Export Batch for Autocad DXF?

Hy!
Is there anywhere an export batch for autocad dxf to export all views in on step?
Or how i can start the autocad dxf inside a phyton?

When i execute the operator the export window will not pop up:



class NewDXF(bpy.types.Operator):
    """Export DXF"""
    bl_idname = "object.finish_dxf"
    bl_label = "Export DXF"

    @classmethod
    def poll(cls, context):
        return context.active_object is not None

    def execute(self, context):
        bpy.ops.object.join()
        bpy.ops.object.origin_set(type='ORIGIN_GEOMETRY')
        bpy.ops.object.location_clear()
        bpy.ops.export.dxf(filepath="", projectionThrough='NO', onlySelected=True, apply_modifiers=True, mesh_as='3DFACEs', entitylayer_from='obj.data.name', entitycolor_from='default_COLOR', entityltype_from='CONTINUOUS', layerName_from='LAYERNAME_DEF', verbose=False)
        return {'FINISHED'}