Discharge-electrochemical rough machining method for metal-based composite material

Abstract

The invention belongs to the technical field of combined machining, and discloses a metal matrix composite discharge-electrochemical rough machining method which comprises the following steps: step 1, acquiring a workpiece and a tool electrode, and selecting machining power supply parameters and regulating and controlling resistance values based on the volume fraction of reinforced phase particles of the workpiece; secondly, a machining power source, a regulation resistor and the workpiece are electrically connected in sequence, the negative electrode of the machining power source is electrically connected with the regulation resistor and the tool electrode in sequence, and the positive electrode of the machining power source is electrically connected with the workpiece; thirdly, the electrolyte is started, so that the gap between the tool electrode and the workpiece is filled with the electrolyte, and a machining power source and a regulation and control resistor are started; fourthly, the tool electrode is made to move relative to the workpiece along a preset feeding track; and the step 3 to the step 4 are repeated until the workpiece is machined. According to the technical scheme, for metal-based composite materials with different reinforcement phase volume fractions, efficient machining with the discharging effect and the electrochemical effect being considered is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of composite processing, and in particular relates to a rough processing method for metal-based composite materials combining discharge and electrochemistry. Background Art

[0002] Discharge-electrochemical composite machining is a non-contact machining technology based on electrochemical corrosion and discharge effects. It can be used for machining insulating materials such as titanium alloys, high-temperature alloys or ceramics. The energy source of electrolysis and discharge is electrical energy. Under electrolysis, the workpiece material is dissolved into the electrolyte in the form of ions, so that the workpiece material is removed; under discharge, the workpiece material is removed by the heat between the cathode and cathode.

[0003] At present, the research on discharge-electrochemical composite machining methods is mainly concentrated in two directions. One is the machining process based on discharge, which uses the extremely high energy discharge generated during the machining process to quickly erode a large amount of workpiece material, thereby obtaining a higher material removal rate. The other is the machining process based on electrolysis, which uses the characteristics of high surface quality of electrolytic machining to obtain good surface quality.

[0004] The discharge-electrochemical composite machining method is mainly based on discharge action. During the machining process, the discharge current reaches hundreds of amperes and the discharge duration reaches several milliseconds. This discharge belongs to arc discharge, and its energy is thousands of times that of electric spark discharge. Under the high-intensity discharge action, a large amount of workpiece material is melted, gasified and thrown out, achieving extremely high machining efficiency. However, due to the excessive discharge energy, on the one hand, it will cause serious electric shock, thereby reducing the machining efficiency. On the other hand, the excessive discharge energy will also cause the discharge pits on the workpiece surface to be too large, and the electrolytic action is not enough to remove the surface defects, reducing the machining accuracy and surface quality.

[0005] The discharge-electrochemical composite machining method mainly based on electrolysis has a very strong electrolysis during the machining process. The workpiece is continuously dissolved and removed under high electrolysis current density, so it usually has a higher surface quality and machining accuracy. At this time, the discharge effect is weaker, and the discharge effect plays an auxiliary role in the electrolysis, promoting the breakage of the passivation film in the machining area. However, this type of machining process usually faces the problem of low machining efficiency, which limits the further application of this method.

[0006] For metal matrix composites, there are large differences in the volume fraction of reinforcement phase particles. When processing low volume fraction metal matrix composites, due to the small content of high melting point reinforcement phase particles, high processing efficiency can be obtained when the discharge effect is weak; as the content of high melting point and non-conductive reinforcement phase increases, the discharge effect needs to be enhanced to obtain a high material removal rate. Therefore, for metal matrix composites with different volume fractions, processing techniques with different intensities of discharge and electrolysis are required to obtain better processing performance. However, the existing processing methods are all through the regulation of electrical parameters and non-electrical parameters, and the process window is very narrow, and it is impossible to achieve the separate regulation of discharge and electrolysis. Therefore, there are problems such as poor processability when processing metal matrix composites with different volume fractions.

[0007] Therefore, how to balance the electrolysis and discharge effects is of great significance to the further promotion of discharge-electrochemical composite processing methods and the further application of metal matrix composites. Summary of the invention

[0008] The purpose of the present invention is to provide a rough processing method for metal-based composite materials that emphasizes both discharge and electrochemical processing, so as to solve the problems existing in the above-mentioned prior art.

