Copper tape for transformer winding and manufacturing method thereof, and transformer winding

Abstract

The application discloses a copper strip for a transformer winding and a manufacturing method thereof and a transformer winding, and belongs to the technical field of transformer windings. The copper strip for the transformer winding comprises a large-size crystal domain copper layer and an annealed electroplated copper layer which are arranged in a stack, and the annealed electroplated copper layer is arranged on at least one side of the large-size crystal domain copper layer, and the copper grain boundary of the large-size crystal domain copper layer is less than 4 / cm 2 The transformer winding is formed by the copper strip for the transformer winding. The hardness of the copper strip for the transformer winding is in a moderate range, and the copper strip has good electrical conductivity.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of transformer winding, in particular to a copper strip for transformer winding and a manufacturing method thereof, and a transformer winding. BACKGROUND

[0002] The current transformer is generally of a metal strip winding structure, and the red copper strip winding structure can make the electric field of the transformer uniform and strong in short-circuit resistance, and is helpful to improve the stability of the electric conduction and heat conduction of the transformer and the space utilization, and thus is widely applied in the current power industry.

[0003] The hardness of the red copper strip has an important influence on the winding and performance of the transformer winding. The position with excessively high hardness can cause large product rebound force and tight winding. The position with excessively low hardness can cause longitudinal stretching, excessive size deformation and surface scratch of the winding, and finally affect the electric conductivity of the copper strip. How to improve the electric conductivity of the transformer copper strip on the basis of hardness control is a problem to be solved for further development of the transformer copper strip technology. SUMMARY

[0004] The present application provides a copper strip for transformer winding and a manufacturing method thereof, and a transformer winding, which can control the hardness of the copper strip for transformer winding in a moderate range and improve the electric conductivity of the copper strip.

[0005] The embodiments of the present application are implemented as follows:

[0006] In a first aspect, the embodiments of the present application provide a copper strip for transformer winding, which comprises: a large-size crystal domain copper layer and an annealed electroplated copper layer arranged in layers, the annealed electroplated copper layer is arranged on at least one side of the large-size crystal domain copper layer, and the copper grain boundary of the large-size crystal domain copper layer is <4 / cm 2 .

[0007] In a second aspect, the embodiments of the present application provide a manufacturing method of the copper strip for transformer winding of the first aspect, which comprises:

[0008] The electroplated copper layer is formed on the surface of the large-size crystal domain copper layer by electroplating, and then annealing is performed to obtain the copper strip.

[0009] In a third aspect, the embodiments of the present application provide a transformer winding, which is wound by the copper strip for transformer winding of the first aspect.

[0010] The copper strip for transformer winding and the manufacturing method thereof, and the transformer winding of the embodiments of the present application have the following beneficial effects:

[0011] The copper strip comprises a large-size crystal domain copper layer and an annealed electroplated copper layer, and the copper grain boundary of the large-size crystal domain copper layer is <4 / cm 2The copper band for the transformer winding has less grain boundary, and the conductive performance of the copper band for the transformer winding is better. The annealed electroplated copper layer is obtained by annealing the electroplated copper layer. The annealing treatment makes the grain of the electroplated copper layer larger and the copper grain boundary less, and can also improve the conductive performance of the copper band. In addition, the grain boundary of the large-size grain domain copper layer is less, and the copper grain boundary of the electroplated copper layer is less after the annealing treatment, so that the resistance of the large-size grain domain copper layer and the annealed electroplated copper layer to deformation is smaller, and the hardness is smaller in macroscopically, so that the upper limit of the hardness of the copper band for the transformer winding can be controlled at a lower level, and the hardness of the copper band is moderate. According to the test, the hardness of the copper band for the transformer winding in different positions of the embodiment of the present application fluctuates in the range of 44-52HV. BRIEF DESCRIPTION OF DRAWINGS

[0012] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0013] Figure 1 A structural schematic diagram of the copper band for the transformer winding according to the embodiment of the present application;

[0014] Figure 2 Another structural schematic diagram of the copper band for the transformer winding according to the embodiment of the present application;

[0015] Figure 3 A structural schematic diagram of the preparation device of the copper band for the transformer winding according to the embodiment of the present application;

[0016] Figure 4 The XRD test diagram of the copper band of Example 1 of the present application;

[0017] Figure 5 The photo of the surface of the copper band of Example 1 of the present application.

