CN101249637A - A magnetorheological polishing liquid circulation device that can stabilize the performance of the polishing liquid for a long time - Google Patents

Abstract

A magneto-rheological polishing liquid circulation device that can stabilize the performance of the polishing liquid for a long time. Its liquid mixing tank is connected to the water tank through a metering pump, and the cooler is connected to the liquid mixing tank through a cooling pipeline; The liquid mixing tank, electromagnetic flowmeter, nozzle, recovery device and recovery pump form a polishing liquid circulation loop, and the liquid mixing tank and electromagnetic flowmeter connected in sequence through the non-polishing circulation pipeline form a non-polishing circulation loop, and the polishing liquid circulation loop and the non-polishing The circulation loop is connected in parallel and a switching control valve is provided at the parallel connection of the two. A helical coil is wound outside a section of pipeline between the liquid mixing tank and the switching control valve; the electromagnetic flowmeter and the helical coil are connected to the input end of the computer, and its control The output ends are respectively connected with the switching control valve, the cooling machine, the power pump and the metering pump. The invention has the advantages of high control precision, good stability, etc., and can provide cheap, reliable and stable magnetorheological polishing liquid for magnetorheological polishing processing for a long time.

Description

A magnetorheological polishing liquid circulation device that can stabilize the performance of the polishing liquid for a long time

technical field

The invention mainly relates to the technical field of magnetorheological polishing, in particular to a magnetorheological polishing fluid circulation device capable of stabilizing the performance of the polishing fluid for a long time.

Background technique

Deterministic magnetorheological polishing technology is an advanced optical manufacturing method proposed by combining electromagnetics, fluid dynamics, and analytical chemistry. It is one of the effective means of processing aspheric optical parts. It can obtain high-precision optical surfaces At the same time, it ensures good surface processing quality, small workpiece subsurface damage and high processing efficiency, so as to meet the processing requirements of modern optics for optical parts. The deterministic magnetorheological polishing technology uses the rheology of the magnetorheological polishing fluid in the magnetic field to polish the workpiece. The magnetorheological polishing fluid is brought into the polishing area by the polishing theory cycle. Under the action of the high-intensity gradient magnetic field in the area, it becomes The viscoplastic Bingham medium hardens and becomes more viscous, forming a "flexible polishing mold" with a certain shape (the magnetorheological fluid forms raised ribbons in the magnetic field), when the "flexible polishing mold" flows through the workpiece and the polishing When there is a small gap formed by the disc, a large shear force will be generated on the surface of the workpiece, and the material on the surface of the workpiece will be removed.

To achieve deterministic magnetorheological polishing, the key is to be able to maintain the stability of the circulating magnetorheological polishing fluid for a long time, thereby ensuring the consistency of the removal function model of magnetorheological polishing. Only in this way can the optical Accurate removal of part surfaces. Magnetorheological polishing liquid is an important carrier for deterministic magnetorheological polishing of optical parts. It realizes the mechanical and chemical comprehensive removal of the surface of optical parts by carrying polishing particles. The stability of its performance directly affects the processing quality of optical parts. The timeliness of its cycle determines the processing time of optical parts. The development of modern science and technology has put forward higher requirements for the processing caliber, processing precision and processing quality of optical processing. These requirements make optical processing present the characteristics of long processing cycle, many convergence times, and intermittent repetition. As an advanced optical manufacturing method, deterministic magnetorheological polishing must effectively control the characteristics of the circulating magnetorheological polishing fluid in order to meet the requirements of modern optical processing. Regardless of the performance of the magnetorheological fluid itself, in the process of magnetorheological polishing of optical parts, the removal characteristics of magnetorheological polishing fluid on optical parts are as follows: the flow rate of magnetorheological polishing fluid, the magnetorheological The magnetic particle content of the polishing fluid. By controlling the flow stability of the magnetorheological polishing fluid, it can be ensured that the magnetorheological polishing fluid has a shape-stable removal function; by controlling the stability of the magnetic particle content in the magnetorheological polishing fluid, the magnetorheological Polishing has a stable removal capability, enabling deterministic and high-precision removal of optical materials.

