A magnetorheological polishing fluid-controlled grinding and polishing composite processing device and method

Abstract

This invention discloses a magnetorheological fluid-controlled grinding and polishing composite processing device and method, comprising a machine tool, a jet module, a power supply module, and a grinding wheel. The grinding wheel is mounted on the spindle of the machine tool via a processing tool holder. The grinding wheel includes a grinding wheel body and a magnetic supply module. The bottom and outer circumferential surfaces of the grinding wheel body are provided with abrasive surfaces. The grinding wheel body has an inner cavity. The magnetic supply module is installed in the inner cavity of the grinding wheel body to generate a magnetic field on the surface of the grinding wheel body. This invention incorporates a wireless power supply coil and a magnetic field generator into the grinding wheel body used for grinding. The wireless power supply coil is wirelessly powered, and the electrical energy is transmitted to the magnetic field generator. The magnetic field generated by the magnetic field generator allows the magnetorheological polishing fluid to adhere to the surface of the grinding wheel body. By controlling the magnetic field strength on the grinding wheel body, the viscosity of the magnetorheological polishing fluid is changed, thereby achieving controllable shear force and hydrodynamic pressure of the magnetorheological polishing fluid.

Description

Technical Field

[0001] This invention belongs to the field of precision machining technology, specifically relating to a grinding and polishing composite processing device and method controlled by magnetorheological polishing fluid. Background Technology

[0002] In recent years, with the development of advanced grinding processes and the improvement of advanced grinding tool manufacturing technology, the grinding quality of difficult-to-machine materials such as nickel-based superalloys has been improved. Currently, the grinding processes for high-toughness, difficult-to-machine materials commonly employ the following methods: ordinary reciprocating grinding, belt grinding, slow-feed deep-cut grinding, high-speed grinding, and high-efficiency deep-cut grinding. Through these processes, workpieces can achieve better surface finishes and higher dimensional and shape accuracy. However, existing grinding processes involve three stages: rough grinding, semi-finish grinding, and finish grinding, each using different grinding wheels. The workpiece and grinding wheel undergo multiple clamping and positioning operations, which leads to reduced processing efficiency and may also result in decreased dimensional and shape accuracy of the workpiece, ultimately reducing the yield rate.

[0003] Magnetorheological polishing is a technique that utilizes the rheological properties of magnetorheological polishing slurry in a magnetic field to polish workpieces. In a gradient magnetic field, the magnetorheological polishing slurry undergoes rheological phenomena, forming viscoplastic Bingham flexible protrusions. When these flexible protrusions contact the surface of the workpiece and move relative to it, a large shear force is generated on the workpiece surface. Under the action of abrasive particles in the magnetorheological polishing slurry, material removal is achieved. Specifically, the working principle is as follows: the workpiece is brought into contact with the magnetic polishing slurry. Under the influence of an external magnetic field, the magnetic polishing slurry coalesces to form a magnetic brush. When the workpiece and the magnetic brush move relative to each other, they rub against each other, thus polishing the workpiece.

[0004] Therefore, controlling the magnetic polishing slurry to precisely polish localized areas of the workpiece surface during processing is a key technical challenge in existing technologies. In existing technologies, when using an external magnetic field to control the magnetic polishing slurry for polishing, it is difficult to precisely polish localized areas on the interior or exterior surfaces of the workpiece. Summary of the Invention

[0005] The purpose of this invention is to provide a grinding and polishing composite processing device and method controlled by magnetorheological polishing fluid.

[0006] In a first aspect, the present invention provides a composite grinding and polishing processing device controlled by magnetorheological polishing fluid, comprising a machine tool, a jetting module, a power supply module, and a grinding wheel; the grinding wheel is mounted on the spindle of the machine tool via a processing tool holder; the grinding wheel comprises a grinding wheel body and a magnetizing module; the bottom surface and the outer circumferential surface of the grinding wheel body are both provided with a grinding surface; the grinding wheel body has an inner cavity; the magnetizing module is installed in the inner cavity of the grinding wheel body;

[0007] The magnetic supply module includes a first magnetic field generator, a second magnetic field generator, and a wireless power supply coil; the wireless power supply coil is fixed at the center of the inner cavity of the grinding wheel body; multiple first magnetic field generators are installed around the wireless power supply coil, all facing the outer circumferential surface of the grinding wheel; the second magnetic field generator is located at the bottom of the inner cavity of the grinding wheel body; magnetic shielding sheets are provided between the wireless power supply coil and the first and second magnetic field generators.

