Berita Syarikat

Pipa PPR Meningkatkan Kekuatan Mekanikal Untuk Meningkatkan Pengeluaran

2018-11-15

First, the basic principles of plastic extrusion

Plastic processing industry is a highly integrated technology industry. It involves the polymer chemistry, polymer physics, interface theory, plastic machinery, plastic processing mold, formula design principles and process control and so on. The theory of extrusion mainly studies the movement and change of plastic in the extruder. The relationship between the three physical states of the polymer,PPR Pipes the relationship between the screw structure, the plastic properties and the processing conditions of the polymer in the different temperature range under the action of a certain external force in the extruder. So as to carry out reasonable process control. In order to achieve the purpose of improving the production and quality of plastic products. Plastic polymer materials, heated at constant pressure, in different temperature range, there are glass, high elasticity, viscous flow of three physical state. General plastic molding temperature above the viscous temperature.

Second, polyolefin pipe extrusion molding process control

The control parameters of the extrusion process include molding temperature, extruder working pressure, screw speed, extrusion speed and traction speed, feeding speed, cooling and so on.

1. Pretreatment of raw materials

Polyolefin adalah bahan bukan penyerap, kandungan kelembapan biasanya sangat rendah, boleh memenuhi keperluan penyemperitan, tetapi apabila poliolefin yang mengandungi pigmen penyerap, seperti karbon hitam, kelembapan sensitif. Di samping itu, apabila penggunaan bahan dan pengisi, kandungan air akan meningkat. Kelembapan bukan sahaja menyebabkan bahagian dalam dan luar paip menjadi kasar, tetapi juga boleh menyebabkan gelembung lebur. Selalunya bahan mentah perlu dipersiapkan. Kegunaan umum pengeringan, juga boleh ditambah dengan fungsi dehumidifikasi yang sesuai dari aditif. Seperti defoamers. Suhu kering PE pada umumnya ialah 60-90 darjah. Pada suhu ini, PPR Pipa hasil boleh ditingkatkan sebanyak 10% hingga 25%.

2. temperature control

Suhu pengacuan penyemperitan diperlukan untuk mempromosikan plastikisasi bahan pengacuan dan aliran cair plastik. Bahan plastik dan kualiti dan hasil produk mempunyai kesan yang sangat penting. Penyemperitan Plastik Tetingkap suhu teoretik adalah antara suhu aliran kelikatan dan suhu kemerosotan. Julat suhu adalah luas untuk poliolefin. Biasanya di atas takat lebur, 280 darjah atau kurang boleh diproses. Untuk mengawal suhu pencetakan penyemperitan dengan betul, kita mesti terlebih dahulu memahami had suhu bahan yang diproses dan sifat fizikal hubungannya. Untuk mengetahui ciri-ciri dan undang-undangnya untuk memilih julat suhu yang lebih baik untuk pengacuan penyemperitan. Oleh itu, penetapan suhu harus mengambil kira aspek berikut: Pertama, polimer itu sendiri, seperti titik lebur, saiz berat molekul PPR dan pengedaran, indeks lebat dan sebagainya. Diikuti oleh prestasi peralatan. Sesetengah peralatan, bahagian suapan suhu pada hos mempunyai kesan yang besar pada arus. Sekali lagi, dengan mengamati permukaan tabung die tube penyemperitan adalah lancar. Sama ada gelembung dan fenomena lain untuk menilai.

The extrusion temperature includes the set temperature of the heater and the melt temperature. The heating temperature is the temperature provided by the external heater. The melt temperature refers to the temperature of the material between the front of the screw and the head.

Pengedaran suhu barel, dari zon makanan ke mati, mungkin rata, bertambah, berkurang dan bercampur. Terutamanya bergantung pada titik material dan struktur extruder.

Head set the temperature, in order to obtain better appearance and mechanical properties, and reduce the melt outlet expansion, the general control of the body temperature is lower, the machine head temperature is higher. The machine head temperature is high, can make the material smoothly into the mold, but the shape of the extruded material is poor, the shrinkage increases. Head temperature is low, the material plastic bad, melt viscosity, nose pressure rise. Although this will make the product too dense, after the shrinkage rate is small,PPR Pipes the product shape stability is good, but the processing is more difficult, from the mold expansion larger, the product surface rough. But also lead to increased backpressure extruder, equipment load, power consumption also increases.

The temperature of the die set, the temperature of the die and the core mold have an effect on the surface finish of the pipe. In a certain range, the die mold and the core mold temperature are high and the surface finish of the pipe is high. Generally speaking,PPR Pipes the temperature of the die outlet should not exceed 220 degrees, the melt temperature of the inlet of the head is 200 degrees, and the temperature difference between the inlet and outlet of the machine head should not exceed 20 degrees. Because the higher temperature difference between the melt and the metal will cause the shark skin phenomenon. Excessive melt temperature leads to die. But the specific decision to the actual situation.

