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TPU, TPR sole machine principle

1. The working principle of the automatic disc type plastic injection molding machine
As we all know, there are a large number of successful cases of frequency conversion and energy-saving transformation of horizontal injection molding machines in China. The fully automatic disc-type plastic injection molding machine in shoe-making enterprises is the main common electrical equipment in shoe-making enterprises, known as electric tiger. my country is a big shoe-making country with a large number of shoe-making equipment, but there are relatively few units involved in energy-saving transformation. The main reason is that people are not familiar with the working principle of automatic disc-type plastic injection molding machines.
1.1 Mechanical characteristics of fully automatic disc-type plastic injection molding machine (hereinafter referred to as: disc machine)
1) This machine is specially used to produce all kinds of high-grade single-color, double-color and three-color sports shoes, leisure shoes soles, boys and girls soles and other products.
2) Raw materials are suitable for the production of foaming and other thermoplastic raw materials, such as PVC, TPR, etc.
3) The machine is controlled by computer programs (single chip microcomputer, PLC), the main and auxiliary machines are precisely controlled, easy to operate and easy to maintain.
1.2 Comparison between disc machine and traditional horizontal injection molding machine
1) Hydraulic motor
The oil pumps of horizontal injection molding machines and disc machines are quantitative pumps. During the injection molding process, the pressure of the oil pump changes frequently. The traditional treatment method for the low pressure maintenance process is to release the pressure through a proportional valve, and the motor has been running at full speed under power frequency. The waste of electric energy is very serious.
2) According to the model of the disc machine, it is divided into single-color machine, two-color machine, three-color machine and other models.
Among them, the monochrome machine has only one host, which is similar to the horizontal injection molding machine.
The two-color machine consists of a main machine and an auxiliary machine. The auxiliary machine is responsible for injection, melting, upper mold, lower mold and other actions. The main machine includes the actions of the auxiliary machine, and there is an additional disc rotation action to realize the movement and positioning of the mold.
The three-color machine consists of a main machine and two auxiliary machines.
3)Number of molds
4)Horizontal injection molding machines generally only have one set of molds working, and when the production process is changed, the molds need to be replaced.
The number of molds of the disc machine is different according to the model. Generally, there are 18, 20, 24, and 30 sets of molds. According to the production process, through the control panel, set whether the mold position is valid or not. For example: TY-322 model, 24 station mold positions (24 molds can be installed), all or part of the molds can be flexibly selected as the effective mold positions according to the needs during production). When the disc machine is working, the large turntable performs high-speed clockwise rotation, and the PLC or single-chip microcomputer executes the calculation of the program. When only valid mold positions are detected, when the PLC or single-chip microcomputer scans for a deceleration signal, the turntable starts to decelerate. When the positioning signal is reached, the turntable performs precise positioning. Otherwise, if no valid mold position is detected, the large turntable will rotate to the next valid mold position.
As long as the horizontal injection molding machine has a mold clamping or mold opening signal, it will perform related actions.
4) Pressure adjustment method
The pressure adjustment methods of horizontal injection molding machines and disc machines are all pressure proportional control methods, but the injection pressure of each mold of the disc machine (more molds) can be independently set through the control panel, which is suitable for the manufacture of products with different injection volumes .
The horizontal injection molding machine produces each product, and the relevant parameters are consistent.
5) Mold working method
When the horizontal injection molding machine is working, the fixed mold does not move, and only the movable mold executes left and right mold locking or mold opening when there is an instruction, and moves in a straight line from left to right.
When the disc machine is working, the fixed mold and the movable mold are moved and positioned by the large turntable. When there are mold clamping and mold opening instructions, the oil cylinder performs the rising or falling action. When taking the product, the operator manually opens the movable mold to take out the product.
6) Disc (turntable)
The fully automatic disc type plastic injection molding machine gets its name because the turntable is round, referred to as disc machine (sole machine). Several equal portions were divided on the disk. Such as TY-322 is divided into 24 modules.
If neither the main machine nor the auxiliary machine detects an effective mold position, and both the main machine and the auxiliary machine are in the mold opening state, the PLC or the single-chip microcomputer sends an instruction, and the disc is provided with pressure by the main machine to rotate at a high speed. The system automatically detects the effective mold position, and the disc is precisely positioned after deceleration.
7) Cooling method
The traditional horizontal injection molding machine has the concept of “cooling time”. A cooling water cycle is installed on the mold to protect the cooling of the mold and the product.
The disc machine is different. It does not have a cooling water circulation system, because after the product is formed, the turntable of the disc machine itself is in a rotating state or in a standby state for a period of time. In addition, there are several cooling fans installed on the machine to cool the mold and the product. .
1.3 Working principle of disc machine
In the injection molding process of the disc machine, various actions such as clamping, injection, melting, mold opening, and disc speed and speed have different requirements for speed and pressure. They are set by the proportional value on the control panel. For example: P1 sets the closing mold pressure, P2 sets the injection primary pressure, P3 sets the injection secondary pressure, and P4 sets the feed pressure. When the flow pressure demand of the disc machine changes, the load pressure and flow are adjusted by the proportional valve (overflow valve) at the outlet of the oil pump, and the excess oil is overflowed back to the oil tank under high pressure.
