One individual claimed vehemently that a pair of VFDs operating on a production line were actually servos, and I took his word for it. How can I utilize Kinetix servos to control a web-like material as if they were VFDs? It's too late to switch gears at this point. In more detail, I am controlling the production of asphalt roofing material. This material consists of a backing made of fiberglass or polymer weave that is saturated and coated with asphalt, polymers, films, sand, and rocks. The production process resembles that of a large, odorous, black printing press. This process occurs towards the end of the line, leading into a winder. Initially, there were two VFD/motors responsible for dropping a large loop into a pit for the subsequent section to pull. The motors would deactivate when a lower photoreceptor is obstructed, and resume operation when an upper photosensor is cleared. These have now been replaced with servos.
Are you worried about a slack loop downstream of the servo motors? And if there is, is the winder situated after the slack loop? Generally, it is beneficial to have servo motors with extra duty cycle and precision capabilities even if they are not always needed, as long as they are appropriately sized for the application.
In a forum discussion, RetiQlum2 claimed that VFDs on a production line were servos, which I initially believed. Now, I am trying to figure out how to utilize Kinetix servos to drive a web-type product like VFDs. The process involves handling asphalt roofing material consisting of fiberglass or polymer weave coated with asphalt, polymers, films, sand, and rock. It resembles a large printing press, leading to a winder where two VFD/motors used to control the material loop. I have now replaced them with servos, bringing about the need for adjustments in operation. The transition to servos on the winder pit requires careful monitoring and setup to mimic the functionality of VFDs accurately. By enabling the axis and using MAJ and MAS commands on Kinetix, the servos can replicate the start/stop mechanism of VFDs. Although there may be additional maintenance tasks such as axis monitoring and fault resets, once properly configured, the system is expected to operate seamlessly.
OkiePC asked if there is still a slack loop located downstream of the servo motors that you should be worried about. If there is, is the winder positioned downstream of the slack loop? Generally, having servos with extra duty cycle and precision capabilities, even if not always necessary, is better than the opposite. The winder would indeed be downstream of the pit. In the setup, there is a Finished Product Looper (FPL), which functions as a large chain accumulator operating at line speed with material accumulated in it. A pull roll follows, feeding into the pit, and then to the winder. Some systems use pits, while others may use shock rolls or free loops with the winder suspended in the air, but the concept remains the same.
For a more advanced setup, consider implementing two bonding mills with flatteners before belt sanders, like we did at my previous workplace. The flatteners were VFD driven, with speed controlled by a tach generator on the main mill motor. A potentiometer adjusted speed based on a dancer arm's angle at the strip exit. Once calibrated, the VFD maintained constant speed for a consistent loop height. If interested, you could try a similar setup or explore MAJ/MAS instructions like @robertmee. While a across-the-line starter may work for stable line speeds, it puts more strain on the motor. Make sure to account for motor service factor and consider using an externally powered cooling fan. Given the availability of VFD/servo drives, it's wise to utilize them for optimal performance.
I partially agree with the recommendation to utilize "MAJ/MAS instructions" for controlling the run/stop functions. Another crucial element to consider is the MCD (Motion Change Dynamics). The MAJ instruction directs the servo to operate at a specific velocity and acceleration, serving as a one-time directive that sets the speed and acceleration parameters when triggered. The servo will continue to run at these set values until a new command is issued. On the other hand, the MCD command is used to adjust the velocity or acceleration of the servo. If there are changes in motor speed due to variations in line speed or feedback from load cells or dancers, continuous MCD commands will be necessary. When operating VFDs in torque control mode, utilizing servos can present added complexity. While it is achievable, servos are typically more focused on velocity and position control. Therefore, adjustments must be made to efficiently run a servo in torque mode without encountering errors related to position or velocity.
While it's true that VFDs and servos differ in their functions, they can still be substituted for one another in certain scenarios. In your case, employing Kinetix servos for controlling web-like material sounds quite feasible. Instead of using speed control as you might with VFDs, you'd use position control offered by servos. The lower and upper photosensors can be analogous to limits within which the servo must maintain the loop. You must calculate the PID parameters accurately and apply a good control strategy to make it work. Remember, precision and control are a servo system's forte, so if handled correctly, it can bring about increased efficiency and accuracy in your production line. Do seek the advice of a controls engineer, if possible.
I can understand the confusion due to the terminology, but it's crucial to differentiate between VFDs and Servos. VFDs (Variable Frequency Drives) are known for controlling the speed of AC induction motors which turn constantly at full speed, while Servo drives offer precise control of velocity, torque, and position, which may be more beneficial for your application. Regarding your situation, you can potentially imitate the functionality of the VFDs by using a PID loop in your Kinetix servos. You could use the position of your loop (based on the engaged or disengaged photoreceptors) as your position feedback, and set bi-directional speed limits based on your desired velocity. This way, you will be able to control the material flow as if it was being regulated by VFDs, but also have the added benefits of precision control offered by the sherovs. Make sure, however, to work with a systems integrator or seek advice directly from Kinetix because tuning new servo systems to match an existing process can be complex and require expertise.
While I understand that switching gears at this point might seem daunting, utilizing Kinetix servos to simulate the operations of a VFD can be done with some careful tuning. I'd recommend utilizing the servo's closed-loop control to replicate what the VFDs were doing. Essentially, you'd have the servo adjust based on inputs from those photoreceptors you mentioned. One key difference is that servos can provide more precision than VFDs, so you might need to tweak the settings to avoid overcompensation or jittery motion. A few rounds of testing and modification should get the job done. Moving forward, remember that while VFDs and servos might seem interchangeable, they are designed for different roles and it's crucial to select the most appropriate one for your specific application.
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Answer: Yes, Kinetix servos can be utilized to control web-like materials effectively.
Answer: Kinetix servos can be programmed and configured to perform tasks similar to VFDs in controlling web-like materials on a production line.
Answer: Kinetix servos offer more precise control and flexibility compared to VFDs, making them suitable for applications involving web-like materials.
Answer: While it may require adjustments and reprogramming, Kinetix servos can be integrated to effectively control web-like materials in production processes previously managed by VFDs.
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