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Panalungtikan ngeunaan Pangaruh Kecepatan Rotasi Screw Mesin Molding Injeksi dina Kamampuhan Plasticizing sareng Viskositas Semu

Pébruari 23, 2023

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Mesin suntik molding mangrupikeun alat utama pikeun molding plastik, utamana ku sistem suntik.Sistem, sistem clamping, sistem kontrol listrik, sistem lubrication, Sistim transmisi hidrostatik,Sistim pemanasan sarta cooling, Sistim ngawaskeun kaamanan, jsb. Pikeun ngaronjatkeun kualitas produk, efisiensi produksi, ngurangan konsumsi énergi, jalma geus dipigawé panalungtikan di-jero on it.The panalungtikan dina mesin suntik molding nyaeta multifaceted, kaasup sistem kontrol listrik.Transformasi calakan.Transformasi Servo tina sistem transmisi Hemat énergi pemanasan sarta cooling systemReform.The screw transformasi struktur kamampuh plasticizing. Screw mangrupikeun inti tina komponén mesin cetak suntikan, anu parameter nangtukeun volume suntik mesin suntik, peneliti geus studyMore. The hadé éta plasticizing uniformity of screw nu ngagambarkeun akurasi pengulangan produk.The luhur akurasi pangukuran, parameter kinerja plasticizing uniformity nyaeta katempo viskositas.Wherein modifikasi struktur screw mantuan pikeun ngurangan viskositas katempo tina ngalembereh., screw éta.

Kapasitas ditangtukeun ku struktur screw jeung speed screw, tekanan, laju, suhu, etc.It teh parameter utama pikeun ngukur kinerja screw nu. Wang XishMelting of suntik screwBody angkutan ieu dianalisis téoritis. Li Zhenget The effects of temperature and back pressure on snailInfluence of rod plasticizing ability. Kapasitas plasticizing ngagambarkeun efisiensi produksi mesin injection molding,Perlu ningkatkeun kamampuan plasticizing screw pikeun kauntungan ékonomi perusahaan.

Kamampuh plasticizing tina rod nujul kana kualitas bahan plasticized per Unit waktos screw.The mesin suntik molding kualitas gudang bahan ditangtukeun ku chamber Pangukuran., jeung kaluar tina screw homogénisasi sectionConnected jeung kamar ukur, volume di outlet tina screw bagian homogenizing bisa diukur. Kamampuh plasticizing of screw ieu ditangtukeun ku laju pass.Dina seleksi bahan., viskositasna dipangaruhan pisan ku laju geser sareng suhu darajat sensitipitas rendah polipropilén pikeun ngagampangkeun deteksi sareng observasi hasil ékspérimén.. Ieu paperThe widang aliran PP ngalembereh dina bagian homogenizing of screw nu dianalisis ku software Fluent.

Ngagunakeun métode panalungtikan ngagabungkeun ékspérimén jeung analisis téoritis, rotasi screw

Balukar tina jero screw béda dina suhu, viskositas semu, Laju sareng kamampuan plasticizingLaju pass volumetrik di outlet bagian homogenizing screw dianalisis pikeun ngaoptimalkeun speed Screw parameter prosés produksi mesin injection molding..

 

