US Patent: 2,169,159
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| Means for Accurate Screw Cutting
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Patentee:
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| Georg Müller (exact or similar names) - Berlin-Neukolln, Germany |
| Manufacturer: |
| Not known to have been produced |
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Patent Dates:
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| Applied: |
Jan. 13, 1939 |
| Granted: |
Aug. 08, 1939 |
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Joel Havens
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Description: |
| Application filed in Germany, 11 Jun 1938.
This invention relates to a thread cutting and grinding machine for the manufacture of threaded elements, such as bolts and the like. More particularly, the invention relates to an 5 improvement of the machine shown in U. S. Patent No. 2,125,584 granted to Erich Rotzoll. In the patent to Rotzoll, there is provided a guide block for the tool or workpiece which is actuated by means of a guide thread spindle, a supplemental movement being given to said guide block for correcting the variations of the block movement, this supplemental movement being controlled by means of a light sensitized device. In the adjustment device of Rotzoll, a master thread spindle is mounted parallel with the threaded guide spindle controlling the cutting operation of the machine, and this rotation is adjusted in such manner that an imaginary point on the thread of the master spindle moves forward during each rotation the same distance as the block and which, when variation occurs between the forward movement of the guide block and the pitch of the master spindle, brings into action a light sensitive electric cell which actuates an electro-magnetic device for correcting the variation of the pitch. In the present invention, instead of providing a master spindle running parallel to the guide spindle of the machine, there is provided a cylindrical longitudinal scale having spiral lines thereon and these lines are reflected by optical means on a diaphragm having an opening and a light sensitive cell is positioned behind this diaphragm so that variations in the thread on the guide spindle from the master thread causes an electromagnetic action for supplemental correction action of the feeding of the block. There is thus provided a highly accurate means for correcting longitudinal feed of screw cutting or grinding machines. An object of this invention is to employ cylindrical scales with spiral division lines for the purpose of correcting, by electrical means under control of a light sensitive cell, variations in the thread cutting or grinding of a thread cutting or grinding machine. A further feature of the invention is the employment of several optical systems with diaphragm and light sensitive cells reflecting light beams from the spiral division line of the longitudinal scales, these optical systems being mounted in such manner that in one system the scale division lies to the left of the opening of the diaphragm, while in the other system the scale division line lies to the right of the diaphragm, whereby any variation to the right or left will be immediately detected and corrected. The principal object of the invention is to provide a light sensitive means for accurately cutting or grinding threads on a rotating blank. |
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