CN110253699A - A method for simulating and optimizing electrolyte machining of small-diameter bamboo holes - Google Patents

Abstract

The invention relates to a method for simulating and optimizing electrolytic solution for processing small-diameter bamboo holes. The method comprises the following steps: (1) making a processing tool cathode and an anode block to be processed; (2) establishing electric field and flow field models for simulation optimization Determine the optimal processing parameters, the optimal processing parameters include processing voltage, electrolyte inlet and outlet speed and the optimal value of electrolyte inlet and outlet pressure; (3) according to the optimal processing parameters determined in step (2), using the processing The cathode of the tool is subjected to electrolytic processing on the anode block to be processed, and small-diameter bamboo holes are formed on the anode block to be processed. Compared with the prior art, the invention has higher processing precision, can process micro-aperture structures, and the surface performance of the processed workpiece will not be affected by cutting force.

Description

A method for simulating and optimizing electrolyte machining of small-diameter bamboo holes

technical field

The invention relates to a method for processing slub holes, in particular to a method for simulating and optimizing electrolyte solution for processing small-diameter slub holes.

Background technique

Electrolytic machining is a manufacturing technology that uses the principle of metal cathode and anode gain and loss electrons to remove materials. It has no tool loss, has nothing to do with the hardness of the material, has high productivity, good surface quality, and can process complex 3D shapes. The slub hole is the application of electrolytic machining to the micro-machining of the inner wall. The slub hole is essentially a ribbed channel, and the inner wall structure is like a bamboo node, so it is called the slub hole. And this internal structure optimizes the cooling structure. By increasing the size of the inner cooling holes, the heat transfer coefficient is effectively improved, thereby achieving the effect of enhanced cooling. More and more domestic and foreign scholars are interested in the research of micro-holes, not only because of the high efficiency of electrolytic machining, but also because of its wide range of applications, deep development capabilities and good prospects. , There are still more links to be improved in terms of processing efficiency.

Contents of the invention

The object of the present invention is to provide a method for simulating and optimizing the electrolytic solution for machining small-diameter bamboo joint holes in order to overcome the above-mentioned defects in the prior art.

The purpose of the present invention can be achieved through the following technical solutions:

A method for simulating and optimizing electrolyte processing small-diameter bamboo holes, the method comprising the following steps:

(1) making the processing tool cathode and the anode block to be processed;

(2) establish electric field, flow field model and carry out simulation optimization to determine optimal processing parameter, described optimal processing parameter comprises the optimal value of processing voltage, electrolyte inlet and outlet speed and electrolyte inlet and outlet pressure;

(3) According to the optimal processing parameters determined in step (2), the cathode of the processing tool is used to electrolytically process the anode block to be processed, and small-diameter bamboo holes are formed on the anode block to be processed.

The cathode of the processing tool is a capillary, and the outer surface of the capillary is provided with a plurality of insulating tapes at intervals along the length direction, and the insulating tape is wrapped around the outer surface of the capillary.

The anode block to be processed is a processed block provided with small holes, and the slub holes are formed in the small holes.

The capillary has an outer diameter of 3 mm and an inner diameter of 1 mm.

In step (2), the optimal value of the machining voltage is determined by the following method: use Auto Cad to establish the electric field model and import it into ANSYS software, set the machining voltage, run the ANSYS software simulation to obtain the electric field contour, measure the bamboo joint hole rib depth in the electric field contour, and adjust Machining voltage until the measured value of rib depth is consistent with the ideal machining value, and the machining voltage at this time is determined as the optimal value of machining voltage.

In step (2), the optimal value of the electrolyte import and export speed is determined as follows:

(1a) Determine the basic range of flow velocity [a, b], where a is the lower limit of flow velocity and b is the upper limit of flow velocity;

(1b) FLUENT software establishes a flow field model, selects a set flow velocity within the basic range of flow velocity [a, b] for simulation, and obtains the corresponding velocity cloud map;

(1c) Analyze the velocity cloud map, and select the corresponding flow velocity when there is no dead water area in the velocity cloud map as the optimal value of the inlet and outlet velocity of the electrolyte.

The base range of the flow rate stated shall satisfy:

Among them, v ₀ is the flow velocity, v is the kinematic viscosity coefficient, and D _h is the hydraulic diameter.

