CN113151752A - Copper rod with wear-resistant surface and production method thereof - Google Patents

Copper rod with wear-resistant surface and production method thereof Download PDF

Info

Publication number
CN113151752A
CN113151752A CN202110385463.4A CN202110385463A CN113151752A CN 113151752 A CN113151752 A CN 113151752A CN 202110385463 A CN202110385463 A CN 202110385463A CN 113151752 A CN113151752 A CN 113151752A
Authority
CN
China
Prior art keywords
copper rod
copper
wear
temperature
resistant surface
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
CN202110385463.4A
Other languages
Chinese (zh)
Inventor
周涛
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Jiangxi Zhongsheng Metal Co ltd
Original Assignee
Jiangxi Zhongsheng Metal Co ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Jiangxi Zhongsheng Metal Co ltd filed Critical Jiangxi Zhongsheng Metal Co ltd
Priority to CN202110385463.4A priority Critical patent/CN113151752A/en
Publication of CN113151752A publication Critical patent/CN113151752A/en
Withdrawn legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C49/00—Alloys containing metallic or non-metallic fibres or filaments
    • C22C49/02—Alloys containing metallic or non-metallic fibres or filaments characterised by the matrix material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/16—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling wire rods, bars, merchant bars, rounds wire or material of like small cross-section
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C37/00—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape
    • B21C37/04—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape of bars or wire
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
    • C22B9/10—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals with refining or fluxing agents; Use of materials therefor, e.g. slagging or scorifying agents
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C47/00—Making alloys containing metallic or non-metallic fibres or filaments
    • C22C47/08—Making alloys containing metallic or non-metallic fibres or filaments by contacting the fibres or filaments with molten metal, e.g. by infiltrating the fibres or filaments placed in a mould
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C49/00—Alloys containing metallic or non-metallic fibres or filaments
    • C22C49/14—Alloys containing metallic or non-metallic fibres or filaments characterised by the fibres or filaments
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B5/00—Non-insulated conductors or conductive bodies characterised by their form
    • H01B5/02—Single bars, rods, wires, or strips

Abstract

The invention discloses a copper rod with a wear-resistant surface, which comprises the following raw materials of 2-5% of graphite, 3-8% of nickel-copper alloy, 2-5% of magnesium, 2-5% of glass fiber and the balance of pure copper. The ink has high melting point, the heat conductivity coefficient is reduced along with the temperature rise, the heat resistance of the copper rod can be improved, the wear resistance of the glass fiber and the nickel-copper alloy is good, and the wear resistance of the copper rod can be improved.