[0018] Figure legend: 10-copper band; 11-large-size grain domain copper layer; 12-annealed electroplated copper layer; 21-unwinding mechanism; 22-winding mechanism; 23-electroplating equipment; 231-cathode conductive roller; 24-first annealing mechanism; 25-second annealing mechanism. DETAILED DESCRIPTION

[0019] The embodiments of the present application will be described in detail below with examples, but those skilled in the art will understand that the following examples are only for illustration of the present application and should not be regarded as limiting the scope of the present application. The specific conditions not noted in the examples are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not noted by the manufacturer, which are all conventional products that can be obtained by market purchase.

[0020] At present, the control range of hardness of red copper strip for transformer metal winding is large, and the hardness at different positions is in the range of 45-65 HV. The hardness that is too large or too small will affect the performance of the product. The applicant found that the operation and quality control effect of the transformer copper strip winding is better when the hardness of the red copper strip is controlled in a smaller range of 45-52 HV.

[0021] In order to obtain red copper strip with moderate hardness and small hardness range, the applicant tried to reduce the upper limit of hardness by rolling and multiple low-temperature annealing (200-550℃) process of the red copper strip; on the other hand, by controlling the composition of the copper, such as adding impurity elements Fe and B, the recrystallization process hinders the grain growth, so that fine and uniform copper grains are obtained, thereby ensuring that the hardness of the copper strip is controlled in a smaller range. However, there is a disadvantage in the copper strip treated by the two methods, that is, there are still many grain boundaries in the copper strip, which will affect the electrical conductivity of the copper strip.

[0022] Based on this, the embodiments of the present application provide a copper strip 10 for transformer winding and a manufacturing method thereof and a transformer winding, which can control the hardness of the copper strip 10 for transformer winding in a moderate range and improve the electrical conductivity of the copper strip.

[0023] The copper strip 10 for transformer winding and the manufacturing method thereof and the transformer winding of the embodiments of the present application will be described in detail as follows:

[0024] In a first aspect, the embodiments of the present application provide a copper strip 10 for transformer winding, which comprises: a large-size grain domain copper layer 11 and an annealed electroplated copper layer 12 arranged in layers, and the annealed electroplated copper layer 12 is arranged on at least one side of the large-size grain domain copper layer 11 (see Figure 1 and Figure 2 The copper grain boundary of the large-size grain domain copper layer 11 is <4 / cm 2 .

[0025] It can be understood that the annealed electroplated copper layer 12 can be arranged on one side of the large-size grain domain copper layer 11, or can be arranged on opposite sides of the large-size grain domain copper layer 11.

[0026] The copper strip 10 comprises the large-size grain domain copper layer 11 and the annealed electroplated copper layer 12. Since the copper grain boundary of the large-size grain domain copper layer 11 is <4 / cm 2, the existing grain boundary is less, so that the copper strip 10 for the transformer winding has better electrical conductivity; compared with polycrystalline copper, the grain boundary of the large-size grain domain copper layer 11 is less, so that the resistance of the material deformation is smaller, and the hardness is smaller in macroscopic. Optionally, the copper grain boundary of the large-size grain domain copper layer 11 is 1 / cm 2 , 2 / cm 2 , 3 / cm 2 or 4 / cm 2 .

[0027] In addition, the annealed electroplated copper layer 12 is obtained by annealing the electroplated copper layer, and the annealing treatment makes the grain of the electroplated copper layer larger and the copper grain boundary less, which can also improve the electrical conductivity of the copper strip. At the same time, the less copper grain boundary of the electroplated copper layer makes the resistance of its deformation smaller, and the hardness is also reduced. Since the grain boundaries of the large-size grain domain copper layer 11 and the annealed electroplated copper layer 12 are both less, the upper limit of the hardness of the copper strip 10 for the transformer winding can be controlled at a lower level, and the hardness of the copper strip 10 is moderate. It has been tested that the hardness of the copper strip 10 for the transformer winding of the embodiment of the present application fluctuates in the range of 44-48.5HV at different positions.

