Local electric heating treatment process for improving welding structure uniformity of titanium cathode roller

Abstract

The invention belongs to the technical field of titanium-based cathode rollers, and discloses a local electric heating treatment process for improving the welding structure uniformity of a titanium cathode roller, which comprises the following steps of: applying direct current to a welding seam from two sides of the welding seam after titanium material friction stir welding, controlling the direct current to be 65-70A / mm < 2 > and the electrifying time to be 3-5s, and completing local electric heating treatment; and in the direct current applying process, the welding seam is in the protective atmosphere. The welding seam is subjected to electric heating treatment by controlling the current magnitude and the current time, so that the structure at the welding seam is recrystallized, crystal grains grow and are approximately consistent with the structure of a base material, and the aim of homogenization is achieved. The method provided by the invention effectively solves the influence of the grain size difference between the cathode roller welding seam and the base material on the strength difference and the defect of the surface appearance during foil generation.

Description

Technical Field

[0001] The invention belongs to the technical field of titanium-based cathode rollers, and in particular relates to a local electric heat treatment process for improving the uniformity of the welding structure of a titanium cathode roller. Background Art

[0002] Titanium cathode roller is the core supporting equipment in the production of electrolytic copper foil. It is called the heart of electrolytic copper foil production. Its quality directly determines the grade and quality of copper foil. As one of the basic materials of the electronics industry, electrolytic copper foil is mainly used to manufacture printed circuit boards (PCBs) and lithium-ion batteries. It is widely used in communications, medical, aerospace, military, new energy and other fields, all of which belong to key areas. There are two main manufacturing processes for cathode rollers: spinning and welding. The titanium cathode roller manufactured by spinning has the advantages of uniform surface grain size, no bright bands, color difference and other defects in the copper foil produced, and easy processing. However, the titanium cylinder ring blank must go through the process steps of vacuum melting, ingot division, forging, punching, hole expansion, ring rolling, ring turning, spinning and other process steps of sponge titanium before spinning. The process is complicated and costly. The welding process is inexpensive and the preparation steps are simple. Compared with the spinning process, it can reduce the preparation cost and optimize the preparation process to a certain extent. However, there is a longitudinal weld on the surface of the welded cathode roller. If the welding and post-processing processes are not well controlled, light spots or bright bands will appear at the corresponding positions of the copper foil, which will seriously affect and restrict the high-quality and high-efficiency production of copper foil. Therefore, the development of welded cathode rollers with higher surface grain size grade, uniform microstructure and consistent grain size is a key issue.

[0003] Compared with the traditional melting welding process, the friction stir welding technology has low welding heat input, small residual stress, high welding efficiency, and is conducive to welding large-sized cathode rollers. However, due to the large difference between the weld structure and the parent material structure after welding, the cathode roller will produce color difference, bright bands and other problems in the production of electrolytic copper foil, so it is necessary to treat the weld to further improve the structure. Summary of the invention

[0004] In view of the above-mentioned deficiencies and defects of the prior art, the object of the present invention is to provide a local electrothermal treatment process for improving the uniformity of the welding structure of the titanium cathode roller, and to solve the problem of uneven grain size of the cathode roller prepared by welding.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems: A local electrothermal treatment process for improving the uniformity of titanium cathode roller welding structure includes the following processes: A direct current is applied to the weld from both sides of the weld after friction stir welding of titanium materials. The magnitude of the direct current is 65~70A / mm 2 The power-on time is 3~5s to complete the local electric heat treatment; during the application of DC current, the weld is in a protective atmosphere.

[0006] Preferably, in terms of mass percentage, the impurity element composition and content of the titanium material are as follows: Fe≤0.05%, C≤0.03%, N≤0.03%, O≤0.06%, H≤0.002%.

[0007] Preferably, when the titanium material is subjected to friction stir welding, the material of the stirring head is W-Re alloy, the rotation speed of the stirring head is 80-200 r / min, and the forward speed is 80-150 mm / min.