Description

Copper rod with wear-resistant surface and production method thereof
Technical Field
The invention relates to the technical field of copper rods, in particular to a copper rod with a wear-resistant surface and a production method thereof.
Background
The copper rod is a necessary blank for producing copper wires such as electric wires and cables, enameled wires, electronic wires and the like, and the copper wires are one of important basic materials in the industries of electronics, electricity, communication and the like.
With the development of the electrical industry, the requirements on the market-level materials such as cables and wires and the purity are higher and higher, the copper rod is widely used for guiding electrical cables, the existing copper rod mainly adopts a continuous casting and rolling process, and the steps comprise feeding, melting, oxidation reduction and slagging-off, continuous casting and rolling.
The copper wire rods of the electric wires, the cables, the enameled wires, the electronic wires and the like have wide application range, different application environments and high requirements on wear resistance and heat resistance, the copper rod is used as an essential blank, and the wear resistance, the mechanical property and the fire resistance of the copper rod determine the performance of the copper wire.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention provides a copper rod with a wear-resistant surface and a production method thereof.
In order to solve the technical problems, the invention adopts the following technical scheme: a copper rod with a wear-resistant surface comprises 2-5% of graphite, 3-8% of nickel-copper alloy (the nickel-copper alloy is an alloy material comprising three metals of 60% of nickel, 33% of copper and 6.5% of iron), 2-5% of magnesium, 2-5% of glass fiber and the balance of pure copper;
the graphite has high melting point, is burnt by an ultra-high temperature electric arc, has small weight loss and small thermal expansion coefficient, the thermal conductivity coefficient is reduced along with the rise of the temperature, and even under the ultra-high temperature, the graphite becomes a heat insulator;
the glass fiber is an inorganic non-metallic material with excellent performance, and has good insulativity, strong heat resistance, good corrosion resistance and high mechanical strength;
the nickel-copper alloy has good room temperature mechanical property and high temperature strength, good corrosion resistance and wear resistance, easy processing and no magnetism.
A production method of a copper rod with a wear-resistant surface comprises the following steps:
1) putting the raw materials into a melting furnace, and completely melting the raw materials to obtain a raw material solution;
2) under the condition of 200-290 ℃, the raw material liquid is put into a nitrite solution with the weight ratio of 1:3 and stirred, mixed metal liquid is obtained after the preset time, and cast to obtain cast ingots, wherein the sulfite has a strong reducing agent and can be used for removing redundant oxygen, preventing metal from being oxidized and preventing the metal from being oxidized to form oxides in the process of preparing the copper rod, so that the mechanical property and the fire resistance of the copper rod are influenced;
3) carrying out hot rolling treatment-cold rolling treatment on the cast ingot in sequence to obtain a primary copper rod;
4) and (3) putting the preliminary copper rod into an antioxidant solution, soaking for 30-50min, taking out, and performing plasticizing treatment to obtain the copper rod.
Preferably, in the hot rolling treatment, the ingot is subjected to primary rough rolling at the temperature of 350-.
Preferably, in the cold rolling treatment, when the cooling speed is 5 ℃/s and the temperature is cooled to 500-400 ℃, the obtained finish rolling copper strip is subjected to a cold rolling treatment process, and when the cooling speed is 5 ℃/s and the temperature is cooled to 400-300 ℃, the cold rolled copper strip is subjected to stretch bending straightening to obtain a primary copper rod which is a final product.
Preferably, the antioxidant comprises a mixture of 1: 1.5, the tea polyphenol has good oxidation resistance, and the sodium pyrosulfite can be used for enhancing the oxidation resistance of the tea polyphenol under the synergistic action.
Compared with the prior art, the invention has the beneficial effects that:
1. the ink has high melting point, the heat conductivity coefficient is reduced along with the temperature rise, the heat resistance of the copper rod can be improved, the wear resistance of the glass fiber and the nickel-copper alloy is good, and the wear resistance of the copper rod can be improved;
2. the precision is ensured and the operation is convenient through multiple times of rolling;
3. the sulfite has a strong reducing agent, and can be used for removing redundant oxygen, preventing metal from being oxidized and preventing the metal from being oxidized to form oxide in the process of preparing the copper rod, thereby influencing the mechanical property and the fire resistance of the copper rod.
Detailed Description
The present invention will be described in detail with reference to examples.
Example 1
The invention provides a copper rod with a wear-resistant surface, which comprises the raw material components of 2% of graphite, 3% of nickel-copper alloy, 2% of magnesium, 2% of glass fiber and the balance of pure copper.
Example 2
A copper rod with a wear-resistant surface comprises 3% of graphite, 5% of nickel-copper alloy, 3% of magnesium, 3% of glass fiber and the balance of pure copper.
Example 3
A copper rod with a wear-resistant surface comprises raw material components of 5% of graphite, 8% of nickel-copper alloy, 5% of magnesium, 5% of glass fiber and the balance of pure copper.
Comparative example 1
A wear-resistant copper rod comprises 2% of zinc, 5% of magnesium, 4% of manganese and the balance of pure copper.
The copper rods prepared by the same preparation method in example 1, example 2, example 3 and comparative example are compared, and the specific data are shown in Table 1;
the copper rods obtained by the methods of example 1, example 2, example 3 and comparative example 1 were subjected to an acetate spray test, the specific test being shown in table 1;
the preparation method comprises the following steps: and (3) putting the raw materials into a melting furnace, completely melting the raw materials to obtain molten metal, and casting the molten metal to obtain the copper rod.
TABLE 1
Example 1 Example 2 Example 3 Comparison ofExample 1
Tensile strength/Ma 253 274 295 228
Limit of fire resistance 91min 110min 123min 70min
Hardness HV 108 117 126 91
Therefore, the embodiment 3 is an optimal scheme, the graphite has high melting point, the heat conductivity coefficient is reduced along with the temperature rise, the heat resistance of the copper rod can be improved, the wear resistance of the glass fiber and the nickel-copper alloy is good, and the wear resistance of the copper rod can be improved.
