关闭PyQt对话框而不关闭主程序

我正在尝试使用在Qt Designer中创建的PyQt对话框来接受一些用户输入(复杂性评级、材料类型和机器类型(，然后使用这些输入来提醒我的python程序。对话框中显示的选项是从字典中读出的。我的问题是，无论我尝试了什么，通过按下提交按钮关闭对话框，都会停止程序的其余部分运行，无论我是将对话框保留在主py程序中，还是将其作为一个函数在单独的文件中运行。我很确定它与sys.exit(app.exec_())行有关，我也尝试过使用.close和.rejecte来关闭对话框，结果相同。此外，我知道这个程序不太好，我正在处理函数中传递的变量，但如果你对如何让我的程序的其余部分与对话框对话有任何建议，我将不胜感激，我已经在这个问题上耗尽了谷歌的其余部分，非常感谢！

import os
import numpy as np
def get_part_info():
material_ops =[]
complex_ops = [1,2,3]
machine_ops = []

#---Dictionary containing material options and machine options is read out here, this part works fine ----

mat_choice = 'empty'
comp_choice = 'empty'
mach_choice = 'empty'

from PyQt5 import QtCore, QtGui, QtWidgets
class Ui_Dialog(object):
def setupUi(self, Dialog):
Dialog.setObjectName("Dialog")
Dialog.resize(227, 217)
self.verticalLayout_3 = QtWidgets.QVBoxLayout(Dialog)
self.verticalLayout_3.setObjectName("verticalLayout_3")
self.verticalLayout = QtWidgets.QVBoxLayout()
self.verticalLayout.setObjectName("verticalLayout")
self.Material = QtWidgets.QComboBox(Dialog)
self.Material.setObjectName("Material")
self.verticalLayout.addWidget(self.Material)
self.Complexity = QtWidgets.QComboBox(Dialog)
self.Complexity.setObjectName("Complexity")
self.verticalLayout.addWidget(self.Complexity)
self.Machine = QtWidgets.QComboBox(Dialog)
self.Machine.setObjectName("Machine")
self.verticalLayout.addWidget(self.Machine)
self.textEdit = QtWidgets.QTextEdit(Dialog)
self.textEdit.setObjectName("textEdit")
self.verticalLayout.addWidget(self.textEdit)
self.verticalLayout_3.addLayout(self.verticalLayout)
self.Submit = QtWidgets.QPushButton(Dialog)
self.Submit.setMaximumSize(QtCore.QSize(100, 16777215))
self.Submit.setObjectName("Submit")
self.verticalLayout_3.addWidget(self.Submit, 0, QtCore.Qt.AlignHCenter|QtCore.Qt.AlignVCenter)
#------Read out from the dictionary is added to the drop down menus here-----
for i in list(material_ops):
self.Material.addItem(i)
for i in list(complex_ops):
self.Complexity.addItem(str(i))
for i in list(machine_ops):
self.Machine.addItem(i)

self.Submit.pressed.connect(self.save)
self.retranslateUi(Dialog)
self.Submit.pressed.connect(Dialog.reject)
QtCore.QMetaObject.connectSlotsByName(Dialog)

def retranslateUi(self, Dialog):
_translate = QtCore.QCoreApplication.translate
Dialog.setWindowTitle(_translate("Dialog", "Dialog"))
self.Submit.setText(_translate("Dialog", "Submit"))

def save(self):
global mat_choice, comp_choice, mach_choice
mat_choice = (self.Material.currentText())
comp_choice = (self.Complexity.currentText())
mach_choice = (self.Machine.currentText())

if __name__ == "__main__":
import sys
app = QtWidgets.QApplication(sys.argv)
Dialog = QtWidgets.QDialog()
ui = Ui_Dialog()
ui.setupUi(Dialog)
Dialog.show() 
sys.exit(app.exec_())
return mat_choice, comp_choice, mach_choice, matdict

get_part_info()
print('Rest of programme is working') # programme never gets this far
#---The rest of the programme that uses these user chosen options is here and never runs due to the dialog closing stopping the whole programme ------