[0008] The power supply module is installed on the machine tool and supplies power to the first magnetic field generator and the second magnetic field generator through a wireless power supply coil; the jetting module is installed on the machine tool and is used to spray magnetorheological polishing fluid onto the workpiece.

[0009] Preferably, a support is fixed at the center of the inner cavity of the grinding wheel body; a wireless power supply coil is wrapped around the support.

[0010] Preferably, the first magnetic field generator is cuboid and fixed inside the grinding wheel body with screws; the second magnetic field generator is cylindrical and fixed inside the grinding wheel body with screws.

[0011] Preferably, the distance between the first magnetic field generator and the abrasive surface of the outer circumference of the grinding wheel body is 9mm to 10mm; the distance between the second magnetic field generator and the abrasive surface of the bottom surface of the grinding wheel body is 9mm to 10mm.

[0012] Preferably, the jetting assembly includes a liquid storage tank, a liquid outlet pump, a return pump, and a nozzle; the liquid storage tank is fixed on the machine tool; the outlet of the liquid storage tank is connected to the nozzle through the liquid outlet pump; the nozzle is used to spray magnetorheological polishing liquid from the liquid storage tank to the contact position between the grinding wheel body and the workpiece; a liquid storage tank is provided on the worktable of the machine tool; the liquid storage tank and the liquid storage tank are connected through the return pump.

[0013] Preferably, the grinding wheel also includes a cover; the grinding wheel body is closed at the bottom and open at the top; the cover is fixed to the top of the grinding wheel body by hexagonal bolts.

[0014] Thirdly, the present invention provides a grinding and polishing composite processing method. It uses a grinding and polishing composite processing apparatus controlled by a magnetorheological polishing fluid as described in the first aspect; the grinding and polishing composite processing method includes the following steps:

[0015] Step 1: Clamp the workpiece to be processed onto the worktable of the machine tool;

[0016] Step 2: Adjust the distance between the abrasive surface of the grinding wheel body and the surface of the workpiece to the preset distance;

[0017] Step 3: The power supply module wirelessly supplies power to the wireless power supply coil in the magnetization module; the wireless power supply coil supplies power to the first magnetic field generator and the second magnetic field generator, generating a magnetic field that causes the magnetorheological polishing fluid to adhere to the two abrasive surfaces of the grinding wheel body.

[0018] Step 4: The spindle drives the grinding wheel body to rotate and perform grinding along the surface of the workpiece. According to the polishing requirements, the magnetic fields generated by the first magnetic field generator and the second magnetic field generator, as well as the distance between the grinding wheel body and the workpiece, are changed, thereby changing the shearing effect and interstitial fluid dynamic pressure of the magnetorheological polishing fluid.

[0019] Step 5: The grinding wheel body (1) moves along the workpiece to polish the surface material of the workpiece.

[0020] Preferably, during the polishing process, the magnetic field strength of the abrasive surface of the grinding wheel body is greater than 1000 Gs.

[0021] The beneficial effects of this invention are:

[0022] 1. This invention incorporates a wireless power supply coil and a magnetic field generator into the grinding wheel body used for grinding. The wireless power supply coil is wirelessly powered, and the electrical energy is transmitted to the magnetic field generator. The magnetic field generator generates a magnetic field, allowing the magnetorheological polishing fluid to adhere to the surface of the grinding wheel body. By controlling the magnetic field strength on the grinding wheel body, the viscosity of the magnetorheological polishing fluid is altered, thus achieving controllable shear force and hydrodynamic pressure of the magnetorheological polishing fluid.

