Regarding the feed thickness and nominal thickness of the head
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For the head EHA 2470 *10(8.5), I understand that the 10 refers to the nominal thickness, but some people also consider it as the material thickness. Is this interpretation correct? 1. What is the relationship between the feed thickness and the nominal thickness? 2. How is nominal thickness applied? 3. Is there a formula for the feeding thickness? Explain in detail.
The feeding thickness is appropriate, as the airflow pressure causes thinning
The feeding thickness is that used by the head manufacturing plant; the nominal thickness is specified by the design agency or the container manufacturer. Sometimes, to ensure that the thickness after processing remains at least as large as the nominal value, the feeding thickness needs to be a bit larger. However, now it’s indicated in parentheses, so it seems easier to handle – using 10 should suffice. During inspection, a value greater than 8.5 is sufficient
Here, 10 mm is the nominal thickness; the 8.5 mm in parentheses represents the minimum thickness that must be maintained after deducting the difference between the head shape and the thickness of the steel plate, as well as the thinning that occurs due to stamping of the head. The forming thinning rate for end caps under the corresponding specifications can be found in the JB4746 end cap standard; it is necessary to ensure that the value within the parentheses is greater than the minimum thickness calculated in the calculations. If there is a corrosion allowance, it must be ensured that 8.5 is greater than the minimum thickness plus the corrosion allowance. The thickness of the material used, as you mentioned, has nothing to do with the design; it is determined by the equipment manufacturer when creating the manufacturing process sheets. Based on the manufacturer’s processing capabilities, they estimate the appropriate thickness for the seal so that the thinnest part of the seal, after the equipment has been manufactured, will have a thickness of at least 8.5. It can be seen that a minimum thickness of 8.5 mm must be ensured; therefore, 10 mm can certainly be used as the feeding thickness, but it is not the only possible value for the feeding thickness.
Agree with what was said on floor 4: 10mm is the nominal thickness at design time, while 8.5mm is the minimum thickness achievable during manufacturing； In other words, no matter what thickness the manufacturer uses for the material, it must be at least 8.5 mm.
“If there is a corrosion allowance, it must be ensured that 8.5 is greater than the minimum thickness plus the corrosion allowance. ”Is there a mistake in this sentence? ! This 8.5 should include the corrosion allowance and the negative thickness deviation, right?