Example 4
A production method of a copper rod with a wear-resistant surface comprises the following steps:
1) putting the raw materials into a melting furnace, and completely melting the raw materials to obtain a raw material solution;
2) under the condition of 200 ℃, putting the raw material liquid into a nitrite solution with the weight ratio of 1:3, stirring, presetting time to obtain mixed metal liquid, casting the mixed metal liquid to obtain a cast ingot, wherein sulfite has a strong reducing agent and can be used for removing redundant oxygen to prevent coumarin from being oxidized;
3) sequentially carrying out hot rolling treatment (rolling the ingot at the temperature of 650 ℃) -cold rolling treatment (naturally cooling the rolled ingot to the normal temperature of 30 ℃) on the ingot to obtain a primary copper rod;
4) and (3) placing the preliminary copper rod into an antioxidant solution to be soaked for 30min, wherein the antioxidant comprises the following components in percentage by weight of 1: 1.5, taking out the tea polyphenol and sodium pyrosulfite, and performing plasticizing treatment to obtain the copper rod.
Example 5
A production method of a copper rod with a wear-resistant surface comprises the following steps:
1) putting the raw materials into a melting furnace, and completely melting the raw materials to obtain a raw material solution;
2) under the condition of the temperature of 270 ℃, the raw material liquid is put into a nitrite solution with the weight ratio of 1:3 and stirred, mixed metal liquid is obtained after preset time, and cast ingot is obtained after the mixed metal liquid is cast, wherein sulfite has a strong reducing agent and can be used for removing redundant oxygen to avoid coumarin from being oxidized;
3) sequentially carrying out hot rolling treatment (rolling the ingot at the temperature of 650 ℃) -cold rolling treatment (naturally cooling the rolled ingot to the normal temperature of 30 ℃) on the ingot to obtain a primary copper rod;
4) and (3) placing the preliminary copper rod into an antioxidant solution to be soaked for 40min, wherein the antioxidant comprises the following components in percentage by weight of 1: 1.5, taking out the tea polyphenol and sodium pyrosulfite, and performing plasticizing treatment to obtain the copper rod.
Example 6
A production method of a copper rod with a wear-resistant surface comprises the following steps:
1) putting the raw materials into a melting furnace, and completely melting the raw materials to obtain a raw material solution;
2) under the condition of 290 ℃ of temperature, the raw material liquid is put into a nitrite solution with the weight ratio of 1:3 and stirred, mixed metal liquid is obtained after preset time, and cast ingot is obtained by casting the mixed metal liquid, wherein sulfite has a strong reducing agent and can be used for removing redundant oxygen and avoiding coumarin from being oxidized;
3) sequentially carrying out hot rolling treatment (rolling the ingot at the temperature of 650 ℃) -cold rolling treatment (naturally cooling the rolled ingot to the normal temperature of 30 ℃) on the ingot to obtain a primary copper rod;
4) and (3) placing the preliminary copper rod into an antioxidant solution to be soaked for 50min, wherein the antioxidant comprises the following components in percentage by weight of 1: 1.5, taking out the tea polyphenol and sodium pyrosulfite, and performing plasticizing treatment to obtain the copper rod.
Comparative example 2
A production method of a wear-resistant copper rod comprises the steps of putting the raw materials in the comparative example 1 into a melting furnace, obtaining molten metal after the raw materials are completely melted, and casting the molten metal to obtain the copper rod.
The copper rods prepared in example 4, example 5, example 6 and comparative example 2 were compared, and the specific data are shown in table 2:
TABLE 2
Example 4 Example 5 Example 6 Comparative example 2
Tensile strength/Ma 301 324 337 253
Limit of fire resistance 129min 148min 169min 81min
Hardness HV 130 139 147 106
As can be seen from Table 2, the optimal scheme is shown in example 6, and when the copper rod is prepared according to comparative example 2, the raw material metal liquid is not subjected to primary antioxidant treatment after smelting, and after the copper rod is obtained, the copper rod is also subjected to antioxidant treatment, so that the surface of the copper rod is prevented from being oxidized, losing luster and affecting performance.
Example 7
This embodiment is substantially the same as embodiment 6 except that:
in the hot rolling treatment, the cast ingot is subjected to first rough rolling at the temperature of 350 ℃, after the rough rolling is finished, the temperature is heated to 410 ℃ at the heating speed of 3 ℃/s, then the finish rolling is carried out, after the finish rolling is finished, the temperature is heated to 600 ℃ at the heating speed of 4 ℃/s, then the second finish rolling is carried out, after the finish rolling is finished, the temperature is kept for 30min, the cast ingot is taken out, a finish rolling copper rod is obtained, in the cold rolling treatment, the temperature is cooled to 500 ℃ at the cooling speed of 5 ℃/s, the obtained finish rolling copper strip is subjected to a cold rolling treatment process, and then the cold rolled copper strip is subjected to stretch bending and straightening when the temperature is cooled to 400 ℃ at the cooling speed of 5 ℃/s, so that a primary copper rod is obtained.
The copper rods prepared in example 6 and example 7 were compared and the specific data are shown in table 3:
TABLE 3
Example 6 Example 7
Tensile strength/Ma 337 342
Limit of fire resistance 169min 187min
Hardness HV 147 158
As can be seen from table 3, the compression resistance, fire resistance and hardness of example 7 are all greater than those of example 6, and thus, by rolling for a plurality of times, the precision and convenient operation can be ensured, the temperature of each rolling is strictly controlled, the internal structure of the copper strip is also changed along with the gradual rise of the temperature, the gap between the metals can be reduced, the adhesion between the metals is increased, the mechanical strength of the copper strip is increased, the cooling speed and temperature are strictly controlled, the activity of the metals is reduced, and the hardness and heat resistance of the copper strip are increased.
The above additional technical features can be freely combined and used in superposition by those skilled in the art without conflict.
The above examples only show some embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the patent and protection scope of the present invention should be subject to the appended claims.

