流道基础-模具类[中文2989字] 【中英文WORD】.zip
外文翻译系 别 机械工程系专 业机械设计制造及其自动化班 级学 号姓 名指导教师负责教师2016 年 6 月（外文翻译）1原文：原文：1.The basic of runner1.The basic of runnerThe runner is a channel machined into the mod plate to connect the sprue with the entrance(gate)to the impression.In the basic two-plate mod the runner is positioned on the surface while on the more complex designs the runner may be positioned below the parting surfaceThe wall of the runner channel must be smooth to prevent any restriction to flow.Also,as the runner has to be removed with the molding,there must be no machine marks left,which would tend to retain the runner in the mod plate.To ensure that these points are met,its desirable for the mod designer to specify that the runner(channel)is polished in line of draw.There are some other considerations for the designer to bear in mind:(i)the shape of the cross section of the runner,(ii)the size of the runner.Runner cross-section shape The cross-sectional shape of the runner used in a mod is usually one of four forms(Figure 4.2):fully round(a),trapezoidal(b),modified trapezoidal(c)and hexagonal(d).The reason why these particular forms are used in preference to others are outlined below.The criterion of efficient runner design is that the runner should provide a maximum cross-sectional area from the standpoint of pressure transfer and minimum cross-sectional area to periphery will,therefore,give a direct indication of the efficiency of the runner design;the runner section are giver in Figure 4.3.As can be seen,the various types of standpoint;whereas the ratios exhibited by the semicircular and rectangular types make their use generally undesirable.Unfortunately,the square runner is not very satisfactory either,but for another reason:it is difficult to eject.In practice,because of this,an angle of 10is incorporated on the runner well,thus modifying the square to the trapezoidal section.The volume of the trapezoidal runner is approximately 25%greater than that of a round runner with corresponding dimensions(W=D,Figure 4.2).To reduce this difference and still maintain corresponding dimensions,a modified trapezoidal form has been developed(Figure 4.2c)in which the volume is only 14%greater(approximately)than its round counterpart.The hexagonal runner is basically a double trapezoidal runner,where the cross-sectional area of this runner type is about 82%of that of the corresponding round runner.Naturally if similar cross-sectional areas are required,then the value for D(Figure 4.2c)must be increased accord the hexagonal runner compared with matching the two halves of a round runner.This point applies particularly to runners which are less 3mm(1/8 in)in width.As the plastic melt progresses through the runner and mod system the melt adjacent to the cold mod surface will rapidly decrease in temperature and solidify.The material which follows will pass through the center of this solidified material and,because of the low（外文翻译）2thermal conductivity that most thermoplastics posses,the solidified material acts as an insulation and maintains the temperature of the central melt flow region.Ideally,the gate should therefore be positioned in line with the center of the runner to receive the material from the central flow stream.This condition may be achieved with the fully round runner(Figure 4.4a),and also with the hexagonal runner The basic trapezoidal designs(Figure 4.2b and c)are not as satisfactory in this respect since the gate cannot normally be positioned in line with the central flow stream.The main objection