The single-color disc machine has only one main engine, which mainly provides pressure to the system to complete the action of injection and melting, as well as the action of clamping and opening the mold. In addition, it controls a turntable system to complete the movement and positioning of the mold.
The two-color machine can be divided into main machine and auxiliary machine. They are mainly composed of heating, glue injection, melt glue system, and mold locking system. The three-color machine is similar to the two-color machine. It consists of a main machine and two auxiliary machines. The host is responsible for the rotation and positioning of the disc.
The disc machine is divided into two parts: manual operation and automatic operation.
When operating manually, the operator must provide corresponding commands, and the disc machine will complete the corresponding actions. Such as glue injection, melt glue, upper mold, lower mold, disc rotation and other actions.
During automatic operation, after the selection of each mold position is completed, the feeding amount, pressure and time are set, and the temperature of the material tube has been heated, start the oil pump of the main machine, switch the manual and automatic unlocking to the automatic position, and press the automatic start button once. An automatic step can be performed.
1) If the current mold position is in use, after pressing the automatic start button, the feeding amount will be the set amount of this mold. If the feed does not reach the set amount, there will be an action of clamping the mold. Only the fast mold clamping action is allowed, and the slow mold clamping action is only available after the feed reaches the set amount. After the mold locking stops, the injection and mold opening actions are performed.
2) If the current mold position is not in use, press the automatic start button, the disc will move to the next used mold position, and the feeding amount reaches the set amount of the next used mold position. Material action, after the turntable is positioned, fast mold clamping (set by time), the timing stops, and when the feeding time arrives, slow mold clamping is performed, and the injection and mold opening actions are performed after the mold clamping stops.
3) When the main machine and the auxiliary machine are used at the same time, it is necessary to wait until the automatic actions of the main machine and the auxiliary machine are completed and the mold is opened before the disc runs and rotates to the next mold position.
4) When the turntable stops moving before the “slow point” of the disc, the disc will slow down to the positioning stop when the “slow point” is detected. If the mold position is used, after positioning, the mold action will do the mold locking and other actions until the mold is opened. The turntable does not move, but the feeding action will execute the feeding of the next mold used. When the turntable is suspended (rotating clockwise), the turntable will move to the next mold position. If this mold position is not in use, the disc will be positioned at the nearest mold, and will not move to the next mold until the turntable pause is released.
5) In the automatic operation, switch the automatic state back to the manual state, except that the disc will perform slow positioning (the disc is switched during operation) and other actions will stop in time. It can be reset manually.
1.4 The power consumption of the disc machine is mainly manifested in the following parts
1) Electric energy consumption of hydraulic system oil pump
2) Heater power consumption
3) Cooling fan.
For shoe-making enterprises, power consumption is the main part of their production costs. Among the above-mentioned power consumption, the power consumption of the hydraulic oil pump accounts for about 80% of the power consumption of the entire disc machine, so reducing its power consumption is the key to reduce the power consumption of the disc machine. The key to machine energy saving.
2. The power saving principle of the disc machine
After understanding the working principle of the disc machine, it is not difficult to know that there is a very violent mutation process inside the disc machine, which has a great impact on the machine and affects the life of the entire injection molding system. At present, there are a large number of old equipment in domestic shoe-making enterprises, with low degree of automation and high energy consumption. The machine is generally designed according to the maximum production capacity. In fact, it often does not use such a large power during production. The speed of the oil pump motor remains unchanged, so the output power is almost unchanged, and there are large horses and small carts in production. Therefore, a large amount of energy is wasted.
Due to the unique characteristics of the main and auxiliary machines and the rotary mold of the disc machine, there are not so many effective mold positions used in production, such as: TY-322 model, 24 sets of molds, sometimes only a dozen sets are used , Even fewer molds are used in test machines and proofing, which determines that the main and auxiliary machines are often in a long-term standby state. The auxiliary machine only executes the action when it detects a valid mold position. When the disc rotates, the auxiliary machine does not do any action, but usually, the motor still works at the rated speed. At this time, the high-pressure overflow part not only does not do any useful work, but also generates heat, which causes the hydraulic oil to heat up. Yes, but also harmful.
We adopt the speed sensorless vector frequency conversion operation technology of the disc machine (refer to the electrical schematic diagram). The frequency converter detects the pressure and flow signals from the computer board of the disc machine in real time. The pressure or flow signal of the disc machine is 0-1A , after internal processing, output different frequencies and adjust the motor speed, that is: the output power is automatically tracked and controlled synchronously with the pressure and flow, which is equivalent to changing the quantitative pump into an energy-saving variable pump. The original hydraulic system and the operation of the whole machine require Power matching eliminates the loss of high pressure overflow energy of the original system. It can greatly reduce the vibration of mold closing and mold opening, stabilize the production process, improve product quality, reduce mechanical failures, prolong the service life of the machine, and save a lot of electric energy.

Post time: Mar-01-2023