What is load cell ? How it works ? thanks

[phatcreators]

I show you : How to use datasheet and make test circuit ?

Your datasheet.............................
**broken link removed**

Look installation...........
View attachment 63797

Measured force direction vertical downwards.

Look Schematic and electrical data.....................
View attachment 63798

If measured with ohm-meter >> Gage Resistance: 350 ohm

Making test circuit....................

Excitation Voltage: 10 Vdc nominal
Output Signal: 21 mVdc nominal per load cell at full load rating

Cable Connector: PT01P-10-6P-SR; MAGPOWR mating cable assembly
part number SC15, or mating connector 12A36-1
(pin A, + power; pin B, + signal; pin C, -signal; pin D, -power)

That is all you need, now make circuit for testing................
View attachment 63799

Look force you need for test....................
View attachment 63800

You find out GTSA50M >> 50 kg = full load >> then Output Signal: 21 mVdc nominal

So when vertical force down is 50 kp then meter should read 21 mV
25 kp >> 10.5mV ; 12.5 kp >> 5.25mV .... etc.

And everything found on datasheet, i think : it was not so hard.

Regards KAK

thanks KAK,

Question regarding the printing machinery " Doubaut Printing Machinery (china) "

**broken link removed**

Doubaut Printing Machinery Co., Ltd. - Company Home - China Service Company

There are unwind rollers, Rewind rollers, infeed dancing rollers & outfeed dancing rollers.

The problem is that the machine is not printing the film (web) properly. The pots are connected to all the four unwind rollers (shafts), Rewind rollers (shafts), infeed dancing rollers (shafts) & outfeed dancing rollers (shafts).

5 Kohms pot are there, each pot is in contact with their respective roller with the grooves present on the end of the respective rollers and also a groove covering on the knob of the pot (which is being tightened by the Allen bolt or Hex Bolt).

The dancing rollers dance (move) with the help of Air, the air is controlled manually. You can set or adjust the air as you want.

potentiometers outputs is going to the PLC and the output of the PLC is going into the Inverter & from inverter to the motor.

The Pot. generate 10 V DC output to the PLC ......

The problem is that the infeed dancing roller is not in its normal position where it should be to provide the proper required tension to the film (web) ... its going down towards the left side more ..... I've checked the pot. its fine , tried to adjust the air pressure , checked the inverter its not showing any alarm or any warning neither its stopping ......

what to do ? Any idea ...... thanks

 

[kak111]

I quess system is somenthing like this............



What is the principle the dancer rollers tension measure ; is there swing arm for sensing angle with pot.meter or ????

Anyway it seems that infeed roller is not in right angle compared to web line
(and) or pot.meter zero offset is not right. ( is pot.meter mechanically in right position). Then measuring roller is not right position.
Can be mechanical fail in bearings, fixing parts are not ok or some reason moving assembly is too heavy to move.

First try to find out , why web-line is not perpendicular to roller.
If there is brake in infeed, check brake adjustment and braking force and brake control action with PLC control signal
Check is pot.meter zero offset correct. and Pot.meters do not have dead zones , ie. points where signal suddently jumps. (Bad contact inside pot. )
Careful check all mechanics in control system, everything can move freely ( non stuck parts).
Check is there any bad or broken wires or bad contacts.
I hope somebody have not change any PLC parameters for web control

You should show me , how the measure and control system is mechanically done and exact machine electric block diagram for machine control,
for better analyze and advices.

KAK

 

[phatcreators]

I quess system is somenthing like this............



What is the principle the dancer rollers tension measure ; is there swing arm for sensing angle with pot.meter or ????

Anyway it seems that infeed roller is not in right angle compared to web line
(and) or pot.meter zero offset is not right. ( is pot.meter mechanically in right position). Then measuring roller is not right position.
Can be mechanical fail in bearings, fixing parts are not ok or some reason moving assembly is too heavy to move.

First try to find out , why web-line is not perpendicular to roller.
If there is brake in infeed, check brake adjustment and braking force and brake control action with PLC control signal
Check is pot.meter zero offset correct. and Pot.meters do not have dead zones , ie. points where signal suddently jumps. (Bad contact inside pot. )
Careful check all mechanics in control system, everything can move freely ( non stuck parts).
Check is there any bad or broken wires or bad contacts.
I hope somebody have not change any PLC parameters for web control

You should show me , how the measure and control system is mechanically done and exact machine electric block diagram for machine control,
for better analyze and advices.