to the fully round runner is that this runner is formed from two semicircular channels machined one in each of the mod plates.It is essential that these channels are accurately matched to prevent an undesirable and inefficient runner system being developed.A similar argument applies to the hexagonal runner system.The fact that these channels must be accurately matched means that the mod cost for a mod containing round or hexagonal runner will be greater than for one containing trapezoidal runners.The choice of runner section is also influenced by the question whether positive ejection of the runner system is possible.Consider,for instance,the case of a two-plate mod in which a circular runner has been machined from both parting surface.In this case,as the mod opens,the runner is pulled from its channel in one mod half and it is then ejected from the other mod half either directly,by ejector pins,or by relying on its attachment to the moldings by the gates(Figure 4.5).For multi-plate molds,however,positive ejection of the runner system is not practicable.Here the basic trapezoidal-type runner is always specified,the runner channel being machined into the injection half from which it is pulled as the mod opens.In this way the runner is free to fall under gravity between mod plates.If a circular runner had been pecified,however,the runner system could well adhere to its channel and make its removal difficult(Figure 4.6).Summing up the points concerning cross-sectional shape,we can say that for simple two-plate molds which have a flat parting surface the fully round runner or hexagonal runner is to be prefaced,the increased mod cost being relatively small.For molds which have complex parting surface,where it would be difficult to match accurately the semicircular channels of the round runner or,for multi-plate molds,the trapezoidal or modified trapezoidal section should be used.2.Runner size2.Runner sizeWhen deciding the size of the runner the designer must consider the following factors:(i)the wall section and volume of the molding(ii)the distance of the impression from the main runner or sprue,(iii)runner cooling considerations,(iv)the range of mouldmakers cutters available and(v)the plastics material to be used.(i)The cross-sectional area of the runner must be sufficient to permit the freezes and for packing pressure to be applied for shrinkage compensation if required,Because of this,runners below 2 mm(3/32 in)diameter are seldom used and even this diameter is normally limited to branch runners under 25mm(1 in)in length.(ii)The further the plastic melt has to travel alone the runner the greater is the resistance to flow.Hence the distance the impression is from the sprue has a direct bearing on the（外文翻译）3choice of cross-sectional size of the runner.For example,whereas a 5mm(3/16 in)(iii)The cross-sectional area of the runner should not be such that it controls the injection cycle,although this is sometimes unavoidable for very light moldings The larger he cross-sec tion area of the runner the greater is the bulk of material it contains and the longer the period it takes to cool sufficiently to enable the mod to be opened and the moldings and runner ejected.For this reason it is undesirable to make the runner larger than 10 mm(in)diameter for most materials.However,the rigid PVCs and the acrylics are exceptions due to their high viscosity and diameters up to 13 mm(1/2 in)are used.