Chinas plastics extrusion molding machine and auxiliary machinery development present situation and the technology level of analysis

Half a century, China's plastics industry has experienced from scratch, from small to large, the process of development of especially to get high speed development of reform and development for 20 years, classes and complete industrial system has been developed, from the production has the world advanced level. According to relevant data, the production of plastic raw materials for 7.6 million t, 1999, second only to America, Japan, Germany, Korea, fifth in the world: the production of plastic products has more than 1500 tons, second only to the United States, ranked second. Plastic machinery industry is the industry technology and equipment to the plastics industry, the strong market demand to promote the development of plastics machinery industry. In 2000, for example, China's plastics machinery gross industrial output value is 8.528 billion yuan, import equipment cost of foreign exchange l3 - l5 $, cooperated more than domestic output. Including extrusion production units 7784 units, 844 sets of synthetic parallel twin-screw extruder, according to the 1255 sets of parallel and conical twin-screw extruder, the extruding unit imported 1817, at a cost of $116 million, 1625 sets of exports, foreign exchange earning $015 million, the product's overall technical level is equal to the level of advanced countries in the eighty s. There are, of course, has a group of the ninety s and even in today's international leading level of the product, but some specificity strong high-tech products still need to rely on imports. According to customs statistics, in recent years, China's imports of extruder shows a decreasing trend year by year, in 2000 than in 1999 to import the Numbers decreased by 5.3%, cut their spending by 32.7% in foreign exchange, and sets a 73% reduction in exports, foreign exchange earning is increased by 12.3%, indicating that domestic extruder topping technology has improved, the export price is relatively higher.

In plastic processing industry in China, almost 1/3-1/2 is done through extrusion molding of plastic products. As the second categories of products of molding machine, extrusion moulding of the unit production and sales accounted for about 20-25% of the plastic machinery, its manufacturer located in machinery, light industry, chemical industry, petrochemical, building materials, military industry and other industries, more geographically concentrated in plastic processing industry developed regions, such as jiangsu and zhejiang, liaoning, shandong, guangdong and other coastal areas. 124 main machines in enterprise gross industrial output value is 3.87 billion, has accounted for more than 70% : southeast coastal national production extruder manufacturers more than hundred, mostly private or township and village enterprises, accounting for about 60% of plastic machinery manufacturers, the variety of extruder account for 30% of the varieties of plastics machinery, the proportion and rising trend year by year. Over the country each year to produce 300 sets of > extruder unit manufacturer only three, four, most of the enterprise can low grade of old products, it is difficult to achieve economies of scale, especially in the control level, efficiency, accuracy, reliability and complete sets of large gap compared with developed countries. Due to the professional level and the product technology content is low, determines the low value-added products, so that the enterprise's overall efficiency is not high, in the international competition at a disadvantage.

1. The conventional single screw extruder unit current situation and the analysis of technical level

In the performance of conventional single screw extruder unit in our country has to produce the screw diameter of 30 12-30 250 mm a variety of specifications, all kinds of extrusion unit, too much length to diameter ratio in the range of 25 to 30. Some new type of mixing elements such as separation, barrier, FenLiuXing, variable flow channel and flow beam position transformation has been widely used said refining components such as: screw top speed: large diameter of 30 150-30 200 extrusion machining olefin material for 50 to 75 r/min, heat-sensitive materials such as PVC processing for 5-42 r/min, a diameter of 30 below 30 small machine olefin material is l60-200 r/min, when processing heat-sensitive materials such as PVC for 18 - l20r/min: Beijing university of chemical industry developed 30 l2mm portable single screw exhaust extruder to 1200 r/min. And single screw extruder screw minimum 30 6 mm diameter, maximum 30 700 mm, maximum length to diameter ratio of 60. ChiBei Japanese company 30 30 highest single screw extruder screw speed of 3000 r/min, extruder, 300 kg/h, actual production is much higher than our machines with specifications l4kg/h level.

Due to the conventional single screw extruder, compared with other extruder has the advantages of simple structure, strong and durable, easy maintenance, low cost, easy operation, etc. In a reasonable period of time still has great market in our country, so how to make the conventional single screw extruder of high quality, high efficiency, functionalization, the enormity of the task is still a molding machine research workers in China.

2. The special status of extruder and the analysis of technical level

In the special research field of extruder, the our country the general scientific and technical workers efforts, in some of the major models, such as exhaust extruder, tandem mill screw extruder, reciprocating pin extruder of snail, foaming extrusion machine, with the melt gear pump extruder, tandem multistage extrusion machine, planetary screw extruder, etc are manufacturers in China, has the independent research and development ability, and enjoy independent intellectual property rights, at present already entered the stage of series is developed. South China university of technology, invented and developed plastic electromagnetic dynamic plasticizing extruder and series of products, has put into mass production. Beijing university of chemical industry the latest successful development of three kinds of special extruder 30 l2 portable high-speed exhaust extruder, 30, 28 melt gear pump extruder and a tandem mill CPJ75 / l35 extruder.

