Lenze blow-fill-spin solution

1. Introduction

With the increasing expansion of the beverage consumption market, the demand for PET materials is bound to rise. In the face of increasingly serious environmental problems, how to save energy is also the primary problem of filling beverage equipment, traditional filling equipment, because the empty bottle is conveyed by the dial wheel between the blowing machine and the filling machine, this mode is easy to cause the extrusion and deformation between the bottles, therefore, at present, the blow-fill-screw-screwing machine can directly carry out the forming, filling and capping work of the bottle, so that the extrusion between the bottles can be avoided, and the lightweight bottle can meet the process requirements in this way, and each bottle can save about 4 grams. If a 36,000 bottle/hour blow-fill-spin machine works 10 hours a day, it can save about 526 tons of PET material per year. Therefore, the development of blow-fill-spin machine will be the main trend in the international market, at present, for most of the blow-fill-spin machine, the blow-filling machine part is mainly driven by frequency converter, and the filling and capping machine is driven by servo and follows the encoder of the blow-filling machine for synchronous operation. In addition to the proven solution for this model, Lenze has also developed a complete servo solution, in which the blow-moulder, filler, capper and heating system are all servo-driven. We have accumulated a lot of experience in the rapid braking, phase synchronization and logic control of the whole machine. The schematic diagram of its equipment is shown in the figure: Figure 1 Blowing, filling and rotating machine.

2. The composition of the blowing, filling and rotating machine

The blow-fill-screw-screw machine is mainly composed of a blow molding machine, a filling machine, a capping machine and a heating system. The bottle blowing machine is mainly responsible for the heated bottle blank, through the action of the stretching mechanism, so that the preform is stretched, and then blow air into the bottle, and finally the bottle finally forms a qualified bottle under the condition of pressure and temperature, which is taken out by the manipulator, and its process flow is: the preform is heated →→ the manipulator→ the turntable mold→ stretching pre-blowing→ blowing → exhausting → finished bottle→ transition dial → filling → capping → products. Filling machine: The filling machine is a kind of equipment that injects raw materials into the bottle, the filling machine has different filling heads according to the different output of the equipment, and its principle is to transfer the blown bottle to the filling machine by the transition dial. The bottle is clamped by a clamp on the lifting cylinder, which clamps the bottle mouth and is lifted and lowered by the cam. The filling machine adopts gravity filling method, the bottle mouth rises and opens the filling valve, starts filling, and the filling ends when the raw material rises to the position of blocking the air return hole. Capping machine: Capping machine is a kind of equipment that screws the cap on the bottle and seals the bottle. The bottle is fed into the capping machine by a transition dial. The anti-rotation knife on the capping machine jams the neck of the bottle, keeping the bottle upright and preventing rotation. The capping head rotates and rotates on the capping machine, and realizes the actions of capping, covering, capping, and capping under the action of the cam to complete the whole capping process. Heating system: The heating system is the key factor of the quality of bottle blowing, and the whole process is heated by multi-section infrared heating lamp, and the temperature is adjusted by PID by controller. The preforms are driven by a rotating chain and rotate through a heating lamp to obtain the optimum temperature for the preforms to be conveyed to the blow moulder system. See Figure 2 for details.

3. Lenze solution

There are three main application schemes for Lenze in the blow-fill-spinning machine, the first is a single-axis servo drive scheme, which is mainly for the blow molding machine to be driven by a frequency converter, the filling machine and the capping machine are driven by a servo motor together, and the servo runs synchronously with the single-turn absolute encoder of the blow molding machine. The second is the two-axis servo drive scheme, which is the same as the first one, except that the filling machine and capping machine are each driven by a servo motor. The third is a full servo solution, which will be analyzed in this article, with the first two using Lenze's drive-based system solution and the latter using Lenze's controller-based system solution. This solution is a centralized control solution, all motion control programs are completed by the motion controller, and each servo axis module is controlled via the EtherCAT bus.

3.1 Lenze's main products

(1) Panel controller p500: This series of products is an industrial computer product based on PC technology launched by Lenze, its software adopts Windows CE 6.0 operating system, built-in Codesys control software and VisiWinNET Compact CE interface monitoring software. Its controller function integrates logic control and motion control, and the programming mode conforms to IEC 61131-3 (IL, LD, FDB, ST, SFC and CFC Editor) and PLCopen Part 1 + 2 programming environment, and supports CNC Graphic DIN 66025 Editor (G-Code) programming, Cam curve programming and design. In terms of hardware, the controller is equipped with two Ethernet ports, two USB ports, one EtherCAT interface as standard, and supports an extended communication interface, which can be installed with Can and Profibus-DP communication.

(2) Servo driver i700: i700 is a simple servo product launched by Lenze for the controller, which adopts the hardware configuration of Lenze's highest-end servo. The servo drive does not have PLC and motion programming capabilities, and all programs, version information and motor parameters are performed by the motion controller.

(3) GKS series asynchronous servo geared motor: This product is composed of Lenze's MCA geared motor combined with G series geared motor, which has the advantages of high precision, impact resistance, and long life. This series adopts a straight shaft output method, and supports two mounting methods: solid shaft and hollow shaft. Asynchronous and synchronous servos can be used in different applications. Due to the large inertia and continuous operation of the filling equipment, the high inertia matching function of the asynchronous servo is very suitable for the operation of this equipment. At the same power, the asynchronous servo is also the best in terms of phase synchronization accuracy. This series of servos can meet the control accuracy requirements of the equipment (about 2mm) under both low-speed and high-speed operating conditions, and can also effectively avoid jitter problems at low speeds.