(iv)The size chosen for the runner should be in a range consistent with the mouldmakerss not having to carry in stock a multitude of different!sizes of cutters.In practice the following are the more common sizes:2-13 mm in I mm steps in the metric range and-?in With in steps in the imperial unit range.The following empirical formula is suggested as a guide of the size of the runner or branch runner for moldings weighing up to 200g(I g(7 oz),and with wall sections less than 3 mm(0.125 in).For the rigid PVCs and the acrylics,increase the calculated diameter by 25%.The formula is used in conjunction with the notes given previously.(i)The runner should not be below 2 mm(3/32 in)diameter,nor above 10 mm(3/8 in)diameter(or 13 mm(1/2 in)diameter where applicable).(ii)The calculated size should be increased to the next suitable cutter size Figure 4.7 shows a plot of diameter versus length of runner for various weights of molding,adopting the metric system of dimensioning.Figure 4.8 shows a corresponding plot using the Imperial dimensioning system.For example,a 120 g(4 oz)molding in polyethylene being fed by a 50 mm(2 in)long runner will require a diameter of 7 mm(5/16 in).Theoretically the cross-sectional area of the main runner should be equal to,or in excess of,the combined cross-sectional areas of the branch runners that it is feeding.This relationship is,however,ignored when the maximum suggested diameter is reached The main objection to the fully round runner is that this runner is formed from two semicircular channels machined one in each of the mod plates.It is essential that these channels are accurately matched to prevent an undesirable and inefficient runner system being developed.A similar argument applies to the hexagonal runner system.The fact that these channels must be accurately matched means that the mod cost for a mod containing round or hexagonal runner will be greater than for one containing trapezoidal runners.The choice of runner section is also influenced by the question whether positive ejection of the runner system is possible.Consider,for instance,the case of a two-plate mod in which a circular runner has been machined from both parting surface.In this case,as the mod opens,the runner is pulled from its channel in one mod half and it is then ejected from the other mod half either directly,by ejector pins,or by relying on its attachment to the moldings by the gates(Figure 4.5).For multi-plate molds,however,positive ejection of the runner system is not practicable.Here the basic trapezoidal-type runner is always specified,the runner channel being machined into the injection half from which it is pulled as the mod opens.In this way the runner is free to fall under gravity between mod plates.If a circular runner had been（外文翻译）4specified,however,the runner system could well adhere to its channel and make its removal difficult 3.Runner layout3.Runner layoutThe layout of the runner system will depend upon the following factors:(i)the number of impressions,(ii)the shape of the components,(iii)the type of mod(i.e.,two-plate or multi-plate mold),(iv)the type of gate.There are two main considerations when designing a runner layout.The runner length should always be kept to a minimum to reduce pressure losses,and the runner system should be balanced.(i)The cross-sectional area of the runner must be sufficient to permit the freezes and for packing pressure to be applied for shrinkage compensation if required,Because of this,runners below 2 mm(3/32 in)diameter are seldom used and even this diameter is normally limited to branch runners under 25mm(1 in)in length.