Background and significance of the research
A blow Molding Machine is a kind of hollow blow molding equipment. It appeared in the 1930s, and its manufacturing process originated from the blowing of glass products, with engineers Enoch Ferngren and William Kopitke developing the first commercial blow molding machines. So far, the blow molding machine has made great progress in the blow molding process and molding machinery. The blow molding technology is widely used in polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), polyethylene terephthalate Blowing plastic bottles such as glycol ester (PET) and polycarbonate (PC) . Polyethylene Terephthalate (PET) was first developed by British scientists J. tt. Winnfield and JT Dickon in the early 1940s, and then Dupont developed the first PET in the 1970s. A PET bottle . PET has been widely used in beverage bottles and edible oil bottles because of its good transparency, airtightness and toughness, as well as its low price and non-toxicity [3, 4]. The total output of PET bottles in the world has grown rapidly, and the demand for PET bottles in my country has also increased year by year . However, since domestic PET bottle blowing machines are inferior to foreign equipment in terms of production technology and performance indicators, most domestic PET bottle blowing machines use imported equipment. The intelligent blow molding machine is of great significance. At present, the world’s leading bottle blowing technology manufacturers include Italy’s SIPA, France’s SIDEL, Germany’s KRONES, and Japan’s Aokiku Research Institute. The domestic leading bottle blowing machine manufacturers include Guangzhou Tech-Long, which produces rotary blow molding machines. And the production of the linear blow molding machine, such as the crown, Jiahong and so on. With higher requirements for the automation and intelligence of the blow molding machine, the traditional sequential control system can no longer meet the needs of the multi-axis linkage of the blow molding machine. An increasing number of blow molding machine systems use an all-electric servo control system. The servo motion controller has high-speed communication and various motion control methods, which can realize electronic gear, electronic cam, interpolation and multi-axis linkage control, which can further improve the efficiency and quality of the blow molding machine.
Research status of bottle blowing machine
A PET bottle is a hollow plastic product that is formed by hollow blow molding. Hollow blow molding is a process in which the hot-melt plastic in the closed mold is inflated with compressed air and then shaped into a hollow plastic product after cooling. The main methods of hollow blow molding can be divided into two categories: extrusion blow molding and injection blow molding . In addition, on the basis of extrusion blow molding and injection blow molding, extrusion-stretch-blow molding method and injection-stretch-blow molding method have been developed, which can be specially classified as stretch blow molding Law. Equipment using extrusion blow molding, injection blow molding and stretch blow molding methods are called extrusion blow molding machine, injection blow molding machine, extrusion stretch blow molding machine and injection stretch blow molding machine, respectively [ 7, 8]. Hollow blow molding South China University of Technology Master’s Thesis 2 Classification of molding machines is shown in Figure 1-1.
|PET hollow blow molding machine||Extrusion Blow Molding Machine||Single and multi-die extrusion blow molding machine|
|Multilayer co-extrusion blow molding machine|
|Injection blow blow molding machine||Single and Multi-Mold Injection Blow Molding Machine|
|Multilayer Injection Blow Molding Blow Molding Machine|
|Stretch blow molding machine||Extrusion Stretch Blow Molding Machine|
|Injection stretch blow blow molding machine|
Figure 1-1 Classification of hollow blow molding machines
Hollow blow molding machine
Extrusion Blow Molding Machine
The main production process of extrusion blow molding is to extrude the tubular parison from the head through the continuous rotation of the extrusion screw, so that the parison is placed between the open molds. When the extruded parison reaches the specified length, The mold is closed and the parison is cut at the same time. At this time, compressed air is injected into the cut parison. The pressure of the air makes the parison inflate into the shape of the mold cavity, and the product is cooled and formed. Finally, the mold is opened and the finished product is released from the mold. [9, 10].
According to the extrusion blow molding process, the extrusion blow molding machine generally includes an extrusion device, a die, a parison cutter, a mold, a clamping device, a clamping device, an air blowing unit, an electric control unit, etc. . Extrusion blow molding machine According to different molding methods in the molding process, extrusion blow molding machines of different models and different scopes of use are formed; according to different parison materials, it can be divided into single-layer extrusion blow molding machine and multi-layer co-extrusion blow molding machine.
The main advantages of extrusion blow molding are :
(1) The molding pressure is relatively low (0.2~1.0MPa), and the residual stress of the product is small, so it has better mechanical properties;
(2) Extrusion blow molding can be applied to products with complex shapes, integral structures and strong structures;
(3) Through multi-layer co-extrusion, the impermeability of the product is improved, and it can be applied to plastic bottles such as pesticide bottles and chemical reagent containers;
(4) Extrusion blow molding has the advantages of low equipment cost, flexible product renewal and is suitable for various molding products.
