I'm still pretty new to PyQT but I think you can do it like this -
def show_form2(self):
newDialog = uic.loadUi(r"uifile.ui")
newDialog.show()
or if you've subclassed it, make sure you import
it if it's in another file and use
def show_form2(self):
newDialog = subDialog.subDialog()
newDialog.show()
edit - oh and make sure you connect it to the buttons click
self.bt_form1.clicked.connect(self.show_form2)