Blow molding machine refers to the machine for producing bottles. The most obvious explanation is that it is a machine that can blow plastic particles (softened into liquid) or finished bottle embryos into bottles through certain process means. Blow molding machine is convenient and fast, with a large molding volume. After its appearance, it replaced most manual bottle blowing and was adopted by most beverage companies.

Introduction

Blow molding machine is a device that makes plastic particles into hollow containers through blow molding. The more common machines include hollow extrusion blow molding machines that use PP and PE for one-time molding, injection stretch blow molding machines that use PET, PC or PP for two-time molding, and newly developed multi-layer hollow extrusion blow molding and stretch blow molding.

Most blow molding machines are still two-step blow molding machines, that is, the plastic raw materials must be made into bottle embryos first, and then blow molding. Nowadays, environmentally friendly plastics made of PET are generally used. Blow molding machine: After the liquid plastic is sprayed out, the wind blown out by the machine is used to blow the plastic body to a certain shape of the mold cavity to make a product. This machine is called a blow molding machine. It is also a kind of bottle blowing machine, namely hydraulic bottle blowing machine.

The tubular plastic parison obtained by extrusion or injection molding of thermoplastic resin is placed in a split mold while hot (or heated to a softened state). After the mold is closed, compressed air is immediately introduced into the parison to make the plastic parison inflate and cling to the inner wall of the mold. After cooling and demolding, various hollow products are obtained.

Features

Plastic hollow containers are widely used in beverage, medicine, cosmetics, food and chemical industries due to their light weight, low price and high safety. They have attracted more manufacturers to choose plastic containers instead of traditional glass containers. The most advanced equipment, molds and raw materials in the plastics industry are all displayed one by one. New technologies and new applications emerge in an endless stream. Looking at the field of plastic hollow molding, it is also fruitful. With the soaring global oil prices, the price of plastic raw materials is also high. The development of alternative products with low energy consumption and low raw materials is also one of the market trends.

The oil-free airbag clamping technology has a large clamping force, and the toggle is less stressed and has a long service life. ¡¤The patented fly-out seal technology makes sealing, especially the sealing of wide-mouth bottles, easier.

Process History

Enoch Ferngren and William Kopitke first verified the blow molding process. The principle of this process originated from glass blowing. In 1938, Ferngren and Kopitke built a bottle blowing machine and sold it to Hartford Empire Company. This was the beginning of commercial blow molding. In the 1840s, the variety and quantity of plastic products were very limited, so the blow molding process did not develop rapidly until much later. With the increase in product variety and the improvement in productivity, more and more plastic products were soon made by blow molding. In the soft drink industry in the United States, the number of plastic containers has increased from zero in 1977 to 10 billion in 1999.

During World War II, the blow molding process began to be used to produce low-density polyethylene bottles. In the late 1950s, with the birth of high-density polyethylene and the development of blow molding machines, blow molding technology has been widely used. The volume of hollow containers can reach thousands of liters, and some production has been computer-controlled. Plastics suitable for blow molding include polyethylene, polyvinyl chloride, polypropylene, polyester, etc., and the resulting hollow containers are widely used as industrial packaging containers.

According to the method of making the parison, blow molding can be divided into extrusion blow molding and injection blow molding, and the newly developed ones are multi-layer blow molding and stretch blow molding.

The extrusion process is to extrude the plasticized plastic into the extrusion blow die through a screw, and then cooperate with the mold below and compressed gas to achieve the molding of the product.

The extrusion blow molding process consists of 5 steps:

1. Make the plasticized raw materials into plastic preforms;

2. Cut off part of the preforms and cut off the preforms by closing the mold;

3. Fill the mold cavity with gas to shape the preforms and cool them;

4. Open the mold and take out the molded container;

5. Trim the flash to get the finished product.

Process

1. Preheating

Irradiate the preform (embryo) with an infrared high-temperature lamp to heat and soften the body of the preform (embryo). In order to maintain the shape of the bottle mouth, the preform (embryo) mouth does not need to be heated, so a certain cooling device is required to cool it.

2. Blow molding

This stage is to place the preheated preform (embryo) into the blow mold that has been prepared, inflate it with high pressure, and blow the preform (embryo) into the required bottle.

The bottle blowing machines on the market are generally divided into fully automatic and semi-automatic.

The fully automatic bottle blowing machine combines the two operations of bottle blowing through the operation of the manipulator, eliminating the process of manually putting the preheated bottle blank (embryo) into the blow mold. It greatly speeds up the production rate, and of course the price is higher than that of the semi-automatic one.

Product Selection

How to choose the bottle blowing machine model you need is probably the most concerned topic.

Generally speaking, choose the model of the bottle blowing machine according to the product you need. For manufacturers with different usage, they generally focus on the number of cavities, the size of the bottle capacity, and the output per hour.

It is very important to choose the model that meets your needs according to your needs.

The left picture below: semi-automatic bottle blowing machine; the right picture below: fully automatic bottle blowing machine.

Operation steps

Step 1. Place the bottle blank in the bottle blank container and automatically enter the bottle blank positioning device through the conveying device.

Step 2. The preform with the mouth facing upward is automatically loaded onto the preform holder and then sent to the drying tunnel.

Step 3. After heating, the preform is sent to the blowing platform, then clamped, and then blown and stretched at low pressure, blown and stretched at high pressure, exhausted, and finally opened.

Step 4. The finished bottle is taken down from the blowing platform by the automatic demoulding system.