[0008] Preferably, when the titanium material is subjected to friction stir welding, argon gas is introduced into the weld for protection.

[0009] Preferably, when applying direct current to the weld from both sides of the weld after friction stir welding of the titanium material, electrodes are arranged on both sides of the weld on the surface of the titanium material, the electrodes are in contact with the surface of the titanium material, and then direct current is applied to the weld through the electrodes.

[0010] Preferably, the electrode is an electrode plate, and one side edge of the electrode plate is in contact with the edge of the weld.

[0011] Preferably, the electrode is an electrode column, a plurality of electrode columns are arranged at intervals along the weld, and the edge of the electrode column contacts the edge of the weld.

[0012] Preferably, the distance between the electrode columns is 5-7 cm.

[0013] The present invention also provides a titanium cathode roller, which is manufactured by a stir friction welding manufacturing process, and the weld on the cathode roller is treated by the local electrothermal treatment process for improving the uniformity of the titanium cathode roller welding structure as described above.

[0014] Preferably, the base material, heat-affected zone and stirred zone at the weld are uniform equiaxed crystals.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The local electric heat treatment process for improving the uniformity of the titanium cathode roller welding structure of the present invention is essentially to perform electric heat treatment on the weld by controlling the current size and current time through the local current heat treatment process, so that the structure at the weld undergoes recrystallization and grain growth, and then becomes close to the same as the parent material structure, thereby achieving the purpose of uniformity. The method of the present invention effectively solves the influence of the difference in grain size between the cathode roller weld and the parent material on the difference in strength when the foil is produced and the defects in the surface morphology. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG1(a) is a schematic diagram of a local electric heat treatment device used in an embodiment of the present invention; FIG1(b) is a top view of FIG1(a); and FIG1(c) is a left view of FIG1(a); FIG2 (a) is a microstructure morphology of a titanium plate base material (BM) prepared in Example 1 of the present invention; FIG2 (b) is a microstructure morphology of a heat affected zone (HAZ) of a titanium plate prepared in Example 1 of the present invention; FIG2 (c) is a microstructure morphology of a stirring zone (SZ) of a titanium plate prepared in Example 1 of the present invention; FIG3 (a) is the microstructure morphology of the titanium plate base material (BM) prepared in Comparative Example 1 of the present invention; FIG3 (b) is the microstructure morphology of the stirring zone (SZ) of the titanium plate prepared in Comparative Example 1 of the present invention.

[0017] Among them: 1-power supply, 2-digital temperature detector, 3-thermocouple, 4-industrial pure titanium TA1 plate, 5-bakelite insulator, 5-1-through hole, 6-welding seam, 7-electrode. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] The present invention proposes a local electrothermal treatment process for improving the uniformity of titanium cathode roller welding structure. Specifically, the method comprises the following steps: Step 1, performing friction stir welding on a titanium material to prepare a welded titanium material; Specifically, in terms of mass percentage, the impurity element composition and content of industrial pure titanium are Fe≤0.05%, C≤0.03%, N≤0.03%, O≤0.06%, and H≤0.002%.

[0020] Specifically, the stirring head is made of W-Re alloy, the stirring head rotation speed is 80~200r / min, and the forward speed is 80~150mm / min.

[0021] Specifically, argon protective gas is introduced during the friction stir welding process.

[0022] Step 2, inserting a thermocouple under the welding titanium material prepared in step 1; Specifically, 3 to 5 thermocouples are evenly distributed along the current direction to measure the temperature change of the plate when the power is turned on. The thermocouples in this step are only set up in the experiment to obtain the temperature change of the plate. For actual processing, there is no need to set up thermocouples.

