A method for distinguishing copper grades for enameled wire

Abstract

The present invention relates to a method for distinguishing the copper grade for enameled wire, including Vickers hardness measurement, powder loss amount and copper powder particle morphology determination, limit torsion measurement and fracture determination and metallographic spectrum analysis. The method for distinguishing the copper grade for enameled wire of the present invention can quickly and accurately distinguish high-speed copper from ordinary copper by detection during the incoming material inspection stage. The method of the present invention is easy to operate and understand, the operation process is simple and clear, it is improved on the basis of national standards, has strong versatility, accurate judgment of detection results, and low cost. The method of the present invention can guide the graded use of copper rods for enameled wire production, and avoid a large amount of losses caused by abnormal quality of the produced batch of copper wires or non-distribution and use according to demand.

Description

Technical Field

[0001] The invention belongs to the technical field of enameled wires, and in particular relates to a method for distinguishing copper grades used for enameled wires. Background Art

[0002] Copper rod is one of the main raw materials for enameled copper wire and is used as a conductor in enameled wire. In the enameled wire industry, copper rod is mainly used in the wire drawing process at the head end, and the 8mm diameter copper rod is processed and drawn into wire cores of various specifications. According to the different painting processes, the production machines of enameled wire can be divided into mold machines and felt machines. Since the mold machine has a relatively fast production speed, it is also called a high-speed machine.

[0003] High-speed copper mainly refers to the copper used for enameled wire produced by mold machines. The production speed, painting method, production process and difficulty of the production process of high-speed machines in the process of producing enameled wire are different from those of ordinary machines; high-speed machines have fast production speeds, and the painting adopts the mold painting method. The production process is more than that of ordinary machines (joint drawing, etc.), so the requirements for the selected copper are also relatively high. Generally, we define this copper as high-speed copper. Ordinary machines basically use the painting method of felt painting. The production speed and process are less than those of high-speed machines, and the surface smoothness of bare copper wire is not as high as that of high-speed machines. Therefore, the copper used is defined as ordinary copper. High-speed copper is superior to ordinary copper in elongation, impurity content, and surface smoothness of copper wire during wire drawing. In terms of quality, cost, and use efficiency, high-speed machine copper is at least one level higher than ordinary machine copper. Therefore, in the production process of enameled wire, different grades of copper rods can be used according to the use requirements to save costs and improve production efficiency.

[0004] At present, the industry does not have a method to quickly and accurately distinguish and determine high-speed copper from ordinary copper. It can only be distinguished based on the installed online detector. At this time, the copper rod has been drawn from a diameter of 8mm to a semi-finished product of about 2mm. If the quality of this batch of copper materials is unqualified, the enameled wire produced will have many defects such as pinholes and lint. The online detector will alarm, and production cannot continue, seriously affecting product quality and production efficiency. If it is unqualified, a large number of semi-finished products will be scrapped. Therefore, the current method of distinguishing copper rod grades in the industry is relatively simple and time-consuming. It is urgent to find a method that can quickly detect and accurately and reliably distinguish the copper grade for enameled wire, so that it can be distinguished in time during the inspection of incoming materials, guide the production and use of materials, and avoid the abnormal quality of the batch of copper wire produced or the non-distribution and use according to demand, resulting in a large number of losses.

[0005] In view of the above reasons, the present invention is proposed. Summary of the invention

[0006] In order to solve the above problems existing in the prior art, the present invention provides a method for distinguishing the copper grade for enameled wire. The method of the present invention can quickly and accurately distinguish high-speed copper from ordinary copper, and has simple operation, strong versatility and low cost.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] A method for distinguishing the copper grade for enameled wire includes Vickers hardness measurement, powder loss amount and copper powder particle morphology determination, limit torsion measurement and fracture determination and metallographic spectrum analysis.

[0009] The method of the present invention is improved on the basis of national standards and has strong versatility. High-speed copper and ordinary copper can be judged only when all the properties of Vickers hardness measurement, powder loss amount and copper powder particle morphology determination, limit torsion measurement and fracture determination and metallographic spectrum analysis meet the requirements.