The Center for Optics Manufacturing (COM) at the University of Rochester in the United States was the first to apply magnetorheological fluids to deterministic magnetorheological polishing abroad. COM started to establish a magnetorheological polishing experimental system in 1993, and has developed several generations of commercial machine tools for deterministic magnetorheological polishing so far. In 2001, COM applied for the patent (USP862245) of the magnetorheological fluid transmission system by measuring the pressure loss and flow rate to calculate and control the viscosity of the magnetorheological fluid, so as to realize the stability control of the magnetorheological fluid performance, but its The stable control of the performance of the magnetorheological polishing fluid is only limited to the processing state, so it is difficult to carry out long-term intermittent repeated processing, and the measurement of the viscosity of the magnetorheological polishing fluid requires simultaneous detection of the pressure and flow of the liquid, pressure and flow The error will be introduced into the viscosity, so the accuracy is limited. In China, most of the research on magnetorheological polishing technology is still in its infancy, so many research institutes are relatively simple to control the performance of magnetorheological polishing fluid in the process of using magnetorheological polishing, or even do not implement effective control. . In its patent (Patent No.: ZL03153996.3), Tsinghua University provides an electromagnetic polishing head that can be rotated and rotated for magnetorheological polishing. During the processing, the magnetorheological polishing fluid does not participate in the circulation, so there is no need for magneto-rheological polishing. The properties of rheological polishing fluids are controlled. This method of processing without controlling the performance of the magnetorheological fluid cannot take away the processing heat and grinding debris. With the evaporation and deterioration of the moisture in the magnetorheological polishing fluid during processing, the performance of the magnetorheological polishing fluid changes, resulting in the inability to achieve deterministic and precise magnetorheological polishing. During the research process of magnetorheological polishing technology, Harbin Institute of Technology established a circulation device for controlling the stable performance of magnetorheological polishing fluid in processing. The recycling of the polishing liquid is realized, but because it also uses the pressure loss and flow rate to monitor the liquid viscosity, and its device uses a diaphragm pump with a large pulsation as the power source of the circulation system, the ejection of the magnetorheological polishing liquid is unstable and continuous; The recovery device uses the copper sheet to contact the polishing wheel to block the flow of the magnetorheological polishing fluid for recycling, which is easy to rub and scratch the surface of the polishing wheel, affecting the surface quality and roundness of the polishing wheel; the control system only controls the viscosity of the magnetorheological polishing fluid. The closed-loop control does not control the flow rate of the magnetorheological polishing fluid that affects the stability of the processing process during the processing process, and the temperature of the magnetorheological polishing fluid in the cycle is not controlled, so it is difficult to be used for the modification and polishing of high-precision optical parts.

The existing method for stabilizing the performance of magnetorheological polishing fluid is usually to measure the pressure loss and liquid flow of magnetorheological polishing fluid along the way to calculate the viscosity of magnetorheological polishing fluid, and to stabilize the magnetorheological polishing fluid by controlling the viscosity of magnetorheological polishing fluid. The performance of the magnetorheological polishing fluid, this method is not only complicated, but also has a large error because the viscosity detection will be affected by the pressure measurement accuracy and the flow measurement accuracy at the same time. Moreover, the viscosity characteristic of the magnetorheological polishing fluid is to characterize the performance of the magnetorheological polishing fluid from the performance of the fluid, which is not directly related to the shear stress of the magnetorheological polishing fluid on the optical material in the polishing area in magnetorheological polishing. Therefore, it cannot fully reflect the material removal characteristics of the polishing fluid in magnetorheological polishing.

Contents of the invention

The problem to be solved by the present invention is that: aiming at the technical problems existing in the prior art, the present invention provides a simple and compact structure, low cost, high control precision, good stability, and can provide low-cost, Reliable and stable magnetorheological polishing fluid circulation device for magnetorheological polishing fluid that can stabilize the performance of the polishing fluid for a long time.

In order to solve the above-mentioned technical problems, the solution proposed by the present invention is: a magneto-rheological polishing liquid circulation device capable of stabilizing the performance of the polishing liquid for a long time, which is characterized in that it includes a liquid mixing tank connected by pipelines, a power pump, Electromagnetic flowmeter, nozzle, recovery device, recovery pump, cooler, water tank and computer, the power pump is connected to the liquid mixing tank, the liquid mixing tank is connected to the water tank through the metering pump, and the cooling machine is connected to the liquid mixing tank through the cooling pipeline ;The liquid mixing tank, electromagnetic flowmeter, nozzle, recovery device and recovery pump connected in sequence through the polishing circulation pipeline form a polishing liquid circulation loop, and the liquid mixing tank and electromagnetic flowmeter connected in sequence through a non-polishing circulation pipeline form a non-polishing circulation The loop, the polishing liquid circulation loop and the non-polishing circulation loop are connected in parallel and a switching control valve is provided at the parallel connection of the two, and a helical coil is wound outside a section of the pipeline between the liquid mixing tank and the switching control valve; the electromagnetic flowmeter and the helical coil It is connected with the input end of the computer, and the control output end of the computer is respectively connected with the switching control valve, the cooling machine, the power pump and the metering pump.

The liquid mixing tank includes a liquid mixing tank body and a cooling water tank, an inner partition is arranged in the liquid mixing tank body, a cooling water tank is formed between the inner partition and the outer wall of the liquid mixing tank, and a cooling water tank is formed on the liquid mixing tank body. There is a return port connected with the recovery device, and the cooling water tank is provided with a cooling water inlet and a cooling water outlet connected with the cooling pipeline.

The driving motor of the power pump is installed on the tank body of the liquid mixing tank, the power pump shaft connected with the driving motor is located in the tank body of the liquid mixing tank, and one or more stirring blades are installed on the power pump shaft.

The recovery device comprises a recovery device seat, a permanent magnet strip and a recovery device absorption tube, the inside of the recovery device seat is hollow to form a recovery device liquid storage room, and a recovery device absorption tube is installed in the recovery device liquid storage room, and the recovery device absorption tube Connected with the recovery pump, the permanent magnetic strip is arranged in a circular shape on the outer ring of the recovery device seat.

