Upsetter Forging Machine

Overview

An upsetter forging machine, also called a horizontal forging machine or header, forms the end of a hot bar by gathering and compressing metal against a clamped length of stock. Unlike a vertical press, the upsetter works on a horizontal axis: a gripper holds the bar across its diameter while a horizontal ram drives a punch into the projecting heated end and upsets it. The machine makes bolt heads, flange ends, valve blanks, axle shafts, and similar parts where one end of a bar must carry much more metal than the shank. Because the gripper holds long stock that passes right through the dies, an upsetter can work on bar that is far longer than the machine, which a closed press cannot do. Header force ranges from about 100 t on small machines to 1600 t on the largest, at 30 to 90 strokes per minute.

How upsetting works

The heated bar end is pushed past the open gripper dies until it meets the Stock Stop, which sets how far the end projects and so fixes the volume of metal that will be gathered into the head. The Gripper Die Mechanism then clamps the bar: the Stationary Gripper Die holds the datum side and the Moving Gripper Die, carried on the Gripper Slide, closes from the other side. With the bar held, the Heading Slide drives a Heading Punch axially into the projecting end and upsets it. A long projection cannot be headed in one blow because the unsupported metal would buckle, so the work runs across two to four passes. The Coning Tool gathers and cones the end first, later punches build the bulk, and the final punch forms the head profile. Between passes the Tool Index Slide indexes the punch block so the bar meets each tool in turn, and after the last pass the Kick-Out Pin ejects the finished part.

Heading slide and drive

The Heading Slide is driven by the Crankshaft through an Eccentric and a Connecting Rod joined to the Header Ram by a hardened Wrist Pin. The eccentric throw sets the maximum stroke, and the Stroke Adjuster sets the shut height so the punch reaches the bar at the right point of travel. The ram slides on Ram Gib strips that keep the punch centred on the gripped bar. Energy comes from the Main Drive, where a Main Drive Motor of 30 to 250 kW keeps a heavy Flywheel spinning between strokes. The Clutch-Brake Unit couples the flywheel to the crankshaft for a single stroke on demand and stops the crank at top of stroke. The motor only restores the speed the flywheel loses, so it can be far smaller than the peak heading power. Drive runs through a Drive Belt set, a Drive Pinion, and a Helical Gear Pair in a Gearbox Housing, with an Encoder reporting crank angle.

Gripper timing

Clamping must lead the heading stroke, because the dies have to hold the bar before the punch arrives and must not release until the upset is finished. The Gripper Cam Linkage sets this timing. A Gripper Cam on the crankshaft drives a Cam Follower and a Rocker Lever that pushes the gripper slide, and a Toggle Link goes near dead centre as the dies close so a modest cam force produces the high clamp load that resists the upset force. A Lock Wedge takes up slide clearance so the dies do not back off under load, and Coil Spring elements return the follower onto the cam. The dies sit in a Die Holder that can be changed for a different bar diameter.

Tooling, hydraulics, and cooling

The Heading Tooling block carries the punches in a Punch Holder and reacts the axial load through a Backstop Block. Hot upsetting is hard on tools, so the Lubrication and Die Cooling system sprays graphite release agent from a Spray Header onto the dies and punches between strokes, metered by a Lubricant Pump from an agitated Lubricant Mix Tank. The Oil Circuit feeds the crankshaft bearings, ram gibs, and gripper slide, and the Scale Blow-Off clears furnace scale off the bar before heading. The Hydraulic Power Unit supplies the gripper boost and kick-out cylinders: a Hydraulic Pump gives 160 to 250 bar, a Valve Manifold sequences the motions, an Accumulator steadies clamp pressure, and a Oil Cooler holds oil temperature down near the hot dies. A Pressure Sensor confirms grip pressure each stroke.

Control, frame, and materials

The Control Cabinet cabinet houses a PLC Control that ties clutch engagement, gripper close, spray, and kick-out to crank angle, with a Operator HMI holding stroke rate, pass settings, and counts per part number. A Drive Module feeds the motor through an IGBT Power Module stage and a Power Supply, wired by a Wire Bundle to a Connector panel and switched by a Relay bank. The whole machine sits on the Machine Frame, a heavy Main Frame casting pulled together by a Tie Rod set so the heading force is carried in tension. Gripper dies and punches are H13 or 5CrNiMo hot-work tool steel hardened to resist heat and abrasion, the crankshaft and connecting rod are forged 42CrMo4, and bars enter at 1050 to 1250 deg C for carbon and alloy steels. An upsetter is often the head-forming station on a line that feeds bolt, axle, and valve production where one end of a long bar must gather far more metal than the shank.