連接座支架注塑模設(shè)計(jì)-塑料注射模含12張CAD圖
連接座支架注塑模設(shè)計(jì)-塑料注射模含12張CAD圖,連接,支架,注塑,設(shè)計(jì),塑料,注射,12,十二,cad
外文資料翻譯
資料來源：www.elsevier.com
文章名：Tribological assessment of the interface injection mold/plastic part
書刊名：tribology international
作 者：crossmark
出版社：journal homepage
文 章 譯 名： 注塑模具原理及基本方法
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文原文:
The sector of plastics processing is relatively young compared to cast iron, steel or glass industry. So it still has a very strong development potential. One of the current challenges of the plastic injection process is linked to the importance given to product design that enables a strong differentiation
[1]. Plastic parts with an increased technical level of surface accuracy are required in the areas of luxury, packaging, automotive, including the medical and optics. Their development involves the improvement of the fabrication process, and one of the keys lies in the mastery of the surface conditions of the molds.
Injection molding is a cyclic process, characterized by 5 phases: dosing, injection, packing, cooling and ejection . The raw material that is dosed in the machine must be pure and conserved before use at an adequate temperature in order to be as dried as possible. This is necessary to avoid condensation inside the mold. The injection phase is characterized by high flow rates and hence high shear rate (tangential effect). As the molten material enters the mold, two heat transfer mechanisms occur: convection (between the melted material and mold surface) and viscous dissipation (due to the effect of injection speed on the injected material viscosity). As the filling is complete, the mold is uphold at a predetermined pressure and so the packing phase is initiated. During this phase, the molten polymer continues to be introduced into the mold to compensate for the shrinkage of the already injected material as it cools down. After a specific time, the cooling phase (contrary to the cooling state which begins during injection and packing phase) of the entire assembly starts and so also the solidification process of the plastic part. As the material solidifies and shrinks in the mold, the dominant heat transfer mechanism is conduction. When the part is sufficient solidified, it is ejected from the mold. During this last phase, a normal effect can be attributed to the ejection force and adhesion phenomena can occur between the mold surface and the plastic part
[2].
Despite the undeniable diversity of configurations available (in terms of combination: mold material, surface finish and processed materials), the producers are faced with similar difficulties. Thus, the key shortcomings that stand out, more or less combined, can be summarize as follows:
● the fouling phenomena which require frequent stops for cleaning;
● corrosion phenomena that can greatly limit the lifetime of the mold cavity as a function of the type of injected polymer;
● problems of sticking and releasing in function of the injected materials and surface quality;
● problems in keeping the polishing quality;
● scratches or shocks during use or storage.
The available literature approaches experimental and/or numerical, various aspects regarding the plastic injection molding process. One of them is the filling and flow behavior of molten polymers.
[3]Bociaga and Jaruga studied the formation of flow, weld and meld lines by developing a new method of flow visualization, which can prove helpful in the identification of weak
areas on injected parts. Also the effect of pressure and cavity thickness were assessed. Same topic was treated by Ozdemir etal.
[4], comparing the behavior of molten HDPE (high density poly-ethylene) and PE experimentally and numerically.
During molding, friction forces act first between the mold surface and the molten polymer and second when the plastic part is ejected from the mold. Bull etal.
[5] adapted the ASTM rubber wheel abrasion test to simulate the conditions of wear produced by the glass filled polymers on the barrel surface of an injection molding machine. Various coatings were tested, but unfortunately they tended to have a weak performance on account of the test conditions.
[6] developed a prototype apparatus to study the friction properties of molding thermoplastics during ejection phase. The measured friction coefficient had a tendency to increase with the roughness. But when the roughness was reduced the friction coefficient increase due to the rising adhesion forces effect. The scanning electron microscopy images of the mold surface and the ones for the polycarbonate (PC) and polypropylene (PP) plastic parts, revealed a clear replication of the mold surface on the parts.
Transient in nature, injection molding process involves not only several heat transfer mechanisms, phase change and time varying boundary conditions, but goes further in adding the effect of material properties and geometry of the injected part.
[7] Bendada etal performed a study to evaluate the nature of thermal contact between polymer and mold through the different phases of a typical injection cycle. Their findings concluded that the thermal contact resistance was not negligible, not constant with time and was strongly linked with the process conditions.