In conclusion, you can see that after years of efforts, our country in the special extrusion molding technology and equipment level of research and development ability and the international advanced level of the gap is not very big, some main models of new type mixing equipment basic can production, domestic in some areas and the breakthrough. But how to convert prototype to finalize the design product, and then implement series production, still needs a period of time.

2. Different to the rotating twin screw extrusion molding machine analysis of the status quo and technology level

3.1 to rotation parallel twin-screw extruder

Differential rotating twin screw extruder has many types, can be divided into two categories, parallel and taper, the former two screw axis parallel to each other, the latter two screw axis intersect in a point of view. Currently popular parallel differential twin screw extruder is in the longitudinal and meshing area are more closed, namely type conjugate. Conical twin screw extruder with mesh type parallel vision to the working mechanism of the twin screw extruder are basically the same. If to design it into longitudinal and meshing area of the spiral groove is closed, then its transport capacity and build pressure ability is very strong, because of its feed end between the two screw axis have a larger space, can be used in a large thrust bearing and gear torque distribution, which can bear high torque and high thrust load, very suitable for hard PVC extrusion molding of class products. As a result, the current domestic PVC products mostly used in extrusion forming conical twin screw extruder. But when the screw diameter is large enough, the conical twin-screw extruder need big size of the thrust bearing and gear torque distribution, makes the machine structure is too pang fire, so large equipment with parallel to the twin screw extruder. Tandem bearing design and manufacture has not become a problem, thus conical and parallel twin-screw extruder manufacturing difficulty is narrowing differences between two transmission system, a prominent problem is conical twin screw hin machine screw and barrel of the processing and manufacturing is difficult, and the wear is larger, the manufacturing cost is higher than parallel confidential, so the screw diameter in 30 to 55-80 - mm within the scope of the differential twin screw extruder with conical twin-screw machine. And a diameter of 30, 80 or more using parallel to the double screw machine, diameter of around 30 30 parallel to the double screw machine, used for laboratory and other occasions. Differential twin screw hin extruder and single screw extruder, the main difference between two points: first of all, they are conveying mechanism is different. Material transfer in single screw extruder is drag flow, U.S.A delivery process of friction drag, the melt conveying section for viscous drag, new material and the size of the coefficient of friction between the metal surface and the viscosity of the melt material to a great extent, determines the single screw extruder conveying ability strong and the weak: the mesh type differential twin screw extruder in the transfer of a material is a positive displacement conveying, with the rotation of the screw, the material being mutually meshing thread mandatory to move forward, the degree of the positive displacement conveying depends on a screw screw arris and another degree of close to the screw of the spiral groove. Closely meshing with a vision to the rotating twin screw extruder can obtain maximum positive displacement conveying.

Second, the velocity field of both is different. Velocity distribution in the single screw extruder are relatively clear and easy to describe, in the twin screw extruder is quite complex and describe the difficulties, this is mainly due to the meshing twin screw extruder in existence. Many researchers by ignoring the twin screw extruder meshing area leakage flow on the flow field, however, the leakage flow in meshing zone and mixing characteristics of twin screw extruder and the overall behavior has much to do, so in no meshing area leakage flow under the condition of the flow field analysis although has certain reference value, but with little value. Due to the complex flow in meshing zone makes the double screw extrusion machine has mixed fully, uniform heat transfer, melting capacity is strong, a lot of advantages such as exhaust performance is good, so there are still many researchers in order to more accurately analysis meshing area of the flow are doing unremitting efforts.

Compared with the single screw extruder differential twin screw extrusion machine has many advantages: (1) charging easier. Due to the twin screw extruder is to rely on principle of positive displacement conveying material, so you can join the viscosity is very high or very low material and strip material, paste, powder, etc. (2) the material stay in twin screw extruder for time is short, narrow residence time distribution, so the twin screw extruder is suitable for processing of heat-sensitive materials. (3) excellent exhaust performance. This type is meshing twin screw hin self-cleaning feature makes the material on the surface of exhaust section have complete update. (4) excellent mixing and plasticizing effect. (5) lower than power consumption. Than the power of twin screw extruder is about thirty percent lower than the single screw extruder. This makes the twin screw hin extruder has obvious advantage in energy saving, consumption reduction.