[0023] Step 3, use the titanium material prepared in step 1 to connect the positive and negative electrodes of the power supply on both sides of the weld, as shown in Figure 1 (a) to Figure 1 (c). The present invention designs a local electric heat treatment device, which includes two bakelite insulators 5 with the same structure. The bakelite insulator 5 is horizontally opened near the top with a through hole 5-1 for setting the titanium material. The top of the bakelite insulator 5 is threadedly connected with an electrode 7, and the lower end of the electrode 7 can be inserted into the through hole 5-1 and abut against the upper surface of the industrial pure titanium TA1 plate 4; when in use, the edge of the lower end of the electrode 7 needs to abut against the edge of the weld 6 to ensure that the current is only applied to the weld; the example shown in Figure 1 (a) to Figure 1 (c) is that the electrode 7 is in the form of an electrode column. In addition, an electrode plate can also be set at the top of the inner cavity of the through hole 5-1. At this time, the electrode 7 shown in the figure can be a terminal, which is threadedly connected to the bakelite insulator 5. By rotating the terminal, the electrode plate can be close to the upper surface of the industrial pure titanium TA1 plate 4, and the edge of the electrode plate needs to abut against the edge of the weld 6 to ensure that the current is only applied to the weld; Step 4, turn on the power supply, adjust the current size and power-on time, realize current heat treatment, and obtain a titanium material with a relatively uniform structure.

[0024] In step 4, when current flows through the titanium material, Joule heat is generated. And the resistance R can be calculated as:

[0025]

[0026] Where I is the average current; is the resistor; ∆t is the duration of the current; L is the length; A is the cross-sectional area; is the resistivity.

[0027] In step 4, due to the short duration, the radiant heat emission from the titanium surface to the surrounding environment can be ignored. The change of heat generated during the current Therefore, It can be calculated as:

[0028] In the formula is the specific heat capacity; m is the mass of the substance.

[0029] In step 4, the increment of the titanium material temperature is It can be roughly estimated as:

[0030] Where V is the sample volume; q is the material density.

[0031] Through calculation and experiment, the current size is 65~70A / mm 2 , the power-on time is 3~5s.

[0032] Specifically, argon protective gas is introduced during the power-on process.

[0033] Preferably, the preparation process in step 1 is stir friction welding. The stirring head speed is 80-200 r / min, for example, 80 r / min, 100 r / min, 150 r / min and 200 r / min and any value therebetween; the forward speed is 80-150 mm / min, for example, 80 mm / min, 100 mm / min, 120 mm / min and 150 mm / min and any value therebetween.

[0034] Preferably, in step 4, the current is adjusted to 65-70A / mm 2 And the power-on time is 3~5s. For example, 65~70A / mm 2 , 3~5s and any value in between.

[0035] The following embodiments are only used to verify the feasibility of the technical solution of the present invention. In actual operation, there is no need to set a thermocouple. When setting electrodes at the same time, as long as it can ensure that a direct current is applied to the weld from both sides of the weld, other auxiliary devices (such as bakelite insulators) can be determined according to actual conditions. The local electric heat treatment device used in the embodiments of the present invention does not constitute a limitation on the technical solution of the present invention. In the following embodiments of the present invention, the electrode 7 adopts an electrode column, and the spacing between the electrode columns is 6 cm.

[0036] Example 1 This embodiment provides a local electric heat treatment process for improving the uniformity of titanium cathode roller welding structure. In this embodiment, industrial pure titanium is subjected to stir friction welding at a stirring head speed of 100 r / min and a forward speed of 80 mm / min, and then subjected to local current heat treatment to prepare a titanium material with uniform grain size between the weld and the base material. The specific steps are as follows: Step 1: Select two 200mm×70mm×3mm industrial pure titanium TA1 plates for stir friction welding. The stirring head speed is 100 r / min, the forward speed is 80mm / min, and argon protective gas is introduced during welding.

[0037] Step 2: Punch the bottom of the titanium weld after welding, pre-make three holes every 3mm along the weld and connect a thermocouple to measure the temperature.

[0038] Step 3: Connect the positive and negative electrodes of the power supply to both sides of the weld and adjust the current to 65A / mm 2 , the power-on time is 5s, and local electric heat treatment process is carried out.

