外文翻譯--盡量減少生產(chǎn)成本的超薄注塑成型

1、<p>　　Minimizing manufacturing costs for thin injection molded plastic components</p><p>　　1. Introduction</p><p>　　In most industrial applications, the manufacturing cost of a plastic p

2、art is mainly governed by the amount of material used in the molding process. </p><p>　　Thus, current approaches for plastic part design and manufacturing focus primarily on establishing the minimum part thi

3、ckness to reduce material usage. </p><p>　　The assumption is that designing the mold and molding processes to the minimum thickness requirement should lead to the minimum manufacturing cost.</p><p

4、>　　Nowadays, electronic products such as mobile phones and medical devices are becoming ever more complex and their sizes are continually being reduced. </p><p>　　The demand for small and thin plastic com

5、ponents for miniaturization assembly has considerably increased in recent years.</p><p>　　Other factors besides minimal material usage may also become important when manufacturing thin plastic components. &l

6、t;/p><p>　　In particular, for thin parts, the injection molding pressure may become significant and has to be considered in the first phase of manufacturing.</p><p>　　Employing current design appro

7、aches for plastic parts will fail to produce the true minimum manufacturing cost in these cases.</p><p>　　Thus, tackling thin plastic parts requires a new approach, alongside existing mold design principles

8、and molding techniques.</p><p>　　1.1 Current research</p><p>　　Today, computer-aided simulation software is essential for the design of plastic parts and molds. Such software increases the effic

9、iency of the design process by reducing the design cost and lead time [1]. </p><p>　　Major systems, such as Mold Flow and C-Flow, use finite element analysis to simulate the filling phenomena, including flow

10、 patterns and filling sequences. Thus, the molding conditions can be predicted and validated, so that early design modifications can be achieved. Although available software is capable of analyzing the flow conditions, a

11、nd the stress and the temperature distribution conditions of the component under various molding scenarios, they do not yield design parameters with minimum m</p><p>　　The output data of the software only gi

12、ve parameter value ranges for reference and leaves the decision making to the component designer. Several attempts have also been made to optimize the parameters in feeding [4–7], cooling [2,8,9], and ejection These att

13、empts were based on maximizing the flow ability of molten material during the molding process by using empirical relation ships between the product and mold design parameters. </p><p>　　Some researchers have

14、 made efforts to improve plastic part quality by Reducing the sink mark [11] and the part deformation after molding [12], analyzing the effects of wall thickness and the flow length of the part [13], and analyzing the in

15、ternal structure of the plastic part design and filling materials flows of the mold design [14]. Reifschneider [15] has compared three types of mold filling simulation programs, including Part Adviser, Fusion, and Insigh

16、t, with actual experimental testing. Al</p><p>　　Studies applying various artificial intelligence methods and techniques have been found that mainly focus on optimization analysis of injection molding param

17、eters [16,17]. For in-stance He et al. [3] introduced a fuzzy- neuro approach for automatic resetting of molding process parameters. By contrast , Helps et al. [18,19] adopted artificial neural networks to predict the se

18、tting of molding conditions and plastic part quality control in molding. Clearly, the development of comprehensive molding</p><p>　　Generally, the current practical approach for minimizing the manufacturing

19、cost of plastic components is to minimize the thickness and the dimensions of the part at the product design stage, and then to calculate the costs of the mold design and molding process for the part accordingly, as show

20、n in Fig. 1.</p><p>　　The current approach may not be able to obtain the real minimum manufacturing cost when handling thin plastic components.</p><p>　　1.2Manufacturing requirements for a typi

21、cal thin plastic component As a test example, the typical manufacturing requirements for a thin square plastic part with a center hole, as shown in Fig. 2, are given in Table 1.</p><p>　　Fig.1. The current p

22、ractical approach</p><p>　　Fig.2. Test example of a small</p><p>　　plastic component </p><p>　　Table1. Customer requirements for the example component</p><p>　　2. The c

23、urrent practical approach</p><p>　　As shown in Fig.1, the current approach consists of three phases: product design, mold design and molding process parameter setting. A main objective in the product design

24、is to establish the physical dimensions of the part such as its thickness, width and length. The phases of molded sign and molding subsequently treat the established physical dimensions as given inputs to calculate the r

