Friction welding

Claim 2

A friction welding machine for performing a friction welding operation including a heating phase and a forging phase, said machine comprising a first workholding device, a second workholding device, means for advancing one of said workholding devices towards the other during the heating phase of a welding operation to bring workpieces held in said workholding devices into contact one with the other, means for rotating one of said workholding devices during the heating phase, means, operative during the forging phase, for locking said advancing means, and means, operative during the forging phase of a welding operation, for converting kinetic energy produced by said workholding device which is rotated during the heating phase into axial thrust urging one of said workholding devices towards the other to provide a greater axial force between the workpieces than is provided by the means for advancing said one workholding device during the heating phase.

Claim 3

A friction welding machine according to claim 1, wherein kinetic energy produced by rotation of said one workholding device is stored in means for storing kinetic energy including a rotatable assembly, and the means for converting the stored kinetic energy into axial thrust comprises two interengaged screw-threAded components.

Claim 4

A friction welding machine according to claim 1, wherein kinetic energy produced by rotation of said one workholding device is stored in means for storing kinetic energy including a rotatable assembly, and the means for converting the stored kinetic energy into axial thrust comprises a cam mechanism.

Claim 5

A friction welding machine according to claim 1, wherein the means for advancing one workholding device towards the other during the heating phase comprises a mechanical lever system.

Claim 6

A friction welding machine according to claim 1, wherein the means for advancing one workholding device towards the other during the heating phase comprises at least one liquid pressure ram-and-cylinder device.

Claim 7

A friction welding machine according to claim 1 comprising a frame, a headstock movable rectilinearly in said frame, a tailstock fixedly mounted in said frame, means for applying thrust to said headstock to urge it towards said tailstock, a rotatable shaft mounted in said headstock, means for driving said rotatable shaft, means for releasing said rotatable shaft for free rotation by stored kinetic energy, a first workholding device carried by said rotatable shaft, a second shaft mounted in said tailstock co-axial with said headstock shaft, a second workholding device mounted on said second shaft, interengaging screw threads on said second shaft and said tailstock, brake means operative for holding said tailstock against rotation, means for locking said headstock against rectilinear movement away from said tailstock, and control means operative for effecting sequentially during a welding operation, advance of said headstock towards said tailstock with said rotatable shaft rotating and said second shaft held against rotation, and release of said rotatable shaft and of said brake means with locking of said headstock against retracting movement, so that said second workholding device is urged axially towards said first workholding device by the action of the screw threads while said shafts are rotated by kinetic energy stored therein.

Claim 8

A friction welding machine according to claim 6, wherein the brake means comprises a disc brake.

Claim 9

A friction welding machine according to claim 6, wherein the brake means comprises a band brake.

Claim 10

A friction welding machine according to claim 1, comprising a frame, a headstock fixedly mounted in said frame, a shaft rotatably mounted in said headstock, means for driving said rotatable shaft, a first workholding device mounted on said rotatable shaft, means for transmitting rotation of said shaft positively to said workholding device in one direction, cam means acting between said shaft and said workholding device whereby rotation of said workholding device in advance of said shaft in said direction of rotation imparts axial movement to said workholding device, a brake operative to hold said shaft against rotation, a tailstock, means mounting said tailstock for rectilinear movement towards and away from said headstock, a second workholding device fixedly mounted on said tailstock, means for moving said tailstock towards said headstock and exerting axial thrust between workpieces mounted in said workholding devices, means for locking said tailstock against backward movement at the end of an approach movement thereof towards the headstock and means for disconnecting the drive to said rotatable shaft and applying the brake thereto at the end of said approach movement, so that continued rotation of said first workholding device by kinetic energy stored therein causes said first workholding device to be urged towards said second workholding device due to the action of said cam means.

Claim 11

A friction welding machine according to claim 9, wherein the means for moving the tailstock towards the headstock comprises a crank lever, a connecting rod connecting said crank lever to said tailstock, and means for rotating a shaft carrying said crank lever, and stop means for engagement by said crank lever in an over-dead-centeR position when the tailstock is fully advanced towards the headstock.

Claim 12

A friction welding machine according to claim 1, comprising a frame, a headstock fixed against axial movement in said frame, a shaft rotatably mounted in said headstock, drive means for imparting rotation to said shaft, a tailstock movable towards and away from said headstock, a first workholding device carried by said shaft, a second workholding device carried by said tailstock and having screw-threaded engagement therewith, a brake which holds said second workholding device against rotation, manually operable lever means for urging said tailstock towards said headstock, means for locking said tailstock against retractive movement at the end of an advance movement towards said headstock and means, operative at the end of said advance movement, for discontinuing the drive to the first workholding device and releasing the brake on the second workholding device, thereby enabling rotation of the workholding devices to be continued by stored kinetic energy, the rotation of the second workholding device, due to its screw-threaded engagement with the tailstock, imparting axial thrust thereto urging it towards the first workholding device.

Claim 13

A friction welding machine according to claim 11, wherein the manually operable lever means comprises a crank lever fixed to a shaft mounted in fixed bearings, a connecting rod connecting said crank lever to said tailstock, and a manual lever fixed to said shaft.

Claim 14

A friction welding machine according to claim 12, wherein the crank lever and connecting rod are arranged to pass through a dead-center position at the end of the approach movement of the tailstock towards the headstock and to engage a fixed abutment to lock the tailstock against retractive movement.

Claim 15

A friction welding machine according to claim 13, wherein the drive means is an electric motor, the brake is an electromagnetic brake, and comprising switch means, operated by the crank lever, for operating an electric circuit to cut off the electric current supply to the said motor, and to release the electromagnetic brake, when the crank lever approaches the fixed abutment.