[0009] To achieve the above object, the present invention provides a rough machining method of a metal matrix composite material by both discharge and electrochemical treatment, comprising:

[0010] Step 1: Obtain a workpiece and a tool electrode, wherein the workpiece is a metal matrix composite material, obtain the volume fraction of the reinforcement phase particles of the workpiece, and select a processing power source and a regulating resistor based on the volume fraction of the reinforcement phase of the workpiece;

[0011] Step 2: electrically connecting the machining power supply, the regulating resistor and the workpiece in sequence, and electrically connecting the machining power supply to the tool electrode;

[0012] Step 3: Filling the gap between the tool electrode and the workpiece with electrolyte to cause an electrochemical reaction and produce a processing product;

[0013] Step 4: moving the tool electrode relative to the workpiece along a preset feed trajectory;

[0014] Repeat steps 3 to 4 until the workpiece is processed.

[0015] Optionally, the processing power source and the regulating resistance are selected based on the volume fraction of the workpiece reinforcement phase, specifically including:

[0016] The voltage of the machining power supply and the resistance value of the regulating resistor are set based on the volume fraction of the reinforcement phase particles of the workpiece.

[0017] Optionally, setting the voltage of the processing power supply and the resistance value of the regulating resistor specifically includes:

[0018] When the volume fraction of the workpiece is low, the voltage of the processing power supply is 100-200V, and the resistance of the regulating resistor is 0.5-1.0Ω;

[0019] When the volume fraction of the workpiece is a medium volume fraction, the voltage of the machining power supply is 40-100V, and the resistance of the regulating resistor is 0.1-0.5Ω;

[0020] When the volume fraction of the workpiece is high, the voltage of the machining power supply is 40-80V, and the resistance of the regulating resistor is 0.05-0.1Ω.

[0021] Optionally, the processing power supply adopts a direct current power supply.

[0022] Optionally, in the process of moving the tool electrode along a preset feed trajectory relative to the workpiece, the process also includes rotating the tool electrode around an axis along a preset rotation direction.

[0023] Optionally, a central hole is provided inside the tool electrode, so that the electrolyte enters into the machining gap between the tool electrode and the workpiece through the central hole of the tool electrode to cause an electrochemical reaction.

[0024] Optionally, the electrolyte is a neutral salt solution.

[0025] Optionally, the processing product includes insoluble processing products and detached silicon carbide particles.

[0026] The technical effects of the present invention are:

[0027] 1. By connecting different regulating resistors in series in the processing circuit, the discharge current in the processing circuit can be controlled, but it will not have a significant impact on the electrochemical dissolution. For low volume fraction metal-based composite materials, increasing the resistance of the regulating resistor can obtain a weaker discharge effect and a stronger electrochemical dissolution effect; reducing the resistance of the regulating resistor can obtain a stronger discharge effect and a weaker electrochemical dissolution effect. For metal-based composite materials with different volume fractions, different processing effects can be achieved by changing the resistance of the regulating resistor and the processing voltage. For metal-based composite materials with different volume fractions, a processing technology that emphasizes both discharge and electrochemical dissolution is achieved.

[0028] 2. Under the action of regulating resistance, there will be no excessively high energy discharge during the discharge-electrochemical composite machining process, which effectively controls the discharge current, reduces the tool electrode loss, increases the service life of the tool electrode, reduces the machining cost, and improves the machining efficiency.

[0029] 3. Under the action of regulating resistance, the discharge current is controlled, and less workpiece material is removed in a single discharge, which improves the localization of processing. At the same time, low-energy discharge also reduces tool electrode loss, so the electrolysis current also increases, achieving efficient processing that emphasizes both discharge and electrochemical effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0032] Figure 1 It is a schematic diagram of the discharge-electrochemical rough machining method of the metal matrix composite material in an embodiment of the present invention;

[0033] Figure 2 This is a comparison diagram of machining current when a 0.1Ω regulating resistor is connected in series and when no regulating resistor is connected in series in a machining loop in an embodiment of the present invention;

[0034] Figure 3 A comparison diagram of material removal rates when a 0.1Ω regulating resistor is connected in series and when no regulating resistor is connected in series in a machining loop in an embodiment of the present invention;

[0035] Figure 4 A comparison diagram of tool electrode loss when a 0.1Ω regulating resistor is connected in series and when no regulating resistor is connected in series in a machining circuit in an embodiment of the present invention;

[0036] Label names: 1. Tool electrode feed direction; 2. Electrolyte; 3. Insoluble product; 4. Processing power supply; 5. Regulating resistor; 6. Workpiece; 7. Debonded silicon carbide particles; 8. Tool electrode; 9. Tool electrode rotation direction. DETAILED DESCRIPTION

[0037] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0038] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0039] Embodiment 1

