GB710517A - Improvements in or relating to broaching machines - Google Patents

Abstract

710,517. Broaching. GARRETT ENGINEERING WORKS, Ltd., R. Oct. 22, 1952 [Oct. 22, 1951], No. 24655/51. Class 83 (3) A broaching machine, particularly for torming the arms of T-slots, comprising a number of cutters 4 of progressively increasing size mounted on the links 7 of an endless chain. Two or more chains may cut slots of different sizes, each being driven by a separate motor 15 through reduction gearing and the chains may be horizontal, vertical or inclined. Five cutters 4 are secured in each cutting link 7 by wedges 14 held down by screws and the pivot pins 8 have rollers 9 which engage in notches in the sprockets 5, 6 and also between a pair of guide plates 10, 11 adjacent the work table 3. A vertical gap in both plates 10, 11 provides sideways guidance for the links. The work 1, which already has a straight-sided slot 2, is located on the work table with the sides of the slots engaging closely with the protruding part 7a of two links which are not fitted with cutters and the chain is then set in motion so that successive cutters gradually form the undercut portion of the slot. The first two links may, as shown in Fig. 2, have no protruding portion and be followed by a locating link having a protruding portion 7b. The protruding parts 7a of the cutter links engage the sides of the slots closely so that they also constitute locating links but they may alternatively be narrower than the slot, in which case the cutters keep the work correctly positioned. Where a link acts as a locating link, its leading sides are tapered so that it will enter the slot easily and the front side is bevelled so that, if it cannot enter the slot, it will push the work away. If all the links are formed as cutter links, the size of slot cut can be maintained as the cutters wear by removing the first cutter of the series and placing a cutter of maximum size in a vacant space at the end of the series. Automatic means, such as an air blast, may be provided for removing swarf. The Provisional Specification describes also a common drive for the chains.