Quick-change fixture for plasma polishing of metal workpieces and plasma polishing method

Abstract

The application discloses a quick-change hanger for plasma polishing of metal workpieces and a plasma polishing method. The quick-change hanger comprises a hanger body, the hanger body comprising an integral head and arm part; and at least two multi-station structures, the at least two multi-station structures being symmetrically arranged on the arm part of the hanger body with the head as the center, wherein the multi-station structure comprises: a conductive part for conducting current to the polishing part of the metal workpiece; a protection part for shielding the non-polishing part of the metal workpiece; and a quick-change connector for fixing the metal workpiece on the multi-station structure, wherein the hanger body is integrally formed by a metal material resistant to corrosion and high temperature, and the surface of the arm part of the hanger body is covered with a high-temperature insulating adhesive layer.

Description

Technical Field

[0001] This invention belongs to the technical field of plasma polishing process for metal workpieces, and specifically relates to a quick-change fixture and a plasma polishing method for plasma polishing of metal workpieces. Background Technology

[0002] One type of conductive rod used in vacuum interrupter products is a stepped long shaft structure, consisting of a large end and a small end. The large end is generally a cup-shaped slotted structure, and the small end face is a central threaded hole structure. The metal workpiece is made of conductive metal material. In order to improve the performance of vacuum interrupter products, the tip of the large end of the metal workpiece and the outer circle and arc part of the large end need to be plasma polished.

[0003] In the prior art, as disclosed in Chinese patent CN223301383U, a fixture for localized plasma polishing of metal workpieces is provided. This fixture includes a body and a shield. One end of the body has a threaded connector for connecting to the central threaded hole on the small end face of the metal workpiece. The shield is fitted over the small end of the metal workpiece to achieve localized polishing. This solution utilizes a sealing groove and sealing ring designed on the end face of the threaded connector to solve the problem of inconsistent polishing caused by the plasma polishing solution entering the polishing process, thus improving the quality of localized polishing to a certain extent.

[0004] However, the existing hangers mentioned above still have significant shortcomings in actual mass production applications: 1) The clamping method of this fixture involves manually aligning a single workpiece with the threaded head of the fixture and tightening it. The operator is prone to fatigue from repeatedly tightening and unscrewing the fixture, and the loading and unloading time is long, which causes the plasma polishing equipment to be in a waiting state frequently, making it difficult to improve the utilization rate of the equipment.

[0005] 2) The connection and disassembly of the fixture to the workpiece are all done one by one, which cannot achieve rapid batch replacement and is difficult to meet the needs of modern efficient production.

[0006] In summary, there is an urgent need to develop a fixture and supporting process that can achieve multi-station batch clamping and rapid changeover to solve the technical problems of low assembly and disassembly efficiency and insufficient equipment utilization in the existing technology. Summary of the Invention

[0007] In order to overcome the shortcomings of the prior art, the present invention aims to provide a quick-change fixture and a plasma polishing method for plasma polishing of metal workpieces, which aims to solve the technical problems of low assembly and disassembly efficiency and reduced equipment utilization of existing fixtures in batch processing, and to achieve multi-station, high-efficiency, and high-quality batch plasma polishing.

[0008] To achieve the above objectives, the present invention employs the following technical solution: A first aspect of the present invention provides a quick-change fixture for plasma polishing of metal workpieces, comprising: The hanging body includes an integrally formed head and arm; and At least two multi-station structures are symmetrically arranged on the arm of the hanger body with the head as the center. The multi-station structure includes: A conductive part, the conductive part being used to conduct current to a polished portion of a metal workpiece; A protective section, said protective section being used to shield the non-polished portion of a metal workpiece; and A quick-change connector is used to fix the metal workpiece onto the multi-station structure. The hanging fixture body is integrally formed from corrosion-resistant and high-temperature-resistant metal material, and the arm surface of the hanging fixture body is covered with a high-temperature insulating adhesive layer.

[0009] In some embodiments, the conductive parts, protective parts, and quick-change connectors of the multi-station structure are detachably disposed on the arm of the fixture body, thereby facilitating the removal of the metal workpiece to be polished.

[0010] In some embodiments, the quick-change connector surface has a threaded portion corresponding to a threaded hole on the top of the metal workpiece to be polished.

[0011] In some embodiments, the protective part is made of a polymeric, acid- and alkali-resistant, high-temperature-resistant insulating material.

[0012] In some embodiments, a sealing portion is provided between the conductive portion and the protective portion to prevent accidental polishing of the non-polished portion of the metal workpiece.

