Patent GB-253797-A (GB)
Title: Improvements in machines for facet filing of saw teeth
IPC: B23D63/10
Filed: 1925-11-20
Abstract: 253,797. Janson, C. A. Nov. 20, 1925. Filing machines and apparatus, reciprocating.- A machine having a reciprocating file is used for operating on saw-teeth so as to bevel both edges of each tooth on opposite sides alternately as shown in Fig. 5. The file acts on one edge at a time without touching any others and acts on the two edges of a tooth successively without the saw being fed. The machine is set in operation by introducing a saw between the holding jaws and depressing a pedal, the operation continuing automatically until all the teeth have been filed when the machine is stopped automatically and the jaws are opened for the replacement of the saw. A three-cornered file 11 is mounted in a holder 1 rotatable about vertical pivots 12 and carried by a slide 2 which is reciprocated in vertical guides 3 by a lever 5 pivoted at 6 and oscillated by a cam 8. The projection of the file beyond the holder is adjusted bv screws 10. and the holder is oscillated about the pivots 12 by a rod 13 connected by springs 13<a> to a bell-crank lever 15 actuated by a cam 17. The inclination of the file is controlled by two guide surfaces 21 which are adjustable by screws 22, Fig. 3, and act upon a roller 19 carried by an arm 18 on the file-holder. The saw 62 is gripped between jaws 25, 27, the former being carried by arms 26 rigidly secured to a shaft 24 and the latter by arms 28 loose on the shaft. The jaws are normally closed by springs 29, Fig. 4, and the shaft is oscillated by a lever 31 and a cam 30, 30<1>. The back of the saw engages a roller 60, Fig. 3, mounted on a spring- pressed lever 61. In operation, a saw is inserted between the open jaws until the end of it engages a bevelled surface on a finger 36 which is then oscillated about the shaft 24 and by means of a lever 37 and link 38 lifts a hook 39 out of the path of the stop 40 on the lever 31. The treadle 48 is then depressed and engages a friction or toothed clutch (not shown) to rotate the shaft 9 and simultaneously releases a band-brake 54 on the latter shaft. A stop 42 is rotated by a spring (not shown) about the shaft 43 against a stop 44 and locks the treadle in the lower position. The lever 31 then moves down and causes the jaws to grip the saw and oscillate about the shaft 24 to position it with regard to the file. After the file has made one or more upward working strokes the cam 30<1> raises the saw just clear of the file and the latter is then oscillated about the pivots 12 to position it for filing the other edge of the same tooth. The saw is again lowered and after one or more further strokes of the file the cam 30 lifts the saw well clear of the file for indexing. This is effected by a finger 57 which engages the saw teeth when the latter is raised and is moved axially along the shaft 43 by a cam 58 and mechanism (not shown). The saw is released from the jaws when these are lifted by the cam 30 owing to screws 35 on the lower jaw-levers 28 engaging the shaft 34. Simultaneously with the movement of the saw the file is oscillated to operate on the adjacent edge of the next tooth. When all the teeth have been filed the finger 36 rides over the end of the saw and oscillates about the shaft 24 to lower the hook 39 into the path of the stop 40. The latter withdraws the stop 42 from the treadle mechanism and allows the treadle to be raised by a spring (not shown), thus disengaging the driving clutch and applying the brake 54.