Due to the limited conditions, two methods can be used to identify the processed tin bronze workpieces simply. One is to observe the color of the workpiece, that is, the color of the processed workpiece changes from the original brass color to blue and black, and the workpiece is on the workpiece due to oxidation. An oxide layer of 2 ~ 3μm thick is formed on the surface, which is easy to fall off; second, the processed workpiece can be directly bent by hand to judge. When bending, if you feel that the workpiece can be bent while having a certain strength and elasticity, it means that the annealing effect is good and it is suitable for forming.
On the contrary, the treated workpiece has high strength and elasticity and is not easy to bend by hand, indicating that the annealing treatment effect is not good, and it needs to be re-annealed. In order to achieve the purpose of uniform temperature and anti-oxidation, tin bronze workpieces are generally not suitable for processing in a box furnace without a stirring fan. For example, under the condition of the same furnace load, the workpiece is compared in a box furnace without a stirring fan and a pit tempering furnace with a stirring fan.
Under the same annealing process conditions of heating at 350 ± 10 ℃, holding for 2 hours and then air cooling, the treatment results of the two are quite different. The workpieces processed in the box furnace have different brilliance, high strength and insufficient toughness, making it difficult to bend. However, after the pit tempering furnace is used to process the same batch of workpieces, the brilliance is more uniform, and the strength and toughness are appropriate, which is conducive to subsequent processing operations.
Therefore, for enterprises with limited conditions, annealing treatment can be handled by a pit furnace, and a larger capacity tempering barrel can be used for charging. It is better to have a large number of drilling holes on the tempering barrel wall to facilitate uniform heating of the workpiece, but it must be The workpiece must be placed neatly to avoid deformation of the bottom layer due to pressure.
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