Patent GB-596926-A (GB)
Title: Improvements in or relating to tube reducing mills
IPC: B21B21/00
Filed: 1945-06-27
Abstract: 596,926. Rolling tubes ; mandrel carriages. THURSTON, A. P. (Rockrite Processes, Inc.). June 27, 1945, No. 16370. [Class 83 (iv)] A tube reducing mill having a mandrel and a pair of co-operating die-rolls which are actuated to reduce the stock, comprises also means for feeding the stock along the mandrel to the die rolls, including a one-way clutch and a fluid-pressure line having at one end a piston connected to the driving member of the clutch and at the other end a plunger, means to hold the mandrel from longitudinal movement while the stock is being fed, means positively connected to both the mandrel and the stock for turning the mandrel and stock including a second one-way clutch, fluid-pressure - line, piston and plunger and means connected with the actuating mechanism of the die-rolls to actuate both of said plungers in a predetermined time relation to each other and to the actuation of the die-rolls. The two die-rolls 70 are fast on their shafts 71 which are mounted in the carriage 73 and are coupled together by gears 76 at each end are also coupled by gears 77 to racks 78 on the framework 79 of the machine. The carriage is suspended from rollers 83 supported on tracks on the frame, as described in Specification 596,965. Gears 85 secured to the rollers 83 and meshing with racks 86 secured to the frame, prevent slipping. The tubular stock S to be reduced is held at its rear end in a collet attached to a gear 2 journalled in a head SF slidable on rails 3 of the machine. A mandrel M is secured at its rear end in a block 9 which may be moved by a sprocket chain 10 driven by an auxiliary motor 11 from its forward operative position to a rear position to allow a fresh tube S to be loaded into the machine. In the normal operation of the machine, the die roll carriage 73 is reciprocated, the stock S is intermittently fed forward and both the stock and mandrel are intermittently rotated through angles of from sixty degrees to ninety degrees. The sequence of operations is : (1) feed of stock ; (2) working stroke of dies ; (3) turning of stock and mandrel and (4) return stroke of dies. The die-roll carriage is reciprocated from a main driving motor DM through gearing 31, 33 and 34 and a pair of crank arms 35. Motor DM also drives a cam 27 mounted in a casing 36, Fig. 3. This cam reciprocates oppositely disposed plungers 40, 41 operating in cylinders 42, 43 connected respectively by piping 44, 45 to cylinders 17 and 22, Fig. 5, in which operate pistons 16 and 21 coupled to the driving members 12 and 13 of two one-way clutches controlled by brake bands 14 so that during the forward strokes of the pistons rotary motion is imparted to shafts 15 and 23 respectively. The working stroke of the pistons may be varied as by means of manually adjustable plungers 47 in reservoirs 46. Shaft 15 is coupled through gears 18, 19, 20 to a nut rotatably mounted in the frame of the machine and serving to feed the stock by means of a hollow screw-shaft 5 extending rearwardly from the head SF. Shaft 23 carries gears 24, 25 which mesh respectively with a gear 26 on the mandrel (when the latter is in its forward operative position) and with the gear 2 secured to the stock-holding collet and so imparts intermittent rotary movement to both stock and mandrel. The return stroke of the pistons 16, 21 may be ensured by a supply of pressure fluid above the pistons at a lower pressure. This fluid supply may also operate locking means 56 for the mandrel block 9 and a sliding cam 59 which, through a follower roll 60 rocks a lever 61 carrying the gear 19 so that the gear moves out of mesh with the feed gear 18 and into mesh with a reversing gear 63 driven by an auxiliary motor 66. This movement of the lever 61 occurs when the stock-carrying head reaches its extreme forward position and operates a four-way valve 57 in the supply lines of the low-pressure fluid supply and effects a rapid return of the carriage until the head trips a switch 67 to stop the motor 66. Relief valves 53 are included in the fluid system operating the pistons 16 and 21 to prevent breakage of a part of the machine in the event of too great a load.