The existing number of studies concerning the phenomena present at the interface mold surface/polymer is relatively low to other related topics. Besides, they don’t focus on studying the current limitations of the plastic injection process at a microscopic scale, taking into account various macroscopic influences. To overcome plastic injection molding shortcomings, the contact conditions at the interface between mold surface and plastic part have to be identified. This work focus on the effect of the polishing quality, the mold geometry and the injected material on that interface, by studying the corrosion-mechanical attack and the mechanical -physical- chemical one.
2. Method and materials
2.1. Materials
Four polymers were chosen to be injected: ionomer resin (E-MMA Surlyns PC 2 000), styrene-acrylonitrile resin (SAN Tyril 790), polyamide with 25% glass fibers (PA66GF25) and poly-carbonate (PC Makrolon LQ 2647). Surlyn is a copolymer of ethylene and methacrylic acid where some of the acid groups are neutralized to form the sodium salt. The acid in the polymer gives polarity and reduces crystallinity. The ionic bonding between the polymer chains gives outstanding melt strength, toughness and clarity. The reason of choosing Surlyn was based on the experience of our industrial partners, which find it particularly corrosive despite its good properties. Surlyn is also a copolymer, optically transparent and brittle in mechanical behavior. It's considered in this study a reference material, usually used in cosmetics, luxury and automobile domains. PA66GF25 is an aliphatic-polyamide, reinforced with 25% glass fibers. PA66 has an excellent balance of strength, ductility and heat resistance. The glass fibers exert an abrasive effect and thus affect the mechanical protection of the polishing. PC is composed by carbonate groups. It has a high impact-resistance, low scratch-resistance and is highly transparent to visible light. It is usually used for the production of eyewear lenses and exterior automotive components.
2.2. Molds
Two molds, made of hardened steel (52 HRC) containing 13% to 15% of Chromium, with different geometries were used, one with a mirror polished surface (complex geometry) and another with an optical polished surface (simple geometry) . The mold has two parts: the stamp and the matrix. For the mold with complex geometry the stamp is of 149 119 80 mm in size and the matrix of 149 119 50 mm. In case of the one with a simple geometry, the stamp is of 50 70 mm in size and the matrix has a cylinder form with a diameter of 70 mm. The surface finish of the mirror and optical polished molds involved a polishing cloth and diamond paste. Further details on the polishing process are confidential.
The mirror polished mold was specially designed for this study by Technimold (a mold maker) to highlight the role of angles and obstacles in the formation of defaults. Also the mold design did not include a special feature that can evacuate the air. This was done intentionally in order to submit the polished surfaces to aggressive conditions. The molding process was performed at “Center Technique dela Plasturgie et des Composites” (IPC, France) on a 50 T Engel machine. The injection parameters, listed in Table 2, were chosen in accordance with standard specifications for the injected polymers. Based on a numerical simulation they were adapted to respond in conformity with the mold design. Two injection campaigns were conducted on this type of mold. After the first campaign, on the plane part of the mold stamp, an insert with a diameter of 12 mm and a height of 8 mm, was mounted to facilitate the morphology assessment.
For the Surlyn injection, 3000 parts were injected in the first campaign. After surface analysis, the mold was submitted to the industrial cleaning operation. The second campaign consisted in the injection of 3700 more parts. SAN and PA66GF25 were injected on the same mold. During the first campaign, only 8000 SAN parts were injected. Before starting a second campaign, the mold was polished entirely. The second campaign consisted in the injection of 300 parts of SAN. The insert was changed before starting the injection of 12 200 PA66GF25 parts.
2.3. Method
The surface expertize consisted in two main steps: the microscopy analysis and the inter ferometry measurements before and after injection process. Due to their large dimensions and elevated mass, the surface analysis of the mirror polished molds was per-formed using a classic optical microscope. For the optical polished one, thanks to smaller dimensions, the microscope analysis could be carried out using a numerical optical microscope (Keyence) and a high resolution environmental scanning electron microscope (FEI XL30 ESEM). Although two injection campaigns have been performed, the results presented in this paper, refer only to the surface expertize performed at the end of the second campaign. For the injected plastic parts, only the interface between mold matrix plane part and plastic part is discussed in this paper.
In order to identify the chemical composition of different deposits found on the mirror polished mold surfaces, a Fourier Transform Infrared (FTIR) spectrometer was used for the analysis.
