Metal fusion bonding – Including means to provide heat by friction between...
Patent
1986-12-30
1987-10-27
Godici, Nicholas P.
Metal fusion bonding
Including means to provide heat by friction between...
228 443, 228113, B23K 2012, B23K 2700
Patent
active
047024054
DESCRIPTION:
BRIEF SUMMARY
The invention relates to friction welding apparatus.
In conventional friction welding, relative rotation between a pair of workpieces is caused while the work pieces are urged together. Typically thereafter once sufficient heat is built up at the interface between the workpieces, relative rotation is stopped and the workpieces are urged together under forging force which may be the same as or greater than the original urging force.
Conventional friction welding apparatus typically includes complex electronic controls for controlling the different forces which must be applied and for controlling drive means in a selective manner to control relative rotation of the workpieces.
In accordance with the present invention, friction welding apparatus comprises a housing; a workpiece support rotatably and axially movably mounted in the housing; a fluid pressure operated drive coupled to the workpiece support for causing the workpiece support to rotate relatively to the housing; resilient means for urging the workpiece support in a first axial direction relatively to the housing; pressure means responsive to fluid pressure to move the a workpiece support relative to the housing in a second axial direction opposite to the first direction; a fluid inlet in the housing; fluid conveying means for communicating fluid under pressure from the inlet along a first path to the drive and along a second path to the pressure means; and control means responsive to axial movement of the workpiece support in the housing for controlling the fluid pressure communicated along the first path whereby as the workpiece support moves in the housing under the influence of the pressure means, the first path is gradually closed while the second path remains open.
The invention simplifies the known friction welding apparatus by providing a common inlet for fluid under pressure which is then used initially to operate a drive and to urge the workpiece support in the second direction. Subsequently, the first path will be closed so that the drive will cease to operate and the fluid pressure will be fully applied through the second path to the pressure means. Thus, the friction welding apparatus automatically changes from a first condition in which the drive rotates the workpiece support and the support is urged in the second direction (usually under a comparatively light force) to a second condition in which rotation has stopped and the workpiece support is urged in the second direction under forging force. No operator intervention during the weld cycle is required.
The invention enables portable friction welding apparatus to be developed which is simple to operate in a construction site environment without electric or electronic controls.
The control means could include one or more electronic transducers for axial monitoring movement of the workpiece support and for generating suitable control signals to control the motor and fluid supply.
Preferably, the control means comprises a valve body with an input port communicating with the fluid inlet, output ports communicating with the first and second fluid paths respectively, and a valve member movable in the valve body in response to relative axial movement between the workpiece support and the housing to control fluid communication between the input port and the output port connected to the first path while maintaining the connection between the input port and the other output port. With this arrangement, no electronic controls are required and the apparatus operates simply under the influence of the fluid pressure.
For example, the valve body may comprise a valve seat cooperating with the valve member, one of the valve member and valve seat being connected to the housing and the other being connected to the workpiece support.
It is convenient for the drive to be axially fixed relatively to the workpiece support. In this case, axial movement of the worpiece support relative to the housing will be accompanied by axial movement of the drive.
In some examples, however, the workpiece support could be
REFERENCES:
patent: 3616980 (1971-11-01), Padilla
patent: 3704821 (1972-12-01), Loyd et al.
patent: 3882593 (1975-05-01), Lucas
patent: 4213554 (1980-07-01), Sciaky
patent: 4593848 (1986-06-01), Hochbein
Heath Thomas V.
Thomson Allan R.
Godici Nicholas P.
Heinrich Samuel M.
Thomson Welding & Inspection Ltd.
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