塑料模具设计中英文翻译006.docx

1、塑料模具设计中英文翻译006xxxxx大学毕业设计（论文）外文文献 学 院 xxxxxxxxxxx 专业班级 xxxxxxxxxxxxx 学生姓名 xxxxxxxxxxxxxxx 指导教师 xxxxxxxxxxxxxxx A. Mold ComponetsMolds used in injection molding consist of two halves; one stationary and one movable. The stationary half is fastened directly to the stationary platen and is in direct co

2、ntact with the nozzle of the injection unit during operation. The movable half of the mold is secured to the movable platen and usually contains the ejector mechanism. There are many possible mold designa, including multiple piece molds for complicated parts. On production molding equipment many art

3、icles may be shot at the same time by the use of multiple cavity molds. The use of a balanced runner system carries the plastic from the sprue to each individual cavity. At this poin the material passes through a gate into the cavity. The gate is a restriction, smaller then the runner, to provide fo

4、r even filling of the mold cavity and to allow the products to be easily removed form the runner system. With most injection molding system, the articles can be snapped away from the runner or sprue without additional trimming. Prouducts that have been injection molded can usually be identified by f

5、inding where the gate was broken off. The gate will usually be located at the edge or parting line of an object or in the center of cylindrical product. Molds are expensive, as are the machines. Yet, once the product has been designed, molds made, and production stared, articles can be produced in q

6、uantity at low cost. Virtually all thermoplastics can be injection molded through variations in mold and machine design. Mold (and die) parts that are mass-produced and standardized in shape and dimension are referred to as “standards” (or “standard parts”). Specialized operators of milling machines

7、, lathes, lathes, electronic discharge machining (EDN) equipment and grinders produce mold components independently of each other, following detaied mold part drawings. Finally, all these items come together with the standard mold base and hardware and are assembled by the mold maker. Today, standar

8、d components for the moldmaking industry are marketed by a number of companies. Fig.3.1.1 illustrate the standard components for Molds.Table 3.1.1 Status of standardization (1998) components for Compression, Injection, and Die-Cast MoldPos. No.DenominationStandardDINISO1Plate, plain16760-16753-22Pla

9、t, drilledV 16760-2/3Support pillarDIN ISO 10073100734Centring sleeve1675994495Locating guide pillar1676180176Locating guide busch1671680187Ejector pin, cylindrical head1530-A67518Shouldered ejector pin, cylindrical head1530-C86949Ejector pin, conical head1530-D/10Flat ejector pin1530-F869311Ejector

10、 sleeve16756840512Sprue puller insert16757/13Sprue bushing16752-11007214Angle pin/840415Locating unit, round and falt/840616Locating ring1676310907-110907-217Thermal insulating sheet167131560018Cooling connectors16766/B Mold Construction The construction of the mold for injection molding begins with

11、 the working drawing. From it the tequirements for the mold can be specified. These would include the material from which the mold should be made, the availability of equipment for machining the mold, and the mold capacity of the die set on the machine. Cold rolled steel is an ideal material for lab

12、oratory molds, since it machines well, is fairly inexpensive, and holds up well for nozzle pressure and wear. Its major disadvantage is that it will rust quickly unless protected by mold telease or wax during storage. Complicated mold cavities need specialized machining and polishing, therefore, cir

13、cular cavities which can be turned and polished on the lathe require less equipment and machining skill. Similar molds may also be machined from aluminum, and they have the advantage of not rusting. Excessive wear develops on the sprue due to the high nozzle pressure on the soft aluminum, but this c

14、an be overcome by the use of a steel cover plate on the top of the mold. Another method of mold construction is by the casting process using an aluminum filled epoxy resin. This type of mold is particularly suited to products of intricate design and products that are difficult to machine. The cast e

15、poxy is strong and gives good surface detail, however, it is brittle and should have a steel top plate attached to absorb the wear of the nozzle. A pattern of the product must be secured or made and placed on a mold plate. The drag of a small steel flask is placed around the pattern and the epoxy re

16、sin is poured to fill the mold half. When this half of the mold has been cured, the cope is placed over it and the remainder of the mold poured. Upon curing, the flask is removed, all surfaces machined smooth, dowel pinholes drilled, and dowels inserted. A steel cap plate should be bolted to the top

17、 halves and the sprue, runners, and gates machined. Instructions for mixing, pouring, and curing the aluminum filled epoxy should be followed according to the manufacturers specifications.2. Hot Runner Systems Hot runners are classified according as they are heated: insulated-runner systems (it is n

18、ot described in this article) and genuine hot-runner systems. The latter can be further sub-classified according to the type of heating: internal heating, and external heating. Heating is basically performed electrically by cartridge heaters, heating rods, band heaters, heating pipes and coils, etc.