3. Results and discussions
3.1. Mirror polished mold
3.1.1. Injection Surlyns
All along the stamp plane part, deposits different in texture and consistence can be observed (Fig. 5). Their location and morphology
seem to indicate the flow direction of the molten polymer. Also it can be noticed, towards the end of the flow, the deposits grow in terms of thickness and occupied surface.
The type of deposit observed in Fig. 5e and f is also observed after the first injection campaign (3000 injected parts), and appeared that the cleaning operation has been able to remove it, but formed again during the second injection campaign (3700 injected parts). This particular deposit is located between the extremity of the oval bump and the hole where one of the ejection pins acts. Also in this location the flow changes direction, more precisely makes a left turn; fact also revealed by the deposit morphology. Its existence can be explained starting with the effect of the injection speed on the molten polymer viscosity, which is considered to be a heat transfer mechanism that occurs during the injection process. Due to the geometry factor, the viscous dissipation creates a temperature gradient which sensitizes this area. During the packing phase, as the mold continues to be filled, the location identified is one of the last to be reached by the molten polymer. As the holding phase begins and with it the solidification, the temperature gradient that appears in the injection phase continues to act and by doing so it delays the solidification in this area. When the established time for the holding phase expires, the mechanism of ejection is set in motion. The ejection pin is close to the identified location and as it was affected by the temperature gradient and has not yet been entirely solidifies, it will also be the first area to be separated from the mold surface. All these can explain the appearance of the adhesion phenomenon.
In the deposit appears like a thin film and is also located in an area where the flow changes direction. It could also be justified by the temperature gradient, but its aspect and composition suggest that may another phenomena can occur. The infrared analysis performed on this area suggest that only some of the wave numbers match with the ones from the spectrum registered for the injected part It is possible that the gases released from the contact of the molten polymer with the mold surface reacted with the additives from the raw material composition and facilitated the separation of the thin layer that stick on the mold surface. Also the “scraped” aspect of this deposit indicates that is more likely that this type of deposit has formed during the injection phase.
Holes (form 14.6nm to 404nm deep) are observed before injection probably due to polishing.Their morphology evolves during injection process:the holes expand in occupation area and depth(39.7nm to 877nm).the pointing red arrows indicate the presence of the evolved holes.They exhibit two types of morphology.The first type illustrated shows very small holes focused altogether in smaller or larger spots and the second type illustrated presents a hole surrounded by a “cloud” of small holes.
Due to the inclusions in the bulk material,grains dislocation could occur causing the formation of holes during polishing process.Those holes are modified in term of depth and area during injection process.As reported,stress corrosion cracking can affect the molds,starting at a microscopic level and revealing itself at crack.The primary causal elements are the metallurgy of steel,the presence of chlorine in the water used in the cooling lines of the mold and the stresses on the tool during molding.It is known that Chromium gives the steel corrosion resistance,by providing a protective oxide layer.Thus it is possible that due to the polishing defects(holes),the thickness of the layer is compromised and thus when a high viscous corrosive polymer,like Surlyn,is injected,the areas affected by holes,are submitted to corrosion nature of Surlyn(based on the experience of industrial project partners),can create an aggressive environment at the mold/molten polymer interface due to the gases release.The high viscosity of Surlyn and its capability to stick onto the mold surface also plays a role in terms of exerting a mechanical-physico-chemical attack on the area where the defaults are located.All these statements allow to catalog this default as corrosion pit.
4. Conclusions
This study has allowed the identification and evaluation of defaults that occur during plastic injection process,at microscopic scale.The results obtained highlight the different damage mechanisms sustained by the mold surface,as a function of polishing,geometry and injected material.It can be also observed that for each material injected there is a difference of level of wear and damage mechanism between the stamp and the matrix.
Surlyn injection exhibited considerable amount of deposits on the mold stamp.It seems that the physico-chemical conditions,created during the injection by this type polymer,favored the adhesion.Also in the case ,the coupling effects of polishing quality,the injected material,adhesion and the lack of the mold feature that evacuates air,tend to form corrosion pits on a mirror polished surface.
SAN and PA66GF25 polymers were injected successively on the same mold.The mold surface presented polishing defaults(holes)before injection.The holes were enlarged in the direction perpendicular to the injection flow due to abrasive effect of glass fibers.
A critical characterization of the mold surface topography was performed in order to identify the location and the type of defaults that occur when more or less aggressive material were injected in molds with different geometries.All the results provided can be taken into consideration for the design of a “chameleon” coating that can overcome present drawback.