The nozzle includes a nozzle inner tube and a magnetic protective shell, and the nozzle inner tube is installed in the magnetic protective shell and communicated with the polishing circulation pipeline.

The computer is connected with the power pump through a frequency converter.

Compared with the prior art, the present invention has the advantages of:

1. The magnetorheological polishing fluid circulation device of the present invention, which can stabilize the performance of the polishing fluid for a long time, improves the performance of the magnetorheological polishing fluid by comprehensively controlling the flow rate, magnetic particle content and temperature of the magnetorheological polishing fluid in the circulation The long-term stability provides favorable support for high-precision optical processing. By adding a cooling device that can control the temperature in the liquid mixing tank, the temperature stability of the magnetorheological polishing fluid in circulation is maintained, so that the performance of the magnetorheological polishing fluid eliminates the influence of temperature fluctuations; through the circulation device The closed-loop control of the flow in the magneto-rheological polishing fluid can keep the flow rate of the magnetorheological polishing fluid stable, thereby ensuring the process stability in the magnetorheological polishing process; by adding a pipeline wound with a spiral coil, the inductance of the magnetorheological polishing fluid can be measured in real time value, according to the relationship between the magnetic particle content and the inductance, the magnetic particle content value of the magnetorheological polishing fluid is obtained, and the control is added during the cycle to keep the composition of the magnetorheological polishing fluid stable, thereby ensuring that the magnetorheological polishing fluid is in the The removal efficiency is constant under high intensity gradient magnetic field. Using the method of comprehensively controlling the temperature, flow rate and magnetic particle content, the characteristics of the magnetorheological polishing fluid during the magnetorheological polishing process are finally guaranteed to be constant, and the removal function model is consistent, which is a deterministic, high-precision and controllable magnetic flow Variable polishing provides a reliable guarantee;

2. The magnetorheological polishing fluid circulation device of the present invention, which can stabilize the performance of the polishing fluid for a long time, provides two modes of long-term stable performance of the magnetorheological polishing fluid: magnetorheological polishing fluid polishing circulation mode and magnetorheological polishing fluid Non-polish cycle mode. Switching the solenoid valve through computer control can realize the free switching of the two circulation modes. When performing optical processing, the magnetorheological polishing fluid can be used to polish the circulation mode; Polishing cycle mode, which can meet the characteristics of optical processing, especially large-caliber and high-precision optical processing, with long processing cycle, many convergence times, and intermittent repetition, and maintain the long-term stability of the performance of magnetorheological polishing fluid;

3. The magnetorheological polishing fluid circulation device of the present invention can stabilize the performance of the polishing fluid for a long time, and its recovery device utilizes the permanent magnetic strip with a gap in the ring to generate a magnetic field to block the continuous flow of the magnetorheological polishing fluid, forming a brush-like The "flexible scraper" enables the magnetorheological polishing fluid to be recovered smoothly, avoiding the disadvantages of traditional collectors using copper sheets to block the magnetorheological polishing fluid, causing friction and scratching the polishing disc, and better maintaining the roundness of the polishing wheel Accuracy and precision; the recovery device is designed into a cup shape, which reduces the loss of magnetorheological polishing fluid, makes the recovery cleaner, and keeps the composition of magnetorheological polishing fluid stable; the installation of the recovery device is not placed on the polishing wheel in an ordinary installation mode Instead, it is placed above the polishing wheel, which not only saves the installation space of the inverted polishing wheel, but also facilitates the magnetorheological polishing of large-diameter and high-steep optical parts;

4. The magnetorheological polishing fluid circulation device of the present invention can stabilize the performance of the polishing fluid for a long time. The pressure sensor is removed from the nozzle, so it is not only more compact in structure and simpler in shape, but also reduces the flow of magnetorheological polishing fluid through the nozzle. The resulting pressure loss makes the ejected magnetorheological polishing fluid flow more concentrated and dense;

5. The magnetorheological polishing liquid circulation device of the present invention, which can stabilize the performance of the polishing liquid for a long time, uses a frequency converter to control the speed of the centrifugal pump, which is simple and convenient, and is easy to realize the closed-loop control of the flow rate. By detecting the flow rate of the magnetorheological polishing liquid in real time, and then controlling the speed of the centrifugal pump according to the difference with the set flow rate, the pulsation of the peristaltic pump, the cutting of the magnetorheological "ribbon" into the workpiece, and the The out-of-roundness of the polishing wheel and the flow fluctuation caused by poor recovery improve the stability of the polishing process parameters and the removal function model.

