Bimba Model PCS Pneumatic Motion Control System Operating Manual Please read this manual carefully before implementing your Pneumatic Control System. www.bimba.
General Warnings and Safety Guidelines Start by Reading These Important Safety Rules THIS SAFETY ALERT SYMBOL MEANS CAUTION ― PERSONAL SAFETY, PROPERTY/FIXTURING DAMAGE, OR DANGER FROM ELECTRICAL SHOCK. READ INSTRUCTIONS WITH THIS SYMBOL CAREFULLY. READ ALL INSTRUCTIONS CAREFULLY BEFORE INSTALLATION. SAVE THIS MANUAL FOR FUTURE REFERENCE. IF ACTUATOR BECOMES JAMMED, DISCONNECT ALL COMPRESSED AIR CONNECTIONS TO THE ACTUATOR BEFORE ATTEMPTING TO RELEASE OR REMOVE JAMMED ITEM.
Table of Contents General Overview ................................................................................................... Page 4 Typical Applications ................................................................................................ Page 5 Glossary of Terms and Formulas ............................................................................ Page 5 Installation Instructions ............................................................................................ Page 9 1.
General Overview The Bimba Pneumatic Control System (PCS) is a closed loop electronic controller with pneumatic valves that can move the rod or shaft of a pneumatic position feedback actuator and hold it in any desired position with accuracy and force. The PCS system is designed for series PFCN, PFCNL, PFC, and PFCL cylinders for linear motion and the Position Feedback Pneu-Turn (PTF) for rotary motion.
Typical Applications The PCS system is ideal whenever increased flexibility and adaptability is needed in a process; for example, in order to accommodate various size parts and assemblies, or to add control for improved consistency, quality, and productivity. Typical applications are listed below. Flow Gate The PCS system can control the position of a flow gate, controlling the rate of product that flows to downstream processes.
SPAN (Full Scale Position) When the PFC rod is fully extended or the PTF shaft is rotated fully clockwise (CW), it will reach a mechanical stop, due to either a mechanical limit in the application or the actuator’s end of stroke or rotation. The PCS’ Span adjustment allows you to adjust the position of the cylinder at 10 VDC control voltage input. Adjustment range is from the fully extended mechanical limit to approximately 50% of the full actuator stroke or rotation.
FEEDBACK SIGNAL The feedback signal is a voltage signal from the actuator that corresponds to the displacement or rotation of the actuator. The feedback signal range is approximately 0 - 10 VDC. PTF Note: The PTF has a fixed electrical rotation span of 340 degrees. This will affect some of the following adjustments and signals for PTF’s with full scale rotations of less than 180 degrees. DEADBAND The Deadband is a bi-directional band, centered on the commanded position.
The following formula will translate the voltage reading into the Decel Range. DR = 0.01485 * V * t Where: DR = decel range V = voltage reading from the PCS t = full scale travel of the actuator (Note: for PTF rotary actuators with total rotation less than 180º, always make t = 180) Example 1: If the Decel Range is set to 5 volts for an 8 inch stroke cylinder, then deceleration will occur for 0.60 inches (0.0149 * 5 * 8).
Installation Instructions Before installing your system, refer to the Application Sizing and Rules of Thumb section to ensure your system is sized properly for your application. Use the following steps to successfully install and operate your PCS system. There are a couple of application examples that follow this section which are helpful in gaining a full understanding of the adjustments that will be made. 1.
The following table shows recommended tubing sizes. Oversized tubing will degrade positioning repeatability. Bore Size PFC 1-1/16" (09) 1-1/2" (17) 2" (31) PTF 1-1/2" (098/196) 2" (247/494) Tubing Size 5/32" OD 5/32" OD 1/4" OD Air line connections are described in the illustrations below. Instructions follow. Also consult the Appendix for air and electrical connections to PFCN, PFC, and PT.
For best positioning results, consider using a precision relieving regulator and an air reservoir with a check valve before the regulator to ensure that there are no pressure drops to the PCS system. You may want to install mufflers into the exhaust ports of the valve manifold (the two outer ports). This will make the system quieter during operation. Do not to use mufflers with low flow rates; that may slow the actuator. 4. CONNECT THE POWER CABLE Standard Enclosure Carefully remove the enclosure cover.
Option Q Connect the Quick Connect power cable (2 meter model PCS-CBL-PWR or 5 meter Model PCS-CBL-PWR-X) to power. Connect the other end of the cable using the following color codes: +24 VDC-Brown, Ground-Blue, the other wires are not used.
