Variable-speed circumferential low-stress bending fatigue crack precise blanking machine and blanking method thereof

Abstract

The invention discloses a variable-speed circumferential low-stress bending fatigue crack precise blanking machine and a blanking method of the variable-speed circumferential low-stress bending fatigue crack precise blanking machine. The variable-speed circumferential low-stress bending fatigue crack precise blanking machine comprises a variable-frequency motor, a large belt pulley, a V-shaped belt, a small belt pulley, a two-stage gear accelerator, a high-speed main shaft, a sliding rail supporting seat, a screw compression spring, a columnar hammer head, a feeding sleeve, a ball guide bushing, metal bars, a clamping hand, a clamping cylinder, a feeding cylinder, a hydraulic clamping feeding mechanism support, a machine body, a seat plate, a servo motor, a speed reducer, a coupler, a ball screw supporting seat, a screw, a nut, a ball screw, a deep groove ball bearing and a key. The variable-speed circumferential low-stress bending fatigue crack precise blanking machine is high in geometric precision of blanking workbanks, free of corner collapse and radial deformation, perpendicular and smooth in fracture section, few in burrs, and high in use ratio of material. The stress concentration effect, the resonance effect and the bending fatigue of an annular V-shaped groove are utilized to enable the critical value of the impact speed of vibration on the metal bars to be lower than the critical value of the speed in the high-speed shearing process, and the blanking machine is applicable to precise blanking of the metal bars of different materials.

Description

technical field [0001] The invention relates to a variable-speed circumferential low-stress bending fatigue fracture precision blanking machine and a blanking method thereof, which belong to the technical field of mechanical processing equipment. Background technique [0002] In the metal products and machinery manufacturing industry, blanking is the first process of metal forming, which is widely used in the material preparation process of die forging, cold extrusion, metal chain pins, bolts, rolling bearing rollers, auto parts production, etc. . At present, tens of millions of tons of bars need to be precisely blanked each year in China. The annual demand for motorcycle chains alone reaches 80 million meters, and the demand for internal combustion engine piston pins reaches 20 million. [0003] Low-stress blanking is to apply crack technology to bar blanking. First, a circumferential crack is artificially prefabricated on the surface of the bar, and then a certain externa...

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Problems solved by technology

[0004] However, the current low-stress bending blanking method has the following shortcomings: (1) The crack initiation time is long, resulting in a long total blanking time and unstable

(3) In the stage of crack propagation, the external force on the bar is the impact vibration force that has not realized the closed-loop control, resulting in the instability of the overall section quality

However, due to the obvious uneven force on each fracture (damage) point at the same radius on the bar section, the crack growth speed in the circumferential direction is not synchronized, and then fracture zones with different shapes are produced; (4) The crack growth stage adopts impact Low-stress blanking of the bar by loading or intermittent blowing is beneficial to reduce the external force on the bar, but it is difficult to control the crack growth at this time, the inertia effect of the moving mold is not easy to disappear, and the blanking time is unstable

If the initial vibration force is small, the crack may not expand or expand slowly, resulting in low productivity; if the initial vibration force is large, the bar may be broken due to the instantaneous expansion of the crack, resulting in poor blanking quality, high vibration and noise

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