product news/產品新聞
ship quickly even if the model is not in stock,” Vrielink said. Te development engineer also said he sees a significant
advantage in the higher quality. Te 3-D printed product corresponds one-to-one with the computer model, while hand-crafted products can result in small variances. More complicated pump wheel shapes yield higher savings when using this production process. A good example is the screw- centrifugal wheel, a tapered wheel that must correspond ex- actly with the model. Te shape of the wheel must be precise to avoid imbalances. Nevertheless, the pump manufacturer must often polish the castings afterward to remove any existing imbalances. Occasionally, castings must be polished for more than one day at the chip removal department. Sand printing takes care of the imbalances during the draft phase in the computer. Te casting is more precise and requires less follow-up work. “If the part is more complex, sand printing represents
an attractive alternative, certainly for prototypes, individual pieces or small series,” Vrielink said. At the Nijhuis pump factory, the castings produced with sand molds from voxeljet are extensively tested on a separate test stand. But Vrielink is convinced of their quality. “By using this technology, foundries can significantly
improve their competitive situation,” he said. ■ Visit
www.voxeljet.com for more information.
eljet生产大型的砂型，这也就意味着即使我们库中没有 相应的模样，也可以迅速生产并交付铸件。” 研发工程师表示这项技术还保证了铸件的高质量。3D 打印生产出的砂型和计算机模型完全匹配，而手工制作 的模型就会有些许的差异。泵轮的结构越复杂，采用3D 技术就可以节省越多的成本。一个很好的例子就是螺旋 式离心机的泵轮，这种泵轮是一种锥形砂轮，需要和模 型严格匹配避免出现不平衡的现象。然而，泵的生产商 往往需要不断地打磨铸件，这样才能消除已有的不平 衡。有的时候铸件还需要后续打磨，这要花费超过一天 的时间。3D砂型打印技术避免了在计算机设计图时产生 的不平衡。铸件更加精确而且后续的处理越来越少。 Vrielink表示：“如果工件越复杂，砂型打印技术就 越是必不可少，不只是对于原型生产，对于一些单批量 或者小批量的零件也是相当有用的。” 在Nijhuis的泵工厂，使用Voxeljet生产出的砂型浇 注出的铸件需要在独立的测试台上经过大量测试。但是 Vrielink从不担心铸件的质量。
他说：“通过使用这项技术，欧洲的铸造厂会在竞争 中处于优势地位。” ■ 获取更多信息请访问
www.voxeljet.com
Maintaining Shot Blasting Machines 抛丸机的保养
Wear and tear is an important aspect of shot blasting ma-
chines. As machine downtime is costly, it must be reduced to a minimum. While the material of the wear parts has great influence on service life, facilities can save shot blasting costs in other ways. Te effect of impurities and fines in
the abrasive often is underestimated. One rule of thumb is that smaller particles are more aggressive. Wear in shot blasting machines increases immensely with a growing fraction of fine particles. Sepa- rating any undersize particle (i.e. too fine abrasives, impurities and dust) out of the abrasive is important. In the case of shot blasting machines
used in foundries, the coarse parts must be discharged via a sieving conveyor for disposal. Te sieving conveyor is located below the blasting chamber. In order to purify the abrasive, an additional purifying
磨损和破裂是抛丸机的关键问题。机器停工成本很 高，因此必须将停工期降低到最低水平。磨损件的材料 对机器服役期有很大影响，但依然可以通过其它方式来 降低抛丸机的成本。
磨料中的杂质和碎屑的影响经常被 低估，一个原则是粒子越小，危害性 越大。微粒比例增加时，抛丸机的磨 损急剧增加。因此，将尺寸过小的微 粒，也就是细磨料、杂质和灰尘清除 出磨料非常重要。
当抛丸机在铸造厂中使用时，粗大 的部分必须通过过滤装置滤掉。过滤
Shown is a cross section of the magnetic separator and windsifter (red and yellow represent sand, blue is abrasive material.
所示为磁选机和风筛的交叉单元（红黄色 为砂，蓝色为磨料）.
Winter 2012
FOUNDRY-PLANET.COM | MODERN CASTING | CHINA FOUNDRY ASSOCIATION | 59
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