Suhu leburan adalah suhu sebenar cair yang diukur pada akhir skru dan oleh itu pembolehubah bergantung. Terutamanya bergantung kepada kelajuan skru dan suhu setong setong. Had atas suhu mencair paip polietilena tersemperit secara umumnya ditakrifkan sebagai 230 darjah. Secara umum dikawal pada kira-kira 200 darjah lebih baik. Penyemperitan paip polipropilena penyejatan suhu mencecah biasanya 240 darjah. Suhu cair tidak boleh terlalu tinggi. Secara amnya pertimbangkan penurunan bahan, PPR Pipes manakala suhu terlalu tinggi akan membuat bahan paip sukar.

3. Pressure control

The most important pressure parameter in the extrusion process is the melt pressure, that is, the head pressure, in general, increase the melt pressure, will reduce the output of the extruder, leaving the product density increased, is conducive to improving product quality. But the pressure is too large,PPR Pipes will bring security problems. Melt pressure and the size of raw materials, screw structure, screw speed, process temperature, the mesh mesh number, porous plate and other factors. The melt pressure is usually controlled between 10 and 30 MPa.

4. Vacuum setting

Stereotipe vakum terutamanya mengawal vakum dan kelajuan penyejukan kedua-dua parameter. Biasanya dalam penampilan kualiti paip untuk memenuhi premis, vakum harus serendah mungkin, supaya tegasan paip adalah kecil, produk dalam proses penyimpanan ubah bentuk kecil.

5. cool down

Pembentukan penyemperitan paip polietilena dalam keperluan suhu air penyejuk pada umumnya rendah, biasanya di bawah 20 darjah, dalam pengeluaran paip PPR, perenggan pertama suhu boleh sedikit lebih tinggi, bahagian terakhir yang lebih rendah, mengakibatkan kecerunan suhu. Ia juga penting untuk menyesuaikan aliran air penyejuk. Alirannya terlalu besar, permukaan paip kasar, mengakibatkan lubang tempat. Alirannya terlalu kecil, Paip PPR permukaan paip untuk menghasilkan bintik-bintik yang terang mudah dilepaskan, seperti taburan yang tidak rata, ketebalan dinding paip tidak rata, atau bujur.

6. Screw speed and extrusion speed

Kelajuan skru adalah untuk mengawal kadar penyemperitan, hasil dan kualiti produk parameter industri berat. Kelajuan extruder skru tunggal meningkat dan kenaikan hasil. Kadar ricih meningkat dan kelikatan yang jelas mencairkan berkurangan. Adalah kondusif untuk homogenisasi bahan. Pada masa yang sama disebabkan oleh plastik yang baik, maka interaksi antara molekul meningkat kekuatan mekanikal. Tetapi kelajuan skru terlalu tinggi, beban motor terlalu besar, tekanan leburan terlalu tinggi, kadar ricih terlalu tinggi, daripada pengembangan acuan Peng, kemerosotan permukaan, dan jumlah ketidakstabilan.

7. Traction speed

Traction speed directly affects the product wall thickness, dimensional tolerance, performance and appearance, traction speed ratio to be stable, and the traction speed and pipe extrusion speed match. The ratio of the traction speed to the extrusion line velocity reflects the degree of orientation that the product may occur, which is called the draw ratio and must be equal to or greater than 1. The traction speed increases and the temperature of the cooling stereotypes is constant , Then the product in the sizing sleeve, cooling the water tank to stay in the time is relatively short, after the cooling of the finished product will also be more inside the residual heat, the heat will make the product in the process of pulling the orientation of the orientation structure has occurred ,PPR Pipes Resulting in a reduction in the degree of orientation of the article. The faster the traction speed, the thinner the wall thickness of the pipe, the greater the shrinkage of the finished product after cooling. The slower the traction speed, the thicker the pipe wall thickness, the more likely to lead to stowage between the die and the sizing sleeve. Destruction of normal extrusion production. Therefore, the extrusion process in the extrusion speed and traction speed must be well controlled.

8. On - line quality control and post - processing of pipe

Polyolefin-based crystalline polymers, the performance of the down-line tubing is different from the size and performance of the pipe product when it is delivered. The main reasons are, first, polyolefin melt cooling process to occur crystallization, crystallinity and crystal form and temperature and thermal history, the time to place. Second, just off the pipe temperature is usually higher than room temperature. Third, just off the assembly line of stress in the pipe. In order to achieve the stability of the performance and size,PPR Pipes the general polyethylene pipe should be placed off the assembly line for 24 hours, the polypropylene pipe to be placed after 48 hours, according to the corresponding standards for performance testing.