[0039] The successful implementation of this embodiment prepared a welded titanium material with uniform and equiaxed grains, as shown in Figures 2(a), 2(b) and 2(c). It can be seen that the base material, heat-affected zone and stirred zone are all equiaxed grains, and the grain sizes are close. The average grain sizes of the base material, heat-affected zone and stirred zone are 38.7µm, 43.7µm and 40.4µm, respectively. It can be seen that the average grain sizes of the obtained titanium material are basically the same.

[0040] Comparative Example 1 The industrial pure titanium was subjected to friction stir welding with a stirring head speed of 100 r / min and a forward speed of 80 mm / min, and then subjected to local current heat treatment to prepare titanium material with uniform grain size between the weld and the base material. The specific steps are as follows: Step 1: Select two 200mm×70mm×3mm industrial pure titanium TA1 plates for stir friction welding. The stirring head speed is 100 r / min, the forward speed is 80mm / min, and argon protective gas is introduced during welding.

[0041] Step 2: Punch the bottom of the titanium weld after welding, pre-make three holes every 3mm along the weld and connect a thermocouple to measure the temperature.

[0042] Step 3: Connect the positive and negative electrodes of the power supply to both sides of the weld and adjust the current to 80A / mm 2 , the power-on time is 5s, and local electric heat treatment process is carried out.

[0043] As shown in Figure 3 (a) and Figure 3 (b), as the current increases, the heat generated at the weld increases. When the temperature is higher than the appropriate temperature, the grains continue to grow, and the grain size becomes larger than that of the parent material, making the grain size of the structure uneven.

[0044] Comparative Example 2 The industrial pure titanium was subjected to friction stir welding with a stirring head speed of 100 r / min and a forward speed of 80 mm / min, and then subjected to local current heat treatment to prepare titanium material with uniform grain size between the weld and the base material. The specific steps are as follows: Step 1: Select two 150mm×70mm×3mm industrial pure titanium TA1 plates for stir friction welding. The stirring head speed is 100 r / min, the forward speed is 80mm / min, and argon protective gas is introduced during welding.

[0045] Step 2: Punch the bottom of the titanium weld after welding, pre-make three holes every 3mm along the weld and connect a thermocouple to measure the temperature.

[0046] Step 3: Connect the positive and negative electrodes of the power supply to both sides of the weld and adjust the current to 65A / mm 2 , the power-on time is 10s, and local electric heat treatment process is carried out.

[0047] As the power-on time increases, heat is continuously generated at the weld, causing the grains to continue to grow after they have grown to a suitable size. The grain size becomes larger than that of the parent material, making the grain size of the organization uneven.

[0048] Example 2 This embodiment provides a local electric heat treatment process for improving the uniformity of titanium cathode roller welding structure. In this embodiment, industrial pure titanium is subjected to stir friction welding at a stirring head speed of 150r / min and a forward speed of 80mm / min, and then subjected to local current heat treatment to prepare a titanium material with uniform grain size between the weld and the parent material. The specific steps are as follows: Step 1: Select two 200mm×70mm×3mm industrial pure titanium TA1 plates for stir friction welding. The stirring head speed is 150 r / min, the forward speed is 80mm / min, and argon protective gas is introduced during welding.

[0049] Step 2: Punch the bottom of the titanium weld after welding, pre-make three holes every 3mm along the weld and connect a thermocouple to measure the temperature.

[0050] Step 3: Connect the positive and negative electrodes of the power supply to both sides of the weld and adjust the current to 68A / mm 2 , the power-on time is 4s, and local electric heat treatment process is carried out.

[0051] The successful implementation of this embodiment produces a welded titanium material with equiaxed and uniformly distributed grains, and the average grain size is 35.4 μm.

[0052] Example 3 This embodiment provides a local electric heat treatment process for improving the uniformity of titanium cathode roller welding structure. In this embodiment, industrial pure titanium is subjected to stir friction welding at a stirring head speed of 200r / min and a forward speed of 80mm / min, and then subjected to local current heat treatment to prepare a titanium material with uniform grain size between the weld and the base material. The specific steps are as follows: Step 1: Select two 150mm×70mm×3mm industrial pure titanium TA1 plates for stir friction welding. The stirring head speed is 200 r / min, the forward speed is 50mm / min, and argon protective gas is introduced during welding.

