PPR Pipes Increased Mechanical Strength To Improve Production

Najprej osnovna načela ekstrudiranja plastike

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. Predobdelava surovin

Poliolefin je nevpojni material, ki ima običajno zelo nizko vsebnost vlage in lahko zadovolji potrebe ekstrudiranja, toda ko poliolefin, ki vsebuje vpojne pigmente, kot so saj, je občutljiv na vlago. Poleg tega se bo ob uporabi materialov in polnil vsebnost vode povečala. Vlaga ne samo, da je notranjost in zunanjost cevi groba, temveč lahko povzroči tudi mehurčke v talini. Pogosto je treba surovine predhodno obdelati. Splošna uporaba sušenja se lahko doda tudi z ustrezno funkcijo razvlaževanja aditivov. Kot so penilci. Suha temperatura PE je običajno 60-90 stopinj. Pri tej temperaturi lahko PPR cevi donos povečajo za 10% do 25%.

2. temperature control

Temperatura ekstrudiranja kalupa je potrebna za pospeševanje plastificiranja kalupov in pretoka plastične taline. Material plastike ter kakovost in donos izdelkov imajo zelo pomemben vpliv. Ekstrudiranje plastike Teoretično temperaturno okno je med temperaturo dovoda viskoznosti in temperaturo razgradnje. Temperaturno območje je za poliolefine široko. Običajno nad tališčem lahko obdelamo 280 stopinj ali manj. Da bi pravilno nadzorovali temperaturo ekstruzijskega oblikovanja, moramo najprej razumeti temperaturno mejo materiala, ki se obdeluje, in njegove fizikalne lastnosti razmerja. Da bi ugotovili njegove značilnosti in zakonitosti, da bi izbrali boljši temperaturni razpon za ekstruzijsko oblikovanje. Zato bi morala nastavitev temperature upoštevati naslednje vidike: Prvič, sam polimer, kot so tališče, velikost in porazdelitev molekularne mase PPR cevi, indeks taljenja itd. Sledi zmogljivost opreme. Nekatera oprema, dovodni del temperature na gostitelja, ima velik vpliv na tok. Tudi pri opazovanju cevi je ekstrudiranje površine cevi gladko. Ali je treba mehurček in druge pojave presoditi.

Temperatura iztiskanja vključuje nastavljeno temperaturo grelnika in temperaturo taline. Temperatura ogrevanja je temperatura, ki jo zagotavlja zunanji grelec. Temperatura taljenja se nanaša na temperaturo materiala med sprednjim delom vijaka in glavo.

The barrel temperature distribution, from the feed zone to the die, may be flat, incremental, decreasing and mixed. Mainly depends on the material point and the structure of the 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.

The melt temperature is the actual temperature of the melt measured at the end of the screw and is therefore the dependent variable. Mainly depends on the screw speed and barrel setting temperature. The upper limit of the melt temperature of the extruded polyethylene pipe is generally defined as 230 degrees. Generally controlled at about 200 degrees is better. Polypropylene pipe extrusion melt temperature limit is generally 240 degrees. Melt temperature should not be too high. Generally consider the degradation of materials,PPR Pipes while the temperature is too high will make pipe material difficult.

3. Pressure control

Najpomembnejši parameter tlaka v postopku iztiskanja je tlak v talini, to je tlak v glavi, na splošno poveča tlak v talini, zmanjša izhod iztiskanja, pri čemer se poveča gostota izdelka, kar prispeva k izboljšanju kakovosti izdelka. Toda pritisk je prevelik, cevi PPR bodo prinesle varnostne težave. Tlak v talini in velikost surovin, struktura vijaka, hitrost vijaka, temperatura postopka, število mrežnih očes, porozna plošča in drugi dejavniki. Tlak taline se običajno uravnava med 10 in 30 MPa.

4. Nastavitev sesalnika

Vacuum stereotypes mainly control the vacuum and cooling speed of the two parameters. Usually in the appearance of the quality of the pipe to meet the premise, the vacuum should be as low as possible, so that the pipe stress is small, the product in the storage process deformation small.

5. ohladite

Ekstrudiranje polietilenskih cevi pri zahtevah za temperaturo hladilne vode je na splošno nizko, običajno pod 20 stopinj, pri proizvodnji cevi PPR je lahko prvi odstavek temperature nekoliko višji, drugi del nižji, kar povzroči temperaturni gradient. Pomembno je tudi prilagoditi pretok hladilne vode. Pretok je prevelik, površina cevi hrapava, kar povzroči nastanek jam. Pretok je premajhen, PPR napelja površino cevi, da ustvari svetle točke, ki jih je mogoče enostavno odstraniti, na primer neenakomerna porazdelitev, neenakomerna debelina stene cevi ali oval.

6. Hitrost vijaka in hitrost iztiskanja

Screw speed is to control the extrusion rate, yield and product quality of heavy industry parameters. The speed of the single screw extruder increases and the yield increases. The shear rate increases and the apparent viscosity of the melt decreases. Is conducive to the homogenization of materials. At the same time due to good plasticization, so that the interaction between the molecules increased mechanical strength. But the screw speed is too high, the motor load is too large, the melt pressure is too high, the shear rate is too high, from the mold Peng expansion, the surface deterioration, and the amount of instability.

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. Spletni nadzor kakovosti in naknadna obdelava cevi

Kristalinični polimeri na osnovi poliolefina se razlikujejo glede na velikost in zmogljivost cevnega izdelka, ko je dobavljen. Glavni razlogi so, prvič, postopek hlajenja taline iz poliolefina, da pride do kristalizacije, kristalnosti in kristalne oblike ter temperature in temperature, čas do postavitve. Drugič, temperatura tik ob cevi je običajno višja od sobne temperature. Tretjič, tik ob montažni liniji napetosti v cevi. Da bi dosegli stabilnost zmogljivosti in velikosti, je treba cevi PPR postaviti splošno polietilensko cev za 24 ur s tekoče trakove, polipropilensko cev pa po 48 urah, v skladu z ustreznimi standardi za preskušanje zmogljivosti.