A part internal passage finishing device and method

Abstract

The application discloses a part inner channel finishing device and method, and relates to the technical field of plasma-assisted electrolytic processing.The device comprises a traction line, a power supply, a power supply line, a first plugging head, a second plugging head and a cathode.The method comprises the following steps:S1, the traction line, the first plugging head, the cathode and the second plugging head are sequentially placed into one end of an inner channel, and the end of the traction line, which is away from the first plugging head, is pulled out from the other end of the inner channel;S2, the positive pole of the power supply is electrically connected with a part;S3, then the power supply is turned on for finishing;S4, after a preset time period in step S3, the first plugging head is pulled by the traction line, so that the first plugging head, the cathode and the second plugging head move along the inner channel by a preset distance;S5, step S4 is repeated;S6, the power supply is turned off, and the traction line, the first plugging head, the cathode and the second plugging head are taken out.The application improves the efficiency and quality of part inner channel finishing.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of plasma-assisted electrolytic machining, in particular to a finishing device and method for internal channel of a part. BACKGROUND

[0002] In the parts formed by additive manufacturing process, many parts have internal channels, and there are many problems of powder adhesion and high surface roughness after printing. How to realize the finishing machining of the internal channel of the above-mentioned target part without damaging the surface and size of the part is a difficult problem that puzzles manufacturing and machining.

[0003] Currently, for the surface roughness problem of the channel with large cross-sectional size, there are methods such as manual polishing, abrasive flow machining, electrochemical polishing, water jet, sand blasting, CNC grinding and polishing, and laser polishing. For the parts with complex curved surface and complex center line structure channel, abrasive flow machining and electrochemical polishing have good machining accessibility, so they are the main finishing technologies currently used.

[0004] However, because abrasive flow machining mainly relies on abrasives to remove the surface material of the channel, it will cause overcut at the far end such as the inlet when finishing the internal surface, and the area with large internal angle change cannot be effectively finished, and how to clean the residues of the abrasives is also a new problem. Further, the processing efficiency of abrasive flow machining is very low, and the processing localization is poor. For the auxiliary support structure that may exist inside, it is impossible to completely remove the auxiliary support structure without affecting the dimensional accuracy of the structure, or in other words, when the auxiliary support is completely removed, the accuracy of other areas is affected due to overcut. Therefore, abrasive flow machining is not suitable for removing the residues of the parts.

[0005] Electrochemical machining does not need the semi-solid abrasives of abrasive flow machining and uses electrolyte with good fluidity for machining, but an electrode is needed for electrolytic machining, and how to adapt the shape of the electrode to the internal channel is a difficult problem. In addition, the existing electrochemical machining method is to use a bendable electrode structure and wrap an insulator outside to adapt the shape of the channel by using a flexible electrode for electrochemical finishing machining. Its highlight is to overcome the limitations of the rigid electrode of traditional electrochemical machining. However, if the insulating tube (or porous insulating medium) is used outside the electrode for finishing machining of the channel, the following problems will be caused:

[0006] (1) It is impossible to realize plasma-assisted machining of the excess material in the internal surface of the channel. Generally, the area of the anode (i.e. the internal surface of the workpiece) is much larger than that of the cathode, which will cause excessive gas formation at the anode, and thus cause the voltage at both ends of the insulating layer to be too high, resulting in gas discharge and forming spark discharge pits to damage the surface of the workpiece, which cannot achieve polishing effect;

[0007] (2) The flushing in electrochemical machining is a very important implementation condition, and if the size of the insulating sleeve is consistent with the size of the channel to be machined, it will cause the problem that the flushing cannot be implemented or the flow rate is too small, which greatly reduces the stability and efficiency of the machining; even if a porous structure is used, the fluid passability will be greatly reduced;

[0008] (3) There is a gap between the sleeves in the channel, which easily causes the direct contact between the electrode and the protruding part of the residue on the channel wall in the curved channel, thereby forming a short circuit and damaging the stability of the machining;

[0009] (4) The periodic interval of the exposed part of the insulating sleeve and the electrode means that the electric field action area is uneven or even continuous during machining, which easily causes the uneven etching amount of the side wall, and the uniformity needs to be controlled by the feed amount (feed speed multiplied by time), and due to the fact that the gap is filled with elastic material, it is very difficult to achieve uniform removal;

[0010] (5) The electrode etching product between the two sections of the insulating sleeve is easy to accumulate, which further increases the difficulty of discharge, and even causes the termination of the reaction;

[0011] (6) The efficiency of simple electrolytic machining is low.