(Runner balancing means that the distance the plastic material travels from the sprue 1o the gate should be the same for each molding This system ensures that all the impressions will fill uniformly and without interruption providing the gate lands and the gate areas are identical,Figure 4.9 shows example of molds all based on the balanced runner principle.译文：译文：流道基础流道基础 流道是在模板上加工出的连接主流道和进入（浇口）型腔的一条沟槽。在两板式基本模具中，流道设置在分型面上而在较复杂的设计中流道也许设置在分型面的下面。流道的壁必须光滑，防止料流受到阻碍。另外，由于流道废料必须和塑件一起取出，所以流道壁上必须不留下任何加工痕迹，避免流道废料滞留在模板上。为了确保这些要点得到满足，要求模具设计者在图纸中注明这条流道需要沿取出方向抛光。另外还有一些要求设计者用心考虑的：（1）流道的横截面形状，（2）流道的尺寸和（3）流道的布置。模具中用到的流道横截面形状，通常是四种形式之一（图4.2）：整圆（a），梯形（b）,U 型（c），和六角形（d）。为什么采用这些特殊的形状而不采用其他形状的理由说明如下。流道设计效率的评判标准从压力传递的角度来看流道应该具有最大的横截面积，而从热量传递的角度来看，应该和周边有最小的接触面积。因此横截面积和周长的比率将直接可以指示流道设计的效率。这个值较高时，效率也高。各种类型流道横截面（外文翻译）5的比率如图 4.3 所示。可见从这种角度考虑圆形和方形的流道是两种最满意的设计。而半圆和矩形的比率使得它们通常很少使用。可是，方形的流道由于另一个原因，也不能另人满意：就是顶出困难。实际上由于这个原因，在流道的直壁上，设计了一个 10 度的斜度，从而修改成梯形截面。梯形流道的体积在相同尺寸的（W=D,）情况下，大约比圆形流道大 25%。为了减少这个不同，并且仍然维持相同的尺寸，改进后的梯形如图 4.2c 所示，这个体积比之圆形的增加量大约只有 14%。六角形流道基本上是两个梯形，在分型面上相对吻合。其横截面积大约是对应圆形流道的 82%。当然，假如要求相似的横截面积，则 D 值必须相应地增加。某些模具工认为，六角形流道和圆形流道相比前者在两半模上的吻合较为方便。这点尤其适用在流道宽度尺寸少于 3mm 的情况。当塑料熔体通过流道和模腔时，邻近冷的模腔表面的熔体将快速降温而固化。其后的料流将穿过这些已经固化的材料中心，由于大多数热塑性塑料所具有的低热传导率，已固化的材料起到了隔热作用并维持了中心料流的温度。因此理论上，浇口应该位于流道的中心线上，从中心料流获得材料。这种效果可以从整圆流道得到，也可以从六角形流道得到。一般的梯形流道设计难以在这方面得到满足，因为其浇口通常不能定位在料流的中心线上。）整圆流道的主要问题是这种流道是由分别加工在两块模板上的两个半圆合成的。所以把这两个流道精确地吻合防止流道系统发生不良组合和效率受阻的现象。对六角形流道也有类似的问题。由于这些流道必须精确地吻合，使得采用圆形或六角形流道的模具比梯形流道的模具的成本高。流道截面的选择也受到流道系统的顶出是否实际可行的影响。例如，考虑两板式模具中已经在分型面的两边加工成圆形流道的情况。这种情况下，当开模时，模具一侧的流道废料被从流道中拉出，然后在另一半模具中或直接被顶杆顶出或被连接在塑件上的浇口废料带出。可是对于多模板的模具，流道系统的可靠顶出是不可能的。这时，总是采用基本的梯形流道设计，其流道开在注射半模上，当开模时流道废料被拉出。然后在重力的作用下，从模板之间自然下落。如果这时设计了圆形流道的话，流道系统可能会粘滞在流道壁上，使得流道废料的去除发生困难。总结有关横截面形状的几点，我们可以说，对于具有平面分型面的简单两板式模具选用整圆或六角形流道较好，模具的成本增加相对较少。对于具有复杂分型面的模具，或对于多模板模具，由于圆形流道的两半圆难以精确地吻合，应该采用梯形的或U 形截面的流道。（外文翻译）6流道尺寸流道尺寸在决定流道尺寸时，设计者必须考虑以下因素：（1）塑件的壁厚和体积,（2）主流道或分流道距离型腔的尺寸，（3）流道冷却条件，（4）模具工使用的刀具尺寸范围和（5）所使用的塑料。（1）流道的横截面积必须满足允许熔体在流道冻结之前通过和充满型腔，并且使得补缩所需要的保压压力能作用到型腔。因此很少使用小于 2 毫米（3/32in）直径的流道，甚至这种尺寸的流道通常限于在长度在 25 毫米（in）以下的分流道上使用（2）此外，塑料熔体必须克服流道内的流动阻力。因此型腔和主流道之间的距离，直接和流道横截面尺寸的选择有关。例如，一个 5 毫米（3/16in）直径的流道也许适合于一个距离主流道 25 毫米的重量为 60 克（2 oz）的塑件，但与主流道的距离为 100 毫米的同样塑件却要求 7 毫米直径的流道（3）流道的横截面积应该不影响到注塑周期，尽管对于非常轻的塑件来说这是不可避免的。流道的横截面积越大，它所包含的材料体积也越大从而由于要使这部分材料冷却到模具可以开模顶出塑件和流道的时间周期也越长。由此对于大多数材料来说不希望流道的直径大于 10 毫米（3/8in）。不过对于硬 PVCs 和聚丙烯除外，这是由于它们所具有的高黏度决定的，其可用的直径可以达到 13 毫米。尺寸的选择应该在模具工常备的刀具尺寸范围之内。实际上以下是较常用的尺寸：2-13 毫米，在公制范围内以每 1 毫米为间隔；1/8-1/2in，在英制范围内以 1/16in为间隔。建议以下列经验公式作为流道或分流道尺寸的确定指导，用于塑件重量在200 克（7oz），而且所有的壁厚小于 3 毫米（0.125in）。对于硬 PVCs 和聚丙烯，计算得到的直径值增加 25%。这个公式必须和前述的注释联合使用.（1）流道直径应该不小于 2 毫米，不超过 10 毫米（或在适当时不超过 13 毫米）。（2）计算后的尺寸应该向上圆整到合适的刀具尺寸。图 4.7 表示的是不同塑件重量时，流道长度和对应流道直径的关系图。使用的是公制单位。图 4.8 表示的是英制单位。例如，一个 120 克的聚乙烯塑件，流道长度是50 毫米（2in），所要求的直径是 7 毫米（5/16in理论上，主流道的横截面积应该等于或超过由主流道供料的分流道的横截面积的组合。但是当已经达到建议的最大直径时这种关系可以忽略。整圆流道的主要问题是这种流道是由分别加工在两块模板上的两个半圆合成的。所以把这两个流道精确地吻合防止流道系统发生不良组合和效率受阻的现象。对六角形流道也有类似的问题。由于这些流道必须精确地吻合，使得采用圆形或六角形流道的模具比梯形流道的模具的成本高。流道截面的选择也受到流道系统的顶出是否实际可行的影响。例如，考虑两板式模具中已经在分型面的两边加工成圆形流道的情况。这种情况下，当开模时，模具一侧的流道废料被从流道中拉出，然后在另一半模具中或直接被顶杆顶出或被连接在塑件上的浇口废料带出。（图 4.5）可是对于多模板的模具，流道系统的可靠顶出是不可能的。这时，总是采用基本的梯形流道设计，其流道开在注射半模上，当开模时流道废料被拉出。然后在重力的（外文翻译）7作用下，从模板之间自然下落。如果这时设计了圆形流道的话，流道系统可能会粘滞在流道壁上，使得流道废料的去除发生困难。（图 4.6）流道的布置流道的布置流道系统的布置取决于下列因素：（1）型腔数目，（2）塑件的形状，（3）模具的类型（即，两板式或多板式模具），（4）浇口的类型。在计划一个流道布置方式时，有两个方面要重点关注。流道的长度应该总是维持到最小，以减小压力损失，流道系统要平衡。（1）流道的横截面积必须满足允许熔体在流道冻结之前通过和充满型腔，并且使得补缩所需要的保压压力能作用到型腔。因此很少使用小于 2 毫米（3/32in）直径的流道，甚至这种尺寸的流道通常限于在长度在 25 毫米（in）以下的分流道上使用.流道平衡意味着对于每个塑件而言，塑料从主流道到浇口的流通距离应该是相同的。假如浇口的长度和截面积相同，系统要求确保所有的型腔将均匀地充满而没有阻断现象。