1 Analisis TéoritisDina tulisan ieu, homogenization of LYH680 palastik mesin suntik molding ieu simulated ku Fluent.Section cairan pipe, nyetel speed screw béda, analisa bagian homogenisasi pipaLaju transit volumetrik di outlet bagian homogenisasi cairan propiléna dimeunangkeun.. Fase mesin suntik moldingThe parameter relevan nyaéta: panjang bagian homogenized of screw nyaeta 80 mm, jeung suhu laras dina bagian homogenizing diaturSet di 220 C, tekanan lebur dina bagian homogenizing nyaeta 1.5 MPa, jeung jero alur screw nyaeta 2.2Mm, screw screw sudut nyaeta 17.66 °, screw panjang-diaméter ratio nyaeta 19.6, screw diaméterna 32 mm; Kapadetan lebur polipropilén (PP) éta 770 kg / m3 Titik lebur nyaéta 170 °C, koefisien konduktivitas termal tina ngalembereh nyaeta 0,182W / (m · °C), jeung rasio ngalembereh Kapasitas panas tina 2900 J / (kg · C), ngalembereh viskositas tina 421 Pa · s (453 K / 320)Pa·s(463 K)/250 Pa·s(473 K)。 Dina rékayasa praktis, Pertimbangkeun dénsitas fluida robah saeutik alatan kanyataan yén polimér molten ieu sheared dina mesin suntik molding nalika premolded. Laju geser kirang ti 10-3 m / s, dina waktu nu ngalembereh lokasina di wewengkon rheological non-Newtonian kahiji Di wewengkon ieu, polimér ngalembereh bisa dianggap salaku cairan Newtonian, jadi lebur PP dianggap salaku hiji cairan Newton laminar incompressible dina analisis tés téoritis jeung eksperimen..

  • Ngadegkeun sistem koordinat

Saluran puteran asli anu dilalui ku bahan dipanjangkeun kana saluran kuboid,Modél spasi tilu diménsi diwangun ti asal ditémbongkeun dina Gambar 1 ka Gambar 3.

1.2 Ngadegkeun Persamaan Pangaturan Cairan (Phi) + div (p f) = div (gradpi) + S. (1) Dimana φ mangrupakeun variabel fisik umum; Koéfisién difusi umum pakait jeung phi; S nyaéta istilah sumber umum.

Nurutkeun kana métode Guangyi, persamaan konservasi massa jeung moméntum ditetepkeun dina lawang bagian homogenisasi tina pesawat xy (z = 0).

dV

r

Z = – tina Pb + Ï€ F + d V.

(2) Dina rumus dt: rho nyaéta dénsitas lebur, kg / m3; Vz nyaéta laju aliran dina arah z, m / s, ngasupkeun alur spiral di wewengkon homogenization; F nyaéta akselerasi gravitasi, m / s2; Pb nyaéta tekanan balik, Pa; Nyaéta viskositas ngalembereh,

Pa·s; T pikeun waktos, s; ▽ nyaéta Hamiltonian,▽= ∂ i+ ∂ j+ ∂ k。 ∂x ∂y ∂z

Persamaan (2) nyaéta persamaan kasatimbangan moméntum (persamaan N-S) tina cairan kentel, cairan dina alur spiral dianggap salaku aliran isothermal; Widang viskositas sareng dénsitas seragam. Lebar alur spiral jauh leuwih badag batan jero alur spiral, jeung pangaruh témbok samping screw teu dipaliré. Ngalembereh ngalir pinuh sapanjang saluran screw, ignoring pangaruh aliran tina inlet na outlet, tapi tempo efek tina tekanan balik sabalikna. Persamaan N-S disederhanakeun ku kaayaan di luhur:

2

dp

dy=1·b。 (3) dy2eta dx

Ngahijikeun y dua kali sarta méré kaayaan wates (y = 0, Vz = 0; Y = h, Vz = π NDcos theta / 60). Fungsi kaayaan distribusi laju aliran dina arah lebur dicandak, éta

NDyπ cos theta hy-y2pb

Vz = 120 jam – 2jeung × Lsintheta. (4)

Dimana h nyaéta jero alur screw dina bagian homogenization, m; Sudut helix of screw nu, (°); L nyaéta panjang ruas homogenized, m; N nyaéta speed screw, r a d / abdi n; D nyaéta diaméter lempeng tina rod screw, m.