[0012] Since the emergence of metal additive manufacturing technology, the problem of internal excess material and auxiliary support has not been comprehensively solved, which has become a bottleneck problem for the further popularization and application of the technology.

[0013] Therefore, there is an urgent need in the market for a part internal channel finishing device and method to solve the above problems. SUMMARY

[0014] The purpose of the present application is to provide a part internal channel finishing device and method to solve the above problems of the prior art, remove the surface residue in the internal channel of the part manufactured by additive manufacturing, and realize the finishing of the internal surface of the channel.

[0015] To achieve the above purpose, the present application provides the following solutions:

[0016] The application provides a part inner channel finishing device, which comprises a traction line, a power supply, a power supply line, a first sealing head, a second sealing head and a cathode, the first sealing head and the second sealing head are spaced apart and insulated, when the first sealing head is arranged in the inner channel of the part, the edges of the first sealing head are tightly fitted with the inner wall of the inner channel, one end of the traction line is fixedly connected with the end of the first sealing head away from the second sealing head, one end of the power supply line is electrically connected with the negative electrode of the power supply, the other end of the power supply line is fixedly connected with the first sealing head, the power supply line passes through the second sealing head and is fixedly connected with the second sealing head, the cathode is located between the first sealing head and the second sealing head and is electrically connected with the power supply line, a liquid outlet is arranged on the first sealing head, and a liquid flushing outlet is arranged on the second sealing head, and the positive electrode of the power supply is used for being electrically connected with the part.

[0017] A gas outlet is arranged on the second sealing head, or a gap is formed between part of the edges of the second sealing head and the inner wall of the inner channel when the second sealing head is arranged in the inner channel.

[0018] Preferably, the first sealing head and the second sealing head are both made of elastic insulating material.

[0019] Preferably, the axial cross-sectional profile of the cathode is circular, triangular, arc-shaped or polygonal.

[0020] Preferably, the cathode comprises a plurality of electrode pieces which are uniformly distributed in the circumferential direction and any two adjacent electrode pieces are connected with each other.

[0021] Preferably, when the first sealing head and the second sealing head are arranged in the inner channel, the area of the inner wall of the inner channel between the first sealing head and the second sealing head is smaller than the surface area of the cathode.

[0022] Preferably, the device further comprises an insulating liquid flushing baffle, and the liquid flushing baffle is fixedly sleeved on the cathode.

[0023] Preferably, there is a gap between the edge of the liquid flushing baffle and the inner wall of the inner channel, and the area of the liquid flushing baffle is greater than the projection area of the cathode on the liquid flushing baffle.

[0024] Preferably, the liquid flushing outlet is communicated with a working liquid source through a liquid flushing pipe, and the liquid outlet is communicated with a working liquid recovery tank or the working liquid source through a liquid outlet pipe.

[0025] The application further provides a part inner channel finishing method, which is based on the part inner channel finishing device and comprises the following steps.

[0026] S1, sequentially put the traction line, the first plugging head, the cathode and the second plugging head into one end of the inner channel, and make the end of the traction line away from the first plugging head pass out from the other end of the inner channel, and make the first plugging head and the second plugging head have the maximum interval;

[0027] S2, electrically connect the positive pole of the power supply with the part;

[0028] S3, turn on the power supply, and polish the inner wall of the inner channel between the first plugging head and the second plugging head;

[0029] S4, after a preset time period of step S3, pull the first plugging head through the traction line, so that the first plugging head, the cathode and the second plugging head move a preset distance along the inner channel, and the interval between the first plugging head and the second plugging head is equal to the preset distance;

[0030] S5, repeat step S4 until the polishing of all areas in the inner channel of the part is completed;

[0031] S6, turn off the power supply, and take out the traction line, the first plugging head, the cathode and the second plugging head.

[0032] The present application has the following technical effects relative to the prior art:

[0033] The part inner channel polishing device and method of the present application improve the efficiency and quality of the polishing of the inner channel of the part.

