GB1562782A - Pressbrake machines for bending meta sheets - Google Patents

Description

(54) IMPROVEMENTS IN PRESSBRAKE MACHINES FOR BENDING METAL SHEETS (71) We, A. KINGHORN & COM PANY LIMITED of Stackhills Road, Tod- morden, County of Lancaster; a British Company do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to improvements in pressbrake machines for bending metal sheets.

Pressbrake machines are formed with a stationary lower die and an upper vertically reciprocating beam operated by a motor driving a clutch and a flywheel or other Kinetic Energy store to provide a pressure build up.

In pressbrake machines the machine must be capable of stopping within 200 milliseconds (H.AtFJ. stipulation) and difficulty has been experienced in such machines in obtaining a satisfactory stopping time therefor as such machines use means for storing Kinetic Energy such as flywheels which makes the machine top heavy.

The object of the present invention is to simplify the drive and render the machine more efficient According to the invention a pressbrake machine for bending metal sheets comprises a stationary lower die and an upper reciprocating beam operated by an eccentric or crank driven by an electric motor unit having a tapered or conical rotor which on starting up operates the beam by drawing in the rotor against spring pressure and when stopping the machine the rotor is moved away from the stator by the spring.

The invention will be described with reference to the accompanying drawings: Fig. 1 is a side elevation of the machine; Fig. 2 is a view on line 2-2 Fig. 1 show ing the driving motors with the press in long and short dot dashes.

A pressbrake machine is formed with a stationary lower die 1 and an upper vertically reciprocating beam 2. The main drive is sup- plied by a one piece power unit comprising two motors A, B, a main reduction gear box C and an epicyclic gear box D and incorporating a conical or tapering rotor or armature which is movable longitudinally relatively to the stator, all of known construction.

In starting up the machine the rotor is drawn into the stator against spring pressure releasing a conical brake lined with friction material. To stop the machine current is cut off and the rotor moves back with the spring pressure applying the brake.

The upper or top beam 2 is driven by the motor unit giving the beam a vertically reciprocating motion through an eccentric 3 or a crank. The drive from the motor unit is through a spur wheel 4 driving a second spur wheel 5 rotating a crank shaft 6 carrying the eccentric 3.

Depth adjustment may be provided through a worm and worm wheel on each connecting rod and a dog clutch may be provided so that the tools may be positioned parallel to each other.

Clamping rails 7 are provided to attach tools to the top beam. The bottom die 1 is formed with a table with lateral tee slots to affix tools and tapped holes in the table sides for affixing clamping plates and gauges.

The main drive is supplied as above described by the unit comprising the two motors, the epicyclic gear box and the main reduction gear box with a fail to safety braking system.

The unit may thus be readily removed from the machine frame for reconditioning.

The stroke of the beam is a powered rapid approach-slow bend-rapid return for most bending work but fully fast (for punching work) or fully slow (for bending to lines etc.) can be set by a control switch. The drive may be stopped and reversed away from the work piece for repositioning if necessary.

The output power from the unit may be preset to bend 4 ft. by 1/4 inch mild steel sheet over a 1 inch vee or as a tonnage of 30 tons and if this figure is exceeded the unit is overloaded and cuts out. A warning light indicates any overload. Higher tonnage machines are being developed up to 90 tons capacity.

The initial presetting of the unit output provides a safe working factor while bendin but allows full power of the unit to be used in reverse to withdraw the tools from any overload.

The output figures from the unit vary with the speed selection but the maximum available may be: Fast 1600 productive strokes per hour Vari-speed 800 ,, ,, ,, Slow 300 The electrical control circuit controls not only the power unit but provides interlocks and overloads to ensure safe operation of the pressbrake. Warning lights indicate the various functions both for operating facility and malfunction conditions.

The beam may be backed off the workpiece without passing through a full stroke.

The machine has the following advantages over existing pressbrakes: 1. The self contained power unit eliminates the normal fly wheel clutch and brake unit and air control equipment. No fly wheel eliminates stored Kinetic Energy which is a source of danger.

2. The vari-speed gives two speeds from the unit, one fast and one slow, having the following combination: fully fast, fully slow and fast approach, slow bend and fast return.

3. Instant beam reversal since there is no fly wheel to stop.

4. Full overioad protection as the moors are stopped and started on evcry stroke and the amperage taken by the motors is monitored and trips fitted to operate over the safe load.

WHAT WE CLAIM IS: 1. A pressbrake machine for bending metal sheets comprising a stationary lower die and an upper reciprocating beam operated by an eccentric or crank driven by an electric motor unit having a tapered or conical rotor which on starting up operates the beam by drawing in the rotor against spring pressure and when stopping the machine the rotor is moved away from the stator by the spring.

2. A pressbrake machine as in claim 1 in which the drive from the motor unit is through a pair of spur wheels driving a crank shaft carrying the eccentrics.

3. A press brake machine for bending metal sheets substantially as described with reference to the accompanying drawings.

Dated this 28th day of February, 1978.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (3)

**WARNING** start of CLMS field may overlap end of DESC **. in reverse to withdraw the tools from any overload. The output figures from the unit vary with the speed selection but the maximum available may be: Fast 1600 productive strokes per hour Vari-speed 800 ,, ,, ,, Slow 300 The electrical control circuit controls not only the power unit but provides interlocks and overloads to ensure safe operation of the pressbrake. Warning lights indicate the various functions both for operating facility and malfunction conditions. The beam may be backed off the workpiece without passing through a full stroke. The machine has the following advantages over existing pressbrakes:

1. The self contained power unit eliminates the normal fly wheel clutch and brake unit and air control equipment. No fly wheel eliminates stored Kinetic Energy which is a source of danger.

2. The vari-speed gives two speeds from the unit, one fast and one slow, having the following combination: fully fast, fully slow and fast approach, slow bend and fast return.

3. A press brake machine for bending metal sheets substantially as described with reference to the accompanying drawings.

Dated this 28th day of February, 1978.

3. Instant beam reversal since there is no fly wheel to stop.

4. Full overioad protection as the moors are stopped and started on evcry stroke and the amperage taken by the motors is monitored and trips fitted to operate over the safe load.

WHAT WE CLAIM IS:

1. A pressbrake machine for bending metal sheets comprising a stationary lower die and an upper reciprocating beam operated by an eccentric or crank driven by an electric motor unit having a tapered or conical rotor which on starting up operates the beam by drawing in the rotor against spring pressure and when stopping the machine the rotor is moved away from the stator by the spring.

2. A pressbrake machine as in claim 1 in which the drive from the motor unit is through a pair of spur wheels driving a crank shaft carrying the eccentrics.