25、equired details for mold making and molding operations.</p><p>　　When applying the current practical approach for tackling the given example, the key variables are handled by the three phases as follows:<

26、/p><p>　　Product design</p><p>　　* Establish the minimum thickness (height) HP, and then calculate the material cost. HP is then treated as a predetermined input for the calculation of the costs of

27、 mold</p><p>　　design and molding operations. HP </p><p>　　Mold design</p><p>　　* Calculate the cooling time for the determined minimum</p><p>　　thickness HP in order t

28、o obtain the number of mold cavities required. The mold making cost is then the sum of the costs to machine the: </p><p>　　–Depth of cutting (thickness) HP</p><p>　　–Number of cavities</p>

29、<p>　　–Runner diameter DR</p><p>　　–Gate thickness HG</p><p>　　Molding process</p><p>　　* Determine the injection pressure Pin, and then the cost of power consumption</p&g

30、t;<p>　　Determine the cooling time t co, and then the cost of machine operations. The overall molding cost is the sum of the power consumption cost and machine operating cost.</p><p>　　The total manuf

31、acturing cost is the sum of the costs of plastic material, mold making and molding operations. Note that, in accordance with typical industry practice, all of the following calculations are in terms of unit costs.</p&

32、gt;<p>　　2.1 Product design </p><p>　　This is the first manufacturing phase of the current practical approach. The design minimizes the thickness HP of the plastic component to meet the creep loading

33、 deflection constraint , Y (<1.47mmafter1yearofusage),and to minimize plastic material usage cost Cm. Minimizing HP requires [21]:</p><p>　　Figure 3 plots changes in HP through Eqs.1 and 2.The graphs show

34、 that the smallest thickness that meets the 1.47mm maximum creep deflection constraint is 0 .75mm,with a plastic material cost of $0.000483558/unit and a batch size of 200000 units. </p><p>　　This thickness

35、will be treated as a given input for the subsequent molded sign and molding process analysis phases.</p><p>　　2.2Mold design</p><p>　　2.2.1 Determination of cooling time</p><p>　　Th

36、e desired mold temperature is 25 C. The determined thickness is 0.75mm. Figure 4 shows the cooling channels layout following standard industry practices. The cooling channel diameter is chosen to be 3mm for this example.

37、</p><p>　　From [22], the cooling time t co:</p><p>　　And the location factor, </p><p>　　BysolvingEqs.3and4, and substituting HP =0.75mm and the given values of the cooling channel d

38、esign parameters, the cooling time (3.1s) is obtained.</p><p>　　The cycle time t cycle, given by E q. 5, is proportional to the molding machine operating costs, and consists of injection time (t in), ejectio

39、n time (t e j), dry cycle time (t d c), and cooling time (t c o). </p><p>　　2.2.2 Determination of the number of mold cavities In general, the cost of mold making depends on the amount of machining work to f

40、orm the required number of cores/cavities, runners, and gates. The given example calls for a two-plate mold </p><p><b>　　Fig.3. </b></p><p>　　Deflection and plastic materials costs v

41、ersus part thickness Fig.4. Cooling channel layout that does not require undercut machining. Therefore, the ma chining work for cutting the runners and gates is proportional to the work involved in forming the cores/cavi

42、ties and need not be considered. In the example, mold making cost Cmm is governed by (n, HP).</p><p>　　Generally, the minimum number of cavities, Nmin, is chosen to allow for delivery of the batch of plastic

43、 parts on time圖3 。 </p><p>　　After substitution</p><p>　　which is rounded To n =3,since the mold cannot contain 2.64 cavities. The machine operation capacity and the lead-time of production in t

44、he example are given as 21.5h/d and 21d, respectively. Moreover, as mentioned in the previous section, the cycle time is directly proportional to the part thickness HP. A curve of batch size against thickness is plotted

45、in Fig. 5. As shown, at HP =0.75mm, the production capability (batch size) is 242470units.Thus the production capability of n =3 is larger than</p><p>　　For simplicity, the time taken for machining the depth

46、 of a thin component is treated as a given constant and added to the required time t CC for making a cavity insert. The C mm can then be calculated by n as expressed [1]</p><p>　　2.3Molding process</p>