However, extrusion blow molding products generally have low precision, resulting in flash waste, resulting in waste of raw materials, and extrusion blow molding equipment is relatively complex. At present, the major foreign manufacturers of extrusion blow molding equipment include Germany’s Kautex, Italy’s Plastic, Techne Graham and Uniloy Milacron and other extrusion blow molding equipment manufacturers. Domestically, there are Qinchuan Future Plastics, Zhangjiagang Huafeng Heavy Machinery, etc. There is also Jih Huang Company in Taiwan .
Kautex’s long-stroke extrusion blow molding machine KLS series, its production capacity can reach 7000~8000BPH (bottle per hour), the molding dies clamping force can reach 200~550kN, and the mold shifting stroke can reach 670~1480mm, which can be divided into orders Station and double station, each station can have 6~14 cavities .
The all-electric and semi-hydraulic driven PB series extrusion blow molding machines launched by Plastic can be divided into the single station and double station, of which the PB30 series can produce plastic bottles with a maximum capacity of 30L, and the PB5 series is equipped with a Ф50mm extrusion blow molding machine. Machine and three-layer co-extrusion head, when used to produce PE-HD and PP plastic bottles, the output can reach 2300BPH.
Techne Graham’s Advance line of extrusion blow molding machines feature an all-electric extrusion and blow molding unit that enables faster molding cycles and more energy savings than hydraulically driven equipment. Among them, ADV2-510/700 can blow plastic bottles with a capacity of 60mL~1L. The equipment can be equipped with up to four sets of molds and two systems. At the same time, the control system is used to control the clamping force, and the maximum clamping force can reach 180kN [16 ].
Uniloy Milacron’s UMS range produces 7-layer co-extruded plastic bottles up to 30L, with mold clamping forces ranging from 40kN to 500kN, with single-, dual-station and long-stroke screw options. The closure is designed with quick switching and T.C.S technology to control the strength and weight of the parison. UMS. EZ series is an all-electric extrusion blow molding machine, which adopts new energy-saving technology, which can effectively reduce energy consumption by 70% and lower maintenance costs .
The domestic manufacturer Qinchuan Future Plastics Machinery Co., Ltd. SCJC500×6 co-extrusion blow molding machine can blow up to 500L of six-layer plastic fuel tanks with high barrier properties and complex shapes. Zhangjiagang Huafeng Heavy Machinery Co., Ltd. HX series extrusion blow molding machine has a production capacity of 3600~8000BPH, and FT series production capacity can reach 1500~1400BPH.
The main production process of injection blow molding is divided into three steps. The first step is to inject the raw materials from the injection molding machine by the injection molding method, and the injection mold composed of a male mold and a female mold is injected into the injection mold; the second step is to adjust the temperature and reheat. ; The third step is to release the parison from the injection mold, and put it into the blow mold through a mechanical transmission device. After the mold is closed, the compressed air of 0.2~1.0MPa is introduced into the channel in the mandrel for blow molding, and finally, the product is obtained after demolding. . Since the process of injection blow molding hollow molding is roughly divided into two stages (injection parison and blow molding), the injection blow molding machine actually performs appropriate grouping of the injection device and the blow molding device according to different production conditions. South China University of Technology master’s thesis 4 sets, which can be divided into combination form and complete set form. The combined form is based on the original injection molding machine, adding a blow molding device and adding an appropriate control unit to form an injection blow molding machine. A complete set is an integrated machine consisting of an injection molding system, an injection mold, a blow molding system and a blow mold assembly. Injection blow molding machine can be divided into angle type and horizontal injection blow molding machine according to the structure of injection device and clamping device; according to the conveying method of injection parison, it can be divided into plane mobile type and rotary injection blow molding machine For rotary injection blow molding machines, according to the way the rotary table is installed, it can be divided into horizontal rotary and vertical rotary .
Injection blow molding is generally used to produce small-capacity plastic bottles and is not suitable for the production of plastic products requiring high barrier properties. However, injection blow molding has the advantages of high molding precision, no flash waste, higher energy efficiency than extrusion blow molding, better surface quality, and higher-finish, and is especially suitable for the manufacture of packaging products such as medicine and cosmetics .
Foreign manufacturers of injection blow molding equipment include General Machinery Company of the United States, Jomar Company and Uniloy Milacron Company of Germany, etc., and domestic manufacturers include Jiangsu Vinda Plastics Company and Liuzhou Jingye Plastics Company.
The injection blow molding machine IB-506-3V produced by General Machinery Company of the United States is a three-station hydraulic power transmission equipment, Allen Bradley programmable control, with automatic lubrication system and automatic diagnosis system. The molding cycle is generally within 10~15s. The weight is 125kg, the injection clamping force is 500kN, and the blow molding clamping force is 66kN .
