GB981775A - Improvements in or relating to punching machines - Google Patents

Abstract

981,775. Punching. HOUDAILLE INDUSTRIES Inc. April 7, 1961 [Nov. 1, 1960], No. 12616/61. Heading B3W. A structure, for accurately positioning a workpiece in relation to a predetermined reference point, comprises a work support table, an elongate rigid member supported on the table and having therein a series of spaced gauging holes and having a gauging surface, a bracket slidable on the rigid member and a direct reading gauge secured to the bracket and having a spindle engageable with the gauging surface of the gauge plug, the bracket having a reference surface perpendicular to the rigid member for engaging an edge of the workpiece. A punching machine including the positioning device comprises a C-shaped frame 31 having upper and lower arms 31a and 31b respectively. The lower arm 31b supports sub-table 50, on which is mounted a work supporting table 33, and also supports a bed 38 on which the lower tool is mounted. A punch and stripper assembly 40 is supported by an upper tool support 41 which is held to the upper arm by clamps 42 and 43. The support 41 comprises arms 41a and 41b and between them is a reciprocating shaft 47 continuously driven by an eccentric 46 and selectively coupled to a ram 44 by an electrically operated clutch of the type described in Specification 890,250. Workpiece supporting table.-The table 33 is adjustable vertically by three screw jacks 58, which are operated simultaneously by a hand wheel 63. Movement of the table in a horizontal plane is prevented by guide pins 64 passing through bushes 67 secured to the subtable 50. Removal of the workpiece can be assisted by lowering the table relative to the die. Lower tool mounting. Fig. 5.-The support for the die 39 is secured to the lower arm 31b and includes a pad 69 to which is screwed a bolster 70 having a recess 72 which receives a cylindrical member 73, also held by screws and locked against rotation by a key 87. An element 75 is a sliding fit in the member 73 and of such a length as to define a recess to receive the die 39. Removal of the die is facilitated by a pin 76 which is moved axially by an eccentric 82 formed on a shaft 77 which has a handle 78. To fix the angular position of the die a key 91 is accommodated in a radial keyway 89 formed in the member 73 and a corresponding keyway 92 in the die. A further keyway may be formed in the die, spaced 90 degrees from the first. Infinitely variable angular positioning of the die is achieved by the provision of a ring 94 which seats in a recess 93 in the member 73, and which is secured to one side of the key 91. When the ring is inverted from the position shown in Fig. 5 the key 91 is still engaged with the keyway 92 but is free of the keyway 89, so that the die and ring are free to rotate to any position, the ring subsequently being locked by a plurality of screws 95. Upper tool mounting, Fig. 6.-The upper tool support 41 is recessed to receive a flanged member 97 which can be locked in any position by screws 98, and which has a keyway 111 which receives one end of a key 113. A punch and stripper assembly 99 is slidable in the annular member and comprises a sleeve 100 within which is a punch driver 101. A punch 109 is retained in the punch driver by a screw 110 and locked against rotation by a key 116. The punch driver has a keyway 112 which receives the other end of the key 113 which passes through and is secured in, the sleeve 100. A stripper 118 is attached to the sleeve 100 by a spring clip 119, and a series of stripper springs 105 act between the upper end of the sleeve 100 and a ring 106 which engages, with the punch driver 101, the underside of a driver head 107. A set of lifting springs 117 acts between the flanged member 97 and the assembly 99 to bias the assembly away from the die. Alignment of punch and die, Fig. 7.-When the punch and die are of non-circular crosssection, angular alignment is achieved by removing the die 39 and the assembly 99 and fitting a lower aligning tool 120 and an upper aligning tool 121 which have keyways corresponding to those on the die and the punch assembly, the lower tool having alignment pins 122 which enter recesses 123 in the upper tool 121. Upper tool support clamping mechanism, Figs. 12 and 16.-The arms 41a and 41b of the upper tool support are held against the frame 31a by two similar clamps 42 and 43 so that the upper tool is accurately aligned with the lower tool. Each clamp comprises a pivoted hook 157 which engages a pin 158 in a support arm and draws the arm against a locating face on the frame. The hook is operated by lever 155 having a handle 155a, and having cam disc 159 which enters a recess in the hook. A plunger 168 on the handle operates a normally open micro-switch 171 on the frame when it reaches the closed position. The machine cannot be operated unless both the microswitches are closed. If either clamp is released the upper tool support can be pivoted about the pin 158 engaged by the other clamp to provide access to the lower tool. Gauging mechanism.-The work positioning mechanism comprises a rail 172, 173 at each side of the table 33, and includes a rack-like member 174 which is parallel to the rail 172 and is rotatably supported in end bearings. A block 176 slides on each rail and the blocks are connected by a base member 182 and a back bar 183 which is clamped as at 184. The forward face of the base member 182 forms a work-engaging surface and secured to the base member is a gauge bar 186 which has a series of uniformly spaced gauge holes 187 and a threaded hole 188 between each pair of guage holes. Slidably supported on the back bar 183 are a number of finger stops 189 and a micrometer supporting bracket stop 190, Fig. 17. The stops are positioned by means of a gauge plug assembly comprising a plate 191, a gauge plug 192 which enters one of gauge holes 187 and a locking screw 194 which engages the corresponding threaded hole 188. The bracket stop 190 has mounted thereon a micrometer head 195, the spindle of which engages the gauge plug 192 so that the bracket may be positioned relative to the gauge plug. An abutment member 197 is secured to the bracket 190 and has a reference surface 197a which is engaged by an edge of the workpiece adjacent to that which engages the forward face of the member 182. The member 197 also has a second abutment surface 197b which is spaced from the surface 197a by the thickness of an abutment member 198 forming part of a finger stop 189, so that the micrometer bracket stop can be used to position the finger stops and can also be used as a work-stop. There is a slot 199, Fig. 18, in the bracket stop, so that after the clamping screw 200 has been removed the bracket stop can be moved to a position on the back rail at which there are two flats and then removed. Each finger stop 189 comprises a bifurcated body 203 in which is pivoted an abutment member 198, and a screw-operated clamp 204. Indicating position of gauging stops.-Mounted on the slide block 176 are a pair of blocks 208, 209 which embrace the member 174 and which are controlled by a manually operated screw 212. The block 208 has thread teeth 208a formed therein which engage with a thread formed on the member 174. At one extreme position of the screw 212 both blocks are clear of the member 174 and the block can move freely along the member, at an intermediate position the threads 208a engage the member and the block 176 can be moved by rotating the member 174, and at a second extreme position of the screw, both blocks are clamped to the member 174 and prevent any movement. A primary method of indicating the fore and aft position of the gauging stops comprises a counter 178 which is attached to the block 176 and is driven by gear-wheels 226 and 228 from a gear-wheel 230 which engages the teeth of the member 174. For fine positioning of the gauging stops, the screw 212 is operated until the teeth 208a engage the thread teeth on the member 174 and the member is then rotated to move the slide block. There is a graduated thimble on the end of the member 174 to give an accurate indication of the position. Template follower mechanism.-The back bar 183 also slidably supports a template follower 253 which engages a template 254 which is secured to the right-hand half of the table by a sheet coated on both sides with a pressure sensitive adhesive. Electrical control, Fig. 27.-The machine is controlled by a start switch 266, a stop switch 268 and a selector switch 270 which in one position directs power to a foot switch 271 by which single strokes of the ram are effected and in the second position directs power to a switch 272 which is incorporated in the template follower mechanism and is part of circuit by which continuous reciprocation of the ram is effected. Specifications 981,776, 981,777, 981,778 and 981,779 are referred to.