[0028] In a possible embodiment, the thickness of the large-size grain domain copper layer 11 is 25-50um. Since the copper grain boundary of the large-size grain domain copper layer 11 of the embodiment of the present application is <4 / cm 2 , the copper grain boundary per unit area is less, and it is difficult to obtain a large-size grain domain copper layer 11 with a relatively thick thickness by the preparation process. The large-size grain domain copper layer 11 with a thickness of 25-50um is relatively easy to obtain. Optionally, the thickness of the large-size grain domain copper layer 11 is any one of 25um, 30um, 35um, 40um, 45um and 50um or a range between any two of them.

[0029] Further, in a possible embodiment, the thickness of the copper strip 10 is 0.1-2.5mm.

[0030] The copper strip 10 with a thickness of 0.1-2.5mm is relatively thick, and when applied to the transformer winding, it can improve the service life and reliability of the transformer. If the copper strip 10 with this thickness only contains the large-size grain domain copper layer 11, it is very difficult to obtain the large-size grain domain copper layer 11 with this thickness due to the extremely great difficulty of the preparation process. The copper strip 10 with a thickness of 0.1-2.5mm includes the large-size grain domain copper layer 11 with a thickness of 25-50um and the annealed electroplated copper layer 12, which not only reduces the preparation difficulty, but also can improve the service life and reliability of the transformer.

[0031] Exemplarily, the copper lattice orientation of the large-size crystal domain copper layer 11 and the annealed electroplated copper layer 12 is selected from any one of Cu(111), Cu(110), Cu(211) and Cu(100). Optionally, the copper lattice in the large-size crystal domain copper layer 11 and the annealed electroplated copper layer 12 is of the same orientation.

[0032] It is found by the applicant that the copper lattice orientations of Cu(111), Cu(110), Cu(211) and Cu(100) can make the copper strip 10 have better electrical conductivity.

[0033] Exemplarily, the peak intensity of the copper lattice of the large-size crystal domain copper layer 11 is greater than 3×10 3 The stronger the peak intensity of the copper lattice orientations of Cu(111), Cu(110), Cu(211) and Cu(100) is, the better the electrical conductivity of the copper strip 10 is. The peak intensity of the copper lattice of the large-size crystal domain copper layer 11 in the embodiment of the present application is greater than 3×10 3 which can ensure the copper strip to have better electrical conductivity.

[0034] In a second aspect, the embodiment of the present application provides a manufacturing method of the copper strip 10 for the transformer winding of the first aspect, which comprises: thickening the surface of the large-size crystal domain copper layer 11 to form an electroplated copper layer by electroplating, and then annealing to obtain the copper strip 10.

[0035] The surface of the large-size crystal domain copper layer 11 is thickened to form an electroplated copper layer by electroplating, the thickness of the copper strip 10 is thickened, the electroplating thickening mode makes the large-size crystal domain copper layer 11 and the electroplated copper layer tightly combined together, and the use reliability of the copper strip 10 is improved. In addition, the electroplated copper layer is annealed to make the grain of the electroplated copper layer larger and the copper grain boundary less, which can also improve the electrical conductivity of the copper strip 10. Meanwhile, the less copper grain boundary of the electroplated copper layer makes the resistance of the deformation smaller, and the hardness is also reduced.

[0036] Exemplarily, the current density of the electroplating is 0.3-4 ASD. If the current density is too large, it is easy to cause uneven thickening in the process of electroplating thickening. If the current density is too small, it is not easy to successfully plate copper on the surface of the large-size crystal domain copper layer 11. The current density is selected to be 0.3-4 ASD, which can make the electroplated copper layer formed on the surface of the large-size crystal domain copper layer 11 more uniformly.

[0037] Optionally, the temperature for annealing after the surface of the large-size crystal domain copper layer 11 is thickened to form the electroplated copper layer is 500-1075℃, for example, any one of 500℃, 600℃, 700℃, 800℃, 900℃, 1000℃ and 1075℃ or a range between any two of them. Optionally, the annealing time is 1-2h.

