CN202771888U - Demagnetization control device of machine tool workpiece - Google Patents
Demagnetization control device of machine tool workpiece Download PDFInfo
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- CN202771888U CN202771888U CN 201220401147 CN201220401147U CN202771888U CN 202771888 U CN202771888 U CN 202771888U CN 201220401147 CN201220401147 CN 201220401147 CN 201220401147 U CN201220401147 U CN 201220401147U CN 202771888 U CN202771888 U CN 202771888U
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- demagnetization
- control device
- magnet exciting
- exciting coil
- machine tool
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Abstract
The utility model discloses a demagnetization control device of a machine tool workpiece. The demagnetization control device of the machine tool workpiece comprises a power source input end and a power source output end. The power source input end is electrically connected with a voltage transformation rectification stabilivolt circuit, and an output end of the voltage transformation rectification stabilivolt circuit is outputted to an H bridge inverter circuit through a direct current (DC)/DC boost circuit and acts as a direct current power source of the H bridge inverter circuit. The demagnetization control device of the machine tool workpiece further comprises a control loop which is composed of a digital signal processor, and the control loop collects information of a magnet exciting coil through an analog-digital (AD) converter, generates a pulse-width modulation (PMW) wave according to a calculated equivalent time constant of the magnet exciting coil, and controls rotating and conduction of a switch tube of the H bridge inverter circuit to generate demagnetization voltage with amplitude attenuation and adjustable polarity. A parameter identification technology is adopted by the demagnetization control device of the machine tool workpiece, so that a polarity moment which changes the demagnetization voltage exerted on two ends of the magnet exciting coil can be autonomously confirmed, and demagnetization efficiency is greatly improved. Simultaneously, a DC/DC conversion technology is used, so that the demagnetization control device of the machine tool workpiece can be applied to various to-be-demagnetization devices and lowers difficulty of operation and setting of equipment.
Description
Technical field
The utility model relates to the demagnetization field, relates in particular to a kind of Machinetool workpiece demagnetization control device.
Background technology
In mechanical processing process, magnetizing with demagnetizing to the magnechuck of clamping workpiece to be processed is a secondary process link that often runs into.Take surface grinding machine as example, this equipment is a kind of with magnechuck absorption workpiece, workpiece is carried out the equipment of flat surface grinding by emery wheel.The operation principle of magnechuck is exactly ampere circuital law famous in the Theory of Electromagnetic Field: ∫ Hdl=Jds+ D/ t.When needs magnechuck absorption workpiece to be processed, can apply exciting voltage at the magnet exciting coil two ends of magnechuck, produce exciting current, thereby produce the magnetic field of absorption workpiece to be processed, this process process that magnetizes exactly.After the course of processing finished, in the time of the workpiece that processes need to being disassembled from sucker, it was inadequate only eliminating exciting current.Known, ferromagnetic material has hysteresis, therefore eliminates exciting current, still has remanent magnetism and exist in ferromagnetic material, so that workpiece is difficult to dismounting.Just need to demagnetize to magnechuck this moment, with counteracting remanent magnetism to the absorption affinity of completion of processing workpiece, this process process of demagnetizing exactly.
The demagnetization control device of domestic existing magnechuck substantially all adopts the direct current reversing damped method at present, and the direct current reversing damped method makes the electric current by loading coil decay to gradually zero, thereby demagnetizes by constantly changing the size and Orientation of exciting voltage.The basic structure of these demagnetization control device all adopts the PWM ripple to drive the H bridge inverter circuit that is made of controlled tr tube, as shown in Figure 1.In Fig. 1, when Q1, Q4 pipe conducting Q2, Q3 cut-off, the electric current in the middle of the inductance L flows through from left to right; When Q2, Q3 pipe conducting Q1, Q4 cut-off, the electric current in the middle of the inductance L flows through from right to left, therefore is added in the height of Q1, Q2, Q3, Q4 gate pole logic level by change, can change the direction of exciting current.Change when being added in PWM ripple duty ratio, can change the size of DC power supply U among Fig. 1, thus the size of control exciting current.