Description of drawings

Fig. 1 is the overall structural diagram of the long-time stable magnetorheological polishing liquid performance device of the present invention;

Fig. 2 is a schematic diagram of the nozzle structure of the present invention;

Fig. 3 is a structural schematic diagram of an inverted recovery device of the present invention;

Fig. 4 is a schematic structural view of a liquid mixing tank of the present invention;

Fig. 5 is a long-time stable magnetorheological polishing fluid performance control flow chart of the present invention;

Fig. 6 is the control curve of the flow rate of the magnetorheological polishing fluid and the content of magnetic particles in the present invention.

illustration

1. Polishing wheel 2. Computer

3. Liquid mixing tank 4. Power pump

5. Metering pump 6. Water tank

7. Workpiece 8. Recovery pump

9. Electromagnetic flowmeter 10. Helical coil

11. Recovery device 12. Switching control valve

13. Cooling machine 14. Frequency converter

15. Nozzle 16. Cooling pipeline

17. Polishing circulation pipeline 18. Non-polishing circulation pipeline

19. Cable 20. Nozzle inner tube

21. Magnetic protective shell 22. Pipeline connection thread

23. Permanent magnetic strip 24. Liquid storage room of recovery device

25. Recovery device absorption pipe 26. Recovery device seat

27. Connecting pipe thread 28. Drive motor

29. Power pump shaft 30. Return port

31. Return pipe joint 32. Liquid mixing tank body

33. Stirring blade 34. Cooling water inlet

35. Power pump inlet 36. Cooling water tank

37. Power pump water channel 38. Cooling water outlet

39. Power pump outlet

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

As shown in Fig. 1, a kind of magnetorheological polishing liquid circulating device of the present invention can stabilize polishing liquid performance for a long time, it comprises the liquid mixing tank 3 that is connected by pipeline, power pump 4, electromagnetic flow meter 9, nozzle 15 , recovery device 11, recovery pump 8, cooling machine 13, water tank 6 and computer 2, power pump 4 is connected with liquid mixing tank 3, liquid mixing tank 3 is connected with water tank 6 through metering pump 5, cooling machine 13 is through cooling pipeline 16 It is connected with the liquid mixing tank 3; the liquid mixing tank 3, the electromagnetic flowmeter 9, the nozzle 15, the recovery device 11 and the recovery pump 8, which are connected in sequence through the polishing circulation pipeline 17, form a polishing liquid circulation loop, and pass through the non-polishing circulation pipeline 18 sequentially The connected liquid mixing tank 3 and the electromagnetic flowmeter 9 form a non-polishing circulation loop. The polishing liquid circulation loop and the non-polishing circulation loop are connected in parallel and a switching control valve 12 is provided at the parallel connection of the two. The connection between the liquid mixing tank 3 and the switching control valve 12 A helical coil 10 is wound on the outside of a section of pipeline between them; the electromagnetic flowmeter 9 and the helical coil 10 are connected to the input end of the computer 2, and the control output end of the computer 2 is respectively connected to the switching control valve 12, the cooling machine 13, the power pump 4 and the Metering pump 5 is connected. In a preferred embodiment, the computer 2 is connected to the power pump 4 through a frequency converter 14, the switching control valve 12 is a solenoid valve, and the recovery pump 8 is a peristaltic pump. By default, the solenoid valve is in the state of connecting the magnetorheological polishing fluid circulation pipeline 17, that is, the circulation device is in the magnetorheological polishing fluid polishing circulation mode. The solenoid valve is controlled by the computer 2. When the circulation device switches from the magnetorheological polishing liquid polishing circulation mode to the magnetorheological polishing liquid non-polishing circulation mode, the computer 2 gives the solenoid valve an on-off signal to control the solenoid valve to turn the magnetorheological polishing The liquid circulation line 17 is closed, and the magnetorheological polishing liquid circulation line 18 is connected simultaneously; otherwise, when the circulating device is to switch from the magnetorheological polishing liquid non-polishing cycle state to the magneto-rheological polishing liquid polishing cycle state, the computer 2. Also send an on-off signal to the solenoid valve to control the solenoid valve to close the magnetorheological polishing liquid circulation pipeline 18, and connect the magnetorheological polishing fluid circulation pipeline 17, so as to ensure that the magnetorheological polishing fluid is in the The polishing cycle state is used to perform magnetorheological polishing. These two working modes can provide consistent and stable magnetorheological polishing fluid for long-term intermittent magnetorheological polishing. In the magnetorheological polishing fluid polishing cycle mode, the centrifugal pump pumps out the magnetorheological polishing fluid in the liquid mixing tank 3, and the magnetorheological polishing fluid flows through the polishing circulation pipeline 17 through the pipeline wound with the helical coil 10, After the electromagnetic flowmeter 9 and the solenoid valve flow to the nozzle 15, the nozzle 15 sprays the magnetorheological polishing fluid onto the polishing wheel 1, and the polishing wheel 1 rotates to bring the magnetorheological polishing fluid into the processing area to remove the workpiece 5, and then With the rotation of the polishing wheel, it reaches the top of the polishing wheel, and then enters the inverted recovery device 11. The inverted recovery device is connected with a peristaltic pump, and the peristaltic pump pumps the magnetorheological polishing liquid to the In the liquid mixing tank, the magnetorheological polishing liquid in the magnetorheological polishing process can be recycled; in the non-polishing mode of the magnetorheological polishing liquid, the centrifugal pump 4 pumps the magnetorheological polishing liquid out of the liquid mixing tank 3 , pumped back into the liquid mixing tank 3 via the pipeline wound with the helical coil 10, the electromagnetic flowmeter 9, the solenoid valve and the non-polishing circulation pipeline 18, realizing the stable circulation of the magnetorheological polishing liquid in the non-polishing state.