47、<p>　　In the molding process, the cycle cost and power consumption cost are used to establish the molding operations cost as described in the following sections.</p><p>　　Fig.5. Mold making cost versu

48、s part thickness</p><p>　　2.3.1 Cycle cost</p><p>　　The cycle cost C is defined as the labor cost for molding machine operations. The calculation of cycle cost, given by E q. 8, mainly depends o

49、n the cycle time and number of mold cavities </p><p>　　For the example, the value of labor cost per hour, L, is given as $1.19/h. Also, Cp can be calculated, as t cycle =20.1sand n = 3 when HP = 0.75mm, as f

50、ound earlier. And so Cp =$0.0022147/unit.</p><p>　　2.3.2 Power consumption cost</p><p>　　Typically，within the operating cycle of a molding machine，maximum power is required during injection. Hen

51、ce, longer injection times and higher injection pressures increase the power consumption cost.</p><p>　　For the purposes of this example, an injection time of tin =0.5sisselectedand applied for the molding p

52、rocess。The required hydraulic power PH, power consumption E i, and cost CPC for injection can be found from the following</p><p>　　expressions [23]</p><p>　　In E q. 9, 0.8 is the mechanical adva

53、ntage of the hydraulic cylinder for power transmission during molding, and the resulting electric power cost of CE = HK$1.0476/kWh is given in E q. 11. To find CPC, the sum of the required injection pressures Pin in the

54、feeding system and cavity during molding need to be found.</p><p>　　Required injection pressures. Based on the mold layout design, the volume flow rate Q in the sprue is equal to the overall flow rate, and t

55、he volume flow rate in each primary and secondary runner will be divided by the separation number, Ni,</p><p>　　according to:</p><p>　　The volume flow rate in a gate and cavity equals to that of

56、 the runner connecting to them. Tan [24] derived simplified models</p><p>　　For filling circular and rectangul a r channels that can be employed for the feeding system design in this study </p><p&

57、gt;　　1. Sprue and runner (circular channel)</p><p>　　The pressure drop of sprue and runner is express e d a s:</p><p>　　2. Cavity and gate (rectangular channel)</p><p>　　The pressu

58、re drop of cavity and gate is expressed as: </p><p>　　Further, the temperature-dependent power law viscosity model can be defined as: </p><p>　　Based on the values of the volume flow rate and co

59、nsistency index m (T) for each simple unit, the pressure drop P can be found by using E q s. 12to15. Thus, the required filling pressure is the sum of pressure drops P in the sprue, primary runner, secondary runner, gat

60、e, and cavity:</p><p>　　Required power consumption. Given the shape and dimensions of the part and feeding channel, the pressure drops of the sprue , runner, gate , and cavity are obtained through the ca

61、lculation froE q s. 12 to 15, and are substituted into E q. 16. The required injection pressure Pin is calculated and substituted into the E q. 9.Combining E q s. 10 and 11, the power consumption cost CPC is calculated a

62、nd depends on the variation of injection pressure, which is indirectly affected by the thickness </p><p>　　After substitution, this becomes: </p><p>　　Then the molding cost</p><p>　

63、　After calculation, C molding = $0.0022147/unit+$0.003755/unit,when HP =0.75mm, n =3.</p><p>　　2.4Remarks on the current practical approach Based on Esq. 8 to 18 it can be shown that as the part thickness,H

64、p, increases, the necessary injection pressure Fig.6. Molding process cost versus thickness consumption cost) decreases but the cycle time (and thus labor cost) increases and so there is a minimum total molding process

65、cost, as shown in Fig.6 for the example in this study. As can be seen the minimum molding process cost is Hp =2.45mm.</p><p>　　If the test example part thickness, Hp, were increased from</p><p>

66、　　0.75 to 2.45mm, the plastic material cost is increased by</p><p>　　230.1%; however, the total molding process cost decreases by</p><p>　　20.6% to $0.004741/unit. Moreover, the total manufactur

67、ing cost for the part falls by9.54%, a saving of $0.0001174/unit.</p><p>　　Thus, applying the current practical approach does not give the true minimum manufacturing cost. The current practical approach main

68、ly focuses on minimizing the thickness of the part to reduce the plastic material usage and achieve shorter cooling times. When the part is thin, higher injection pressures are needed during the molding process, which su

