<P>jiey ,when i studied in univercity, it`s cost me lots of time to learn english .</P><P>i cant enjoy that time .</P><P>at that time ,i spent 0.5 hours on physics everyday , i got 87 in the end of the term .</P><P>at that time ,i spent at least 1.5 hours on english ,but i only can pass the exam !</P><P>it`s unfair![em04]</P>
<P>I agree with you, jiey. I use English edition also. for me the commands just icons to me.</P>
<P>but I can't found such articles and even if I have, I can't translate them into English.</P>
<P>I support you, but my ability don't allow me to.</P></DIV>
<P>jiey ,when i studied in univercity, it`s cost me lots of time to learn english .</P>
<P>i cant enjoy that time .</P>
<P>at that time ,i spent 0.5 hours on physics everyday , i got 87 in the end of the term .</P>
<P>at that time ,i spent at least 1.5 hours on english ,but i only can pass the exam !</P>
<P>it`s unfair![em04]</P></DIV>
<P>I have the same condition with you : )</P>
<P>as you know, Language is so profound and have accompanied human for thousands years, and a phylum(语系) is much different from another , so I think there is no subject can be more difficult to learn.</P>
<P>Injection time switchover
Temperature affects the viscosity of the melt, which presents resistance to the advance of the screw. Increased resistance slows down the screw and prevents the cavity from filling in the given injection time. On the other hand, reduced resistance would lead to overpacking. Injection time switchover is the only means available in injection moulding machines without screw position and pressure sensors.</P><P>
注射时间转换
温度影响熔融塑料的粘度，而粘度会给螺杆的顶部带来阻力（反压力）。增加的阻力是螺杆（旋转、前进）速度降低，在设定的注射时间里阻止模腔的填充。另一方面，降低的阻力则可能导致过充填。注射时间转化是在注射成型机里唯一可用的不需要（设定、改变）螺杆位置和压力传感器的（解决上述问题）手段。</P>
<P>Screw position switchover
Screw position switchover is not affected by temperature nor viscosity. This is the preferred method in machines with screw position potentiometer. Like injection time switchover, screw position switchover could be considered open-loop as screw position is not a direct measure of volumetric filling. A leaky nozzle misleads the machine computer into switching over before the cavity is filled. So could a worn screw valve and a worn injection cylinder. Furthermore, if the screw diameter is large relative to (the cube root of) the mould cavity volume, variation of 0.1 mm could give an overpacked or underpacked fill. Despite its deficiencies, this is the most widely used switchover method in a modern injection moulding machine most probably because it is a standard (not optional) feature.</P><P>螺杆位置转换</P><P>螺杆位置转换不受温度和粘度的影响。在有螺杆位置测定计的机台中，这是首选的方法（我见过的都有哦），和射出时间转换一样，螺杆位置转换被认为是开环的（这个好像不是正确翻译），因为螺杆位置不是测定充填量的直接手段。喷嘴有泄漏会误导机台计算机在模腔还没有被填满的时候就开始转换。磨损（磨破）的螺杆阀门（是止逆环吧）和磨损的注射油缸也会误导。此外如果螺杆直径相对于模腔体积（的立方根）很大，0.1mm的变化量（转换处螺杆位置的变化量）就会产生过充填和充填不足。尽管有很多缺陷，这仍然是现代注射成型机中最有可能运用最广泛的转换方法，因为它（螺杆）是标准部件（不是附加的）。
</P>
3 Hydraulic pressure switchover
The packing of the melt in the mould cavity has to be balanced by the hydraulic pressure driving the screw forward. A rise in the hydraulic pressure during injection could be used to signal the switchover. Due to a roughly 10:1 ratio between the twin injection cylinders and the screw cross sectional areas, the injection cylinder hydraulic pressure is less than the screw tip pressure by the same ratio. The pressure drop at the runners and sprue gate separates the cavity pressure from the screw tip pressure. The compressibility of the melt (between the cavity and the screw tip) delays the time the pressure is felt. As a result, hydraulic pressure is not an accurate detector of the volumetric filling point.
However, hydraulic pressure switchover does have the advantage of the sensor working in a congenial environment (oil temperature below 50oC, oil pressure at system pressure (usually 140 bars)) and the sensing is independent of the mould (not attached to the mould). Hydraulic pressure sensor is usually an option in an modern injection moulding machine.
