Apparatus and process for removing a predetermined portion of reflective material from mirror

Apparatus for accurately cutting a stripe in a reflective coating on the surface of a mirror, said apparatus comprising:

• a) mirror holding means capable of receiving a mirror and maintaining a mirror surface having a reflective coating thereon in a plane parallel to a first surface on said mirror holding means;
• b) a top plate having first and second spaced apart parallel surfaces, said first surface of said top plate being mounted to said first surface of said mirror holding means to form a substantially enclosed housing;
• c) rail mounting means on said second surface of said top plate for mounting a pair of rails parallel to one another and in a plane parallel to and spaced from said second surface of said top plate;
• d) a movable carriage mounted on said rails to move over said second surface of said top plate in a plane parallel to said second surface and in a direction parallel to the axes of said parallel rails, said movable carriage provided with spaced apart ball bushings at opposite ends of said carriage to receive said rails, whereby the travel of said carriage along said rails is maintained in a direction parallel to the plane defined by said parallel rails and parallel to the plane of said reflective coating on said surface of said mirror to thereby permit accurate cutting of a straight stripe of said reflective coating from the surface of said mirror;
• e) rotatable cutting blade retaining means on said carriage capable of rotating in a plane normal to the second surface of said top plate and parallel to the axes of said rails;
• f) a cutting blade mounted on said rotatable cutting blade retaining means and having a cutting edge thereon disposed transverse to the longitudinal length of the stripe to be cut in said reflective coating and an included angle at the tip of said blade of from about 60.degree. to about 80.degree.;
• and
• g) means for rotating said rotatable cutting blade retaining means and said cutting blade mounted thereon into engagement with said reflective coating on said mirror in said mirror holding means at a fixed angle between said plane of said reflective coating and a side tip surface of said cutting blade of less than about 15.degree.;
• whereby movement of said carriage along said rails while said cutting blade is in contact with said reflective coating results in a stripe being accurately cut in said reflective coating equal to the width of said cutting blade.

Apparatus for accurately cutting a stripe in a reflective coating on the surface of a mirror, said apparatus comprising:

• a) mirror holding means capable of receiving a mirror and maintaining a reflective coating surface thereon in a plane parallel to a first surface on said mirror holding means;
• b) a top plate having first and second spaced apart parallel surfaces, said first surface of said top plate being mounted to said first surface of said mirror holding means, to form a substantially enclosed housing;
• c) rail mounting means on said second surface of said top plate for mounting a pair of rails parallel to one another and in a plane parallel to and spaced from said second surface of said top plate;
• d) a movable carriage mounted on said rails to move over said second surface in a plane parallel to said second surface of said top plate and in a direction parallel to the axes of said parallel rails;
• e) a central slot in said top plate extending from said first surface to said second surface of said top plate, said slot having a major axis parallel to said rails on said top plate, and having a length sufficient to permit a cutting blade to communicate with said reflective coating on said mirror surface from one edge of said mirror to the opposite edge as said carriage is moved over said slot;
• f) a cutting blade having an inclined angle at the tip thereof from about 65.degree. to 75.degree., said cutting blade being mounted on rotatable cutting blade means and having a cutting edge thereon disposed transverse to the longitudinal length of a stripe to be cut in said reflective coating;
• g) said rotatable cutting blade retaining means mounted on said carriage and capable of rotating in a plane normal to the second surface of said top plate and parallel to the axes of said rails comprising:
• i) a pair of parallel spaced apart mounting blocks secured to said movable carriage on opposite sides of said slot;
• ii) a rotatable shaft rotatably received adjacent opposite ends thereof in ball bearing races in respective bores in said mounting blocks normal to said major axis of said slot so that said shaft is disposed parallel to said plane defined by said rails and capable of rotating in a plane normal to said plane defined by said parallel rails;
• iii) cutting blade clamping means nonrotatably mounted on said shaft between said pair of mounting blocks, and having said cutting blade clamped thereto, so that rotation of said shaft and said cutting blade clamping means thereon toward said second surface of said top plate rotates said cutting blade through said slot toward said reflective coating on said mirror;
• h) means for rotating said rotatable cutting blade retaining means and said cutting blade mounted thereon into engagement with said reflective coating on said mirror in said mirror holding means at an angle of less than about 15.degree. between the plane of said reflective coating surface and the surface of said cutting blade facing said reflective coating;
• i) spaced apart ball bushings at opposite ends of said carriage to receive said rails, to provide for accurate travel of said carriage along said rails in a direction exactly parallel to the plane defined by said parallel rails and parallel to said major axis of said slot to thereby maintain said cutting edge of said blade accurately in a plane parallel to said plane of said reflective coating on said mirror to thereby cut a straight stripe of said reflective material from the surface of said mirror;
• whereby movement of said carriage along said rails while said cutting blade is in contact with said reflective coating results in a stripe being accurately cut in said reflective coating equal to the width of said cutting blade.