Ejemplo para la pregunta https://es.stackoverflow.com/questions/120117/

main.py

import sys
import time
from PyQt5.QtCore import *
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *

class Delegado(QAbstractItemDelegate):
    def __init__(self):
        super(Delegado, self).__init__()

    def paint(self, painter, option, index):
        estilo = "QProgressBar#barraDelegado{border: 0px solidgrey; border-radius: 5px; text-align: center; color: grey; font-weight: bold;} "
        estilo += "QProgressBar#barraDelegado::chunk {background-color: #CD96CD;}"
        #f = open("../css/estilos.css")

        barra = QProgressBar()
        barra.setObjectName("barraDelegado")
        value = index.data()
        barra.resize(option.rect.size())
        barra.setMinimum(0)
        barra.setMaximum(100)
        barra.setAlignment(Qt.AlignCenter)
        print(value)
        barra.setValue(int(value))
        if barra.value() < 51:
            barra.setStyleSheet(estilo)
        elif barra.value() > 50 and barra.value() < 100:
            barra.setStyleSheet("QProgressBar#barraDelegado{font-weight: bold; border: 0px solidgrey; border-radius: 5px; text-align: center; color: white} QProgressBar#barraDelegado::chunk {background-color: orange; color:red;}")
        elif barra.value() > 99:
            barra.setStyleSheet("QProgressBar#barraDelegado{font-weight: bold; border: 0px solidgrey; border-radius: 5px; text-align: center; color: white} QProgressBar#barraDelegado::chunk {background-color: lightgreen; color:red;}")

        painter.save()
        painter.translate(option.rect.topLeft())
        barra.render(painter)
        painter.restore()
        #f.close()

    def createEditor(self, parent, option, index):
        self.slider = QSlider(parent)
        self.slider.setAutoFillBackground(True)
        self.slider.setOrientation(Qt.Horizontal)
        # slider.installEventFilter(self)
        self.slider.setRange(0, 100)
        #print("return slider")

        self.slider.valueChanged.connect(self.imprime)
        return self.slider

    def updateEditorGeometry(self, editor, option, index):
        editor.setGeometry(option.rect)
        print("update geometry")

    def setEditorData(self, editor, index):
        #print("editor data")
        #value = index.model().data(index, Qt.DisplayRole)
        editor.setValue(int(index.data()))


    def setModelData(self, widget, model, index):
        print("columna: {0} Fila: {1}".format(index.column(), index.row()))
        model.setData(model.index(index.row(), 1), str(widget.value()), Qt.DisplayRole)
        value = widget.value()
        widget.setToolTip(str(value))
        print(widget.value())
        #self.modelo.setData(self.modelo.index(0, 1), str(progress), Qt.DisplayRole)
    def imprime(self, valor):
        self.slider.setToolTip(str(valor))
        print(valor)

    def sizeHint(self, option, index):
        return QSize(200, 20)

class Hilo(QThread):
    def __init__(self, modelo, *args, **kwargs):
        QThread.__init__(self, *args, **kwargs)
        self.modelo = modelo

    def __del__(self):
        print("Fruncion __del__")
        self.wait()

    def run(self):
        for i in range(0, 100):
            time.sleep(0.3)  # artificial time delay
            import random 
            row = random.randint(0, self.modelo.rowCount()-1)
            ix = self.modelo.index(row, 1)
            QMetaObject.invokeMethod(self.modelo,
                "setData", Qt.QueuedConnection, 
                Q_ARG(QModelIndex, ix), 
                Q_ARG(QVariant, str(i)))
            print("ejemplo {0}".format(i))

class Window(QWidget):
    def __init__(self, *args, **kwargs):
        QWidget.__init__(self, *args, **kwargs)
        self.setLayout(QVBoxLayout())
        obj = QTableView(self)
        model = QStandardItemModel()
        model.setColumnCount(3)
        items = [("0", "0", "4") , ("0", "0", "2"), ("0", "0", "2")]
        for item in items:
            it = [QStandardItem(i) for i in item]
            model.appendRow(it)
        obj.setModel(model)
        obj.setItemDelegateForColumn(1, Delegado())
        self.layout().addWidget(obj)
        hilo = Hilo(model, self)
        hilo.start()

def main():
    app = QApplication(sys.argv)
    w = Window()
    w.show()
    sys.exit(app.exec_())

if __name__ == "__main__":
    main()