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外文翻译系 别 机械工程系专 业机械设计制造及其自动化班 级学 号姓 名指导教师负责教师2016 年 6 月（外文翻译）1原文：原文：1.The basic of runner1.The basic of runnerThe runner is a channel machined into the mod plate to connect the sprue with the entrance(gate)to the impression.In the basic two-plate mod the runner is positioned on the surface while on the more complex designs the runner may be positioned below the parting surfaceThe wall of the runner channel must be smooth to prevent any restriction to flow.Also,as the runner has to be removed with the molding,there must be no machine marks left,which would tend to retain the runner in the mod plate.To ensure that these points are met,its desirable for the mod designer to specify that the runner(channel)is polished in line of draw.There are some other considerations for the designer to bear in mind:(i)the shape of the cross section of the runner,(ii)the size of the runner.Runner cross-section shape The cross-sectional shape of the runner used in a mod is usually one of four forms(Figure 4.2):fully round(a),trapezoidal(b),modified trapezoidal(c)and hexagonal(d).The reason why these particular forms are used in preference to others are outlined below.The criterion of efficient runner design is that the runner should provide a maximum cross-sectional area from the standpoint of pressure transfer and minimum cross-sectional area to periphery will,therefore,give a direct indication of the efficiency of the runner design;the runner section are giver in Figure 4.3.As can be seen,the various types of standpoint;whereas the ratios exhibited by the semicircular and rectangular types make their use generally undesirable.Unfortunately,the square runner is not very satisfactory either,but for another reason:it is difficult to eject.In practice,because of this,an angle of 10is incorporated on the runner well,thus modifying the square to the trapezoidal section.The volume of the trapezoidal runner is approximately 25%greater than that of a round runner with corresponding dimensions(W=D,Figure 4.2).To reduce this difference and still maintain corresponding dimensions,a modified trapezoidal form has been developed(Figure 4.2c)in which the volume is only 14%greater(approximately)than its round counterpart.The hexagonal runner is basically a double trapezoidal runner,where the cross-sectional area of this runner type is about 82%of that of the corresponding round runner.Naturally if similar cross-sectional areas are required,then the value for D(Figure 4.2c)must be increased accord the hexagonal runner compared with matching the two halves of a round runner.This point applies particularly to runners which are less 3mm(1/8 in)in width.As the plastic melt progresses through the runner and mod system the melt adjacent to the cold mod surface will rapidly decrease in temperature and solidify.The material which follows will pass through the center of this solidified material and,because of the low（外文翻译）2thermal conductivity that most thermoplastics posses,the solidified material acts as an insulation and maintains the temperature of the central melt flow region.Ideally,the gate should therefore be positioned in line with the center of the runner to receive the material from the central flow stream.This condition may be achieved with the fully round runner(Figure 4.4a),and also with the hexagonal runner The basic trapezoidal designs(Figure 4.2b and c)are not as satisfactory in this respect since the gate cannot normally be positioned in line with the central flow stream.The main objection to the fully