输出文字到word的程序报错！

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  输出文字到word的程序，但是当多个CAD同时运行此函数时会报错，估计是同时调用WORD的问题，应该怎样修改呢？
(setq wrd_app (vlax-get-or-create-object "Word.Application"))
  (vla-put-visible wrd_app :vlax-true)
  (vlax-put-property wrd_app 'ScreenUpdating :vlax-false)
  (setq wrd_docs (vlax-get-property wrd_app 'Documents))
  (vlax-invoke-method wrd_docs 'Open doc_name :vlax-false)
  (setq wrd_doc (vlax-get-property wrd_app 'Activedocument))
  (vlax-invoke-method wrd_doc 'Activate)
  (write_to_end wrd_app txt1)
  (vlax-put-property wrd_app 'ScreenUpdating :vlax-true)
  (vlax-invoke-method wrd_doc 'Saveas doc_name)
  (vlax-invoke-method wrd_doc 'Close)