Two in the twin screw extruder screw rotation direction and degree of meshing, led to the synthetic rotating twin screw extruder and differential twin screw extruder rotating different pumping, mixing and flow mechanism, at the same time also determines the extruder the two different purposes. In the mesh type synthetic rotating twin screw extruder, the material flow in the spiral groove? Quot; Up "glyph spiral flow. A higher twin screw extruder rotating speed is higher, and makes the material by shearing action. These characteristics make synthetic double screw extrusion machine has excellent dispersion and distribution mix ability, narrow residence time distribution, good self-cleaning effect etc, thus is widely used in polymer compounding and blending, filling, (enhancement), exhaust (> waved off and reactive extrusion (polymer polymerization and reactive modification), etc. But compared with differential twin screw extruder synthetic double screw extruder, the low transmission efficiency, build pressure ability is bad, so generally cannot be used to direct extrusion molding. If you want to obtain high extrusion pressure and needs in the downstream of by polymer melt gear pump or second order single screw extruder, it makes the rise in the cost of machinery and equipment.

In mesh type parallel to the rotating twin screw extruder, the material being closed around each screw type C in the small room, similar to the positive displacement pump delivery. Differential twin screw extruder rotating speed is low, material shear calorific value is small, so it demands for material thermal stability is not high, can be operated in the lower limit of material ChengGangMan degree, so it is not easy to break down the material, especially suitable for heat-sensitive materials (PVC) plastic processing. Compared with twin screw hin same extruder, differential twin screw extruder, high transmission efficiency and exhaust effect and the fusion effect is good, the material of dispersive mixing effect is poorer, but build pressure ability strong, and can be used to direct extrusion products. Other differential twin screw extruder especially suitable for the processing of PVC powder, powder can be added directly and eliminate granulation process, make the products costs fell by about twenty percent. Differential rotating twin screw hin extruder is mainly used for extrusion of PVC pipes, profiles, sheets and granulation.

In recent years, differential rotary double screw extruder, both at home and abroad get the development by leaps and bounds. Now different to overseas the research focus of twin screw extruder to enlarge its application scope, improve the technical performance indicators, improve the compatibility and the application of advanced measurement and control system of the unit.

Compared with the developed countries, our country in the design and manufacture and application of twin screw extruder is a big gap. Domestic development and research work of screw extruder started relatively late, so the product is low, low degree of seriation, most of the product technology level, the precision of the screw, barrel, machine performance and quality and the development level of the developed countries have a certain gap. At present, the production of differential rotating twin screw hin extruder for conical twin-screw extruder, parallel to the twin screw extruder is rarely, and more for medium and small, needed for the domestic large differential twin screw extruder almost all rely on imports. In the design and calculation of the twin screw extruder and manufacturing technology, there are still many difficulties to overcome, which restricted the our country the development of the double screw extrusion technology and equipment.

With the development of national economy, large plastic pipes, profiles, plate in the petrochemical, building, agriculture, national defense and other fields increasingly extensive application. Large parallel differential twin screw extruder is developed will be more and more attention.

3.2 to the rotating conical twin screw extruder

Conical twin screw extruder has been for more than thirty years since 1967, the basic structure of screw has experienced three forms: normal, double cone type, high efficiency double cone type.

(l) type

Normal is the primary structure of the conical twin-screw form, its characteristic is: screw big end and small end since the diameter is less than 2, screw groove depth along the full length is constant. Austria Cincinnati Milacron company CM series screw injection before the ninety s.

(2) double cone punishment

Double cone is Germany krauss Maffei company developed on the basis of normal structure, its characteristic is: screw big end and small end diameter than in 2, big end screw groove depth, small end screw groove shallow, screw groove depth along the screw length gradient, the ratio of the diameter and the spiral groove is changeless, constitutes the outer diameter of outer cone Angle and screw groove bottom diameter of the inner cone Angle. Due to the charging period of a normal spiral groove depth deep, so add capacity is big, the screw surface area is big, stay cold material for a longer time, increasing the heating heat transfer to the material, is advantageous to the material, such as the company had to KMD a KK series screw.

(3 > efficient double cone

High efficiency double cone is Cincinnati Milacron company in the late eighty s on the basis of the design principle of the double cone. Its characteristic is: screw big end and small end diameter is larger than 2, screw groove depth along the screw length gradient, screw length than double cone extended appropriately. This makes the material in the feeding section in a prolonged heating under the action of outside, can fully absorb heat, speeds up the heating, promote the plasticization. Feeding screw groove volume and the increase of surface area not only means the extrusion production, and it also means that the application of high flexibility, such as CM company CMT series in the ninety s. Efficient double cone is referred to as the advent of conical twin screw extruder on the development of dramatic technological progress, the extrusion production was the same specification type double or more than double.