注塑模具原理與基本方法
譯文：與鑄鐵、鋼鐵或玻璃工業(yè)相比，塑料加工行業(yè)相對(duì)年輕。因此，它仍有很強(qiáng)的發(fā)展?jié)摿ΑＫ芰献⑸涔に嚹壳懊媾R的挑戰(zhàn)之一是與產(chǎn)品設(shè)計(jì)的重要性有關(guān)，從而使產(chǎn)品具有很強(qiáng)的差異性。
yǔ與 zhù鑄 tiě鐵 、 gāng鋼 tiě鐵 huò或 bō玻 li璃 gōng工 yè業(yè) xiāng相 bǐ比 ， sù塑 liào料 jiā加 gōng工 háng行 yè業(yè) xiāng相 duì對(duì) nián年 qīng輕 。 yīn因 cǐ此 ， tā它 réng仍 yǒu有 hěn很 qiáng強(qiáng) de的 fā發(fā) zhǎn展 qián潛 lì力 。 sù塑 liào料 zhù注 shè射 gōng工 yì藝 mù目 qián前 miàn面 lín臨 de的 tiǎo挑 zhàn戰(zhàn) zhī之 yī一 shì是 yǔ與 chǎn產(chǎn) pǐn品 shè設(shè) jì計(jì) de的 zhòng重 yào要 xìng性 yǒu有 guān關(guān) ， cóng從 ér而 shǐ使 chǎn產(chǎn) pǐn品 jù具 yǒu有 hěn很 qiáng強(qiáng) de的 chā差 yì異 xìng性 。
[1]. Plastic parts with an increased technical level of surface accuracy are required in the areas of luxury, packaging, automotive, including the medical and optics. Their development involves the improvement of the fabrication process, and one of the keys lies in the mastery of the surface conditions of the molds.
[ 1 ]在豪華、包裝、汽車等醫(yī)療和光學(xué)領(lǐng)域，要求提高表面精度的塑料件。它們的發(fā)展涉及到制造工藝的改進(jìn)，關(guān)鍵之一是掌握模具的表面條件。
注射成型是一個(gè)循環(huán)過程，其特征為5個(gè)階段：注射、注射、包裝、冷卻和脫模，在適當(dāng)?shù)臏囟认率褂们埃瑱C(jī)器中所含的原材料必須是純的和保守的，以便盡可能干燥。這是必要的，以避免在模具內(nèi)冷凝。注入階段的特點(diǎn)是高流速，因此高剪切速率（切向效應(yīng)）。當(dāng)熔融材料進(jìn)入模具時(shí)，會(huì)出現(xiàn)兩種傳熱機(jī)理：對(duì)流（熔化的材料和模具表面）和粘性耗散（由于注射速度對(duì)注入材料粘度的影響）。當(dāng)填充完成時(shí)，模具處于預(yù)定壓力下，從而開始填充階段。在這個(gè)階段，熔融的聚合物繼續(xù)被引入模具，以補(bǔ)償已經(jīng)注入的材料在冷卻過程中的收縮。在特定的時(shí)間之后，整個(gè)裝配過程中的冷卻階段（與注射和包裝階段開始的冷卻狀態(tài)相反）開始，也就是塑件的凝固過程。當(dāng)材料固化收縮時(shí)在模具，主要是傳導(dǎo)傳熱機(jī)理。當(dāng)零件充分凝固時(shí)，就會(huì)從模具中排出。在這最后一個(gè)階段，一個(gè)正常的效果可以歸因于脫模力和模具表面和塑件之間可能發(fā)生粘著現(xiàn)象。
[ 2 ]盡管配置的多樣性不可否認(rèn)，但在組合方面：模具材料、表面光潔度和加工材料，生產(chǎn)商也面臨類似的困難。因此，突出的關(guān)鍵缺點(diǎn)，或多或少地結(jié)合起來，可以總結(jié)如下：
jǐn盡 guǎn管 pèi配 zhì置 de的 duō多 yàng樣 xìng性 bù不 kě可 fǒu否 rèn認(rèn) （ zài在 zǔ組 hé合 fāng方 miàn面 ： mú模 jù具 cái材 liào料 、 biǎo表 miàn面 guāng光 jié潔 dù度 hé和 jiā加 gōng工 cái材 liào料 ） ， shēng生 chǎn產(chǎn) shāng商 yě也 miàn面 lín臨 lèi類 sì似 de的 kùn困 nan難 。 yīn因 cǐ此 ， tū突 chū出 de的 guān關(guān) jiàn鍵 quē缺 diǎn點(diǎn) ， huò或 duō多 huò或 shǎo少 de地 jié結(jié) hé合 qǐ起 lái來 ， kě可 yǐ以 zǒng總 jié結(jié) rú如 xià下 ：