round runner is that this runner is formed from two semicircular channels machined one in each of the mod plates.It is essential that these channels are accurately matched to prevent an undesirable and inefficient runner system being developed.A similar argument applies to the hexagonal runner system.The fact that these channels must be accurately matched means that the mod cost for a mod containing round or hexagonal runner will be greater than for one containing trapezoidal runners.The choice of runner section is also influenced by the question whether positive ejection of the runner system is possible.Consider,for instance,the case of a two-plate mod in which a circular runner has been machined from both parting surface.In this case,as the mod opens,the runner is pulled from its channel in one mod half and it is then ejected from the other mod half either directly,by ejector pins,or by relying on its attachment to the moldings by the gates(Figure 4.5).For multi-plate molds,however,positive ejection of the runner system is not practicable.Here the basic trapezoidal-type runner is always specified,the runner channel being machined into the injection half from which it is pulled as the mod opens.In this way the runner is free to fall under gravity between mod plates.If a circular runner had been pecified,however,the runner system could well adhere to its channel and make its removal difficult(Figure 4.6).Summing up the points concerning cross-sectional shape,we can say that for simple two-plate molds which have a flat parting surface the fully round runner or hexagonal runner is to be prefaced,the increased mod cost being relatively small.For molds which have complex parting surface,where it would be difficult to match accurately the semicircular channels of the round runner or,for multi-plate molds,the trapezoidal or modified trapezoidal section should be used.2.Runner size2.Runner sizeWhen deciding the size of the runner the designer must consider the following factors:(i)the wall section and volume of the molding(ii)the distance of the impression from the main runner or sprue,(iii)runner cooling considerations,(iv)the range of mouldmakers cutters available and(v)the plastics material to be used.(i)The cross-sectional area of the runner must be sufficient to permit the freezes and for packing pressure to be applied for shrinkage compensation if required,Because of this,runners below 2 mm(3/32 in)diameter are seldom used and even this diameter is normally limited to branch runners under 25mm(1 in)in length.(ii)The further the plastic melt has to travel alone the runner the greater is the resistance to flow.Hence the distance the impression is from the sprue has a direct bearing on the（外文翻译）3choice of cross-sectional size of the runner.For example,whereas a 5mm(3/16 in)(iii)The cross-sectional area of the runner should not be such that it controls the injection cycle,although this is sometimes unavoidable for very light moldings The larger he cross-sec tion area of the runner the greater is the bulk of material it contains and the longer the period it takes to cool sufficiently to enable the mod to be opened and the moldings and runner ejected.For this reason it is undesirable to make the runner larger than 10 mm(in)diameter for most materials.However,the rigid PVCs and the acrylics are exceptions due to their high viscosity and diameters up to 13 mm(1/2 in)are used.