From the Circuit theory angle, magnechuck can be considered inductive load.When adopting the direct current reversing damped method to demagnetize because the electric current in the coil decays, thereby so that magnetic field constantly decay.According to Faraday's electromagnetic induction law, the magnetic field of decay will induce induced electromotive force at the coil two ends, and the size of induced electromotive force and coil inductance are directly proportional with the rate of change of electric current.Therefore must be noted that when adopting the direct current reversing damped method to demagnetize: the reverse voltage that is added in the magnet exciting coil two ends should the current attenuation in coil be applied to the coil two ends again after zero, otherwise induced electromotive force will with the reverse voltage series aiding connection, cause the electric current in the circuit excessive, might cause damage to the element in the circuit.By Circuit theory as can be known, the electric current in the inductance will decay to zero substantially after through 3 to 5 times of time constants, so should whenever at the coil two ends apply back-pressure one time through 3 to 5 times of time constants for demagnetizer.For inductance element, inductance value and the resistance of its time constant and circuit are relevant, and the time interval that therefore wants to determine to apply back-pressure must be known the relevant parameter of circuit.But for different magnechucks, its inductance and resistance value are all not identical, for this reason, can only determine according to maximum in order to ensure the safety of circuit, thereby cause whole demagnetization process time elongated, and demagnetization efficiency is low.
For reliable demagnetization, exciting current decays to zero when guaranteeing to commutate at every turn, also will make the commutation number of times must be abundant, and each attenuation amplitude is as far as possible little.Therefore, in demagnetization operation, controller exports that one group of duty ratio progressively diminishes, the square wave sequence of positive and negative alternating polarity, until the duty ratio of square wave approaches zero.Fig. 3 is the current-voltage waveform figure that adopts the inductance coil of prior art.Among the figure, duty ratio constantly reduces, until current attenuation is zero to approaching, so each time of afterflow is also shorter and shorter, but each time of afterflow all is Td, has caused the very big reduction of efficient.
The utility model content
The technical problems to be solved in the utility model is: provide a kind of and can adapt to different magnechucks, automatically adjust the Machinetool workpiece demagnetization control device that applies demagnetization anti-pressure time and exciting voltage.
To achieve these goals, the technical solution adopted in the utility model is: a kind of Machinetool workpiece demagnetization control device, comprise power input and power output end, power input and transformation regulator rectifier circuit Electricity Federation, the output of transformation regulator rectifier circuit is depressed into the H bridge inverter circuit through DC/DC translation circuit output DC; Also comprise the control loop that is consisted of by digital signal processor, control loop gathers the information of magnet exciting coil by AD converter, and according to the magnet exciting coil equivalent time constant generation PWM ripple that calculates, the PWM ripple exports the DC/DC translation circuit to by the output of digital signal processor, the by turns conducting of simultaneously PWM ripple control H bridge inverter circuit switching tube is to produce amplitude fading, demagnetization voltage that polarity is adjustable.
Digital signal processor adopts BF531.
The beneficial effect that the utility model brings is: owing to having adopted DC/DC converter technique and parameter identification technique, can be according to the difference of actual magnet exciting coil driving voltage, change the output of DC/DC module, so that control device can adapt to the magnechuck of various models automatically, need not for different magnechucks the adjusting of time of demagnetizing the difficulty that has reduced equipment operating and adjusted.Use the method for correlation analysis, demagnetizer magnet exciting coil equivalent time constant is treated in identification, can accurately control the moment that magnet exciting coil is applied back-pressure, guarantees to carry out the change of current under the magnet exciting coil current attenuation is zero condition, reduce the risk of component wear, improved greatly demagnetization efficiency.
Description of drawings
Fig. 1 is the H bridge inverter circuit that is made of controlled tr tube;
Fig. 2 is theory diagram of the present utility model;
Fig. 3 is that the magnet exciting coil electric current and voltage changed schematic diagram when the demagnetization control device demagnetized to magnechuck in the prior art;
Fig. 4 is that magnechuck magnet exciting coil electric current and voltage changes schematic diagram in the utility model.
Embodiment
The utility model is described in further detail below in conjunction with drawings and the specific embodiments.
