GB509994A - - Google Patents

Abstract

509,994. Testing pitch of helical grooves. MASCHINENFABRIK AUGSBURG - NURNBERG AKT.-GES. Jan. 9, 1939, No. 710. Convention date, Jan. 19, 1938. [Class 106 (ii)] Comprises a method of testing the pitch of helically extending grooves in bores in which the angular displacement of two points at a predetermined distance apart axially in the same groove is'continuously measured and recorded over the entire length of the bore, a curve being obtained which is compared with the ideal curve prepared from the prescribed pitch. A sleeve 1 is closed at the ends by plates 2, 3 to form a drum. The sleeve is surrounded at the ends by rings 4, 5 attached to it and further by axially slidable bushes 6, 7, the bevelled flanges 8, 9 on which enter into recesses in the rings and are pressed apart by a spring 12. The rings have bores arranged in pairs opposite each other in which brackets 19 slide having bevelled faces engaging the flanges, 8, 9 and carry rails 11 which are pressed against the bore by the spring 12. A sheet metal cylinder 13 covers the space between the rings. A partition wall 14 in the sleeve 1 affords a bearing for one end of a shaft 16, the other end of which is mounted in the plate 2. A lever 17 fixed to the shaft 16 passes through a slot in the ring 5 and carries a spring feeler pin 19. In the axial plane passing through the slot there is provided in the ring 4 a bore 21 in which a spring guide bolt 23 works with radial movement. On the shaft 16 is fixed an arm 24. A second arm 26 is arranged between two fixed semicircular plates 27, 28 with its inner end slotted to engage the squared end of a shaft 42. A pin 37 attached to the arm 26 is connected on the one hand by a spring 25 with arm 24 and on the other hand by a much stronger spring 33 to one arm 32 of a two-armed lever 31 the arm 34 of which passes with slight play through a bore in the ring 4 and carries a spring feeler 35. The shaft 42 may be turned from outside by the key 43 so that the pin 37 engages any of three notches each 90 degrees apart on the plates 27, 28. The shaft 16 is geared by toothed wheels 44, 45, 46, 47 to the pick-up 49 working over the resistance drum 50 of a telewriter. In use,. the pin 37 is placed in the central notch and the device inserted in the bore with feelers 19, 23 in the same groove and feeler 35 in a diametrically opposite groove. The key 43 is now manipulated to place the pin 37 in one of the other slots depending on which way the device is to be pulled through the bore. The spring 25 will turn the arm 17 so that it engages a flank. The drum 50 is adjusted by button 54 to turn the whole drum so that feeler 23 also engages the same flank. By moving the pin through 180 degrees the feelers impinge on the opposite flank. The drum 50 is adjusted by button 54 to the initial point of the chart and the device when pulled draws a curve from which comparisons with the ideal curve are made.