[0053] Step 2: After welding, the bottom of the titanium weld is punched, three holes are pre-made every 3 mm along the weld and thermocouples are connected to measure the temperature.

[0054] Step 3: Connect the positive and negative electrodes of the power supply to both sides of the weld and adjust the current to 70A / mm 2 , the power-on time is 3s, and local electric heat treatment process is carried out.

[0055] The successful implementation of this embodiment produces a welded titanium material with equiaxed and uniformly distributed grains, and the average grain size is 37.6 μm.

[0056] The method of the present invention uses a stir friction welding process to produce a welded joint with excellent mechanical properties. The joint strength usually exceeds that of a conventional fusion welded joint, and the deformation is small, which helps to maintain the precise size and shape of the cathode roller titanium cylinder and reduces the need for subsequent processing and correction. The welding has high thermal efficiency, which helps to reduce energy consumption and reduce the impact on the environment, improves the efficiency and accuracy of cathode roller titanium cylinder processing and forming, and is conducive to welding large-sized cathode rollers.

[0057] The above descriptions are only embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the specification of the present invention, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A local electrothermal treatment process for improving the uniformity of titanium cathode roller welding structure, characterized in that: The process includes the following: A direct current is applied to the weld (6) from both sides of the weld (6) after the titanium material is stir-friction welded, and the magnitude of the direct current is 65-70 A / mm 2 The power-on time is 3 to 5 seconds to complete the local electric heat treatment; during the application of direct current, the weld (6) is in a protective atmosphere.

2. A local electrothermal treatment process for improving the uniformity of titanium cathode roller welding structure according to claim 1, characterized in that: In terms of mass percentage, the impurity element composition and content of the titanium material are as follows: Fe≤0.05%, C≤0.03%, N≤0.03%, O≤0.06%, H≤0.002%.

3. The local electrothermal treatment process for improving the uniformity of titanium cathode roller welding structure according to claim 1, characterized in that: When friction stir welding of titanium materials is performed, the stirring head material is W-Re alloy, the stirring head speed is 80~200r / min, and the forward speed is 80~150mm / min.

4. A local electrothermal treatment process for improving the uniformity of titanium cathode roller welding structure according to claim 3, characterized in that: When friction stir welding of titanium materials is performed, argon gas is introduced into the weld for protection.

5. The local electrothermal treatment process for improving the uniformity of titanium cathode roller welding structure according to claim 1, characterized in that: When applying direct current to the weld (6) from both sides of the weld (6) after friction stir welding of the titanium material, electrodes are arranged on both sides of the weld (6) on the surface of the titanium material, the electrodes are in contact with the surface of the titanium material, and then direct current is applied to the weld (6) through the electrodes.

6. A local electrothermal treatment process for improving the uniformity of titanium cathode roller welding structure according to claim 5, characterized in that: The electrode is an electrode plate, and one side edge of the electrode plate is in contact with the edge of the weld (6).

7. A local electrothermal treatment process for improving the uniformity of titanium cathode roller welding structure according to claim 5, characterized in that: The electrode adopts an electrode column, and a plurality of electrode columns are arranged at intervals along the weld (6), and the edge of the electrode column contacts the edge of the weld (6).

8. A local electrothermal treatment process for improving the uniformity of titanium cathode roller welding structure according to claim 7, characterized in that: The distance between the electrode columns is 5~7cm.

9. A titanium cathode roller, characterized in that: The cathode roller is manufactured by a stir friction welding manufacturing process, and the weld on the cathode roller is treated by a local electrothermal treatment process for improving the uniformity of the titanium cathode roller welding structure as described in any one of claims 1 to 8.

10. A titanium cathode roller according to claim 9, characterized in that: The base material, heat affected zone and stirred zone at the weld are uniform equiaxed grains.

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