The utility model is introduced parameter identification technique and DC/DC converter technique in the electromagnetic chuck controller design, as shown in Figure 2, comprise power input and power output end, power input and transformation regulator rectifier circuit Electricity Federation, the output of transformation regulator rectifier circuit is depressed into the H bridge inverter circuit through DC/DC translation circuit output DC.Also comprise the control loop that is consisted of by digital signal processor; Control loop gathers the information of magnet exciting coil by AD converter, and according to the magnet exciting coil equivalent time constant generation PWM ripple that calculates, the PWM ripple exports the DC/DC translation circuit to by the output of digital signal processor, the PWM ripple exports the H bridge inverter circuit to simultaneously, the by turns conducting of control H bridge inverter circuit switching tube is to produce amplitude fading, demagnetization voltage that polarity is adjustable.Wherein, control loop adopts the DSP(digital signal processor), electromagnetic chuck controller hardware is based on the BF531DSP of ADI company in this example, utilize the high-speed computation ability of DSP device, adopt the method for correlation analysis that identification is carried out in the impulse response of magnechuck magnet exciting coil, thereby determine its equivalent time constant.In the situation that time constant is definite, only needs to apply back-pressure through 3-5 times of time constant to magnet exciting coil according to Circuit theory and get final product.
The step of utilizing this demagnetization control device that electromagnetic chuck of grinder is demagnetized:
(1) according to the rated operational voltage of magnet exciting coil, the DC/DC link in the controller is set, to satisfy the requirement of magnet exciting coil rated voltage.
(2) produce the required PRBS(pseudo-random binary sequence of parameter identification that is applied on the magnechuck magnet exciting coil by BF531 DSP) signal, utilize AD that the electric current in the magnet exciting coil is sampled.
The inputoutput data of the magnechuck magnet exciting coil that (3) obtains according to second step adopts the method for correlation analysis that the magnet exciting coil equivalent time constant is carried out identification.
(4) utilize the timer conter of BF531 DSP inside to produce the required PWM ripple of demagnetization, be 3-5 times of time constant the blanking time of adjacent PWM ripple, automatically determined by identification result the blanking time that namely applies back-pressure.
(5) the PWM ripple is applied to the magnet exciting coil two ends through the H bridge inverter circuit, and magnechuck is demagnetized.
Because the corresponding exciting voltage of different magnechuck magnet exciting coils is different, use for this reason the DC/DC converter technique with the 5V DC converting to nominal drive voltage corresponding to magnechuck magnet exciting coil, improve the adaptability of demagnetization control device.The method that the DC/DC link is set is the maximum that the magnet exciting coil two ends apply demagnetization voltage when setting demagnetization by interactive man-machine interface, and demagnetization voltage will take this voltage as benchmark, progressively decay to zero.Concrete circuit structure is DC/DC boost booster circuit.
Wherein, the method for utilizing correlation analysis method the magnet exciting coil equivalent time constant to be carried out identification is exactly the identification to the coil pulse response in essence, and its theoretical foundation is exactly famous Wiener-Hopf equation:
R in the formula
XY(t): the cross-correlation function of magnet exciting coil both end voltage and exciting current;
R
XX(t): the auto-correlation function of magnet exciting coil both end voltage;
G (t): the impulse response of magnet exciting coil;
When the magnet exciting coil both end voltage is the PRBS signal, because the auto-correlation function R of PRBS signal
XX(t)=and δ (t), at this moment, the Wiener-Hopf equation becomes R
XY(t)=and g (t), the cross-correlation function that namely only need calculate magnet exciting coil both end voltage and exciting current just can draw the impulse response g (t) of magnet exciting coil, just can directly determine system's equivalent time constant by g (t).
Adopt the electric current and voltage schematic diagram of magnechuck magnet exciting coil in the demagnetization process of this control method as shown in Figure 4.Switching tube Q1 when initial, the Q4 conducting; According to the duty ratio of initial setting, t1 controls two switching tube Q1 of a branch road constantly, Q4 turn-offs, owing to losing power supply, inductance coil begins discharge, and the electric current in the coil constantly reduces, finish through 3-5 times of time constant discharge, electric current drops to zero, actuating switch pipe Q2 immediately, Q3, then load voltage and electric current are all reverse, and electric current begins to increase.Comparison diagram 3 and Fig. 4 can find out easily, under PWM period of wave constant prerequisite, use this device significantly to shorten the demagnetization time, and owing in this device, having used parameter identification method, therefore the level of intelligence of controller significantly improves, but the various magnechucks of self adaptation need not the demagnetization time is manually adjusted.The demagnetization time of adopting this demagnetizing method is 1/3rd of traditional demagnetization time, Effective Raise demagnetization efficiency.
