Previdnost pri uporabi stroja za ekstrudiranje PVC cevi

Correct and reasonable use of PVC pipe extruder machine can give full play to the machine’s efficiency, maintain good working conditions, and extend the machine’s service life.

The use of PVC pipe extruder machine includes a series of links such as machine installation, adjustment, test run, operation, maintenance and repair. Its use has the typical characteristics of general machines, mainly in drive motor and speed reducer.

However, the working system of the PVC pipe extruder machine is the extrusion system, but it has unique characteristics, so special attention should be paid when using the screw extruder.

The installation, adjustment, and test run of the machine are generally clearly stipulated in the operating instructions of the extruder. Here is a brief description of the operation method, maintenance and maintenance of the extruder as follows:

The operation method of PVC pipe extruder machine

Operators must be familiar with the extruder’s structural characteristics, especially to correctly grasp the structural characteristics of the screw, heating and cooling control instrument characteristics, head characteristics and assembly conditions, etc., to correctly grasp the extrusion process conditions. 

The operating methods of extruding different plastic products are different, but there are also similarities. The following briefly introduces the same operation steps and matters that should be paid attention to when extruding various products.

1. Preparation Before Driving

1. Plastics used for extrusion moulding. The raw materials should meet the required drying requirements. If necessary, further drying is required, and the raw materials should sieve to remove agglomerates and mechanical impurities.
2. Check whether the water, electricity, and gas systems in the equipment are normal to ensure that the water and gas paths are unblocked and leak-free, whether the electrical system is standard, whether the heating system, temperature control, and various instruments are working reliably; low-speed test of the auxiliary machine empty car Operate and observe whether the equipment is operating normally; start the vacuum pump of the sizing table to observe whether it usually works; add oil to lubricate the lubricated parts of various equipment. If any fault is found, remove it in time.
3. Install the machine head and sizing sleeve. According to the variety and size of the product, select the specifications of the machine head. Install the machine head in the following order.
   • The machine head should be assembled and installed on the extruder as a whole.
   • Before assembling the machine head, wipe off the grease applied during storage, carefully check the surface of the cavity for bruises, scratches, and rust spots, perform necessary polishing, and then apply a layer of silicone oil on the surface of the runner.
   • Assemble the plates of the machine head in order, apply high-temperature grease to the threads of the bolts, and then tighten the bolts and flanges.
   • Place the perforated plate between the flanges of the machine head to ensure that the perforated plate is pressed tightly without overflow.
   • Adjust the horizontal position of the die before tightening the fastening bolts of the connecting flange between the die head and the extruder. The square die head can adjust horizontally, and the round die head should be based on the bottom surface of the finalized model. The bottom surface of the mould is leveled.
   • Tighten the connecting flange bolts, tighten the machine head fastening bolts, install the heating ring and thermocouple, pay attention to the heating ring to be close to the outer surface of the machine head.
   • Install the sizing sleeve and adjust it in place, check whether the centerline of the main engine, the sizing sleeve and the tractor are aligned. After adjustment, tighten the fixing bolts. Connect the water pipes and vacuum tubes of the sizing sleeve.
   • Turn on the heating power supply to evenly heat the machine head and cylinder. At the same time, open the cooling water at the bottom of the hopper and the gearbox and the water inlet valve of the exhaust vacuum pump. When heating, the temperature of each section is first adjusted to 140°C, and when the temperature rises to 140°C, the temperature is kept for 30-40min. Then the temperature is raised to the temperature during average production. When the temperature rises to the temperature required for regular production, please keep it for about 10 minutes to stabilize each part of the machine before it can start production. The length of the heat preservation time varies according to different extruders and types of plastic raw materials. Keep the temperature for some time to keep the temperature inside and outside the machine consistent to prevent the meter from indicating that the temperature has reached the required temperature, but the actual temperature is too low. At this time, if the material is put into the extruder, the actual temperature is too low, and the melt viscosity of the material is too high. Causes axial force overload and damages the machine.
   • Feed the raw materials used for driving into the hopper for use.