[0010] Furthermore, the method specifically comprises the following steps:

[0011] (1) Vickers hardness test: The Vickers hardness of the enameled wire to be distinguished is measured with copper. The Vickers hardness test value is divided into two intervals, A and B, where A = 95-105 HV, B < 95 HV or > 105 HV;

[0012] (2) Determination of the amount of powder loss and the morphology of copper powder particles: The enameled wire to be distinguished is twisted forward and backward for many times, and the copper powder is collected below. The morphology of the copper powder is observed under a microscope. The mass of the copper powder is divided into two intervals, C and D. Among them, C≤2.2mg, the single copper powder particle is large, the length and width uniformity is relatively good, and the number per unit area is relatively small. D>2.2mg, the single copper powder particle is small, the length and width uniformity is poor, and the number per unit area is relatively large;

[0013] (3) Limit torsion measurement and fracture determination: The enameled copper wire to be distinguished is subjected to multiple forward and reverse torsion, and the number of reverse rotations when the copper breaks is recorded and the state of the copper fracture surface is observed. The number of reverse rotations is divided into two intervals, E and F, where E = 23-25 ​​rotations and F = 26-30 rotations. The fracture surface state is divided into G and H. G means that there are obvious protruding burrs and the fracture surface is uneven, and H means that the fracture surface is even after the copper rod breaks, without obvious burrs.

[0014] (4) Metallographic analysis: The copper enameled wire to be distinguished is subjected to metallographic observation under a metallographic microscope. The lattice distribution is divided into I and J. Among them, I means that the single unit cell volume is small, the unit cell distribution uniformity is poor, and the density is high. J means that the single unit cell volume is large, the unit cell distribution uniformity is good, and the density is poor.

[0015] (5) Determine the copper grade based on the results of steps (1)-(4).

[0016] Furthermore, when the copper detection performance of the enameled wire to be distinguished is at ACEGI, it is high-speed copper, and when it is at BDFHJ, it is ordinary copper.

[0017] Furthermore, when the Vickers hardness is measured, the experimental force value is 0.3 kgf, the holding time is 10 s, the length of the copper enameled wire to be distinguished is 2 cm, the compression sample is tested three times, and the average value is taken.

[0018] Furthermore, the amount of powder loss and the shape of copper powder particles were determined by 20 turns of forward and reverse twisting at a speed of 60 r / min.

[0019] Furthermore, the surface of the enameled wire to be distinguished is wiped clean with ethanol before being weighed with copper.

[0020] Furthermore, when determining the amount of powder loss and the morphology of copper powder particles, the length of the copper used for the enameled wire to be distinguished is 31 cm.

[0021] Furthermore, the limit torsion measurement and fracture judgment were performed with 30 forward rotations and 40 reverse rotations at a speed of 90 r / min.

[0022] Furthermore, the length of the copper used for the enameled wire to be distinguished during metallographic analysis is 2 cm.

[0023] Furthermore, during the metallographic analysis, the enameled wire to be distinguished is ground and polished with copper, and ammonia water is applied to the polished surface.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The method for distinguishing the copper grade for enameled wire of the present invention can quickly and accurately distinguish high-speed copper from ordinary copper by testing in the incoming material inspection stage. The method of the present invention is easy to operate and understand, the operation process is simple and clear, it is improved on the basis of the national standard, has strong versatility, accurate judgment of the test result, and low cost. The method of the present invention can guide the graded use of copper rods for enameled wire production, and avoid a large amount of losses caused by abnormal quality of the produced batch copper wires or non-distribution and use according to demand. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] 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 or the description of the prior art 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.

[0027] Figure 1 This is a particle morphology diagram of copper powder of sample No. 1 in Example 1 of the present invention;

[0028] Figure 2 This is a particle morphology diagram of copper powder of sample No. 2 in Example 1 of the present invention;

[0029] Figure 3 This is a fracture diagram of the No. 1 sample during the limit torsion measurement in Example 1 of the present invention;

[0030] Figure 4 This is a fracture diagram of the No. 2 sample during the limit torsion measurement in Example 1 of the present invention;

[0031] Figure 5 It is the metallographic spectrum of test No. 1 in Example 1 of the present invention;

[0032] Figure 6 This is the metallographic spectrum of test No. 2 in Example 1 of the present invention. DETAILED DESCRIPTION

[0033] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0034] Example 1

[0035] This embodiment takes a high-speed copper and a common copper as examples for explanation:

[0036] 1. First, take samples: cut two copper rods of about 100 cm in length according to the inspection requirements, one for high-speed copper and the other for ordinary copper. Try to take straighter copper materials to facilitate straightening.