1.3 Itungan kapasitas plasticizing teoritis

Ngaganti Eq. (4) kana persamaan harti aliran, Q = WhVz = π DhVzsintésis, méré

22 32

Mpt = QÏ€ = Ï€ D NhÑ€sin θ cos θ – p Dsin

Pitch. (5) 120 12 L dimana: W nyaéta lebar bagian cairan, m; MPT nyaéta Plastik Téoritis tina Screw Type Plastik Injection Molding Machine

Kapasitas kimiawi, kg / s; Q nyaéta laju lulus volume bagian homogénisasi lebur, m3 / s. Ngaliwatan persamaan (5), eta bisa ditempo yén kamampuh plasticizing of screw nu kapangaruhan ku rupa-rupa parameter prosés kayaning diaméter screw, sudut alur screw, tekanan ngalembereh tur jero alur screw. Nu leuwih luhur speed screw, leuwih kuat kamampuh plasticizing; Nalika viskositas semu ngalembereh nambahan, kamampuh plasticizing of screw naek.

Hasil ékspérimén jeung analisis simulasi

2.1 Analisis simulasi jeung hasil

1) Kaayaan pikeun analisis simulasi.

Beungeut tungtung inlet: ti fungsi kaayaan distribusi laju dina arah z tina ngalembereh (sapertos (4)), laju dina inlet sahiji bagian homogenizing robah kalawan nilai y. Ayeuna N = 120, 140, 160, 180 rad / mnt digantikeun kana Vz masing-masing, jeung laju simulasi awal sapanjang arah spiral di lawang tina bagian homogenization ditangtukeun ngaliwatan harti fungsi Fluent kalawan basa programming sorangan UDF., éta, laju awal dina kaayaan simulasi jeung diukur; Kusabab tekanan lebur dina inlet jauh leuwih handap tina tekanan sirah screw, tekanan dina inlet sahiji bagian homogenization nyaeta 0; Nurutkeun kana parameter prosés bahan PP jeung alat, éta

Suhu ngalembereh disetel ka 465 K. Tembok sisi kénca jeung katuhu: pesawat y-z (x = 0), (x sarua 3.2 × 10-2 m) salaku bagian homogenisasi

Dua sisi témbok alur screw diatur salaku témbok non-dieunakeun, sarta suhu ngalembereh nyaeta suhu screw, nu disetel ka 473 K nurutkeun ciri bahan PP jeung kaayaan sabenerna pakakas.

Luhur jeung handap sidewalls: pesawat x-z (y = 0), (y = 2.2 × 10-3 m) salaku sisi handap jeung luhur alur screw sahiji bagian homogenization, sisi handap dianggap salaku témbok non-slip, suhu ngalembereh nyaeta suhu screw, sareng suhu disetel ka 473 K nurutkeun ciri bahan PP jeung kaayaan sabenerna pakakas; Sisi luhur alur screw dina bagian homogenization nyaéta beungeut kontak tina ngalembereh jeung tong, laju aliran ngalembereh nyaeta maksimum, sarta suhu ngalembereh sarua jeung suhu pamanas tong, nu disetel ka 493 K nurutkeun kaayaan produksi bahan PP.

Beungeut tungtung outlet: pesawat x-y (z = 0.264 m) salaku outlet tina bagian homogenization, wates outlet tekanan diadopsi, dimana tekananna sabalikna arah z, sarta tekanan disetel ka cocog parabot ékspérimén pikeun analisis gampang tur babandingan, jeung tekanan deui disetel ka -1.2 MPa.

  • Hasil analisis simulasi

Pikeun x = 0.01, diagram kurva laju, hawa sarta viskositas di kaluar tina bagian homogenization salaku fungsi tina jero alur spiral ditémbongkeun dina Gambar. 4 ka 6.

Urang tiasa ningali tina Gambar 4 yén kalawan kanaékan speed screw, laju bagian homogénisasi di jalan kaluar ogé ngaronjat, kalawan kanaékan jero alur screw, laju mimiti ngurangan lajeng naek, nu alatan gaya geser jeung viskositas dina surfaces luhur jeung handap alur screw, saluyu jeung cairan polimér dina piring.

