CN102009388A - Miniature metal-based grinding wheel on-line electrolytic electric spark dressing device and method - Google Patents

Abstract

An in-situ electrolytic spark dressing device and a dressing method for a metal-based micro-grinding wheel in the field of mechanical manufacturing technology, the device includes: a mechanical movement system, a power supply system, a working fluid system and a control system. The present invention utilizes the characteristic that the processing electrode is lossy, and uses a micro-grinding wheel as the electrode, so that the metal bond on the grinding wheel electrode is affected by the electrolytic spark effect and is eroded away to achieve the purpose of dressing the grinding wheel, with high dressing efficiency and no damage to the abrasive grains. Small damage, low cost, very suitable for off-line or in-situ dressing of miniature metal-based grinding wheels.

Description

In-situ electrolytic spark dressing device and dressing method for metal-based micro-grinding wheel

technical field

The invention relates to a device and a method in the technical field of mechanical manufacturing, in particular to an in-situ electrolysis EDM dressing device and a dressing method for a metal-based micro-grinding wheel based on the electrolysis EDM effect.

Background technique

Micro-grinding has a wide range of applications in micro-electro-mechanical systems, biomedicine, aerospace and other fields. The diameter of micro-grinding wheels used in micro-grinding is usually hundreds of microns to several millimeters, and they are mainly divided into electroplated grinding wheels and sintered grinding wheels. The electroplating grinding wheel is a layer of abrasive grains electroplated on the surface of the substrate, and the price is low. However, since there is only one layer of abrasive grains, it is easy to wear during processing, and the life of the grinding wheel is short. The sintered grinding wheel is sintered by a bond (usually metal) and a superhard abrasive material. After dressing, it can be used repeatedly and has a long service life. However, how to dress this grinding wheel has become a difficult problem. Common mechanical dressing methods, such as using dish-shaped grinding wheels for grinding, rolling, etc., will cause large grinding force and grinding temperature, and damage the abrasive grains. In addition, the mechanical dressing method is inefficient, and the wear of the dresser is very large. For micro-grinding wheels and micro-processing, mechanical dressing can also cause plastic deformation of the grinding wheel and reduce the precision of micro-grinding. Non-traditional wheel dressing methods, such as EDM dressing, in-line electrolytic dressing, and laser dressing can overcome the inherent shortcomings of mechanical dressing methods, but come with high costs, which are not suitable for auxiliary processes such as micro wheel dressing .

As early as the mid-nineteenth century, some scholars have discovered and studied the electrolytic spark effect. That is, during the electrolysis process, the two poles of the power supply are immersed in the electrolyte. If one of the electrodes is very small and the power supply voltage is increased above 25V, a large number of bubbles generated on this electrode can evolve into a dense gas layer to insulate the electrode. , so that the discharge between the electrode and the electrolyte breaks down the gas layer due to the voltage difference, which is the so-called electrolytic spark effect. Electrolytic EDM was first proposed by Japanese scholars in 1968, and it has been used in the microprocessing of glass, quartz, ceramics and other materials. In EDM, both the workpiece material and the electrode are affected by galvanic erosion and chemical dissolution by the spark. Electrode materials are generally high temperature resistant and corrosion resistant conductive materials such as stainless steel. If other metals (such as copper, etc.) are used, the electrode loss rate is very high. However, if the micro-grinding wheel is used as an electrode, this electrode loss can be used to remove the metal bond material of the grinding wheel to achieve the purpose of dressing the grinding wheel.

Contents of the invention

Aiming at the above-mentioned deficiencies in the prior art, the present invention provides an in-situ electrolytic EDM dressing device and a dressing method for a metal-based micro grinding wheel. On the basis of the existing electrolytic EDM technology for non-conductive materials, the processing electrode The characteristic of consumption is to use the micro grinding wheel as the electrode, so that the metal bond on the grinding wheel electrode is affected by the electrolytic spark effect and is eroded to achieve the purpose of dressing the grinding wheel. The method of the present invention has high dressing efficiency and little damage to the abrasive grains. Inexpensive and ideal for off-line or in-situ dressing of miniature metal-based grinding wheels.

The present invention is achieved through the following technical solutions:

The invention relates to an in-situ electrolytic spark trimming device for a metal-based micro-grinding wheel, comprising: a mechanical motion system, a power supply system, a working fluid system and a control system, wherein: the mechanical motion system is connected with the control system and accepts the motion control of the control system Command information and feedback actual position information, the power supply system is connected with the mechanical movement system, so that the micro grinding wheel becomes one pole of the power supply, and the other pole of the power supply system is connected with the working fluid system to form an electrochemical reaction circuit. Provide energy, the working fluid system is used to provide ions and dielectrics for the reaction, the power supply system is connected to the control system to receive the power parameter control instruction information of the control system, and the working fluid system is connected to the control system to transmit the status information of the working fluid to the control system.