Technological Development

Beverage companies have two urgent needs for blowing equipment. One is that due to the continuous rise in the price of plastic raw materials, beverage companies are always thinking about how to reduce packaging costs to maximize profits, so they need to use advanced blowing equipment to produce lighter bottles; the second is that due to the rapid changes in the market, beverage manufacturers must respond flexibly to the increasingly shorter life cycle of beverages. Corresponding to this is the increasingly frequent product update problem in PET bottle production. In the production process, the time for changing molds needs to be minimized. These two urgent needs have posed a big problem for blowing equipment suppliers.

Closed Loop technology refers to integrating the process parameters of the online verification into the process control system of the stretch blow molding machine to form a closed production cycle process that combines automatic control and automatic adjustment. Intelligent machine control technology is designed to improve the quality assurance system of the blow molding machine. Through the use of the AgrPETWallplus monitoring system, various data of the bottle blanks such as bottle wall thickness can be monitored. During operation, data that deviates from the system rated value will be immediately identified, and this information will be promptly transmitted to the control system of the bottle blank heating unit of the blow molding machine. The control system will quickly reflect and individually control the rated value of each heating lamp in the heating furnace. Therefore, even if the data of each bottle is different, the quality of the produced bottles will remain stable and reliable if the initially set process parameters remain unchanged.

Maintenance

1. No material is added to the feeding position: Several situations need to be checked:

Is there no material in the hopper? If yes, you need to add material quickly

No: Please check whether the control contactor of the elevator is in the energized state. If it is in the energized state, quickly check whether the motor is in the energized and loaded state, because this situation is likely to be caused by the bottle blank (embryo) stuck in the lifting belt. At this time, the simplest method is to help lift manually.

If the control contactor of the elevator is not in the energized state, please check whether the bottle blank detection electric eye is not in the same straight line with the reflector.

2. The feeder is stuck in the feed tray: This situation is a headache. From experience, if the length of the bottle blank (embryo) is long and the weight is heavy, then this phenomenon is relatively rare.

3. The bottle cannot be taken out of the mold after it is blown.

First, the mold should be opened and opened and closed manually. If it is normal, run it in the empty running state. If it is also normal.

Please check your exhaust time setting. If the exhaust setting is normal and the problem occurs every time you blow a bottle, then it can be judged that the exhaust valve has a problem. Please open the exhaust valve to check its spring and seal (another phenomenon of this failure is that the exhaust sound is relatively loud or there is a sound of incomplete exhaust).

If you encounter a situation where many molds are in normal production but occasionally cannot open the mold, please check whether there are broken screws in the clamping pin. In addition, please check whether the clamping force is too large. If it is too large, it should be readjusted according to the standard.

4. The bottle is always pinched

Is the position of the robot misaligned?

5. The two robots collide

In this case, the robot needs to be manually reset, which is caused by misalignment.

Operation specification

Required knowledge of safety operation specification of fully automatic bottle blowing machine

(1) Before starting each shift, all moving parts must be lubricated once. (Robot, robot rail, mold opening and closing rail)

(2) The swing arm can be lubricated once every (3-4) days. The large and small chains of the heating machine can be lubricated once a month. Regularly check whether the reducer of the main engine and the reducer of the heating machine are short of oil. The main engine bearing can be lubricated once every 3 months.

(3) Before production, check whether all moving parts are firm, whether the screws are loose and fall off, especially in places with strong impact force, and whether the belt transmission part is abnormal.

(4) Check whether the high-pressure air source, low-pressure air source, power supply, and water source are normal.

(5) Check whether the emergency stop switches, safety door switches, and protection device detection switches are normal.

(6) Check whether the heating head is feeding the embryo and the embryo drop part is working normally. If the embryo is not inserted in place, the nut of the embryo pressing device can be adjusted.

(7) Check whether the lamp is damaged or broken. Replace it in time.

(8) Check whether the pneumatic components are leaking and whether the movements are sensitive.

(9) Check whether the triplet has abnormal leakage, whether it is blocked, and whether the water storage capacity of the water cup is too full.

(10) When the solenoid valve of the fully automatic bottle blowing machine encounters an abnormality, it must be cleaned in time (clean once every 3.5 million bottles blown).

Operation principle

Blowing machines are mainly divided into three categories: extrusion blow molding machines, injection blow molding machines and special structure blow molding machines. The processing technology is mainly divided into one-step and two-step methods. The one-step and two-step blow molding machine molding processes are mainly used for PET and BOPP hollow container molding. Both have their own characteristics and are widely used. In comparison, the two-step method is more suitable for centralized production of bottle blanks and decentralized blow molding of bottles; while the one-step equipment is more suitable for online production of beverage companies.

The blowing procedure of the bottle blowing machine mainly consists of 6 steps:

1) First, put the heated plastic embryo into the mold;

2) Use the mold locking cylinder to lock the mold;

3) Then use high pressure or mechanical structure to lock the embryo mold;

4) Pre-blowing with medium and high pressure, and at the same time, stretch the cylinder to expand the embryo mold;

5) High-pressure blowing, the bottle embryo is shaped according to the mold, and the pressure is maintained for a certain period of time;

6) Release the high pressure in the formed bottle, reset the cylinder and take the bottle.

Pneumatic equipment is used in many places during the operation of the bottle blowing machine; from discharging - locking - stretching - high-pressure blowing\deflation - taking the bottle, this series of actions are all assisted by pneumatic equipment. For example, in the stretching high-pressure blowing and deflation circuit, the air circuit is divided into two parts, the normal pressure part and the high pressure part.

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