[0040] like Figure 1 - Figure 4 As shown, in this embodiment, a rough machining method of a metal-based composite material combining discharge and electrochemistry is provided, comprising: obtaining a workpiece 6 and a tool electrode 8, wherein the workpiece 6 is a metal-based composite material, obtaining the volume fraction of the reinforcing phase particles of the workpiece 6, and selecting a machining power source 4 and a regulating resistor 5 based on the volume fraction of the reinforcing phase of the workpiece 6; step two: electrically connecting the machining power source 4, the regulating resistor 5 and the workpiece 6 in sequence, and electrically connecting the machining power source 4 to the tool electrode 8; step three: filling an electrolyte 2 in the gap between the tool electrode 8 and the workpiece 6 to cause an electrochemical reaction and produce a machining product; step four: moving the tool electrode relative to the workpiece 6 along a preset feed trajectory; and repeating steps three to four until the workpiece 6 is machined.

[0041] The method proposed in this embodiment connects a regulating resistor 5 in series between the tool electrode 8 or the workpiece 6 and the machining power supply 4, and limits the current in the machining circuit by regulating the resistor 5, thereby realizing the regulation of the discharge effect in the discharge-electrochemical composite machining. For metal-based composite materials with high volume fractions, a regulating resistor 5 with a smaller resistance is used, so that a stronger discharge effect and a weaker electrochemical dissolution effect are generated in the machining circuit; for metal-based composite materials with low volume fractions, a regulating resistor 5 with a high resistance is used, so that a weaker discharge effect and a stronger electrochemical dissolution effect are generated in the machining circuit. According to the characteristics of the workpiece material, by connecting regulating resistors 5 with different resistances in series in the machining circuit, the discharge current and the electrochemical dissolution current in the machining circuit are regulated, thereby realizing a rough machining method for metal-based composite materials that emphasizes both discharge and electrochemistry.

[0042] This embodiment can achieve rough machining of metal-based composite materials with different volume fractions. The connection relationship includes: the tool electrode 8 is connected to the negative electrode of the machining power supply 4, the workpiece 6 is connected to the positive electrode of the machining power supply 4, and the regulating resistor 5 is located between the tool electrode 8 or the workpiece 6 and the machining power supply 4. A high-conductivity electrolyte 2 is used as the working medium for discharge-electrochemical composite machining, and the electrolyte 2 enters the machining area through the center hole of the tool electrode 8. The tool electrode 8 rotates around its axis and continuously feeds along the feed direction. Discharge occurs between the tool electrode feed direction 1 and the workpiece 6, and electrochemical reactions occur simultaneously or alternately in other areas. A large amount of insoluble machining products and silicon carbide particles 7 that are passively detached due to electrochemical dissolution are generated in the machining area.

[0043] Implementation process: Install the tool electrode 8, align the tool, introduce the electrolyte 2 into the tool electrode 8, and set the voltage of the machining power supply 4 and the resistance of the regulating resistor 5 according to the reinforcing phase content of the workpiece 6. While the machining power supply 4 is running, the tool electrode 8 operates according to the predetermined program.

[0044] Wherein, the workpiece 6 is a metal-based composite material, and the resistance of the regulating resistor 5 ranges from 0.05 to 1Ω.

[0045] The machining power source 4 used in the discharge electrolytic composite machining process is a DC non-pulse power source or a DC pulse power source.

[0046] The electrolyte 2 is a neutral salt solution, and the solute of the neutral salt solution is sodium chloride or sodium nitrate, and the solvent of the neutral salt solution is water or ethylene glycol; the mass fraction of the solute of the neutral salt solution is greater than 5%.

