Patent GB-405480-A (GB)
Title: Improvements in or relating to machines for shaping work pieces by grinding, abrading or cutting
IPC: B24B3/18
Filed: 1933-03-31
Abstract: 405,480. Gauging-apparatus. CROSS, E. J., 10, New Court, Lincoln's Inn, London.- (Dardelet Threadlock Corporation; 120, Broadway, New York, U.S.A.) March 31, 1933, No. 9760. [Class 106 (ii).] A machine for shaping work by means of a grinding, abrading or cutting tool is provided with a means for gauging and testing the work comprising a comparator device including a microscope adapted for observing the work, and having a comparing mark in visual register with the eyepiece for comparison of the work with the mark through the microscope during the shaping operation on the work. As applied to grinding the crests C of the threads of a tap for forming Dardelet threads, the machine consists of a bed 1 carrying on a pedestal a grinding wheel 2, and carrying also a carriage 7 adjustable towards and from the grinding wheel by a screw 47. The carriage has slidable thereon, parallel to the axis of the wheel 2, a slide 10, and on the slide is mounted an upper slide 9 carrying a chuck 5 and tailstock 6 for the tap T. The chuck is driven through gearing 12-28, including a clutch 29, 29a from an electric motor M, which also drives the grinding wheel 2 by a belt B. The grinding wheel spindle is mounted eccentrically in a drum 33 rockable in the pedestal 4 by an arm 35, which carries a pin 37 contacting with a cam 36 having rises 38, and driven at such speed that as each land is ground, the wheel is rocked away from the tap whilst this rotates to bring a new land into grinding position. The tap is moved axially, corresponding with the pitch of the thread, by a face cam 40 driven at the same speed as the work and acting in conjunction with a spring through a tappet arm 42 to move the slide 10. The carriage 7 has thereon a base 45 on which is mounted a slide 50 movable parallel to the work axis by a screw 84, and on a portion 54 of the slide 50 is a vertical post 55 bearing a barrel 56 movable by a micrometer screw and head 64, and in an ear 72 on the barrel is mounted a bar 73 on which is slidable a barrel 74 adjustable to and from the work by a screw 75. The barrel carries the microscope in an extension 76 and is guided by the contact of a pin 81 on an arm 80 on the barrel with a track 79 on an arm 78 on the micrometer barrel 56. The microscope has a horizontal section 69 bearing the object lens and an oblique section 70 carrying the eyepiece, an elbow casing 71 joining the sections and containing reflecting prisms. In the section 70 are two glass discs 87, 88 placed face to face, the disc 88 being fixed and the disc 87 rotatable by means of a screw 96 acting on a frame holding the disc, and on the disc 87 is a line 90, and on the disc 88 an inclined line 91 and a scale 92. By means of the adjustments provided, the magnified image of the work may be brought into a position to compare with the lines 90, 91 which indicate the shape and diameter of the work, the microscope being set by the distance of the axis of the part 69 from the axis of the work, as set by the micrometer. A scale 102 on a collar 100 on the chuck, and lines 104, 105 on the chuck are used for setting the tap in correct position in the machine for observation by miscroscope.