The main points of pre-stretching inspection and quality control of alloy aluminum plate are:
1 Plates shall be stretched in batches and the markings shall be clear, complete and consistent with the production card.
2 The unevenness of the chassis on which the stretched sheet is placed is not more than 30 mm.
3 The gage used for the test shall meet the requirements and be within the effective inspection period.
4 In order to accurately control and measure the amount of stretch, draw the measurement line on the board before pre-stretching.
5 After stretching, mark the measured tensile amount at different marking positions to prevent the sheet from being over-sized after stretching. Vertical and horizontal unevenness of sheet thickness.
6 Measure the thickness of the sheet before and after stretching, accurately control the amount of stretch, and prevent the aluminum sheet from being oversized after stretching. When the thickness of the sheet is not more than 25mm, it should be stretched and then stretched.
7 When there is fission at the edge of the aluminum sheet, it must be stretched by the sawing machine and the width tolerance of the sawing edge is controlled by +10mm.
8 Stretch the upper piece to be aligned with the center line, and the length of the jaws of the aluminum plate extending into the end of the stretching machine should be controlled evenly. The actual thickness of the aluminum sheet is generally controlled at 2.5% and the local area is not more than 3%.
9 The amount of stretch indicated by the meter shall be stretched by 0.5%-0.8% more than the actually controlled amount of stretch, and the amount of stretch shall be increased or decreased within this range depending on the time interval from quenching to stretching.
10 After quenching, the hard aluminum alloy should not exceed 4H, and the super-hard aluminum alloy should not exceed 6H. The aluminum sheet exceeding the time is not allowed to stretch, but it is allowed to be stretched after re-quenching.
11 The amount of stretch required for aluminum sheets can only be drawn at one time, and secondary stretching is not allowed.
12 For plates that have been artificially aged, the board should be covered with cardboard after stretching, and placed on a flat floor mat.
13 After surface stretching, the surface quality and geometrical dimensions of the finished sheet should meet the requirements of the corresponding product standards and mark the product.
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