[0047] If the workpiece 6 is a low volume fraction metal matrix composite material, the regulating resistor 5 is set to 0.5-1.0Ω, and the voltage of the processing power supply 4 is set to 100-200V; if the workpiece 6 is a medium volume fraction metal matrix composite material, the regulating resistor 5 is set to 0.1-0.5Ω, and the voltage of the processing power supply 4 is set to 40-100V; if the workpiece 6 is a high volume fraction metal matrix composite material, the regulating resistor 5 is set to 0.05-0.1Ω, and the voltage of the processing power supply 4 is set to 40-80V. The discharge equivalent resistance varies from 0.05 to 0.3Ω, and the equivalent resistance of electrochemical dissolution varies from 0.5 to 1Ω. In the electrochemical dissolution process, the voltage occupied by the regulating resistor 5 is much smaller than the voltage occupied by the equivalent resistance of electrochemical dissolution, that is, the existence of the regulating resistor 5 has little effect on the electrochemical dissolution. In the discharge process, the discharge equivalent resistance is small, so extremely high energy discharge will be generated in the processing process, which will cause serious electrode loss, thereby reducing the processing efficiency, so the discharge current is controlled by connecting the regulating resistor 5 in series. Since low volume fraction metal matrix composites contain only a small amount of reinforcement phase particles, it does not require excessively high energy arc discharge to achieve high processing efficiency. Low volume fraction metal matrix composites contain a large amount of metal matrix, so increasing the processing voltage can enhance the electrochemical dissolution effect and quickly remove the material. As the reinforcement phase content increases, the discharge current must be increased to quickly remove the high melting point reinforcement phase. Correspondingly, as the metal matrix content decreases, the electrolysis current must be reduced to prevent excessive electrochemical action from deteriorating the processing effect. When processing high volume fraction metal matrix composites, a strong discharge action is required to remove the reinforcement phase, and a weaker electrolysis action is required to remove the metal matrix.

[0048] This embodiment can control the discharge current in the processing circuit by connecting different control resistors 5 in series in the processing circuit, but will not have a significant impact on the electrochemical dissolution. For metal-based composite materials with low volume fractions, increasing the resistance of the control resistor 5 can obtain a weaker discharge effect and a stronger electrochemical dissolution effect; reducing the resistance of the control resistor 5 can obtain a stronger discharge effect and a weaker electrochemical dissolution effect. For metal-based composite materials with different volume fractions, by changing the resistance of the control resistor 5 and the processing voltage, a processing technology that emphasizes both discharge and electrochemical dissolution can be achieved.

[0049] In this embodiment, under the action of the regulating resistor 5, excessively high energy discharge will not occur during the discharge-electrochemical composite machining process, the discharge current is effectively controlled, the wear of the tool electrode 8 is reduced, the service life of the tool electrode 8 is increased, the machining cost is reduced, and the machining efficiency is improved.

[0050] In this embodiment, under the action of the regulating resistor 5, the discharge current is controlled, and less material of the workpiece 6 is removed in a single discharge, thereby improving the localization of processing. At the same time, the low-energy discharge also reduces the loss of the tool electrode 8, so the electrolysis current also increases, thereby achieving efficient processing that emphasizes both discharge and electrochemical effects.

[0051] Figure 1 The figure shows a schematic diagram of a rough machining method for metal matrix composite materials with both discharge and electrochemistry. The tool electrode 8 is connected to the negative electrode of the machining power source 4, the workpiece 6 is connected to the positive electrode of the machining power source 4, and the regulating resistor 5 is located between the tool electrode 8 or the workpiece 6 and the machining power source 4. The regulating resistor 5 is used to limit the discharge current during the discharge process, and the existence of the regulating resistor 5 has little effect on the electrochemical dissolution process. The resistance value of the regulating resistor 5 is determined according to the material of the workpiece 6. If the workpiece 6 is a metal matrix composite material with a low volume fraction, the regulating resistor 5 is set to 0.5-1.0Ω, and the voltage of the machining power source 4 is set to 100-200V; if the workpiece 6 is a metal matrix composite material with a medium volume fraction, the regulating resistor 5 is set to 0.1-0.5Ω, and the voltage of the machining power source 4 is set to 40-100V; if the workpiece 6 is a metal matrix composite material with a high volume fraction, the regulating resistor 5 is set to 0.05-0.1Ω, and the voltage of the machining power source 4 is set to 40-80V.

[0052] An electrolyte 2 with high conductivity is used as the working medium of the discharge-electrochemical composite machining, and the electrolyte 2 enters the machining area through the center hole of the tool electrode 8. The tool electrode 8 rotates around its axis and continuously feeds along the feed direction. Discharge occurs between the tool electrode feed direction 1 and the workpiece 6, and electrochemical reactions occur simultaneously or alternately in other areas. A large amount of insoluble machining products and silicon carbide particles 7 that are passively detached due to electrochemical dissolution are generated in the machining area.