[0013] In some implementations, the quick-change hanger includes eight multi-station structures, which are spaced apart on the arm of the hanger body with equal intervals around the head.

[0014] A second aspect of the present invention provides a method for plasma polishing of metal workpieces, comprising: The metal workpiece to be polished is fixed on the quick-change fixture, and the quick-change fixture is fixed on the equipment arm of the plasma polishing equipment. The metal workpiece to be polished is slowly immersed in the polishing solution for polishing treatment, resulting in a polished metal workpiece; and The polished metal workpiece is immersed in a cleaning tank for cleaning to obtain the finished metal workpiece. The quick-change hanger is the quick-change hanger described in the first aspect of the present invention.

[0015] In some embodiments, the DC voltage used for the polishing process is greater than or equal to 150V.

[0016] In some embodiments, the polishing solution comprises a salt mixture of sodium sulfate, ammonium sulfate, and ammonium citrate in a mass ratio of (12-15):(3-5):1.

[0017] In some embodiments, the metal workpiece is preheated before the polishing process, and the preheating temperature is 90-100°C for 2-3 minutes.

[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) The quick-change fixture provided by the present invention has at least two multi-station structures (preferably eight) symmetrically arranged on the arm of the fixture body with the head as the center, which can clamp multiple metal workpieces at one time, realizing batch plasma polishing. At the same time, through the cooperation of quick-change connectors and loading fixtures, operators can pre-position multiple workpieces and put on protective parts outside the equipment, and then use electric or pneumatic wrenches to quickly fasten or disassemble the fixture to all workpieces at one time. This multi-station + quick-change design completely changes the traditional single-piece manual tightening operation mode, greatly shortens the loading and unloading time, and significantly improves the utilization rate of plasma polishing equipment.

[0019] (2) Each metal workpiece has a protective part made of high-temperature and acid-alkali resistant polymer material on its non-polished part (large end), which effectively shields the non-polished area and prevents it from contacting the polishing liquid, ensuring the accuracy of local polishing. At the same time, a sealing part (sealing ring) is set between the conductive part and the protective part. When the quick-change connector is locked, the sealing ring is pressed between the surface of the hanger body arm and the end face of the protective part, forming a reliable seal, which effectively prevents the polishing liquid from seeping into the threaded connection area and the non-polished part, preventing inconsistent polishing and thread corrosion. The high-temperature insulating adhesive layer on the surface of the hanger body arm reduces stray current and power consumption, further improving the stability and economy of the polishing process.

[0020] (3) The head and arm of the fixture body are integrally molded, ensuring the overall structural strength and electrical reliability of the fixture. The multi-station structure is symmetrically arranged with the head as the center, ensuring the balance of the fixture components during polishing. The anti-detachment design of the quick-change connectors prevents bolts from being lost during frequent disassembly and assembly. The detachable design of each component allows worn parts to be replaced individually, reducing maintenance costs. The sealing part further ensures the polishing quality.

[0021] (4) The polishing method provided by this invention ensures the stability and consistency of the polishing process by optimizing a specific high-purity polishing salt formula (sodium sulfate, ammonium sulfate, and ammonium citrate mixed in a specific mass ratio). The added preheating treatment step effectively prevents equipment overload, reduces instantaneous current peaks, and is conducive to obtaining a more uniform and finer polished surface. The design of the circulating water cleaning system saves water resources and conforms to the concept of green manufacturing.

[0022] (5) Through the innovation of fixture structure and optimization of process method, this invention achieves low-cost and high-efficiency mass production while ensuring excellent local polishing quality, and has high practical value and promotion prospects. Attached Figure Description

[0023] Figure 1 This is a structural schematic diagram of the quick-change hanger according to the first embodiment of the present invention.

[0024] Figure 2 for Figure 1 A magnified view of a portion of point A in the middle.

[0025] The reference numerals in the attached figures are as follows: 11-Head; 12-Arm; 21-Conductive part; 22-Protective part; 23-Quick-change connector; 24-Sealing part; 30-Metal workpiece. Detailed Implementation

[0026] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. 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 should fall within the scope of protection of the present invention.

[0027] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0028] The present invention will now be described in further detail with reference to the accompanying drawings: See Figure 1 The first embodiment of the present invention provides a quick-change fixture for plasma polishing of metal workpieces, mainly used for partial plasma polishing of metal workpieces 30, such as the conductive rod of a vacuum interrupter. The metal workpiece 30 has a stepped long shaft structure, including a large end (the end to be polished) and a small end (the non-polished end), wherein the end face of the small end is provided with a central threaded hole for installation. The specific structure of the quick-change fixture will be described below.