The mechanical motion system includes: a high-speed rotating main shaft and three sets of linear slides, wherein: the high-speed rotating main shaft includes: a rotating mechanism, a motor, a frequency converter and a cooling and lubricating device, the rotating mechanism is mechanically connected to the motor and driven by the motor, and the motor and Inverter connection, the inverter controls the speed and torque of the motor, etc., the cooling and lubricating device is connected to the rotating mechanism through a pipeline, and sprays air and oil mist into the rotating mechanism to realize cooling and lubrication of the rotating mechanism; the linear slide table includes a linear motion mechanism, Stepper motor and stepper motor driver, wherein: the linear motion mechanism is mechanically connected with the stepper motor and driven by the stepper motor to realize linear movement, the stepper motor is connected with the stepper motor driver, and the stepper motor driver controls the movement of the stepper motor Position, speed and acceleration, etc.; three sets of linear slides are installed orthogonally to realize the three-dimensional parallel movement of the high-speed rotating spindle, and the high-speed rotating spindle is installed vertically downward on the linear slide in the vertical direction.

The rotating mechanism is composed of a rotor, a stator and a bearing.

The cooling lubricating device is composed of an air pump, lubricating oil and filter.

The linear slide table is a linear movement mechanism composed of a guide rail, a slider, a lead screw and a linear bearing.

The power supply system includes: a DC power supply and an auxiliary electrode, wherein: one pole of the DC power supply is connected to the mechanical movement system, so that the micro grinding wheel becomes one pole of the power supply, and the other pole is connected to the auxiliary electrode; the auxiliary electrode is placed in the working fluid system. in the electrolyte.

The auxiliary electrode is made of anti-corrosion conductive material.

The working fluid system includes: a working fluid tank and an electrolyte, wherein: the working fluid tank is placed horizontally within the reachable range of the mechanical movement system, the electrolyte is contained in the working fluid tank, and the working fluid tank is made of corrosion-resistant materials production.

The electrolyte is a strong alkali solution, such as sodium hydroxide or potassium hydroxide mixed with water in a certain proportion.

The control system includes: a programmable controller, an operation panel, a control circuit, a grinding wheel state monitor and a working fluid state monitor, wherein: the programmable controller executes a pre-written program to realize real-time control of each system, which can The programmable controller is connected with the operation panel, and transmits the operation and display information; the programmable controller is connected with the control circuit to realize the closing and disconnection of the circuit, and the circuit protection; the programmable controller is connected with the grinding wheel status monitor, and transmits the grinding wheel Status information, the grinding wheel status monitor has multiple installation methods according to the monitored signal objects; the working fluid status monitor is installed in the working fluid tank of the working fluid system, and the programmable controller is connected with the working fluid status monitor and transmitted Working fluid status information.

The present invention relates to the in-situ trimming method of above-mentioned device, comprises the following steps:

The first step is to install the micro-grinding wheel on the high-speed spindle of the mechanical motion system and perform micro-grinding;

The second step, when the grinding wheel needs to be trimmed, stop the grinding process, the linear slide table of the mechanical motion system moves the micro grinding wheel to the top of the working fluid tank of the working fluid system and immerses the auxiliary electrode in the electrolyte, and connects with the positive electrode of the DC power supply Connect the negative pole of the DC power supply to the high-speed spindle of the mechanical motion system, so that the micro grinding wheel becomes the negative pole of the power supply, and keep the electrolyte liquid level stable during the period;

Step 3: The mechanical motion system moves the micro-grinding wheel downwards, decelerates and moves down slowly when approaching the liquid level of the electrolyte, and stops moving when it touches the liquid level;

The fourth step is to close the dressing power supply, the phenomenon of electrolytic electric spark occurs on the processing surface of the grinding wheel, and the grinding wheel bond material and attached workpiece material are gradually removed and the abrasive grains are exposed.

