Patent GB-302017-A (GB)
Title: Improvements in or relating to metal milling and like machines
IPC: B23C1/00
Filed: 1927-10-29
Abstract: 302,017. London Electric Railway Co., and Chipperfield, W. Oct. 29, 1927. Milling-machines; bar feeds.-In a machine for operating on long work-pieces such as railway rails the work is fed continuously to stationary milling-cutters by means of two tables which carry vices for gripping the work alternately, the tables being reciprocated in the same line but slightly out of phase so that one table may engage the work and commence its feeding; action before the other commences its return stroke. The reversal of one table is controlled by the motion of the other table and the return stroke is made more rapidly than the feeding stroke. Guides are provided near the cutters for supporting the work during cutting. The machine comprises two separate beds 21, 22 Fig. 2 the farmer carrying two sets of cutters 29, 30 and the driving gear therefor driven by an electric motor 23 whilst the latter is provided with guides 32 for the work-feeding tables 35. The machine may operate on any number of rails simultaneously, that shown having four cutters in each set for milling four rails, the cutters 29 acting on the top of the rails and the cutters 30 on the inner vertical edges. A countershaft 25 is driven from the main shaft 24 through a belt drive 28, whereof the pulleys are interchangeable for speed variation. The tables 35 are reciprocated from the shaft 25 by means of bevel pinions 40, 41 rotatable on the shaft, sliding clutches 42 keyed to the shaft, and bevel gears 43, 44 secured to transverse shafts 45, Fig. 1, which carry worms driving, through reduction gearing, worms 51 engaging racks on the under sides of the tables. The bevel pinions and gears are in pairs of different size so that the return stroke will be more rapid than the feeding stroke. Each table carries two pivoted dogs 60b, 61b, Fig. 2, adapted to co-operate with a pair of three-armed levers 56<a>, 56b, pivoted to the bed 22 and provided with rollers 58a, 59<a> &c., lying in the paths of the dogs. Links 55<a>, 55<b> connect the levers with the clutch-operating yokes 53a, 53b. Each link is in two parts connected by a yielding coupling 63 consisting of a piston impinging on each side against a thick rubber washer to allow the clutches to slip into gear easily. The rails are gripped during feeding by vices comprising flanges 70, Fig. 11, for bolting on the tables and side webs 71 tied together by bridges 72, 73. Two removable fixed jaws 74 are attached to the side webs and between these are movable jaws 80 pivoted at 81 and carrying grooved rollers which support and are acted upon by a wedge attached to the piston rod 79 of a pneumatic cylinder 75. The cylinder 75 is pivoted on vertical trunnions 76 to equalize the pressure between the two sets of jaws. The jaws 80 are formed of two plates spaced apart by distances pieces and have face-plates 87 pivoted thereto at 89. The rails are supported on rollers 90 journaled on the vice bases. The work guides on the cutter head comprise bases 120, Fig. 18, shaped at 123 to support the rails 20 and carrying fixed jaws 122 engaging the web on one side. Further jaws 124 engage the other side of the web and the top of the lower flange at 126 and are pivoted at 128 to a plate 130 secured to the base by bolts 131 with the interposition of a hard rubber packing 132 to allow the jaws to accommodate themselves to slight inequalities in the rails. The supply of air to the pneumatic cylinders 75 is controlled by valves 93, Fig. 1, carried by the tables 35 and actuated by stops on stationary pillars 106, 108. In operation, the first table 34a moves forward to feed the work 20 and a lever 104 on the valve 93 engages a pawl 107 thereby rooking the valve to admit air to the cylinders 75 and close the vices during the first three inches of movement. The table 34b is also moving forwards and is within six inches of its forward position when the table 34a reverses. When within four inches of its forward position the lever 103 engages a fixed stop 105 and releases the rear vices during the next three inches of movement, and when the table 34a has moved forward six inches, its dog 60b, Fig. 2, engages the roller 59b and reverses the clutch for the table 34b. When the table 34a is within six inches of its forward position the dog 61b engages the roller 58b and again reverses the rear clutch, thereby starting the table 34b on its slow forward stroke. The vices on the table 34b are closed and those on the table 34a opened as described above, the movement again being allowed to overlap so as to ensure a continuous feed of the work. The vices may be operated otherwise than by pneumatic cylinders, and the machine may be used for operating on wooden and like articles which are of a lengthy nature like rails.