Referring to FIG. 2 , in this embodiment, the nozzle 15 includes a nozzle inner tube 20 and a magnetic protection casing 21 , the nozzle inner tube 20 is installed in the magnetic protection casing 21 and communicates with the polishing circulation pipeline 17 . The nozzle 15 sprays the magnetorheological polishing liquid pumped by the centrifugal pump 4 onto the polishing wheel 1 in a certain shape, so as to provide continuous and stable magnetorheological polishing liquid for magnetorheological polishing. In order to prevent the nozzle inner tube 20 from being magnetized, thereby affecting the fluidity of the magnetorheological polishing fluid therein, the nozzle inner tube 20 is made of non-magnetic material, such as stainless steel. The inner tube 20 of the nozzle is installed in the magnetic protective shell 21, and the magnetic protective shell 21 is made of soft magnetic material, which can shield the magnetic interference introduced from the magnetic field generated by the electromagnet in the polishing wheel, so that the magnetorheological polishing liquid is in the inner tube 20 of the nozzle. free flow in. There is a pipeline connection thread 22 at the inlet of the nozzle 15 for connecting the nozzle 15 with the polishing circulation pipeline 17 of the magnetorheological fluid. Since the present invention obtains the content of magnetic particles in the magnetorheological polishing fluid by measuring the inductance value of the pipeline 10 wound with a helical coil, the stable control of the performance of the magnetorheological polishing fluid is realized. It is no longer necessary to measure the viscosity, so the structure of the nozzle 15 is more compact, and the length can be shortened accordingly, which not only saves the cost, but also reduces the pressure loss of the magnetorheological polishing fluid at the nozzle 15, so that the ejected magnetorheological The polishing liquid flow is more concentrated and compact, which is conducive to the stable formation of "polishing ribbon".

Referring to shown in Fig. 3, recovery device 11 comprises recovery device seat 26, permanent magnetic bar 23 and recovery device absorption tube 25, and the inside of recovery device seat 26 is hollow shape and forms recovery device liquid storage room 24, and recovery device liquid storage room 24 A recovery device absorption pipe 25 is installed, and the recovery device absorption pipe 25 is connected to the recovery pump 8 , and the permanent magnet strip 23 is arranged in a circular shape at the outer ring of the recovery device seat 26 . In this embodiment, the recovery device 11 adopts an inverted recovery device 11, which is a hollow cup-shaped container as a whole, and a ring-shaped permanent magnetic strip 23 is pasted on the outer ring of the recovery device seat 26. When the magnetorheological polishing liquid is brought from the nozzle 15 to the inverted recovery device 11 by the rotating polishing wheel, the magnetorheological polishing liquid hardens rapidly under the action of the permanent magnetic strip 23, thereby forming a flexible ring around the Around the recovery device seat 26, only the inner notch of the recovery device seat 26 flows down the space, so the magnetorheological polishing fluid enters the recovery device liquid storage room 24 under the extrusion of the flexible annular belt, and the recovery device stores A recovery device absorption pipe 25 is installed in the liquid room 24, which is connected to the peristaltic pump 8 responsible for recovery through the connecting pipe thread, so that the magnetorheological polishing liquid is sucked back to the liquid mixing tank by the peristaltic pump 8 through the recovery device absorption pipe 25 In 3, the continuous renewal of the magnetorheological polishing fluid is maintained.

Referring to shown in Figure 4, the liquid mixing tank 3 comprises a liquid mixing tank body 32 and a cooling water tank 36, an inner partition is provided in the liquid mixing tank body 32, and cooling is formed between the inner partition and the liquid mixing tank body 32 outer walls. The water tank 36 and the tank body 32 of the liquid mixing tank are provided with a return port 30 connected to the recovery device 11 , and the cooling water tank 36 is provided with a cooling water inlet 34 and a cooling water outlet 38 connected to the cooling pipeline 16 . The driving motor 28 of the power pump 4 is installed on the liquid mixing tank body 32, and the power pump pump shaft 29 connected with the driving motor 28 is positioned in the liquid mixing tank body 32, and one or more than one pump shafts are installed on the power pump pump shaft 29 Stirring blade 33 . In this embodiment, the power pump 4 adopts a centrifugal pump, which is fixed in the tank body 32 of the liquid mixing tank through a mounting hole, the cooling water tank 36 is a hollow part between the outer wall and the inner wall of the liquid mixing tank 3, and the cooling water inlet 34 is located in the liquid mixing tank 32. The lower part of the mixing tank body 32 is connected to the water outlet of the cooling machine 13 through a pipeline, and the constant temperature circulating cooling water enters the inside of the liquid mixing tank body 32 from the cooling water inlet 34 to cool the magnetorheological polishing liquid, and then It flows back to the cooling machine 13 through the cooling water outlet 38 . The tank body 32 of the liquid mixing tank is cylindrical in shape and made of non-magnetic material such as duralumin. The magnetorheological polishing liquid return port 30 is connected to the solenoid valve 12 through the return pipe joint 31, and the recovered magnetorheological polishing liquid enters the inside of the liquid mixing tank 3 through the magnetorheological polishing liquid return port 30, and in the liquid mixing tank 3, the drive The motor 28 drives the magnetorheological polishing liquid stirring blade 33 installed on the power pump pump shaft 29 to rotate, and the magnetorheological polishing liquid inside the liquid mixing tank 3 is fully stirred, which can prevent the magnetorheological polishing liquid from being trapped in the tank. of settlement. The fully stirred magnetorheological polishing liquid is pumped into the water channel 37 of the power pump through the inlet 35 of the power pump, then reaches the outlet 39 of the centrifugal pump, and finally enters the pipeline 10 connected with the helical coil, The continuous supply of magnetorheological polishing liquid is realized.