[0023] 2. This invention features a frosted surface on the grinding wheel body, enabling it to grind the workpiece. Simultaneously, a magnetic field is generated by a magnetic field generator, causing magnetorheological polishing fluid to adhere to the surface of the grinding wheel body. The workpiece surface is then polished using the magnetorheological polishing fluid; this achieves a combined grinding and polishing process, improving processing efficiency.

[0024] 3. This invention employs an electrically controlled magnetic pole method to change the magnetic field lines generated by the grinding wheel body in real time according to requirements, thereby transforming the static magnetic field into a dynamically controllable magnetic field. During or after processing, the abrasive surface of the grinding wheel body comes into contact with a high-viscosity magnetorheological polishing slurry. Utilizing the speed difference between the high-viscosity magnetorheological polishing slurry and the high-speed rotating abrasive surface, the abrasive grains of the grinding wheel are automatically renewed, sharpened, and reshaped, reducing the time required for surface reshaping and improving processing efficiency. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0026] Figure 2 This is a schematic diagram of the structure of the grinding wheel body with a processing tool holder installed in this invention;

[0027] Figure 3 This is a schematic diagram of the magnetization module in this invention;

[0028] Figure 4 This is a schematic diagram showing the relative positions of the wireless power supply coil and the first magnetic field generator in this invention;

[0029] Figure 5 This is a schematic diagram showing the arrangement of the second magnetic field generator on the grinding wheel body in this invention.

[0030] The components include: 1. Grinding wheel body; 2. Magnetizing module; 2-1. First magnetic field generator; 2-2. Second magnetic field generator; 2-3. Wireless power supply coil; 2-4. Control circuit board; 2-5. Support component; 3. Jet module; 3-1. Liquid discharge pump; 3-2. Liquid storage tank; 4. Machine tool; 5. Machining tool holder; 6. Cover; 7. Spindle box. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings.

[0032] like Figure 1 As shown, a magnetorheological polishing fluid-controlled grinding and polishing composite processing device includes a machine tool 4, a grinding wheel, a jetting module 3, a displacement drive module, and a power supply module. The grinding wheel includes a grinding wheel body 1 and a magnetizing module 2. The bottom surface and outer circumferential surface of the grinding wheel body 1 are both provided with abrasive surfaces. The grinding wheel body 1 has an inner cavity. The magnetizing module 2 is installed in the inner cavity of the grinding wheel body 1 and is used to control the magnetorheological polishing fluid inside the machine tool 4. The power supply module is installed on the machine tool 4 and is used to wirelessly power the magnetizing module 2. The grinding wheel is mounted on the spindle of the machine tool 4 via a machining shank 5. Specifically, one end of the machining shank 5 passes through the inner cavity of the support member 2-5 and is fixed to the grinding wheel body 1 by a fastening nut. The machine tool 4 can drive the spindle to rotate along its own axis and move with three degrees of freedom.

[0033] like Figure 2 , 3As shown in Figure 4, the magnetizing module 2 includes a first magnetic field generator 2-1, a second magnetic field generator 2-2, a wireless power supply coil 2-3, a control circuit board 2-4, a support member 2-5, and a mounting plate. The support member 2-5 is cylindrical. The support member 2-5 is fixed to the grinding wheel body 1 by hexagonal set screws. The wireless power supply coil 2-3 surrounds the circumferential surface of the support member 2-5. The mounting plate is fixed to the support member 2-5. The first magnetic field generator 2-1 is cuboid. Multiple first magnetic field generators 2-1 are evenly distributed circumferentially along the axis of the support member 2-5 and fixed to the top surface of the mounting plate by screws. Figure 5 As shown, the second magnetic field generator 2-2 is cylindrical. Multiple second magnetic field generators 2-2 are evenly arranged within the control area of ​​the grinding wheel body 1 and fixed to the bottom surface of the mounting plate with screws. The distance between the outer end face of the first magnetic field generator 2-1 and the frosted surface of the outer circumference of the grinding wheel body 1 is 9mm to 10mm; the distance between the bottom end of the second magnetic field generator 2-2 and the frosted surface of the bottom surface of the grinding wheel body 1 is 9mm to 10mm. The control circuit board 2-4 is fixed to the top surface of the inner cavity of the grinding wheel body 1. A rectifier circuit is provided on the control circuit board 2-4. The first magnetic field generator 2-1, the second magnetic field generator 2-2, and the wireless power supply coil are all connected to the control circuit board 2-4 via wires. During operation, the power supply module wirelessly transmits electrical energy to the wireless power supply coil. The wireless power supply coil transmits electrical energy to the control circuit board 2-4 via wires. The electrical energy is rectified on the control circuit board 2-4 and then transmitted to the corresponding first magnetic field generator 2-1 and second magnetic field generator 2-2. The end face magnetic field strength of the first magnetic field generator 2-1 and the second magnetic field generator 2-2 is greater than 1000 Gs.