In either in the form of a screw, the screw design at home and abroad are in the stage of experience design. Because of the conical twin-screw taper is small, on a short length of screw can approximatively thought to parallel twin screw, so can use parallel twin-screw extruder calculation formula of approximate calculation. For screw hin paragraphs parameter design, it is only to give experience design scope: to prevent the screw bite, only gives the qualitative solution: increase the lateral clearance between the two screw. Throughout the domestic production of conical twin-screw extruder is not hard to find the fact that the vast majority of manufacturers of products mainly rely on foreign prototype of surveying and mapping.

Is domestic in terms of the overall level of the conical twin-screw extruder, technical level is still low, low extrusion amount, inadequate plasticizing, large energy consumption, high failure rate. Some companies have begun to the original model are relatively backward technical renovation, the normal cone form update for efficient double conical twin-screw. In conical twin-screw extruder is a breakthrough the application field of research, Beijing university of chemical industry has successfully use it for explosives, electric carbon electrode material extrusion molding.

4. The pipe molding equipment analysis of the status quo and technology level

Plastic tubing compared with the traditional materials such as metal, cement, with light weight, corrosion resistance, low thermal conductivity, insulation performance is good, the lining no scale, small flow resistance, no rust, easy coloring, easy processing, no need to coating, construction convenient installation and maintenance. Therefore in the construction, agriculture, chemical industry, municipal, medical and health care by the widely used in various fields of national economy, demand is increasing year by year. In all kinds of pipes to rigid polyvinyl chloride (UPVC) pipe proportion is the largest. UPVC pipe application field is largest construction. In foreign countries, the largest diameter can reach l000mm, increasingly used in water supply project. 30 200-30 large pipe of 630 mm. In Europe, America and Japan accounted for about 70-80% above. The application field of UPVC pipe is not the same, in the United States, more than half of the UPVC pipe used in the pressure pipeline, in Japan, UPVC drainage pipe application field is largest equipment and pipes and so on. In our country, UPVC pipes have been in shenyang, tianjin, Shanghai, fujian, jinan and Harbin city applications, mainly used for drain, storm sewer, and threading pipe, but share is smaller. PE pipe is mainly used in industrial sewage pipe, gas pipe. Building wire threading protection pipe in our country 90% used the plastic pipe, plastic pipe wall storm sewer 50%, urban water supply pipe plastic pipe in the utilization rate of 50%, by 2010 China's new 80% residential indoor drainage pipe with plastic pipe, plastic pipe in the pipe market share will reach 50% in the country.

Production of our country and different application fields in the European plastic pipe proportion see table 2. By contrast, in the table of our country in terms of building drainage pipe, electrical casing, plastic pipe application is better, less application in terms of buried pipes. With the development of city construction in our country, drainage, industrial drainage and drainage of life and with the growing demand of large-diameter plastic drainage pipe transmission. According to experts predict? Quot; During 15 ", the investment for urban drainage about l200 one hundred million yuan, the sewage treatment capacity to 40% by 2005, according to the national chemical building materials "fifteen" plan and 2010 development plan outline ", "20% of the urban drainage pipe using plastic tube", need plastic tubing dosage is about l l t, as the urban drainage pipe buried in the ground, mainly bear external pressure effect, therefore, must have a high ring stiffness. And made of PE and PVC double-wall corrugated pipe than the solid wall pipe material saving 50-70%, and has a large ring stiffness and moment of inertia, and thus be more used.

Manufacturing method of double-wall corrugated pipe has a direct extrusion method and winding molding in two. Production line is composed of one or two of the former extruder by double-wall molding head out internal and external layer of tube billet, on crawler corrugated pipe forming machine, pipe under the certain pressure or vacuum adsorption, was 40-70 of continuous traction hough module, cooling, finalize the design as bellows. In recent years in foreign countries have already not hough module fixed on the track, but by "edge type design" national it on the operation platform, hough corrugated mould along track cycling sports, in the molding area, along the medial orbital module for slow moving, leave forming workspace, along the lateral orbital module for quick returns. Edge type has the advantage of less number of modules required, can save investment and energy consumption, especially for large diameter double-wall corrugated pipe production.