Jomar is a manufacturer specializing in the production of injection blow moulding machines with a small footprint, energy savings and low maintenance costs. The model M-40 injection blow molding machine has an injection volume of 90kg, screw diameter of 35mm, an injection clamping force of 345.5kN, and a blow molding clamping force of 38.1kN. It can produce plastic containers with a maximum diameter of 122mm and a length of 203mm. Model M-135 molding machine, one injection volume is 450kg, screw diameter is 76.2mm, injection clamping force is 1227kN, blow molding clamping force is 255kN, and it can produce plastic containers with a maximum diameter of 147mm and a length of 254mm .
Jiangsu Vida Machinery Co., Ltd., a domestic manufacturer of injection blow molding machines, launched the MSZ60 series of injection blow molding machines. It is a three-station molding machine with a hydraulically driven horizontal injection unit, with a maximum injection volume of 280kg and injection clamping. The force is 600kN, and the blow molding clamping force is 89kN. The large aspect ratio is suitable for a wide range of raw materials. The bridge-type clamping structure, variable pump control system and large-capacity mold are suitable for various products. The cyclone series injection blowing machine WB07-5 manufactured by Liuzhou Jingye Company has a maximum injection volume of 175kg, an injection clamping force of 150kN and a blow molding clamping force of 30kN. It adopts a vertical molding process, integral cavity and composite Core technology, while variable pump technology reduces energy consumption by 30%.
According to the process of parison molding, stretch blow molding can be divided into extrusion stretch blow molding (extrusion stretch blow molding) and injection stretch blow molding (injection stretch blow molding) [26, 27]. Stretch blow molding is a kind of blow molding that is stretched by biaxial orientation. Its process is to first melt the raw materials at an ideal processing temperature and then use extrusion molding or injection molding to make a mold. There are two ways to make the parison reach the stretching temperature, one is to directly cool to the stretching temperature from a state above the stretching temperature, and the other is to After forced cooling, it is heated to the stretching temperature. Finally, the heated parison is longitudinally stretched by a stretching mandrel and is inflated with compressed air to form a product.
Extrusion stretch blow molding and injection stretch blow molding can be divided into one-step and two-step methods according to the process. The one-step method means that the three processes of parison preparation, stretching and blow molding are completed in sequence in the same equipment. The parison is used as a semi-finished product in the production process, so the one-step method is also called the hot parison method. The two-step method manufactures the parison prepared in the first step, which becomes the semi-finished product to be processed after forced cooling, and then preheats, stretches and blows the cold parison on another equipment through the second step, and finally makes The finished product, the two-step method is also known as the cold parison method. Therefore, the current stretch blow molding equipment is mainly divided into the following four types:
(1) One-step extrusion-stretch hollow blow molding equipment is mainly used to process PVC, etc.
The process of one-step extrusion-stretch blow molding equipment is mainly divided into three stations. In the first station, the thermoplastic raw material is melted and kneaded, and extruded by an extruder. After reaching a certain length, the pre-inflation die is closed and cut to obtain a parison; in the second station, the parison is pre-inflated. The mold is inflated by compressed air, and the neck is compressed into a thread shape; in the third station, after transferring to the stretching and blowing mold, the parison is axially stretched by the mandrel, while the compressed air is blown into the mold. , the product is released from the mold after cooling.
(2) Two-step extrusion stretch blow molding equipment, mainly used to process PVC and PP, etc.;
two-step extrusion blow molding equipment is divided into two parts: parison preparation equipment and stretch blow molding equipment. The parison was prepared using a conventional extruder. The main steps of the molding process of the stretch blow molding equipment are: first, the preformed parison is heated, then transferred to the stretch blow molding mold, and the parison is axially stretched by inserting a mandrel from the neck end. At the same time, after blowing in compressed air for inflation, the mold is passed into a cooling medium, so that the product is rapidly cooled and formed.
(3) One-step injection stretch blow molding equipment, mainly used to process PET and RPVC, etc.
The process of one-step injection stretch blow molding, in addition to the parison injection molding station, is different from the one-step extrusion blow molding process. The process of stretch blow molding is similar, and it is divided into four stations: injection, reheating, stretch blow molding, and product removal.
(4) Two-step injection stretch blow molding equipment, mainly used to process PET, etc.