[0034] Further, the chamber is formed between the first plugging head and the second plugging head, the gas film is only generated on the surface of the workpiece inner channel in the chamber and the contact area with the working liquid, the amount of the gas film can be effectively controlled, and the phenomenon that the electric spark in the gas is generated due to the excessive voltage at both ends of the insulation layer caused by the excessive gas formed by the anode, and the workpiece surface is damaged by the electric spark is avoided.

[0035] Further, in the present application, the contact area of the cathode with the working liquid is greater than the contact area of the anode with the working liquid, the excessive gas formed by the anode (the excessive gas generated by the anode will form a relatively thick insulation layer, and the breakdown discharge is generated), and the plasma generated by the anode is ensured, and the reaction of the anode is accelerated by the plasma.

[0036] Further, the liquid flushing baffle is used to block the working liquid flushed through the liquid flushing pipe, so as to control the liquid flushing flow field, and the excessive gas in the chamber is taken out of the chamber with the working liquid, and the spark discharge in the gas caused by the excessive gas is avoided.

[0037] Further, a gas film layer is generated on the anode surface during the electrochemical reaction process, and the plasma-assisted electrochemical discharge machining formed by breaking the gas film layer combines the electrolysis and discharge machining processes, and has higher efficiency and is more effective for removing the auxiliary support.

[0038] Further, the first and second plugs in the present application are made of elastic insulating material, and the edge of the first plug is tightly attached to the surface of the inner channel to be finished under the elasticity of the first plug, so as to avoid the gap between the edge of the first plug and the surface of the inner channel to be finished, and avoid the working liquid and the gas generated by the anode from flowing out of the chamber through the edge of the first plug; in addition, since the first and second plugs are made of elastic insulating material, the first and second plugs cannot pass through the inner channel due to the protrusion of the surface of the inner channel. BRIEF DESCRIPTION OF DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description only constitute some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor based on these drawings.

[0040] Figure 1 FIG. 1 is a structural schematic diagram of the part inner channel finishing device according to the first embodiment of the present application;

[0041] Figure 2 FIG. 2 is a structural schematic diagram of the first plug in the part inner channel finishing device according to the first embodiment of the present application;

[0042] Figure 3 FIG. 3 is a structural schematic diagram of the second plug in the part inner channel finishing device according to the first embodiment of the present application;

[0043] Figure 4 FIG. 4 is a structural schematic diagram of the cathode and the liquid flushing baffle in the part inner channel finishing device according to the first embodiment of the present application;

[0044] Figure 5 FIG. 5 is a structural schematic diagram of the cathode and the liquid flushing baffle in the part inner channel finishing device according to the second embodiment of the present application;

[0045] In the drawings, 100 is a part inner channel finishing device, 1 is a part, 2 is a power supply line, 3 is a second plug, 301 is a groove, 4 is a liquid flushing port, 5 is a cathode, 6 is a liquid flushing baffle, 7 is a first plug, 8 is an inner channel, 9 is a traction line, 10 is a liquid outlet, and 11 is a power supply. DETAILED DESCRIPTION

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] The purpose of this invention is to provide a finishing device and method for the inner channel of a part, so as to solve the problems existing in the prior art, remove surface residues in the inner channel of the additively manufactured part, and achieve finishing of the inner surface of the channel.

[0048] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0049] Example 1

[0050] like Figures 1 to 4 As shown, this embodiment provides a part inner channel finishing device 100, including a traction wire 9, a power supply 11, a power line 2, a first sealing head 7, a second sealing head 3, and a cathode 5. The first sealing head 7 and the second sealing head 3 are spaced apart and insulated from each other. When the first sealing head 7 is placed in the inner channel 8 of the part 1, all edges of the first sealing head 7 are tightly fitted with the inner wall of the inner channel 8. One end of the traction wire 9 is fixedly connected to the end of the first sealing head 7 away from the second sealing head 3. One end of the power line 2 is electrically connected to the negative terminal of the power supply 11, and the other end is fixedly connected to the first sealing head 7. The power line 2 passes through the second sealing head 3 and is fixedly connected to the second sealing head 3. The cathode 5 is located between the first sealing head 7 and the second sealing head 3 and is electrically connected to the power line 2.