3.2 Lenze Solution

The system software adopts the common virtual axis working mode, and each real axis is synchronized with the virtual axis, which realizes the functions of phase synchronization, automatic return synchronization, zero finding and start and stop between the axes. The hardware host computer uses Lenze P500 products to connect with the Lenze servo controller I700 and IO system through the EtherCAT bus for motion control and logic control functions. The servo power supply adopts a centralized mode, which not only connects the servo modules through the DC bus for power supply, so as to simplify the wiring work, but also realize the energy sharing between the axes, so as to achieve the purpose of energy saving. The motor is composed of LenzeGKS asynchronous servo geared motor. For details, please refer to the topology diagram of the blowing, irrigation and rotation system in Figure 3.

3.3 Main Functions Implemented

Lenze combines customer process requirements and product characteristics to achieve the following functions:

(1) Imaginary axis control: using the imaginary axis as the main axis, each real axis can be completely synchronized with the imaginary axis, effectively avoiding the cumulative error caused by the cascade system;

(2) Power-off synchronous shutdown: Power-off synchronous shutdown function can be used for unexpected power-off of the production line. The real axes of different inertia can be stopped synchronously. Its main principle is to convert the inertial kinetic energy of the machine into servo electric energy, and then brake the motor. This function must require that the control loop of the servo has a constant parallel connection between the 24V control power supply and the DC power supply between the servo.

(3) Automatic return synchronization: The equipment requires that the phase synchronization between the slave shafts must be synchronized during the operation process to avoid the misalignment between the bottle clamps, thereby damaging the bottle clamps. Therefore, the servo automatically detects the position between the servos before the machine is operated. If it is not in the synchronization position, the servo will return to the synchronization position according to the shortest bottle clamping distance during start-up, and then run synchronously. Of course, by observing the synchronization status indicator of the monitoring system, if it is not in the synchronization position, it can also return to the step position with one key.

(4) Zero point setting: The zero point setting of the equipment adopts the manual setting zero point method. Since the zero point switch is not installed, the zero point of the equipment needs to be set one by one by the operator through human eye observation. The servo itself has the function of automatic saving of zero point, so after the zero point setting is completed, as long as the servo motor is not manually disassembled or the servo is powered off, the manual turning servo can automatically remember the zero point.

(5) Real-time error detection: synchronization accuracy is an important indicator for the normal operation of equipment. Each servo program is equipped with a real-time error monitoring program, which can be compared with the position of the servo encoder and the position of the imaginary axis in the servo controller. The comparison command is carried out every millisecond, so that if the position error of the business trip is found every millisecond during the operation of the equipment, the equipment can immediately enter the parking procedure.

3.4 Lenze Highlights

After many years of investment and technical experience in the filling industry, Lenze now has a number of mature technical highlights. The main technical highlights are as follows:

(1) Servo technology is introduced, and the electronic axis synchronization mode is used to replace the traditional mechanical axis synchronization mode. The introduction of servo technology realizes the independent operation of each unit of the equipment, which facilitates the commissioning, troubleshooting, machine cleaning, daily maintenance and other operations of the equipment, breaks through the restriction of the speed of the mechanical axis synchronization mode, and makes the equipment installation more compact and flexible.

(2) Power-off synchronous parking function and phase holding. The servo has a mechanical energy feedback function, which can be shared with the control of the intelligent servo and the centralized power supply module, and realize synchronous shutdown in the case of power failure. The servo itself has the function of position saving, and the phase holding function can be realized with the brake.

(3) Zero point hold and automatic return to the synchronization position. The servo has the function of holding the zero point, after automatic zeroing, if there is no mechanical change, there is no need to find zero, the equipment can automatically return to the synchronization position according to the shortest distance in a bottle position, so as to reduce the starting time. At the same time, the system automatically collects the zero point signal every week, which is used to verify the mechanical wear and slip error, if the set error is reached, the operation is stopped immediately, and the machine can automatically re-find the zero point when starting, and then run again.

(4) The common imaginary axis working mode is adopted to avoid the accumulation of errors. The servo adopts a 32-bit operating system and adopts a remainder compensation mechanism to avoid the generation of calculation errors.

(5) Lenze integrated reducer to avoid mechanical errors. Lenze uses a one-stage pinion to directly drive the gearbox gear, and the pinion interference fit is used to connect, so it has excellent performance such as high precision and low noise.

4. Prospects

The aseptic cold filling process is appreciated for its ability to protect the nutritional integrity of the beverage and ensure the original taste of the beverage. At present, the aseptic cold filling production line is still in its infancy in China, and facing the huge development potential of the consumer market in the future, the aseptic cold filling production line will surely develop in the direction of high speed and safety.

The high speed of the production line means that it can lead to greater production capacity with the same production level and workshop input. At present, the average production speed of domestic aseptic production line is 42,000 bottles/hour, which has reached the international advanced level. Due to its mechanical wear and precision, the speed of the traditional mechanical coupling production line can no longer meet the process requirements. Therefore, the use of a split servo drive system is an important factor in the realization of high-speed production lines at present. With the ever-changing process requirements, the aseptic cold filling line will further develop in the direction of more separation and more servo system investment in the future, so as to further increase the production speed.

A safe production line is a prerequisite for people to drink healthy beverages. Since there is no high-temperature sterilization link, this requires that the aseptic cold filling production line must achieve a sterile environment from the perspective of mechanical design, such as the filling clean room must meet the air purification requirements of more than 100 levels, and the filling valve structure must also be simple, easy to clean, and ensure that there are no sanitary dead ends such as pinch seams in the valve. The aseptic cold filling production line must focus on optimizing the mechanical structure and production process methods, and develop in the direction of sterility and safety.

In short, in the future beverage industry, the aseptic cold filling production line will lead the technical trend of the filling production line with its various advantages, and become an important beverage production method.

Lenze blow-fill-spin solution

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