[0038] Since the grain boundaries of the large-size crystal copper layer 11 and the annealed electroplated copper layer 12 are less, the upper limit of the hardness of the copper strip 10 of the transformer winding can be controlled at a lower level, and the hardness of the copper strip 10 is moderate, and the copper strip 10 also has good electrical conductivity.

[0039] Exemplarily, the large-size crystal copper layer 11 is obtained by annealing a polycrystalline copper plate with a copper grain boundary greater than 10000 / cm 2 .

[0040] The copper grain boundary of the polycrystalline copper plate is greater than 10000 / cm 2 . After annealing, the copper grain size is increased, and the grain boundary is reduced, which can improve the electrical conductivity of the copper strip 10 and reduce the hardness. Optionally, the annealing temperature of the polycrystalline copper plate is 800-1075°C, and under this temperature condition, the copper grain size of the polycrystalline copper plate can be greatly increased, and the grain boundary can be reduced as much as possible. Exemplarily, the annealing temperature of the polycrystalline copper plate is any one of 800°C, 900°C, 1000°C and 1075°C, or a range between any two of them. In addition, the annealing time of the polycrystalline copper plate is 1-4h, for example, 1h, 2h, 3h or 4h.

[0041] In one possible embodiment, the copper strip 10 for the transformer winding is prepared in a "low tension + roll-to-roll high-temperature annealing + roll-to-roll electroplating" device, wherein the "low tension + roll-to-roll high-temperature annealing + roll-to-roll electroplating" device comprises an unwinding mechanism 21, a winding mechanism 22, an annealing device and an electroplating device 23 (see Figure 3 ).

[0042] The annealing device comprises a first annealing mechanism 24 and a second annealing mechanism 25. The unwinding mechanism 21, the first annealing mechanism 24, the electroplating device 23, the second annealing mechanism 25 and the winding mechanism 22 are sequentially arranged, and the first annealing mechanism 24 and the second annealing mechanism 25 each have a heating section and a cooling section. The two ends of the polycrystalline copper plate are respectively wound on the unwinding mechanism 21 and the winding mechanism 22, and the polycrystalline copper plate bears a tension of 30-100N per meter of width, and the polycrystalline copper plate is sequentially treated by the first annealing mechanism 24, the electroplating device 23 and the second annealing mechanism 25. Since the polycrystalline copper plate is soft, when the winding mechanism 22 and the unwinding mechanism 21 apply tension to the polycrystalline copper plate, the polycrystalline copper plate bears a low tension of 30-100N, which can avoid breaking or stretching of the polycrystalline copper plate.

[0043] The polycrystalline copper plate sequentially passes through a heating section, a high-temperature annealing section and a cooling section in the first annealing mechanism 24. In the heating section, an inert gas such as N2, Ar or He is introduced and heated. When the polycrystalline copper plate enters the high-temperature annealing section of the first annealing mechanism 24, a reducing gas such as H2 or CO is introduced to start annealing. After annealing, the polycrystalline copper plate enters the cooling section, the temperature is reduced to room temperature, and a large-size crystal copper layer 11 is obtained.

[0044] The large-size grain copper layer 11 is thickened by electroplating in the electroplating device 23, the electroplating device 23 is provided with a plurality of groups of cathode conductive rollers 231, each group of cathode conductive rollers 231 includes one cathode conductive roller 231 or two cathode conductive rollers 231 rotating in opposite directions, wherein the cathode conductive roller 231 is used as a cathode, the electroplating device 23 is provided with an anode and an electrolyte, the large-size grain copper layer 11 is thickened by electroplating in a roll-to-roll electroplating manner, a copper layer is formed on the surface of the large-size grain copper layer 11, and then water washing and drying are performed, and then the copper layer is annealed in the second annealing mechanism 25 to obtain the copper tape 10 for the transformer winding, and subsequent slitting and cutting can be performed.

[0045] In a third aspect, the embodiments of the present application provide a transformer winding, which is wound by the copper tape 10 for the transformer winding of the first aspect.

[0046] Since the copper tape 10 has moderate hardness and good electrical conductivity, the transformer winding wound by the copper tape 10 has good electrical conductivity, compact winding, and good quality.

[0047] The copper tape for the transformer winding and the manufacturing method thereof, and the transformer winding are further described in detail below in combination with embodiments.

