How are the fit tolerances for rings and grooves determined?
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This post was last edited by Slay demons and evil forces on 2019-2-27 08:51. As shown in the image, a groove needs to be made in a partition, with a metal ring placed inside that groove. An elastic gasket is installed on the left side of the metal ring for sealing; the thickness of the gasket is 3 mm, with a tolerance of ±0.2 mm. A gap must be maintained on the right side, with this gap ranging from 0.5 to 1 mm – this requirement must be strictly adhered to, as it is used for pouring sealant. The problem now is that it is necessary to ensure that the metal ring can be inserted, while at the same time ensuring that the gasket and sealant can also be inserted. What should be the tolerances for the inner and outer diameters of the groove? What are the inner and outer diameters of the metal ring, as well as their tolerances? I looked at the limits and fits for shafts and holes as taught in university, and it seems like they’re not the same thing!
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I’ll ask for you; I’m not too sure about this either.
This definitely isn’t made according to tolerances; the ring is formed by welding rolled sheet metal, so the errors are quite large. Personal opinion: The outer diameter of the ring should be 1018 – 3*2 = 1012; the thickness is 30. The outer diameter of the groove is 1012 + 3.5*2 + 3 = 1021, while the inner diameter of 949 will suffice. Please let me know the final dimensions you plan to use for processing, so that everyone can verify them.
The ring is forged. If no tolerance is specified, a gap of 0.5–1 cannot be guaranteed. The actual deviation in the processed products is likely to be around 1.5. But if it’s a mark, how should it be marked?
There was a misunderstanding – it’s not welding; it’s too thick. For forged parts, they need to be processed on a lathe and have their edges chamfered, and the size of the rings should be guaranteed. You can check the tolerance of the ring and then determine the groove error.
It’s hard to say. The key issue is that the groove has two surfaces, an inner one and an outer one, and both have deviations – so how do we determine the value?