69、bstantially increases the molding process costs and consequently shifts the true minimum manufacturing cost for the part away from the minimum thick</p><p>　　3 The proposed approach</p><p>　　To

70、overcome the shortcoming of the current practical approach, a concurrent approach is proposed for minimizing the manufacturing cost for plastic parts made by injection molding.</p><p>　　3.1Framework of the p

71、roposed approach</p><p>　　Three parallel phases of product design, mold design, and molding process setting are undertaken for the proposed approach showninFig.7. The parallel phases handle individual cost f

72、unctions for material cost, molding cost, and mold making cost,</p><p>　　Which add to yield the total manufacturing cost . The product shape and dimensions (the possible range of thicknesses) are considered

73、as the main design inputs at the beginning of design phase, as shown in Fig. 7.</p><p>　　The proposed approach will provide a possible solution by considering the three phases simultaneously. The outputs are

74、 options for combinations of the thickness of the part , the number of mold cavities , and the minimum manufacturing cost that meet all the given requirements.</p><p>　　Fig.8. Creep deflection and plastic ma

75、terial cost versus thickness</p><p>　　Fig.9. Mold making cost versus part thickness (n =1–8) </p><p>　　3.5 Molding phase</p><p>　　The molding process cost is the sum of cycle cost a

76、nd power consumption cost. Each number of mold cavities has its own curve of molding cost as shown in Fig. 10. Each curve is inversely proportion to the thickness of the plastic component. The lowest point of the curve i

77、s the minimum cost. Usually, when the curve has no sharp turning point and asymptotes, it means that enlarging the thickness cannot reduce molding cost very much.</p><p>　　If the thickness of product is incr

78、eased, lower injection pressure is required during molding, thus the power consumption cost is reduced, but the cycle time is lengthened and the cycle cost is increased.</p><p>　　As in Fig. 10, assuming an e

79、ight cavity mold, the thickness of the plastic part should be less than 2.81mm, with minimum molding cost lessthan$0.00475676/unit.mold</p><p>　　3.6Determination of manufacturing cost</p><p>　　A

80、s discussed, the results obtained in sections 3.3, 3.4, and 3.5 can be combined to yield a total manufacturing cost that is the summation of the part design, mold making, and molding process costs. Eight different curves

81、 have beendrawninFig.11, for the different numbers of mold cavities. The minimum manufacturing cost is obtained from the lowest point among the eight curves in this study. From Fig.11, the thickness of the plastic</p&

82、gt;<p>　　Fig.10. Molding process cost versus part thickness (n =1–8):</p><p>　　Fig.11. Manufacturing cost versus part thickness (n =1–8)</p><p>　　component is 1.44mm, with minimum manufac

83、turing cost of $0.00843177/unit and n =3.</p><p>　　The lowest manufacturing cost is obtained after inputting all values of thickness and numbers of cavities with in the allowable range, 0.01mm to 6mm and 1 t

84、o 8, respectively.</p><p>　　Table2. Comparison of results for the different approaches</p><p>　　3.7 Comparison of the approaches</p><p>　　The results for the current and proposed ap

85、proaches are summarized in Table 2.</p><p>　　When the thickness is increased from 0.75 to 1.44mm, the plastic material cost increases by 92%, but reduces total manufacturing cost by 72.4%. An improvement of

86、85.9% for the creep deflection is also obtained in the functional design. Further, with the 1.44mm papt thickness, </p><p>　　圖1 。目前切實(shí)可行的辦法</p><p>　　圖2 。試驗(yàn)的例子，一個(gè)小塑料元件</p><p>　　表1 ?？蛻?/p>

87、的需求為榜樣部分</p><p>　　2目前切實(shí)可行的辦法</p><p>　　在圖1所示，目前的辦法包括三個(gè)階段：產(chǎn)品設(shè)計(jì)，模具設(shè)計(jì)和成型工藝參數(shù)的設(shè)置。一個(gè)主要目標(biāo)的產(chǎn)品設(shè)計(jì)是建立在物理尺寸的一部分，如它的厚度，寬度和長(zhǎng)度。各階段的模塑成型和隨后簽署和處理建立物理尺寸作為給出的投入來(lái)計(jì)算所需的詳細(xì)資料和成型模具制造業(yè)務(wù)</p><p>　　當(dāng)申請(qǐng)目前切實(shí)可行的辦

