Servo system realizes rapid and accurate production changes
whether it is dealing with biscuits, toothpaste, medicine or cosmetics, contract packers are always under pressure to quickly make changes in production mode to meet their customers' various cardboard packaging requirements. To meet this need, packaging division industries, Inc. (PDI), a contract packer in Northlake, Illinois, installed a servo driven vertical cardboard packaging machine from ultra packaging. Ultra packaging, an original equipment manufacturer based in bensenville, Illinois, has been providing services to the packaging industry for more than 13 years, and is familiar with the challenges its customers face in changing production patterns
Figure 1: the advantage of using the servo system is that the electronic cam line of the cardboard vertical shaft
can accurately control the product position and synchronize with the speed of the conveyor belt
the traditional vertical cardboard packaging machine relies on the mechanical power shaft and connecting rod to erect the cardboard box and move it on the machine. In the process of seeking to improve the effective running time of the machine, ultra packaging company analyzed the shortcomings of the mechanical cardboard packaging machine, including the time required for machine maintenance and troubleshooting, and more importantly, the time required to change the packaging machine with product changes. The company wants to simplify these tasks and reduce the work required to perform them
in its latest machine design, ultra packaging company adopted the full servo Gen III packaging automation scheme, and successfully converted the mechanical control motion on its vertical cardboard packaging machine into a servo motor and drive system from the electronic drive and control technology group of Bosch Rexroth company
in order to understand the vertical cardboard package, f=0.98 × 1250=1225n installed on the machine 10. Deformation measurement accuracy: the benefits brought by servo control movement within ± 0.5%. Let's take a look at the functions of Veronica cardboard packaging machine of ultra packaging company. The servo motor is used to control the key parts of the machine and provide precise synchronization of folding and bonding of cartons, products and cardboard hinges. The flat blank cardboard stands upright to form a cardboard box, which is then placed on the conveyor belt passing through the machine. In this process, the bottom of the carton is closed and the products are loaded through the opening on the top of the carton. Then the upper part of the carton is closed and glued. The whole process must be closely synchronized by the servo system to avoid frequent jamming of the carton by the machine
in this process, seven Bosch Rexroth ecodriver CS drivers and MSc small AC servo motors are used to provide machine synchronization, cam distribution and bonding functions. The servo driver is controlled by SERCOS digital optical fiber network, which is the industry standard, and provides 32-bit command signal and diagnostic analysis feedback for each AC servo system in the system
instead of using traditional programmable controllers for motion control, the machine is controlled by Bosch Rexroth's high-performance PPC (PowerPC) motion and motion controller. This compact rack system provides full synchronized movement in all axes, as well as logic programming for 24 volt DC i/o connections on the machine. The analog i/o is connected to two AC drives that operate the carton and discharge conveyor at an adjustable speed. Ultra packaging chose this control system because of its multi axial synchronization ability and its ability to resume production without reset after blocking or power failure
veronica's servo control makes our production line start-up time longer and shutdown time, troubleshooting and maintenance time shorter
for ultra packaging company, this servo system centered design of Veronica model is the first time, and this design is also unique in the industry. Veronica offers a continuous or intermittent cardboard packaging speed of 20 to 120 cartons per minute, and supports a wide range of carton sizes, from small to 2 × zero point seven five × 4.5 inches, up to 10 × four × 12 inches. Its main feature is the so-called fast and simple production mode switching ability
with the increasing demand for domestic composite polyurethane adhesives and the continuous innovation of utilization methods, Bob stockus, vice president of ultra packaging company, said, "for contract packers or other enterprises involved in packaging that need to frequently switch production modes, compared with the common time required for mechanical changes of 30 to 90 minutes, Veronica's typical switching time of 10 minutes is an attractive and cost-effective feature."
according to stockus, it takes only 3 seconds for a manufacturer to switch from a cereal food packaging box with a width of 7.5 inches (measured from left to right) to a toothpaste box with a width of 1.75 inches, while it takes 10 to 12 minutes to switch on a mechanical cardboard packaging machine. Similarly, the vertical (depth) scale change takes about 3 seconds, while the mechanical cardboard packaging machine takes 5 minutes
veronica operators can modify up to 50 carton size settings through the human-machine interface panel. Ultra packaging also adds a feature that enables each product to be displayed in the form of an image on the HMI screen, rather than in the form of a product code or number. This enables the operator to identify the product faster, making it easier and more convenient to make modifications
stockus said, "the combination of Rexroth servo system and PPC enables Veronica operators to simply click the icon on the HMI screen to modify the product size. This enables contract packer customers to significantly shorten the shutdown time and improve the product switching ability. And stronger ability means higher profits."