Accessory cable C5/C5X is required for PFC’s with the plug connector option (Option-P quick connect option), and for PTF’s on which a connector is standard). Option-N Connect the shielded feedback cable to terminal block TB2 on the PCS PC Board, allowing for proper strain relief. Follow the same wire color designation defined in the table from the previous section.
Option-N Connect the individual wires from the Command Cable to PCS Terminal Block TB4 on the PC Board per above. Provide the proper strain relief. Option-Q Connect the quick connect command cable (2 meter Model PCS-CBL-CMD or 5 meter Model PCS-CBL-CMD-X) connector end of the cable to the enclosure box command signal connector (this is the 6 pin connector, the connector is keyed and can only be plugged into the correct connector).
Measure the voltage with a digital voltmeter at Terminal Block TB1 on the PCS PC Board. The voltage must be between 23.5 VDC and 24.5 VDC for the system to function properly. 10. APPLY PNEUMATIC PRESSURE Ensure the actuator is clear of all obstacles. Apply a low pneumatic pressure (20 psi). The actuator should attempt to move. If no command signal is applied to the PCS, the cylinder will attempt to assume its zero position.
12. COMMAND THE BIMBA ACTUATOR TO ITS ZERO POSITION We will command the PCS to move to different positions by adjusting the command signal input to TB4. First command the PFC cylinder or the PTF rotary actuator to retract to the zero position by setting the analog command input signal to 0 volts or 4 mA, depending on the setting of jumper J01. Either the cylinder will move to its hard stop (either internal or external) or it will move to a point short of that stop.
Note: If the system does not move at all, go back and check all of your connections. For Option-N models, be sure the valve cables are connected properly. If the wires are reversed, the actuator may move opposite of the intended direction. (i.e., zero will move the actuator to its full scale position. If the actuator does this, reverse the white wires from the valve cables.) Also - If the LED’s occasionally pulse on, it may indicate a slight leak in the system.
14. PRELIMINARY “SPAN” ADJUSTMENT PFC cylinders and PTF rotary actuators greater than 180 degrees of rotation (See below for PTF’s less than 180 degrees) Use the Span adjustment to set the intended fully extended position to be the same as the full scale (maximum) analog command input signal. Using the Main Control (or equivalent), command the actuator to go to the analog command input signal full scale position. (Set the analog command input signal to 10 volts, or 20 mA depending on the PCS Model.
LED goes off. (If the Span potentiometer was adjusted too far and the actuator moved, adjust the Span potentiometer CCW just enough to move the actuator back to the full scale position. If adjusted too far, the Green LED will come back on). Both LEDs should be off when set correctly. This ends the preliminary Span adjustment. If neither LED is on - (Span is currently set somewhere in mid-stroke.) Slowly adjust the Span potentiometer CCW to move the actuator rod or shaft toward the full scale position.
Note: Decel and Deadband adjustments are iterative, and optimum settings depend upon the application and load. Set the deadband as low as possible for the greatest positioning accuracy. Set the Decel as low as possible for the greatest speed. As load inertia increases, the actuator might oscillate (buzz) around the ending position before coming to a complete stop at the commanded position.
17. APPLICATION EXAMPLES PFC Example Suppose we have just finished the installation procedure for a Bimba PFC Cylinder with 10 inches of stroke, and are using a 0-10 VDC input command signal. There is a retracted hard stop at 1.5 inches of cylinder stroke and an extended hard stop at the 9.0 inches of cylinder stroke. Therefore: • • After adjusting the Span setting, 10 volts is equivalent to 9.0 inches of cylinder rod extension. After adjusting the Zero setting, 1.
SPECIFICATIONS Description Specification 50% of Total Full Scale Output between both adjustments Zero Adjustment Span Adjustment DECEL Adjustment Deadband Adjustment @ Position Approximately 0.5 to 13.5 volts Approximately 0.005 to 0.500 Volts Discrete signal that Sinks to Ground when Within Deadband zone. 20mA Maximum. 0 to 10 VDC signal, 1M ohm input impedence required for input device. All valves close at power loss. 23.5 to 24.
• • • • • • • 80 psi air supply. Minimum of 23.5 VDC provided to the PCS. Clean Command Signal for Main Control. (<5mV noise/ripple) Leak free system (The system will actually perform well with some system leakage, however, the best performance is with no leakage). Short (<18 inches), hard air lines (nylon) between the valves and the actuator. No backlash in the system. Horizontally guided load.
Troubleshooting The following information is helpful if you experience difficulties setting up your Pneumatic Control System. A problem may be associated with one or a combination of causes, including a malfunction of your Main Control (PLC), system adjustments, application parameters, or system inputs (air supply, electrical power, command signal, etc.). Try the following suggestions to isolate and solve the problem.