[0037] 2. Straighten: After sampling, use a wooden hammer to straighten the copper rod in the laboratory, but be careful not to use too much force;

[0038] 3. According to the inspection requirements of different properties, copper rod samples are cut into lengths. The lengths for Vickers hardness and metallographic analysis are both 2 cm. The lengths for powder loss and copper powder particle morphology determination, limit torsion measurement and fracture determination are all 31 cm. The two coppers are named No. 1 and No. 2 respectively.

[0039] The specific method to distinguish the copper grade of enameled wire is as follows:

[0040] (1) Vickers hardness determination: The cut No. 1 and No. 2 samples were ground and polished to make smooth and level samples, which were placed on a Vickers hardness tester for compression testing. The test was conducted three times with an experimental force of 0.3 kgf and a holding time of 10 s. The indentation was measured using the Vickers hardness tester measurement system, and the distances D1 and D2 were manually measured for data testing to obtain the hardness test data. The specific hardness values ​​are shown in Table 1.

[0041] Table 1

[0042]

[0043] (2) Determination of powder loss and copper powder particle morphology:

[0044] Wrap the 30mm at both ends of samples No. 1 and No. 2 with transparent tape, wipe the middle 250mm with a rag soaked in ethanol, and weigh them with an analytical balance (0.0001g) and record the weight.

[0045] The weight of sample No. 1 before torsion: 13.8174g; the weight of sample No. 2 before torsion: 141.5732g;

[0046] For No. 1 and No. 2, perform 20 / 20 forward and reverse twisting at a speed of 60r / min, and place an A4 paper underneath. After the twisting is completed, carefully remove the copper rod test to prevent the transparent glue at both ends from falling off, gently brush the sample with a soft brush, and weigh it;

[0047] The weight of sample No. 1 after twisting is: 135.8149g; the weight of sample No. 2 after twisting is: 141.5718g; the amount of powder loss is shown in Table 2.

[0048] Table 2

[0049] Sample No. Mass before twisting (g) Mass after twisting (g) Powder loss (mg) No. 1 135.8174 135.8149 2.5(D) No. 2 141.5732 141.5718 1.4(C)

[0050] The copper powder on the A4 paper of sample No. 1 and No. 2 was removed and the morphology of the copper powder was observed under a microscope. The results are as follows: Figure 1 and Figure 2 As shown. Figure 1 It can be seen that the single copper powder particles are small, the length and width uniformity is not good, and the number per unit area is relatively large (D). Figure 2 It can be seen that the single copper powder particles are relatively large, the length and width uniformity is relatively good, and the number per unit area is relatively small (C).

[0051] (3) Limit torsion measurement and fracture determination:

[0052] Install specimens No. 1 and No. 2 on the torsion testing machine. Set the parameters of the torsion testing machine to a speed of 90 r / min, 30 forward revolutions, and 40 reverse revolutions. Record the number of reverse revolutions when the copper rod breaks, and observe the fracture surface state of the copper rod.

[0053] Among them, the number of fracture circles of sample No. 1 is 26.1 (F); the fracture state: the fracture of the copper rod is flat and has no obvious burrs (H); the number of fracture circles of sample No. 2 is 24.8 (E); the fracture state: there are obvious protruding burrs and the fracture is uneven (G). The fracture of sample No. 1 is as follows Figure 3 As shown, the fracture of test No. 2 is Figure 4 shown.

