What are the patents of the three-layer steel knurling machine?

Three-layer steel knurling mechanism, steel plate knurling machine and its use method, three-layer steel plate knurling technology.

1. The patents of the three-layer steel knurling machine include the three-layer steel knurling mechanism, the steel plate knurling machine and its use method, and the three-layer steel plate knurling technology.

2. Patent literally refers to exclusive rights and interests. The word "patent" comes from the Latin word Litteraepatentes, which means a public letter or public document.