88、法解決給定的例子，關(guān)鍵的變數(shù)是由三個(gè)階段處理如下：</p><p><b>　　產(chǎn)品設(shè)計(jì)</b></p><p>　　確定的最小厚度（高度） ，然后計(jì)算材料成本。HP則視為預(yù)先輸入的計(jì)算費(fèi)用的模具設(shè)計(jì)和成型業(yè)務(wù)。</p><p><b>　　模具設(shè)計(jì)</b></p><p>　　*計(jì)算冷卻時(shí)間確定最

89、低厚度HP，以獲得一些模具腔需要。模具制造成本是下列參數(shù)費(fèi)用的總和：</p><p><b>　　–切削深度（厚度）</b></p><p><b>　　–模具腔數(shù)量</b></p><p><b>　　–轉(zhuǎn)輪直徑</b></p><p><b>　　–G澆注系統(tǒng)厚度

90、</b></p><p><b>　　模具生產(chǎn)</b></p><p>　　* 確定射出壓力引腳，和能耗成本</p><p>　　確定共同的冷卻時(shí)間t ，和機(jī)器的成本運(yùn)作。整體成型費(fèi)用的總和，能耗成本和機(jī)器的運(yùn)行成本。</p><p>　　總制造成本是塑料材料費(fèi)用的總和，模具制造及成型工藝的總和。請(qǐng)注意，根據(jù)

91、典型的行業(yè)慣例，以下所有的計(jì)算方面的單位成本</p><p><b>　　2.1 產(chǎn)品設(shè)計(jì)</b></p><p>　　這是第一階段的制造業(yè)目前的實(shí)際做法。設(shè)計(jì)最小厚度HP的塑料組件，以滿足蠕變載入中撓度約束坐標(biāo)“ （ < 1.47mm經(jīng)過(guò)一年的使用 ） ，并盡量減少使用塑料材料成本。盡量減少厚度HP需要[ 21 ] ：</p><p>

92、　　圖3地塊的變化，HP通過(guò)Eqs.1和圖2表明，最小厚度符合一點(diǎn)四七毫米最大蠕變變形的制約因素是0 0.75毫米，以塑料材料費(fèi)用為$0.000483558/unit和一批規(guī)模200000單位。</p><p>　　這厚度將被視為一個(gè)特定的投入，隨后簽署和模壓成型過(guò)程的分析階段。</p><p><b>　　2.2模具設(shè)計(jì)</b></p><p&g

93、t;　　2.2.1測(cè)定冷卻時(shí)間</p><p>　　理想的模具溫度為25 c.在確定厚度0.75毫米。圖4顯示了冷卻通道布局下列標(biāo)準(zhǔn)行業(yè)慣例。冷卻通道直徑為3毫米作為例子。 </p><p>　　從[ 22 ] ，冷卻時(shí)間t的合作：</p><p><b>　　和位置的因素</b></p><p>　　通過(guò)求解Eqs.3

94、和4 ，而代以HP= 0.75毫米和提供價(jià)值的冷卻通道的設(shè)計(jì)參數(shù)，獲得冷卻時(shí)間（ 3.1s ）。通過(guò)圖9.5得到循環(huán)周期的時(shí)間t ，是成正比的成型機(jī)運(yùn)營(yíng)成本，并包括注射時(shí)間 ，澆注時(shí)間 ，干燥周期時(shí)間 ，和冷卻時(shí)間。</p><p>　　2.2.2一般來(lái)說(shuō)一些模具腔，模具制造費(fèi)用的數(shù)額取決于加工的工作，形成所需數(shù)目的核心/腔，橫澆道，和澆注系統(tǒng)。給定的例子叫做兩板模具</p><p>&

95、lt;b>　　圖3 。 </b></p><p>　　撓度及塑膠原料成本與部分厚度</p><p>　　圖4。冷卻通道的布局，不需要削弱加工。因此，在機(jī)器工作的切削加工澆道和澆口所涉及的工作，形成了核心/腔，不必加以考慮。在這個(gè)例子中，模具制造成本轉(zhuǎn)換是由（n，HP）給與 。 </p><p>　　一般而言，最低數(shù)量的型腔數(shù)， Nmin ，由及時(shí)運(yùn)