●結(jié)垢現(xiàn)象需要頻繁啟停的清潔；
● jié結(jié) gòu垢 xiàn現(xiàn) xiàng象 xū需 yào要 pín頻 fán繁 qǐ啟 tíng停 de的 qīng清 jié潔 ；
●腐蝕現(xiàn)象，極大地限制了模具型腔的壽命作為一種注入聚合物型函數(shù)；
● fǔ腐 shí蝕 xiàn現(xiàn) xiàng象 ， jí極 dà大 dì地 xiàn限 zhì制 le了 mú模 jù具 xíng型 qiāng腔 de的 shòu壽 mìng命 zuò作 wéi為 yī一 zhǒng種 zhù注 rù入 jù聚 hé合 wù物 xíng型 hán函 shù數(shù) ；
●問題貼和釋放功能的注射材料和表面質(zhì)量；
● wèn問 tí題 tiē貼 hé和 shì釋 fàng放 gōng功 néng能 de的 zhù注 shè射 cái材 liào料 hé和 biǎo表 miàn面 zhì質(zhì) liàng量 ；
●保持拋光質(zhì)量問題；
●劃痕或沖擊使用或貯存過程中。
[ 3 ]現(xiàn)有文獻(xiàn)接近實(shí)驗(yàn)和/或數(shù)值，關(guān)于塑料注射成型過程的各個(gè)方面。其中之一是熔融聚合物的填充和流動(dòng)行為。Bociaga和Jaruga 研究了流的形成，焊縫和焊線通過流動(dòng)可視化的新方法，它可以在弱的鑒定證明是有益的注射部位。此外，壓力和空腔厚度的影響進(jìn)行了評(píng)估。同一主題采用Ozdemir etal。
[ 4 ]實(shí)驗(yàn)比較了熔融HDPE（高密度聚乙烯）和聚乙烯的行為。 在成型過程中，摩擦力首先作用于模具表面和熔融聚合物之間，其次是塑料部分從模具中排出。牛等。 [ 5 ]調(diào)整了ASTM橡膠輪磨損試驗(yàn)，模擬注塑機(jī)桶面上玻璃填充聚合物的磨損情況。各種涂層進(jìn)行了測(cè)試，但不幸的是，他們往往有一個(gè)弱的性能，由于測(cè)試條件。
[ 6 ]開發(fā)了一個(gè)原型裝置來研究成型熱塑性塑料在噴射階段的摩擦性能。測(cè)量的摩擦系數(shù)隨粗糙度增大而增大。但當(dāng)粗糙度降低時(shí)，由于粘著力的增加，摩擦系數(shù)增加。對(duì)模具表面和聚碳酸酯（PC）和聚丙烯（PP）塑料件的掃描電子顯微鏡圖像，揭示了模具表面上的部件清楚地復(fù)制。 在瞬態(tài)過程中，注塑過程不僅涉及到多種傳熱機(jī)理、相變和時(shí)變邊界條件，而且還涉及到注入部分材料性能和幾何形狀的影響。
zài在 shùn瞬 tài態(tài) guò過 chéng程 zhōng中 ， zhù注 sù塑 guò過 chéng程 bù不 jǐn僅 shè涉 jí及 dào到 duō多 zhǒng種 chuán傳 rè熱 jī機(jī) lǐ理 、 xiàng相 biàn變 hé和 shí時(shí) biàn變 biān邊 jiè界 tiáo條 jiàn件 ， ér而 qiě且 hái還 shè涉 jí及 dào到 zhù注 rù入 bù部 fen分 cái材 liào料 xìng性 néng能 hé和 jǐ幾 hé何 xíng形 zhuàng狀 de的 yǐng影 xiǎng響 。 B e n d a d a e t a l 。
[7] performed a study to evaluate the nature of thermal contact between polymer and mold through the different phases of a typical injection cycle. Their findings concluded that the thermal contact resistance was not negligible, not co
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