Patent GB-541158-A (GB)
Title: Improvements in or relating to broaching machines
IPC: B23F1/08
Filed: 1940-06-03
Abstract: 541,158. Broaching; gear-cutting. STEVENS, A. H. (American Broach & Machine Co.). June 3, 1940, No. 9725. [Class 83 (iii)] In a broaching machine particularly for gears or splined elements a tool-head carries a number of parallel annularly arranged broaches which have supporting means to allow the broaches to be separated from the pull head while the work is positioned and are afterwards engaged with the pull head and drawn past the work. The frame 20 has parallel ways 22 fitted with gibs, 27 to guide a tool-head 29 which is reciprocated by hydraulic cylinders 33 secured to the work plate 34. The pull-head 40 is secured to an extension 291 and is arranged to grasp the upper ends of broaches 42. A stem 43 has an upper portion secured by a nut 45. The lower end of the stem has a part 46 with radial broach-receiving slots intersected by a recess 48 carrying a split ring 50 which forms an upper tool abutment. A second recess 49 carries segmental arcuate jaws 51 which are movable into and out of clamping relation with the tools by means of a sliding cam ring 59 operated by stop pins 62. When the tool-head 29 is completing a downward stroke, ring 59 engages the stop pins and is moved up to disengage the tools which can then be withdrawn downwards by a lifter 63. After positioning the blank W, Fig. 3, on the arbor 64 the tools are raised to the position shown and the lifter movement continues during the rise of the head 29, the ring being moved down by plungers 65 to clamping position. The lifter is operated by a fluid-pressure cylinder 73 which slides over an anchored piston rod 72. The lower ends of the tools are secured to a bushing 75 by a pair of split-ring clamping- members 76, the member 75 being centred by a conical member 84 of the lifter the correct angular position of the broaches being ascertained by the engagement of bars 82 with a forked part of the block 84. The tool guide and work support comprises a member 90, Fig. 5, with a central arbor support 110 and a part 91 fitting in a bore in the work plate 34. The member 90 has downwardly extending webs 94 to form guide slots for the broaching tools 42 which are backed up by the wall 96 of member 90 and by a lower ring 120 surrounding the webs 94. The work arbor 64 is located in a support 110 having radial webs 118 which engage the wall 96 and have lower portions abutting the webs 94. A coolant supply pipe 130 extends into the bore of hub 111 having radial passages 132 leading into the guide slots for the tools. To remove finished work a pair of pivoted fingers 141 overlie the teeth of the work and are normally held in operation by spring plungers 146. As the broaching-tools approach their upper limit the bars 82 engage rods 147 to operate the fingers and eject the finished blank which drops through the bushing 75 onto a movable deflector which directs it into a shoot. The deflector is automatically moved into operative position as the broaches approach their upper limit. The securing bolts 172 for the heads of the cylinders 33 serve also to secure the cylinder structure to the work plate. To guide the upper ends of the tools a split bushing 185 mounted in a plate 149 secured to the machine frame has radial slots through which the tools can pass freely. In operation a pre-formed blank is placed on the work arbor and the lifter moved up to place the upper ends of the tools within the holder 40. When the head is moved upwards on the broaching stroke the jaws 51 are cammed inwards to grip the tools which then pass through the work. The ejector fingers are then actuated by the bars 82. During the return stroke the tools are moved down till the bushing 75 engages the lifter 63. The tools are disengaged by the pins 62 and continued downward movement of the lifter carries the tools clear of the work arbor so that a fresh blank may be positioned.