Is it normal to have several horizontal stripes on the inner wall of the vacuum flask?

Since I travel a lot recently, I haven't read my friends' messages for a long time.Saw a message today while looking through the messages and getting ready to reply.The original text is as follows: After opening the newly purchased thermos cup, I found that there are many horizontal lines on the wall of the cup. Is this phenomenon normal?Will it affect usage?Is it a defective water cup that can apply to the merchant for return? Is it normal to have several horizontal stripes on the inner wall of the vacuum flask?

The moment I saw the question, I understood what my friend meant.However, in order to avoid the narrow meaning of the editor's understanding, I still ask the other party to send a picture to take a look by replying to the other party.After seeing it, I confirmed that my understanding was correct.The following editor will explain to you why some water cups have a horizontal line of one week in the inner tank, some have several lines, and some have only one or two lines.

The editor mentioned in the previous article that the liner of the stainless steel thermos cup is currently welded by water swelling and stretching through the methods that various manufacturers will adopt.There will be an obvious annular corrugated line inside the water cup, indicating that this water cup adopts the stretching process.What is the stretching process, generally speaking, the stamping process is believed to be known by many friends.The stretching process can be understood as a stamping process that does not stamp out the bottom.By stretching, a steel sheet can be gradually pulled higher and higher until it can meet the needs of the inner tank size.

Since the diameter of the water cup is not large, but the height is different, the stretching process cannot meet the needs of being able to stretch in place at one time, because the stretching of excessive strength will directly break the steel sheet.In order to meet the needs of the next production process, a water glass liner usually needs to be stretched 3-5 times or even more.Then every time the stretch cannot be perfectly fitted, a looped stretch line will appear, but it does not mean that the stretched water cup must have a stretch line.Stretch lines can be eliminated by improving the process or adding a process.

First of all, the more precise the mold development, the thinner the stretch line will be.Secondly, the replacement of the good stretch can also improve the production quality.The editor has seen many stretched water cups with almost no stretch lines.

There is another way, which has been very popular in the market, to spin the inside of the water cup again through the spinning thinning process.After this treatment, the stretch line is completely invisible.This phenomenon can also be alleviated by electrolysis or polishing, but the effect is relatively general, and it is not as thorough as spinning thin.

There are many obvious stretching lines inside the water cup. It can only be said that the production process is not exquisite enough during production.This situation will make the performance of the water cup not beautiful enough, but it cannot be said that this is a water cup that cannot be used unqualified.If you want to refund with the merchant, what is the standard of the merchant?There is no rigid rule in the water cup industry that such a water cup is a defective product.