[0051] The first sealing head 7 is provided with a liquid outlet 10, and the second sealing head 3 is provided with a flushing port 4. In this embodiment, the flushing port 4 is connected to the working fluid source through a flushing pipe, and the liquid outlet 10 is connected to the working fluid recovery tank or the working fluid source through an outlet pipe. A pump body can also be provided on the outlet pipe to provide power for the return of the working fluid. The working fluid in the working fluid source is sent to the chamber formed between the first sealing head 7 and the second sealing head 3 through the flushing pipe and the flushing port 4 for electrochemical reaction in the chamber. The working fluid in the chamber can flow to the working fluid recovery tank or the working fluid source through the liquid outlet 10 and the outlet pipe.

[0052] It should be noted that the positive terminal of the power supply 11 is used to electrically connect with the component 1. After the component 1 is electrically connected to the positive terminal of the power supply 11, the component 1 as a whole acts as the anode, and an electrochemical reaction is formed between the surface of the inner channel 8 of the component 1 and the cathode 5.

[0053] In the optional solution of the embodiment, preferably, the edge of the second plug 3 is circumferentially and uniformly provided with a plurality of axial grooves 301, so that when the second plug 3 is arranged in the inner channel 8, a gap is formed between the edge of the second plug 3 and the inner wall of the inner channel 8, which serves as the gas outlet of the gas generated on the surface of the anode, i.e. the inner channel 8. Of course, in actual application, the grooves 301 in the embodiment can not be arranged on the edge of the second plug 3, and only the gas outlet for the gas generated on the surface of the anode, i.e. the inner channel 8, can be arranged on the second plug 3.

[0054] In the embodiment, the first plug 7 is made of elastic insulating material; under the elastic effect of the first plug 7 itself, the edge of the first plug 7 is tightly attached to the surface of the inner channel 8 to be finished, so as to avoid the gap between the edge of the first plug 7 and the surface of the inner channel 8 to be finished, and to avoid the working liquid and the gas generated by the anode from flowing out of the chamber through the edge of the first plug 7.

[0055] In the embodiment, the axial cross-sectional profile of the cathode 5 is circular, triangular, arc-shaped or polygonal, but it is ensured that when the first plug 7 and the second plug 3 are arranged in the inner channel 8, the area of the inner wall of the inner channel 8 between the first plug 7 and the second plug 3 is smaller than the surface area of the cathode 5, so that the contact area between the cathode 5 and the working liquid is larger than the contact area between the anode and the working liquid, which avoids the anode from generating too much gas and ensures the generation of plasma on the anode.

[0056] In the embodiment, the insulating liquid flushing baffle 6 is further included, and the liquid flushing baffle 6 is fixedly sleeved on the cathode 5; there is a gap between the edge of the liquid flushing baffle 6 and the inner wall of the inner channel 8, which is used for the flow of the working liquid and the gas, and the area of the side of the liquid flushing baffle 6 facing the cathode 5 is larger than the projection area of the cathode 5 on the liquid flushing baffle 6; the liquid flushing baffle 6 is used to control the liquid flushing flow field, so that the excess gas is taken out of the machining area with the working liquid, and the spark discharge caused by too much gas is avoided.

[0057] Embodiment Two

[0058] As shown in Figure 5 the embodiment, the part inner channel finishing device 100 is provided, and the part inner channel finishing device 100 of the embodiment is basically the same as that of the first embodiment, and the difference is that in the embodiment, the cathode 5 includes a plurality of circumferentially and uniformly distributed electrode pieces, and any two adjacent electrode pieces are connected to each other, the cathode 5 in the embodiment has a large surface area, so as to increase the contact area between the cathode 5 and the working liquid, which can further avoid the anode from generating too much gas and ensure the generation of plasma on the anode.

[0059] Embodiment Three

[0060] The embodiment provides a part inner channel finishing method based on the part inner channel finishing device 100 in the embodiment one or the embodiment two, and specifically comprises the following steps.

[0061] S1, the traction line 9, the first plugging head 7, the cathode 5 and the second plugging head 3 are sequentially placed into one end of the inner channel 8, and the end of the traction line 9 away from the first plugging head 7 is pulled out from the other end of the inner channel 8, and the first plugging head 7 and the second plugging head 3 have the maximum interval;

[0062] S2, the positive pole of the power supply 11 is electrically connected with the part 1;

[0063] S3, the power supply 11 is turned on, and the inner wall of the inner channel 8 between the first plugging head 7 and the second plugging head 3 is finished;

[0064] S4, after a preset time period in the step S3, the first plugging head 7 is pulled by the traction line 9, so that the first plugging head 7, the cathode 5 and the second plugging head 3 move a preset distance along the inner channel 8, and the interval between the first plugging head 7 and the second plugging head 3 is equal to the preset distance;

[0065] S5, the step S4 is repeated until the finishing of all regions in the inner channel 8 is completed;

[0066] S6, the power supply 11 is turned off, and the traction line 9, the first plugging head 7, the cathode 5 and the second plugging head 3 are taken out.

