Figure 2. This is a 70-metric- ton core made with Bangni resin sand.
图2 用邦尼树脂砂制成的 重70吨的砂芯
when reclaiming alkaline phenol resin sand are not yet included.
Service Performance of Bangni Resin Second hardening characteristics—Bangni resin is a
type of modified resole phenolic resin, with which the pre- pared molding sand has second-hardening characteristics. During production, after coating with an alcohol-based coating, the coating is fired and the strength and surface stability of molds and cores are improved significantly. Compared to water glass and alkaline phenolic resin
sand, Bangni resin sand has remarkable features: after stripping from the pattern, the molds have a relatively high initial strength, which is beneficial for both strip- ping and subsequent handling; and the residual strength after pouring is not too high, which is good for shakeout and reclamation. The final mold strength is around 0.5MPa, but
because of the second hardening process, no castings are scrapped due to weak sand strength. For Wuxi Foundry production, the sand strength after 24 hours is controlled at 0.5 - 0.7MPa. When Tian Qian Heavy Industries Holdings Co. Ltd
produced a 160-metric-ton steel casting, the strength of Bangni resin sand totally satisfied the requirements of the casting process, especially when the large core, weighing 70 metric tons was lifted; the core was strong and without any signs of cracking (Fig. 2). Sand strength in the ‘plum rain’ season in South
China—During the plum rain season, with a humidity of 98%, Bangni resin still has a satisfactory hardening rate and initial strength, overcoming the problem with water glass sand, which absorbs moisture and results in a slow hardening rate.
左右。
其中，还未计及碱酚醛树脂砂热法再生设备的投 资、运行费用和相关的折旧费用。
4、邦尼树脂的使用性能 （1）具有二次硬化的特性
邦尼树脂是一种改性的甲阶酚醛树脂，用以配制的 型砂具有二次硬化特性。生产过程中，铸型涂醇基涂 料并点燃后，砂型、芯子的强度与表面稳定性都有较 大的改善。
邦尼树脂砂与水玻璃砂、碱性酚醛树脂砂相比， 在生产中有一个突出的特点，即：砂型起模后初始强 度较高，有利于起模、搬运；浇注后的残留强度并不 高，有利于落砂与砂再生。
由于邦尼树脂有二次硬化过程，即使试样的终强度
在0.5MPa左右，在生产中也从未发生因型砂强度不 够而产生的废品。无锡铸造厂生产中，型砂试样放置 24h后的强度基本上控制在0.5—0.7MPa的范围内。 天乾公司生产160吨的铸钢件时，邦尼树脂砂的强 度完全满足了工艺要求，尤其在吊起70吨的大型砂芯 时，强度很好，无任何裂纹，见图2。
（2）在南方梅雨季节时的型砂强度 邦尼树脂，在湿度高达98%的梅雨季节，仍保持
Figure 3. Large pieces of molding sand fell off the castings during shakeout.
图3 脱箱后铸钢件表面型 砂的大片脱落的情况
February 2013
FOUNDRY-PLANET.COM | MODERN CASTING | CHINA FOUNDRY ASSOCIATION | 47
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