2. Drive

1. You can start driving after the constant temperature. Before driving, tighten the head and the flange bolts of the extruder again to eliminate the difference in thermal expansion between the bolts and the head. The order of tightening the head bolts is to tighten diagonally. Evenly. When tightening the flange nuts of the machine head, the tightness of all sides must be consistent. Otherwise, the material will run out.
2. When driving, select and press the “Ready to Start” button, then connect the “Start” button, then slowly rotate the screw speed adjustment knob. The screw speed starts slowly. Then gradually speed up while adding a small amount of material. Pay close attention to the indication changes of the host ammeter and various indicator heads when feeding. The screw torque cannot exceed the red mark (generally 65%-75% of the torque meter). Before the plastic profile is extruded, no one can stand directly in front of the die to prevent injury accidents caused by bolts breaking or due to damp and foaming raw materials. After the plastic is extruded from the die of the machine head, the extrudate needs to be slowly cooled and led to the traction device and the shaping die, and these devices are activated. Then according to the indicated value of the control instrument and the requirements for extruded products. Adjust each part accordingly to make the entire extrusion operation reach a normal state. And add enough material as needed. The twin-screw extruder uses a metering feeder to feed evenly and at a constant rate.
3. When the die is evenly discharged, and the plastic is suitable, it can pull into the shaping sleeve. Judgment of the degree of plasticization requires experience. Generally, it can judge according to the appearance of the extruded material. That is, the surface is glossy, free of impurities, no foaming, burnt material, and discoloration, and the extruded material is squeezed by hand to a certain extent and does not appear. Burrs and cracks have a certain degree of elasticity, which means that the material is plasticized well. If the plasticization lacks, the screw speed, barrel, and head temperature can adjust appropriately until the requirements are met.
4. During the production process of the PVC pipe extruder machine, check whether the various process parameters are expected according to the process requirements and fill in the process record sheet. According to the quality inspection standards, check the quality of the profile products and take timely solutions when problems are found.

3. Parkiranje

1. Stop feeding and squeeze out the plastic in the PVC pipe extruder machine. When the screw is exposed, turn off the power of the barrel and head, and stop heating.
2. Izklopite napajanje ekstruderja in pomožnih strojev ter ustavite vijak in pomožne stroje.
3. Odprite priključni flanšo glave stroja in razstavite glavo stroja. Očistite perforirano ploščo in različne dele glave stroja. Da bi preprečili poškodbe notranje površine glave stroja med čiščenjem, je treba ostanek materiala v glavi stroja očistiti s jeklenimi zaključki in jeklenimi listi. Nato je treba plastiko, ki se oprijema glave stroja, odstraniti z brusnim papirjem, spolirati in prevleči z motornim oljem ali silikonskim oljem. 
4. Čiščenje vijaka in cevi. Po odstranitvi glave ponovno zagnite glavni motor, dodajte parkirni material (ali drobljeni material) in očistite vijak in cavo. V tem času naj bo vijak na nizki hitrosti (približno obr/min), da zmanjšate obrabo. Ko se ustavljeni material zdrobi v prah in ga popolnoma iztisne, lahko uporabite stisnjen zrak, da večkrat izpihnete preostale pelete in prah iz dovodnega in izpušnega portala, dokler ni več ostankov v cevi, nato zmanjšajte hitrost vijaka na nič in ustavite iztiskanje. Izklopite glavno napajanje in glavni ventil hladne vode.
5. Varnostne ukrepe, na katere je treba biti pozoren pri ekstrudiranju, so elektrika, toplota, mehansko vrtenje ter nalaganje in razlaganje težkih delov. Delavnica za ekstruder mora biti opremljena z dvigalnim orodjem, sestavljanjem in razstavljanjem glave, vijaka in drugih težkih delov, da se zagotovi varna proizvodnja.

Vzdrževanje in servis stroja za ekstrudiranje PVC cevi

Sistem za ekstrudiranje vijaka vzdržujemo na dva načina: dnevno vzdrževanje in redno vzdrževanje.