(iv)The size chosen for the runner should be in a range consistent with the mouldmakerss not having to carry in stock a multitude of different!sizes of cutters.In practice the following are the more common sizes:2-13 mm in I mm steps in the metric range and-?in With in steps in the imperial unit range.The following empirical formula is suggested as a guide of the size of the runner or branch runner for moldings weighing up to 200g(I g(7 oz),and with wall sections less than 3 mm(0.125 in).For the rigid PVCs and the acrylics,increase the calculated diameter by 25%.The formula is used in conjunction with the notes given previously.(i)The runner should not be below 2 mm(3/32 in)diameter,nor above 10 mm(3/8 in)diameter(or 13 mm(1/2 in)diameter where applicable).(ii)The calculated size should be increased to the next suitable cutter size Figure 4.7 shows a plot of diameter versus length of runner for various weights of molding,adopting the metric system of dimensioning.Figure 4.8 shows a corresponding plot using the Imperial dimensioning system.For example,a 120 g(4 oz)molding in polyethylene being fed by a 50 mm(2 in)long runner will require a diameter of 7 mm(5/16 in).Theoretically the cross-sectional area of the main runner should be equal to,or in excess of,the combined cross-sectional areas of the branch runners that it is feeding.This relationship is,however,ignored when the maximum suggested diameter is reached The main objection to the fully round runner is that this runner is formed from two semicircular channels machined one in each of the mod plates.It is essential that these channels are accurately matched to prevent an undesirable and inefficient runner system being developed.A similar argument applies to the hexagonal runner system.The fact that these channels must be accurately matched means that the mod cost for a mod containing round or hexagonal runner will be greater than for one containing trapezoidal runners.The choice of runner section is also influenced by the question whether positive ejection of the runner system is possible.Consider,for instance,the case of a two-plate mod in which a circular runner has been machined from both parting surface.In this case,as the mod opens,the runner is pulled from its channel in one mod half and it is then ejected from the other mod half either directly,by ejector pins,or by relying on its attachment to the moldings by the gates(Figure 4.5).For multi-plate molds,however,positive ejection of the runner system is not practicable.Here the basic trapezoidal-type runner is always specified,the runner channel being machined into the injection half from which it is pulled as the mod opens.In this way the runner is free to fall under gravity between mod plates.If a circular runner had been（外文翻译）4specified,however,the runner system could well adhere to its channel and make its removal difficult 3.Runner layout3.Runner layoutThe layout of the runner system will depend upon the following factors:(i)the number of impressions,(ii)the shape of the components,(iii)the type of mod(i.e.,two-plate or multi-plate mold),(iv)the type of gate.There are two main considerations when designing a runner layout.The runner length should always be kept to a minimum to reduce pressure losses,and the runner system should be balanced.(i)The cross-sectional area of the runner must be sufficient to permit the freezes and for packing pressure to be applied for shrinkage compensation if required,Because of this,runners below 2 mm(3/32 in)diameter are seldom used and even this diameter is normally limited to branch runners under 25mm(1 in)in length.