Chii chiri musimboti, maitiro, kushandiswa uye maitiro ekuumba jekiseni nemuchina wekuumba jekiseni?

Nhasi ngatitaure pamusoro pemusimboti, maitiro, kushandiswa uye maitiro ekuumba jekiseni kubudikidza jekiseni kuumba muchina.

1. Nheyo ye jekiseni kuumbwa. Wedzera granular kana purasitiki yehupfu muhopi yemuchina wejekiseni. Plastiki inodziya uye inonyungudutswa mumushini wejekiseni kuti irambe ichiyerera, wobva waiswa jekiseni muforoma yakavharika pasi pekumanikidzwa kwakati. Mushure mekutonhora uye kuumba, inonyunguduka Purasitiki inosimbiswa kuti ive chikamu chepurasitiki chinodiwa. To

2. Hunhu yekuumba jekiseni
Jekiseni molding ine pfupi kugadzirwa kutenderera uye yakakwirira goho. Jekiseni molding inogona kugadzira zvikamu zvepurasitiki zvine maumbirwo akaoma, yakakwirira saizi zvinodiwa uye akasiyana anoisa, izvo zvakaoma kuwana nedzimwe nzira dzekugadzira mapurasitiki; chechipiri, jekiseni molding iri mukugadzira maitiro Zviri nyore kuziva otomatiki, zvakadai sejekiseni, demolding, kubviswa kwegedhi uye mamwe mabasa anogona kuve otomatiki, saka jekiseni molding yave kushandiswa zvakanyanya.

2.1 Zvakanakira:
The molding cycle ipfupi, kubudirira kwekugadzira kwakakwirira, uye zviri nyore kuziva otomatiki. Inogona kuumba zvimiro zvakaoma, zviyero zvakarurama, zvikamu zvepurasitiki nesimbi kana kwete-simbi inopinza, yakagadzikana chigadzirwa chemhando, uye yakakura application range.

2.2 Zvakaipa:
Mutengo wemichina yekuumba jekiseni wakakwira zvakanyanya; chimiro chejekiseni molds chakaoma; mutengo wekugadzira wakakwira, kutenderera kwekugadzira kwakareba, uye haina kukodzera kugadzirwa kwechikamu chimwe chete uye madiki-batch epurasitiki zvikamu.
3. Kushandisa Kunze kweashoma thermoplastics (fluoroplastics), dzinenge dzese thermoplastics dzinogona kushandiswa kugadzira zvikamu zvepurasitiki nekuumba jekiseni. Jekiseni molding haingoshandiswi chete kuumbwa kwe thermoplastics, asi zvakare yakashandiswa zvakabudirira kuumba thermoset mapurasitiki. Nekuti iyo IC tray ine huremu huremu, zvigadzirwa zvaro zvakaumbwa zvinoverengera 20-30% yezvese zvazvino zvigadzirwa zvepurasitiki. Kuti uwedzere kuwedzera huwandu hwemajekiseni akaumbwa epurasitiki zvikamu, mamwe matekinoroji ejekiseni akagadzirwa akanyatso kuumba zvikamu zvepurasitiki zvine zvivakwa zvakakosha kana zvakakosha zvimiro.. Zvakadai sejekiseni rakanyatsojeka rezvikamu zvepurasitiki zvepamusoro-soro, jekiseni rine mavara akawanda emusanganiswa mavara epurasitiki zvikamu, sandwich jekiseni resandwich plastiki zvikamu zvinoumbwa nezvinhu zvakasiyana mukati nekunze, uye jekiseni compression molding ye optically transparent plastic parts. To

4. Injection molding process

4.1 Kugadzirira kusati kwaumbwa

Raw material yekutariswa kwekutarisa uye process performance kuyerwa: kusanganisira kuongororwa kwemavara epurasitiki, particle size uye kufanana, fluidity (melt index, viscosity), kugadzikana kwekushisa uye shrinkage rate. To

Plastiki preheating uye kuomesa: bvisa hunyoro hwakawandisa uye kuvhuvhuta mune izvo zvinhu kudzivirira kuremara kana kushatisa pamusoro pechikamu chepurasitiki mushure mekuumbwa., izvo zvichakanganisa kutaridzika uye kunaka kwemukati chikamu chepurasitiki. Material drying nzira: kugadzirwa kwebatch diki, kushandisa oven drying; kugadzirwa kwakawanda, kushandisa kufashaira kuomesa kana vacuum kuomesa.
Kuchenesa mbiru: Iyo dhiramu inoda kucheneswa kana uchichinja zvigadzirwa, kuchinja zvinhu uye mavara. To

Isa preheating: kuderedza kusiyana kwekushisa pakati pezvinhu uye kuisa, kuderedza shrinkage stress yepurasitiki yakapoteredza kuisa, uye chengetedza kunaka kwepurasitiki. To

Kusarudzwa kwemumiririri wekusunungura: Inowanzo shandiswa kuburitsa midziyo inosanganisira zinc stearate, parafini yemvura uye silicone mafuta. To