Hydraulic pressure, nozzle pressure and cavity pressure sensing locations are shown in Figure 11.
液压缸压力转换
熔融塑料在模腔的填充平衡需要液压缸压力驱动螺杆前进来保证。注射过程中液压压力的增加可以用来给转换发个信号。因为同套设备中的油缸柱塞和螺杆的截面积比例大概是是10：1，所以相同速率(前进速度吧,柱塞怎么转动?)的液压缸柱塞压力要远小于螺杆顶端的压力.在分流道以及主流道浇口处的压力降将模腔压力和螺杆顶端压力区分开(此处区分开就是产生很大差别).(模腔和螺杆顶部之间的)塑料的可压缩性会延迟压力感应的时间.其结果是,液压压力不能精确的探测充填适度饱和的那个位置.
然而液压压力有其他的优势:传感器工作环境适宜(油温低于50摄氏度,油压就是系统油压(一般140巴(一种压力单位))),感应与模具无关(因为并没有附在模具上).液压传感器是现代注射机的一个常见选择(我接触过的传感器主要有机械触摸式的,学名近接开关;光电感应然后就是这个液压式的)
液压缸压力、喷嘴压力、模腔压力的感应位置如图11所示。
<DIV class=quote><B>以下是引用<I>yanleye</I>在2005-1-26 15:56:04的发言：</B>
<P>you are the best one, thank you !</P>
<P>and i have a question : do the two，clamping pressure and clamping force ，have the same meaning?
</P></DIV>
<P>you are welcome!</P>
<P>用在clamping后面都是锁紧力的意思</P>
<P>个人感觉clamping pressure适合于液压锁模，而clamping force用在机械式上面</P>
<P>不知道是不是错觉？</P>
<P><FONT color=#ff0000>终于弄明白了，pressure指均匀载荷，而force是集中的，pressure = force per unit area.</FONT></P>
Nozzle pressure switchover
Nozzle pressure is also called injection pressure, which is the pressure of the melt in the nozzle or at screw tip. Nozzle pressure switchover is improved over hydraulic pressure as the compressibility of the melt cushion is avoided. The environment is harsher (melt temperature below 400oC, melt pressure at 1400 bars, the melt could be corrosive/abrasive), and the sensor face must be flush with the barrel interior wall. This switchover method is not often used except in research.
Figure 12. Nozzle pressure sensor 图12 喷嘴压力感应器
喷嘴压力转换
喷嘴压力也叫注射压力，是熔融塑料在喷嘴或者螺杆顶端（所受）的压力。喷嘴压力转换比液压缸压力转换好的地方是避免了用于缓冲的熔融塑料的可压缩性（的问题）。（感应器所处）环境很恶劣（熔融塑料温度400以下，压力1400吧，熔融塑料可能具有腐蚀性和磨损性），并且感应器必须与料筒内壁平齐。这种转换方法除了研究中（使用，）一般不经常使用。
Cavity pressure switchover
The most accurate measure of volumetric filling is via cavity pressure. Two methods are in common use: direct and indirect. In direct cavity pressure measurement, a sensor in the mould senses the melt pressure in the cavity. Direct cavity pressure measurement is the more accurate of the two, but requires one to drill a hole at the mould for the sensor. Since it is inconvenient to remove the sensor, one needs to dedicate at least one sensor per mould. In a multicavity mould, cavity pressure measurement requires one sensor per cavity, increasing the sensor investment further.
Figure 13. Direct cavity pressure sensor 图13直接型模腔压力传感器
In indirect pressure measurement, a force sensor is placed behind an ejector pin the other end of which is in contact with the melt. Cavity pressure could be calculated from force/ejector pin cross sectional area. The temperature at the sensor is much less than that of the melt. With indirect cavity pressure switchover, the sensor is not dedicated to the mould (mould independent), which comes in handy when mould changing is often. It also reduces the sensor investment. Due to the friction at the ejector pin, indirect cavity pressure sensing is less accurate than its direct cousin.
