Constant-tension wire conveying device and tension measurement method

Abstract

The invention provides a constant-tension wire conveying device and a tension measurement method. The constant-tension wire conveying device comprises a wire storage cylinder, an electrode wire, an upper wire discharge wheel, a lower wire discharge wheel, a wire tightening mechanism, an upper guide wheel and a lower guide wheel. The constant-tension wire conveying device is characterized by further comprising an upper tension measurement wheel, an upper tension measurement sensor, a lower tension measurement wheel, a lower tension measurement sensor and a tension control circuit; the wire tightening mechanism comprises a connecting plate, a connecting plate driving device, an upper wire tightening wheel, an upper shock absorber, a lower wire tightening wheel and a lower shock absorber; onan electrode wire conveying path, the upper tension measurement wheel is located between the upper wire tightening wheel and the upper guide wheel, and the lower tension measurement wheel is located between the lower wire tightening wheel and the lower guide wheel; in the moving process of the connecting plate, the wrap angle where the electrode wire makes contact with the upper tension measurement wheel and the wrap angle where the electrode wire makes contact with the lower tension measurement wheel remain unchanged. Tension of the electrode wire at the upper end of an electric discharge machining area is transferred to the upper tension measurement sensor through the upper tension measurement wheel; the tension of the electrode wire at the lower end of the electric discharge machining area is transferred to the lower tension measurement sensor through the lower tension measurement wheel. The two parts of tension are added to serve as the basis for conducting constant-tension closed-loop control over the electrode wire.

Description

technical field [0001] The invention relates to a reciprocating wire-feeding type numerical control wire electric discharge cutting machine, in particular to a machine with two characteristics of constant tension control of electrode wire and stable wire feeding composed of three and two types of different functional mechanisms in series. wire device. Background technique [0002] Wire-cut electric discharge machine is a kind of special processing machine tool that uses thin metal wire as electric spark pulse discharge between the wire electrode and the workpiece, and uses the electric erosion effect generated by pulse discharge to carry out cutting processing. Constant wire electrode tension and stable wire feeding are two necessary conditions for this type of machine tool to obtain high processing efficiency and excellent processing quality. Foreign countries only produce unidirectional low-speed wire-feeding WEDM, which uses wire electrodes to move wire in one direction ...

AI Technical Summary

Problems solved by technology

Further analysis found that: during reciprocating bidirectional movement, the dynamic tension of the electrode wire segment in the state of drawing wire is greater than that of the wire electrode segment in the state of unwinding wire. There are two states of wire unwinding, so between the upper first reversing wheel 36 and the lower first reversing wheel 37 installed at both ends of the first reversing arm 41, there is always an electrode that alternately changes direction as the wire feeding direction changes. Wire tension difference, after mechanical analysis, it will be multiplied by 1 / 2 length of the first reversing arm to form a moment; in this structure, the counter torque generated on the upper guide rail 111 and the lower guide rail 112 will automatically balance the torque ; Therefore, the upper and lower two parts of the electrode wire tension are not all applied to the load cell 31, resulting in measurement errors

The tension of the electrode wire measured by the force sensor of this mechanism is actually always close to four times the dynamic tension of the smaller electrode wire in the upper and lower parts of the electrode wire, which is in the state of unwinding, so that the precise control of the electrode wire tension cannot be truly realized.

[0006] 2. There is a technical problem that machine tool resonance sometimes occurs: the wire storage drum 1, which is the driving force for wire feeding, inevitably has manufacturing and assembly tolerances. Accuracy tolerance caused dense longitudinal wave vibration superimposed on the electrode wire

[0007] 3. There is the defect of short service life of electrode wire: after long-term use by a large number of users, it is found that the service life of electrode wire on machine tools equipped with this mechanism is relatively short compared with ordinary machine tools with uncontrolled tension

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