KAK

Yes. " How the dancer rollers measure tension ; is there swing arm for sensing angle with pot.meter or ????

" . Yes you're right

How to check pot. meter zero offset is correct ?

In the figure , why didn't you take unwinding shafts & rewinding shafts ?

1) Unwinding shaft
2) Infeed dancing reel
3) Outfeed dancing reel
4) Rewinding shaft (roller)

these are four (4) components which are important to this process ....... in the same order as i mentioned them just above .....

How to test/check brake adjustment and braking force and brake control action with PLC control signal ?

There's an external braking unit is attached , but i don't know if it has any impact or effect to what you're talking above " brake adjustment and braking force and brake control action with PLC control signal ".

How to check or how to get to know that " infeed roller is not in right angle compared to web line " ?

Siemens S7-200 CN PLC CPU is there with expandable modules : EM 235 CN, EM 232 CN & EM 222 CN ?

What about these modules EM 235 CN, EM 232 CN & EM 222 CN ?

What are their inputs & What are their outputs ? Analog or Digital ?


thanks a lot

---------- Post added at 20:38 ---------- Previous post was at 20:09 ----------

Don't you think that the frequency (speed) of all the inverters should be equal so that the tension on the web remains fine ?

Don't you think that all the inverters used, should be of same manufacturer (like we have 4 Yaskawa's inverter & 1 inverter is of Mitsubishi FreqRol A-500 for the Rewinding shaft) ?

Why there's a bigger (larger) inverter used in this process (It has the external Braking Unit) ?

Wire having code " AC " is connected to M0 (printed on the PLC module) & " A " is connected to V0 ..... Where AC is " Analog Common i.e. 0V " & A is " Master Speed Reference 0 to +10V (-10V to +10V) " and these are two are coming from the pots. of all the 4 components (output or reference voltage of pot.) and then the output of PLC is going into their respective inverters.

What does it mean by MO or M0 & VO or V0 ?

thanks a lot

 

[kak111]

How to check pot. meter zero offset is correct ?

This means angle of dancer-swing arm when pot.meter signal value that is corresponding to the zero control for PLC.
These values should be found in service manuals of control system.
(This means that changing angle position of the pot in arm mounting, the control system change angle position of the arm
during machine run.)

How to test/check brake adjustment and braking force and brake control action with PLC control signal ?

there are two principle for web tension control:
1. set arm opposing force manually (in this machine with air-pressure) and control web-brake with PLC
2. set brake force manually and control web-tension with PLC and motor inverter ( by controlling speed of drive motor).
- angle of the swing-arm with potentiometer measure web-tension for plc control

System can be used in infeed or outfeed

opposite system has brake instead motor (running from right to left) ( most left roller is unwinding )

How to check or how to get to know that " infeed roller is not in right angle compared to web line " ?

-it depends, how web cross position (sideways) is controlled in maschine.
( control with unwinding roll cross position or with changing cross angle in some roller)

What about these modules EM 235 CN, EM 232 CN & EM 222 CN

Analog module EM 235 page 45...
Analog module EM 232 page 44...
Digital module EM 222 page 30...
**broken link removed**

 

[phatcreators]

This means angle of dancer-swing arm when pot.meter signal value that is corresponding to the zero control for PLC.
These values should be found in service manuals of control system.
(This means that changing angle position of the pot in arm mounting, the control system change angle position of the arm
during machine run.)



there are two principle for web tension control:
1. set arm opposing force manually (in this machine with air-pressure) and control web-brake with PLC
2. set brake force manually and control web-tension with PLC and motor inverter ( by controlling speed of drive motor).
- angle of the swing-arm with potentiometer measure web-tension for plc control

System can be used in infeed or outfeed
View attachment 64165
opposite system has brake instead motor (running from right to left) ( most left roller is unwinding )



-it depends, how web cross position (sideways) is controlled in maschine.
( control with unwinding roll cross position or with changing cross angle in some roller)




Analog module EM 235 page 45...
Analog module EM 232 page 44...
Digital module EM 222 page 30...
**broken link removed**

the problem now is that the machine runs perfectly till the speed of 66 m/min , beyond that the same problem starts (the out-feed reel stuck to a position i.e. to the right & digital indicator shows + 9 on the scale from -10 to +10 ) ...... and to keep running on that speed the production losses are crept up ....

I have adjusted or set pot. meter zero offset in such a way that i centred the dancer-swing arm manually with the air pressure and kept the needle on the zero (on digital indicator) by rotating the knob of pot. and then tighten up the grooves of the pot. with the grooves of dancer-swing arm ....... Is it the right way to do the pot. meter zero offset ?