The above, it only is better embodiment of the present utility model, be not that the utility model is done any pro forma restriction, any those skilled in the art may utilize the technical scheme of above-mentioned announcement to be changed or be modified to the equivalent embodiment of equivalent variations, but every technical solutions of the utility model content that do not break away from, any simple modification, equivalent variations and modification according to technical spirit of the present utility model is done above-mentioned embodiment all still belong in the scope of technical solutions of the utility model.
Claims (2)
1. Machinetool workpiece demagnetization control device, comprise power input and power output end, power input and transformation regulator rectifier circuit Electricity Federation is characterized in that: the output of transformation regulator rectifier circuit is depressed into the H bridge inverter circuit through DC/DC translation circuit output DC; Also comprise the control loop that is consisted of by digital signal processor, control loop gathers the information of magnet exciting coil by AD converter, and according to the magnet exciting coil equivalent time constant generation PWM ripple that calculates, the PWM ripple exports the DC/DC translation circuit to by the output of digital signal processor, the by turns conducting of simultaneously PWM ripple control H bridge inverter circuit switching tube is to produce amplitude fading, demagnetization voltage that polarity is adjustable.
2. a kind of Machinetool workpiece demagnetization control device according to claim 1 is characterized in that: described digital signal processor employing BF531.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220401147 CN202771888U (en) | 2012-08-14 | 2012-08-14 | Demagnetization control device of machine tool workpiece |
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| CN 201220401147 CN202771888U (en) | 2012-08-14 | 2012-08-14 | Demagnetization control device of machine tool workpiece |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102832010A (en) * | 2012-08-14 | 2012-12-19 | 河南科技大学 | Machine tool workpiece demagnetization control device and method |
| CN103177847A (en) * | 2013-04-10 | 2013-06-26 | 国家电网公司 | Transformer demagnetization device |
| CN106451358A (en) * | 2016-10-13 | 2017-02-22 | 湘潭电机股份有限公司 | IGBT de-excitation method |
| CN109192437A (en) * | 2018-09-27 | 2019-01-11 | 南京迪威尔高端制造股份有限公司 | A kind of three phase full wave rectification ultralow frequency demagnetizing method |
| CN114944262A (en) * | 2022-07-25 | 2022-08-26 | 宁波兴隆磁性技术有限公司 | Direct-current constant-voltage magnetizing and demagnetizing control method |
-
2012
- 2012-08-14 CN CN 201220401147 patent/CN202771888U/en not_active Expired - Fee Related
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102832010A (en) * | 2012-08-14 | 2012-12-19 | 河南科技大学 | Machine tool workpiece demagnetization control device and method |
| CN102832010B (en) * | 2012-08-14 | 2015-02-04 | 河南科技大学 | Machine tool workpiece demagnetization control device and method |
| CN103177847A (en) * | 2013-04-10 | 2013-06-26 | 国家电网公司 | Transformer demagnetization device |
| CN103177847B (en) * | 2013-04-10 | 2016-08-03 | 国家电网公司 | transformer demagnetization device |
| CN106451358A (en) * | 2016-10-13 | 2017-02-22 | 湘潭电机股份有限公司 | IGBT de-excitation method |
| CN109192437A (en) * | 2018-09-27 | 2019-01-11 | 南京迪威尔高端制造股份有限公司 | A kind of three phase full wave rectification ultralow frequency demagnetizing method |
| CN114944262A (en) * | 2022-07-25 | 2022-08-26 | 宁波兴隆磁性技术有限公司 | Direct-current constant-voltage magnetizing and demagnetizing control method |
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Granted publication date: 20130306 Termination date: 20150814 |
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| EXPY | Termination of patent right or utility model |