timesheet formula

can someone please help me with this..

i have a timesheet that we are trying to use. the problem is the column that says shift diff. if an employee works after 6:30pm for 1and 1/2hr, he is entitled to shift hours. shift hours is between 6:pm and 8am. can you help me add the shift hours automatically in the shift diff column in excel.

As long as he works after 6.30pm but works for at least one and a half hour, he will get the shift.
if he comes to work at 9pm to 12am, then he gets 3hrs shift for those hours too.