Claims (5)

1. The copper rod with wear-resistant surface is characterized by comprising the following raw materials of 2-5% of graphite, 3-8% of nickel-copper alloy, 2-5% of magnesium, 2-5% of glass fiber and the balance of pure copper.
2. A method of producing a surface wear resistant copper rod as claimed in claim 1, comprising the steps of:
1) putting the raw materials into a melting furnace, and completely melting the raw materials to obtain a raw material solution;
2) under the condition of the temperature of 200-290 ℃, the raw material liquid is put into a nitrite solution with the weight ratio of 1:3 and stirred, mixed molten metal is obtained after the preset time, and the mixed molten metal is cast to obtain a cast ingot;
3) carrying out hot rolling treatment-cold rolling treatment on the cast ingot in sequence to obtain a primary copper rod;
4) and (3) putting the preliminary copper rod into an antioxidant solution, soaking for 30-50min, taking out, and performing plasticizing treatment to obtain the copper rod.
3. The method for producing a copper rod with a wear-resistant surface as claimed in claim 2, wherein the hot rolling treatment comprises a first rough rolling of the ingot at a temperature of 350-.
4. The method for producing a copper rod with a wear-resistant surface as claimed in claim 3, wherein in the cold rolling treatment, the obtained finish-rolled copper strip is subjected to a cold rolling treatment process when the temperature is cooled to 400 ℃ of 500-.
5. The method of claim 2, wherein the antioxidant comprises the following components in a weight ratio of 1: 1.5 tea polyphenols and sodium pyrosulfite.
CN202110385463.4A 2021-04-10 2021-04-10 Copper rod with wear-resistant surface and production method thereof Withdrawn CN113151752A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202110385463.4A CN113151752A (en) 2021-04-10 2021-04-10 Copper rod with wear-resistant surface and production method thereof

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202110385463.4A CN113151752A (en) 2021-04-10 2021-04-10 Copper rod with wear-resistant surface and production method thereof

Publications (1)

Publication Number Publication Date
CN113151752A true CN113151752A (en) 2021-07-23

Family

ID=76889807

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202110385463.4A Withdrawn CN113151752A (en) 2021-04-10 2021-04-10 Copper rod with wear-resistant surface and production method thereof

