Save Excel File to Textdocument

uses ExtCtrls, ComObj

//

function ExcelSaveAsText(ExcelFile, TextFile: TFileName): Boolean;
const
  xlText = -4158;
var
  ExcelApp: OleVariant;
  vTemp1, vTemp2, vTemp3: OLEVariant;
begin
  Result := False;
  try
    ExcelApp := CreateOleObject('Excel.Application');
  except
    // Error occured...
    Exit;
  end;
  try
    ExcelApp.Workbooks.Open(ExcelFile);
    ExcelApp.DisplayAlerts := False;
    vTemp3 := False;
    vTemp2 := xlText;
    vTemp1 := TextFile;
    ExcelApp.ActiveWorkbook.SaveAs(vTemp1, vTemp2, vTemp3);
    Result := True;
  finally
    ExcelApp.Quit;
    ExcelApp := Unassigned;
  end;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  if OpenDialog1.Execute then begin
    try
    ExcelSaveAsText(OpenDialog1.FileName,       // Excel Datei
                    OpenDialog1.FileName + '.txt');  // Textdokument
    except
    ShowMessage('Error');
    end;
  end;
end;