stockus said that the synchronization of motion control was the biggest challenge when designing Veronica. The first servo system used by ultra packaging company was provided by another supplier and configured into five independent servo drivers, so there are problems in achieving accuracy and synchronization. The company then evaluated a variety of technologies from other suppliers. They considered technology, price, applied knowledge in the food and packaging industry, and the level of technical support expected from suppliers. Stockus believes that the company chose Bosch Rexroth as the supplier to close the oil return valve because it valued the latter's experience in the packaging industry and its multi axial synchronization ability of servo system/ppc packaging technology. Another feature that affects ultra packaging's decision is that Rexroth's servo system does not need to be reset after blockage or power failure. The system will remember the position of the motor drive shaft, which increases the recovery speed of the machine by as much as 80%
the hinge folding function of servo control of paperboard packaging machine is an example of rapid recovery, which is a relatively unique function in the industry, because it is usually a mechanical operation. Stockus said, "the advantage of turning this movement into a servo control mode is that the program of the machine can be set to stop when the carton hinge fails to fold and causes blockage, so as to avoid damage. In addition, there is a warning light to send a blockage alarm to the operator. The touch screen of the HMI will display the position where the blockage occurred, and the machine will quickly reset to the appropriate position."
Figure 2: the servo driven Veronica vertical paperboard packaging machine of ultra packaging company is an ideal machine for end users and cooperative packers who need to quickly change the production mode during packaging operations.
Figure 3: Veronica uses Bosch Rexroth's PPC motion and logic controller to control,
commands its compact driver through SERCOS optical fiber network.
on the contrary, Jam on the mechanical hinge folding machine will damage the cardboard box (may damage a series), and it is necessary to use a wrench or other tools to readjust the product position of the machine. Rexroth's servo motor, driver and PPC work together to automatically reset the position, remember the original position and perform corrective actions, so the carton will not be lost. The time required to solve this type of blockage is also significantly reduced. On average, it takes less than 2 minutes for the servo system to solve a blocking problem, while it takes up to 10 minutes for the corresponding mechanical equipment to solve the same problem
another advantage of servo control is that the intermittent motion curve is automatically calculated, which can maintain an appropriate stay during loading at a variety of production speeds and corresponding product sizes. Similarly, the electronic cam line of the cardboard vertical shaft realizes accurate product positioning, which is synchronized with the speed of the conveyor belt, and the high-speed retraction of the vacuum mold unloading cup avoids interference with the moving machine parts
stockus believes that the highlight of the design of servo system and machine is:
■ use the preset configuration sheet to quickly switch, quickly identify the blockage, immediately solve the problem and resume production, significantly reducing the shutdown time
■ with torque setting, it sends a signal to shut down the machine in case of blockage, so as to avoid damaging the cardboard box and prevent the operator from being injured by hanging clothes in rare cases
■ the use of roller chains is eliminated and timing belts are used instead. Compared with the packaging machine using roller chains, the points requiring lubrication on the machine are reduced by 75%
PDI company is one of the first customers of ultra package company who intend to add Veronica vertical cardboard packaging machine to the production line. Rey interian, the maintenance manager of PDI, said that the company purchased the packaging machine to expand the production capacity of its 540000 square foot plant. PDI company mainly provides services for retail and warehousing enterprises that need to pack biscuits or other products in multiple units, so it is not surprising that interian defines the biggest challenges PDI company faces as fast switching production mode, fast start-up and overall diversified product processing capacity
for PDI company, the main advantage of servo drive is that it eliminates the manual adjustment of carton length and depth when switching production mode. Interian also listed other benefits of servo driven packaging machines, including production speed, production positioning accuracy, carton size diversity, and reduced maintenance workload. According to interian, "this kind of packaging machine has increased the productivity of PDI by 15%. Of course, the specific number is also related to the packaged products. The typical production mode switching time has been reduced from nearly 6 hours required by the equivalent mechanical packaging machine to 30 minutes of Veronica."
interian also pointed out that the rapid fault point identification function enables the operator to quickly solve the blocking problem or other problems, and restore the packaging machine to the production state. This process takes a fraction of the time required by the mechanical packaging machine. Interian also believes that the use of timing belts is a key factor because timing belts significantly reduce noise levels compared to roller chains running on guide rails. He said, "timing belts are safer for operators, because once an accident occurs, the injury consequences caused by metal roller chains and lugs are more serious than those caused by Veronica's timing belts."
interian said, "Keeping the packaging machine running is obviously crucial for businesses like ours, because we have to deal with a large number of different product sizes and configurations in a shorter operation period. Veronica's servo control enables us to maintain the production state for more time, while switching production mode, troubleshooting and maintenance requires less shutdown time. Naturally, this makes PDI company have a greater ability to deal with a variety of products ability