[0034] Magnetic shielding sheets are installed between the first magnetic field generator 2-1, the second magnetic field generator 2-2, and the wireless power supply coil 2-3. The installation of these magnetic shielding sheets reduces the influence of external magnetic fields on the magnetorheological polishing fluid during the control of the magnetic fields generated by the first and second magnetic field generators 2-1 and 2-2.

[0035] The spray module 3 includes an outlet pump 3-1, a storage tank 3-2, a return pump, and a nozzle. The storage tank 3-2 is fixed on the machine tool 4. The outlet of the storage tank 3-2 is connected to the nozzle via the outlet pump 3-1. The nozzle is used to spray the magnetorheological polishing fluid in the storage tank 3-2 onto the grinding wheel body 1 being processed. The worktable of the machine tool 4 is equipped with a liquid storage tank; the liquid storage tank is connected to the storage tank 3-2 via the return pump. The return pump transports the magnetorheological polishing fluid in the machine tool 4 to the storage tank 3-2, thus forming a closed loop and achieving the effect of recycling.

[0036] The polishing slurry is an incompressible fluid, formed by uniformly mixing abrasive particles and water in a specific volume ratio. Depending on processing requirements, abrasive particles of the desired size (micrometer, submicrometer, nanometer) and concentration (2%–15%), carbonyl iron powder of the desired size (micrometer, submicrometer) and concentration (2%–20%), dispersant (3%–15%), rust inhibitor (1%–6%), and stabilizer (2%–10%) are added to deionized water. After ultrasonic vibration for 5–30 minutes, thorough stirring is completed to obtain the desired magnetorheological fluid. Both the mixed magnetorheological fluid and polishing slurry are added to storage tank 3-2.

[0037] During processing, the magnetic field strength generated by the first magnetic field generator 2-1 and the second magnetic field generator 2-2, as well as the distance between the grinding wheel body 1 and the workpiece, are changed according to the required polishing degree of the workpiece surface. This alters the shear force and hydrodynamic pressure generated by the magnetorheological polishing fluid adhering to the abrasive surface of the grinding wheel body 1.

[0038] The material removal rate is altered by changing the viscosity of the magnetorheological polishing slurry through varying the magnetic field strength, which in turn changes the dynamic pressure in the polishing zone. This is illustrated by the Reynolds equation, as follows:

[0039]

[0040] In the formula: η represents the dynamic viscosity of the fluid. h represents the thickness of the fluid film, p represents the fluid pressure within the wedge gap, U1 and U2 represent the velocities of the grinding surfaces on the bottom and outer circumference of the grinding wheel body in the x-direction, V1 and V2 represent the velocities of the two surfaces in the y-direction, and W1 and W2 represent the velocities of the two surfaces in the z-direction. In hydrodynamic polishing, the magnetorheological polishing fluid is an incompressible fluid. Therefore, the fluid density ρ can be considered constant, and the variable density effect produced by linear hydrodynamic polishing can be ignored. The above formula can be rewritten as:

[0041]

[0042] During the polishing process with magnetorheological polishing slurry, the movement is relatively stable. If the influence of mechanical vibration during operation is ignored, there is no relative movement between the polishing roller and the bottom surface in the z-direction, and the resulting squeezing effect can be neglected. The above equation can be rewritten as:

[0043]

[0044] As can be seen from the above formula, the magnitude of the fluid dynamic pressure generated by the hydrodynamic lubrication principle is related to the relative speed between the two surfaces, the gap between the two surfaces, the fluid dynamic viscosity, and the coordinate position.