[0029] Quick-change fixtures mainly consist of the fixture body and at least two multi-station structures, such as... Figure 1 As shown, the multi-station structure may include eight multi-station structures symmetrically arranged on the arm 12 of the hanger body with the head 11 of the hanger body as the center.

[0030] The mounting body is integrally formed from a metal material with good electrical conductivity, corrosion resistance, and high temperature resistance. The mounting body includes a head 11 and arms 12. The head 11 is located in the center of the mounting body and is used to connect to the power arm of the plasma polishing equipment and conduct current. The arms 12 extend symmetrically from the head 11 to both sides and are the main load-bearing structures of the mounting.

[0031] The arm 12 of the fixture body is covered with a high-temperature insulating adhesive layer to reduce stray current and energy consumption in non-working areas during polishing. The head 11 and the conductive parts of the multi-station structure (described later) are not covered with an insulating adhesive layer to ensure good conductive contact. For example, the arm 12 of the fixture body can be coated with a high-temperature insulating adhesive such as green glue or Teflon to reduce stray current and energy consumption.

[0032] Multiple multi-station structures are symmetrically arranged on the arm 12 of the fixture body with the head 11 as the center. This symmetrical arrangement helps maintain the overall balance of the fixture assembly during polishing, ensuring that the depth and orientation of each metal workpiece 30 immersed in the polishing fluid are consistent, thereby achieving a uniform polishing effect. In some embodiments, the arm 12 of the fixture body may be provided with through holes of different specifications to accommodate metal workpieces with different hole diameters.

[0033] The multi-station structure of quick-change fixtures will be described in detail below. For example... Figure 1 and Figure 2 As shown, each multi-station structure specifically includes a conductive part 21, a protective part 22, and a quick-connect connector 23.

[0034] A conductive part 21 is disposed on the arm 12 of the hanger body for electrical contact with the small end of the metal workpiece 30 and for conducting current to the large end (polished part) of the metal workpiece 30. In this embodiment, the conductive part 21 is a metal block connected to the arm 12, which has a through hole or threaded hole corresponding to the arm so that the quick-change connector 23 (described later) passes through and fixes the metal workpiece 30. The surface of the conductive part 21 is not covered with an insulating adhesive layer to ensure good electrical contact with the quick-change connector 23. The bottom surface of the conductive part 21 is also provided with an annular groove for mounting the sealing part 24 (described later).

[0035] The protective part 22 is sleeved on the outside of the small end (non-polished part) of the metal workpiece 30 to shield the non-polished part, preventing it from contacting the polishing liquid during plasma polishing, thereby achieving localized polishing. In this embodiment, the protective part 22 is a hollow cylindrical structure with one open end and one closed end, made of a high-temperature resistant and acid-alkali resistant polymer insulating material. For example, the protective part 22 can be designed and manufactured using a high-temperature resistant and acid-alkali resistant polymer material to maximize energy savings, especially electrical energy consumption. A through hole is opened at the closed end of the protective part 22 so that the quick-connect connector 23 passes through the protective part 22 and connects to the small end of the metal workpiece 30.

[0036] The quick-change connector 23 includes a cap with a diameter larger than the through hole in the arm and a rod for fixing the metal workpiece. The surface of the rod of the quick-change connector 23 has a threaded portion corresponding to the threaded hole at the small end of the metal workpiece 30. The rod of the quick-change connector 23 passes through the arm 12 of the hanger body and the conductive portion 21 of the multi-station structure, and is threadedly connected to the central threaded hole on the small end face of the metal workpiece 30 via the threaded portion, thereby fixing the metal workpiece 30 to the multi-station structure. The quick-change connector 23 has an anti-detachment design (as described above, the cap's diameter is larger than the through hole in the arm), preventing it from detaching from the arm 12 of the hanger body even when not locked, effectively avoiding loss of the quick-change connector 23 during frequent disassembly and assembly.

[0037] A sealing part 24 is also provided between the conductive part 21 and the protective part 22. In this embodiment, the sealing part 24 is a sealing ring (such as a fluororubber sealing ring), which is installed in the annular groove described above and sleeved on the rod of the quick-change connector 23. When the quick-change connector 23 is screwed down into the central threaded hole of the metal workpiece 30 and tightened, the sealing part 24 is pressed between the lower surface of the conductive part 21 and the upper end face of the protective part 22, thereby forming a seal between the conductive part 21, the protective part 22 and the quick-change connector 23, preventing polishing fluid and air bubbles from seeping into the threaded connection and non-polished areas during subsequent polishing, and ensuring the accuracy of local polishing.

