To examine the effect of clamping force on the inter-layer gap formed in stacked material drilling

firstly

the drilling deformation state of stacked plates with clamping force was analyzed using elastic shell theory. Further

by finite element method

the drilling deformation model with clamping force was established in consideration of interface contact condition. The accuracy of model was verified by comparing with experimental results of single-plate deformation. Then

the changing process of inter-layer gap was analyzed under different drilling conditions. At last

the experiment was carried out to verify the finite elements analysis results. The results show that

with the increase of clamping force

the inter-layer gap will go through two stages

decreasing rapidly at first and slowly after the turning point. The turning point corresponds to the critical clamping force. To obtain an effective burr height reducing

the following two conditions must be required: Ⅰ) the inter-layer gap DB corresponding to the turning point should be smaller than the drilling burr height without applying the clamping force

Ⅱ) the clamping force should be higher than the critical force FB. Besides

reducing the thrust force

or minimum diameter of the clamping ring can reduce the demand clamping force and inter-layer gap size. To enhance the effects of clamping force and minimize inter-layer gap

the thicker plate and the plate with higher modules should be set as the back plate.