Problem: Solution: The change in command signal is too small. Ensure that the change in command signal is large enough to cause the actuator to move outside of the deadband. If the change in signal is too small (smaller than the adjusted deadband), the actuator will not respond. Problem: Solution: The Zero adjustment is too high and/or Span adjustment is too low. Refer to the Installation Section of the manual that pertains to the Zero and Span Adjustments and make the proper adjustments.
Problem: Solution: Excessive air leak in the actuator or PCS system. Find and fix the leak. External fitting leaks are relatively easy to find. Use a solution, such as Leak Tech, to identify leaks in fittings, couplings, and rod seal (if linear actuator). Check for leaks in the actuator seals. Problem: Solution: PCS valves are contaminated. Unfiltered air (>5 microns) can cause the valves to become contaminated causing them to leak. Use a filter that is rated for <5 micron particles.
Problem: Solution: Air lines between the actuator and PCS valves are too long. Longer air lines cause the system to be less accurate or respond slower. Always use the shortest possible lines as possible (<18"). The system will work with longer lines, but may not be repeatable enough for application requirements. Option N allows you to mount the valves close to the actuator with the PCS electronics mounted separately. Problem: Solution: Air Supply pressure is too low (below 70 psi).
Poor Positioning on the First Cycle Problem: Solution: Air pressure may have been lost during idle time, either through leaks or disconnect of the air supply. If extended periods of non-operation are normal, the application will require a start-up routine for the initial cycle. This will stabilize pressures in the actuator. Repeatability/Stability/Responsiveness changes over time Problem: Solution: Input pressure has changed. Changes in input pressure will effect actuator performance.
Solution: Provide an analog 0-10 VDC command signal that has less than 5 mV of ripple. Employ proper wiring techniques to ensure signal noise is kept to a minimum (use shielded cables, proper grounding methods, etc.) Problem: Solution: The actuator feedback has excess signal noise. Ensure that the feedback signal is free from electrical noise. ElectroMagnetic Interference (EMI) can couple to the feedback signal. Employ shielded cable between the actuator and the PCS system.
APPENDIX A PFC ELECTRICAL AND PNEUMATIC CONNECTIONS www.bimba.
Always insert a jumper between TB1 ground and TB2 terminal C, as shown by the dotted blue line to the right. Note that for the PFCN, power to the probe MUST come from 24 VDC supplied to the PCS control, and NOT the 10 VDC that the PCS produces from terminal A of TB2. If the Q (quick connect) option was selected, the connection to terminal A of TB2 must be removed and the lead reinserted into the +24VDC terminal of TB1. Also, insert a jumper between TB1 ground and TB2 terminal C (dotted blue line).
PT ELECTRICAL AND PNEUMATIC CONNECTIONS Note: For Single Rack Models, Use Only Bodies “A” and “B.” www.bimba.
APPENDIX B PFC Probe Replacement Instructions 1. Using the correct allen wrench identified in the table below, remove the four socket head cap screws on the rear of the cylinder. Bore 09 17 31 50 70 Wrench 3/32 3/32 5/32 3/16 1/4 2. Remove the rear cap. If a plug connector is installed in the rear cap, slide it out. 3. Using a 3/8 inch wrench, carefully unscrew the exposed delrin nut (the back end of the probe). When all the threads are free, pull the probe out of the cylinder.
4. Gently insert the replacement probe into the cylinder, rotating it until it slides through the hole in the piston. DO NOT FORCE THE PROBE INTO THE CYLINDER. It should slide in freely with minimal friction. Hand tighten until O-ring is seated, then rotate ONLY ¼ turn until with the ¼ inch wrench. APPLYING TOO MUCH TORQUE WILL DAMAGE THE PROBE. 5. If there is a plug connector, slide it into the area in the rear cap. 6. Replace the rear cap and four cap screws using the torque in the table below.
APPENDIX C PFCN Probe Adjustment and Replacement Instructions Probe Adjustment Probe output calibration is normally not required. Every PFCN is calibrated at the factory for 0 to 10 V DC output fully retracted to fully extended. If readjustment is necessary in your application, follow the instructions below: 1. Install the PFCN in your application. Remove the rear end cap exposing the probe and four adjustment screws. 2. Apply 24 VDC power to the probe and monitor the feedback voltage.
Bimba Manufacturing Company Monee, Illinois 60449-0068 TEL: 708-534-8544 • FAX 708-534-5767 Visit our Web Site at: www.bimba.com For Technical Assistance: 800-44-BIMBA Manual PCS-1008-A www.bimba.