In step (2), the optimal value of the electrolyte inlet and outlet pressure is determined as follows:

(2a) Determine the pressure base range [c, d], where c is the lower limit of the flow rate and d is the upper limit of the flow rate;

(2b) FLUENT software establishes a flow field model, selects a set flow rate within the pressure base range [c, d] for simulation, and obtains the corresponding pressure cloud map;

(2c) Analyze the pressure cloud diagram, and select the corresponding pressure when there is no overload in the pressure cloud diagram as the optimal value of the inlet and outlet speed of the electrolyte.

The stated pressure base range shall meet:

Where, p ₀ is the pressure, p ₁ is the gauge pressure, α ₁ =1, L is the length of the pores, D is the diameter of the pores, ρ is the density of the electrolyte solution, u ₂ is the flow rate, and Re is the Reynolds number.

Compared with the prior art, the present invention has the following advantages: the present invention optimizes the electrolytic machining experiment by establishing electric field and flow field model analysis, and is easy to find out the optimal parameter combination, so that the machining precision is high, and micro-aperture structures, machining Workpiece surface properties are not affected by cutting forces.

Description of drawings

Fig. 1 is the structural representation of the cathode of the processing tool of the present invention;

Fig. 2 is a flow chart of determining the optimal value of machining voltage in the present invention;

Fig. 3 is the structural representation of processing rib depth of the present invention;

Fig. 4 is the process block diagram of determining the optimal value of the inlet and outlet speed of the electrolyte and the optimal value of the inlet and outlet pressure of the electrolyte in the present invention;

Fig. 5 is a schematic diagram of the processing of small-diameter slub holes of the present invention.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. Note that the description of the following embodiments is merely an illustration in nature, and the present invention is not intended to limit the applicable objects or uses thereof, and the present invention is not limited to the following embodiments.

Example

A method for simulating and optimizing electrolyte processing small-diameter bamboo holes, the method comprising the following steps:

(1) making the processing tool cathode and the anode block to be processed;

(2) Establish electric field and flow field models for simulation optimization to determine the optimal processing parameters. The optimal processing parameters include the optimal values of processing voltage, electrolyte inlet and outlet speed, and electrolyte inlet and outlet pressure;

(3) According to the optimal processing parameters determined in step (2), the cathode of the processing tool is used to electrolytically process the anode block to be processed, and small-diameter bamboo holes are formed on the anode block to be processed.

As shown in Figure 1, the cathode of the processing tool is a capillary with an outer diameter of 3 mm and an inner diameter of 1 mm. One end of the capillary is the inlet of the electrolyte, and the outer surface of the capillary is provided with a plurality of insulating tapes 2 at intervals along the length direction, and the insulating tapes 2 are wrapped on the outer surface of the capillary. In order to prevent the occurrence of short circuit during processing and keep the processing tool electrode with a good service life, a support ring can be installed at the end of the formed electrode, and several grooves are opened on the side, so that it is more convenient for the solution to flow from the gap between the cathode and the anode. Pass.

The anode block to be processed is a processing block with small holes, and bamboo holes are formed in the small holes. In this embodiment, the anode is a block with 16 groups of small holes with different processing gaps, because the processing accuracy is relatively high. Therefore, the milling machine is used for processing. During the drilling process, in order to avoid the breakage of the drill bit, the pressure should not be too large when the drilling is fed. In addition, if the drill bit is not sharp, do not use it forcefully, replace it immediately, otherwise the drill bit is most likely to break. Lock the movement of the worktable perpendicular to the center of the drill bit, and only keep the movement of the worktable in the same direction as the center of the drill bit to avoid the gap and vibration of the workbench in other directions. When drilling, first select a reference point, and ensure the verticality and levelness of the workpiece on the drilling table, so that after processing, as long as the reference point is aligned with the CNC engraving and milling machine, the tool can be referred to before Relative coordinates on the machine tool for fast processing positioning. In this embodiment, 4x4 small holes arranged in a matrix are drilled on the block, the apertures are respectively 4.1, 4.2, 4.3, and 4.4 mm, and the depth is 25 mm.