(Runner balancing means that the distance the plastic material travels from the sprue 1o the gate should be the same for each molding This system ensures that all the impressions will fill uniformly and without interruption providing the gate lands and the gate areas are identical,Figure 4.9 shows example of molds all based on the balanced runner principle.译文：译文：流道基础流道基础 流道是在模板上加工出的连接主流道和进入（浇口）型腔的一条沟槽。在两板式基本模具中，流道设置在分型面上而在较复杂的设计中流道也许设置在分型面的下面。流道的壁必须光滑，防止料流受到阻碍。另外，由于流道废料必须和塑件一起取出，所以流道壁上必须不留下任何加工痕迹，避免流道废料滞留在模板上。为了确保这些要点得到满足，要求模具设计者在图纸中注明这条流道需要沿取出方向抛光。另外还有一些要求设计者用心考虑的：（1）流道的横截面形状，（2）流道的尺寸和（3）流道的布置。模具中用到的流道横截面形状，通常是四种形式之一（图4.2）：整圆（a），梯形（b）,U 型（c），和六角形（d）。为什么采用这些特殊的形状而不采用其他形状的理由说明如下。流道设计效率的评判标准从压力传递的角度来看流道应该具有最大的横截面积，而从热量传递的角度来看，应该和周边有最小的接触面积。因此横截面积和周长的比率将直接可以指示流道设计的效率。这个值较高时，效率也高。各种类型流道横截面（外文翻译）5的比率如图 4.3 所示。可见从这种角度考虑圆形和方形的流道是两种最满意的设计。而半圆和矩形的比率使得它们通常很少使用。可是，方形的流道由于另一个原因，也不能另人满意：就是顶出困难。实际上由于这个原因，在流道的直壁上，设计了一个 10 度的斜度，从而修改成梯形截面。梯形流道的体积在相同尺寸的（W=D,）情况下，大约比圆形流道大 25%。为了减少这个不同，并且仍然维持相同的尺寸，改进后的梯形如图 4.2c 所示，这个体积比之圆形的增加量大约只有 14%。六角形流道基本上是两个梯形，在分型面上相对吻合。其横截面积大约是对应圆形流道的 82%。当然，假如要求相似的横截面积，则 D 值必须相应地增加。某些模具工认为，六角形流道和圆形流道相比前者在两半模上的吻合较为方便。这点尤其适用在流道宽度尺寸少于 3mm 的情况。当塑料熔体通过流道和模腔时，邻近冷的模腔表面的熔体将快速降温而固化。其后的料流将穿过这些已经固化的材料中心，由于大多数热塑性塑料所具有的低热传导率，已固化的材料起到了隔热作用并维持了中心料流的温度。因此理论上，浇口应该位于流道的中心线上，从中心料流获得材料。这种效果可以从整圆流道得到，也可以从六角形流道得到。一般的梯形流道设计难以在这方面得到满足，因为其浇口通常不能定位在料流的中心线上。）整圆流道的主要问题是这种流道是由分别加工在两块模板上的两个半圆合成的。所以把这两个流道精确地吻合防止流道系统发生不良组合和效率受阻的现象。对六角形流道也有类似的问题。由于这些流道必须精确地吻合，使得采用圆形或六角形流道的模具比梯形流道的模具的成本高。流道截面的选择也受到流道系统的顶出是否实际可行的影响。例如，考虑两板式模具中已经在分型面的两边加工成圆形流道的情况。这种情况下，当开模时，模具一侧的流道废料被从流道中拉出，然后在另一半模具中或直接被顶杆顶出或被连接在塑件上的浇口废料带出。可是对于多模板的模具，流道系统的可靠顶出是不可能的。这时，总是采用基本的梯形流道设计，其流道开在注射半模上，当开模时流道废料被拉出。然后在重力的作用下，从模板之间自然下落。如果这时设计了圆形流道的话，流道系统可能会粘滞在流道壁上，使得流道废料的去除发生困难。总结有关横截面形状的几点，我们可以说，对于具有平面分型面的简单两板式模具选用整圆或六角形流道较好，模具的成本增加相对较少。对于具有复杂分型面的模具，或对于多模板模具，由于圆形流道的两半圆难以精确地吻合，应该采用梯形的或U 形截面的流道。（外文翻译）6流道尺寸流道尺寸在决定流道尺寸时，设计者必须考虑以下因素：（1）塑件的壁厚和体积,（2）主流道或分流道距离型腔的尺寸，（3）流道冷却条件，（4）模具工使用的刀具尺寸范围和（5）所使用的塑料。（1）流道的横截面积必须满足允许熔体在流道冻结之前通过和充满型腔，并且使得补缩所需要的保压压力能作用到型腔。因此很少使用小于 2 毫米（3/32in）直径的流道，甚至这种尺寸的流道通常限于在长度在 25 毫米（in）以下的分流道上使用（2）此外，塑料熔体必须克服流道内的流动阻力。因此型腔和主流道之间的距离，直接和流道横截面尺寸的选择有关。例如，一个 5 毫米（3/16in）直径的流道也许适合于一个距离主流道 25 毫米的重量为 60 克（2 oz）的塑件，但与主流道的距离为 100 毫米的同样塑件却要求 7 毫米直径的流道（3）流道的横截面积应该不影响到注塑周期，尽管对于非常轻的塑件来说这是不可避免的。流道的横截面积越大，它所包含的材料体积也越大从而由于要使这部分材料冷却到模具可以开模顶出塑件和流道的时间周期也越长。由此对于大多数材料来说不希望流道的直径大于 10 毫米（3/8in）。不过对于硬 PVCs 和聚丙烯除外，这是由于它们所具有的高黏度决定的，其可用的直径可以达到 13 毫米。尺寸的选择应该在模具工常备的刀具尺寸范围之内。实际上以下是较常用的尺寸：2-13 毫米，在公制范围内以每 1 毫米为间隔；1/8-1/2in，在英制范围内以 1/16in为间隔。建议以下列经验公式作为流道或分流道尺寸的确定指导，用于塑件重量在200 克（7oz），而且所有的壁厚小于 3 毫米（0.125in）。对于硬 PVCs 和聚丙烯，计算得到的直径值增加 25%。这个公式必须和前述的注释联合使用.（1）流道直径应该不小于 2 毫米，不超过 10 毫米（或在适当时不超过 13 毫米）。（2）计算后的尺寸应该向上圆整到合适的刀具尺寸。图 4.7 表示的是不同塑件重量时，流道长度和对应流道直径的关系图。使用的是公制单位。图 4.8 表示的是英制单位。例如，一个 120 克的聚乙烯塑件，流道长度是50 毫米（2in），所要求的直径是 7 毫米（5/16in理论上，主流道的横截面积应该等于或超过由主流道供料的分流道的横截面积的组合。但是当已经达到建议的最大直径时这种关系可以忽略。整圆流道的主要问题是这种流道是由分别加工在两块模板上的两个半圆合成的。所以把这两个流道精确地吻合防止流道系统发生不良组合和效率受阻的现象。对六角形流道也有类似的问题。由于这些流道必须精确地吻合，使得采用圆形或六角形流道的模具比梯形流道的模具的成本高。流道截面的选择也受到流道系统的顶出是否实际可行的影响。例如，考虑两板式模具中已经在分型面的两边加工成圆形流道的情况。这种情况下，当开模时，模具一侧的流道废料被从流道中拉出，然后在另一半模具中或直接被顶杆顶出或被连接在塑件上的浇口废料带出。（图 4.5）可是对于多模板的模具，流道系统的可靠顶出是不可能的。这时，总是采用基本的梯形流道设计，其流道开在注射半模上，当开模时流道废料被拉出。然后在重力的（外文翻译）7作用下，从模板之间自然下落。如果这时设计了圆形流道的话，流道系统可能会粘滞在流道壁上，使得流道废料的去除发生困难。（图 4.6）流道的布置流道的布置流道系统的布置取决于下列因素：（1）型腔数目，（2）塑件的形状，（3）模具的类型（即，两板式或多板式模具），（4）浇口的类型。在计划一个流道布置方式时，有两个方面要重点关注。流道的长度应该总是维持到最小，以减小压力损失，流道系统要平衡。（1）流道的横截面积必须满足允许熔体在流道冻结之前通过和充满型腔，并且使得补缩所需要的保压压力能作用到型腔。因此很少使用小于 2 毫米（3/32in）直径的流道，甚至这种尺寸的流道通常限于在长度在 25 毫米（in）以下的分流道上使用.流道平衡意味着对于每个塑件而言，塑料从主流道到浇口的流通距离应该是相同的。假如浇口的长度和截面积相同，系统要求确保所有的型腔将均匀地充满而没有阻断现象。
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