[0045] The Preston equation is the most widely accepted mathematical model for describing the material removal rate during polishing; that is, the material removal rate during the polishing process can be expressed as:

[0046] MMR = KPV

[0047] In the formula, MMR represents the average material removal rate, k is the Preston coefficient, P is the polishing pressure, and V is the relative polishing speed. The Preston coefficient k is related to the workpiece material properties, polishing tool type, polishing temperature, and polishing fluid type; under specific processing conditions, k is a constant. The formula shows that the material removal rate during polishing has a positive linear relationship with both polishing pressure and relative polishing speed.

[0048] When the magnetorheological polishing slurry is subjected to different magnetic field strengths, the viscosity of the magnetorheological polishing slurry also changes. According to the Reynolds equation, when the liquid viscosity changes, the dynamic pressure in the polishing area also changes. According to the Preston equation, when the dynamic pressure changes, the material removal rate on the workpiece surface also changes.

[0049] This invention provides a non-essential technical feature: it also includes a cover 6. The grinding wheel body 1 is closed at the bottom and open at the top, facilitating the installation of parts inside the grinding wheel body 1. The cover 6 is fixed to the top of the grinding wheel body 1 with hexagonal bolts. The cover 6 prevents debris from entering the inner cavity of the grinding wheel body 1 during processing, thus avoiding any impact on the processing.

[0050] The grinding and polishing method of this magnetorheological polishing fluid-controlled grinding and polishing composite processing device has the following specific processing steps:

[0051] Step 1: Based on the structure of the machine tool 4, select the installation location of the power supply module. Then install the debugged grinding wheel body 1 onto the spindle.

[0052] Step 2: The workpiece to be processed is clamped onto the worktable of the machine tool 4 using vacuum adsorption or clamping. Adjust the position of the grinding wheel body 1 so that the distance between the abrasive surface of the grinding wheel body 1 and the surface of the workpiece is 0.5mm to 5mm.

[0053] Step 3: Drive the grinding wheel body 1 to rotate at a speed of 50rpm to 8000rpm and perform grinding along the surface of the workpiece.

[0054] Step 4: The power supply module wirelessly supplies power to the wireless power supply coil 2-3 in the magnetization module 2. The wireless power supply coil transmits electrical energy to the control circuit board 2-4 through wires. The electrical energy is rectified on the control circuit board 2-4 and then transmitted to the corresponding first magnetic field generator 2-1 and second magnetic field generator 2-2. The first magnetic field generator 2-1 and the second magnetic field generator 2-2 generate magnetic fields, causing the magnetorheological polishing fluid to adhere to the two abrasive surfaces of the grinding wheel body 1.

[0055] Step 5: By controlling the magnetic field strength generated on the grinding wheel body 1 and changing the distance between the abrasive surface of the grinding wheel body 1 and the workpiece, the shear force and hydrodynamic pressure of the magnetorheological polishing fluid are controllable. The surface material of the workpiece is polished under the controllable shearing action and interstitial hydrodynamic pressure of the magnetorheological polishing fluid, obtaining a processed surface with the required polishing degree.