Winding molding in principle is: through the extruder head out different cross section shape of hollow ribbon parison and wrapped it in a plastic pipe wall light or wrapped in overlapping each other in diameter can be adjusted on the rotating cylinder clamping fixture, and then through the roller compaction, welding compound, the final cooling stereotypes into double-wall corrugated pipe. This method has the advantage of production it is easy to change the diameter of the bellows in the investment cost is low, the disadvantage is that take it welded seam welding performance is poor and difficult to detect, production efficiency is low, can only be used on the occasion of double-wall corrugated pipe sealing performance requirements is not high. At present, our country of the two kinds of double-wall corrugated pipe production technology and manufacturing technology have been mastered, and finalize the design product, manufacturers have dozens, larger output specifications for 30 51-102 mm, 30 individual manufacturer can produce 30 300-30, 600, is mainly used for building the exhaust pipe, agricultural drainage and communications cable sheath. More than 500 mm double-wall corrugated pipe few factory can supply, but more than 30 1000 mm large diameter double-wall corrugated pipe production. In buried pipe laying process and installation, connection technology is still in the test on the groping stage, so far has not yet to develop a national construction and acceptance standard, influence the speed of popularization and application. Coma in foreign countries, such as Canada company can produce pipe diameter of 3 m's three-layer composite double-wall corrugated pipe. Plastic tubing used for 56.2% of the total consumption in the drainage pollution of the city. Therefore, strengthening the application and experimental study on the buried pipes, manufacturing technology and equipment research, suitable for the situation of our country as soon as possible the buried pipes laid technology norms and standards, on the agenda, the work has been the department concerned experts and leadership attaches great importance to. We can expect in the field of study, the state will have more people.

In the new plastic pipe molding equipment, compare with prospects of market prospects and development besides double-wall corrugated pipe production line, the author thinks that there are silicon core pipe, PVC core layer foam pipe and agricultural sprinkler irrigation and microspray irrigation pipe three categories.

Silicon core pipe is made of a total of extrusion method of extrusion double-wall pipe, the outer wall to HDPE as the main raw material, the thickness of the lining is about 0.5 2 mm thin core layer containing silicon, plastic, mainly used for optical cable sheath. As the core layer wall has a permanent prelubricated performance, when the gas blowing method in optical fiber cable, lubricate the anti-sticking effect, once through the length of the cable can be up to thousands of meters, in the site construction can make the cable and casing thousands of meters without connectors. Thus laid high efficiency, low cost, communication quality can be guaranteed. Silicon core pipe has now become the subject of global optical cable sheath, introduced into China since 1996, now has more than ten enterprises production, production capacity has reached 30000 t to 2000, the domestic silicon core pipe extrusion equipment are available, predicts 2005 silicon core pipe market is about 6-80000 - t. With China's railways, highways and the high-speed development of optical fiber communication network, silicon core exchange equipment market is very attractive.

PVC core layer foam pipe is in a total of three layers of tube extrusion of PVC extrusion method, its outstanding characteristic is light. Its middle layer is the core layer foam layer, the density of just 0.7-0.98 / cm3, inside and outside two layer foaming, pipe density of 0.9-0.9 / cm3, lighter than PVC solid wall pipe weight about 20-30%. In addition to the light, it is better than the solid wall pipe impact resistance, rigid eight times for the latter, and the ring to the bending mode is more than a decade, long service life than the latter degree and wide use and good dimensional stability, can be in when it's minus thirty - l00 ℃, and the solid wall pipe can only be used under 15 to 60 ℃ below zero. PVC core layer foam pipe or has good heat insulation effect, than not foaming 35% lower solid wall tube heat transfer efficiency, and thus can significantly reduce the running noise, particularly suitable for building drainage. Due to the light, and the core layer can be added to a large number of recycling material stays a beautiful appearance, so PVC foam layer core pipe production of low cost and convenient transportation, has more and more get the welcome of construction market, and is widely used in building drainage engineering, industrial anti-corrosion, liquid transportation and agriculture irrigation and drainage, etc.

PVC core layer foam pipe spell line usually includes a extrusion foam core layer of the extrusion machine and one or two out of inner and outer layer of extruder, them with their own closed cooling system and quantitative feeding device, controlled by the computer independent (or concentration) out of the whole production process. Due to the core layer with SAP accounts for about 70% of the total, requirements than its main extruder extruder screw diameter too. PVC pipe core layer is one of the core technology of co-extrusion composite reasonable design of the nose, it consists of a feeding and pipe mould, complicated structure. Feeding block respectively with the main extruder and the extruder with hough module connection, molten compound pipe mould to complete the three layers of material.

In light pipe production, the fastest growth rate of the PVC core layer foam pipe, the main reason is simple, economic, production technology and excellent performance. The development history of PVC pipes and solid wall corrugated pipe, double-wall corrugated pipe and core layer foam pipe three stages. In the early 1980 s, France atofina, the company has developed plastic core layer foam pipe, South Korea in the ninety s introduced this technology, entering the Chinese market in 1995. The world's only France, Korea, Germany, the United States, Austria and other countries have the ability to output a complete set of technology. In Europe, in 1997 produced about 1997 t PVC household and industrial pipes and hoses, etc., of which about 25% (214000 > as the core layer foam pipe. In our country, at present, shenzhen, foshan, wujiang, longkou, has imported equipment in the production, the huge market prospects will encourage domestic PVC core layer foam pipe production equipment research and development quickly.