[0038] The conductive part 21, protective part 22, and quick-change connector 23 of the multi-station structure are all detachably mounted on the arm 12 of the hanger body. When a component wears or ages due to long-term use, it can be replaced individually, reducing the cost of use.

[0039] During installation, the quick-change hanger is first placed horizontally via the head 11 of the hanger body. The arm of the hanger body is pre-installed with a conductive part 21, a quick-change connector 23, and a sealing part 24. After the metal workpiece 30 is fitted with the protective part 22, it is arranged on the loading fixture according to the position of the hanger body. Then, using an electric wrench, the threaded part of the quick-change connector 23 is sequentially connected to the center threaded hole at the small end of the metal workpiece 30, thereby fixing the metal workpiece 30 to the hanger body, completing the quick-change installation. During disassembly, the quick-change connector 23 is sequentially separated from the metal workpiece 30 using an electric wrench, and the protective part 22 is removed, completing the quick-change.

[0040] In actual production, two hangers are usually used alternately to perform the above operations in order to achieve quick changes, facilitate the rapid mounting and dismounting of equipment, and improve equipment utilization.

[0041] The second embodiment of the present invention provides a method for plasma polishing of metal workpieces using the quick-change fixture described in the first embodiment, specifically including the following steps: S1: Fix the metal workpiece to be polished onto the quick-change fixture, and then fix the quick-change fixture onto the equipment arm of the plasma polishing equipment.

[0042] Specifically, multiple metal workpieces 30 (e.g., eight) are first placed accurately in the corresponding positioning holes of a dedicated loading fixture with the smaller end facing up and the larger end facing down. This loading fixture ensures that all metal workpieces 30 maintain a uniform posture and spacing. Then, a protective part 22 (a protective cap made of high-polymer acid and alkali resistant, high-temperature resistant insulating material) is fitted over the larger end of each metal workpiece 30.

[0043] Next, the quick-change fixture body is placed above the loading fixture, aligning the multiple quick-change connectors 23 on the fixture body with the small-end center threaded holes of the multiple metal workpieces 30. By connecting the threaded portions of the quick-change connectors 23 to the small-end center threaded holes of the metal workpieces 30, the operator uses an electric or pneumatic wrench to simultaneously and securely fasten the multiple metal workpieces 30 to the fixture, ensuring a firm fixation and preventing them from falling off during polishing, thus forming a complete fixture assembly. The complete fixture assembly is then mounted on the arm of the plasma polishing equipment via the head 11 of the fixture body.

[0044] S2: Slowly immerse the metal workpiece to be polished into the polishing liquid for polishing treatment to obtain the polished metal workpiece.

[0045] Specifically, after the equipment is started, the hanging arm drives the hanging fixture assembly to slowly descend. Before the large end of the metal workpiece 30 is fully immersed in the polishing liquid, it is preheated above the surface of the polishing liquid to reduce the instantaneous current peak at the start of polishing, better prevent equipment current overload, reduce power consumption, and improve the polishing quality of the metal workpiece.

[0046] After preheating, the fixture assembly continues to descend, completely immersing the large end of the metal workpiece 30 in the pre-prepared polishing solution. The polishing solution contains a salt mixture composed of sodium sulfate, ammonium sulfate, and ammonium citrate in a mass ratio of (12-15):(3-5):1, preferably using chemical reagent salts with a purity of ≥99.98%. Then, a DC voltage greater than or equal to 150V is applied to the metal workpiece 30 through the head 11, arm 12, and conductive part 21 of the multi-station structure of the fixture body for plasma polishing. The polishing time can be set on the equipment according to the surface roughness requirements of the metal workpiece.

[0047] During this process, due to the shielding effect of the protective part 22 and the sealing effect of the sealing part 24, the polishing liquid cannot come into contact with the small end and threaded hole of the metal workpiece 30, and only the large end is subjected to efficient plasma polishing.

[0048] S3: Immerse the polished metal workpiece in a cleaning tank for cleaning to obtain the finished metal workpiece.