Figure 14. Indirect cavity pressure sensor 图14间接型模腔压力传感器
Where the required quality on the surface of the moulded parts does not allow marks either by the sensor or the ejector pin, a strain sensor that measures mould deformation could be used. After calibration in a test mould (which has a cavity pressure sensor), it may be used for cavity pressure measurement in the production mould (which does not have a cavity pressure sensor but has the calibrated strain sensor).
A device based on cavity pressure sensing could detect the volumetric filling point accurately. Switchover could be initiated by comparing the actual pressure with a set value equals to the cavity pressure at point 3 in Figure 9.
Alternatively, Kistler has developed SmartAmp which detects the volumetric filling point. SmartAmp contains a charge amplifier for the quartz type cavity pressure sensor and a chip which uses the principles of artificial intelligence to detect the kink in the pressure curve at volumetric filling. Usually, the learning takes the first few shots.
模腔压力转换
最精确的填充量的测量方法是通过模腔压力（测量）。两种方法用处一样：直接和间接。在直接模腔压力测量中，模具中的感应器感应模腔内压力。直接模腔压力测量比较精确，但是需要在模具里面钻个孔来安装感应器。因为感应器移动不方便，需要给每个穴专门配至少一个感应器。在多穴模具中模腔压力测量需要没穴一个感应器，增加了投资成本。
在间接模腔压力测量中，一个力的感应器被安置在与熔融塑料接触的顶针的后面。模腔压力可以通过力/顶针横截面计算出（感测出）。感应器的温度比熔融塑料的温度要低很多。通过间接模腔压力转换，感应器不是专用于模具（某个独立的模具），如果换模频繁的话用起来很方便。也降低了对感应器的投资。由于顶针的摩擦，间接模腔压力感应没有直接的准确。
<P 0cm 0cm 0pt; TEXT-ALIGN: left; mso-pagination: widow-orphan" align=left><B>文章名称：Quality injection moulding<p></p></B></P><P 0cm 0cm 0pt; TEXT-ALIGN: left; mso-pagination: widow-orphan" align=left><B><p> </p></B></P><P 0cm 0cm 0pt; TEXT-ALIGN: left; mso-pagination: widow-orphan" align=left><B>1. Introduction</B> <p></p></P><P 0cm 0cm 0pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align=left>Injection moulding without rejects is the ideal moulders try to attain. This article describes two auxiliary devices that could increase the repeatability of an injection moulding machine. Once the optimum parameters are set, the physical dimensions, weight and other physical properties of the part will stay almost constant. The two devices do clamping force measurement/control and cavity pressure switchover to holding pressure. <p></p></P><P 0cm 0cm 0pt; TEXT-ALIGN: left; mso-pagination: widow-orphan; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto" align=left>避免不良品的注射成型是很多成型工艺员努力想达到的理想。这篇文章会介绍两种辅助装置，他们可以增强注射机的重现性。一旦设定了合适的成型参数，产品的实体尺寸，重量和其他物理性能将保持稳定。这两个装置就是锁紧力量测/控制装置和（射出）转保压的模腔压力转化装置。<p></p></P>
For injection moulding of high precision optical parts, or parts with a high added value like appliance cases, the payoff of reduced rejects is high. Figure 1 shows the part weight distribution of quality moulding and suboptimal moulding. The nominal weight is 60 g, allowable deviation is +0.1 g and -0.05 g. The white cubes denote parts within the tolerance band.
对于高精密光学产品或有附加价值的产品—-如重要器械，减少不良品所产生的利润非常高。图一显示了高品质成型和低品质成型所生产产品的重量分布。标准重量是60克，允许偏移量从负0.05克到正0.1克。白色方块表示产品重量在公差带内。
2.1 Toggle clamp
A 5-point double toggle clamp is shown in Figure 2. After amplification by the toggle mechanism, the clamping cylinder, attached to the tail platen, extends, pushing the moving platen to lock the mould halves together. We will investigate in various ways how the clamping force is generated.
2.1 曲肘式锁紧
图2显示了一个“五点双曲肘锁紧装置”（专业翻译是怎样的？）。经过曲肘机构的放大，安在动模固定板的锁紧油缸前进，从而推动动模固定板使两个半模合在一起，我们将用不同的方法来研究缩紧力是怎么产生的。
|小黑屋|手机版|模具论坛
( 浙ICP备15037217号 )
发表于 2005-1-25 08:20:00
楼主
/5 