Country Status (1)

Country Link
CN (1) CN113151752A (en)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5017250A (en) * 1989-07-26 1991-05-21 Olin Corporation Copper alloys having improved softening resistance and a method of manufacture thereof
CN1502131A (en) * 2000-12-28 2004-06-02 因芬尼昂技术北美公司 Self-passivating Cu laster fuse
CN105778406A (en) * 2016-03-18 2016-07-20 华南理工大学 Automotive copper-based powder metallurgy composite friction material and manfuacturing method thereof
CN108859302A (en) * 2018-06-22 2018-11-23 浙江阿路佑邦新材料科技有限公司 A2 grades of fire prevention copper composite plates and its production method

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5017250A (en) * 1989-07-26 1991-05-21 Olin Corporation Copper alloys having improved softening resistance and a method of manufacture thereof
CN1502131A (en) * 2000-12-28 2004-06-02 因芬尼昂技术北美公司 Self-passivating Cu laster fuse
CN105778406A (en) * 2016-03-18 2016-07-20 华南理工大学 Automotive copper-based powder metallurgy composite friction material and manfuacturing method thereof
CN108859302A (en) * 2018-06-22 2018-11-23 浙江阿路佑邦新材料科技有限公司 A2 grades of fire prevention copper composite plates and its production method

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
张兰芳 著: "《碱激发矿渣水泥和混凝土》", 31 August 2018, 西南交通大学出版社 *
李宏磊 等: "《铜加工生产技术问答》", 31 January 2008, 冶金工业出版社 *
罗宇亮 编著: "《输电线路穿越草原保护区施工环水保研究》", 31 July 2018, 云南美术出版社 *

Similar Documents

Publication Publication Date Title
CN112877579B (en) Non-equal atomic ratio high-entropy alloy and method for preparing wire by using same
CN102851527B (en) Copper-silver-magnesium alloy contact wire and preparation method thereof
CN111519116B (en) Preparation method of large-length solderless copper-chromium-zirconium contact line
IE43712B1 (en) Wires of an a1-mg-si-alloy
CN111926214B (en) Free-cutting lead brass bar with excellent cold machining plasticity and preparation method thereof
CN110484768B (en) High-strength, high-conductivity and heat-resistant copper-chromium alloy material and preparation process thereof
CN102021295B (en) Cold-rolling steel belt for flux-cored wire and manufacture method thereof
CN111778427A (en) Preparation method of CuNiSi alloy wire for electric connector
CN101654749A (en) Easily-cutting brass and processing method of strips thereof
CN114107834B (en) High-strength iron-nickel-molybdenum alloy wire and low-cost preparation method thereof
CN109504865A (en) It is applicable in the high-strength CTB alloy shaped silk and preparation method of electrically conductive elastic component
CN105543533A (en) High-strength high-conductivity Cu-Mg alloy and preparation method thereof
CN112264732A (en) Welding wire for copper/steel dissimilar welding, preparation method of welding wire and copper/steel dissimilar welding method
CN113151752A (en) Copper rod with wear-resistant surface and production method thereof
CN115261666B (en) Lead-free high-strength high-conductivity beryllium bronze bar and manufacturing method and application thereof
CN101525731B (en) Cu-Fe original-position compound copper base material and preparation method thereof
CN113755672A (en) High-precision copper alloy flat wire production process
NO753306L (en)
CN109504871A (en) It is applicable in the high strength titanium copper alloy silk material and manufacturing method of electrically conductive elastic component
CN114959351B (en) Copper-silver alloy wire rod and preparation method and application thereof
CN115852187B (en) Copper-zirconium alloy conducting bar for traction motor rotor and preparation method thereof
CN117403096B (en) High-strength high-conductivity high-temperature-resistant copper-zirconium alloy material and preparation method thereof
JPH06240426A (en) Production of high strength copper alloy trolley wire
JP2570559B2 (en) Manufacturing method of copper alloy trolley wire and suspension wire
CN113088751A (en) High-toughness copper strip and production method thereof

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
WW01 Invention patent application withdrawn after publication
WW01 Invention patent application withdrawn after publication

Application publication date: 20210723