet.er of the warp beam and other circumstances, whereas for a goc~ quality of the fabric, the warp tension must be maintained as ccnstant ns possible, modern looms make use of automatic warp Jtension controllers, comprising a servo loop in which a senso for the warp tension, a reference adjusting means, a com~aring means for the output signals of these two, an operational amplifier and a control means are connected The control means usually aLfects the drive speed of the warp beam, and ~or obtaining a smooth and stable control, the controller is usuall.y designed aa a PI controller, i.e. a con-trol.leY w.ith proportional as well as integratins action/ for which purpose tlle feedback clrcuit of the operational amplifier compr.ises a resistor as well as a capa-itor. The integrating part oE the operation of the operational am~lifier ensures that the warp tension control hardly responds at all to the rapid Eluctuations of the warp tension, caused by the shaft movements, which fluctua-tions are too fast for succesful mechanical compensation by the warp tension control.
''. . ' , 1, ".,' r ,,, ~ ' :
' .
During operation, the integrating capacitor in the Eeedback circuit carries a D ~C. voltage corresponding to the average-output sigrlal of the operational ~mplifier with is required.
If tne loom is stopped, an entirely different condition of the warp yarn is ob-tained mechanically, dependent upon the arbitrary position in which the loom comes to a standstill, 50 that the D.C. voltage across the integrating capacitor assumes a totally differen-t value than during operation.
Nevertheless, as soon as possible, àfter starting up, the original D.~. voltage across the integrating capacitor should again be reached, in order that Ihe condition of normal operation be regained as soon as possible.
The invention aims at providing a solution for this problem.
For that purpose, a warp tension controller according to the invention is characteri~ed by a voltage memory t the input of which is connected to the output of the operational amplif.ier, as w~ll as an automatically operated switch which upon disconnecting the com drive, switches the integrating capaci.tor from the output of the operat onal amplifier to the output of the voltage memory.
The voltage memory stores the output vol~age of the operational amplifier whi.ch existed just prior -to swi.tching the lcom off~ By connecting the integrating capacitor to the ou-tput of the voltage memory during standstill, rather than to the output of t-he o~erational amplifier, the D.C. voltage across the in-tegratin~
capacitor, after standstill oE the loom is no ].onger ef:Eected by the voltage prevailing at the output of the operational ampliEier, which is determined by the condition during standstil:L, rather than by the normal operating condition, but by the output voltage memory, whicn represents the normal. operation condition.
', , ~ . '': ' ', ,' ; , . ' :
~5~6~
When upon restarting the loom, the integrating capacitor is switched bac~ from -the outpu-~ of the -voltage memory -to the output of the operational amplifier, it from the very start carries the correct D.C~ voltage, so that the stable condition of the control is reached very fast.
Tha voltage memory can exist e.g. of an adjustable vol-tage divider which is operated by a servo motor or oE a reference voltage, the servo loop being so designed that the voltage derived at the tap of the adjustablè voltage divider due to the action of the servo motor always equals the output voltage of the operationale amplifier, the position of the adjustable voltaga divider being locked as soon as the loom is switched off.
The invention is further elucidated below with reference to .he drawing, which represents a circuit diagram of an ernbodiment of a warp tension Fontroller according to the invention.
In the figure, the output signal of a warp tension sensor through the input 1 and the output signal of a reference source through an input ~ are applied to a comparing means 3, the output of which is connected to the inverting input of an operational amplifier 4 of the warp tension control loop, which provides its output signal at the tenninal 5. The operational amp:lifier ~ is provided with a feedback network comprising the resistors 6 and 7 and the capacitor 8. The resistors 6 and 7 together determine tha gain of the operational arnplifier at very low frequencies and from a first change-over frequ~ncy, the gain falls due to the integrating capacitor 8, again becoming constant at a lower value at a second change-over frequency, due to the presence of the resistor 7.