Compared with the prior art, the present invention applies the electrolytic spark effect to the dressing of the micro-grinding wheel, and has the following remarkable advantages: (1) The dressing efficiency is high. During the trimming, the thermal erosion of the spark and the electrochemical reaction between the chemical solution and the metal bond are used to remove the metal bond material, which has a high material removal rate. (2) The trimming quality is high. The shape accuracy of the trimming process is guaranteed by the horizontal liquid level. The trimming process is the selective removal of material. Generally, the binder material of the grinding wheel is metal (copper alloy, etc.), which is easily removed by the electrolytic spark effect. The abrasive material is generally diamond or cubic boron carbide, which is neither conductive nor easily affected by ambient temperature and chemical corrosion. Therefore, while the metal bond is removed, the abrasive material remains intact. The in-situ dressing of the grinding wheel effectively avoids the positioning error caused by the secondary clamping. (3) Flexible control. The dressing process can be adjusted by changing the immersion depth of the grinding wheel, voltage, electrolyte concentration, dressing time, etc. In particular, the trimming effect can be changed by changing the voltage, which is very convenient. (4) Low cost, economical and practical. This method is simple and practical. Compared with other non-traditional trimming methods (such as EDM trimming), it uses ordinary low-voltage power supply without special spark pulse power supply, and does not need closed-loop control of distance between electrodes. More importantly, since the method uses the electrolyte as the trimming electrode, the cost of trimming electrode loss and the man-hours for trimming the electrode are greatly saved.

Description of drawings

Fig. 1 is a schematic diagram of the structure of the present invention.

Figure 2 is a schematic diagram of the high-speed rotating spindle.

Figure 3 is a schematic diagram of a linear slide.

Figure 4 is a schematic diagram of the power system and working fluid system.

Figure 5 is a schematic diagram of the control system.

Detailed ways

The embodiments of the present invention are described in detail below. This embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operating procedures are provided, but the protection scope of the present invention is not limited to the following implementation example.

As shown in Figure 1, this embodiment includes: a mechanical motion system 1, a power supply system 2, a working fluid system 3 and a control system 4, wherein: the mechanical motion system 1 is connected with the control system 4, and accepts motion control instructions from the control system 4 The power system 2 is connected with the mechanical motion system 1, so that the micro grinding wheel becomes one pole of the power supply, and the other pole of the power system 2 is connected with the working fluid system 3 to form an electrochemical reaction loop. The power system 2 It is used to provide energy for the reaction. The working fluid system is used to provide ions and dielectrics for the reaction. The power supply system 2 is connected to the control system 4 to receive the power parameter control instruction information of the control system 4. The working fluid system 3 is connected to the control system 4. The status information of the working fluid is transmitted to the control system 4 .

The mechanical motion system 1 includes: a high-speed rotating spindle 5 and three sets of linear slides 6, wherein:

As shown in Figure 2, described high-speed rotating main shaft 5 comprises: rotating mechanism 7, motor 8, frequency converter 9 and cooling lubricating device 10, wherein: rotating mechanism 7 is mechanically connected with motor 8 and is driven by motor 8, and motor 8 and The frequency converter 9 is connected, and the frequency converter 9 controls the speed and torque of the motor 8. The cooling and lubricating device 10 is connected to the rotating mechanism 7 through a pipeline, and sprays air and oil mist into the rotating mechanism 7 to realize cooling and lubrication of the rotating mechanism 7;

As shown in Figure 3, described linear slide table 6 comprises: linear motion mechanism 11, stepper motor 12 and stepper motor driver 13, wherein: linear motion mechanism 11 is mechanically connected with stepper motor 12 and is driven by stepper motor 12 The drive realizes linear movement, the stepper motor 12 is connected with the stepper motor driver 13, and the stepper motor driver 13 controls the position, speed and acceleration of the stepper motor 12; three sets of linear slides 6 are installed orthogonally to realize high-speed rotation of the main shaft 5 three-dimensional parallel movement, the high-speed rotating main shaft 5 is installed vertically downward on the linear slide table 6 in the vertical direction.

The rotating mechanism 7 is composed of a rotor 14 , a stator 15 and a bearing 16 .

Described cooling lubricating device 10 is made up of air pump 17, lubricating oil 18, filter 19.

The linear slide table 6 is a linear movement mechanism composed of a guide rail 20 , a slide block 21 , a screw 22 and a linear bearing 23 .

As shown in Figure 4, described power supply system 2 comprises: DC power supply 24 and auxiliary electrode 25, wherein: one pole of DC power supply 24 is connected to mechanical motion system 1, makes micro-grinding wheel become one pole of power supply, and the other pole is connected to Auxiliary electrode 25 ; the auxiliary electrode 25 is placed in the electrolyte of the working fluid system 3 .

The auxiliary electrode is made of anti-corrosion conductive material.

The working fluid system 3 includes: a working fluid tank 26 and an electrolyte 27, wherein the working fluid tank is placed horizontally within the reachable range of the mechanical motion system 1, the electrolyte is contained in the working fluid tank, and the working fluid tank Made of corrosion resistant material.

The electrolyte is a strong alkali solution, such as sodium hydroxide or potassium hydroxide mixed with water in a certain proportion.