1. Dnevno vzdrževanje je rutinsko delo, ki ne porablja ur delovanja opreme in se običajno opravi med zagonom. Poudarek je na čiščenju stroja, mazanju gibljivih delov, privijanju navojnih delov, ki se lahko razrahljajo, pregledu in nastavitvi motorjev, kontrolnih instrumentov, različnih delov in cevovodov.
2. Redno vzdrževanje se običajno izvaja po 2500–5000 urah neprekinjenega delovanja ekstruderja, ko je stroj ugasnjen. Stroj je treba razstaviti za pregled, merjenje in identifikacijo obrabe glavnih delov, zamenjavo delov, ki so dosegli določeno mejo obrabe, in popravilo poškodovanih delov.
3. Ni dovoljeno delovati prazno, da se izognete valjanju vijaka in stroja.
4. Če se med delovanjem ekstruderja pojavi nenormalno šumenje, ga je treba nemudoma ustaviti za pregled ali popravilo.
5. Strogo preprečite, da bi kovine ali drugi odpadki padli v zalivnik, da bi se izognili poškodbam vijaka in cevi. Da bi preprečili, da bi železni odpadki vstopili v cavo, lahko na vhodu materiala v cavo namestite magnetni absorbcijski komponent ali magnetno okvirje, da preprečite, da bi odpadki padli v cavo. Material mora biti predhodno prečiščen.
6. Pozorni bodite na čisto proizvodno okolje in ne mešajte smeti in nečistoče v material, da ne blokirata filtrirne plošče, kar vpliva na izhod in kakovost izdelka ter poveča upor glave stroja.
7. Ko je treba ekstruder dolgo časa ugasniti, ga je treba premazati z antikorozijskim, mazalnim maščobnim sredstvom na delovno površino vijaka, osi stroja in glave. Majhen vijak je treba obesiti v zraku ali postaviti v posebno leseno škatlo in poravnati z lesenimi bloki, da se izognete deformaciji ali udarcem vijaka.
8. Redno kalibrirajte temperaturni kontrolni instrument, da preverite pravilnost njegove nastavitve in občutljivost kontrole.
9. Vzdrževanje reduktorja ekstruderja je enako kot pri splošnem standardnem reduktorju. Predvsem preverite obrabo in okvaro zobnikov in ležajev. Mehanski sklop naj uporablja mazalno olje, navedeno v priročniku stroja, in dodajte olje glede na določeno raven olja. Če je olja premalo, se mazanje ne bo obrnilo in bo življenjska doba delov zmanjšala; če je olja preveč, se bo izrazito segrevalo, poraba energije bo visoka, olje se bo hitro poslabšalo in bo mazanje neučinkovito ter povzročilo poškodbe delov. Tesnilna garnitura (obroč) naj zamenja del, ki pušča olje iz redukcijskega sklopa, da se zagotovi prava količina mazalnega olja.
10. Notranja stena cevi za hlajenje, ki je pripeta na ekstruder, je nagnjena k nastajanju vodnega kamna, zunanjost pa je nagnjena k koroziji in rji. Pri vzdrževanju je treba pazljivo preveriti. Prevelik vodni kamen bo blokiral cev in ne bo dosegel hlajenja. Če je rja močna, bo prišlo do uhajanja vode. Zato je treba pri vzdrževanju uporabiti ukrepe za odstranjevanje vodnega kamna in protikorozivno hlajenje.
11. Pri DC motorju, ki poganja vijak, je bistveno preveriti obrabo in stik krtač. Prav tako je treba pogosto meriti, ali je upornost izolacije motorja nad določeno vrednostjo. Poleg tega preverite, ali so povezovalni žici in drugi deli zarjaveli, in sprejmite zaščitne ukrepe.
12. Določite osebo, odgovorno za vzdrževanje opreme, in vključite podrobne zapise o vsaki situaciji vzdrževanja in popravila v datoteko upravljanja opreme v tovarni.