4.2 Injection process

Kudyisa: Wedzera granular kana purasitiki yehupfu muhopi yemuchina wejekiseni. To

Plasticization: Kuburikidza nekudziya kwemudziyo wekudziya wemushini wejekiseni, iyo yepurasitiki mbishi zvinhu mu screw inonyungudutswa uye inova purasitiki inonyungudika ine yakanaka plastiki. To

Kuzadza mold: Iyo yepurasitiki yakanyunguduka inosundirwa neplunger kana screw yemuchina wejekiseni kuti ipinde uye kuzadza iyo mold cavity kuburikidza nenozzle uye yekudurura system ye mold pane imwe dzvinyiriro nekumhanya.. To

Kudzvinyirirwa kuchengetedza uye kudya: mushure mekunyunguduka kwazadza mhango, pasi peplunger kana screw yemushini wejekiseni, iyo yakanyunguduka ichiri kuchengetedza kumanikidzwa kwekudya, kuitira kuti kunyunguduka mubhodhoro kurambe kuchipinda mugomba kuti riwedzere purasitiki mugomba Shrinkage inodiwa uye inogona kudzivirira kunyungudika kuyerera kumashure..
Kutonhodza mushure mekunge gedhi raoma nechando: Pashure penguva yakati, purasitiki yakanyungudutswa mugomba inosimbiswa kuita yakasimba kuti ive nechokwadi chekuti chikamu chepurasitiki chine kusimba kwakakwana kana chaumbwa uye hachikonzeri warpage kana deformation.. To

Demoulding: Chikamu chepurasitiki chinotonhodzwa kune imwe tembiricha, uye iyo ejection mechanism inosundira chikamu chepurasitiki kubva muforoma. To

4.3 Post-kugadziriswa kwezvikamu zvepurasitiki

Zvikonzero uye mhedzisiro yepost-processing:
Nekuda kwepurasitiki isina kuenzana kana kusaenzana crystallization, kutaridzika uye kutonhora kwepurasitiki mumhango; kana nekuda kwesimba rekuisa simbi kana kusarongeka kwechipiri kugadzirisa kwezvikamu zvepurasitiki, kumwe kushushikana kwemukati kunowanikwa muzvikamu zvepurasitiki , Zvinokonzera deformation kana kuputika kwezvikamu zvepurasitiki panguva yekushandiswa, saka tinofanira kuedza kuvabvisa. To

Annealing kurapwa: a heat treatment process in which plastic parts are placed in a constant temperature heating liquid medium (such as hot water, hot oil, liquid paraffin, Nekuti iyo IC tray ine huremu huremu) or hot air circulation oven for a period of time, and then slowly cooled to room temperature.
a) Tembiricha: 10°~15° higher than the operating temperature or 10°~20° lower than the heat distortion temperature.
b) Time: Kazhinji, it can be calculated at about half an hour per millimeter related to the type of plastic and the thickness of the plastic part. To
c) Function: Eliminate the internal stress of the plastic part, stabilize the size of the plastic part, increase the crystallinity, stabilize the crystalline structure, thereby improving its elastic modulus and hardness.Humidity conditioning treatment: a post-treatment method that puts the newly demolded plastic parts into a heating medium (such as boiling water, potassium acetate solution) to speed up the moisture absorption balance. (Mainly used for plastics that are highly hygroscopic and easily oxidized, such as PA)

a) Tembiricha: 100~121℃ (the upper limit is taken when the heat distortion temperature is high, and the lower limit is taken vice versa).
b) Time: The holding time is related to the thickness of the plastic part, usually 2~9h. To
c) Chinangwa: Eliminate residual stress; make the product reach moisture absorption balance as soon as possible to prevent dimensional changes during use. To

5. Process parameters of injection molding

5.1 Tembiricha

a) Barrel temperature

The barrel temperature should be between the viscous flow temperature (or melting point) and the thermal decomposition temperature. The temperature of the plunger barrel is 10-20°C higher than the temperature of the screw barrel. To

Plastic characteristics: heat-sensitive plastics such as polyoxymethylene, polyvinyl fluoride, nezvimwewo. must strictly control the maximum temperature of the barrel and the residence time in the barrel; the thermoplastic plastic with glass fiber should increase the barrel temperature due to poor fluidity. In order to prevent the melt from being hardened early in the barrel, the temperature of the barrel tends to take a small value.
Plastic parts and mold structure: For thin-walled parts, the barrel temperature is higher than thick-walled parts; for parts with complex shapes or with inserts, the barrel temperature should also be higher. To

The temperature distribution of the barrel generally follows the principle of high front and low back, ndizvo, the temperature of the rear section of the barrel (feeding port) is the lowest and the nozzle temperature is the highest.

For the screw injection machine, in order to prevent thermal degradation of the plastic due to the shear friction heat between the screw and the melt, the melt and the melt, and the melt and the barrel, the temperature of the front section of the barrel can be slightly lower than the middle section. To judge whether the temperature of the barrel is appropriate, the air injection method can be used to observe or directly observe the quality of the plastic parts.

