Fast response weld head
First Claim
1. A method of rapid precision welding of an object comprising the steps of:
- (a) providing a movable electrode;
(b) moving the electrode into contact with the object using a fast response weld head on which the electrode is mounted;
(c) increasing the force exerted by the electrode to a first predetermined level;
(d) applying electrical welding energy through the electrode to the object for a predetermined duration of time;
(e) holding the force exerted at said first level for a first length of time as the object softens;
(f) increasing the force exerted to a second predetermined level for a second shorter length of time; and
(g) returning the electrode force to said first predetermined level during the remaining portion of the interval of application of weld energy wherein the electrode maintains contact with the object at all times during welding eliminating expulsion of material.
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Accused Products
Abstract
A fast response weld head which employs a control system to allow user control of critical welding parameters such as speed, force, position, and duration. In one embodiment, the control system includes a position servo loop attached to a motor driven output shaft on which a welding electrode is mounted utilizing a follow-up spring assembly. During a weld cycle, the control system moves the welding electrode toward a workpiece at a rapid user-defined rate. Just prior to when the electrode is reduced to prevent damage to the parts. When contact is made, the force exerted by the electrode on the workpiece is measured until the measured force equals a user-defined optimum welding force. A user-defined weld current is enabled to the electrode. When the weld is complete, the welding electrode is automatically raised by the control system, releasing all pressure on the workpiece. In a second and presently preferred embodiment, a linear magnetic actuator is utilized in lieu of a motor to drive the output shaft. The follow-up spring assembly is eliminated. The force required to keep constant pressure on the weld is now provided by programming the linear actuator to exert a very short pulse of force to maintain constant pressure on the weld as the weld softens at the onset of applications of weld current. Force is then returned to normal force until the weld is complete.
44 Citations
23 Claims
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1. A method of rapid precision welding of an object comprising the steps of:
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(a) providing a movable electrode; (b) moving the electrode into contact with the object using a fast response weld head on which the electrode is mounted; (c) increasing the force exerted by the electrode to a first predetermined level; (d) applying electrical welding energy through the electrode to the object for a predetermined duration of time; (e) holding the force exerted at said first level for a first length of time as the object softens; (f) increasing the force exerted to a second predetermined level for a second shorter length of time; and (g) returning the electrode force to said first predetermined level during the remaining portion of the interval of application of weld energy wherein the electrode maintains contact with the object at all times during welding eliminating expulsion of material. - View Dependent Claims (2, 3, 4, 5)
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6. In a fast response weld head, control means comprising:
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means for selecting a force to be applied by an electrode on an object to enable low impact contact; means for varying the speed of movement of the electrode relative to the object; means, comprising a linear magnetic actuator, for varying the level of force exerted by the electrode on the object; and means for increasing the force exerted by the electrode on the object at a predetermined rate prior to the start of weld energy wherein control of the speed of the electrode enables low impact contact with the object minimizing movement of and damage to the object. - View Dependent Claims (7, 8, 9, 10, 11)
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12. A method of rapid precision welding of an object by an electrode with user-controlled parameters comprising:
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(a) providing a movable electrode; (b) generating a speed control signal defining a rate of motion of the electrode; (c) generating a predetermined force control signal defining a first force to be applied to the object by the electrode; (d) generating a position control signal defining a displacement of the electrode relative to the object; (e) generating a duration control signal defining a length of time the electrode contacts the object; (f) driving the electrode toward and into contact with the object; (g) rapidly increasing the force applied by the electrode after contact; (h) applying welding energy to the object through the electrode for a predetermined interval; (i) generating a transient force greater than said first force for a brief interval during the weld energy interval and prior to the end of the time interval when the electrode contacts the object; and (j) rapidly decreasing the force applied by the electrode after the weld energy interval to minimize the overall time interval of each welding operation.
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13. In a fast response weld head, force controlling means comprising:
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means for programming a prescribed force control signal representative of a force to be applied by an electrode on an object; and means, comprising an open loop control circuit, for programming a transient force applied by the electrode to the object; and means for maintaining the prescribed force and transient force exerted by the electrode on the object for predetermined intervals. - View Dependent Claims (14, 15)
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16. A fast response weld head comprising:
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a support means; means for mounting a movable shaft on the support means permitting motion of the shaft relative to the support means; driving means, comprising a liner magnetic actuator, for moving the shaft linearly with respect to the support means; operator controlled means for controlling a force to be exerted by the weld head; means for maintaining the operator controlled force between the electrode and the workpiece for a predetermined duration; and means for applying a transient amount of force during the force maintaining interval. - View Dependent Claims (17, 18, 19)
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- 20. A fast response weld head comprising the combination of a control system attached to magnetic linear actuator means, driving means attached to the actuator means, and welding means attached to the driving means.
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23. A fast response weld head comprising:
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a servo control means for controlling position of an electrode relative to an object; detecting means coupled to the servo control means for detecting electrode contact with the object; open loop control means for controlling the force exerted by the electrode in response to a current; and control switching means coupled to the detecting means for changing control of the electrode from the servo control means to the open loop control means upon detection of electrode contact with the object.
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Specification