In the present invention, the control of the performance of the magnetorheological polishing fluid is composed of three parts: a temperature control mechanism, a flow control mechanism and a magnetic particle content control mechanism. Long-term stable control of variable polishing fluid performance.

The temperature control mechanism includes a cooling machine 13 and a cooling pipeline 16. The cooling machine 11 has a temperature control function, and it is connected with the electromagnet coil of the magnetic field generator and the liquid mixing tank 3 through the cooling pipeline 16. The cooling machine 11 pumps constant temperature water In the electromagnet coil and the liquid mixing tank 3, the magnetorheological polishing fluid in the circulation is cooled, and the temperature of the magnetorheological polishing fluid is kept stable at a certain constant value.

The flow control mechanism includes an electromagnetic flowmeter 9, a frequency converter 14 and a centrifugal pump. The computer 2 is connected to the electromagnetic flowmeter 9 through the cable 19. When the magnetorheological polishing fluid passes through the electromagnetic flowmeter 9, the electromagnetic flowmeter 9 can detect the flow of the magnetorheological polishing fluid in real time, and transmit the flow value through the cable 19. To the computer 2, the computer 2 compares the obtained actual flow value with the set flow value, and then the computer 2 uses a certain algorithm to obtain a control signal according to the difference between them and sends a control signal to the frequency converter 14, because The output end of the frequency converter 14 is connected to the centrifugal pump 4, so that the frequency converter 14 can control the increase or decrease of the rotational speed of the centrifugal pump 4, so that the flow rate of the magnetorheological polishing fluid can always be kept near a certain flow value set, satisfying The process requirements of magnetorheological polishing for flow stability.

The magnetic particle content control device includes a pipeline wound with a helical coil 10 , a metering pump 5 and a water tank 6 . Computer 2 is connected with helical coil 10 and metering pump 5 respectively by cable 19, and the inlet of metering pump 5 is connected with water tank 6 through polishing circulation pipeline 17, and its outlet is then connected to liquid mixing tank 3 through polishing circulation pipeline 17. The computer 2 monitors the magnetic particle content of the magnetorheological polishing liquid in real time through the cable 19. When the magnetic particle content in the magnetorheological polishing liquid becomes larger, the computer 2 sends a starting signal to the metering pump 5, so that the metering pump 2 starts to work, thereby Add water to the liquid mixing tank 3, and when adding water makes the magnetic particle content of the magnetorheological polishing liquid less than the set value, the computer 2 sends a stop signal to the metering pump 5 again, so that the metering pump 5 stops adding water, through such a real-time The closed-loop control keeps the content of magnetic particles in the magnetorheological polishing fluid stable.

The device of the present invention has two working modes: the magnetorheological polishing fluid polishing circulation mode and the magnetorheological polishing fluid non-polishing circulation mode. By controlling the performance of the magnetorheological polishing fluid in two working modes, the long-term stability of the performance of the magnetorheological polishing fluid is realized. For further understanding, the following is a detailed introduction to the performance of the long-term stable magnetorheological polishing fluid in the two types of schematic diagrams. Working principle in working mode.

Magnetorheological polishing fluid polishing cycle mode:

In the magnetorheological polishing liquid polishing circulation mode, the magnetorheological polishing liquid is added into the liquid mixing tank 3, and when the whole device starts to operate, the magnetorheological polishing liquid is pumped in from the liquid mixing tank 3 by the power pump 4 into the polishing circulation pipeline 17, and then the magnetorheological polishing fluid flows through the pipeline around the helical coil 10 and the electromagnetic flowmeter 9, and reaches the nozzle 15 through the switching control valve 12, and the magnetorheological polishing fluid is sprayed from the nozzle out to the surface of the rotating inverted polishing wheel 1, and as the polishing wheel 1 reaches the polishing area, the material is removed from the workpiece. After the removal is completed, the magnetorheological polishing liquid is brought to the top of the polishing wheel 1 with the rotation of the polishing wheel 1. The inverted recovery device 11 connected to the recovery pump 8 continuously recovers it, and the recovered magnetorheological polishing liquid returns to the liquid mixing tank 3 through the polishing circulation pipeline 17 and the switching control valve 12, thereby completing the magnetorheological polishing liquid. One cycle of polishing fluid in polishing cycle mode. Once the normal circulation flow of the magnetorheological polishing fluid is established, it is necessary to control the performance of the magnetorheological polishing fluid in real time to keep its performance stable, so as to perform magnetorheological polishing. In the process of controlling the performance of the magnetorheological polishing fluid, it is necessary to set the initial values of the temperature, flow rate and magnetic particle content of the magnetorheological polishing fluid. After setting their initial values, the temperature control mechanism and the flow control mechanism start to work. Fig. 5 has shown the flow chart of long-term performance stable control of magnetorheological polishing liquid, cooling machine 13 determines whether it works according to the actual temperature of magnetorheological polishing liquid and the comparative value of set temperature, if the actual temperature of magnetorheological polishing liquid If the temperature is higher than or lower than the set temperature, the cooling machine 13 starts to keep its temperature near the set temperature value by delivering circulating water with a set temperature value to the liquid mixing tank 3; at the same time, the computer 2 passes The electromagnetic flowmeter 9 measures the flow rate of the magnetorheological polishing fluid in real time and compares it with the set flow value. If the flow rate of the magnetorheological polishing fluid is too small, the computer 2 sends a control signal to the frequency converter 14, and the frequency converter 14 then controls the power. The pump 4 is accelerated to increase the actual flow rate to reach the set flow value; and if the flow rate of the magnetorheological polishing liquid is too large, the computer 2 sends a signal to the frequency converter to control the speed reduction of the power pump 4, so that the power pump 4 pumps The actual flow rate of the magnetorheological polishing fluid is reduced to keep consistent with the set flow value. When the temperature and flow rate of the magnetorheological polishing liquid are relatively stable, the fluctuation is less than 5%, and the magnetic particle content control system starts to play a role. The measured inductance value, the computer 2 calculates the obtained inductance value to obtain the magnetic particle content value in the magnetorheological polishing liquid, and compares it with the set value, if the magnetic particle content value of the magnetorheological polishing liquid is greater than the set value value, then the computer 2 sends a control signal to the metering pump 5 connected to the water tank 6 through the cable 19, so that the metering pump 5 is turned on to add water to the liquid mixing tank 3, and the computer 2 continuously detects the magnetic particles of the current magnetorheological polishing liquid content, once the magnetic particle content is less than the set value, the computer 2 will send a shutdown signal to the metering pump 5, and stop the metering pump 5 to add water to the liquid mixing tank 3; and if the magnetic particle content of the magnetorheological polishing liquid is less than the set value, The computer 2 will always monitor the magnetic particle content in the magnetorheological fluid until it is higher than the set value. The magnetic particle content value generally cannot be set arbitrarily. It is the same as the nature of the magnetorheological polishing fluid itself. , rheology, etc., which are usually set near its initial measured value. Figure 6 shows the flow rate and magnetic particle content control curve of the magnetorheological polishing fluid obtained by using the device and method.

The helical coil 10 can measure the magnetic particle content of the magnetorheological polishing liquid in the circulation. According to the experimental determination, this measurement method is not affected by the flow rate, flow and pressure of the magnetorheological polishing liquid in the circulation, and has a high accuracy, and the hardware implementation is simple. Process experiments show that there is the following relationship between the content of magnetic particles in the magnetorheological polishing fluid and the inductance of the pipeline with the helical coil:

γ=(a*L) ^b +c

Among them, the content of magnetic particles in the γ-magnetorheological polishing fluid

L-liquid inductance value

a, b, c-system constants, related to the properties of the magnetorheological polishing fluid, generally b=1.

Non-polishing circulation mode of magnetorheological polishing fluid:

The non-polishing circulation mode of the magnetorheological polishing fluid mainly includes a liquid mixing tank 3 , a power pump 4 , a switching control valve 12 , a helical coil 10 , an electromagnetic flowmeter 9 and a non-polishing circulation pipeline 18 . The non-polishing cycle mode is mainly to meet the characteristics of long processing cycle, many convergence times, and intermittent repetitions, so that the magnetorheological fluid in the non-polishing state maintains the same stable performance as the magnetorheological fluid in the polishing state, thereby reducing the non-polishing state. The auxiliary time between polishing and polishing improves efficiency, and it does not require special personnel to be on duty, and the design is more humanized. In the non-polishing circulation mode of the magnetorheological polishing fluid, the magnetorheological polishing fluid is pumped out from the liquid mixing tank 3 through the power pump 4, and passes through the pipeline wound with the helical coil 10, the electromagnetic flowmeter 9, the switching control valve 12 and the The non-polishing circulation line 18 returns directly to the liquid mixing tank 3 . Its control method is the same as that of the polishing cycle mode. It also first stabilizes the temperature and flow of the magnetorheological polishing fluid, and then keeps the performance of the magnetorheological polishing fluid stable by monitoring the magnetic particle content of the liquid in real time. Generally speaking, the non-polishing cycle mode is equivalent to the dormant mode. It provides the polishing fluid for magnetorheological polishing, but simply keeps the performance of the liquid unchanged. It is often transferred from the polishing cycle mode to the non-polishing cycle mode, so the set The temperature, flow rate and magnetic particle content do not need to be changed, only the computer 2 controls the switching control valve 12 to close the polishing circulation pipeline 17 and open the non-polishing circulation pipeline 18 at the same time. If you want to return to the polishing cycle state from the non-polishing cycle state, you don’t need to change the set value of temperature, flow rate and magnetic particle content, you only need to control the switching control valve 12 to close the non-polishing cycle line 18 and open the polishing cycle line 17 at the same time , so that the optical processing can be carried out by using the magnetorheological polishing fluid with stable performance, which is simple, convenient, stable and reliable.