[0054] (4) Metallographic analysis:

[0055] Take samples No. 1 and No. 2, both of which are 2 cm in length, for grinding and polishing;

[0056] Apply metallographic etching liquid ammonia water to the polished surface and let it stand for ten minutes. Then put it under a metallographic microscope for metallographic observation. The results of sample No. 1 are as follows Figure 5 As shown, the unit cell has a larger volume, better uniformity of unit cell distribution, and poorer density (J). The results of sample No. 2 are as follows Figure 6 As shown, the unit cell has a small volume, poor distribution uniformity and high density (I).

[0057] The test results of samples 1 and 2 are summarized in Table 3.

[0058] Table 3

[0059]

[0060] Judging from the results in Table 3, test No. 1 complies with BDFHJ and is ordinary copper, while test No. 2 complies with ACEGI and is high-speed copper.

[0061] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for distinguishing the copper grade for enameled wire, characterized in that: Including Vickers hardness test, powder loss and copper powder particle shape determination, limit torsion measurement and fracture determination and metallographic spectrum analysis; The method specifically comprises the following steps: (1) Vickers hardness test: The Vickers hardness of the enameled wire to be distinguished is measured with copper. The Vickers hardness test value is divided into two intervals, A and B, where A = 95-105 HV, B < 95 HV or > 105 HV; (2) Determination of the amount of powder loss and the morphology of copper powder particles: The enameled wire to be distinguished is twisted forward and backward for many times, and the copper powder is collected below. The morphology of the copper powder is observed under a microscope. The mass of the copper powder is divided into two intervals, C and D. Among them, C≤2.2mg, the single copper powder particle is large, the length and width uniformity is relatively good, and the number per unit area is relatively small. D>2.2mg, the single copper powder particle is small, the length and width uniformity is poor, and the number per unit area is relatively large; (3) Limit torsion measurement and fracture determination: The enameled copper wire to be distinguished is subjected to multiple forward and reverse torsion, and the number of reverse rotations when the copper breaks is recorded and the state of the copper fracture surface is observed. The number of reverse rotations is divided into two intervals, E and F, where E = 23-25 ​​rotations and F = 26-30 rotations. The fracture surface state is divided into G and H. G means that there are obvious protruding burrs and the fracture surface is uneven, and H means that the fracture surface is even after the copper rod breaks, without obvious burrs. (4) Metallographic analysis: The copper enameled wire to be distinguished is subjected to metallographic observation under a metallographic microscope. The lattice distribution is divided into I and J. Among them, I means that the single unit cell volume is small, the unit cell distribution uniformity is poor, and the density is high. J means that the single unit cell volume is large, the unit cell distribution uniformity is good, and the density is poor. (5) Determine the copper grade based on the results of steps (1)-(4); When the copper detection performance of the enameled wire to be distinguished is at ACEGI, it is high-speed copper, and when it is at BDFHJ, it is ordinary copper.

2. A method for distinguishing copper grades for enameled wire according to claim 1, characterized in that: When measuring Vickers hardness, the experimental force value is 0.3kgf, the holding time is 10s, the length of the copper used for the enameled wire to be distinguished is 2cm, the compression test is performed three times, and the average value is taken.

3. A method for distinguishing copper grades for enameled wire according to claim 1, characterized in that: When judging the amount of powder falling and the shape of copper powder particles, the forward and reverse twisting is 20 turns at a speed of 60r / min.

4. A method for distinguishing copper grades for enameled wire according to claim 3, characterized in that: Wipe the surface of the enameled wire to be distinguished clean with ethanol before weighing it with copper.

5. A method for distinguishing copper grades for enameled wire according to claim 3, characterized in that: When judging the amount of powder loss and the shape of copper powder particles, the length of the copper used to distinguish the enameled wire is 31cm.

6. A method for distinguishing copper grades for enameled wire according to claim 1, characterized in that: When measuring the limit torsion and judging the fracture, the forward rotation is 30 revolutions, the reverse rotation is 40 revolutions, and the speed is 90r / min.

7. A method for distinguishing copper grades for enameled wire according to claim 1, characterized in that: The length of the copper used to distinguish the enameled wire during metallographic analysis is 2 cm.

8. A method for distinguishing copper grades for enameled wire according to claim 1, characterized in that: During metallographic analysis, the enameled wire to be distinguished is polished with copper, and ammonia is applied to the polished surface.

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