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1、Lesson 5 Sprue Bush and Register Ring,The sprue bush is defined as that part if the mould in which the sprue is formed.,In practice the sprue bush is the connecting member between the machine nozzle and the mould face, and provides suitable aperture through which the material can travel on its way t
2、o the impressions or to the start of the runner system in multi-impression moulds.,The sprue bush is fairly highly stressed in some applications and should therefore be made from a nickel chrome steel and should always be hardened.,Note that while initially the nozzle may have been set up correctly,
3、 an increase in the injection cylinder temperature will cause a fairly high force to be applied to the sprue bush because of the expansion of the injection cylinder.,The internal aperture of the sprue bush has between 2and 4included taper, which facilitates removal of the sprue from the mould at the
4、 end of molding cycle.,For reference, 2; 2.6; 3 and 4 are the included tapers adopted by various standard parts suppliers.,There are two basic designs of sprue bush which differ only with respect to the form of seating between the sprue bush and nozzle of the machine. Both design are shown (Figure 5
5、-1(a) (c).,The first of these is a sprue bush with a spherical recess which is used in conjunction with a spherical front ended nozzle as illustrated (Figure 5-1(a).,The second has a perfectly flat rear face, the seating between it and its corresponding nozzle being shown (Figure 5-1(c).,Figure 5-1
6、Sprue and nozzle (a) spherical; (c) flat; (b) (d) illustrating effect of misalignment between sprue bush and nozzle,Providing the alignment between the nozzle and the bush apertures is perfect, a leak-free joint is achieved with the spherical seating.,It should be noted that the radius on the nozzle
7、 is slightly less than that in the bush, which ensures both parts are in physical contact at the apertures.,However, if the nozzle and sprue bush are slightly out of line (due perhaps to wear on platen bushes) a gap will result and leakage behind the mould will develop (Figure 5-1(b).,This drawback
8、is not present if slight misalignment occurs at the seating of the sprue bush and flat-faced nozzle (Figure 5-1(d).,As can be seen, no leakage can occur if the two apertures are slightly out of the line and no restriction to flow will occur either, providing that the sprue bush has an aperture sligh
9、tly larger than that of the nozzle.,An allowance of o.8 mm on diameter is usually made.,Register ring,The register ring is a circular member fitted on to the front face (and often also to the rear face) of the mould. Its purpose is to register (or locate) the mould in its correct position on the inj
10、ection machine.,When the mould is mounted on the machine the front mounted register ring fits into a circular hole which is accurately machined in the injection platen on the cylinder-nozzle axis.,This ensures that the small aperture in the nozzle is in direct alignment with the sprue bush.,Now, sin
11、ce the sprue bush is the connecting member between the machine nozzle and the mould face, this alignment of nozzle aperture and sprue bush hole permits an uninterrupted flow of material from the cylinder, through the nozzle and sprue hole into the mould runner system.,The register ring, in fact, for
12、ms a direct connection between the sprue bush and the hole in the injection platen of the machine. (Figure 5-2),Figure 5-2 Register ring,Notes, Note that while initially the nozzle may have been set up correctly, an increase in the injection cylinder temperature will cause a fairly high force to be
13、applied to the sprue bush because of the expansion of the injection cylinder.,注意：尽管喷嘴（最初）已经正确安装，但是注射油缸膨胀将引起注射油缸温度升高，进而产生相当高的力施加到浇口套上（引起浇口套和喷嘴错位）。,句中that是宾语从句修饰note，because of the expansion of the injection cylinder修饰an increase in the injection cylinder temperature。, As can be seen, no leakage can o
14、ccur if the two apertures are slightly out of the line and no restriction to flow will occur either, providing that the sprue bush has an aperture slightly larger than that of the nozzle.,从图中也可以看出，如果浇口套的孔径比喷嘴的稍微大些，那么即使安装时两个孔稍微偏移同轴线，也不会发生漏料现象，同时也不会对熔体流动产生阻力。,句中and 连接两个并列的句子，if the two apertures are slightly out of the line修饰no leakage can occur。,