As shown in Figure 2, the optimal value of the machining voltage in step (2) is determined by the following method: use Auto Cad to establish the electric field model and import it into the ANSYS software, set the machining voltage, run the ANSYS software simulation to obtain the electric field nephogram, and measure the bamboo in the electric field nephogram. Node hole rib depth, adjust the machining voltage until the rib depth measurement value is consistent with the ideal machining value, and determine the machining voltage at this time as the optimal value of machining voltage.

Specifically, in this embodiment, the cloud image of the electric field obtained by simulation with a certain processing voltage, it can be seen from the cloud image that the rib depth (h in Figure 3 is the rib depth) is constantly changing with time, and the electrolytic reaction at the beginning of processing Violent, as the processing time gets longer and longer, the distance between the cathode and anode becomes larger and larger. According to the principle of electrolytic machining, when the distance between the cathode and anode reaches a certain size, the current on the surface of the anode becomes smaller, so the electrolysis Slower and slower, at this time the workpiece cannot be electrolytically machined, and finally the rib depth tends to a certain value. Now the rib height is 0.2mm as a standard. If the rib height is low after measurement, increase the processing voltage, and the electric field around the tool electrode will become larger after pressurization, and the metal farther away from the tool will also be affected by the electric field, and will be gradually corroded, and the rib height will increase; otherwise, if When the rib height is high, reduce the voltage.

As shown in Figure 4, the optimal value of the electrolyte import and export speed in step (2) is determined by the following method:

(1a) Determine the basic range of flow velocity [a, b], where a is the lower limit of flow velocity and b is the upper limit of flow velocity;

(1b) FLUENT software establishes a flow field model, selects a set flow velocity within the basic range of flow velocity [a, b] for simulation, and obtains the corresponding velocity cloud map;

(1c) Analyze the velocity cloud map, and select the corresponding flow velocity when there is no dead water area in the velocity cloud map as the optimal value of the inlet and outlet velocity of the electrolyte.

The basic range of flow rate needs to meet:

Among them, v ₀ is the flow velocity, v is the kinematic viscosity coefficient, and D _h is the hydraulic diameter.

In this embodiment, the value of D _h is the value of the inner hole gap, therefore, it satisfies:

At the same time, a higher flow rate is beneficial to suppress the temperature rise in the processing gap, thereby improving the stability of the processing process. Set the selection range of flow velocity as 10-20m/s, now select different set values of 10, 15, and 20m/s, input them into the setting boundary condition module of FLUENT software, start the 2D solver operation and solve, and generate the velocity cloud map . Analyzing the generated velocity cloud image, when a dead water zone is formed in the workpiece, it indicates that the flow velocity should not be too fast, and the flow velocity setting value can be appropriately lowered. After setting several groups of experiments with different flow rates, the degree of corrosion of the inner wall of the processed bamboo hole by the electrolyte solution can be compared, and then the flow rate can also be adjusted to obtain the optimal flow rate parameters.

In step (2), the optimal value of the electrolyte inlet and outlet pressure is determined as follows:

(2a) Determine the pressure base range [c, d], where c is the lower limit of the flow rate and d is the upper limit of the flow rate;

(2b) FLUENT software establishes a flow field model, selects a set flow rate within the pressure base range [c, d] for simulation, and obtains the corresponding pressure cloud map;

(2c) Analyze the pressure cloud diagram, and select the corresponding pressure when there is no overload in the pressure cloud diagram as the optimal value of the inlet and outlet speed of the electrolyte.

The pressure base range needs to meet:

Where, p ₀ is the pressure, p ₁ is the gauge pressure, α ₁ =1, L is the length of the pores, D is the diameter of the pores, ρ is the density of the electrolyte solution, u ₂ is the flow rate, and Re is the Reynolds number.

In this example:

That is, the solution pressure at the inlet should be greater than 0.28Mpa. But it should not be too large to prevent overload and the situation that the water in the workpiece cannot flow out. Set the selection range of flushing pressure as 0.3～0.5Mpa, and now choose different setting values of 0.3, 0.35, 0.4, 0.45, 0.5MPa for experiments, (4) input the data into the setting condition module of FLUENT software, start 2D The solver operation solves to generate a pressure contour. (5) Set several groups of experiments and analyze the pressure cloud diagram. It can be seen that where the bamboo joint hole protrudes, the pressure value is relatively high. Compare several groups of bamboo joint holes processed by different flushing pressure values, and then combine the pressure cloud diagram. As a result of the pressure distribution, the optimal pressure parameters can be obtained.