[0067] It is worth noting that the preset time period in the step S4 needs to be determined by experiment in advance, and the preset time period needs to meet that the surface of the inner channel 8 in the chamber between the first plugging head 7 and the second plugging head 3 can be finished in the preset time period.

[0068] In the description of the present application, it should be noted that the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0069] The principle and implementation mode of the present application are described by using specific examples in the present application, and the above embodiment is only used to help understand the method and core idea of the present application; meanwhile, for the general technical personnel in the field, according to the idea of the present application, the specific implementation mode and application range will be changed. In conclusion, the content of the specification should not be understood as the limitation of the present application.

Claims

1. A part internal channel finishing device characterized by: The device comprises a traction line, a power supply, a power supply line, a first sealing head, a second sealing head and a cathode, the first sealing head and the second sealing head are spaced apart and insulated, when the first sealing head is arranged in an inner channel of a part, all edges of the first sealing head are tightly fitted with inner walls of the inner channel, one end of the traction line is fixedly connected with one end of the first sealing head away from the second sealing head, one end of the power supply line is electrically connected with a negative electrode of the power supply, the other end of the power supply line is fixedly connected with the first sealing head, the power supply line passes through the second sealing head and is fixedly connected with the second sealing head, the cathode is located between the first sealing head and the second sealing head and is electrically connected with the power supply line, a liquid outlet is arranged on the first sealing head, a liquid flushing outlet is arranged on the second sealing head, and a positive electrode of the power supply is used for being electrically connected with the part. A gas outlet is arranged on the second sealing head, or a gap is formed between part of edges of the second sealing head and the inner walls of the inner channel when the second sealing head is arranged in the inner channel.

2. The part internal passage finishing device of claim 1, wherein: The first sealing head and the second sealing head are both made of elastic insulating material.

3. The part internal passage finishing device of claim 1, wherein: An axial cross-sectional profile of the cathode is circular, triangular, circular-arc or polygonal.

4. The part internal passage finishing device of claim 1, wherein: The cathode comprises a plurality of electrode pieces uniformly distributed in a circumferential direction, and any two adjacent electrode pieces are connected with each other.

5. The part internal passage finishing device of claim 1, wherein: When the first sealing head and the second sealing head are both arranged in the inner channel, an area of the inner walls of the inner channel between the first sealing head and the second sealing head is smaller than a surface area of the cathode.

6. The part internal passage finishing device of claim 1, wherein: An insulating liquid flushing baffle is further arranged, and the liquid flushing baffle is fixedly sleeved on the cathode.

7. The part internal passage finishing device of claim 6, wherein: The liquid flushing baffle is circular, a diameter of the liquid flushing baffle is smaller than a minimum diameter of a cross section of the inner channel, and an area of the liquid flushing baffle is greater than a projection area of the cathode on the liquid flushing baffle.

8. The part internal passage finishing device of claim 1, wherein: The liquid flushing outlet is communicated with a working liquid source through a liquid flushing pipe, and the liquid outlet is communicated with a working liquid recovery tank or the working liquid source through a liquid outlet pipe.

9. A method of finishing an internal passage of a part, characterized by: The device for finishing an inner channel of a part according to any one of claims 1-8 comprises the following steps: S1, sequentially placing the traction line, the first sealing head, the cathode and the second sealing head into one end of the inner channel, and making one end of the traction line away from the first sealing head pass out from the other end of the inner channel; S2, electrically connecting a positive electrode of the power supply with the part; S3, turning on the power supply to finish the inner walls of the inner channel between the first sealing head and the second sealing head; S4, after a preset time period of performing step S3, pulling the first sealing head through the traction line to make the first sealing head, the cathode and the second sealing head move a preset distance along the inner channel, and a spacing between the first sealing head and the second sealing head is equal to the preset distance; S5, repeating step S4 until finishing finishing of all regions in the inner channel; S6, turning off the power supply, and taking out the traction line, the first sealing head, the cathode and the second sealing head.

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