A drive system for a mechanical press

Abstract

The invention discloses a driving system of a mechanical press. A power supply unit of electrical external power supply equipment is connected with a three-phase input reactor through an overpressure protection device. The output end of the three-phase input reactor is connected with the input end of an active network side module. The active network side module converts input alternating currents into direct currents required for the system and transmits the direct currents to an energy storage device. The output end of the energy storage device is connected with the input end of a motor driving device, and the energy storage device supplies energy to the motor driving device. The motor driving device realizes precise closed-loop control over a direct drive motor according to pulse signals provided by an upper computer. According to the system, the active network side module is adopted as a network side interface of the driving system, the power for supplementing energy to driving equipment from a power grid at the front end can be limited, network side peak currents brought by motor overload is avoided, and the network side capacity of the front end of the driving equipment is reduced. The minimum working voltage amplitude of a busbar can be ensured reliably, a working point required for work of the motor is guaranteed, and then the stability of equipment performance of the press is guaranteed.

Description

Technical field [0001] The invention relates to a drive system of a mechanical press. Background technique [0002] Sheet metal forming equipment is widely used in the production of plate and shell parts in the fields of automobiles, aerospace, electronics, communications and household appliances. There are many varieties and quantities, of which mechanical presses are the most common. Traditional mechanical presses have the advantages of low cost and high reliability, but the modern manufacturing industry puts forward higher and higher requirements for the diversification and individualization of products. Different products and processes have large differences in the speed requirements of the slider. . Traditional mechanical presses mostly use ordinary asynchronous motors as power sources, fixed transmission ratio mechanisms to form a transmission system, and single-degree-of-freedom variable transmission ratio mechanisms such as cams and connecting rods as actuators. The inpu...

AI Technical Summary

Problems solved by technology

Capacitive energy storage has fast charging and discharging speed, high conversion efficiency, and simple control, but due to its low energy storage density, the same energy storage requires higher cost and space when using capacitors

Although the overall cost of flywheel energy storage is lower than that of capacitor energy storage, its charging and discharging speed and conversion efficiency are lower than those of capacitor energy storage, and it requires complex control algorithms and control systems

[0005] As the core control system of the press, the AC servo drive system is also developing continuously. At present, the rectification part of the AC servo system that is widely used mostly uses diodes for uncontrolled rectification. Its shortcomings mainly include four aspects: (1) Press At the moment of stamping the workpiece, the motor runs at the maximum overload power instantaneously, which will inevitably cause the front-end grid side current impact of the driving equipment, which may cause accidents such as tripping, fuse blowing, etc., and may even affect the power grid of the factory area, causing other equipment to fail to operate normally

To avoid the above problems, the capacity of the front-end grid side of the drive equipment can only be greatly expanded, which will not only bring about a sharp increase in cost, but also the approval of power distribution capacity may not be passed

(2) When the motor is overloaded, the bus voltage drops continuously. When the bus voltage drops to a certain value, the motor will not be able to work at the required operating point, and the performance of the compressor equipment will be greatly reduced.

(3) The power factor of the system is low, which increases the capacity of the grid side, and at the same time, the harmonic content of the grid side is high, causing great pollution to the grid and affecting the normal operation of other equipment

(4) Since the bus voltage is uncontrollable, it is determined by the external power supply unit, and it is relatively close to the voltage amplitude required by the minimum operating point of the motor. operating point, the number of capacitors needs to be greatly increased, which greatly increases the cost of the system

However, there are also the following disadvantages: this driver uses diodes for uncontrolled rectification, and the bus voltage is affected by grid-side voltage fluctuations. The normal value is about 537VDC. Although the capacity of the capacitor is increased for expansion, the motor runs at the maximum overload power instantaneously when the press presses the workpiece. , it will inevitably cause the front-end grid side current impact of the drive equipment, which may cause accidents such as tripping and fuse blowing, and may even affect the power grid in the factory area, causing other equipment to fail to operate normally. If the distribution capacity is increased, the approval may not be possible. risk of passing

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