96、送的一批塑料零件所選擇</p><p><b>　　再替代，</b></p><p>　　這是四舍五入到n = 3 ，因?yàn)槟＞卟荒馨?.64</p><p>　　該機(jī)器操作能力和準(zhǔn)備時(shí)間的生產(chǎn)實(shí)例為21.5h / d和21d。此外，提到在上一節(jié)中，周期時(shí)間是成正比的。曲線的批量大小對(duì)厚度在圖5中繪制 。如表所示，在HP= 0.75毫米，年生產(chǎn)

97、能力（批處理大?。┦?42470units.由于生產(chǎn)能力n=3大于所需的批量（ 200000units ） 。 </p><p>　　為了簡(jiǎn)潔明了，所需要的時(shí)間用于加工的深度，為了模具腔插入薄薄的部分將被視為某一常數(shù)和增加所需的時(shí)間tCC為了模具腔插入。在C毫米然后可以計(jì)算由N所表達(dá)[ 1 ]</p><p><b>　　2.3成型過(guò)程</b></p>

98、<p>　　在成型過(guò)程中，周期成本和能耗的費(fèi)用是用來(lái)建立以下各節(jié)中所描述的成型工藝成本。 </p><p>　　圖5 。模具制造成本與部分厚度</p><p><b>　　2.3.1周期成本</b></p><p>　　該周期成本C是指成型機(jī)操作的勞動(dòng)成本。計(jì)算周期成本，因?yàn)橥ㄟ^(guò)E q。8 ，主要依賴于周期的時(shí)間和模具腔數(shù)量：<

99、/p><p>　　例如，勞動(dòng)力成本的價(jià)值每小時(shí)C L, is given as $1.19/h. Also, Cp can be calculated, as t cycle =20.1sand n = 3 when HP = 0.75mm, as found earlier. And so Cp =$0.0022147/unit.</p><p><b>　　2.3.2能耗費(fèi)用&l

100、t;/b></p><p>　　通常情況下，營(yíng)業(yè)周期內(nèi)的成型機(jī)，最大功率時(shí)需要注射。因此，較長(zhǎng)時(shí)間和較高的注射液注射壓力增加了能耗成本。 </p><p>　　就本條而言，例如，注射時(shí)間tin = 0.5sisselectedand用于成型過(guò)程。所需的液壓動(dòng)力PH值，耗電量和成本每次注射可從下表 [ 23 ] ：</p><p>　　在E q.9 ， 0.8是

101、機(jī)械利用液壓缸輸電成型，以及由此產(chǎn)生的在Eq.11均衡器上電力成本的CE= HK$1.0476/kWh。若要尋找CPC的總和，需要注射壓力Pin的進(jìn)給系統(tǒng)和腔成型過(guò)程中所需要的注射壓力?；谀＞叩牟季衷O(shè)計(jì)，體積流量Q在澆道等于總流量和流速的數(shù)量在每個(gè)初級(jí)和中級(jí)階段將被離職數(shù)量所分割， </p><p><b>　　通過(guò)</b></p><p>　　體積流量澆注系統(tǒng)和腔

102、等于該轉(zhuǎn)輪將它們連接在一起。 [ 24 ]簡(jiǎn)化模型推導(dǎo)</p><p>　　填補(bǔ)圓形和rectangul河渠道，可受聘為進(jìn)給系統(tǒng)的設(shè)計(jì)研究</p><p>　　1.直澆道和橫澆道（圓形澆道） </p><p>　　壓降直澆道和橫澆道是表示edas</p><p>　　2. 腔和澆口（矩形澆口） </p><p>　　壓

103、降腔和澆口表示為：</p><p>　　此外，溫度依賴電力法粘度模型可以被界定為</p><p>　　所需的電力消耗。由于形狀和尺寸的一部分和feeding channel，壓降的直澆道，橫澆道，澆口，和腔的壓力降是通過(guò)計(jì)算來(lái)獲得的。</p><p>　　E q s. 12 到 15, 并代入E q. 16。所需注射壓力Pin和代入計(jì)算的E q. 9.Combini