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山东铝合金压铸缺陷-氧化夹渣原因!

来源:http://www.jnhjgs.cn     发布时间:2021-05-21 13:24:54    点击:

山东铝合金压铸缺陷-氧化夹渣原因:
The reason of the defect oxidation slag inclusion in Shandong Aluminum alloy die casting is as follows
炉料不清洁,回炉料使用量过多
The charge is not clean and the amount of returned charge is too much
浇注系统设计不良
Poor gating system design
合金液中的熔渣未清除干净
The slag in the alloy liquid is not cleaned up
浇注操作不当,带入夹渣
Improper pouring operation leads to slag inclusion
精炼变质处理后静置时间不够
The standing time after refining modification is not enough
通过对铝合金压铸的报废件分析,浇口夹渣主要有3种形态:缩孔类、油污类和冷硬层。其中以油污类的夹渣数量居多,占夹渣总数的60%以上;冷硬层占夹渣总数的35%左右;而缩孔类占夹渣总数的5%。
According to the analysis of scrap parts of aluminum alloy die casting, there are three main forms of slag inclusion in gate: shrinkage cavity, oil stain and cold hard layer. Among them, the amount of oily sludge is the most, accounting for more than 60% of the total amount of slag; The cold hard layer accounts for about 35% of the total slag inclusions; The shrinkage cavity accounts for 5% of the total slag.
1、类似缩孔缺陷
1. Similar shrinkage defects
当敲掉铝合金压铸件浇道料饼后,浇口处出现呈不规则形状、内部比较干净、表面粗糙的类似缩孔状的孔洞。缩孔类夹渣的铝合金压铸件浇口表面凹陷,打磨涂装后外观仍不光洁。产生原因是内浇口温度比较高(实测高模温为380℃),是后续凝固的部位,造成该处Al液来不及补缩,产生缩孔缺陷。
When the runner cake of aluminum alloy die casting is knocked out, the shrinkage like holes with irregular shape, clean interior and rough surface appear at the gate. The gate surface of aluminum alloy die casting with shrinkage cavity and slag inclusion is concave, and the appearance is not smooth after grinding and coating. The reason is that the temperature of the inner gate is relatively high (the measured high mold temperature is 380 ℃), which is the subsequent solidification position, resulting in the lack of time for Al liquid feeding, resulting in shrinkage defects.
                                             山东铝合金压铸
2、油污类缺陷
2. Oil pollution defects
每一铸造循环需向冲头加注润滑油,冲头油在Al液浇注后没有完全燃烧,被包裹在Al液中形成杂质一起填充到型腔。由于包裹有冲头油的Al液温度较低,会较早凝固,流动速度慢,因而在填充末了时停留在产品末端。加之内浇口截面积小,流动阻力大,这部分包裹有冲头油且提前凝固了的Al液杂质更不容易通过,停滞于内浇口附近。敲掉料饼后,在内浇口处呈现黑色孔洞,其内壁粗糙,表面有明显油污。检查浇口和料饼夹渣情况,同样发现此类杂质。
Each casting cycle needs to add lubricating oil to the punch. The punch oil does not burn completely after pouring in the Al liquid, and is wrapped in the Al liquid to form impurities and fill the mold cavity together. Because of the low temperature of Al liquid coated with punch oil, it will solidify earlier and flow slowly, so it will stay at the end of the product at the end of filling. In addition, the cross-sectional area of the ingate is small and the flow resistance is large, which makes it difficult for the Al liquid impurities wrapped with punch oil and solidified in advance to pass through and stagnate near the ingate. After knocking out the cake, there are black holes in the inner gate, with rough inner wall and obvious oil stains on the surface. This kind of impurity was also found by checking the slag inclusion in the gate and cake.
冷硬层是指被注入到料筒内的Al液与料筒低温表面接触急速冷凝所形成的壳体(光谱仪检查冷硬层化学成分未发现异常,均在标准允许范围内),在高速填充时随Al液一起被填充到型腔。固态的冷硬层密度(2.7g/cm?)比液态(2.45g/cm?)的Al液大,在冲头低速运行阶段,冷硬层慢慢聚集在Al液的末端。冲头高速运行时,部分冷硬层将被卷入型腔,形成缺陷。终残留在内浇口的冷硬层形态。冷硬层多为薄片状,表面有光泽且较硬,与周围母材多存在间隙,不仅影响外观,也降低铝合金压铸件的强度。
The cold hard layer refers to the shell formed by the rapid condensation of the liquid Al injected into the barrel and the low temperature surface of the barrel (no abnormality is found in the chemical composition of the cold hard layer by the spectrometer, which is within the allowable range of the standard). It is filled into the cavity together with the liquid Al during the high-speed filling. The density of cold hard layer in solid state (2.7g / cm?) Specific liquid (2.45G / cm?) During the low speed operation of the punch, the cold and hard layer slowly accumulates at the end of the liquid al. When the punch runs at high speed, part of the cold hard layer will be drawn into the cavity, forming defects. Finally, the morphology of the cold and hard layer in the inner gate remains. The cold hardening layer is mostly thin sheet, with glossy and hard surface, and there are many gaps with the surrounding base metal, which not only affect the appearance, but also reduce the strength of aluminum alloy die casting.
总结现有生产条件的不足及与夹渣的关联性,从而制定相应的改善措施,保证合适的beplay全站app安卓温度,纠正错误的冲头润滑油供给方式,实现铝合金熔炼的标准化,并验证效果,使夹渣问题得到有效控制。
This paper summarizes the deficiency of existing production conditions and the relevance with slag inclusion, so as to formulate corresponding improvement measures, ensure the appropriate mold temperature, correct the wrong punch lubricating oil supply mode, realize the standardization of aluminum alloy smelting, verify the effect, and effectively control the slag inclusion problem.
氧化夹渣的防止方法:
Methods to prevent oxidation slag inclusion:
1.从冒口补浇金属液,改进冒口设计
1. Pouring liquid metal from riser to improve riser design
2.炉料应清洁无腐蚀
2. The furnace charge shall be clean without corrosion
3.铸件缩松处设置冒口,安放冷铁或冷铁与冒口联用
3. Riser is set at the shrinkage porosity of casting, and chill is placed or combined with riser
4.控制型砂水分,和砂芯干燥
4. Control the moisture of molding sand and dry the sand core
5.采取细化品粒的措施
5. Take measures to refine the grain size
6.改进铸件在铸型中的位置降低浇注温度和浇注速度
6. Improve the position of the casting in the mold and reduce the pouring temperature and pouring speed
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