[0049] Specifically, after polishing, the entire fixture assembly is removed from the polishing equipment and immersed in a cleaning tank. The cleaning tank consists of a coarse cleaning tank and a fine cleaning tank arranged sequentially. The fine cleaning tank is connected to an inlet pipe, and the coarse cleaning tank is connected to an outlet pipe; the two tanks are connected by an intermediate water pipe. Water from the fine cleaning tank flows into the coarse cleaning tank through the intermediate water pipe, and water from the coarse cleaning tank is discharged through the outlet pipe, forming a circulating water flow. The coarse cleaning tank can also replenish water to the polishing tank as needed, and the fine cleaning tank can replenish water itself, ensuring that the cleaned parts use circulating water and improving the cleaning quality after polishing.

[0050] The operator first immerses the entire fixture assembly in a rough cleaning tank and performs a first rinse with circulating water to remove most of the residual polishing liquid from the workpiece surface. Then, it is transferred to a fine cleaning tank for a second fine rinse with cleaner circulating water.

[0051] After cleaning, use an electric or pneumatic wrench to rotate all quick-change connectors 23 in the opposite direction to remove them, and remove the multiple polished metal workpieces 30 from the fixture body as a whole, and take them out from the protective part 22 to obtain the finished metal workpieces.

[0052] Subsequently, post-processing can be performed on the finished metal workpieces. The removed metal workpiece 30 is placed on a drying rack, and the surface moisture is dried using a high-pressure air gun, completing the plasma polishing process. The quick-change fixture allows for immediate assembly with the next batch of workpieces pre-positioned on another loading fixture, enabling continuous and efficient mass production.

[0053] Therefore, the multi-station + quick-change design of the quick-change fixture provided by this invention completely changes the traditional single-piece manual tightening operation mode, greatly shortens the loading and unloading time, effectively solves the problem that fatigue is easily caused by repeated tightening and unscrewing actions in batch processing, and the slow speed of manual operation leads to poor connection between loading and unloading to plasma polishing equipment, affecting the utilization rate of the equipment, and significantly improves the utilization rate of plasma polishing equipment.

[0054] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A quick-change fixture for plasma polishing of metal workpieces, characterized in that, The quick-change hanger includes: The hanging body includes an integrally formed head and arm; and At least two multi-station structures are symmetrically arranged on the arm of the hanger body with the head as the center. The multi-station structure includes: A conductive part, the conductive part being used to conduct current to a polished portion of the metal workpiece; A protective section, the protective section being used to shield the non-polished portion of the metal workpiece; and A quick-change connector is used to fix the metal workpiece onto the multi-station structure. The hanging fixture body is integrally formed from corrosion-resistant and high-temperature-resistant metal material, and the arm surface of the hanging fixture body is covered with a high-temperature insulating adhesive layer.

2. The quick-change hanger according to claim 1, characterized in that, The conductive part, the protective part, and the quick-change connector of the multi-station structure are detachably disposed on the arm of the hanger body, thereby facilitating the removal of the metal workpiece to be polished.

3. The quick-change hanger according to claim 1, characterized in that, The quick-change connector has a threaded portion on its surface that corresponds to the threaded hole on the top of the metal workpiece to be polished.

4. The quick-change hanger according to claim 1, characterized in that, The protective part is made of a high-molecular-weight, acid- and alkali-resistant, high-temperature-resistant insulating material.

5. The quick-change hanger according to claim 1, characterized in that, A sealing portion is provided between the conductive portion and the protective portion, the sealing portion being used to prevent accidental polishing of the non-polished portion of the metal workpiece.

6. The quick-change hanger according to claim 1, characterized in that, The quick-change hanger includes eight multi-station structures, which are spaced at equal intervals on the arm of the hanger body with the head as the center.

7. A method for plasma polishing of metal workpieces, characterized in that, The method includes: The metal workpiece to be polished is fixed on the quick-change fixture, and the quick-change fixture is fixed on the equipment arm of the plasma polishing equipment. The metal workpiece to be polished is slowly immersed in the polishing solution for polishing treatment, resulting in a polished metal workpiece; and The polished metal workpiece is immersed in a cleaning tank for cleaning to obtain the finished metal workpiece. The quick-change hanger is the quick-change hanger according to any one of claims 1 to 6.

8. The method according to claim 7, characterized in that, The DC voltage used in the polishing process is greater than or equal to 150V.

9. The method according to claim 7, characterized in that, The polishing solution contains a salt mixture, which is a mixture of sodium sulfate, ammonium sulfate and ammonium citrate in a mass ratio of (12-15):(3-5):

1.

10. The method according to claim 7, characterized in that, Before the polishing process, the metal workpiece is preheated at a temperature of 90-100°C for 2-3 minutes.

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