[0048] Embodiment 1

[0049] The embodiment provides a copper tape for a transformer winding, which includes a large-size grain copper layer and an annealed electroplated copper layer arranged in layers, and the large-size grain copper layer is provided with the annealed electroplated copper layer on one side, and the manufacturing method thereof includes:

[0050] A polycrystalline copper plate with a thickness of 40 um (the number of grain boundaries is 8100 / cm 2 ) is annealed at 1000℃ to obtain a large-size grain copper layer, the large-size grain copper layer is thickened by electroplating to form an electroplated copper layer with a thickness of 400 um on the surface of the large-size grain copper layer, and then the copper tape with the large-size grain copper layer and the annealed electroplated copper layer is obtained by annealing at 800℃.

[0051] Embodiment 2

[0052] The embodiment provides a copper tape for a transformer winding, which includes a large-size grain copper layer and an annealed electroplated copper layer arranged in layers, and the large-size grain copper layer is provided with the annealed electroplated copper layer on one side, and the manufacturing method thereof includes:

[0053] A polycrystalline copper plate with a thickness of 25 um (the number of grain boundaries is 9000 / cm 2) performing first annealing at 900℃ to obtain a large-grain copper layer, performing electroplating thickening on the large-grain copper layer to form an electroplated copper layer with a thickness of 800um on the surface of the large-grain copper layer, and then performing second annealing at 600℃ to obtain a copper tape with the large-grain copper layer and the annealed electroplated copper layer.

[0054] Example 3

[0055] The embodiment provides a copper tape for a transformer winding, which comprises a large-grain copper layer and an annealed electroplated copper layer arranged in a stack, and the large-grain copper layer is provided with the annealed electroplated copper layer on both sides, and a preparation method thereof comprises the following steps of:

[0056] polycrystalline copper plates with a thickness of 75um (the number of grain boundaries is 8100 / cm 2 ) performing first annealing at 950℃ to obtain a large-grain copper layer, performing electroplating thickening on the large-grain copper layer to form an electroplated copper layer with a thickness of 100um on the surface of the large-grain copper layer, and then performing second annealing at 700℃ to obtain a copper tape with the large-grain copper layer and the annealed electroplated copper layer.

[0057] Example 4

[0058] The embodiment provides a copper tape for a transformer winding, which comprises a large-grain copper layer and an annealed electroplated copper layer arranged in a stack, and the large-grain copper layer is provided with the annealed electroplated copper layer on both sides, and a preparation method thereof comprises the following steps of:

[0059] polycrystalline copper plates with a thickness of 15um (the number of grain boundaries is 9000 / cm 2 ) performing first annealing at 900℃ to obtain a large-grain copper layer, performing electroplating thickening on the large-grain copper layer to form an electroplated copper layer with a thickness of 800um on the surface of the large-grain copper layer, and then performing second annealing at 600℃ to obtain a copper tape with the large-grain copper layer and the annealed electroplated copper layer.

[0060] Comparative Example 1

[0061] The comparative example provides a copper tape for a transformer winding, which comprises a large-grain copper layer and an electroplated copper layer arranged in a stack, and the large-grain copper layer is provided with the electroplated copper layer on one side, and a preparation method thereof comprises the following steps of:

[0062] polycrystalline copper plates with a thickness of 40um (the number of grain boundaries is 8100 / cm 2 ) performing first annealing at 1000℃ to obtain a large-grain copper layer, performing electroplating thickening on the large-grain copper layer to form an electroplated copper layer with a thickness of 400um on the surface of the large-grain copper layer, and thus obtaining a copper tape.

[0063] Comparative Example 2

[0064] The present comparative example provides a copper strip for transformer winding, which comprises a polycrystalline copper plate and an electroplated copper layer arranged in a stack, the electroplated copper layer is arranged on one side of the polycrystalline copper plate, and the preparation method comprises the following steps:

[0065] A polycrystalline copper plate with a thickness of 40 um is electroplated to thicken the surface of the polycrystalline copper plate to form an electroplated copper layer with a thickness of 400 um, thereby obtaining a copper strip.

