Head thinning rate
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How should the thinning rate for end caps with a thickness of less than 6 mm be determined? For example, when manufacturing a head of size EHA400*4, what should be the thickness of the steel plate used? In GB/T25198, the starting thickness is 6 mm.
A 6mm plate will suffice; the drawing specifies a head thickness of 6/(tmin=4).
Mm. What is the thinning rate? Because there are also sizes such as 1.5mm and 3mm.
This needs to be asked of the head manufacturing factory; the rate of thinning varies depending on the forming process, and there are also differences among different head manufacturers.
The appendix to the head standards provides recommended values for the degree of thinning during forming. For heads of the same diameter, the smaller the thickness, the greater the degree of thinning; as a reference, it is acceptable for a 5mm thick plate to be reduced to 4mm after forming.
First, the minimum forming thickness must meet the strength requirements. If the thinning rate is unknown, use min5.7 directly
The recommended values for the deformation thinning rate in the head standard are too conservative
The main reason is that most container plates these days have a positive deviation.
For elliptical heads, I usually apply a factor of 10%; I’ve heard that some head manufacturers use a factor of 8%. This factor needs to be determined based on the type of head, the material used, the thickness, and the manufacturing process. It’s best to consult with the head manufacturer. For a 6mm thick plate with a negative deviation of 0.3mm, the thickness of the head will be (6 – 0.3) * 0.9 = 5.13mm; rounding this value gives 5.1mm