[0053] The specific example of this embodiment is: the material of the workpiece 6 used in this embodiment is 45 vol% SiC P / Al, belongs to the medium volume fraction metal matrix composite material, silicon carbide is evenly distributed in the aluminum matrix in the form of particles. The regulating resistor 5 with a resistance of 0.1Ω is connected in series to the processing circuit before the experiment. During the experiment, a cerium tungsten electrode with an outer diameter of 6mm and an inner diameter of the center hole of 3mm is used as the tool electrode 8. A 20wt% NaCl solution is used as the electrolyte 2, the temperature of the electrolyte 2 is 30℃, and the pressure is 0.6MPa. The processing voltage is set to 40V, and the feed rate is 60mm / min. Figure 2 This is a comparison of the processing circuit current without the series control resistor 5 and after the series control resistor 5. Figure 2 It can be seen that after the 0.1Ω regulating resistor 5 is connected in series in the processing circuit, the discharge current in the processing circuit exceeds 1000A and drops to about 220A, and the electrolysis current increases to about 26A. Figure 3 It can be seen that after the 0.1Ω regulating resistor 5 is connected in series in the machining loop, the discharge effect is suppressed, the electrolysis effect is enhanced, and the overall material removal rate remains stable. 3 / min reduced to 262.69mm 3 / min, the material removal rate of electrochemical dissolution is from 60.03mm 3 / min increased to 82.75mm 3 / min. Figure 4 It can be seen that after the 0.1Ω regulating resistor 5 is connected in series in the machining circuit, thanks to the regulation of the discharge current, the relative electrode loss rate is reduced from 2.23% to 1.39%, and the loss volume of the tool electrode 8 is reduced from 3.44mm 3 Reduced to 1.83mm 3 .

[0054] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0055] The above is only a preferred specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A rough processing method for metal matrix composite materials by both discharge and electrochemical treatment, characterized in that: include: Step 1: obtaining a workpiece (6) and a tool electrode (8), wherein the workpiece (6) is a metal matrix composite material, obtaining the volume fraction of the reinforcement phase particles of the workpiece (6), and selecting a processing power source (4) and a regulating resistor (5) based on the volume fraction of the reinforcement phase of the workpiece (6); Step 2: electrically connecting the machining power supply (4), the regulating resistor (5) and the workpiece (6) in sequence, and electrically connecting the machining power supply (4) and the tool electrode (8); Step 3: Filling the gap between the tool electrode (8) and the workpiece (6) with an electrolyte (2) to cause an electrochemical reaction and produce a processing product; Step 4: moving the tool electrode (8) relative to the workpiece (6) along a preset feed trajectory; Repeat steps 3 to 4 until the workpiece (6) is processed.

2. A method for rough machining of metal matrix composite materials by both discharge and electrochemical treatment according to claim 1, characterized in that: Selecting a processing power source (4) and regulating a resistor (5) based on the volume fraction of the reinforcement phase of the workpiece (6) specifically includes: Based on the volume fraction of the reinforcement phase particles of the workpiece (6), the voltage of the processing power supply (4) and the resistance value of the regulating resistor (5) are set.

3. A rough machining method for metal matrix composite materials by both discharge and electrochemical treatment according to claim 2, characterized in that: Setting the voltage of the processing power supply (4) and the resistance value of the regulating resistor (5) specifically includes: When the volume fraction of the workpiece (6) is low, the voltage of the processing power supply (4) is 100-200V, and the resistance of the regulating resistor (5) is 0.5-1.0Ω; When the volume fraction of the workpiece (6) is a medium volume fraction, the voltage of the processing power supply (4) is 40-100V, and the resistance of the regulating resistor (5) is 0.1-0.5Ω; When the volume fraction of the workpiece (6) is a high volume fraction, the voltage of the machining power supply (4) is 40-80V, and the resistance of the regulating resistor (5) is 0.05-0.1Ω.

4. The method for rough machining of metal matrix composite materials by both discharge and electrochemical treatment according to claim 1, characterized in that: The processing power source (4) adopts a direct current power source.

5. The method for rough machining of metal matrix composite materials by both discharge and electrochemical treatment according to claim 1, characterized in that: The process of moving the tool electrode (8) relative to the workpiece (6) along a preset feed trajectory also includes rotating the tool electrode (8) around an axis along a preset rotation direction (9).

6. The method for rough machining of metal matrix composite materials by both discharge and electrochemical treatment according to claim 1, characterized in that: A central hole is provided inside the tool electrode (8), so that the electrolyte (2) enters the machining gap between the tool electrode (8) and the workpiece (6) through the central hole of the tool electrode (8), thereby generating an electrochemical reaction.

7. The method for rough machining of metal matrix composite materials by both discharge and electrochemical treatment according to claim 1, characterized in that: The electrolyte (2) is a neutral salt solution.

8. The method for rough machining of metal matrix composite materials by both discharge and electrochemical treatment according to claim 1, characterized in that: The processed product includes an insoluble processed product (3) and detached silicon carbide particles (7).

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