During air injection, if the material flow is uniform, smooth, bubble-free, and uniform in color, the material temperature is appropriate; if the material flow is rough, silver wire or discoloration, it means that the material temperature is inappropriate. To

b) Nozzle tembiricha

Kazhinji, it is slightly lower than the maximum temperature of the barrel to prevent the molten material from drooling at the nozzle. But it should not be too low, otherwise the melt will have premature solidification at the nozzle and block the nozzle, or premature solidification will be injected into the mold cavity and affect the quality of the plastic parts. To

c) Munyaya yekugutsa mold kuzadza

The mold temperature is determined by the characteristics of the plastic, the size and structure of the plastic part, performance requirements and other process conditions. Mold temperature ↑, fluidity ↑, density and crystallinity ↑, shrinkage rate and productivity ↓.
The mold temperature is usually controlled by a constant temperature cooling medium; there is also a way to maintain a certain temperature by injecting the molten material into the mold to achieve a balance between natural heating and natural heat dissipation; in special cases, resistance wires and resistance heating rods can also be used to maintain a certain temperature. The mold is heated to keep the mold at a constant temperature. But no matter what, for the plastic melt, it is a cooling process. To

5.2 Pressure

(1) Plasticizing pressure (back pressure): refers to the pressure of the melt on the top of the screw when the screw retreats when the screw injection machine is used. To

The plasticizing pressure increases, the temperature of the melt and its uniformity are improved, the color materials are mixed uniformly, and the gas in the melt is discharged. But the plasticization rate is reduced, and the molding cycle is prolonged. To

In general operation, under the premise of ensuring the quality of plastic parts, the plasticizing pressure should be as low as possible, generally about 6MPa, and usually rarely more than 20MPa
To
(2) Jekiseni pressure: refers to the pressure exerted by the plunger or the top of the screw on the plastic melt. To

Function: Overcome the flow resistance of the melt flow during the filling process during injection, so that the melt has a certain filling rate; when the pressure is maintained, the melt is compacted and prevented from flowing backward. To

Size: It depends on the type of injection machine, the type of plastic, the mold structure, the mold temperature, the wall thickness of the plastic part, and the structure and size of the pouring system. Under normal circumstances: injection pressure of high-viscosity plastic> low-viscosity plastic; high injection pressure for thin-walled, large-area, and complex-shaped plastic parts; simple mold structure, larger gate size, and lower injection pressure; plunger injection machine Injection pressure> screw injection machine; the barrel temperature and mold temperature are high, and the injection pressure is low. To

5.3 Time

The time required to complete an injection molding process is called the injection molding cycle.

6. Formulation of plastic molding process regulations According to the use requirements of plastic parts and the process characteristics of plastics, the correct molding method is selected, the molding process and molding process conditions are determined, and the selection of plastic molds and molding equipment are rationally designed to ensure the smooth molding process Carrying out this series of work for the plastic parts to meet the requirements is usually called the formulation of the process specifications for the plastic parts.
It is a guiding technical document in plastic molding production and an important basis for organizing production. It runs through all stages of the production process and must be strictly implemented.6.1 Analysis of plastic parts

The shape and structure of the plastic part determine the structure of the mold, and it has a great influence on whether the plastic part can be formed smoothly and the quality after forming.

In order to ensure the quality of plastic parts, usually the following points need to be paid attention to:

6.1.1 Analysis of plastics

(1) Analysis of the performance of plastics
(2) Analysis of plastic process performance

6.1.2 Analysis of the structure, dimensions, tolerances, and technical standards of plastic parts

(1) Does the structure of the plastic part meet the requirements of molding processability?
(2) Dimensions, tolerances and technical standards of plastic parts

6.2 Determination of the molding method and process flow of plastic parts

According to the characteristics of the plastic, the requirements of the plastic parts, and the structure, saizi, production batch, use conditions and molding equipment of the plastic parts, a series of feasible molding programs are proposed. Through the comparative analysis of each plan, the best molding method of plastic parts is determined according to the actual production conditions on site. After the molding method of plastic parts is determined, the process flow should be determined.
6.3 Determination of molding process conditions

Appropriate process conditions should be selected for qualified plastic parts formed by various molding methods. There are many factors that affect the plastic molding process, and there are many process conditions that need to be controlled, and the relationship between the process conditions is very close. Naizvozvo, a comprehensive analysis must be made according to the characteristics and actual conditions of the plastic, and the more reasonable process conditions must be selected initially, and then tested During the molding process, the process conditions are gradually revised according to the actual situation of the molding of the plastic parts and the inspection results of the plastic parts. To

6.4 Selection of equipment and tools

When the molding method is determined, the appropriate molding equipment must be selected, and the relevant process and installation parameters of the equipment and mold must be checked. Different molding methods use different molding equipment. In addition to the molding equipment, other processes also need to select the corresponding equipment, and indicate the specifications and technical parameters of the equipment used in accordance with the process. To

6.5 Formulation of process documents

The preparation of process documents is to summarize the content and parameters of the above process regulations and determine them in the form of appropriate process documents as the basis for production preparation and production process. Plastic parts process card is the most important process document in production.