How to design a self-lock structure ?

　　This is a suitcase that we can often see in our life. The bottom is a automatic lock structure, this self-lock structure is different from the semi-automatic end lock structure, is more complicated. On the top of the self-lock structure it is a portable and no need to punch line.

　　When design this self-lock structure should pay attention to the following points:

The upper hand-carrying hole length SW2, generally can not be more than half the length L, namely SW2 < L / 2;
W5 is half width W minus half of paper’s thickness: W5 = W / 2 - CAL / 2;
H6 is half length L minus paper thickness: H6 = L / 2 - CAL;
H7 is half width W: H7 = W / 2;
K6 is half width W: K6 = W / 2;
General K8 can not be more than W / 4;

　　The most important is:
SW1 is slightly larger than the distance above the red arrow, the measured value of 29.15, it can be SW1 take 31: SW1 = 31.

After molding, for 3D graphic:

　　Attachment: 
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