How to control web-brake with PLC ?

Don't you think that the frequency (speed) of all the inverters should be equal so that the tension on the web remains fine ?

Don't you think that all the inverters used, should be of same manufacturer (like we have 4 Yaskawa's inverter & 1 inverter is of Mitsubishi FreqRol A-500 for the Rewinding shaft) ?

Why there's a bigger (larger) inverter used in this process (It has the external Braking Unit) ?

thanks a lot

 

[kak111]

the problem now is that the machine runs perfectly till the speed of 66 m/min , beyond that the same problem starts (the out-feed reel stuck to a position i.e. to the right & digital indicator shows + 9 on the scale from -10 to +10 ) ...... and to keep running on that speed the production losses are crept up ....

Does this mean , that this machine controls web cross-position by moving in-feed and out-feed reels sideways.

I must know exactly, how web cross-position is controlled by mechanically in whole web lenght
(from in-feed reel to out-feed reel and what are the sidewys control mechanical parts )
(what is the structural implementation of cross-position control )

Because what you told above, tells me that when web speed exseeds 66m/min ,
the out-feed reel side-control runs out its operating range.
You must check the positions of all other devices which are depended web side position.

Exact line-up alignment of machine units and reels is very important.

( Is some mechanical or electric repairs done before this fail occurs. ) ( Changed parts, etc....)
Is this fail occurred suddenly or slowly over a longer period by turning worse.

Don't you think that the frequency (speed) of all the inverters should be equal so that the tension on the web remains fine ?

Control system has one master speed signal and it calculates own offset value for every tension depended inverter.
This offset is quite small and it is influenced by the sensors and parameters.
This means that speed command for these inverters varies all the time, when web is running.

Don't you think that all the inverters used, should be of same manufacturer

No. Most important is that they are properly sized and setting the values ​​(parameters) are correct for the motor and control system.

Why there's a bigger (larger) inverter used in this process

Drives are sized for motors and if braking power is high enought, braking unit is needed.

I should find mechanical and electric block diagram for exactly this machine implementations.
Send me exact type and model of the machine. ( year of manufacturing too)
Has the machine any modifications made afterwards.

 

[dineshdeshmuk]

what do you mean by offset value ?

 

[kak111]

what do you mean by offset value ?

Setpoint value for tension depended inverter is master speed set value plus offset value .
Offset is calculated correction value for controlling tension in web

 

[danishdeshmuk]

Which type of control method would you prefer for this web tension controlling process ?

open loop
v/f
flux vector control

thanks

 

[kak111]

An open-loop controller, also called a non-feedback controller, is a type of controller that computes its input into a system using only the current state and its model of the system.

A characteristic of the open-loop controller is that it does not use feedback to determine if its output has achieved the desired goal of the input. This means that the system does not observe the output of the processes that it is controlling. Consequently, a true open-loop system can not engage in machine learning and also cannot correct any errors that it could make. It also may not compensate for disturbances in the system.

This system can not be used for machine WEB tension control

But when talking about motor control

Typical PWM controlled drive is, a V/F drive ie. variable frequency drive (VFD)
These VDF´s can control its output with scalar or vector control model.

Scalar VDF use simple Volt / Frequency table for setting output voltage versus frequency.
Scalar control adjusts the motor speed by varying the output frequency of a frequency converter.
The motor speed is then defined by the frequency and loading torque.
The speed accuracy can be improved by speed feedback (tacho generator) and this system is called for Closed-loop scalar control.

Vector control in VDF use scalar principle and additional it knows rotor slip in different load situations ,
thisway it can add corrective output value to scalar principle and control motor speed and torque more accurate.

"Open Loop" vector drive does this by looking at the motor current reponse and compring that to a previoulsy created mathematical
model of the motor response curves.

"Closed Loop" vector drive knows motors rotor position and what the motor needs because motor has inbuilt shaft encoder
which tells it what is happening immediately.
The stator phase currents are measured and converted into a corresponding complex (space) vector.
This current vector is then transformed to a coordinate system rotating with the rotor of the machine.
For this the rotor position has to be known.

**broken link removed**

 

[phatcreators]

what's the difference in closed loop scalar control & closed loop vector control ?