As shown in Figure 5, the control system 4 includes: a programmable controller 28, an operation panel 29, a control circuit 30, a grinding wheel status monitor 31 and a working fluid status monitor 32, wherein: the programmable controller 28 executes the The written program realizes the real-time control of each system, the programmable controller 28 is connected with the operation panel 29, and transmits operation and display information; the programmable controller 28 is connected with the control circuit 30 to realize the closing and disconnection of the circuit, and the circuit Protection; the programmable controller 28 is connected with the grinding wheel status monitor 31, and transmits the status information of the grinding wheel. The grinding wheel status monitor 31 has multiple installation methods according to the different signal objects to be monitored; the working fluid status monitor 32 is installed in the working fluid system In the working fluid tank 26 of 3, the programmable controller 28 is connected with the working fluid status monitor 32, and transmits the status information of the working fluid.

The in-situ trimming method of the device comprises the following steps:

The first step is to install the micro-grinding wheel on the high-speed spindle of the mechanical motion system 1 and perform micro-grinding. During processing, sensors are used to monitor the state of the grinding wheel, and the collected signals are processed by an algorithm to evaluate the state of the grinding wheel. When the grinding wheel condition evaluation is low, the micro-grinding process is interrupted and the operator is prompted that the grinding wheel needs to be dressed. Otherwise continue processing.

In the second step, when the grinding wheel needs to be trimmed, the grinding process is stopped, and the linear sliding table 6 of the mechanical motion system 1 moves the miniature grinding wheel to the top of the working fluid tank of the working fluid system 3 . The auxiliary electrode is immersed in the electrolyte and connected to the positive pole of the DC power supply. The negative pole of the DC power supply is connected to the high-speed spindle of the mechanical motion system 1, so that the micro grinding wheel becomes the negative pole of the power supply. The electrolyte level should be kept as stable as possible.

In the third step, the mechanical movement system 1 moves the micro-grinding wheel downwards, slows down when approaching the liquid level of the electrolyte, and changes it to a slow downward movement. When it touches the liquid surface, the movement stops, and at this time, the processing surface of the grinding wheel is just in contact with the electrolyte liquid surface. The depth of the grinding wheel submerged in the liquid surface can be adjusted according to the actual situation. Set trimming parameters on the operation panel of the control system 4, such as loading voltage and trimming time, etc., and trimming is ready.

The fourth step is to close the dressing power supply, and the electrolysis electric spark phenomenon occurs on the processing surface of the grinding wheel. In this way, the grinding wheel bond material and attached workpiece material are gradually removed, exposing the abrasive grains, and achieving the purpose of grinding wheel dressing.

The fifth step, after finishing, cut off the power supply, the linear slide table 6 of the mechanical motion system 1 drives the grinding wheel to move upward to a safe position, and disconnect the negative pole of the DC power supply from the high-speed spindle of the mechanical motion system 1. The micro grinding wheel returns to the original grinding processing area and continues to complete the grinding processing task. After multiple repairs, the state of the electrolyte drops, and the control system 4 detects it and prompts that the electrolyte needs to be replaced.

Take the off-line dressing of copper bond polycrystalline diamond micro-grinding wheel by electrolytic spark as an example. The micro-grinding wheel used in the machining was a 0.75 mm diameter copper bonded polycrystalline diamond wheel with 220 grit size. The power supply 24 is a low-voltage DC power supply (0-32V, 300W), one pole of which is connected to the grinding wheel through the main shaft, and the other pole is connected to the auxiliary electrode 25, and the auxiliary electrode material is graphite. The grinding workpiece is placed on the workbench, and the micro-grinding process can be continued after finishing. After the micro-grinding wheel is worn, the grinding wheel is dressed by electrolytic sparking method, and the surface morphology and grinding force before and after dressing are compared. The surface morphology was observed with an optical microscope, and the roughness was measured with a surface profiler; the grinding force was measured with a piezoelectric dynamic meter.

The parameters that embodiment grinding process uses are as follows:

Choose the trimming parameters as follows:

Before dressing: The grinding surface of the grinding wheel is severely worn, and the abrasive grains are covered by bonding agent and workpiece material. The surface of the workpiece is uneven, accompanied by grinding burn marks, and the surface roughness is Ra 0.77. The axial grinding force during processing is about 1.6N.

After Dressing: Bond material is removed, abrasive grains are exposed, and the abrasive grains are intact. The surface of the workpiece is smooth without burn marks, and the surface roughness is Ra 0.39. The axial grinding force is reduced to 0.8N during processing, and the processing quality is significantly improved.

