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In 2004, China's servo products were more integrated with dedicated controllers, accounting for nearly 60% of the market. PC is the second largest platform for servo products, accounting for 20% of the market, and PLC is also the main controller of the equipment; However, only a few European manufacturers provide drivers that integrate motion controllers and are used in applications where space requirements are high.
So if the servo system is applied to the packaging production line, what benefits or even innovations will it bring to the motion control system? To this end, three industry experts were invited to discuss the application of servo control in the field of packaging, which led to their respective views and opinions on the development of the technology and the application status at home and abroad, and hope to share with the industry. Thanks to the strong support of the experts.
First, packaging technology promotes the development of servo systems
Although most pharmaceutical manufacturers are quiet about their new equipment, servo power packaging systems still occupy the right place in the factory. When flexible production equipment becomes the backbone of consumer goods manufacturers, the necessary adjustments have become a powerful resistance in pharmaceutical applications.
Bosch Packaging has produced a variety of servo control machines for pharmaceutical manufacturers. The company's director of electronic engineering, David Blau, said, “The pharmaceutical factory has just experienced the benefits of servos – simple changes in production methods make short-term and small-volume production more economical, no need to spend 4 to 6 hours to clean, auto-extinguish Bacteria and changing cams and parts, and in just a few minutes, the machine can be reprogrammed, with different types or sizes of parts to re-run the machine. At the same time, the servo system is simpler, cleaner and less prone to collapse.
Compared with the traditional shaft drive packaging system using PLC control and mechanical connection, the servo system relies on the PC-based control system, which brings more problems. Many pharmaceutical companies prefer to go a long way in using servo devices, especially when they have more specialized drugs that require multiple packages, and pharmaceutical companies are looking for devices that give them more flexibility.
Second, the advantages of the servo system
Mike Wagner, Rockwell Automation's business development, said, "Not to mention commercial pressure, servo-based equipment has more advantages than shaft transmission equipment. Before the servo system, packaging equipment had a big exchange. The motor runs at a fixed speed, and the mechanical connection away from the spindle controls each packaging program, converting the axis motion from one speed to another, or converting the rotary motion into a linear motion. Each time the spindle rotates, it produces from the other end. A product. When you want to change a vial to a large bottle or change the size or shape of the package, you must re-adjust the device."
The servo system changed this situation, without the mechanical connection to the spindle, and each servo system (including the motor, gear head and software) operated independently. The advantage of this is that it can be changed regardless of pressure, speed and position. In the past, it took 7 hours to change these, unless it was large enough to ensure the effectiveness of the adjustment and the ideal production cycle, it would be difficult to change. Now, it takes only 3-5 minutes to complete the adjustment, and the method is simple.
Separate the servo system from the motor drive shaft so that they can independently adjust for each event in the packaging process. Bob Hatavigo, vice president of Pitt, said: "A simple low-to-medium-speed filling line consists of simple devices and a host. All devices depend on each other and work together. Data collection, the servo system on the filling line can independently adjust any production problems that occur." According to John Kwa, global marketing of ELAU in Germany, “The servo system has also increased the speed and accuracy to a whole new level. 70% to 80% of balers, outsourcing machines, container balers, pallets sold to pharmaceutical companies. The stacker will use the servo system."
One of the main features of the servo system is its closed-loop feedback. The accuracy of the servo-based sealer can be controlled to ±0.02%, while the accuracy of the standard clutch-driven sealer is only 20%. The value to the servo system. For example, after storing the torque value for each cover, if a recall is required, only 1000 bottles are recalled instead of the previous 1 million bottles. The same data can also be used to analyze the degree of wear on the sealer to determine if repair is required. Since the servo system uses a smaller motor, it requires very little maintenance. Typically, the interval between two failures of the servo system is 200,000 hours.
Today's servo systems give people a feeling of value that is far more valuable than in the past. Five years ago, a typical servo system cost $10,000. Today, it only sells for $5,000, and prices are still falling. On a machine with a price of $100,000, plus 10 servos, the price will increase by 50%. Correspondingly, adding 10 identical servo systems to a larger machine with a price of $500,000 to $1 million is not obvious, but the rewards are huge.
Third, the lack of servo system
A project of a lingzhi pharmaceutical company said, “They will be faster, more precise, easier to control, repair and use, and more durable. When the original system is to be phased out or a new plant is to be built, it is recommended to install a full servo packaging line. Because the servo system can help predict what happens before the problem occurs, and tell where to solve it. Everything becomes simple and takes a big step forward than the axis-driven machine."
However, the actual application is not the case, the reason is related to servo system control. To understand why, you need to look at the old-fashioned shaft drive packaging line. They may not be flexible or precise, but mechanical connections make them predictable. A programmable logic controller using ladder logic enables one function to follow another function, which is a relatively easy to confirm system.
But at the same time, servo systems are stand-alone modules that rely on software rather than gears, chains and cams to perform their tasks. Many software uses PC-based processors, which are both powerful and vulnerable. On the one hand, personal computers make drag-and-drop and touch screen controls possible. They support advanced data collection, transmission and analysis, as well as the comprehensive requirements for audit audits that are subject to 21 CFR Part 11 regulations. But the downside is that these powerful places are also where the personal computer is vulnerable. Unlike PC ladder logic, a computer can do 10 different things at the same time, so when these functions are performed simultaneously, it is a challenge to confirm a machine.
Pharmaceutical equipment must operate in the same way every single time. Not three roads, but only one way to make products. The concern for personal computer systems is: whether it can be done, one way wrong, the computer will find another way to bypass it. For the blue screen of the desktop computer, many companies are afraid that this kind of accident will happen repeatedly.
Fourth, the reliability of the servo system
Some pharmaceutical packers insist on using a servo system operated by a PLC controller. In essence, they make the machine "stupid" so that it doesn't work properly. Although the computer is still there, it is isolated, only for the safety and data recording of the 21 CFR Part 11 regulations, the machine is operated by the PLC, which may improve the stability, but also lost a lot of the servo system The primary location benefits.
Of course, there are other ways to ensure stability. The key is to get control of the computer processor before the Windows system. On a computer-controlled wrapper line, the control structure acquires 100% control of the processor after initialization is complete and the Windows system takes control of the processor. Then it hands the processor time to the Windows system, at which point you can run the Windows program, but under the control structure. In this case, if the Windows system freezes, the packaging line will remain operational. You just have to switch to manual control because the display unit has failed, but your packaging line is still running.
For some vendors, this situation is still dangerous. They can use the combined control of the computer and PLC controller to switch the PLC by using the human-machine interface. Many systems use a servo control card inserted in the computer card slot. The computer software sends commands to the servo control card that controls the PLC. The servo system is dependent on the PLC that is executing the process, and then any feedback about the process is sent back through the PLC.
Other companies are attracted by hybrid systems. They like the simplified operation, data acquisition and repeatability brought by the servo system. Separating the PLC from the HMI also reduces the possibility of confirming the errors caused by the packaging process. Other vendors don't want to deal with the headaches of the PC system. They just want to know how to keep it running and they are worried about its stability. If you buy a PC that runs on the front of the machine, they first ask for the shelf life of the PC and be sure to buy the computer accessories.
Application status of servo control system in the field of pharmaceutical packaging
The servo system is an automatic control system that arbitrarily changes the output control amount of the object such as the position, orientation, and state of the object following the input target (or given value). One of its main components is the controller, which is the main factor affecting the performance of the servo system. Commonly used motion controllers include PLC, PC-Based motion control card, dedicated system and driver integrated motion control, and the motion control system changes the predetermined command into the desired mechanism motion through the servo drive.