[0066] Test Example 1

[0067] The large-size grain domain copper layer prepared in Example 1 and Example 2 and the polycrystalline copper plate of Example 1 and Example 2 are detected for performance, and the results are recorded in Table 1, and the detection method is as follows:

[0068] (1) Grain boundary number detection: metallographic microscope observation, randomly take the grain boundary number in the range of 250*400 mm.

[0069] (2) Hardness: GB-T4340.1-2009.

[0070] (3) Electrical conductivity: GB-T351-2009.

[0071] (4) Copper purity and oxygen content detection: GB / T 5121.1-2008.

[0072] Table 1. Performance test results of large-size grain domain copper layer and polycrystalline copper plate

[0073]

[0074]

[0075] As can be seen from the results in Table 1, compared with the polycrystalline copper plate, the large-size grain domain copper layer of the present application has higher electrical conductivity and smaller hardness.

[0076] Test Example 2

[0077] The copper strip prepared in Example 1 is subjected to XRD test, and the results are shown in Figure 4 As can be seen from the results in Figure 4 , the copper strip of Example 1 of the present application has obvious Cu(111) single crystal copper lattice orientation.

[0078] Test Example 3

[0079] The surface of the copper strip prepared in Example 1 is observed (as shown in Figure 5 ), and the surface of the copper strip has grain boundaries of large-size grain domains.

[0080] Test Example 4

[0081] The hardness of the copper strips prepared in Example 1-4 and Comparative Example 1-2 was detected according to GB-T 4340.1-2009, and the results are recorded in Table 2.

[0082] Table 2. Hardness of the copper strips of Example 1-4 and Comparative Example 1-2

[0083]

[0084] From the results in Table 2, it can be seen that the hardness of the copper strips of Example 1-4 is less than that of Comparative Example 1 and Comparative Example 2, and the hardness of Example 1-4 is in the range of 44-51 HV, which is appropriate. By comparing Example 1 with Comparative Example 1, the electroplated copper layer of Comparative Example 1 is not annealed, which results in the hardness of Comparative Example 1 being significantly greater than that of Example 1. By comparing Example 1 with Comparative Example 2, the polycrystalline copper plate in Comparative Example 2 is directly electroplated to thicken, and neither the polycrystalline copper plate nor the electroplated copper layer is annealed, which results in the hardness of Comparative Example 2 being significantly greater than that of Example 1.

[0085] The above only describes specific embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A copper tape for use in a transformer winding, characterized in that, It comprises: A large-size crystal domain copper layer and an annealed electroplated copper layer are arranged in layers, at least one side of the large-size crystal domain copper layer is provided with the annealed electroplated copper layer, and the copper grain boundary of the large-size crystal domain copper layer is < 4 / cm 2 The thickness of the copper strip is 0.44-2.5 mm, and the hardness is 44-52 HV.

2. The copper tape for transformer windings according to claim 1, characterized in that, The thickness of the large-size crystal domain copper layer is 25-50 μm.

3. The copper strip for transformer windings according to claim 1 or 2, characterized in that, The copper crystal lattice orientation of the large-size crystal domain copper layer and the annealed electroplated copper layer is selected from any one of Cu (111), Cu (110), Cu (211) and Cu (100).

4. The copper tape for transformer windings according to claim 3, characterized in that, The peak intensity of the copper crystal lattice of the large-size crystal domain copper layer is > 3 x 10 3 .

5. A method of manufacturing a copper strip for a transformer winding as claimed in any one of claims 1 to 4, characterised in that, It comprises: The electroplated copper layer is formed on the surface of the large-size crystal domain copper layer by electroplating, and then annealing is performed to obtain the copper tape.

6. The method of making a copper tape for a transformer winding of claim 5, wherein, The large-size crystal grain copper layer is obtained by annealing a polycrystalline copper plate with a copper grain boundary greater than 10000 / cm 2 .

7. The method of making a copper tape for a transformer winding of claim 6, wherein, The annealing temperature of the polycrystalline copper plate is 800-1075 ℃.

8. The method of making a copper tape for a transformer winding of claim 5, wherein, The annealing temperature after the electroplated copper layer is formed on the surface of the large-size crystal domain copper layer is 500-1075 ℃.

9. A transformer winding, characterized by It is made of the copper tape for transformer winding according to any one of claims 1-4.

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