Through comparative experiments, it can be seen that the new micro grinding wheel dressing method based on the electrolytic spark effect and the corresponding processing system can effectively improve the state of the grinding wheel, improve the processing quality and the service life of the grinding wheel.

Claims (6)

1. A metal-based miniature grinding wheel in-situ electrolytic spark dressing device, characterized in that it includes: a mechanical motion system, a power supply system, a working fluid system and a control system, wherein: the mechanical motion system is connected with the control system, and accepts the control system The motion control command information and feedback the actual position information, the power system is connected with the mechanical motion system, so that the micro grinding wheel becomes one pole of the power supply, and the other pole of the power system is connected with the working fluid system to form an electrochemical reaction loop. To provide energy for the reaction, the working fluid system is used to provide ions and dielectrics for the reaction, the power supply system is connected to the control system to receive the power parameter control command information of the control system, and the working fluid system is connected to the control system to transmit the status information of the working fluid to the Control System. 2. The in-situ electrolytic spark dressing device for metal-based micro-grinding wheels according to claim 1, wherein the mechanical motion system includes: a high-speed rotating spindle and three sets of linear slides, wherein: the high-speed rotating spindle includes: Rotating mechanism, motor, frequency converter and cooling and lubricating device. The rotating mechanism is mechanically connected to the motor and driven by the motor. The motor is connected to the frequency converter, and the frequency converter controls the speed and torque of the motor. Spray air and oil mist into the rotating mechanism to realize cooling and lubrication of the rotating mechanism; the linear slide table includes a linear motion mechanism, a stepping motor and a stepping motor driver, wherein: the linear motion mechanism is mechanically connected with the stepping motor and is controlled by the stepping motor The drive realizes linear movement, the stepper motor is connected with the stepper motor driver, and the stepper motor driver controls the position, speed and acceleration of the stepper motor; three sets of linear slides are installed orthogonally to realize the three-dimensional parallel movement of the high-speed rotating spindle , the high-speed rotating spindle is installed vertically downward on the linear slide table in the vertical direction. 3. The in-situ electrolytic spark dressing device for metal-based micro-grinding wheel according to claim 1, characterized in that, the power supply system includes: a DC power supply and an auxiliary electrode, wherein: one pole of the DC power supply is connected to the mechanical motion system , so that the micro grinding wheel becomes one pole of the power supply, and the other pole is connected to the auxiliary electrode; the auxiliary electrode is placed in the electrolyte of the working fluid system. 4. The in-situ electrolytic spark dressing device for metal-based micro-grinding wheel according to claim 1, characterized in that, the working fluid system includes: working fluid tank and electrolyte, wherein: the working fluid tank is placed horizontally in the mechanical movement Within the reachable range of the system, the electrolyte is contained in the working fluid tank, which is made of corrosion-resistant materials. 5. The in-situ electrolytic spark dressing device for metal-based micro-grinding wheel according to claim 1, wherein said control system comprises: a programmable controller, an operation panel, a control circuit, a grinding wheel status monitor and a working fluid Status monitor, in which: the programmable controller executes pre-written programs to realize real-time control of each system, the programmable controller is connected with the operation panel, and transmits operation and display information; the programmable controller is connected with the control circuit to realize Closing and disconnection of the circuit, circuit protection; the programmable controller is connected with the grinding wheel status monitor and transmits the status information of the grinding wheel. The grinding wheel status monitor has various installation methods according to the monitored signal objects; the working fluid status monitor is installed In the working fluid tank of the working fluid system, the programmable controller is connected with the working fluid status monitor and transmits the status information of the working fluid. 6. An in-situ electrolytic spark trimming method according to the device according to claim 1, characterized in that, comprising the following steps: The first step is to install the micro-grinding wheel on the high-speed spindle of the mechanical motion system and perform micro-grinding; The second step, when the grinding wheel needs to be trimmed, stop the grinding process, the linear slide table of the mechanical motion system moves the micro grinding wheel to the top of the working fluid tank of the working fluid system and immerses the auxiliary electrode in the electrolyte, and connects with the positive electrode of the DC power supply Connect the negative pole of the DC power supply to the high-speed spindle of the mechanical motion system, so that the micro grinding wheel becomes the negative pole of the power supply, and keep the electrolyte liquid level stable during the period; Step 3: The mechanical motion system moves the micro-grinding wheel downwards, decelerates and moves down slowly when approaching the liquid level of the electrolyte, and stops moving when it touches the liquid level; The fourth step is to close the dressing power supply, and the electrolytic spark phenomenon occurs on the processing surface of the grinding wheel, gradually removing the grinding wheel bond material and the attached workpiece material and exposing the abrasive grains.

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