Parobahan antara. Sakumaha urang tiasa tingali tina Gambar 4, kalawan kanaékan speed screw, Laju di outlet bagian homogenizing ogé ngaronjat. Kalawan ngaronjatna jero alur, laju nurun heula lajeng naek. Ieu alatan gaya geser badag sarta viskositas on surfaces luhur jeung handap alur, nu konsisten jeung parobahan cairan polimér antara pelat. Parobahan suhu dina arah radial ditémbongkeun saperti dina Gbr. 5. PP ngalembereh aya dina kontak jeung screw di handap (y = 0), luhureun kontak jeung screw nu (y = 0,0022m) konduksi panas lumangsung, panas ti handap, luhur kana lebur, hawa ti dua sisi ka arah handap trend, ngabentuk kurva suhu cekung. Jeung kanaékan speed screw, laju nambahan, waktos pemanasan dina runner nurun, and the temperature decreases with the increase of the number of revolutions. As shown in FIG. 6, the apparent viscosity of the melt first increases and then decreases with the increase of the spiral height, Contrary to the temperature curve, the apparent viscosity is the lowest at the top of the highest melt temperature, and the apparent viscosity is the highest at the middle of the lowest melt temperature. Jeung kanaékan speed screw, the apparent viscosity of the melt is higher and higher, and the apparent viscosity uniformity decreases. It can be seen that the apparent viscosity of PP melt is inversely proportional to temperature, which shows the accuracy of simulation.

It can be seen from Figure 6 that the viscosity is not fixed in the Fluent simulation, so we take the average viscosity at the exit of the homogenization section at x = 0.01 here, because the viscosity changes here through the data comparison.

The viscosity that is closest to the theoretical calculation.

2.2 Measurement and Analysis of Plasticizing capacity

After preheating the injection molding machine, the polypropylene raw material is put into the funnel for plasticity. The rotating speed parameters of the screw are set at 120,140,160,180 r/min, the temperature of the homogenized section is set at 220 °C, and the melt pressure in the homogenizing section is set at 1.2 MPa. The storage time t at each rotating speed is recorded with a stopwatch, and then the empty feed is set.

After injection, after the injection is cooled, the mass m of the injection is collected and measured, and the actual plasticizing ability mps is obtained by mps = 1000m/t. The comparison results with the theoretical plasticizing ability mpt under the same conditions are shown in Fig. 7.

Figure 7 shows that the theoretical plasticizing capacity and screw speed of the screw approximate a function

Jeung kanaékan speed screw, the plasticizing ability of screw is enhanced, and the actual screw screw

Rod plasticizing ability is lower than the theoretical plasticizing ability, the actual plasticizing ability of the injection molding machine at the speed of 120 ~ 180 rad / min accounts for 82% ~ 86% of the theoretical plasticizing ability, indicating that the injection molding machine screw plasticizing ability is above the average level. 2.3 Error analysis

There are differences between the actual plasticizing ability and the theoretical plasticizing ability of the screw, nothing more than these points: 1) part of the material forms a molten film during the plasticizing process, resulting in the leakage of the material; 2) The leakage of spiral pressure was not considered in the theoretical plasticizing ability analysis, which caused some materials to stay on the spiral edge. 3) In addition to the heat transmitted by the barrel heater, the material is more from the shear heat of the screw and the friction between the materials, resulting in the thermal decomposition of part of the material.

Jeung kanaékan speed screw, the actual plasticizing ability is slowing down, there are the following points: 1) Jeung kanaékan speed screw, the shear heat of the screw is increasing, resulting in the thermal decomposition of part of the material; 2) The increase in temperature reduces the viscosity of the material, increases the reverse pressure, hinders the progress of the material, and causes the actual plasticizing energy to slow down.

Conclusion With the increase of screw groove depth, the uniformity of temperature and apparent viscosity decreased, and the plasticizing ability increased, but the precision of product quality decreased. The plasticizing ability increased with the screw speed increasing, but the uniformity of temperature and apparent viscosity decreased with the increase of screw speed. Ngaronjatkeun suhu screw ngabantosan ngamajukeun keseragaman viskositas anu katingali sareng ningkatkeun akurasi kualitas produk.; Pikeun mastikeun kualitas produk sareng ningkatkeun efisiensi produksi, jerona, suhu sarta speed screw kudu dioptimalkeun.

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