GB979311A - Improvements in or relating to swaging machines for the internal profiling of tubular workpieces,particularly of barrels for firearms - Google Patents

Abstract

979,311. Swaging machines. GES FUR FERTIGUNGSTECHNIK UND MASCHINENBAU G.m.b.H. Dec.11, 1961 [June 6, 1961], No. 44160/61. Heading B3H. In a swaging machine for internal profiling of tubular workpieces, by hammering on a mandrel whilst the workpiece is gripped between a feeding gripping head and a holderup, a back pressure which is constantly applied to the holder-up is automatically varied, by means of a valve, in accordance with changes in wall thickness and/or the required internal shape. Thus, optimum axial compression to prevent axial metal flow is applied at all times. In operation, the workpiece 21 is gripped in a sleeve 7 of the gripping head 3 and rotated through a worm and worm-wheel drive 8. Feed of the workpiece to and through the hammers 1 is to the left and is effected by hydraulic cylinders 6 mounted on a forging box 1<SP>1</SP> and piston rods 4 attached to the gripping head 3. The holder-up comprises a cylinder 11 and piston 12, whose rod carries a rotatable holderup head 10, and the back pressure is controlled by a pressure setting valve 24, a control valve 27 and associated cam 28 mounted on the gripping head 3 and a follower 29. The cam 29 controls the seating pressure of a valve plunger 30 through a spring 31 which, through a conduit 34, controls the displacement of a spring-loaded piston 32 in the pressure setting valve 27. The piston 32 has an orifice 33 through which a portion of the fluid displaced from cylinder 11 passes to the control valve. The flow rate from and hence the pressure in cylinder 11 is dependent on the position of the face 37 of the piston 32 with regard to the outlet to conduit 25. In an alternative embodiment, the back pressure in the cylinder 11 is controlled by a series of relief valves with different settings which are alternately or successively brought into operation by solenoid operated slide valves in the return conduit which are operated by limit switches in response to movement of the gripping head. The mandrel is carried on a rod 15 which extends through the gripping sleeve 7 to a piston 16 mounted in an hydraulic cylinder 17 which is slidable in a second cylinder 18. The embodiment described is a rifled barrel, and if it is required to form the cartridge chamber, the mandrel must be carried to the left with the workpiece during this swaging stage. Thus the gripping head 7 engages the end face of the mandrel (Fig. 7, not shown) which is moved to the left by the gripping head 7. This is made possible by the provision of a relief valve in the conduit 19, allowing the cylinder 17 to slide in the cylinder 18.