Claims

1. A method for magnetorheological finishing and polishing compound machining controlled by a magnetorheological polishing fluid, characterized in that: The grinding and polishing composite machining device comprises a machining machine tool (4), a jet flow module (3), a power supply module and a grinding wheel; the grinding wheel is installed on the main shaft of the machining machine tool (4) through a machining tool holder (5); the grinding wheel comprises a grinding wheel body (1) and a magnetic field supply module (2); the bottom surface and the outer circumferential surface of the grinding wheel body (1) are provided with grinding surfaces; the grinding wheel body (1) is provided with an inner cavity; the magnetic field supply module (2) is installed in the inner cavity of the grinding wheel body (1); the magnetic field supply module (2) comprises a first magnetic field generator (2-1), a second magnetic field generator (2-2) and a wireless power supply coil (2-3); the wireless power supply coil (2-3) is fixed at the center position of the inner cavity of the grinding wheel body (1); a plurality of first magnetic field generators (2-1) are installed around the wireless power supply coil (2-3) and are all directed to the outer circumferential surface of the grinding wheel; the second magnetic field generator (2-2) is arranged at the bottom of the inner cavity of the grinding wheel body (1); the wireless power supply coil (2-3) is provided with a magnetic separation sheet between the first magnetic field generator (2-1) and the second magnetic field generator (2-2); the first magnetic field generator (2-1) is a cuboid and is fixed in the grinding wheel body (1) by screws; the second magnetic field generator (2-2) is a cylinder and is fixed in the grinding wheel body (1) by screws; the distance between the first magnetic field generator (2-1) and the grinding surface of the outer circumferential surface of the grinding wheel body (1) is 9mm-10mm; the distance between the second magnetic field generator (2-2) and the grinding surface of the bottom surface of the grinding wheel body (1) is 9mm-10mm; the magnetic field supply module (2) further comprises a control circuit board (2-4); the control circuit board (2-4) is fixed on the top surface of the inner cavity of the grinding wheel body (1); the control circuit board (2-4) is provided with a rectifier circuit; the power supply module performs wireless transmission of electric energy to the wireless power supply coil; the electric energy of the wireless power supply coil is transmitted to the first magnetic field generator (2-1) and the second magnetic field generator (2-2) after being rectified on the control circuit board (2-4); the jet flow module (3) is installed on the machining machine tool (4) and is used for spraying the magnetorheological polishing liquid to the workpiece; the grinding and polishing composite machining method comprises: step one, installing the grinding wheel body (1) on the main shaft; step two, clamping the workpiece to be machined on the workbench; step three, driving the grinding wheel body (1) to rotate at a speed of 50rpm-8000rpm and grinding along the surface of the workpiece; step four, performing wireless power supply to the wireless power supply coil (2-3) in the magnetic field supply module (2); the first magnetic field generator (2-1) and the second magnetic field generator (2-2) generate a magnetic field, so that the magnetorheological polishing liquid is adhered to the two grinding surfaces of the grinding wheel body (1); by controlling the magnetic field intensity and changing the distance between the grinding surface of the grinding wheel body (1) and the workpiece to be machined, the surface material of the workpiece to be machined is subjected to polishing machining under the controllable shearing action of the magnetorheological polishing liquid and the gap fluid dynamic pressure.

2. The method of claim 1, wherein: The support (2-5) is fixed at the center of the inner cavity of the grinding wheel body (1); and the wireless power supply coil (2-3) is arranged around the support (2-5).

3. The method of claim 1, wherein: The jet flow module comprises a liquid storage tank (3-2), a liquid outlet pump (3-1), a backflow pump and a nozzle; the liquid storage tank (3-2) is fixed on the machining tool (4); the outlet of the liquid storage tank (3-2) is connected to the nozzle through the liquid outlet pump (3-1); the nozzle is used for spraying the magnetorheological polishing liquid from the liquid storage tank (3-2) to the contact position of the grinding wheel body (1) and the workpiece; a liquid storage groove is arranged on the workbench of the machining tool (4); and the liquid storage groove is connected to the liquid storage tank (3-2) through the backflow pump.

4. The method of claim 1, wherein: The abrasive grinding wheel further comprises a cover (6); the grinding wheel body (1) is in a closed bottom and open top shape; and the cover (6) is fixed on the top of the grinding wheel body (1) through a hexagonal bolt.

5. The method of claim 1, wherein: The machining tool (4) can drive the main shaft to rotate around its own axis and move in three degrees of freedom.

6. The method of claim 1, wherein: The second magnetic field generator (2-2) is shared by multiple; multiple second magnetic field generators (2-2) are uniformly arranged at the bottom of the inner cavity of the grinding wheel body (1).

Images