Agricultural irrigation pipe and microspray irrigation is an important part of water-saving irrigation equipment. As is known to all, China is one of the world's 12 PinShuiGuo, per capita water resources is 2300 cubic meters, was only about a quarter of the world average, and agricultural irrigation water accounts for 70.80% of the total water consumption in our country, the national irrigation district agricultural water utilization rate is only 30.40% (70.80%) developed countries. Therefore, how to "open source" "throttling", to solve the water crisis in our country, has become a common concern of the nation. The fifth plenary session of the party's 15 points out "sustainable utilization of water resources is a strategic issue of economic and social development in our country, the core is to improve the efficiency of water use, put water-saving prominence". In agricultural irrigation water saving measures, the use of sprinkler irrigation area of 44% of the world, microspray irrigation area of 27% of the world, a spray of micro-irrigation equipment manufacturing quantity to Europe, America Asia accounts for 70.80% of the world, Israel adopts micro irrigation area has accounted for 69.7% of the total irrigated area, and only 0.5% of our country, so the irrigation pipe, microspray irrigation pipe production technology and equipment development research should be a cause of the molding machine industry in our country seriously enough.

Micro-irrigation technique in our country has experienced the introduction of the development of drip irrigation equipment, digestion, absorption and application of pilot and equipment development, product improvement, to expand the pilot and direct introduction of foreign advanced technology, high starting point development of micro-irrigation equipment products such as phase. Micro-irrigation production has reached dozens of enterprises, such as Beijing luyuan plastic joint, hebei longda irrigation equipment co., LTD., shandong laiwu plastic products co., LTD., xinjiang yao industry co., LTD., gansu province light industry machinery factory, the main products are pipe type drip irrigation pipe pressure compensation, inner insert flat head drip irrigation belt, inner insert character drops head yao tube, unilateral pressure jewels drops drip irrigation belt and so on. Most companies rely on import technology and equipment for production. Some broad home by the way of surveying and mapping of generic technology level is low, single product variety, the narrow scope of application. Within insert column head drops drip line as an example, the domestic equipment prices for imported equipment of 1/10-1/8, but the speed is only 8-10 m/min, the individual can be up to 30 m/min, and imported equipment is up to 100 m/min. In the drip irrigation pipe production should solve the problem of two core technology, namely, how to ensure the uniformity of drip water system and measures to make drip in the long-term use does not produce clogging. According to certain spacing with drip irrigation tube, usually each drip water yield of about 2.4 l/h, in irrigation, the error must not exceed 20% of drip water yield, and in the drip irrigation pipe production with l00 m/min speed set the drip in the casing wall, which requires the drip irrigation pipe production equipment is very precise. Production equipment set polymer materials, optical, mechanical, electrical, control and other modern technology as a whole, the development of the it need professional knowledge, the combination of many subjects, such as machinery, electronics, agriculture, water conservancy, materials, etc. In order to better meet the domestic users to the huge demand for sprinkler irrigation and microspray irrigation pipe production equipment, the enterprise should be combined with university, academy, giving full play to the advantages of production, to develop a higher technical level, better technical performance, and has more functions, quality and cheap sprinkler irrigation and microspray irrigation pipe production machinery.

5. The present status of sheet molding equipment and technology level of analysis

In sheet molding equipment, with hard PVC the most rapidly growing and micro foaming decorating plate processing equipment technology is also the most complex, in this only as a typical are analyzed.

Rigid PVC micro foaming decorating plate because of its small density, there is a fine bubble pore structure, internal surface similar to natural wood, so is also called the "synthetic wood". Is a new type of chemical building materials. Through the special processing formula, process and mould, to produce more design and color, multi-function, many varieties of products. Realistic imitation wood, it can be like wood saw, hammer, planer, adhesive, but in a waterproof, moisture proof, fire prevention, insect-resistant, sound insulation performance, etc, and is better than that of wood, is a kind of ideal building decoration materials, which can be widely used in ceiling, partition, mural ark, shop fronts, merchandise display decorate material: ships, trains, planes, car inner decoration materials: hotel, office, residential indoor metope: used to make all kinds of layer board, stands in the advertising industry, advertising, public markers: using it for making furniture, computer desk, furniture industry fast table: in the field of environmental protection to make the chemical anti-corrosion tank, ventilation pipes, etc. According to relevant data, the western developed countries such as Italy, Austria, the foamed board production accounts for more than 15% of plastic products, the dosage of the 2000 European PVC micro foaming products is 168000 t, the United States is 75000 t, the dosage of each year is increasing at the rate of 7% and 17%, respectively. Rigid PVC low foaming technology research abroad began in the 1970 s, eighty s realize industrialized production. French Vigine Kuhlman company development Caluka method (also known as the crust foaming method) is a breakthrough of low foaming technology, introduced in the ninety s co-extrusion core layer foaming method, due to its processing equipment configuration not only can produce free foaming plate and slightly introverted foam sheet, but also can be extended to other core layer fill the recycled material and multilayer extrusion plate processing equipment, so has been developing rapidly in recent years, is considered to be one of the most promising technology.