Also, similar to the two-step extrusion stretch blow molding process, the two-step injection stretch blow molding process uses
A comparison of one-step and two-step injection stretch blow molding is shown below in 1-1 .
|Craft||One step||Two steps|
|Footprint and configuration||a) The equipment cost is low and the floor space is small; b) There are few operators and few auxiliary devices.||a) The equipment cost is high and the floor area is large; b) There are many operators and many auxiliary devices.|
|Molding requirements||a) The compressed air pressure is below 1MPa;|
b) Continuous molding from parison to plastic bottle products, blow molding
There is little chance of damage during this period.
c) No need for secondary heating, higher energy efficiency;
d) The injection molding cycle does not match the blow molding cycle, and the production capacity is low;
e) The quality of the injected parison cannot be checked.
|a) The compressed air pressure is below 2MPa;|
b) The preparation and blow molding of the parison are carried out separately in two equipment, and the parison is prone to damage during transportation;
c) It needs to be heated twice, and the heating conditions of the two moldings can be controlled separately, which is beneficial to ensure the quality of the products.
but lower energy efficiency;
|Scope of application||a) It is suitable for the manufacture of small-volume plastic bottles; b) It is suitable for on-line operation with the filling machine; c) It is suitable for small batch production.||a) Applicable to the manufacture of plastic bottles of various specifications; b) A large stretch ratio is acceptable; c) Thick-walled plastic bottles can be manufactured;|
d) High production efficiency, suitable for mass production.
At present, the more mature manufacturer of one-step stretch blow molding equipment is SIPA in Italy, while
The ECS FX 20/80 EVO blow molding machine of the ECS series  can produce 1L plastic bottles with a diameter of Ф38mm.
Can reach 36000BPH (bottles per hour), as shown in Figure 1-2 is the structure of ECS FX 20/80 EVO blow molding machine.
Excellent foreign two-step blow molding equipment companies include Canada’s Husky Company, France’s Sidel Company and Germany’s Krones Company. Husky Company has been monopolizing the production technology of multi-layer co-injection PET preforms internationally.
With the CoolPik cooling and handling system, the inner and outer surfaces of the preform can be cooled evenly for 4 times, increasing the injection speed.
In addition, Husky has also launched the H-PET AE all-electric system, which is simpler and more flexible in design and more efficient in production. Sidel’s Combi series machine is an integrated PET bottle blowing, filling and capping unit, of which the Combi34xs can produce small bottles with a capacity of 0.2L~0.7L, and the production capacity can reach 61200BPH. Krones’ Contiform SK series can blow small bottles with a capacity of 0.75L, and can support 30 and 40 blowing stations, each station can blow up to 1500 bottles per hour, so the production capacity of the whole machine can reach 45000~60000BPH[6 ].
Linear and rotary PET blow molding machines
At present, most common blow molding machines on the market use a two-step production process, which are mainly divided into two types: linear blow molding machines and rotary blow molding machines. The comparison between linear blow molding machines and rotary blow molding machines is as follows .
|Linear type||Rotary type|
Lower price cost;
Due to the influence of factors such as the structure of the transmission chain, the
PET bottles need to be equipped with different types of linear machines, so the compatibility is general;
The working mode is intermittent production, and the blowing direction is reverse blowing; the number of mold cavities is small (4~16);
The mold opening structure is driven by a servo motor, and the heating chain is driven by a cylinder for intermittent motion;
Clamping driven by hydraulic or pneumatic; stretching mechanism driven by pneumatic;
The billet feeding and bottle feeding are realized by pneumatic clamp structure;
Suitable for low and medium capacity customers.
|Higher output; higher price;|
The same equipment can produce PET of different volumes and finish
bottle, so the compatibility and stability are better;
The working mode is high-speed continuous production, and the blowing direction is positive blowing: the number of mold cavities is large (6~30);
Driven by a geared motor, the synchronous belt drives the infeed and out of the bottle to run synchronously;
Adopt pin or swing mode locking
Adopt servo-driven or pneumatically-driven stretching mechanism; cam structure control is used to achieve synchronization of feeding blanks and bottles:
Equipped with high pressure gas recovery system: suitable for high production customers
The structure of the linear blow molding machine is shown in Figure 1-3 below. The linear blow molding machine is divided into 5 parts: the feeding and conveying device, the reheating device, the feeding and conveying device, the stretch blowing device and the discharging device.
Foreign manufacturers of rotary blow molding machines, represented by French Sidel, German Krones and Italian SIPA, have a larger market share. Sidel’s SBO Highspeed blow molding machine has a production capacity of 48000~64600BPH when blowing containers with a maximum capacity of 0.75L. Krones’ third-generation rotary blow molding machine Contiform 3 series can blow PET containers with a capacity of 0.1~0.3L, of which Contiform 328 can produce up to 63000BPH at the maximum mechanical power. The SFR series is a rotary blow molding machine launched by SIPA, in which the SFR 24 EVO can reach 24 blowing cavities with a production capacity of 50400BPH. The domestic rotary bottle blowing machine is represented by the PET automatic rotary bottle blowing machine developed by Guangzhou Tech-Long Packaging Machinery Co., Ltd., which has reached the leading level in the industry. The single-mould output can reach 1500~1800BPH. When the CPPX22 of the machine blows 0.2~0.77L containers, the production capacity has reached 39600BPH.