The output side of the integrating capacitor through a terminal 9 is connec-ted with the input oE the voltage memory (not shown), the out~ut of which is connected to the terminal 10. As soon as the loom is switched off, the ganged switches 11 and 12 are operated automatically, whereby the integrating capacitor 8 is disconnec-ted from -the feedback circuit (so that the operational amplifier 4 now operates as a pure proportional controller, rather than a proportional and integrating controllerl and its output side through the resistor 13 is connec-ted to the output 1~ of the voltage memory. Since at the output 10 of the voltage memory the voltage remains which immediately prior to the cwitching-off of the loom exis-ted at the input 9 of the voltage memoxy, the ~ntegrating capacitor 8 inde~initely xemains charged :~.. ..
to the voltage which existed immediately prior to switching-off of the loom. As long as the loom remains switched-off, the switcr. 12 connects a resistor 1~ parallel to the resistor 6 from th feedback ^ircuit, whereby the gain of the operational ampl.Lier 4 is lower than during operation~
As soon ag the loom is again swi.tched on, the switches 11 and 12 are automatically returned to the position shown, which res.oxes the feedback cixcuit to the initial condition, the integrating capacitor 8 from the very beginning carrying the correct voltage, so that the control starts with the correct ir.itial conditions.
The ganged switches 15 and 16 and the resistor 17 serve exclusively for slowly turning the loom, e.g. after a new warp beam has been put on and the ends of the warp yarns of that new warp beam have been knotted to the warp yarns of the woven fabric.
Under all other circumstances, the swi-tches 15 and 16 remain in the position shown.
' ', ~. ' '' , ' ' ', ;'"', , ~
Claims
1. Warp tension controller for a loom, with a comparing means for a measuring quantity related to the warp tension, and a reference quantity, which through an operational amplifier connected as a PI-controller, with in the feedback circuit a resistor parallel to an integrating capacitor, controls an adjusting means for the warp tension, characterized by a voltage memory, the input of which is connected to the output of the operational amplifier, as well as an automatically operated switch which upon switching-off the loom drive, switches the integrating capacitor from -the output of the operational amplifier to the output of the voltage memory.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL7502247A NL7502247A (en) | 1975-02-25 | 1975-02-25 | CHAIN TENSION REGULATOR. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1052460A true CA1052460A (en) | 1979-04-10 |
Family
ID=19823256
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA241,776A Expired CA1052460A (en) | 1975-02-25 | 1975-12-15 | Warp tension controller |
Country Status (10)
| Country | Link |
|---|---|
| JP (1) | JPS5199156A (en) |
| BR (1) | BR7508591A (en) |
| CA (1) | CA1052460A (en) |
| CH (1) | CH607774A5 (en) |
| DE (1) | DE2555985A1 (en) |
| FR (1) | FR2302365A1 (en) |
| GB (1) | GB1526968A (en) |
| IN (1) | IN145938B (en) |
| IT (1) | IT1054767B (en) |
| NL (1) | NL7502247A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4332352A (en) * | 1981-01-30 | 1982-06-01 | Honeywell Inc. | Multistage thermostat using integral initiation change means |
| JPH0694614B2 (en) * | 1983-02-25 | 1994-11-24 | 津田駒工業株式会社 | Electric loom feeding method and device |
-
1975
- 1975-02-25 NL NL7502247A patent/NL7502247A/en not_active Application Discontinuation
- 1975-12-12 CH CH1618075A patent/CH607774A5/en not_active IP Right Cessation
- 1975-12-12 DE DE19752555985 patent/DE2555985A1/en not_active Ceased
- 1975-12-15 CA CA241,776A patent/CA1052460A/en not_active Expired
- 1975-12-15 GB GB51289/75A patent/GB1526968A/en not_active Expired
- 1975-12-16 IN IN2344/CAL/75A patent/IN145938B/en unknown
- 1975-12-23 FR FR7539457A patent/FR2302365A1/en active Granted
- 1975-12-23 BR BR7508591*A patent/BR7508591A/en unknown
- 1975-12-27 JP JP50155912A patent/JPS5199156A/ja active Pending
-
1976
- 1976-01-09 IT IT19150/76A patent/IT1054767B/en active
Also Published As
| Publication number | Publication date |
|---|---|
| FR2302365B3 (en) | 1980-06-27 |
| FR2302365A1 (en) | 1976-09-24 |
| BR7508591A (en) | 1976-08-24 |
| NL7502247A (en) | 1976-08-27 |
| DE2555985A1 (en) | 1976-09-02 |
| IT1054767B (en) | 1981-11-30 |
| JPS5199156A (en) | 1976-09-01 |
| GB1526968A (en) | 1978-10-04 |
| IN145938B (en) | 1979-01-20 |
| CH607774A5 (en) | 1978-10-31 |
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