In terms of micro hard PVC foam sheet molding equipment, mainly in Europe differential rotation parallel and needle conical twin screw extrusion line is given priority to, major manufacturers have a German baden field (Battenfeld) and Klaus murphy (Kmuss Maffia) company, Italy's baoshan (Bausano) and eminem (Amut > company. In the early 1990 s, our country jixi, shenzhen, foshan, shunde, suzhou, guangzhou, hangzhou, Shanghai, wuhan and other places, respectively, the introduction of low foamed rigid PVC sheet production line, the article has more than 30, form the production capacity of 45000 t, about half of them are made in Taiwan, most of them adopt free foaming and molding Caluka method. Some universities and domestic manufacturers have to rigid PVC micro foaming mechanism, a lot of research on technological formulation and molding equipment, has accumulated a lot of experience. Its core technology is the formulation of raw materials, control of foaming process, the flow of the flow channel simulation and optimization calculation, cooling stereotypes parts development and production line of all control all process parameters (including the collection, display, storage, and feedback control).

6. Extrusion molding equipment development trend and countermeasures

Development trend of extrusion equipment for I can see there are the following:

6.1 high speed and high yield

For a long time, as main performance indicators of extrusion equipment for "high speed, high yield, has been the main development direction of extrusion molding machine, high output and price is most concerned about is not only the entrepreneurs, is also the goal of science and technology workers dream. 90 single screw hin extruder, for example, its production from 1961 to 1961 kg/h, increased by 1995 to 600 kg/h, yields 6.7 times for 34 years: WP company ZSK MC type synthetic parallel twin-screw extruder of ZSK MV from 1995 to 2001, six years the screw rotation speed increased from 600 r/min to l800r/min. The yield increased 2.5 times.

Extrusion machine high speed, high yield and therefore it can make the investors at a relatively low investment to obtain larger output and high q, but from a technical point of view, as the extruder screw hin high speed rotating speed also brought a series of difficulties to overcome, such as material residence time in the screw to reduce lead to uneven material mixing plasticization, material caused by excessive shear material rapid heating and thermal decomposition, extrusion stability control difficulty caused by extrudate geometry size, the relevant auxiliary device and the precision of the control system must be improved, the screw and barrel wear, need to use high wear resistance and high wear-resisting material, under the condition of the high speed reducer and bearing a series of problems such as how to improve their life...

6.2 high efficiency, more functional

Efficient performance of extruder is mainly in the high output, low energy consumption, low manufacturing cost. Last October in Germany "l5 International Trade Fair Platics Rubber ', on display at ZSK series synthetic parallel twin-screw extruder unit consumption (i.e., than nominal power) are less than 0.1 KWh/kg, and domestic about 0.15 0. L6KWh/kg: in terms of function, screw extruder is not only used for polymer extrusion molding and mixing processing, its use has broaden into food, feed, electrical carbon, electrode, the explosive fire, building materials, packaging, paper pulp, ceramics, etc. In addition, the mixing granulation and incorporated in the extrusion process for" one-step extrusion process ', is also worth attention. "One-step extrusion molding process in a shortened process, save energy, reduce equipment investment and area, reduce operating personnel aspects and so on than the traditional two-step process has obvious advantages.

6.3 more and more motors

In the extrusion molding equipment, in general, small general machine can produce in our country. Extruder in China in 2000 to production has reached 7784 units, 844 sets of the same flat double, to the flat double and cone double 1255 units, for the most part in the 1817 sets of imported extrusion molding machine is large, sophisticated machines. Because large-scale extrusion molding equipment can be realized, can reduce production cost, which in large twin-screw granulation unit, blown film machine, pipe extrusion unit has more obvious advantages. Focus on developing service for the national key construction of major technical equipment, large-scale ethylene project supporting one of the three major key equipment, large extruding and granulating machine group has relied on import for a long time, so we must speed up the localization process, can meet the needs of the petrochemical industry development. Motors can improve the value of products, such as multilayer co-extrusion composite films are need precise extrusion, and as one of the important ways to realize precise extrusion melt gear pump must intensify efforts to develop research one by one.

