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How to make the logic

Created by: Saravana kumar at: 6/24/2009 3:05 PM (3 Replies)

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6/24/2009 3:05 PM	Rate (0)
Saravana kumar Gold Member Joined: 2/6/2009 Last visit: 4/19/2023 Posts: 932 Rating: (117)	Hi, I am working in one Unwinder Application at a Paper plant. The requirement is to control brake pressure (0 to 5 Bars) of the "Unwinder stand chucks". I am having three depending parametersfor the control of brake. They are, 1. WIndth of the Paper coil(MM) 2. Thickness of Paper (GSM). 3. Diameter of the Paper coil (MM). Please help to find out the formula to get the Brake Pressure ( as Analog Out)to the Unwinder stand chucks by using the above three depending parameter. I tried one methodby taking theaverage percentage of the above three factors, but the brake pressure is notenough. Note : The core Diameter of the Paper coils are 180mm. Maximum Diameter = 1800 mm; Minimum Diameter = 180 mm Maximum Thickness= 500 GSM ; Minimum Thickness = 170 GSM. Maximum Width = 2200mm; Minimum Width = 420 MM.
	Last edited by: saravana kumar@VAES-Bangalore at: 6/24/2009 3:27 PM _______________________________________________________________ Best Regards T.Saravana Kumar "All for the Best"
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6/24/2009 5:07 PM	Rate (0)
SzymekEl Posts: 39 Rating: (3)	<brake Pressure> = a<WIndth of the Paper coil> + b<Thickness of Paper> + c*<Diameter of the Paper coil> where: a, b, c - coefficients If You know right value of breake pressure for three diffrent combination of wIndth of the Paper coil, thickness of Paper and diameter of the Paper coil You can solve system of equations and get a, b and c. Of course everything above is right if dependence between brake pressure and 3 parameters are linear. Regards, Szymon L.
SzymekEl Posts: 39 Rating: (3)
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6/24/2009 5:54 PM	Rate (2)
uel123 Gold Member Joined: 1/29/2006 Last visit: 5/28/2023 Posts: 438 Rating: (62)	saravana kumar@VAES-Bangalore Hi, I am working in one Unwinder Application at a Paper plant. The requirement is to control brake pressure (0 to 5 Bars) of the "Unwinder stand chucks". I am having three depending parametersfor the control of brake. They are, 1. WIndth of the Paper coil(MM) 2. Thickness of Paper (GSM). 3. Diameter of the Paper coil (MM). Please help to find out the formula to get the Brake Pressure ( as Analog Out)to the Unwinder stand chucks by using the above three depending parameter. I tried one methodby taking theaverage percentage of the above three factors, but the brake pressure is notenough. Note : The core Diameter of the Paper coils are 180mm. Maximum Diameter = 1800 mm; Minimum Diameter = 180 mm Maximum Thickness= 500 GSM ; Minimum Thickness = 170 GSM. Maximum Width = 2200mm; Minimum Width = 420 MM. Hey, Kumar! Your task is not very easy. Iam not sure, if proper winding/unwindcan at all be realised without closed loop control: - either dancer-roll position control - eiher actual tension control. For both, you need to measure something (dancer-roll positionor actual tension) and thenprogram a PID control in your PLC. The output of PID can then be your desired break pressure. If you don´t want to use closed - loop control, then you will have to proceed as follows: Some basic formulas: Desired paper force F (N): this thing really depends on paper thicknes and width. It is very important at winding, but not so important at unwinding. I would say, you can define it experimentaly. Desired braking torque (T,Nm): T= Fr; (Desired paper force Actual roll radius) With your pneumatic Brake, you have a direct influence on braking torque.Then, you have to decide about your unwinding strategy. I propose, you go foconstant paper force through all of your unwinding process. Therefore, your desired braking force wouldbasicaly be some linear functionof actual diameter; bigger diameter, biggerbraking force; lower diameter, lower braking force. For characteristics of this linear function, you will have to do some experiments! I propose a following procedure (if you really don´t want to go on closed loop control): Try to make some experiments at different types of paper (different thickness, different width;). Make measurements for different sorts of paper, which brake pressure is good for you at minimum diameter and maximum diameter,..... Then simply write a lienar interpolationcharacteristics for your tipicall paper types..... . Don´t forget to prepair an input, thatsomefast, online correction for thischaracteristics can be made on site! Have fun! uel 123 btw: 1. search the net for winding/unwinding applications! 2. I still strongly reccomend the use of (any!) closed loop control, because brakes tend to change their properties with temperature, time,...... i.e.: it is not sure, that you will get the same braking effect at the same braking pressure in two different days!

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6/25/2009 11:51 PM	Rate (1)
gbs Posts: 178 Rating: (5)	Great post by uel123. I have a number of FC blocksfor unwind control both braked and driven.Inboth applications we use dancer or tension feedback. Hope this primer sheds additional light. Attachment Dancer.pdf (98 Downloads)
gbs Posts: 178 Rating: (5)
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This contribution was helpful to 3 thankful Users fritz UMENCHO Enigma

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