19、 To ensure uniform flow and distribution of the melt, usually a relatively elaborate aontrol system comprising several heating circuits and an appropriate number of sensors is needed. The operating voltage is usually 220 V to 240 V, but small nozzles frequently have a low voltage of 5 V, and also 15

20、 V and 24 V operating voltage. Runner systems in conventional molds have the same temperature level as the rest of the mold because they are in the same mold block. If, however, the runner system is located in a special manifold that is heated to the temperature of the melt, all the advantages liste

21、d below accrue. Runner manifolds heated to melt temperature have the task of distributing the malt as far as the gates without damage. They are used for all injectionmolded thermoplastics as well as for crosslinking plastics, such as elastomers and thermosets. In the case of thermoplastics, these ma

22、nifolds are usually referred to as the hot-runner system, the hot manifold, or simply as hot runners. For crosslinking plastics, they are known as cold runners.A. Hot-Runner Systems Hot-runner systems have more or less become established for highly-automated production of molded thermoplatic parts t

23、hat are produced in large numbers. The decision to use them is almost always based on economics, i. e. production size. Quality considerations, which played a major role in the past, are very rare now because thermoplastics employed today are almost all so that they can be processed without difficul

24、ty with hot-tunner systems that have been adapted accordingly. Hot-tunner systems are available as standard units and it is hardly worthwhile having them made. The relevant suppliers offer not only proven parts but also complete systems tailored to specific needs. The choice of individual parts is l

25、arge.B. Economic Advantages and Disadvantages of Hot-Runner Systems 1. Economic Advantages Savings in materials and costs for regrind. Shorter cycles; cooling time no longer determined by the slowly solidifying runners; no nozzle retraction required. Machines can be smaller because the shot volume-a

26、round the runners-is reduced, and the clamping forces are smaller because the runners do not generate reactive forces since the blocks and the manifold block are closed. 2. Economic Disadvantages Much more complicated and considerably more expensive. More work involved in running the mold for the fi

27、rst time. More susceptible to breakdowns, higher maintenance costs (leakage, failure of heating elements, and wear caused by filled materials). 3. Technological Advantages Process can be automated (demolding) because do not need to be demolded. Gates at the best position; thanks to uniform, precisel

28、y controlled cooling of the gate system, long tlow paths are possible. Pressure losses minimized, since the diameter of the runners is not restricted. Artificial balancing of the gate system; balancing can be performed during running production by means of temperature control or special mechanical s

29、ystem (e. g. adjustment of the gap in a ring-shaped die or use of plates in flow channel. Natural balancing is better). Selective influencing of mold filling; needle valve nozzles and selective actuation of them pave the way for new technology (cascade gate system: avoidance of flow lines, in-mold d

30、ecoration). Shorter opening stroke needed compared with competing, conventional three-platen molds. Longer holding pressure, which leads to less shrinkage. 4. Technological Disadvantages Risk of thermal damage to sensitive materials because of long flow paths and dwell times, especially on long cycl

31、es. Elaborate temperature control required because non-uniform temperature control would cause different melt temperatures and thus non-uniform filling.C. Design of a Hot-Runner System and its Components Hot-runner molds are ambitious systems in a technological sense that involve high technical and

32、financial outlay for meeting their main function of conveying melt to the gate without damage to the material. D. Externally/Internally Heated Systems The major advantages and disadvantages of the two types .E. Externally Heated System 1. Advantage Large flow channel cause low flow rare and uniform temperature distribution. 2. Disadvantage The temperatures required for external heating have to be very mu