6.4 modular and specialization

Implement extrusion molding mountain equipment production, the "module? Quot;," professional "is the trend of The Times." Modular "production can adapt to the special requirements of different users, shorten the development period of new products, strive for more market share; and" specialization "" production extrusion equipment for each system module components can be arrange designated production even for global purchasing, to guarantee the machine quality, reduce cost, accelerate the capital turnover is beneficial. In our country, the extruder screw, barrel, reducer, heating and cooling system, lubricating system, feeding system, control system have a designated factory specializing in the production, it is surely right.

6.5 intelligent and networked

Extruder has developed countries widely used modern electronic and computer control technology, work station is equipped with screen monitoring, for the whole extrusion process parameters such as the melt pressure and temperature, paragraphs, body temperature, the main screw and feed screw speed, feed feed rate, the proportion of all kinds of raw materials, on-line detection parameters such as current voltage of the motor, and USES the microcomputer closed-loop control. Some companies have adopted the remote online studio, monitoring, diagnosis and control, network control was carried out on the extrusion molding line. This to ensure stability in the process conditions, improve the accuracy of the product is extremely advantageous.

7. To our country the development Suggestions of plastics extrusion molding equipment

(1) the new extrusion mixing technology and equipment development

Used for polymer blending modification on the current international new mixing equipment model there are three main categories, namely synthetic parallel twin screw hin extruder, reciprocating movable screw mixer and tandem mill extruder. With a higher parallel twin screw hin extruder domestic small and medium-sized can produce, but wan t level large imports all mixing extruding and granulating machine group, 2010 years ago in China for the introduction of this kind of exchange is expected to about $450 million. Reciprocating roller screw tandem mill, mixer, and the machine is for making polymer alloy high fill and high added value of necessary equipment, at home, they developed just in the prototype stage, few specifications, variety is not complete, almost all markets for foreign manufacturers monopoly.

(2) a vision of the large diameter pipe extrusion to parallel twin-screw extrusion unit, steel-plastic composite pipe extrusion unit and more than 500 mm large double-wall corrugated pipe extrusion unit, and the special plastic pipe material for the development of the research unit

(3) composite extrusion technology and equipment for the development of the research

Recently, multi-layer co-extrusion ultra wide geomembrane, packing drawing of flat membrane, construction of composite corrugated plate, the market demand of core layer foam sheet and pipe is large, the related research of forming technology and equipment must be cause enough attention.

(4) of the recovery and recycling of waste plastic technology and equipment development

Plastic products of "white pollution" caused by the natural environment, has affected the sustainable development of national economy in our country, so we must enhance the study of the recovery and recycling of waste plastic work, for those who recycle difficulties or recycling cost too much with functions of degradation products should be made of plastics.

(5) to upgrade conventional plastics processing equipment, improve the efficiency of production, and the level of self-control

Now foreign plastic different profile extrusion rate of 4 to 8 m/min, two-way stretch film drawing rate of 450 m/min, and domestic relative speed is only 1.5 2.5 m/min and l20m/min to upgrade the existing equipment modification, less investment, can have the effect of four two dial one thousand jins.

(6) strengthen the CAD/CAE/CAM technology application in the plastics industry research

The study can make the design of rubber and plastic machinery design, from the experience of time-consuming and costly test modified model to accurate, rapid and high precision modernization level, makes extrusion molding equipment manufacturing industry of our country in the fierce international competition.

(7) on-line detection and automatic control technology research

Developed countries digital, intelligent control and laser testing technology is mature, and servo system can achieve full online control extrusion unit, and connected to the on-line detection device, according to feedback control signal acquisition and storage of implementation, guarantee the stability of the process conditions, improve the accuracy of the product. In addition, the reliability of the electrical components research also nots allow to ignore, domestic equipment is an important cause of the high failure rate is poor reliability of the electric control system.

(8) the positive development of high efficiency, energy saving, environmental protection, extrusion molding device, limit development overcapacity long term product, selection, high material consumption and serious environmental pollution. With natural plant fiber and waste plastic as main raw material of wood plastic composite product extrusion technology and equipment, enough attention must be paid to the study, in PS, PE extrusion foaming equipment, restrict the use of CFCS in the production of eliminating ultra-thin plastic bags (less than 0.015 mm) production equipment, and encourage the development of waste plastics recycling and reuse as well as the development of degradable plastics processing extrusion equipment research.