Law Enforcement officers in Plymouth Township have the dragnet out for two armed bank robbers.   The bandits held up the T-D bank branch on Germantown Pike Friday morning.   Investigators say one of them had two semi-automatic handguns.   The other kept a gun in his waistband.   The suspects demanded money and bank tellers put an undisclosed amount of cash in a drawstring bag for them.   The robbers fled and crossed Germantown Pike where a blue minivan was waiting for them.  It sped away eastbound on Germantown Pike.