Claims (8)

1, stablizes the Magnetorheologicai polishing liquid EGR of polishing fluid performance during a kind of length, it is characterized in that: it comprises liquid blending tank (3), kinetic pump (4), electromagnetic flowmeter (9), nozzle (15), retracting device (11), recovery pump (8), cooler (13), water tank (6) and the computer (2) that links to each other by pipeline, described kinetic pump (4) links to each other with liquid blending tank (3), liquid blending tank (3) links to each other with water tank (6) by measuring pump (5), and cooler (13) links to each other with liquid blending tank (3) by cooling line (16); Form the polishing fluid closed circuit by liquid blending tank (3), electromagnetic flowmeter (9), nozzle (15), retracting device (11) and recovery pump (8) that polishing circulation line (17) links to each other successively, form non-polishing closed circuit by liquid blending tank (3), electromagnetic flowmeter (9) that non-polishing circulation line (18) links to each other successively, the polishing fluid closed circuit is in parallel with non-polishing closed circuit and be provided with switching control valve (12) at both places in parallel, is arranged with spiral winding (10) outside one section pipeline between liquid blending tank (3) and the switching control valve (12); Electromagnetic flowmeter (9) links to each other with the input of spiral winding (10) with computer (2), and the control output end of computer (2) links to each other with switching control valve (12), cooler (13), kinetic pump (4) and measuring pump (5) respectively.

2, stablize the Magnetorheologicai polishing liquid EGR of polishing fluid performance during according to claim 1 length, it is characterized in that: described liquid blending tank (3) comprises liquid blending tank tank body (32) and cooling water tank (36), be provided with internal partition in the liquid blending tank tank body (32), form cooling water tank (36) between internal partition and liquid blending tank tank body (32) outer wall, offer the refluxing opening (30) that links to each other with retracting device (11) on the liquid blending tank tank body (32), offer the cooling water inlet (34) and the coolant outlet (38) that link to each other with cooling line (16) on the cooling water tank (36).

3, stablize the Magnetorheologicai polishing liquid EGR of polishing fluid performance during according to claim 2 length, it is characterized in that: the drive motors (28) of described kinetic pump (4) is installed on the liquid blending tank tank body (32), the kinetic pump pump shaft (29) that links to each other with drive motors (28) is positioned at liquid blending tank tank body (32), is equiped with one or more stirring vane (33) on the described kinetic pump pump shaft (29).

Stablize the Magnetorheologicai polishing liquid EGR of polishing fluid performance during 4, according to claim 1 or 2 or 3 described length, it is characterized in that: described retracting device (11) comprises retracting device seat (26), permanent magnetic strip (23) and retracting device absorption tube (25), the inside of retracting device seat (26) is hollow form and forms between the retracting device liquid storage (24), retracting device absorption tube (25) is installed in (24) between the retracting device liquid storage, retracting device absorption tube (25) links to each other with recovery pump (8), and described permanent magnetic strip (23) is the place, outer ring that the shape that goes in ring is arranged in retracting device seat (26).

Stablize the Magnetorheologicai polishing liquid EGR of polishing fluid performance during 5, according to claim 1 or 2 or 3 described length, it is characterized in that: described nozzle (15) comprises pipe (20) and magnetic defense shell (21) in the nozzle, and pipe (20) is installed in the magnetic defense shell (21) and with polishing circulation line (17) and is connected in the nozzle.

6, stablize the Magnetorheologicai polishing liquid EGR of polishing fluid performance during according to claim 4 length, it is characterized in that: described nozzle (15) comprises pipe (20) and magnetic defense shell (21) in the nozzle, and pipe (20) is installed in the magnetic defense shell (21) and with polishing circulation line (17) and is connected in the nozzle.

Stablize the Magnetorheologicai polishing liquid EGR of polishing fluid performance during 7, according to claim 1 or 2 or 3 described length, it is characterized in that: described computer (2) links to each other with kinetic pump (4) by frequency converter (14).

8, stablize the Magnetorheologicai polishing liquid EGR of polishing fluid performance during according to claim 6 length, it is characterized in that: described computer (2) links to each other with kinetic pump (4) by frequency converter (14).

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