Also , between open loop scalar control & open loop vector control ?

thanks, KAK

 

[kak111]

You find the differencies by looking these pictures........
Control methods
–Open loop algorithms
–Closed loop algorithms






Here is all the text & pictures ..............
Very good seminar presentation papers

Implementing Embedded Speed Control for AC Induction Motors
http://am.renesas.com/media/products/mpumcu/child_folder/Renesas_Jani_Seminar.pdf

 

[danishdeshmuk]

Which type of control method would you prefer for this web tension controlling process ?

open loop
v/f
flux vector control

thanks

 

[phatcreators]

Setpoint value for tension depended inverter is master speed set value plus offset value .
Offset is calculated correction value for controlling tension in web

Regarding Doubaut (China) Printing machine :

Its a Rotogravure Printing machine,

model : YAD71000F

Serial No. : 8304

Rating : 250 KW

Type : STD

Mfg date : 20 - 4 - 2006

Origin : Guangdong, China

**broken link removed** (but the website is not working anymore, i think)




the unwind motor' inverter has the selection of flux vector control.
the rewind motor' inverter has the selection of open loop vector control.
the infeed motor' inverter has the selection of v/f control.
the out-feed motor' inverter has the selection of open loop vector control.

&

the main motor' inverter has the selection of v/f control.

in which inverters (or motors) the synchronization of the speed (frequency) should be maintained, so that the web tension across all 7 stations remains accurate ?

1) b/w unwind & in-feed
&
2) between (b/w) rewind & out-feed

OR

1) b/w unwind & rewind
&
2) b/w in-feed & out-feed

can we change the frequency controlling method of the inverter(s) in such a way that there's no problem in web tensioning process ?

Also the main motor is starting when the speedometer on the digital screen shows the speed of 5 m/min , although it was starting as the speed increased from 0 to 1 m/min , why is it so ?

thanks a lot ....... looking forward to the replies from all of the guys esp. KAK

 

[dineshdeshmuk]

Which type of control method would you prefer for this web tension controlling process ?

open loop
v/f
flux vector control

thanks

 

[kak111]

I could not find any documents or information about this machine
in order to be able to answer questions,
I need to know the machine structure and see the control block diagram

Do not alter the factory settings, because all the control parameters are dependent on
one another.

 

[danishdeshmuk]

Which type of control method would you prefer for this web tension controlling process ?

open loop
v/f
flux vector control

thanks

 

[phatcreators]

I could not find any documents or information about this machine
in order to be able to answer questions,
I need to know the machine structure and see the control block diagram

Do not alter the factory settings, because all the control parameters are dependent on
one another.

Kak you didn't reply me what i asked above ........ please do reply soon

the unwind motor' inverter has the selection of flux vector control.
the rewind motor' inverter has the selection of open loop vector control.
the infeed motor' inverter has the selection of v/f control.
the out-feed motor' inverter has the selection of open loop vector control.

&

the main motor' inverter has the selection of v/f control.

in which inverters (or motors) the synchronization of the speed (frequency) should be maintained, so that the web tension across all 7 stations remains accurate ?

1) b/w unwind & in-feed
&
2) between (b/w) rewind & out-feed

OR

1) b/w unwind & rewind
&
2) b/w in-feed & out-feed

can we change the frequency controlling method of the inverter(s) in such a way that there's no problem in web tensioning process ?

Also the main motor is starting when the speedometer on the digital screen shows the speed of 5 m/min , although it was starting as the speed increased from 0 to 1 m/min , why is it so ?

thanks a lot ....... looking forward to the replies from all of the guys esp. KAK

 

[danishdeshmuk]

what about magnetic flux vector control ?
In what applications its is used ?

thanks

 

[munzir]

Kak you didn't reply me what i asked above ........ please do reply soon

the unwind motor' inverter has the selection of flux vector control.
the rewind motor' inverter has the selection of open loop vector control.
the infeed motor' inverter has the selection of v/f control.
the out-feed motor' inverter has the selection of open loop vector control.

&

the main motor' inverter has the selection of v/f control.

in which inverters (or motors) the synchronization of the speed (frequency) should be maintained, so that the web tension across all 7 stations remains accurate ?

1) b/w unwind & in-feed
&
2) between (b/w) rewind & out-feed

OR

1) b/w unwind & rewind
&
2) b/w in-feed & out-feed

can we change the frequency controlling method of the inverter(s) in such a way that there's no problem in web tensioning process ?

Also the main motor is starting when the speedometer on the digital screen shows the speed of 5 m/min , although it was starting as the speed increased from 0 to 1 m/min , why is it so ?

thanks a lot ....... looking forward to the replies from all of the guys esp. KAK