{
  "patent_number": "US 2820187",
  "country": "US",
  "title": "How Early Numerical Control Systems Automated Industrial Milling Machines",
  "original_title": "Motor controlled apparatus for positioning machine tool",
  "summary": "A 1952 invention by John Parsons that used punched cards to automatically guide machine tools, effectively launching the era of computer-aided manufacturing.",
  "what_it_does": "The system uses a motor-driven apparatus to control the position of a machine tool based on pre-recorded data. By reading instructions from a medium like punched cards, the system translates numerical coordinates into physical movements of the machine's cutting head. This allows for the precise, automated shaping of complex parts that would be difficult or impossible to produce manually. It essentially replaces the human operator's manual adjustments with a repeatable, machine-readable control loop.",
  "what_it_does_not_cover": [
    "Does not cover software-based CAD/CAM systems that design the parts themselves",
    "Does not cover modern CNC systems that use real-time sensor feedback for error correction",
    "Does not cover machines that operate without a motor-driven positioning mechanism",
    "Does not cover manual machine tools where the operator directly guides the cutting path"
  ],
  "filed": "1952-05-05",
  "granted": "1958-01-14",
  "expires": "1975-01-14",
  "status": "expired",
  "holder": "Parsons Corp",
  "holder_url": "https://patentbrief.org/company/parsons-corp",
  "inventors": [
    {
      "name": "John T Parsons",
      "url": "https://patentbrief.org/inventor/john-t-parsons"
    },
    {
      "name": "Frank L Stulen",
      "url": "https://patentbrief.org/inventor/frank-l-stulen"
    }
  ],
  "times_cited": 44,
  "tags": [
    "mechanical",
    "manufacturing",
    "aerospace",
    "automotive"
  ],
  "abstract": null,
  "url": "https://patentbrief.org/patent/us/2820187/numerical-control-machine-tool-parsons",
  "markdown_url": "https://patentbrief.org/patent/us/2820187/numerical-control-machine-tool-parsons/md",
  "google_patents_url": "https://patents.google.com/patent/US2820187",
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}