Finally, the anode block is processed, and the specific processing schematic diagram is shown in Figure 5. In the figure, A is the cathode of the processing tool, B is the anode block to be processed, and C is the electrolyte, which is sodium nitrate solution. The way of flushing liquid, the power supply adopts DC power supply.

The above-mentioned embodiments are merely examples, and do not limit the scope of the present invention. These embodiments can also be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the scope of the technical idea of the present invention.

Claims (9)

1. a kind of method in simulation optimization electrolyte machining small diameter ring hole, which is characterized in that this method comprises the following steps:

(1) machining tool cathode and anode object block to be processed are made；

(2) electric field is established, flow field model carries out simulation optimization and determines that optimal machined parameters, the optimal machined parameters include adding The optimal value of work voltage, electrolyte inlet and outlet speed and electrolyte inlet and outlet pressure；

(3) the optimal machined parameters determined according to step (2), are electrolysed anode object block to be processed using machining tool cathode Processing forms small-bore ring hole on anode object block to be processed.

2. a kind of method in simulation optimization electrolyte machining small diameter ring hole according to claim 1, which is characterized in that The machining tool cathode is capillary, and the extracapillary surface is spaced the multiple insulating tapes of setting, institute along its length The insulating tape stated is wrapped in extracapillary surface.

3. a kind of method in simulation optimization electrolyte machining small diameter ring hole according to claim 2, which is characterized in that The anode object block to be processed is to set foraminate machining object block, and the ring hole forming is in the aperture.

4. a kind of method in simulation optimization electrolyte machining small diameter ring hole according to claim 2, which is characterized in that The capillary outer diameter is 3mm, internal diameter 1mm.

5. a kind of method in simulation optimization electrolyte machining small diameter ring hole according to claim 1, which is characterized in that Machining voltage optimal value is determined as follows in step (2): establishing electric field model using Auto Cad and to import ANSYS soft Part, given machining voltage, operation ANSYS software emulation obtain electric field cloud atlas, measure rib depth in ring hole in electric field cloud atlas, adjust and add Work voltage is consistent with ideal value processing up to rib depth measured value, and machining voltage at this time is determined as machining voltage optimal value.

6. a kind of method in simulation optimization electrolyte machining small diameter ring hole according to claim 1, which is characterized in that Electrolyte inlet and outlet speed optimal value is determined as follows in step (2):

(1a) determines flow velocity basic scope [a, b], and wherein a is lower flow rate limit, and b is maximum flow rate；

(1b) FLUENT software establishes flow field model, and setting flow velocity is chosen in flow velocity basic scope [a, b] and is emulated, is obtained Corresponding speed cloud atlas；

(1c) analyzes speed cloud atlas, and corresponding flow velocity imports and exports speed most as electrolyte when in access speed cloud atlas without slough The figure of merit.

7. a kind of method in simulation optimization electrolyte machining small diameter ring hole according to claim 6, which is characterized in that The flow velocity basic scope needs to meet:

Wherein, v₀For flow velocity, v is coefficientof kinematic viscosity, D_hFor water conservancy diameter.

8. a kind of method in simulation optimization electrolyte machining small diameter ring hole according to claim 1, which is characterized in that Electrolyte inlet and outlet pressure optimal value is determined as follows in step (2):

(2a) determines pressure-based range [c, d], and wherein c is lower flow rate limit, and d is maximum flow rate；

(2b) FLUENT software establishes flow field model, and setting flow velocity is chosen in pressure-based range [c, d] and is emulated, is obtained Corresponding pressure cloud atlas；

(2c) analyzes pressure cloud atlas, and it is optimal as electrolyte inlet and outlet speed to choose corresponding pressure when No-mistake Principle in pressure cloud atlas Value.

9. a kind of method in simulation optimization electrolyte machining small diameter ring hole according to claim 8, which is characterized in that The pressure-based range needs to meet:

Wherein, p₀For pressure, p₁For gauge pressure, α₁=1, L are opening length, and D is hole diameter, and ρ is electrolyte solution density, u₂For Flow velocity, Re are Reynolds number.